context.
This is essentially an abstract superclass, and the behavior is
-determined by the "methods" pointer is its virtual function table
-(struct MemoryContextMethods). Specific memory context types will use
-derived structs having these fields as their first fields. All the
+determined by the "methods" pointer which references which set of
+MemoryContextMethods are to be used. Specific memory context types will
+use derived structs having these fields as their first fields. All the
contexts of a specific type will have methods pointers that point to
-the same static table of function pointers.
+the corresponding element in the mcxt_methods[] array as defined in mcxt.c.
While operations like allocating from and resetting a context take the
relevant MemoryContext as a parameter, operations like free and
realloc are trickier. To make those work, we require all memory
context types to produce allocated chunks that are immediately,
-without any padding, preceded by a pointer to the corresponding
-MemoryContext.
+without any padding, preceded by a uint64 value of which the least
+significant 3 bits are set to the owning context's MemoryContextMethodID.
+This allows the code to determine the correct MemoryContextMethods to
+use by looking up the mcxt_methods[] array using the 3 bits as an index
+into that array.
If a type of allocator needs additional information about its chunks,
like e.g. the size of the allocation, that information can in turn
-precede the MemoryContext. This means the only overhead implied by
-the memory context mechanism is a pointer to its context, so we're not
-constraining context-type designers very much.
-
-Given this, routines like pfree determine their corresponding context
-with an operation like (although that is usually encapsulated in
-GetMemoryChunkContext())
-
- MemoryContext context = *(MemoryContext*) (((char *) pointer) - sizeof(void *));
-
-and then invoke the corresponding method for the context
-
- context->methods->free_p(pointer);
-
+either be encoded into the remaining 61 bits of the preceding uint64 value
+or if more space is required, additional values may be stored directly prior
+to the uint64 value. It is up to the context implementation to manage this.
+
+Given this, routines like pfree can determine which set of
+MemoryContextMethods to call the free_p function for by calling
+GetMemoryChunkMethodID() and finding the corresponding MemoryContextMethods
+in the mcxt_methods[] array. For convenience, the MCXT_METHOD() macro is
+provided, making the code as simple as:
+
+void
+pfree(void *pointer)
+{
+ MCXT_METHOD(pointer, free_p)(pointer);
+}
+
+All of the current memory contexts make use of the MemoryChunk header type
+which is defined in memutils_memorychunk.h. This suits all of the existing
+context types well as it makes use of the remaining 61-bits of the uint64
+header to efficiently encode the size of the chunk of memory (or freelist
+index, in the case of aset.c) and the number of bytes which must be subtracted
+from the chunk in order to obtain a reference to the block that the chunk
+belongs to. 30 bits are used for each of these. If more than 30 bits are
+required then the memory context must manage that itself. This can be done by
+calling the MemoryChunkSetHdrMaskExternal() function on the given chunk.
+Currently, each memory context type stores large allocations on dedicated
+blocks (which always contain only a single chunk). For these, finding the
+block is simple as we know that the chunk must be the first on the given
+block, so the block is always at a fixed offset to the chunk. For these,
+finding the size of the chunk is also simple as the block always stores an
+endptr which we can use to calculate the size of the chunk.
More Control Over aset.c Behavior
---------------------------------
#include "port/pg_bitutils.h"
#include "utils/memdebug.h"
#include "utils/memutils.h"
+#include "utils/memutils_memorychunk.h"
+#include "utils/memutils_internal.h"
/*--------------------
* Chunk freelist k holds chunks of size 1 << (k + ALLOC_MINBITS),
* CAUTION: ALLOC_MINBITS must be large enough so that
* 1<<ALLOC_MINBITS is at least MAXALIGN,
* or we may fail to align the smallest chunks adequately.
- * 8-byte alignment is enough on all currently known machines.
+ * 8-byte alignment is enough on all currently known machines. This 8-byte
+ * minimum also allows us to store a pointer to the next freelist item within
+ * the chunk of memory itself.
*
* With the current parameters, request sizes up to 8K are treated as chunks,
* larger requests go into dedicated blocks. Change ALLOCSET_NUM_FREELISTS
*/
#define ALLOC_BLOCKHDRSZ MAXALIGN(sizeof(AllocBlockData))
-#define ALLOC_CHUNKHDRSZ sizeof(struct AllocChunkData)
+#define ALLOC_CHUNKHDRSZ sizeof(MemoryChunk)
typedef struct AllocBlockData *AllocBlock; /* forward reference */
-typedef struct AllocChunkData *AllocChunk;
/*
* AllocPointer
*/
typedef void *AllocPointer;
+/*
+ * AllocFreeListLink
+ * When pfreeing memory, if we maintain a freelist for the given chunk's
+ * size then we use a AllocFreeListLink to point to the current item in
+ * the AllocSetContext's freelist and then set the given freelist element
+ * to point to the chunk being freed.
+ */
+typedef struct AllocFreeListLink
+{
+ MemoryChunk *next;
+} AllocFreeListLink;
+
+/*
+ * Obtain a AllocFreeListLink for the given chunk. Allocation sizes are
+ * always at least sizeof(AllocFreeListLink), so we reuse the pointer's memory
+ * itself to store the freelist link.
+ */
+#define GetFreeListLink(chkptr) \
+ (AllocFreeListLink *) ((char *) (chkptr) + ALLOC_CHUNKHDRSZ)
+
+/* Determine the size of the chunk based on the freelist index */
+#define GetChunkSizeFromFreeListIdx(fidx) \
+ ((((Size) 1) << ALLOC_MINBITS) << (fidx))
+
/*
* AllocSetContext is our standard implementation of MemoryContext.
*
MemoryContextData header; /* Standard memory-context fields */
/* Info about storage allocated in this context: */
AllocBlock blocks; /* head of list of blocks in this set */
- AllocChunk freelist[ALLOCSET_NUM_FREELISTS]; /* free chunk lists */
+ MemoryChunk *freelist[ALLOCSET_NUM_FREELISTS]; /* free chunk lists */
/* Allocation parameters for this context: */
Size initBlockSize; /* initial block size */
Size maxBlockSize; /* maximum block size */
/*
* AllocBlock
* An AllocBlock is the unit of memory that is obtained by aset.c
- * from malloc(). It contains one or more AllocChunks, which are
- * the units requested by palloc() and freed by pfree(). AllocChunks
+ * from malloc(). It contains one or more MemoryChunks, which are
+ * the units requested by palloc() and freed by pfree(). MemoryChunks
* cannot be returned to malloc() individually, instead they are put
* on freelists by pfree() and re-used by the next palloc() that has
* a matching request size.
} AllocBlockData;
/*
- * AllocChunk
- * The prefix of each piece of memory in an AllocBlock
- *
- * Note: to meet the memory context APIs, the payload area of the chunk must
- * be maxaligned, and the "aset" link must be immediately adjacent to the
- * payload area (cf. GetMemoryChunkContext). We simplify matters for this
- * module by requiring sizeof(AllocChunkData) to be maxaligned, and then
- * we can ensure things work by adding any required alignment padding before
- * the "aset" field. There is a static assertion below that the alignment
- * is done correctly.
- */
-typedef struct AllocChunkData
-{
- /* size is always the size of the usable space in the chunk */
- Size size;
-#ifdef MEMORY_CONTEXT_CHECKING
- /* when debugging memory usage, also store actual requested size */
- /* this is zero in a free chunk */
- Size requested_size;
-
-#define ALLOCCHUNK_RAWSIZE (SIZEOF_SIZE_T * 2 + SIZEOF_VOID_P)
-#else
-#define ALLOCCHUNK_RAWSIZE (SIZEOF_SIZE_T + SIZEOF_VOID_P)
-#endif /* MEMORY_CONTEXT_CHECKING */
-
- /* ensure proper alignment by adding padding if needed */
-#if (ALLOCCHUNK_RAWSIZE % MAXIMUM_ALIGNOF) != 0
- char padding[MAXIMUM_ALIGNOF - ALLOCCHUNK_RAWSIZE % MAXIMUM_ALIGNOF];
-#endif
-
- /* aset is the owning aset if allocated, or the freelist link if free */
- void *aset;
- /* there must not be any padding to reach a MAXALIGN boundary here! */
-} AllocChunkData;
-
-/*
- * Only the "aset" field should be accessed outside this module.
+ * Only the "hdrmask" field should be accessed outside this module.
* We keep the rest of an allocated chunk's header marked NOACCESS when using
* valgrind. But note that chunk headers that are in a freelist are kept
* accessible, for simplicity.
*/
-#define ALLOCCHUNK_PRIVATE_LEN offsetof(AllocChunkData, aset)
+#define ALLOCCHUNK_PRIVATE_LEN offsetof(MemoryChunk, hdrmask)
/*
* AllocPointerIsValid
*/
#define AllocSetIsValid(set) PointerIsValid(set)
-#define AllocPointerGetChunk(ptr) \
- ((AllocChunk)(((char *)(ptr)) - ALLOC_CHUNKHDRSZ))
-#define AllocChunkGetPointer(chk) \
- ((AllocPointer)(((char *)(chk)) + ALLOC_CHUNKHDRSZ))
+/*
+ * We always store external chunks on a dedicated block. This makes fetching
+ * the block from an external chunk easy since it's always the first and only
+ * chunk on the block.
+ */
+#define ExternalChunkGetBlock(chunk) \
+ (AllocBlock) ((char *) chunk - ALLOC_BLOCKHDRSZ)
/*
* Rather than repeatedly creating and deleting memory contexts, we keep some
}
};
-/*
- * These functions implement the MemoryContext API for AllocSet contexts.
- */
-static void *AllocSetAlloc(MemoryContext context, Size size);
-static void AllocSetFree(MemoryContext context, void *pointer);
-static void *AllocSetRealloc(MemoryContext context, void *pointer, Size size);
-static void AllocSetReset(MemoryContext context);
-static void AllocSetDelete(MemoryContext context);
-static Size AllocSetGetChunkSpace(MemoryContext context, void *pointer);
-static bool AllocSetIsEmpty(MemoryContext context);
-static void AllocSetStats(MemoryContext context,
- MemoryStatsPrintFunc printfunc, void *passthru,
- MemoryContextCounters *totals,
- bool print_to_stderr);
-
-#ifdef MEMORY_CONTEXT_CHECKING
-static void AllocSetCheck(MemoryContext context);
-#endif
-
-/*
- * This is the virtual function table for AllocSet contexts.
- */
-static const MemoryContextMethods AllocSetMethods = {
- AllocSetAlloc,
- AllocSetFree,
- AllocSetRealloc,
- AllocSetReset,
- AllocSetDelete,
- AllocSetGetChunkSpace,
- AllocSetIsEmpty,
- AllocSetStats
-#ifdef MEMORY_CONTEXT_CHECKING
- ,AllocSetCheck
-#endif
-};
-
/* ----------
* AllocSetFreeIndex -
AllocSet set;
AllocBlock block;
- /* Assert we padded AllocChunkData properly */
+ /* ensure MemoryChunk's size is properly maxaligned */
StaticAssertStmt(ALLOC_CHUNKHDRSZ == MAXALIGN(ALLOC_CHUNKHDRSZ),
- "sizeof(AllocChunkData) is not maxaligned");
- StaticAssertStmt(offsetof(AllocChunkData, aset) + sizeof(MemoryContext) ==
- ALLOC_CHUNKHDRSZ,
- "padding calculation in AllocChunkData is wrong");
+ "sizeof(MemoryChunk) is not maxaligned");
+ /* check we have enough space to store the freelist link */
+ StaticAssertStmt(sizeof(AllocFreeListLink) <= (1 << ALLOC_MINBITS),
+ "sizeof(AllocFreeListLink) larger than minimum allocation size");
/*
* First, validate allocation parameters. Once these were regular runtime
- * test and elog's, but in practice Asserts seem sufficient because nobody
- * varies their parameters at runtime. We somewhat arbitrarily enforce a
- * minimum 1K block size.
+ * tests and elog's, but in practice Asserts seem sufficient because
+ * nobody varies their parameters at runtime. We somewhat arbitrarily
+ * enforce a minimum 1K block size. We restrict the maximum block size to
+ * MEMORYCHUNK_MAX_BLOCKOFFSET as MemoryChunks are limited to this in
+ * regards to addressing the offset between the chunk and the block that
+ * the chunk is stored on. We would be unable to store the offset between
+ * the chunk and block for any chunks that were beyond
+ * MEMORYCHUNK_MAX_BLOCKOFFSET bytes into the block if the block was to be
+ * larger than this.
*/
Assert(initBlockSize == MAXALIGN(initBlockSize) &&
initBlockSize >= 1024);
(minContextSize == MAXALIGN(minContextSize) &&
minContextSize >= 1024 &&
minContextSize <= maxBlockSize));
+ Assert(maxBlockSize <= MEMORYCHUNK_MAX_BLOCKOFFSET);
/*
* Check whether the parameters match either available freelist. We do
/* Reinitialize its header, installing correct name and parent */
MemoryContextCreate((MemoryContext) set,
T_AllocSetContext,
- &AllocSetMethods,
+ MCTX_ASET_ID,
parent,
name);
* requests that are all the maximum chunk size we will waste at most
* 1/8th of the allocated space.
*
- * We have to have allocChunkLimit a power of two, because the requested
- * and actually-allocated sizes of any chunk must be on the same side of
- * the limit, else we get confused about whether the chunk is "big".
- *
* Also, allocChunkLimit must not exceed ALLOCSET_SEPARATE_THRESHOLD.
