BroadleafCommerce/QA#1723 - Add a more efficient paging technique that utilizes last id and page size and omits offset

Author: jefffischer

core/broadleaf-framework/src/main/java/org/broadleafcommerce/core/catalog/dao/ProductDao.java

@@ -271,15 +271,30 @@ public interface ProductDao {
      * 
      * It will fetch results in pages. For example, if page = 3 and pageSize = 25, this method would
      * return rows 75-99 from the database.
-     * 
+     *
+     * When possible, it is suggested to use {@link #readAllActiveProducts(Integer, Long)} instead for performance.
+     *
      * @param page - the number of the page to get (0 indexed)
      * @param pageSize - the number of results per page
      * @return a list of active products for the given page
      */
     public List<Product> readAllActiveProducts(int page, int pageSize);
 
     /**
-     * @deprecated Use {@link #readAllActiveProducts(page, pageSize)}
+     * Reads all products from the database that are currently active. This method utilizes efficient
+     * paging to retrieve a subset of records. This approach does not use an offset technique (like {@link #readAllActiveProducts(int, int)},
+     * but rather limits the retrieved records to those greater than the given id and returns a max results of pageSize. This
+     * is more efficient that using an offset, since the database will not have to retrieve all the records from the beginning
+     * of the table and trim the offset.
+     *
+     * @param pageSize the number of results per page
+     * @param lastId the last id from the previous page - can be null if this is the first page request
+     * @return a list of active products for the given page
+     */
+    List<Product> readAllActiveProducts(Integer pageSize, Long lastId);
+
+    /**
+     * @deprecated Use {@link #readAllActiveProducts(int, int)}
      * 
      * @param page - the number of the page to get (0 indexed)
      * @param pageSize - the number of results per page
@@ -297,7 +312,7 @@ public interface ProductDao {
     public Long readCountAllActiveProducts();
 
     /**
-     * @deprecated {@link #readActiveProductCount()}
+     * @deprecated {@link #readCountAllActiveProducts()}
      * 
      * @param currentDate
      * @return the number of currently active products

core/broadleaf-framework/src/main/java/org/broadleafcommerce/core/catalog/dao/ProductDaoImpl.java

@@ -541,6 +541,12 @@ public List<Product> readAllActiveProducts(int page, int pageSize) {
         Date currentDate = DateUtil.getCurrentDateAfterFactoringInDateResolution(cachedDate, currentDateResolution);
         return readAllActiveProductsInternal(page, pageSize, currentDate);
     }
+
+    @Override
+    public List<Product> readAllActiveProducts(Integer pageSize, Long lastId) {
+        Date currentDate = DateUtil.getCurrentDateAfterFactoringInDateResolution(cachedDate, currentDateResolution);
+        return readAllActiveProductsInternal(pageSize, currentDate, lastId);
+    }
 
     @Override
     @Deprecated
@@ -557,6 +563,15 @@ protected List<Product> readAllActiveProductsInternal(int page, int pageSize, Da
 
         return query.setFirstResult(firstResult).setMaxResults(pageSize).getResultList();
     }
+
+    protected List<Product> readAllActiveProductsInternal(Integer pageSize, Date currentDate, Long lastId) {
+        CriteriaQuery<Product> criteria = getCriteriaForActiveProducts(currentDate, lastId);
+        TypedQuery<Product> query = em.createQuery(criteria);
+        query.setHint(QueryHints.HINT_CACHEABLE, true);
+        query.setHint(QueryHints.HINT_CACHE_REGION, "query.Catalog");
+
+        return query.setMaxResults(pageSize).getResultList();
+    }
 
     @Override
     public List<Product> readAllActiveProducts() {
@@ -620,24 +635,31 @@ protected Long readCountAllActiveProductsInternal(Date currentDate) {
     }
 
     protected CriteriaQuery<Product> getCriteriaForActiveProducts(Date currentDate) {
+        return getCriteriaForActiveProducts(currentDate, null);
+    }
+
+    protected CriteriaQuery<Product> getCriteriaForActiveProducts(Date currentDate, Long lastId) {
         // Set up the criteria query that specifies we want to return Products
         CriteriaBuilder builder = em.getCriteriaBuilder();
         CriteriaQuery<Product> criteria = builder.createQuery(Product.class);
-        
+
         // The root of our search is Product
         Root<ProductImpl> product = criteria.from(ProductImpl.class);
-        
+
         // We need to filter on active date on the sku
         Join<Product, Sku> sku = product.join("defaultSku");
         product.fetch("defaultSku");
-        
+
         // Product objects are what we want back
         criteria.select(product);
-        
+
         // Ensure the product is currently active
         List<Predicate> restrictions = new ArrayList<Predicate>();
         attachActiveRestriction(currentDate, product, sku, restrictions);
-        
+        if (lastId != null) {
+            restrictions.add(builder.gt(product.get("id").as(Long.class), lastId));
+        }
+
         // Add the restrictions to the criteria query
         criteria.where(restrictions.toArray(new Predicate[restrictions.size()]));