Re: [dpdk-dev] [PATCH v2 08/11] hash: add new functionality to store data in hash table

[Stephen Hemminger <stephen@networkplumber.org>]

We did same thing with a slightly different method.

Subject: rte_hash: split key and bucket size

It is useful to store more data in the has bucket than just the key size.
For example, storing an addresss and additional data.

Signed-off-by: Stephen Hemminger <stephen@networkplumber.org>


--- a/lib/librte_hash/rte_hash.h
+++ b/lib/librte_hash/rte_hash.h
@@ -78,7 +78,8 @@ struct rte_hash_parameters {
 	const char *name;		/**< Name of the hash. */
 	uint32_t entries;		/**< Total hash table entries. */
 	uint32_t bucket_entries;	/**< Bucket entries. */
-	uint32_t key_len;		/**< Length of hash key. */
+	uint16_t key_len;		/**< Length of hash key. */
+	uint16_t cmp_len;		/**< Length of hash key compare (bytes). */
 	rte_hash_function hash_func;	/**< Function used to calculate hash. */
 	uint32_t hash_func_init_val;	/**< Init value used by hash_func. */
 	int socket_id;			/**< NUMA Socket ID for memory. */
@@ -89,7 +90,8 @@ struct rte_hash {
 	char name[RTE_HASH_NAMESIZE];	/**< Name of the hash. */
 	uint32_t entries;		/**< Total table entries. */
 	uint32_t bucket_entries;	/**< Bucket entries. */
-	uint32_t key_len;		/**< Length of hash key. */
+	uint16_t key_len;		/**< Length of hash key. */
+	uint16_t cmp_len;		/**< Length of hash key compare (bytes) */
 	rte_hash_function hash_func;	/**< Function used to calculate hash. */
 	uint32_t hash_func_init_val;	/**< Init value used by hash_func. */
 	uint32_t num_buckets;		/**< Number of buckets in table. */
@@ -240,7 +242,7 @@ rte_hash_del_key_with_hash(const struct
  *     value that was returned when the key was added.
  */
 int32_t
-rte_hash_lookup(const struct rte_hash *h, const void *key);
+rte_hash_lookup(const struct rte_hash *h, void *key);
 
 /**
  * Find a key in the hash table. This operation is multi-thread safe.
@@ -260,7 +262,7 @@ rte_hash_lookup(const struct rte_hash *h
  */
 int32_t
 rte_hash_lookup_with_hash(const struct rte_hash *h,
-				const void *key, hash_sig_t sig);
+			  void *key, hash_sig_t sig);
 
 
 /**
@@ -277,7 +279,7 @@ static inline hash_sig_t
 rte_hash_hash(const struct rte_hash *h, const void *key)
 {
 	/* calc hash result by key */
-	return h->hash_func(key, h->key_len, h->hash_func_init_val);
+	return h->hash_func(key, h->cmp_len, h->hash_func_init_val);
 }
 