*/
StaticAssertStmt(ALLOC_CHUNK_LIMIT == ALLOCSET_SEPARATE_THRESHOLD,
"ALLOC_CHUNK_LIMIT != ALLOCSET_SEPARATE_THRESHOLD");
+ /*
+ * Determine the maximum size that a chunk can be before we allocate an
+ * entire AllocBlock dedicated for that chunk. We set the absolute limit
+ * of that size as ALLOC_CHUNK_LIMIT but we reduce it further so that we
+ * can fit about ALLOC_CHUNK_FRACTION chunks this size on a maximally
+ * sized block. (We opt to keep allocChunkLimit a power-of-2 value
+ * primarily for legacy reasons rather than calculating it so that exactly
+ * ALLOC_CHUNK_FRACTION chunks fit on a maximally sized block.)
+ */
set->allocChunkLimit = ALLOC_CHUNK_LIMIT;
while ((Size) (set->allocChunkLimit + ALLOC_CHUNKHDRSZ) >
(Size) ((maxBlockSize - ALLOC_BLOCKHDRSZ) / ALLOC_CHUNK_FRACTION))
/* Finally, do the type-independent part of context creation */
MemoryContextCreate((MemoryContext) set,
T_AllocSetContext,
- &AllocSetMethods,
+ MCTX_ASET_ID,
parent,
name);
* thrash malloc() when a context is repeatedly reset after small allocations,
* which is typical behavior for per-tuple contexts.
*/
-static void
+void
AllocSetReset(MemoryContext context)
{
AllocSet set = (AllocSet) context;
*
* Unlike AllocSetReset, this *must* free all resources of the set.
*/
-static void
+void
AllocSetDelete(MemoryContext context)
{
AllocSet set = (AllocSet) context;
* is marked, as mcxt.c will set it to UNDEFINED. In some paths we will
* return space that is marked NOACCESS - AllocSetRealloc has to beware!
*/
-static void *
+void *
AllocSetAlloc(MemoryContext context, Size size)
{
AllocSet set = (AllocSet) context;
AllocBlock block;
- AllocChunk chunk;
+ MemoryChunk *chunk;
int fidx;
Size chunk_size;
Size blksize;
block->aset = set;
block->freeptr = block->endptr = ((char *) block) + blksize;
- chunk = (AllocChunk) (((char *) block) + ALLOC_BLOCKHDRSZ);
- chunk->aset = set;
- chunk->size = chunk_size;
+ chunk = (MemoryChunk *) (((char *) block) + ALLOC_BLOCKHDRSZ);
+
+ /* mark the MemoryChunk as externally managed */
+ MemoryChunkSetHdrMaskExternal(chunk, MCTX_ASET_ID);
+
#ifdef MEMORY_CONTEXT_CHECKING
chunk->requested_size = size;
/* set mark to catch clobber of "unused" space */
if (size < chunk_size)
- set_sentinel(AllocChunkGetPointer(chunk), size);
+ set_sentinel(MemoryChunkGetPointer(chunk), size);
#endif
#ifdef RANDOMIZE_ALLOCATED_MEMORY
/* fill the allocated space with junk */
- randomize_mem((char *) AllocChunkGetPointer(chunk), size);
+ randomize_mem((char *) MemoryChunkGetPointer(chunk), size);
#endif
/*
}
/* Ensure any padding bytes are marked NOACCESS. */
- VALGRIND_MAKE_MEM_NOACCESS((char *) AllocChunkGetPointer(chunk) + size,
+ VALGRIND_MAKE_MEM_NOACCESS((char *) MemoryChunkGetPointer(chunk) + size,
chunk_size - size);
/* Disallow external access to private part of chunk header. */
VALGRIND_MAKE_MEM_NOACCESS(chunk, ALLOCCHUNK_PRIVATE_LEN);
- return AllocChunkGetPointer(chunk);
+ return MemoryChunkGetPointer(chunk);
}
/*
chunk = set->freelist[fidx];
if (chunk != NULL)
{
- Assert(chunk->size >= size);
+ AllocFreeListLink *link = GetFreeListLink(chunk);
- set->freelist[fidx] = (AllocChunk) chunk->aset;
+ Assert(fidx == MemoryChunkGetValue(chunk));
- chunk->aset = (void *) set;
+ /* pop this chunk off the freelist */
+ VALGRIND_MAKE_MEM_DEFINED(link, sizeof(AllocFreeListLink));
+ set->freelist[fidx] = link->next;
+ VALGRIND_MAKE_MEM_NOACCESS(link, sizeof(AllocFreeListLink));
#ifdef MEMORY_CONTEXT_CHECKING
chunk->requested_size = size;
/* set mark to catch clobber of "unused" space */
- if (size < chunk->size)
- set_sentinel(AllocChunkGetPointer(chunk), size);
+ if (size < GetChunkSizeFromFreeListIdx(fidx))
+ set_sentinel(MemoryChunkGetPointer(chunk), size);
#endif
#ifdef RANDOMIZE_ALLOCATED_MEMORY
/* fill the allocated space with junk */
- randomize_mem((char *) AllocChunkGetPointer(chunk), size);
+ randomize_mem((char *) MemoryChunkGetPointer(chunk), size);
#endif
/* Ensure any padding bytes are marked NOACCESS. */
- VALGRIND_MAKE_MEM_NOACCESS((char *) AllocChunkGetPointer(chunk) + size,
- chunk->size - size);
+ VALGRIND_MAKE_MEM_NOACCESS((char *) MemoryChunkGetPointer(chunk) + size,
+ GetChunkSizeFromFreeListIdx(fidx) - size);
/* Disallow external access to private part of chunk header. */
VALGRIND_MAKE_MEM_NOACCESS(chunk, ALLOCCHUNK_PRIVATE_LEN);
- return AllocChunkGetPointer(chunk);
+ return MemoryChunkGetPointer(chunk);
}
/*
* Choose the actual chunk size to allocate.
*/
- chunk_size = (1 << ALLOC_MINBITS) << fidx;
+ chunk_size = GetChunkSizeFromFreeListIdx(fidx);
Assert(chunk_size >= size);
/*
*/
while (availspace >= ((1 << ALLOC_MINBITS) + ALLOC_CHUNKHDRSZ))
{
+ AllocFreeListLink *link;
Size availchunk = availspace - ALLOC_CHUNKHDRSZ;
int a_fidx = AllocSetFreeIndex(availchunk);
* freelist than the one we need to put this chunk on. The
* exception is when availchunk is exactly a power of 2.
*/
- if (availchunk != ((Size) 1 << (a_fidx + ALLOC_MINBITS)))
+ if (availchunk != GetChunkSizeFromFreeListIdx(a_fidx))
{
a_fidx--;
Assert(a_fidx >= 0);
- availchunk = ((Size) 1 << (a_fidx + ALLOC_MINBITS));
+ availchunk = GetChunkSizeFromFreeListIdx(a_fidx);
}
- chunk = (AllocChunk) (block->freeptr);
+ chunk = (MemoryChunk *) (block->freeptr);
/* Prepare to initialize the chunk header. */
VALGRIND_MAKE_MEM_UNDEFINED(chunk, ALLOC_CHUNKHDRSZ);
-
block->freeptr += (availchunk + ALLOC_CHUNKHDRSZ);
availspace -= (availchunk + ALLOC_CHUNKHDRSZ);
- chunk->size = availchunk;
+ /* store the freelist index in the value field */
+ MemoryChunkSetHdrMask(chunk, block, a_fidx, MCTX_ASET_ID);
#ifdef MEMORY_CONTEXT_CHECKING
- chunk->requested_size = 0; /* mark it free */
+ chunk->requested_size = InvalidAllocSize; /* mark it free */
#endif
- chunk->aset = (void *) set->freelist[a_fidx];
+ /* push this chunk onto the free list */
+ link = GetFreeListLink(chunk);
+
+ VALGRIND_MAKE_MEM_DEFINED(link, sizeof(AllocFreeListLink));
+ link->next = set->freelist[a_fidx];
+ VALGRIND_MAKE_MEM_NOACCESS(link, sizeof(AllocFreeListLink));
+
set->freelist[a_fidx] = chunk;
}
-
/* Mark that we need to create a new block */
block = NULL;
}
/*
* OK, do the allocation
*/
- chunk = (AllocChunk) (block->freeptr);
+ chunk = (MemoryChunk *) (block->freeptr);
/* Prepare to initialize the chunk header. */
VALGRIND_MAKE_MEM_UNDEFINED(chunk, ALLOC_CHUNKHDRSZ);
block->freeptr += (chunk_size + ALLOC_CHUNKHDRSZ);
Assert(block->freeptr <= block->endptr);
- chunk->aset = (void *) set;
- chunk->size = chunk_size;
+ /* store the free list index in the value field */
+ MemoryChunkSetHdrMask(chunk, block, fidx, MCTX_ASET_ID);
+
#ifdef MEMORY_CONTEXT_CHECKING
chunk->requested_size = size;
/* set mark to catch clobber of "unused" space */
- if (size < chunk->size)
- set_sentinel(AllocChunkGetPointer(chunk), size);
+ if (size < chunk_size)
+ set_sentinel(MemoryChunkGetPointer(chunk), size);
#endif
#ifdef RANDOMIZE_ALLOCATED_MEMORY
/* fill the allocated space with junk */
- randomize_mem((char *) AllocChunkGetPointer(chunk), size);
+ randomize_mem((char *) MemoryChunkGetPointer(chunk), size);
#endif
/* Ensure any padding bytes are marked NOACCESS. */
- VALGRIND_MAKE_MEM_NOACCESS((char *) AllocChunkGetPointer(chunk) + size,
+ VALGRIND_MAKE_MEM_NOACCESS((char *) MemoryChunkGetPointer(chunk) + size,
chunk_size - size);
/* Disallow external access to private part of chunk header. */
VALGRIND_MAKE_MEM_NOACCESS(chunk, ALLOCCHUNK_PRIVATE_LEN);
- return AllocChunkGetPointer(chunk);
+ return MemoryChunkGetPointer(chunk);
}
/*
* AllocSetFree
* Frees allocated memory; memory is removed from the set.
*/
-static void
-AllocSetFree(MemoryContext context, void *pointer)
+void
+AllocSetFree(void *pointer)
{
- AllocSet set = (AllocSet) context;
- AllocChunk chunk = AllocPointerGetChunk(pointer);
+ AllocSet set;
+ MemoryChunk *chunk = PointerGetMemoryChunk(pointer);
/* Allow access to private part of chunk header. */
VALGRIND_MAKE_MEM_DEFINED(chunk, ALLOCCHUNK_PRIVATE_LEN);
+ if (MemoryChunkIsExternal(chunk))
+ {
+
+ AllocBlock block = ExternalChunkGetBlock(chunk);
+
+ set = block->aset;
+
#ifdef MEMORY_CONTEXT_CHECKING
- /* Test for someone scribbling on unused space in chunk */
- if (chunk->requested_size < chunk->size)
- if (!sentinel_ok(pointer, chunk->requested_size))
- elog(WARNING, "detected write past chunk end in %s %p",
- set->header.name, chunk);
+ {
+ Size chunk_size = block->endptr - (char *) pointer;
+
+ /* Test for someone scribbling on unused space in chunk */
+ if (chunk->requested_size < chunk_size)
+ if (!sentinel_ok(pointer, chunk->requested_size))
+ elog(WARNING, "detected write past chunk end in %s %p",
+ set->header.name, chunk);
+ }
#endif
- if (chunk->size > set->allocChunkLimit)
- {
- /*
- * Big chunks are certain to have been allocated as single-chunk
- * blocks. Just unlink that block and return it to malloc().
- */
- AllocBlock block = (AllocBlock) (((char *) chunk) - ALLOC_BLOCKHDRSZ);
/*
- * Try to verify that we have a sane block pointer: it should
- * reference the correct aset, and freeptr and endptr should point
- * just past the chunk.
+ * Try to verify that we have a sane block pointer, the freeptr should
+ * match the endptr.
*/
- if (block->aset != set ||
- block->freeptr != block->endptr ||
- block->freeptr != ((char *) block) +
- (chunk->size + ALLOC_BLOCKHDRSZ + ALLOC_CHUNKHDRSZ))
+ if (block->freeptr != block->endptr)
elog(ERROR, "could not find block containing chunk %p", chunk);
/* OK, remove block from aset's list and free it */
if (block->next)
block->next->prev = block->prev;
- context->mem_allocated -= block->endptr - ((char *) block);
+ set->header.mem_allocated -= block->endptr - ((char *) block);
#ifdef CLOBBER_FREED_MEMORY
wipe_mem(block, block->freeptr - ((char *) block));
}
else
{
- /* Normal case, put the chunk into appropriate freelist */
- int fidx = AllocSetFreeIndex(chunk->size);
+ int fidx = MemoryChunkGetValue(chunk);
+ AllocBlock block = MemoryChunkGetBlock(chunk);
+ AllocFreeListLink *link = GetFreeListLink(chunk);
- chunk->aset = (void *) set->freelist[fidx];
+ set = block->aset;
+
+#ifdef MEMORY_CONTEXT_CHECKING
+ /* Test for someone scribbling on unused space in chunk */
+ if (chunk->requested_size < GetChunkSizeFromFreeListIdx(fidx))
+ if (!sentinel_ok(pointer, chunk->requested_size))
+ elog(WARNING, "detected write past chunk end in %s %p",
+ set->header.name, chunk);
+#endif
#ifdef CLOBBER_FREED_MEMORY
- wipe_mem(pointer, chunk->size);
+ wipe_mem(pointer, GetChunkSizeFromFreeListIdx(fidx));
#endif
+ /* push this chunk onto the top of the free list */
+ VALGRIND_MAKE_MEM_DEFINED(link, sizeof(AllocFreeListLink));
+ link->next = set->freelist[fidx];
+ VALGRIND_MAKE_MEM_NOACCESS(link, sizeof(AllocFreeListLink));
+ set->freelist[fidx] = chunk;
#ifdef MEMORY_CONTEXT_CHECKING
- /* Reset requested_size to 0 in chunks that are on freelist */
- chunk->requested_size = 0;
+
+ /*
+ * Reset requested_size to InvalidAllocSize in chunks that are on free
+ * list.
