Allow to avoid NUL-byte management for stringinfos and use in format.c.

In a lot of the places having appendBinaryStringInfo() maintain a
trailing NUL byte wasn't actually meaningful, e.g. when appending an
integer which can contain 0 in one of its bytes.

Removing this yields some small speedup, but more importantly will be
more consistent when providing faster variants of pq_sendint etc.

Author: Andres Freund
Discussion: https://postgr.es/m/20170914063418.sckdzgjfrsbekae4@alap3.anarazel.de

diff --git a/src/backend/lib/stringinfo.c b/src/backend/lib/stringinfo.c
index fd155671443b153f4d43180339b71b65345cdcc1..cb2026c3b20cf4dcd62c11c7b76c5ed00873a8d9 100644 (file)
--- a/src/backend/lib/stringinfo.c
+++ b/src/backend/lib/stringinfo.c
@@ -202,7 +202,7 @@ appendStringInfoSpaces(StringInfo str, int count)
  * appendBinaryStringInfo
  *
  * Append arbitrary binary data to a StringInfo, allocating more space
- * if necessary.
+ * if necessary. Ensures that a trailing null byte is present.
  */
 void
 appendBinaryStringInfo(StringInfo str, const char *data, int datalen)
@@ -224,6 +224,25 @@ appendBinaryStringInfo(StringInfo str, const char *data, int datalen)
    str->data[str->len] = '\0';
 }
 
+/*
+ * appendBinaryStringInfoNT
+ *
+ * Append arbitrary binary data to a StringInfo, allocating more space
+ * if necessary. Does not ensure a trailing null-byte exists.
+ */
+void
+appendBinaryStringInfoNT(StringInfo str, const char *data, int datalen)
+{
+   Assert(str != NULL);
+
+   /* Make more room if needed */
+   enlargeStringInfo(str, datalen);
+
+   /* OK, append the data */
+   memcpy(str->data + str->len, data, datalen);
+   str->len += datalen;
+}
+
 /*
  * enlargeStringInfo
  *

diff --git a/src/backend/libpq/pqformat.c b/src/backend/libpq/pqformat.c
index f27a04f8344e084a3e8a5a091369a0ccdf0a4fbf..2414d0d8e9ae6f180b703fdb743d5b4ab0f2e5fc 100644 (file)
--- a/src/backend/libpq/pqformat.c
+++ b/src/backend/libpq/pqformat.c
@@ -138,13 +138,13 @@ pq_sendcountedtext(StringInfo buf, const char *str, int slen,
    {
        slen = strlen(p);
        pq_sendint(buf, slen + extra, 4);
-       appendBinaryStringInfo(buf, p, slen);
+       appendBinaryStringInfoNT(buf, p, slen);
        pfree(p);
    }
    else
    {
        pq_sendint(buf, slen + extra, 4);
-       appendBinaryStringInfo(buf, str, slen);
+       appendBinaryStringInfoNT(buf, str, slen);
    }
 }
 
@@ -191,11 +191,11 @@ pq_sendstring(StringInfo buf, const char *str)
    if (p != str)               /* actual conversion has been done? */
    {
        slen = strlen(p);
-       appendBinaryStringInfo(buf, p, slen + 1);
+       appendBinaryStringInfoNT(buf, p, slen + 1);
        pfree(p);
    }
    else
-       appendBinaryStringInfo(buf, str, slen + 1);
+       appendBinaryStringInfoNT(buf, str, slen + 1);
 }
 
 /* --------------------------------
@@ -242,15 +242,15 @@ pq_sendint(StringInfo buf, int i, int b)
    {
        case 1:
            n8 = (unsigned char) i;
-           appendBinaryStringInfo(buf, (char *) &n8, 1);
+           appendBinaryStringInfoNT(buf, (char *) &n8, 1);
            break;
        case 2:
            n16 = pg_hton16((uint16) i);
-           appendBinaryStringInfo(buf, (char *) &n16, 2);
+           appendBinaryStringInfoNT(buf, (char *) &n16, 2);
            break;
        case 4:
            n32 = pg_hton32((uint32) i);
-           appendBinaryStringInfo(buf, (char *) &n32, 4);
+           appendBinaryStringInfoNT(buf, (char *) &n32, 4);
            break;
        default:
            elog(ERROR, "unsupported integer size %d", b);
@@ -271,7 +271,7 @@ pq_sendint64(StringInfo buf, int64 i)
 {
    uint64      n64 = pg_hton64(i);
 
-   appendBinaryStringInfo(buf, (char *) &n64, sizeof(n64));
+   appendBinaryStringInfoNT(buf, (char *) &n64, sizeof(n64));
 }
 
 /* --------------------------------
@@ -297,7 +297,7 @@ pq_sendfloat4(StringInfo buf, float4 f)
    swap.f = f;
    swap.i = pg_hton32(swap.i);
 
-   appendBinaryStringInfo(buf, (char *) &swap.i, 4);
+   appendBinaryStringInfoNT(buf, (char *) &swap.i, 4);
 }
 
 /* --------------------------------

diff --git a/src/include/lib/stringinfo.h b/src/include/lib/stringinfo.h
index 9694ea3f2194b7c34f48afe6546ad8266d2a8e71..01b845db44bde36f8b75eb0f721c7570341c34c2 100644 (file)
--- a/src/include/lib/stringinfo.h
+++ b/src/include/lib/stringinfo.h
@@ -143,6 +143,14 @@ extern void appendStringInfoSpaces(StringInfo str, int count);
 extern void appendBinaryStringInfo(StringInfo str,
                       const char *data, int datalen);
 
+/*------------------------
+ * appendBinaryStringInfoNT
+ * Append arbitrary binary data to a StringInfo, allocating more space
+ * if necessary. Does not ensure a trailing null-byte exists.
+ */
+extern void appendBinaryStringInfoNT(StringInfo str,
+                      const char *data, int datalen);
+
 /*------------------------
  * enlargeStringInfo
  * Make sure a StringInfo's buffer can hold at least 'needed' more bytes.