Merge pull request #196 from rgerhards/improve-performance

Performance improvements

1 files changed, 65 insertions, 44 deletions

diff --git a/linkhash.h b/linkhash.h
index 280d64b..c037fef 100644
--- a/linkhash.h
+++ b/linkhash.h
@@ -41,6 +41,23 @@ extern "C" {
  */
 #define LH_FREED (void*)-2
 
+/**
+ * default string hash function
+ */
+#define JSON_C_STR_HASH_DFLT 0
+
+/**
+ * perl-like string hash function
+ */
+#define JSON_C_STR_HASH_PERLLIKE 1
+
+/**
+ * This function sets the hash function to be used for strings.
+ * Must be one of the JSON_C_STR_HASH_* values.
+ * @returns 0 - ok, -1 if parameter was invalid
+ */
+int json_global_set_string_hash(const int h);
+
 struct lh_entry;
 
 /**
@@ -64,6 +81,7 @@ struct lh_entry {
 	 * The key.
 	 */
 	void *k;
+	int k_is_constant;
 	/**
 	 * The value.
 	 */
@@ -93,36 +111,6 @@ struct lh_table {
 	int count;
 
 	/**
-	 * Number of collisions.
-	 */
-	int collisions;
-
-	/**
-	 * Number of resizes.
-	 */
-	int resizes;
-
-	/**
-	 * Number of lookups.
-	 */
-	int lookups;
-
-	/**
-	 * Number of inserts.
-	 */
-	int inserts;
-
-	/**
-	 * Number of deletes.
-	 */
-	int deletes;
-
-	/**
-	 * Name of the hash table.
-	 */
-	const char *name;
-
-	/**
 	 * The first entry.
 	 */
 	struct lh_entry *head;
@@ -144,16 +132,6 @@ struct lh_table {
 
 
 /**
- * Pre-defined hash and equality functions
- */
-extern unsigned long lh_ptr_hash(const void *k);
-extern int lh_ptr_equal(const void *k1, const void *k2);
-
-extern unsigned long lh_char_hash(const void *k);
-extern int lh_char_equal(const void *k1, const void *k2);
-
-
-/**
  * Convenience list iterator.
  */
 #define lh_foreach(table, entry) \
@@ -171,7 +149,6 @@ for(entry = table->head; entry && ((tmp = entry->next) || 1); entry = tmp)
  * Create a new linkhash table.
  * @param size initial table size. The table is automatically resized
  * although this incurs a performance penalty.
- * @param name the table name.
  * @param free_fn callback function used to free memory for entries
  * when lh_table_free or lh_table_delete is called.
  * If NULL is provided, then memory for keys and values
@@ -184,7 +161,7 @@ for(entry = table->head; entry && ((tmp = entry->next) || 1); entry = tmp)
  * and C strings respectively.
  * @return a pointer onto the linkhash table.
  */
-extern struct lh_table* lh_table_new(int size, const char *name,
+extern struct lh_table* lh_table_new(int size,
 				     lh_entry_free_fn *free_fn,
 				     lh_hash_fn *hash_fn,
 				     lh_equal_fn *equal_fn);
@@ -197,7 +174,7 @@ extern struct lh_table* lh_table_new(int size, const char *name,
  * @param free_fn callback function used to free memory for entries.
  * @return a pointer onto the linkhash table.
  */
-extern struct lh_table* lh_kchar_table_new(int size, const char *name,
+extern struct lh_table* lh_kchar_table_new(int size,
 					   lh_entry_free_fn *free_fn);
 
 
@@ -209,7 +186,7 @@ extern struct lh_table* lh_kchar_table_new(int size, const char *name,
  * @param free_fn callback function used to free memory for entries.
  * @return a pointer onto the linkhash table.
  */
-extern struct lh_table* lh_kptr_table_new(int size, const char *name,
+extern struct lh_table* lh_kptr_table_new(int size,
 					  lh_entry_free_fn *free_fn);
 
 
@@ -232,6 +209,21 @@ extern int lh_table_insert(struct lh_table *t, void *k, const void *v);
 
 
 /**
+ * Insert a record into the table. This one accepts the key's hash in additon
+ * to the key. This is an exension to support functions that need to calculate
+ * the hash several times and allows them to do it just once and then pass
+ * in the hash to all utility functions. Depending on use case, this can be a 
+ * very considerate performance improvement.
+ * @param t the table to insert into.
+ * @param k a pointer to the key to insert.
+ * @param v a pointer to the value to insert.
+ * @param h hash value of the key to insert
+ * @param opts opts, a subset of JSON_OBJECT_ADD_* flags is supported
+ */
+extern int lh_table_insert_w_hash(struct lh_table *t, void *k, const void *v, const unsigned long h, const unsigned opts);
+
+
+/**
  * Lookup a record into the table.
  * @param t the table to lookup
  * @param k a pointer to the key to lookup
@@ -240,6 +232,19 @@ extern int lh_table_insert(struct lh_table *t, void *k, const void *v);
 extern struct lh_entry* lh_table_lookup_entry(struct lh_table *t, const void *k);
 
 /**
+ * Lookup a record into the table. This one accepts the key's hash in additon
+ * to the key. This is an exension to support functions that need to calculate
+ * the hash several times and allows them to do it just once and then pass
+ * in the hash to all utility functions. Depending on use case, this can be a 
+ * very considerate performance improvement.
+ * @param t the table to lookup
+ * @param k a pointer to the key to lookup
+ * @param h hash value of the key to lookup
+ * @return a pointer to the record structure of the value or NULL if it does not exist.
+ */
+extern struct lh_entry* lh_table_lookup_entry_w_hash(struct lh_table *t, const void *k, const unsigned long h);
+
+/**
  * Lookup a record into the table
  * @param t the table to lookup
  * @param k a pointer to the key to lookup
@@ -285,6 +290,22 @@ extern int lh_table_length(struct lh_table *t);
 void lh_abort(const char *msg, ...);
 void lh_table_resize(struct lh_table *t, int new_size);
 
+
+/**
+ * Calculate the hash of a key for a given table.
+ * This is an exension to support functions that need to calculate
+ * the hash several times and allows them to do it just once and then pass
+ * in the hash to all utility functions. Depending on use case, this can be a 
+ * very considerate performance improvement.
+ * @param t the table (used to obtain hash function)
+ * @param k a pointer to the key to lookup
+ * @return the key's hash
+ */
+static inline unsigned long lh_get_hash(const struct lh_table *t, const void *k)
+{
+	return t->hash_fn(k);
+}
+
 #ifdef __cplusplus
 }
 #endif