+ */
+ chunk->requested_size = InvalidAllocSize;
#endif
- set->freelist[fidx] = chunk;
}
}
* (In principle, we could use VALGRIND_GET_VBITS() to rediscover the old
* request size.)
*/
-static void *
-AllocSetRealloc(MemoryContext context, void *pointer, Size size)
+void *
+AllocSetRealloc(void *pointer, Size size)
{
- AllocSet set = (AllocSet) context;
- AllocChunk chunk = AllocPointerGetChunk(pointer);
+ AllocBlock block;
+ AllocSet set;
+ MemoryChunk *chunk = PointerGetMemoryChunk(pointer);
Size oldsize;
/* Allow access to private part of chunk header. */
VALGRIND_MAKE_MEM_DEFINED(chunk, ALLOCCHUNK_PRIVATE_LEN);
- oldsize = chunk->size;
-
-#ifdef MEMORY_CONTEXT_CHECKING
- /* Test for someone scribbling on unused space in chunk */
- if (chunk->requested_size < oldsize)
- if (!sentinel_ok(pointer, chunk->requested_size))
- elog(WARNING, "detected write past chunk end in %s %p",
- set->header.name, chunk);
-#endif
-
- if (oldsize > set->allocChunkLimit)
+ if (MemoryChunkIsExternal(chunk))
{
/*
* The chunk must have been allocated as a single-chunk block. Use
* realloc() to make the containing block bigger, or smaller, with
* minimum space wastage.
*/
- AllocBlock block = (AllocBlock) (((char *) chunk) - ALLOC_BLOCKHDRSZ);
Size chksize;
Size blksize;
Size oldblksize;
+ block = ExternalChunkGetBlock(chunk);
+ oldsize = block->endptr - (char *) pointer;
+ set = block->aset;
+
+#ifdef MEMORY_CONTEXT_CHECKING
+ /* Test for someone scribbling on unused space in chunk */
+ if (chunk->requested_size < oldsize)
+ if (!sentinel_ok(pointer, chunk->requested_size))
+ elog(WARNING, "detected write past chunk end in %s %p",
+ set->header.name, chunk);
+#endif
+
/*
- * Try to verify that we have a sane block pointer: it should
- * reference the correct aset, and freeptr and endptr should point
- * just past the chunk.
+ * Try to verify that we have a sane block pointer, the freeptr should
+ * match the endptr.
*/
- if (block->aset != set ||
- block->freeptr != block->endptr ||
- block->freeptr != ((char *) block) +
- (oldsize + ALLOC_BLOCKHDRSZ + ALLOC_CHUNKHDRSZ))
+ if (block->freeptr != block->endptr)
elog(ERROR, "could not find block containing chunk %p", chunk);
- /*
- * Even if the new request is less than set->allocChunkLimit, we stick
- * with the single-chunk block approach. Therefore we need
- * chunk->size to be bigger than set->allocChunkLimit, so we don't get
- * confused about the chunk's status in future calls.
- */
- chksize = Max(size, set->allocChunkLimit + 1);
- chksize = MAXALIGN(chksize);
+ chksize = MAXALIGN(size);
/* Do the realloc */
blksize = chksize + ALLOC_BLOCKHDRSZ + ALLOC_CHUNKHDRSZ;
}
/* updated separately, not to underflow when (oldblksize > blksize) */
- context->mem_allocated -= oldblksize;
- context->mem_allocated += blksize;
+ set->header.mem_allocated -= oldblksize;
+ set->header.mem_allocated += blksize;
block->freeptr = block->endptr = ((char *) block) + blksize;
/* Update pointers since block has likely been moved */
- chunk = (AllocChunk) (((char *) block) + ALLOC_BLOCKHDRSZ);
- pointer = AllocChunkGetPointer(chunk);
+ chunk = (MemoryChunk *) (((char *) block) + ALLOC_BLOCKHDRSZ);
+ pointer = MemoryChunkGetPointer(chunk);
if (block->prev)
block->prev->next = block;
else
set->blocks = block;
if (block->next)
block->next->prev = block;
- chunk->size = chksize;
#ifdef MEMORY_CONTEXT_CHECKING
#ifdef RANDOMIZE_ALLOCATED_MEMORY
#endif
chunk->requested_size = size;
-
/* set mark to catch clobber of "unused" space */
- if (size < chunk->size)
+ if (size < chksize)
set_sentinel(pointer, size);
#else /* !MEMORY_CONTEXT_CHECKING */
return pointer;
}
+ block = MemoryChunkGetBlock(chunk);
+ oldsize = GetChunkSizeFromFreeListIdx(MemoryChunkGetValue(chunk));
+ set = block->aset;
+
+#ifdef MEMORY_CONTEXT_CHECKING
+ /* Test for someone scribbling on unused space in chunk */
+ if (chunk->requested_size < oldsize)
+ if (!sentinel_ok(pointer, chunk->requested_size))
+ elog(WARNING, "detected write past chunk end in %s %p",
+ set->header.name, chunk);
+#endif
+
/*
* Chunk sizes are aligned to power of 2 in AllocSetAlloc(). Maybe the
* allocated area already is >= the new size. (In particular, we will
* fall out here if the requested size is a decrease.)
*/
- else if (oldsize >= size)
+ if (oldsize >= size)
{
#ifdef MEMORY_CONTEXT_CHECKING
Size oldrequest = chunk->requested_size;
memcpy(newPointer, pointer, oldsize);
/* free old chunk */
- AllocSetFree((MemoryContext) set, pointer);
+ AllocSetFree(pointer);
return newPointer;
}
}
+/*
+ * AllocSetGetChunkContext
+ * Return the MemoryContext that 'pointer' belongs to.
+ */
+MemoryContext
+AllocSetGetChunkContext(void *pointer)
+{
+ MemoryChunk *chunk = PointerGetMemoryChunk(pointer);
+ AllocBlock block;
+ AllocSet set;
+
+ if (MemoryChunkIsExternal(chunk))
+ block = ExternalChunkGetBlock(chunk);
+ else
+ block = (AllocBlock) MemoryChunkGetBlock(chunk);
+
+ set = block->aset;
+
+ return &set->header;
+}
+
/*
* AllocSetGetChunkSpace
* Given a currently-allocated chunk, determine the total space
* it occupies (including all memory-allocation overhead).
*/
-static Size
-AllocSetGetChunkSpace(MemoryContext context, void *pointer)
+Size
+AllocSetGetChunkSpace(void *pointer)
{
- AllocChunk chunk = AllocPointerGetChunk(pointer);
- Size result;
+ MemoryChunk *chunk = PointerGetMemoryChunk(pointer);
- VALGRIND_MAKE_MEM_DEFINED(chunk, ALLOCCHUNK_PRIVATE_LEN);
- result = chunk->size + ALLOC_CHUNKHDRSZ;
- VALGRIND_MAKE_MEM_NOACCESS(chunk, ALLOCCHUNK_PRIVATE_LEN);
- return result;
+ if (MemoryChunkIsExternal(chunk))
+ {
+ AllocBlock block = ExternalChunkGetBlock(chunk);
+
+ return block->endptr - (char *) chunk;
+ }
+
+ return GetChunkSizeFromFreeListIdx(MemoryChunkGetValue(chunk)) +
+ ALLOC_CHUNKHDRSZ;
}
/*
* AllocSetIsEmpty
* Is an allocset empty of any allocated space?
*/
-static bool
+bool
AllocSetIsEmpty(MemoryContext context)
{
/*
* totals: if not NULL, add stats about this context into *totals.
* print_to_stderr: print stats to stderr if true, elog otherwise.
*/
-static void
+void
AllocSetStats(MemoryContext context,
MemoryStatsPrintFunc printfunc, void *passthru,
MemoryContextCounters *totals, bool print_to_stderr)
}
for (fidx = 0; fidx < ALLOCSET_NUM_FREELISTS; fidx++)
{
- AllocChunk chunk;
+ MemoryChunk *chunk = set->freelist[fidx];
- for (chunk = set->freelist[fidx]; chunk != NULL;
- chunk = (AllocChunk) chunk->aset)
+ while (chunk != NULL)
{
+ Size chksz = GetChunkSizeFromFreeListIdx(MemoryChunkGetValue(chunk));
+ AllocFreeListLink *link = GetFreeListLink(chunk);
+
+ Assert(GetChunkSizeFromFreeListIdx(fidx) == chksz);
+
freechunks++;
- freespace += chunk->size + ALLOC_CHUNKHDRSZ;
+ freespace += chksz + ALLOC_CHUNKHDRSZ;
+
+ VALGRIND_MAKE_MEM_DEFINED(link, sizeof(AllocFreeListLink));
+ chunk = link->next;
+ VALGRIND_MAKE_MEM_NOACCESS(link, sizeof(AllocFreeListLink));
}
}
* find yourself in an infinite loop when trouble occurs, because this
* routine will be entered again when elog cleanup tries to release memory!
*/
-static void
+void
AllocSetCheck(MemoryContext context)
{
AllocSet set = (AllocSet) context;
long blk_used = block->freeptr - bpoz;
long blk_data = 0;
long nchunks = 0;
+ bool has_external_chunk = false;
if (set->keeper == block)
total_allocated += block->endptr - ((char *) set);
*/
while (bpoz < block->freeptr)
{
- AllocChunk chunk = (AllocChunk) bpoz;
+ MemoryChunk *chunk = (MemoryChunk *) bpoz;
Size chsize,
dsize;
/* Allow access to private part of chunk header. */
VALGRIND_MAKE_MEM_DEFINED(chunk, ALLOCCHUNK_PRIVATE_LEN);
- chsize = chunk->size; /* aligned chunk size */
+ if (MemoryChunkIsExternal(chunk))
+ {
+ chsize = block->endptr - (char *) MemoryChunkGetPointer(chunk); /* aligned chunk size */
+ has_external_chunk = true;
+
+ /* make sure this chunk consumes the entire block */
+ if (chsize + ALLOC_CHUNKHDRSZ != blk_used)
+ elog(WARNING, "problem in alloc set %s: bad single-chunk %p in block %p",
+ name, chunk, block);
+ }
+ else
+ {
+ chsize = GetChunkSizeFromFreeListIdx(MemoryChunkGetValue(chunk)); /* aligned chunk size */
+
+ /*
+ * Check the stored block offset correctly references this
+ * block.
+ */
+ if (block != MemoryChunkGetBlock(chunk))
+ elog(WARNING, "problem in alloc set %s: bad block offset for chunk %p in block %p",
+ name, chunk, block);
+ }
dsize = chunk->requested_size; /* real data */
- /*
- * Check chunk size
- */
- if (dsize > chsize)
+ /* an allocated chunk's requested size must be <= the chsize */
+ if (dsize != InvalidAllocSize && dsize > chsize)
elog(WARNING, "problem in alloc set %s: req size > alloc size for chunk %p in block %p",
name, chunk, block);
+
+ /* chsize must not be smaller than the first freelist's size */
if (chsize < (1 << ALLOC_MINBITS))
elog(WARNING, "problem in alloc set %s: bad size %zu for chunk %p in block %p",
name, chsize, chunk, block);
- /* single-chunk block? */
- if (chsize > set->allocChunkLimit &&
- chsize + ALLOC_CHUNKHDRSZ != blk_used)
- elog(WARNING, "problem in alloc set %s: bad single-chunk %p in block %p",
- name, chunk, block);
-
- /*
- * If chunk is allocated, check for correct aset pointer. (If it's
- * free, the aset is the freelist pointer, which we can't check as
- * easily...) Note this is an incomplete test, since palloc(0)
- * produces an allocated chunk with requested_size == 0.
- */
- if (dsize > 0 && chunk->aset != (void *) set)
- elog(WARNING, "problem in alloc set %s: bogus aset link in block %p, chunk %p",
- name, block, chunk);
-
/*
* Check for overwrite of padding space in an allocated chunk.
*/
- if (chunk->aset == (void *) set && dsize < chsize &&
+ if (dsize != InvalidAllocSize && dsize < chsize &&
!sentinel_ok(chunk, ALLOC_CHUNKHDRSZ + dsize))
elog(WARNING, "problem in alloc set %s: detected write past chunk end in block %p, chunk %p",
name, block, chunk);
* If chunk is allocated, disallow external access to private part
* of chunk header.
