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reduce duplicate hash computation in json_object_object_add()

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This can be a very considerable performance saver.
This commit is contained in:
Rainer Gerhards
2015-09-22 19:07:30 +02:00
parent ec4879ac5b
commit d8e44dc685
3 changed files with 60 additions and 9 deletions
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43
linkhash.h
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@@ -231,6 +231,20 @@ extern void lh_table_free(struct lh_table *t);
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
*/
extern int lh_table_insert_w_hash(struct lh_table *t, void *k, const void *v, const unsigned long h);
/**
* Lookup a record into the table.
* @param t the table to lookup
@@ -239,6 +253,19 @@ 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
@@ -285,6 +312,22 @@ 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