 #define rte_hash_lookup_multi rte_hash_lookup_bulk
--- a/lib/librte_hash/rte_hash.c
+++ b/lib/librte_hash/rte_hash.c
@@ -185,7 +185,8 @@ rte_hash_create(const struct rte_hash_pa
 			!rte_is_power_of_2(params->entries) ||
 			!rte_is_power_of_2(params->bucket_entries) ||
 			(params->key_len == 0) ||
-			(params->key_len > RTE_HASH_KEY_LENGTH_MAX)) {
+			(params->key_len > RTE_HASH_KEY_LENGTH_MAX)||
+			(params->cmp_len > params->key_len)) {
 		rte_errno = EINVAL;
 		RTE_LOG(ERR, HASH, "rte_hash_create has invalid parameters\n");
 		return NULL;
@@ -238,6 +239,7 @@ rte_hash_create(const struct rte_hash_pa
 	h->entries = params->entries;
 	h->bucket_entries = params->bucket_entries;
 	h->key_len = params->key_len;
+	h->cmp_len = params->cmp_len ? params->cmp_len : h->key_len;
 	h->hash_func_init_val = params->hash_func_init_val;
 	h->num_buckets = num_buckets;
 	h->bucket_bitmask = h->num_buckets - 1;
@@ -310,7 +312,7 @@ __rte_hash_add_key_with_hash(const struc
 	for (i = 0; i < h->bucket_entries; i++) {
 		if ((sig == sig_bucket[i]) &&
 		    likely(memcmp(key, get_key_from_bucket(h, key_bucket, i),
-				  h->key_len) == 0)) {
+				  h->cmp_len) == 0)) {
 			return bucket_index * h->bucket_entries + i;
 		}
 	}
@@ -360,7 +362,7 @@ __rte_hash_del_key_with_hash(const struc
 	for (i = 0; i < h->bucket_entries; i++) {
 		if ((sig == sig_bucket[i]) &&
 		    likely(memcmp(key, get_key_from_bucket(h, key_bucket, i),
-				  h->key_len) == 0)) {
+				  h->cmp_len) == 0)) {
 			sig_bucket[i] = NULL_SIGNATURE;
 			return bucket_index * h->bucket_entries + i;
 		}
@@ -386,7 +388,7 @@ rte_hash_del_key(const struct rte_hash *
 
 static inline int32_t
 __rte_hash_lookup_with_hash(const struct rte_hash *h,
-			const void *key, hash_sig_t sig)
+			    void *key, hash_sig_t sig)
 {
 	hash_sig_t *sig_bucket;
 	uint8_t *key_bucket;
@@ -402,7 +404,9 @@ __rte_hash_lookup_with_hash(const struct
 	for (i = 0; i < h->bucket_entries; i++) {
 		if ((sig == sig_bucket[i]) &&
 		    likely(memcmp(key, get_key_from_bucket(h, key_bucket, i),
-				  h->key_len) == 0)) {
+				  h->cmp_len) == 0)) {
+		        rte_memcpy(key, get_key_from_bucket(h, key_bucket, i),
+				   h->key_len);
 			return bucket_index * h->bucket_entries + i;
 		}
 	}
@@ -412,14 +416,14 @@ __rte_hash_lookup_with_hash(const struct
 
 int32_t
 rte_hash_lookup_with_hash(const struct rte_hash *h,
-			const void *key, hash_sig_t sig)
+			  void *key, hash_sig_t sig)
 {
 	RETURN_IF_TRUE(((h == NULL) || (key == NULL)), -EINVAL);
 	return __rte_hash_lookup_with_hash(h, key, sig);
 }
 
 int32_t
-rte_hash_lookup(const struct rte_hash *h, const void *key)
+rte_hash_lookup(const struct rte_hash *h, void *key)
 {
 	RETURN_IF_TRUE(((h == NULL) || (key == NULL)), -EINVAL);
 	return __rte_hash_lookup_with_hash(h, key, rte_hash_hash(h, key));
@@ -438,7 +442,7 @@ rte_hash_lookup_bulk(const struct rte_ha
 
 	/* Get the hash signature and bucket index */
 	for (i = 0; i < num_keys; i++) {
-		sigs[i] = h->hash_func(keys[i], h->key_len,
+		sigs[i] = h->hash_func(keys[i], h->cmp_len,
 				h->hash_func_init_val) | h->sig_msb;
 		bucket_index = sigs[i] & h->bucket_bitmask;
 
@@ -459,7 +463,7 @@ rte_hash_lookup_bulk(const struct rte_ha
 			if ((sigs[i] == sig_bucket[j]) &&
 			    likely(memcmp(keys[i],
 					  get_key_from_bucket(h, key_bucket, j),
-					  h->key_len) == 0)) {
+					  h->cmp_len) == 0)) {
 				positions[i] = bucket_index *
 					h->bucket_entries + j;
 				break;