*/
- if (chunk->aset == (void *) set)
+ if (dsize != InvalidAllocSize)
VALGRIND_MAKE_MEM_NOACCESS(chunk, ALLOCCHUNK_PRIVATE_LEN);
blk_data += chsize;
if ((blk_data + (nchunks * ALLOC_CHUNKHDRSZ)) != blk_used)
elog(WARNING, "problem in alloc set %s: found inconsistent memory block %p",
name, block);
+
+ if (has_external_chunk && nchunks > 1)
+ elog(WARNING, "problem in alloc set %s: external chunk on non-dedicated block %p",
+ name, block);
}
Assert(total_allocated == context->mem_allocated);
#include "port/pg_bitutils.h"
#include "utils/memdebug.h"
#include "utils/memutils.h"
+#include "utils/memutils_memorychunk.h"
+#include "utils/memutils_internal.h"
#define Generation_BLOCKHDRSZ MAXALIGN(sizeof(GenerationBlock))
-#define Generation_CHUNKHDRSZ sizeof(GenerationChunk)
+#define Generation_CHUNKHDRSZ sizeof(MemoryChunk)
#define Generation_CHUNK_FRACTION 8
typedef struct GenerationBlock GenerationBlock; /* forward reference */
-typedef struct GenerationChunk GenerationChunk;
typedef void *GenerationPointer;
/*
* GenerationBlock
* GenerationBlock is the unit of memory that is obtained by generation.c
- * from malloc(). It contains zero or more GenerationChunks, which are
- * the units requested by palloc() and freed by pfree(). GenerationChunks
- * cannot be returned to malloc() individually, instead pfree()
- * updates the free counter of the block and when all chunks in a block
- * are free the whole block can be returned to malloc().
+ * from malloc(). It contains zero or more MemoryChunks, which are the
+ * units requested by palloc() and freed by pfree(). MemoryChunks cannot
+ * be returned to malloc() individually, instead pfree() updates the free
+ * counter of the block and when all chunks in a block are free the whole
+ * block can be returned to malloc().
*
* GenerationBlock is the header data for a block --- the usable space
* within the block begins at the next alignment boundary.
struct GenerationBlock
{
dlist_node node; /* doubly-linked list of blocks */
+ GenerationContext *context; /* pointer back to the owning context */
Size blksize; /* allocated size of this block */
int nchunks; /* number of chunks in the block */
int nfree; /* number of free chunks */
};
/*
- * GenerationChunk
- * The prefix of each piece of memory in a GenerationBlock
- *
- * Note: to meet the memory context APIs, the payload area of the chunk must
- * be maxaligned, and the "context" link must be immediately adjacent to the
- * payload area (cf. GetMemoryChunkContext). We simplify matters for this
- * module by requiring sizeof(GenerationChunk) to be maxaligned, and then
- * we can ensure things work by adding any required alignment padding before
- * the pointer fields. There is a static assertion below that the alignment
- * is done correctly.
- */
-struct GenerationChunk
-{
- /* size is always the size of the usable space in the chunk */
- Size size;
-#ifdef MEMORY_CONTEXT_CHECKING
- /* when debugging memory usage, also store actual requested size */
- /* this is zero in a free chunk */
- Size requested_size;
-
-#define GENERATIONCHUNK_RAWSIZE (SIZEOF_SIZE_T * 2 + SIZEOF_VOID_P * 2)
-#else
-#define GENERATIONCHUNK_RAWSIZE (SIZEOF_SIZE_T + SIZEOF_VOID_P * 2)
-#endif /* MEMORY_CONTEXT_CHECKING */
-
- /* ensure proper alignment by adding padding if needed */
-#if (GENERATIONCHUNK_RAWSIZE % MAXIMUM_ALIGNOF) != 0
- char padding[MAXIMUM_ALIGNOF - GENERATIONCHUNK_RAWSIZE % MAXIMUM_ALIGNOF];
-#endif
-
- GenerationBlock *block; /* block owning this chunk */
- GenerationContext *context; /* owning context, or NULL if freed chunk */
- /* there must not be any padding to reach a MAXALIGN boundary here! */
-};
-
-/*
- * Only the "context" field should be accessed outside this module.
+ * Only the "hdrmask" field should be accessed outside this module.
* We keep the rest of an allocated chunk's header marked NOACCESS when using
* valgrind. But note that freed chunk headers are kept accessible, for
* simplicity.
*/
-#define GENERATIONCHUNK_PRIVATE_LEN offsetof(GenerationChunk, context)
-
+#define GENERATIONCHUNK_PRIVATE_LEN offsetof(MemoryChunk, hdrmask)
/*
* GenerationIsValid
* True iff set is valid allocation set.
*/
#define GenerationIsValid(set) PointerIsValid(set)
-#define GenerationPointerGetChunk(ptr) \
- ((GenerationChunk *)(((char *)(ptr)) - Generation_CHUNKHDRSZ))
-#define GenerationChunkGetPointer(chk) \
- ((GenerationPointer *)(((char *)(chk)) + Generation_CHUNKHDRSZ))
+/*
+ * We always store external chunks on a dedicated block. This makes fetching
+ * the block from an external chunk easy since it's always the first and only
+ * chunk on the block.
+ */
+#define ExternalChunkGetBlock(chunk) \
+ (GenerationBlock *) ((char *) chunk - Generation_BLOCKHDRSZ)
/* Inlined helper functions */
-static inline void GenerationBlockInit(GenerationBlock *block, Size blksize);
+static inline void GenerationBlockInit(GenerationContext *context,
+ GenerationBlock *block,
+ Size blksize);
static inline bool GenerationBlockIsEmpty(GenerationBlock *block);
static inline void GenerationBlockMarkEmpty(GenerationBlock *block);
static inline Size GenerationBlockFreeBytes(GenerationBlock *block);
static inline void GenerationBlockFree(GenerationContext *set,
GenerationBlock *block);
-/*
- * These functions implement the MemoryContext API for Generation contexts.
- */
-static void *GenerationAlloc(MemoryContext context, Size size);
-static void GenerationFree(MemoryContext context, void *pointer);
-static void *GenerationRealloc(MemoryContext context, void *pointer, Size size);
-static void GenerationReset(MemoryContext context);
-static void GenerationDelete(MemoryContext context);
-static Size GenerationGetChunkSpace(MemoryContext context, void *pointer);
-static bool GenerationIsEmpty(MemoryContext context);
-static void GenerationStats(MemoryContext context,
- MemoryStatsPrintFunc printfunc, void *passthru,
- MemoryContextCounters *totals,
- bool print_to_stderr);
-
-#ifdef MEMORY_CONTEXT_CHECKING
-static void GenerationCheck(MemoryContext context);
-#endif
-
-/*
- * This is the virtual function table for Generation contexts.
- */
-static const MemoryContextMethods GenerationMethods = {
- GenerationAlloc,
- GenerationFree,
- GenerationRealloc,
- GenerationReset,
- GenerationDelete,
- GenerationGetChunkSpace,
- GenerationIsEmpty,
- GenerationStats
-#ifdef MEMORY_CONTEXT_CHECKING
- ,GenerationCheck
-#endif
-};
-
/*
* Public routines
GenerationContext *set;
GenerationBlock *block;
- /* Assert we padded GenerationChunk properly */
+ /* ensure MemoryChunk's size is properly maxaligned */
StaticAssertStmt(Generation_CHUNKHDRSZ == MAXALIGN(Generation_CHUNKHDRSZ),
- "sizeof(GenerationChunk) is not maxaligned");
- StaticAssertStmt(offsetof(GenerationChunk, context) + sizeof(MemoryContext) ==
- Generation_CHUNKHDRSZ,
- "padding calculation in GenerationChunk is wrong");
+ "sizeof(MemoryChunk) is not maxaligned");
/*
* First, validate allocation parameters. Asserts seem sufficient because
* nobody varies their parameters at runtime. We somewhat arbitrarily
- * enforce a minimum 1K block size.
+ * enforce a minimum 1K block size. We restrict the maximum block size to
+ * MEMORYCHUNK_MAX_BLOCKOFFSET as MemoryChunks are limited to this in
+ * regards to addressing the offset between the chunk and the block that
+ * the chunk is stored on. We would be unable to store the offset between
+ * the chunk and block for any chunks that were beyond
+ * MEMORYCHUNK_MAX_BLOCKOFFSET bytes into the block if the block was to be
+ * larger than this.
*/
Assert(initBlockSize == MAXALIGN(initBlockSize) &&
initBlockSize >= 1024);
(minContextSize == MAXALIGN(minContextSize) &&
minContextSize >= 1024 &&
minContextSize <= maxBlockSize));
+ Assert(maxBlockSize <= MEMORYCHUNK_MAX_BLOCKOFFSET);
/* Determine size of initial block */
allocSize = MAXALIGN(sizeof(GenerationContext)) +
block = (GenerationBlock *) (((char *) set) + MAXALIGN(sizeof(GenerationContext)));
/* determine the block size and initialize it */
firstBlockSize = allocSize - MAXALIGN(sizeof(GenerationContext));
- GenerationBlockInit(block, firstBlockSize);
+ GenerationBlockInit(set, block, firstBlockSize);
/* add it to the doubly-linked list of blocks */
dlist_push_head(&set->blocks, &block->node);
/*
* Compute the allocation chunk size limit for this context.
*
- * Follows similar ideas as AllocSet, see aset.c for details ...
+ * Limit the maximum size a non-dedicated chunk can be so that we can fit
+ * at least Generation_CHUNK_FRACTION of chunks this big onto the maximum
+ * sized block. We must further limit this value so that it's no more
+ * than MEMORYCHUNK_MAX_VALUE. We're unable to have non-external chunks
+ * larger than that value as we store the chunk size in the MemoryChunk
+ * 'value' field in the call to MemoryChunkSetHdrMask().
*/
- set->allocChunkLimit = maxBlockSize;
+ set->allocChunkLimit = Min(maxBlockSize, MEMORYCHUNK_MAX_VALUE);
while ((Size) (set->allocChunkLimit + Generation_CHUNKHDRSZ) >
(Size) ((Size) (maxBlockSize - Generation_BLOCKHDRSZ) / Generation_CHUNK_FRACTION))
set->allocChunkLimit >>= 1;
/* Finally, do the type-independent part of context creation */
MemoryContextCreate((MemoryContext) set,
T_GenerationContext,
- &GenerationMethods,
+ MCTX_GENERATION_ID,
parent,
name);
* The code simply frees all the blocks in the context - we don't keep any
* keeper blocks or anything like that.
*/
-static void
+void
GenerationReset(MemoryContext context)
{
GenerationContext *set = (GenerationContext *) context;
* GenerationDelete
* Free all memory which is allocated in the given context.
*/
-static void
+void
GenerationDelete(MemoryContext context)
{
/* Reset to release all releasable GenerationBlocks */
* is marked, as mcxt.c will set it to UNDEFINED. In some paths we will
* return space that is marked NOACCESS - GenerationRealloc has to beware!
*/
-static void *
+void *
GenerationAlloc(MemoryContext context, Size size)
{
GenerationContext *set = (GenerationContext *) context;
GenerationBlock *block;
- GenerationChunk *chunk;
+ MemoryChunk *chunk;
Size chunk_size = MAXALIGN(size);
Size required_size = chunk_size + Generation_CHUNKHDRSZ;
context->mem_allocated += blksize;
/* block with a single (used) chunk */
+ block->context = set;
block->blksize = blksize;
block->nchunks = 1;
block->nfree = 0;
/* the block is completely full */
block->freeptr = block->endptr = ((char *) block) + blksize;
- chunk = (GenerationChunk *) (((char *) block) + Generation_BLOCKHDRSZ);
- chunk->block = block;
- chunk->context = set;
- chunk->size = chunk_size;
+ chunk = (MemoryChunk *) (((char *) block) + Generation_BLOCKHDRSZ);
+
+ /* mark the MemoryChunk as externally managed */
+ MemoryChunkSetHdrMaskExternal(chunk, MCTX_GENERATION_ID);
#ifdef MEMORY_CONTEXT_CHECKING
chunk->requested_size = size;
/* set mark to catch clobber of "unused" space */
if (size < chunk_size)
- set_sentinel(GenerationChunkGetPointer(chunk), size);
+ set_sentinel(MemoryChunkGetPointer(chunk), size);
#endif
#ifdef RANDOMIZE_ALLOCATED_MEMORY
/* fill the allocated space with junk */
- randomize_mem((char *) GenerationChunkGetPointer(chunk), size);
+ randomize_mem((char *) MemoryChunkGetPointer(chunk), size);
#endif
/* add the block to the list of allocated blocks */
dlist_push_head(&set->blocks, &block->node);
/* Ensure any padding bytes are marked NOACCESS. */
- VALGRIND_MAKE_MEM_NOACCESS((char *) GenerationChunkGetPointer(chunk) + size,
+ VALGRIND_MAKE_MEM_NOACCESS((char *) MemoryChunkGetPointer(chunk) + size,
chunk_size - size);
/* Disallow external access to private part of chunk header. */
VALGRIND_MAKE_MEM_NOACCESS(chunk, GENERATIONCHUNK_PRIVATE_LEN);
- return GenerationChunkGetPointer(chunk);
+ return MemoryChunkGetPointer(chunk);
}
/*
context->mem_allocated += blksize;
/* initialize the new block */
- GenerationBlockInit(block, blksize);
+ GenerationBlockInit(set, block, blksize);
/* add it to the doubly-linked list of blocks */
dlist_push_head(&set->blocks, &block->node);
Assert(block != NULL);
Assert((block->endptr - block->freeptr) >= Generation_CHUNKHDRSZ + chunk_size);
- chunk = (GenerationChunk *) block->freeptr;
+ chunk = (MemoryChunk *) block->freeptr;
/* Prepare to initialize the chunk header. */
VALGRIND_MAKE_MEM_UNDEFINED(chunk, Generation_CHUNKHDRSZ);
Assert(block->freeptr <= block->endptr);
- chunk->block = block;
- chunk->context = set;
- chunk->size = chunk_size;
-
+ MemoryChunkSetHdrMask(chunk, block, chunk_size, MCTX_GENERATION_ID);
#ifdef MEMORY_CONTEXT_CHECKING
chunk->requested_size = size;
/* set mark to catch clobber of "unused" space */
- if (size < chunk->size)
- set_sentinel(GenerationChunkGetPointer(chunk), size);
+ if (size < chunk_size)
+ set_sentinel(MemoryChunkGetPointer(chunk), size);
#endif
#ifdef RANDOMIZE_ALLOCATED_MEMORY
/* fill the allocated space with junk */
- randomize_mem((char *) GenerationChunkGetPointer(chunk), size);
+ randomize_mem((char *) MemoryChunkGetPointer(chunk), size);
#endif
/* Ensure any padding bytes are marked NOACCESS. */
- VALGRIND_MAKE_MEM_NOACCESS((char *) GenerationChunkGetPointer(chunk) + size,
+ VALGRIND_MAKE_MEM_NOACCESS((char *) MemoryChunkGetPointer(chunk) + size,
chunk_size - size);
/* Disallow external access to private part of chunk header. */
VALGRIND_MAKE_MEM_NOACCESS(chunk, GENERATIONCHUNK_PRIVATE_LEN);
- return GenerationChunkGetPointer(chunk);
+ return MemoryChunkGetPointer(chunk);
}
/*
* mem_allocated field.
*/
static inline void
-GenerationBlockInit(GenerationBlock *block, Size blksize)
+GenerationBlockInit(GenerationContext *context, GenerationBlock *block,
+ Size blksize)
{
+ block->context = context;
block->blksize = blksize;
block->nchunks = 0;
block->nfree = 0;
* Update number of chunks in the block, and if all chunks in the block
* are now free then discard the block.
*/
-static void
-GenerationFree(MemoryContext context, void *pointer)
+void
+GenerationFree(void *pointer)
{
- GenerationContext *set = (GenerationContext *) context;
- GenerationChunk *chunk = GenerationPointerGetChunk(pointer);
+ MemoryChunk *chunk = PointerGetMemoryChunk(pointer);
GenerationBlock *block;
+ GenerationContext *set;
+#if defined(MEMORY_CONTEXT_CHECKING) || defined(CLOBBER_FREED_MEMORY)
+ Size chunksize;
+#endif
+
+ if (MemoryChunkIsExternal(chunk))
+ {
+ block = ExternalChunkGetBlock(chunk);
+#if defined(MEMORY_CONTEXT_CHECKING) || defined(CLOBBER_FREED_MEMORY)
+ chunksize = block->endptr - (char *) pointer;
+#endif
+ }
+ else
+ {
+ block = MemoryChunkGetBlock(chunk);
+#if defined(MEMORY_CONTEXT_CHECKING) || defined(CLOBBER_FREED_MEMORY)
+ chunksize = MemoryChunkGetValue(chunk);
+#endif
+ }
/* Allow access to private part of chunk header. */
VALGRIND_MAKE_MEM_DEFINED(chunk, GENERATIONCHUNK_PRIVATE_LEN);
- block = chunk->block;
-
#ifdef MEMORY_CONTEXT_CHECKING
/* Test for someone scribbling on unused space in chunk */
- if (chunk->requested_size < chunk->size)
+ if (chunk->requested_size < chunksize)
if (!sentinel_ok(pointer, chunk->requested_size))
elog(WARNING, "detected write past chunk end in %s %p",
- ((MemoryContext) set)->name, chunk);
+ ((MemoryContext) block->context)->name, chunk);
#endif
#ifdef CLOBBER_FREED_MEMORY
- wipe_mem(pointer, chunk->size);
+ wipe_mem(pointer, chunksize);
#endif
- /* Reset context to NULL in freed chunks */
- chunk->context = NULL;
-
#ifdef MEMORY_CONTEXT_CHECKING
- /* Reset requested_size to 0 in freed chunks */
- chunk->requested_size = 0;
+ /* Reset requested_size to InvalidAllocSize in freed chunks */
+ chunk->requested_size = InvalidAllocSize;
#endif
block->nfree += 1;
if (block->nfree < block->nchunks)
return;
+ set = block->context;
+
/* Don't try to free the keeper block, just mark it empty */
if (block == set->keeper)
{
*/
dlist_delete(&block->node);
- context->mem_allocated -= block->blksize;
+ set->header.mem_allocated -= block->blksize;
free(block);
}
* and discard the old one. The only exception is when the new size fits
* into the old chunk - in that case we just update chunk header.
*/
-static void *
-GenerationRealloc(MemoryContext context, void *pointer, Size size)
+void *
+GenerationRealloc(void *pointer, Size size)
{
- GenerationContext *set = (GenerationContext *) context;
- GenerationChunk *chunk = GenerationPointerGetChunk(pointer);
+ MemoryChunk *chunk = PointerGetMemoryChunk(pointer);
+ GenerationContext *set;
+ GenerationBlock *block;
GenerationPointer newPointer;
Size oldsize;
/* Allow access to private part of chunk header. */
VALGRIND_MAKE_MEM_DEFINED(chunk, GENERATIONCHUNK_PRIVATE_LEN);
- oldsize = chunk->size;
+ if (MemoryChunkIsExternal(chunk))
+ {
+ block = ExternalChunkGetBlock(chunk);
+ oldsize = block->endptr - (char *) pointer;
+ }
+ else
+ {
+ block = MemoryChunkGetBlock(chunk);
+ oldsize = MemoryChunkGetValue(chunk);
+ }
+
+ set = block->context;
#ifdef MEMORY_CONTEXT_CHECKING
/* Test for someone scribbling on unused space in chunk */
memcpy(newPointer, pointer, oldsize);
/* free old chunk */
- GenerationFree((MemoryContext) set, pointer);
+ GenerationFree(pointer);
return newPointer;
}
+/*
+ * GenerationGetChunkContext
+ * Return the MemoryContext that 'pointer' belongs to.
+ */
+MemoryContext
+GenerationGetChunkContext(void *pointer)
+{
+ MemoryChunk *chunk = PointerGetMemoryChunk(pointer);
+ GenerationBlock *block;
+
+ if (MemoryChunkIsExternal(chunk))
+ block = ExternalChunkGetBlock(chunk);
+ else
+ block = (GenerationBlock *) MemoryChunkGetBlock(chunk);
+
+ return &block->context->header;
+}
+
/*
* GenerationGetChunkSpace
* Given a currently-allocated chunk, determine the total space
* it occupies (including all memory-allocation overhead).
*/
-static Size
-GenerationGetChunkSpace(MemoryContext context, void *pointer)
+Size
+GenerationGetChunkSpace(void *pointer)
{
- GenerationChunk *chunk = GenerationPointerGetChunk(pointer);
- Size result;
+ MemoryChunk *chunk = PointerGetMemoryChunk(pointer);
+ Size chunksize;
- VALGRIND_MAKE_MEM_DEFINED(chunk, GENERATIONCHUNK_PRIVATE_LEN);
- result = chunk->size + Generation_CHUNKHDRSZ;
- VALGRIND_MAKE_MEM_NOACCESS(chunk, GENERATIONCHUNK_PRIVATE_LEN);
- return result;
+ if (MemoryChunkIsExternal(chunk))
+ {
+ GenerationBlock *block = ExternalChunkGetBlock(chunk);
+
+ chunksize = block->endptr - (char *) pointer;
+ }
+ else
+ chunksize = MemoryChunkGetValue(chunk);
+
+ return Generation_CHUNKHDRSZ + chunksize;
}
/*
* GenerationIsEmpty
* Is a GenerationContext empty of any allocated space?
*/
-static bool
+bool
GenerationIsEmpty(MemoryContext context)
{
GenerationContext *set = (GenerationContext *) context;
* XXX freespace only accounts for empty space at the end of the block, not
* space of freed chunks (which is unknown).
*/
-static void
+void
GenerationStats(MemoryContext context,
MemoryStatsPrintFunc printfunc, void *passthru,
MemoryContextCounters *totals, bool print_to_stderr)
* find yourself in an infinite loop when trouble occurs, because this
* routine will be entered again when elog cleanup tries to release memory!
*/
-static void
+void
GenerationCheck(MemoryContext context)
{
GenerationContext *gen = (GenerationContext *) context;
int nfree,
nchunks;
char *ptr;
+ bool has_external_chunk = false;
total_allocated += block->blksize;
elog(WARNING, "problem in Generation %s: number of free chunks %d in block %p exceeds %d allocated",
name, block->nfree, block, block->nchunks);
+ /* check block belongs to the correct context */
+ if (block->context != gen)
+ elog(WARNING, "problem in Generation %s: bogus context link in block %p",
+ name, block);
+
/* Now walk through the chunks and count them. */
nfree = 0;
nchunks = 0;
while (ptr < block->freeptr)
{
- GenerationChunk *chunk = (GenerationChunk *) ptr;
+ MemoryChunk *chunk = (MemoryChunk *) ptr;
+ GenerationBlock *chunkblock;
+ Size chunksize;
/* Allow access to private part of chunk header. */
VALGRIND_MAKE_MEM_DEFINED(chunk, GENERATIONCHUNK_PRIVATE_LEN);
+ if (MemoryChunkIsExternal(chunk))
+ {
+ chunkblock = ExternalChunkGetBlock(chunk);
+ chunksize = block->endptr - (char *) MemoryChunkGetPointer(chunk);
+ has_external_chunk = true;
+ }
+ else
+ {
+ chunkblock = MemoryChunkGetBlock(chunk);
+ chunksize = MemoryChunkGetValue(chunk);
+ }
+
/* move to the next chunk */
- ptr += (chunk->size + Generation_CHUNKHDRSZ);
+ ptr += (chunksize + Generation_CHUNKHDRSZ);
nchunks += 1;
/* chunks have both block and context pointers, so check both */
- if (chunk->block != block)
+ if (chunkblock != block)
elog(WARNING, "problem in Generation %s: bogus block link in block %p, chunk %p",
name, block, chunk);
- /*
- * Check for valid context pointer. Note this is an incomplete
- * test, since palloc(0) produces an allocated chunk with
- * requested_size == 0.
- */
- if ((chunk->requested_size > 0 && chunk->context != gen) ||
- (chunk->context != gen && chunk->context != NULL))
- elog(WARNING, "problem in Generation %s: bogus context link in block %p, chunk %p",
- name, block, chunk);
-
- /* now make sure the chunk size is correct */
- if (chunk->size < chunk->requested_size ||
- chunk->size != MAXALIGN(chunk->size))
- elog(WARNING, "problem in Generation %s: bogus chunk size in block %p, chunk %p",
- name, block, chunk);
/* is chunk allocated? */
- if (chunk->context != NULL)
+ if (chunk->requested_size != InvalidAllocSize)
{
- /* check sentinel, but only in allocated blocks */
- if (chunk->requested_size < chunk->size &&
+ /* now make sure the chunk size is correct */
+ if (chunksize < chunk->requested_size ||
+ chunksize != MAXALIGN(chunksize))
+ elog(WARNING, "problem in Generation %s: bogus chunk size in block %p, chunk %p",
+ name, block, chunk);
+
+ /* check sentinel */
+ if (chunk->requested_size < chunksize &&
!sentinel_ok(chunk, Generation_CHUNKHDRSZ + chunk->requested_size))
elog(WARNING, "problem in Generation %s: detected write past chunk end in block %p, chunk %p",
name, block, chunk);
* If chunk is allocated, disallow external access to private part
* of chunk header.
*/
- if (chunk->context != NULL)
+ if (chunk->requested_size != InvalidAllocSize)
VALGRIND_MAKE_MEM_NOACCESS(chunk, GENERATIONCHUNK_PRIVATE_LEN);
}
if (nfree != block->nfree)
elog(WARNING, "problem in Generation %s: number of free chunks %d in block %p does not match header %d",
name, nfree, block, block->nfree);
+
+ if (has_external_chunk && nchunks > 1)
+ elog(WARNING, "problem in Generation %s: external chunk on non-dedicated block %p",
+ name, block);
+
}
Assert(total_allocated == context->mem_allocated);
#include "utils/fmgrprotos.h"
#include "utils/memdebug.h"
#include "utils/memutils.h"
+#include "utils/memutils_internal.h"
/*****************************************************************************
* GLOBAL MEMORY *
*****************************************************************************/
+static const MemoryContextMethods mcxt_methods[] = {
+ /* aset.c */
+ [MCTX_ASET_ID].alloc = AllocSetAlloc,
+ [MCTX_ASET_ID].free_p = AllocSetFree,
+ [MCTX_ASET_ID].realloc = AllocSetRealloc,
+ [MCTX_ASET_ID].reset = AllocSetReset,
+ [MCTX_ASET_ID].delete_context = AllocSetDelete,
+ [MCTX_ASET_ID].get_chunk_context = AllocSetGetChunkContext,
+ [MCTX_ASET_ID].get_chunk_space = AllocSetGetChunkSpace,
+ [MCTX_ASET_ID].is_empty = AllocSetIsEmpty,
+ [MCTX_ASET_ID].stats = AllocSetStats,
+#ifdef MEMORY_CONTEXT_CHECKING
+ [MCTX_ASET_ID].check = AllocSetCheck,
+#endif
+
+ /* generation.c */
+ [MCTX_GENERATION_ID].alloc = GenerationAlloc,
+ [MCTX_GENERATION_ID].free_p = GenerationFree,
+ [MCTX_GENERATION_ID].realloc = GenerationRealloc,
+ [MCTX_GENERATION_ID].reset = GenerationReset,
+ [MCTX_GENERATION_ID].delete_context = GenerationDelete,
+ [MCTX_GENERATION_ID].get_chunk_context = GenerationGetChunkContext,
+ [MCTX_GENERATION_ID].get_chunk_space = GenerationGetChunkSpace,
+ [MCTX_GENERATION_ID].is_empty = GenerationIsEmpty,
+ [MCTX_GENERATION_ID].stats = GenerationStats,
+#ifdef MEMORY_CONTEXT_CHECKING
+ [MCTX_GENERATION_ID].check = GenerationCheck,
+#endif
+
+ /* slab.c */
+ [MCTX_SLAB_ID].alloc = SlabAlloc,
+ [MCTX_SLAB_ID].free_p = SlabFree,
+ [MCTX_SLAB_ID].realloc = SlabRealloc,
+ [MCTX_SLAB_ID].reset = SlabReset,
+ [MCTX_SLAB_ID].delete_context = SlabDelete,
+ [MCTX_SLAB_ID].get_chunk_context = SlabGetChunkContext,
+ [MCTX_SLAB_ID].get_chunk_space = SlabGetChunkSpace,
+ [MCTX_SLAB_ID].is_empty = SlabIsEmpty,
+ [MCTX_SLAB_ID].stats = SlabStats
+#ifdef MEMORY_CONTEXT_CHECKING
+ ,[MCTX_SLAB_ID].check = SlabCheck
+#endif
+};
+
/*
* CurrentMemoryContext
* Default memory context for allocations.
#define AssertNotInCriticalSection(context) \
Assert(CritSectionCount == 0 || (context)->allowInCritSection)
+/*
+ * Call the given function in the MemoryContextMethods for the memory context
+ * type that 'pointer' belongs to.
+ */
+#define MCXT_METHOD(pointer, method) \
+ mcxt_methods[GetMemoryChunkMethodID(pointer)].method
+
/*****************************************************************************
* EXPORTED ROUTINES *
context->allowInCritSection = allow;
}
+/*
+ * GetMemoryChunkContext
+ * Given a currently-allocated chunk, determine the MemoryContext that
+ * the chunk belongs to.
+ */
+MemoryContext
+GetMemoryChunkContext(void *pointer)
+{
+ return MCXT_METHOD(pointer, get_chunk_context) (pointer);
+}
+
/*
* GetMemoryChunkSpace
* Given a currently-allocated chunk, determine the total space
Size
GetMemoryChunkSpace(void *pointer)
{
- MemoryContext context = GetMemoryChunkContext(pointer);
-
- return context->methods->get_chunk_space(context, pointer);
+ return MCXT_METHOD(pointer, get_chunk_space) (pointer);
}
/*
*
* node: the as-yet-uninitialized common part of the context header node.
* tag: NodeTag code identifying the memory context type.
- * methods: context-type-specific methods (usually statically allocated).
+ * method_id: MemoryContextMethodID of the context-type being created.
* parent: parent context, or NULL if this will be a top-level context.
* name: name of context (must be statically allocated).
*
void
MemoryContextCreate(MemoryContext node,
NodeTag tag,
- const MemoryContextMethods *methods,
+ MemoryContextMethodID method_id,
MemoryContext parent,
const char *name)
{
/* Initialize all standard fields of memory context header */
node->type = tag;
node->isReset = true;
- node->methods = methods;
+ node->methods = &mcxt_methods[method_id];
node->parent = parent;
node->firstchild = NULL;
node->mem_allocated = 0;
void
pfree(void *pointer)
{
+#ifdef USE_VALGRIND
MemoryContext context = GetMemoryChunkContext(pointer);
+#endif
- context->methods->free_p(context, pointer);
+ MCXT_METHOD(pointer, free_p) (pointer);
VALGRIND_MEMPOOL_FREE(context, pointer);
}
void *
repalloc(void *pointer, Size size)
{
+#if defined(USE_ASSERT_CHECKING) || defined(USE_VALGRIND)
MemoryContext context = GetMemoryChunkContext(pointer);
+#endif
void *ret;
if (!AllocSizeIsValid(size))
/* isReset must be false already */
Assert(!context->isReset);
- ret = context->methods->realloc(context, pointer, size);
+ ret = MCXT_METHOD(pointer, realloc) (pointer, size);
if (unlikely(ret == NULL))
{
+ MemoryContext cxt = GetMemoryChunkContext(pointer);
+
MemoryContextStats(TopMemoryContext);
ereport(ERROR,
(errcode(ERRCODE_OUT_OF_MEMORY),
errmsg("out of memory"),
errdetail("Failed on request of size %zu in memory context \"%s\".",
- size, context->name)));
+ size, cxt->name)));
}
VALGRIND_MEMPOOL_CHANGE(context, pointer, ret, size);
void *
repalloc_huge(void *pointer, Size size)
{
+#if defined(USE_ASSERT_CHECKING) || defined(USE_VALGRIND)
MemoryContext context = GetMemoryChunkContext(pointer);
+#endif
void *ret;
if (!AllocHugeSizeIsValid(size))
/* isReset must be false already */
Assert(!context->isReset);
- ret = context->methods->realloc(context, pointer, size);
+ ret = MCXT_METHOD(pointer, realloc) (pointer, size);
if (unlikely(ret == NULL))
{
+ MemoryContext cxt = GetMemoryChunkContext(pointer);
+
MemoryContextStats(TopMemoryContext);
ereport(ERROR,
(errcode(ERRCODE_OUT_OF_MEMORY),
errmsg("out of memory"),
errdetail("Failed on request of size %zu in memory context \"%s\".",
- size, context->name)));
+ size, cxt->name)));
}
VALGRIND_MEMPOOL_CHANGE(context, pointer, ret, size);
#include "lib/ilist.h"
#include "utils/memdebug.h"
#include "utils/memutils.h"
+#include "utils/memutils_memorychunk.h"
+#include "utils/memutils_internal.h"
/*
* SlabContext is a specialized implementation of MemoryContext.
dlist_node node; /* doubly-linked list */
int nfree; /* number of free chunks */
int firstFreeChunk; /* index of the first free chunk in the block */
-} SlabBlock;
-
-/*
- * SlabChunk
- * The prefix of each piece of memory in a SlabBlock
- *
- * Note: to meet the memory context APIs, the payload area of the chunk must
- * be maxaligned, and the "slab" link must be immediately adjacent to the
- * payload area (cf. GetMemoryChunkContext). Since we support no machines on
- * which MAXALIGN is more than twice sizeof(void *), this happens without any
- * special hacking in this struct declaration. But there is a static
- * assertion below that the alignment is done correctly.
- */
-typedef struct SlabChunk
-{
- SlabBlock *block; /* block owning this chunk */
SlabContext *slab; /* owning context */
- /* there must not be any padding to reach a MAXALIGN boundary here! */
-} SlabChunk;
+} SlabBlock;
+#define Slab_CHUNKHDRSZ sizeof(MemoryChunk)
#define SlabPointerGetChunk(ptr) \
- ((SlabChunk *)(((char *)(ptr)) - sizeof(SlabChunk)))
+ ((MemoryChunk *)(((char *)(ptr)) - sizeof(MemoryChunk)))
#define SlabChunkGetPointer(chk) \
- ((void *)(((char *)(chk)) + sizeof(SlabChunk)))
+ ((void *)(((char *)(chk)) + sizeof(MemoryChunk)))
#define SlabBlockGetChunk(slab, block, idx) \
- ((SlabChunk *) ((char *) (block) + sizeof(SlabBlock) \
+ ((MemoryChunk *) ((char *) (block) + sizeof(SlabBlock) \
+ (idx * slab->fullChunkSize)))
#define SlabBlockStart(block) \
((char *) block + sizeof(SlabBlock))
#define SlabChunkIndex(slab, block, chunk) \
(((char *) chunk - SlabBlockStart(block)) / slab->fullChunkSize)
-/*
- * These functions implement the MemoryContext API for Slab contexts.
- */
-static void *SlabAlloc(MemoryContext context, Size size);
-static void SlabFree(MemoryContext context, void *pointer);
-static void *SlabRealloc(MemoryContext context, void *pointer, Size size);
-static void SlabReset(MemoryContext context);
-static void SlabDelete(MemoryContext context);
-static Size SlabGetChunkSpace(MemoryContext context, void *pointer);
-static bool SlabIsEmpty(MemoryContext context);
-static void SlabStats(MemoryContext context,
- MemoryStatsPrintFunc printfunc, void *passthru,
- MemoryContextCounters *totals,
- bool print_to_stderr);
-#ifdef MEMORY_CONTEXT_CHECKING
-static void SlabCheck(MemoryContext context);
-#endif
-
-/*
- * This is the virtual function table for Slab contexts.
- */
-static const MemoryContextMethods SlabMethods = {
- SlabAlloc,
- SlabFree,
- SlabRealloc,
- SlabReset,
- SlabDelete,
- SlabGetChunkSpace,
- SlabIsEmpty,
- SlabStats
-#ifdef MEMORY_CONTEXT_CHECKING
- ,SlabCheck
-#endif
-};
-
-
/*
* SlabContextCreate
* Create a new Slab context.
* blockSize: allocation block size
* chunkSize: allocation chunk size
*
- * The chunkSize may not exceed:
- * MAXALIGN_DOWN(SIZE_MAX) - MAXALIGN(sizeof(SlabBlock)) - sizeof(SlabChunk)
+ * The MAXALIGN(chunkSize) may not exceed MEMORYCHUNK_MAX_VALUE
*/
MemoryContext
SlabContextCreate(MemoryContext parent,
SlabContext *slab;
int i;
- /* Assert we padded SlabChunk properly */
- StaticAssertStmt(sizeof(SlabChunk) == MAXALIGN(sizeof(SlabChunk)),
- "sizeof(SlabChunk) is not maxaligned");
- StaticAssertStmt(offsetof(SlabChunk, slab) + sizeof(MemoryContext) ==
- sizeof(SlabChunk),
- "padding calculation in SlabChunk is wrong");
+ /* ensure MemoryChunk's size is properly maxaligned */
+ StaticAssertStmt(Slab_CHUNKHDRSZ == MAXALIGN(Slab_CHUNKHDRSZ),
+ "sizeof(MemoryChunk) is not maxaligned");
+ Assert(MAXALIGN(chunkSize) <= MEMORYCHUNK_MAX_VALUE);
/* Make sure the linked list node fits inside a freed chunk */
if (chunkSize < sizeof(int))
chunkSize = sizeof(int);
/* chunk, including SLAB header (both addresses nicely aligned) */
- fullChunkSize = sizeof(SlabChunk) + MAXALIGN(chunkSize);
+ fullChunkSize = Slab_CHUNKHDRSZ + MAXALIGN(chunkSize);
/* Make sure the block can store at least one chunk. */
if (blockSize < fullChunkSize + sizeof(SlabBlock))
/* Finally, do the type-independent part of context creation */
MemoryContextCreate((MemoryContext) slab,
T_SlabContext,
- &SlabMethods,
+ MCTX_SLAB_ID,
parent,
name);
* The code simply frees all the blocks in the context - we don't keep any
* keeper blocks or anything like that.
*/
-static void
+void
SlabReset(MemoryContext context)
{
int i;
* SlabDelete
* Free all memory which is allocated in the given context.
*/
-static void
+void
SlabDelete(MemoryContext context)
{
/* Reset to release all the SlabBlocks */
* Returns pointer to allocated memory of given size or NULL if
* request could not be completed; memory is added to the slab.
*/
-static void *
+void *
SlabAlloc(MemoryContext context, Size size)
{
SlabContext *slab = castNode(SlabContext, context);
SlabBlock *block;
- SlabChunk *chunk;
+ MemoryChunk *chunk;
int idx;
Assert(slab);
block->nfree = slab->chunksPerBlock;
block->firstFreeChunk = 0;
+ block->slab = slab;
/*
* Put all the chunks on a freelist. Walk the chunks and point each
for (idx = 0; idx < slab->chunksPerBlock; idx++)
{
chunk = SlabBlockGetChunk(slab, block, idx);
- *(int32 *) SlabChunkGetPointer(chunk) = (idx + 1);
+ *(int32 *) MemoryChunkGetPointer(chunk) = (idx + 1);
}
/*
* Remove the chunk from the freelist head. The index of the next free
* chunk is stored in the chunk itself.
*/
- VALGRIND_MAKE_MEM_DEFINED(SlabChunkGetPointer(chunk), sizeof(int32));
- block->firstFreeChunk = *(int32 *) SlabChunkGetPointer(chunk);
+ VALGRIND_MAKE_MEM_DEFINED(MemoryChunkGetPointer(chunk), sizeof(int32));
+ block->firstFreeChunk = *(int32 *) MemoryChunkGetPointer(chunk);
Assert(block->firstFreeChunk >= 0);
Assert(block->firstFreeChunk <= slab->chunksPerBlock);
slab->minFreeChunks = 0;
/* Prepare to initialize the chunk header. */
- VALGRIND_MAKE_MEM_UNDEFINED(chunk, sizeof(SlabChunk));
-
- chunk->block = block;
- chunk->slab = slab;
+ VALGRIND_MAKE_MEM_UNDEFINED(chunk, Slab_CHUNKHDRSZ);
+ MemoryChunkSetHdrMask(chunk, block, MAXALIGN(slab->chunkSize),
+ MCTX_SLAB_ID);
#ifdef MEMORY_CONTEXT_CHECKING
/* slab mark to catch clobber of "unused" space */
- if (slab->chunkSize < (slab->fullChunkSize - sizeof(SlabChunk)))
+ if (slab->chunkSize < (slab->fullChunkSize - Slab_CHUNKHDRSZ))
{
- set_sentinel(SlabChunkGetPointer(chunk), size);
+ set_sentinel(MemoryChunkGetPointer(chunk), size);
VALGRIND_MAKE_MEM_NOACCESS(((char *) chunk) +
- sizeof(SlabChunk) + slab->chunkSize,
+ Slab_CHUNKHDRSZ + slab->chunkSize,
slab->fullChunkSize -
- (slab->chunkSize + sizeof(SlabChunk)));
+ (slab->chunkSize + Slab_CHUNKHDRSZ));
}
#endif
+
#ifdef RANDOMIZE_ALLOCATED_MEMORY
/* fill the allocated space with junk */
- randomize_mem((char *) SlabChunkGetPointer(chunk), size);
+ randomize_mem((char *) MemoryChunkGetPointer(chunk), size);
#endif
Assert(slab->nblocks * slab->blockSize == context->mem_allocated);
- return SlabChunkGetPointer(chunk);
+ return MemoryChunkGetPointer(chunk);
}
/*
* SlabFree
* Frees allocated memory; memory is removed from the slab.
*/
-static void
-SlabFree(MemoryContext context, void *pointer)
+void
+SlabFree(void *pointer)
{
int idx;
- SlabContext *slab = castNode(SlabContext, context);
- SlabChunk *chunk = SlabPointerGetChunk(pointer);
- SlabBlock *block = chunk->block;
+ MemoryChunk *chunk = PointerGetMemoryChunk(pointer);
+ SlabBlock *block = MemoryChunkGetBlock(chunk);
+ SlabContext *slab = block->slab;
#ifdef MEMORY_CONTEXT_CHECKING
/* Test for someone scribbling on unused space in chunk */
- if (slab->chunkSize < (slab->fullChunkSize - sizeof(SlabChunk)))
+ if (slab->chunkSize < (slab->fullChunkSize - Slab_CHUNKHDRSZ))
if (!sentinel_ok(pointer, slab->chunkSize))
elog(WARNING, "detected write past chunk end in %s %p",
slab->header.name, chunk);
{
free(block);
slab->nblocks--;
- context->mem_allocated -= slab->blockSize;
+ slab->header.mem_allocated -= slab->blockSize;
}
else
dlist_push_head(&slab->freelist[block->nfree], &block->node);
Assert(slab->nblocks >= 0);
- Assert(slab->nblocks * slab->blockSize == context->mem_allocated);
+ Assert(slab->nblocks * slab->blockSize == slab->header.mem_allocated);
}
/*
* rather pointless - Slab is meant for chunks of constant size, and moreover
* realloc is usually used to enlarge the chunk.
*/
-static void *
-SlabRealloc(MemoryContext context, void *pointer, Size size)
+void *
+SlabRealloc(void *pointer, Size size)
{
- SlabContext *slab = castNode(SlabContext, context);
+ MemoryChunk *chunk = PointerGetMemoryChunk(pointer);
+ SlabBlock *block = MemoryChunkGetBlock(chunk);
+ SlabContext *slab = block->slab;
Assert(slab);
-
/* can't do actual realloc with slab, but let's try to be gentle */
if (size == slab->chunkSize)
return pointer;
return NULL; /* keep compiler quiet */
}
+/*
+ * SlabGetChunkContext
+ * Return the MemoryContext that 'pointer' belongs to.
+ */
+MemoryContext
+SlabGetChunkContext(void *pointer)
+{
+ MemoryChunk *chunk = PointerGetMemoryChunk(pointer);
+ SlabBlock *block = MemoryChunkGetBlock(chunk);
+ SlabContext *slab = block->slab;
+
+ Assert(slab != NULL);
+
+ return &slab->header;
+}
+
/*
* SlabGetChunkSpace
* Given a currently-allocated chunk, determine the total space
* it occupies (including all memory-allocation overhead).
*/
-static Size
-SlabGetChunkSpace(MemoryContext context, void *pointer)
+Size
+SlabGetChunkSpace(void *pointer)
{
- SlabContext *slab = castNode(SlabContext, context);
+ MemoryChunk *chunk = PointerGetMemoryChunk(pointer);
+ SlabBlock *block = MemoryChunkGetBlock(chunk);
+ SlabContext *slab = block->slab;
Assert(slab);
* SlabIsEmpty
* Is an Slab empty of any allocated space?
*/
-static bool
+bool
SlabIsEmpty(MemoryContext context)
{
SlabContext *slab = castNode(SlabContext, context);
* totals: if not NULL, add stats about this context into *totals.
* print_to_stderr: print stats to stderr if true, elog otherwise.
*/
-static void
+void
SlabStats(MemoryContext context,
MemoryStatsPrintFunc printfunc, void *passthru,
MemoryContextCounters *totals,
* find yourself in an infinite loop when trouble occurs, because this
* routine will be entered again when elog cleanup tries to release memory!
*/
-static void
+void
SlabCheck(MemoryContext context)
{
int i;
elog(WARNING, "problem in slab %s: number of free chunks %d in block %p does not match freelist %d",
name, block->nfree, block, i);
+ /* make sure the slab pointer correctly points to this context */
+ if (block->slab != slab)
+ elog(WARNING, "problem in slab %s: bogus slab link in block %p",
+ name, block);
+
/* reset the bitmap of free chunks for this block */
memset(slab->freechunks, 0, (slab->chunksPerBlock * sizeof(bool)));
idx = block->firstFreeChunk;
nfree = 0;
while (idx < slab->chunksPerBlock)
{
- SlabChunk *chunk;
+ MemoryChunk *chunk;
/* count the chunk as free, add it to the bitmap */
nfree++;
/* read index of the next free chunk */
chunk = SlabBlockGetChunk(slab, block, idx);
- VALGRIND_MAKE_MEM_DEFINED(SlabChunkGetPointer(chunk), sizeof(int32));
- idx = *(int32 *) SlabChunkGetPointer(chunk);
+ VALGRIND_MAKE_MEM_DEFINED(MemoryChunkGetPointer(chunk), sizeof(int32));
+ idx = *(int32 *) MemoryChunkGetPointer(chunk);
}
for (j = 0; j < slab->chunksPerBlock; j++)
/* non-zero bit in the bitmap means chunk the chunk is used */
if (!slab->freechunks[j])
{
- SlabChunk *chunk = SlabBlockGetChunk(slab, block, j);
-
- /* chunks have both block and slab pointers, so check both */
- if (chunk->block != block)
+ MemoryChunk *chunk = SlabBlockGetChunk(slab, block, j);
+ SlabBlock *chunkblock = (SlabBlock *) MemoryChunkGetBlock(chunk);
+
+ /*
+ * check the chunk's blockoffset correctly points back to
+ * the block
+ */
+ if (chunkblock != block)
elog(WARNING, "problem in slab %s: bogus block link in block %p, chunk %p",
name, block, chunk);
- if (chunk->slab != slab)
- elog(WARNING, "problem in slab %s: bogus slab link in block %p, chunk %p",
- name, block, chunk);
-
/* there might be sentinel (thanks to alignment) */
- if (slab->chunkSize < (slab->fullChunkSize - sizeof(SlabChunk)))
+ if (slab->chunkSize < (slab->fullChunkSize - Slab_CHUNKHDRSZ))
if (!sentinel_ok(chunk, slab->chunkSize))
elog(WARNING, "problem in slab %s: detected write past chunk end in block %p, chunk %p",
name, block, chunk);
{
void *(*alloc) (MemoryContext context, Size size);
/* call this free_p in case someone #define's free() */
- void (*free_p) (MemoryContext context, void *pointer);
- void *(*realloc) (MemoryContext context, void *pointer, Size size);
+ void (*free_p) (void *pointer);
+ void *(*realloc) (void *pointer, Size size);
void (*reset) (MemoryContext context);
void (*delete_context) (MemoryContext context);
- Size (*get_chunk_space) (MemoryContext context, void *pointer);
+ MemoryContext (*get_chunk_context) (void *pointer);
+ Size (*get_chunk_space) (void *pointer);
bool (*is_empty) (MemoryContext context);
void (*stats) (MemoryContext context,
MemoryStatsPrintFunc printfunc, void *passthru,
#define AllocSizeIsValid(size) ((Size) (size) <= MaxAllocSize)
+/* Must be less than SIZE_MAX */
#define MaxAllocHugeSize (SIZE_MAX / 2)
+#define InvalidAllocSize SIZE_MAX
+
#define AllocHugeSizeIsValid(size) ((Size) (size) <= MaxAllocHugeSize)
extern void MemoryContextSetIdentifier(MemoryContext context, const char *id);
extern void MemoryContextSetParent(MemoryContext context,
MemoryContext new_parent);
+extern MemoryContext GetMemoryChunkContext(void *pointer);
extern Size GetMemoryChunkSpace(void *pointer);
extern MemoryContext MemoryContextGetParent(MemoryContext context);
extern bool MemoryContextIsEmpty(MemoryContext context);
#define MemoryContextCopyAndSetIdentifier(cxt, id) \
MemoryContextSetIdentifier(cxt, MemoryContextStrdup(cxt, id))
-/*
- * GetMemoryChunkContext
- * Given a currently-allocated chunk, determine the context
- * it belongs to.
- *
- * All chunks allocated by any memory context manager are required to be
- * preceded by the corresponding MemoryContext stored, without padding, in the
- * preceding sizeof(void*) bytes. A currently-allocated chunk must contain a
- * backpointer to its owning context. The backpointer is used by pfree() and
- * repalloc() to find the context to call.
- */
-#ifndef FRONTEND
-static inline MemoryContext
-GetMemoryChunkContext(void *pointer)
-{
- MemoryContext context;
-
- /*
- * Try to detect bogus pointers handed to us, poorly though we can.
- * Presumably, a pointer that isn't MAXALIGNED isn't pointing at an
- * allocated chunk.
- */
- Assert(pointer != NULL);
- Assert(pointer == (void *) MAXALIGN(pointer));
-
- /*
- * OK, it's probably safe to look at the context.
- */
- context = *(MemoryContext *) (((char *) pointer) - sizeof(void *));
-
- AssertArg(MemoryContextIsValid(context));
-
- return context;
-}
-#endif
-
-/*
- * This routine handles the context-type-independent part of memory
- * context creation. It's intended to be called from context-type-
- * specific creation routines, and noplace else.
- */
-extern void MemoryContextCreate(MemoryContext node,
- NodeTag tag,
- const MemoryContextMethods *methods,
- MemoryContext parent,
- const char *name);
-
extern void HandleLogMemoryContextInterrupt(void);
extern void ProcessLogMemoryContextInterrupt(void);
--- /dev/null
+/*-------------------------------------------------------------------------
+ *
+ * memutils_internal.h
+ * This file contains declarations for memory allocation utility
+ * functions for internal use.
+ *
+ *
+ * Portions Copyright (c) 2022, PostgreSQL Global Development Group
+ * Portions Copyright (c) 1994, Regents of the University of California
+ *
+ * src/include/utils/memutils_internal.h
+ *
+ *-------------------------------------------------------------------------
+ */
+
+#ifndef MEMUTILS_INTERNAL_H
+#define MEMUTILS_INTERNAL_H
+
+#include "utils/memutils.h"
+
+/* These functions implement the MemoryContext API for AllocSet context. */
+extern void *AllocSetAlloc(MemoryContext context, Size size);
+extern void AllocSetFree(void *pointer);
+extern void *AllocSetRealloc(void *pointer, Size size);
+extern void AllocSetReset(MemoryContext context);
+extern void AllocSetDelete(MemoryContext context);
+extern MemoryContext AllocSetGetChunkContext(void *pointer);
+extern Size AllocSetGetChunkSpace(void *pointer);
+extern bool AllocSetIsEmpty(MemoryContext context);
+extern void AllocSetStats(MemoryContext context,
+ MemoryStatsPrintFunc printfunc, void *passthru,
+ MemoryContextCounters *totals,
+ bool print_to_stderr);
+#ifdef MEMORY_CONTEXT_CHECKING
+extern void AllocSetCheck(MemoryContext context);
+#endif
+
+/* These functions implement the MemoryContext API for Generation context. */
+extern void *GenerationAlloc(MemoryContext context, Size size);
+extern void GenerationFree(void *pointer);
+extern void *GenerationRealloc(void *pointer, Size size);
+extern void GenerationReset(MemoryContext context);
+extern void GenerationDelete(MemoryContext context);
+extern MemoryContext GenerationGetChunkContext(void *pointer);
+extern Size GenerationGetChunkSpace(void *pointer);
+extern bool GenerationIsEmpty(MemoryContext context);
+extern void GenerationStats(MemoryContext context,
+ MemoryStatsPrintFunc printfunc, void *passthru,
+ MemoryContextCounters *totals,
+ bool print_to_stderr);
+#ifdef MEMORY_CONTEXT_CHECKING
+extern void GenerationCheck(MemoryContext context);
+#endif
+
+
+/* These functions implement the MemoryContext API for Slab context. */
+extern void *SlabAlloc(MemoryContext context, Size size);
+extern void SlabFree(void *pointer);
+extern void *SlabRealloc(void *pointer, Size size);
+extern void SlabReset(MemoryContext context);
+extern void SlabDelete(MemoryContext context);
+extern MemoryContext SlabGetChunkContext(void *pointer);
+extern Size SlabGetChunkSpace(void *pointer);
+extern bool SlabIsEmpty(MemoryContext context);
+extern void SlabStats(MemoryContext context,
+ MemoryStatsPrintFunc printfunc, void *passthru,
+ MemoryContextCounters *totals,
+ bool print_to_stderr);
+#ifdef MEMORY_CONTEXT_CHECKING
+extern void SlabCheck(MemoryContext context);
+#endif
+
+/*
+ * MemoryContextMethodID
+ * A unique identifier for each MemoryContext implementation which
+ * indicates the index into the mcxt_methods[] array. See mcxt.c.
+ */
+typedef enum MemoryContextMethodID
+{
+ MCTX_ASET_ID,
+ MCTX_GENERATION_ID,
+ MCTX_SLAB_ID,
+} MemoryContextMethodID;
+
+/*
+ * The number of bits that 8-byte memory chunk headers can use to encode the
+ * MemoryContextMethodID.
+ */
+#define MEMORY_CONTEXT_METHODID_BITS 3
+#define MEMORY_CONTEXT_METHODID_MASK \
+ UINT64CONST((1 << MEMORY_CONTEXT_METHODID_BITS) - 1)
+
+/*
+ * This routine handles the context-type-independent part of memory
+ * context creation. It's intended to be called from context-type-
+ * specific creation routines, and noplace else.
+ */
+extern void MemoryContextCreate(MemoryContext node,
+ NodeTag tag,
+ MemoryContextMethodID method_id,
+ MemoryContext parent,
+ const char *name);
+
+/*
+ * GetMemoryChunkMethodID
+ * Return the MemoryContextMethodID from the uint64 chunk header which
+ * directly precedes 'pointer'.
+ */
+static inline MemoryContextMethodID
+GetMemoryChunkMethodID(void *pointer)
+{
+ uint64 header;
+
+ /*
+ * Try to detect bogus pointers handed to us, poorly though we can.
+ * Presumably, a pointer that isn't MAXALIGNED isn't pointing at an
+ * allocated chunk.
+ */
+ Assert(pointer != NULL);
+ Assert(pointer == (void *) MAXALIGN(pointer));
+
+ header = *((uint64 *) ((char *) pointer - sizeof(uint64)));
+
+ return (MemoryContextMethodID) (header & MEMORY_CONTEXT_METHODID_MASK);
+}
+
+#endif /* MEMUTILS_INTERNAL_H */
--- /dev/null
+/*-------------------------------------------------------------------------
+ *
+ * memutils_memorychunk.h
+ * Here we define a struct named MemoryChunk which implementations of
+ * MemoryContexts may use as a header for chunks of memory they allocate.
+ *
+ * MemoryChunk provides a lightweight header that a MemoryContext can use to
+ * store a reference back to the block the which the given chunk is allocated
+ * on and also an additional 30-bits to store another value such as the size
+ * of the allocated chunk.
+ *
+ * Although MemoryChunks are used by each of our MemoryContexts, future
+ * implementations may choose to implement their own method for storing chunk
+ * headers. The only requirement is that the header ends with an 8-byte value
+ * which the least significant 3-bits of are set to the MemoryContextMethodID
+ * of the given context.
+ *
+ * By default, a MemoryChunk is 8 bytes in size, however, when
+ * MEMORY_CONTEXT_CHECKING is defined the header becomes 16 bytes in size due
+ * to the additional requested_size field. The MemoryContext may use this
+ * field for whatever they wish, but it is intended to be used for additional
+ * checks which are only done in MEMORY_CONTEXT_CHECKING builds.
+ *
+ * The MemoryChunk contains a uint64 field named 'hdrmask'. This field is
+ * used to encode 4 separate pieces of information. Starting with the least
+ * significant bits of 'hdrmask', the bit space is reserved as follows:
+ *
+ * 1. 3-bits to indicate the MemoryContextMethodID as defined by
+ * MEMORY_CONTEXT_METHODID_MASK
+ * 2. 1-bit to denote an "external" chunk (see below)
+ * 3. 30-bits reserved for the MemoryContext to use for anything it
+ * requires. Most MemoryContext likely want to store the size of the
+ * chunk here.
+ * 4. 30-bits for the number of bytes that must be subtracted from the chunk
+ * to obtain the address of the block that the chunk is stored on.
+ *
+ * In some cases, for example when memory allocations become large, it's
+ * possible fields 3 and 4 above are not large enough to store the values
+ * required for the chunk. In this case, the MemoryContext can choose to mark
+ * the chunk as "external" by calling the MemoryChunkSetExternal() function.
+ * When this is done, fields 3 and 4 are unavailable for use by the
+ * MemoryContext and it's up to the MemoryContext itself to devise its own
+ * method for getting the reference to the block.
+ *
+ * Interface:
+ *
+ * MemoryChunkSetHdrMask:
+ * Used to set up a non-external MemoryChunk.
+ *
+ * MemoryChunkSetHdrMaskExternal:
+ * Used to set up an externally managed MemoryChunk.
+ *
+ * MemoryChunkIsExternal:
+ * Determine if the given MemoryChunk is externally managed, i.e.
+ * MemoryChunkSetHdrMaskExternal() was called on the chunk.
+ *
+ * MemoryChunkGetValue:
+ * For non-external chunks, return the stored 30-bit value as it was set
+ * in the call to MemoryChunkSetHdrMask().
+ *
+ * MemoryChunkGetBlock:
+ * For non-external chunks, return a pointer to the block as it was set
+ * in the call to MemoryChunkSetHdrMask().
+ *
+ * Also exports:
+ * MEMORYCHUNK_MAX_VALUE
+ * MEMORYCHUNK_MAX_BLOCKOFFSET
+ * PointerGetMemoryChunk
+ * MemoryChunkGetPointer
+ *
+ * Portions Copyright (c) 2022, PostgreSQL Global Development Group
+ * Portions Copyright (c) 1994, Regents of the University of California
+ *
+ * src/include/utils/memutils_memorychunk.h
+ *
+ *-------------------------------------------------------------------------
+ */
+
+#ifndef MEMUTILS_MEMORYCHUNK_H
+#define MEMUTILS_MEMORYCHUNK_H
+
+#include "utils/memutils_internal.h"
+
+ /*
+ * The maximum allowed value that MemoryContexts can store in the value
+ * field. Must be 1 less than a power of 2.
+ */
+#define MEMORYCHUNK_MAX_VALUE UINT64CONST(0x3FFFFFFF)
+
+/*
+ * The maximum distance in bytes that a MemoryChunk can be offset from the
+ * block that is storing the chunk. Must be 1 less than a power of 2.
+ */
+#define MEMORYCHUNK_MAX_BLOCKOFFSET UINT64CONST(0x3FFFFFFF)
+
+/* define the least significant base-0 bit of each portion of the hdrmask */
+#define MEMORYCHUNK_EXTERNAL_BASEBIT MEMORY_CONTEXT_METHODID_BITS
+#define MEMORYCHUNK_VALUE_BASEBIT (MEMORYCHUNK_EXTERNAL_BASEBIT + 1)
+#define MEMORYCHUNK_BLOCKOFFSET_BASEBIT (MEMORYCHUNK_VALUE_BASEBIT + 30)
+
+/*
+ * A magic number for storing in the free bits of an external chunk. This
+ * must mask out the bits used for storing the MemoryContextMethodID and the
+ * external bit.
+ */
+#define MEMORYCHUNK_MAGIC (UINT64CONST(0xB1A8DB858EB6EFBA) >> \
+ MEMORYCHUNK_VALUE_BASEBIT << \
+ MEMORYCHUNK_VALUE_BASEBIT)
+
+typedef struct MemoryChunk
+{
+#ifdef MEMORY_CONTEXT_CHECKING
+ Size requested_size;
+#endif
+
+ /* bitfield for storing details about the chunk */
+ uint64 hdrmask; /* must be last */
+} MemoryChunk;
+
+/* Get the MemoryChunk from the pointer */
+#define PointerGetMemoryChunk(p) \
+ ((MemoryChunk *) ((char *) (p) - sizeof(MemoryChunk)))
+/* Get the pointer from the MemoryChunk */
+#define MemoryChunkGetPointer(c) \
+ ((void *) ((char *) (c) + sizeof(MemoryChunk)))
+
+/* private macros for making the inline functions below more simple */
+#define HdrMaskIsExternal(hdrmask) \
+ ((hdrmask) & (((uint64) 1) << MEMORYCHUNK_EXTERNAL_BASEBIT))
+#define HdrMaskGetValue(hdrmask) \
+ (((hdrmask) >> MEMORYCHUNK_VALUE_BASEBIT) & MEMORYCHUNK_MAX_VALUE)
+
+/*
+ * We should have used up all the bits here, so the compiler is likely to
+ * optimize out the & MEMORYCHUNK_MAX_BLOCKOFFSET.
+ */
+#define HdrMaskBlockOffset(hdrmask) \
+ (((hdrmask) >> MEMORYCHUNK_BLOCKOFFSET_BASEBIT) & MEMORYCHUNK_MAX_BLOCKOFFSET)
+
+/* For external chunks only, check the magic number matches */
+#define HdrMaskCheckMagic(hdrmask) \
+ (MEMORYCHUNK_MAGIC == \
+ ((hdrmask) >> MEMORYCHUNK_VALUE_BASEBIT << MEMORYCHUNK_VALUE_BASEBIT))
+/*
+ * MemoryChunkSetHdrMask
+ * Store the given 'block', 'chunk_size' and 'methodid' in the given
+ * MemoryChunk.
+ *
+ * The number of bytes between 'block' and 'chunk' must be <=
+ * MEMORYCHUNK_MAX_BLOCKOFFSET.
+ * 'value' must be <= MEMORYCHUNK_MAX_VALUE.
+ */
+static inline void
+MemoryChunkSetHdrMask(MemoryChunk *chunk, void *block,
+ Size value, MemoryContextMethodID methodid)
+{
+ Size blockoffset = (char *) chunk - (char *) block;
+
+ Assert((char *) chunk > (char *) block);
+ Assert(blockoffset <= MEMORYCHUNK_MAX_BLOCKOFFSET);
+ Assert(value <= MEMORYCHUNK_MAX_VALUE);
+ Assert(methodid <= MEMORY_CONTEXT_METHODID_MASK);
+
+ chunk->hdrmask = (((uint64) blockoffset) << MEMORYCHUNK_BLOCKOFFSET_BASEBIT) |
+ (((uint64) value) << MEMORYCHUNK_VALUE_BASEBIT) |
+ methodid;
+}
+
+/*
+ * MemoryChunkSetHdrMaskExternal
+ * Set 'chunk' as an externally managed chunk. Here we only record the
+ * MemoryContextMethodID and set the external chunk bit.
+ */
+static inline void
+MemoryChunkSetHdrMaskExternal(MemoryChunk *chunk,
+ MemoryContextMethodID methodid)
+{
+ Assert(methodid <= MEMORY_CONTEXT_METHODID_MASK);
+
+ chunk->hdrmask = MEMORYCHUNK_MAGIC | (((uint64) 1) << MEMORYCHUNK_EXTERNAL_BASEBIT) |
+ methodid;
+}
+
+/*
+ * MemoryChunkIsExternal
+ * Return true if 'chunk' is marked as external.
+ */
+static inline bool
+MemoryChunkIsExternal(MemoryChunk *chunk)
+{
+ /*
+ * External chunks should always store MEMORYCHUNK_MAGIC in the upper
+ * portion of the hdrmask, check that nothing has stomped on that.
+ */
+ Assert(!HdrMaskIsExternal(chunk->hdrmask) ||
+ HdrMaskCheckMagic(chunk->hdrmask));
+
+ return HdrMaskIsExternal(chunk->hdrmask);
+}
+
+/*
+ * MemoryChunkGetValue
+ * For non-external chunks, returns the value field as it was set in
+ * MemoryChunkSetHdrMask.
+ */
+static inline Size
+MemoryChunkGetValue(MemoryChunk *chunk)
+{
+ Assert(!HdrMaskIsExternal(chunk->hdrmask));
+
+ return HdrMaskGetValue(chunk->hdrmask);
+}
+
+/*
+ * MemoryChunkGetBlock
+ * For non-external chunks, returns the pointer to the block as was set
+ * in MemoryChunkSetHdrMask.
+ */
+static inline void *
+MemoryChunkGetBlock(MemoryChunk *chunk)
+{
+ Assert(!HdrMaskIsExternal(chunk->hdrmask));
+
+ return (void *) ((char *) chunk - HdrMaskBlockOffset(chunk->hdrmask));
+}
+
+/* cleanup all internal definitions */
+#undef MEMORYCHUNK_EXTERNAL_BASEBIT
+#undef MEMORYCHUNK_VALUE_BASEBIT
+#undef MEMORYCHUNK_BLOCKOFFSET_BASEBIT
+#undef MEMORYCHUNK_MAGIC
+#undef HdrMaskIsExternal
+#undef HdrMaskGetValue
+#undef HdrMaskBlockOffset
+#undef HdrMaskCheckMagic
+
+#endif /* MEMUTILS_MEMORYCHUNK_H */
AlenState
Alias
AllocBlock
-AllocChunk
+AllocFreeListLink
AllocPointer
AllocSet
AllocSetContext
Gene
GeneratePruningStepsContext
GenerationBlock
-GenerationChunk
GenerationContext
GenerationPointer
GenericCosts
MemoizePath
MemoizeState
MemoizeTuple
+MemoryChunk
MemoryContext
MemoryContextCallback
MemoryContextCallbackFunction
MemoryContextCounters
MemoryContextData
MemoryContextMethods
+MemoryContextMethodID
MemoryStatsPrintFunc
MergeAction
MergeActionState
Size
SkipPages
SlabBlock
-SlabChunk
SlabContext
SlabSlot
SlotNumber
projects / users / gsingh / postgres.git / commitdiff