src/vppinfra/cuckoo_template.h - fdio/vpp - Gitiles

 /*
   Copyright (c) 2017 Cisco and/or its affiliates.

   * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
  * You may obtain a copy of the License at:
  *
  *     http://www.apache.org/licenses/LICENSE-2.0
  *
  * Unless required by applicable law or agreed to in writing, software
  * distributed under the License is distributed on an "AS IS" BASIS,
  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  * See the License for the specific language governing permissions and
  * limitations under the License.
 */

 /*
  * cuckoo hash implementation based on paper
  * 'Algorithmic Improvements for Fast Concurrent Cuckoo Hashing'
  * by Xiaozhou Li, David G. Andersen, Michael Kaminsky, Michael J. Freedman
  * and their libcuckoo implementation (https://github.com/efficient/libcuckoo)
  */

 /*
  * Note: to instantiate the template multiple times in a single file,
  * #undef __included_cuckoo_template_h__...
  */
 #ifndef __included_cuckoo_template_h__
 #define __included_cuckoo_template_h__

 #include <vppinfra/heap.h>
 #include <vppinfra/format.h>
 #include <vppinfra/pool.h>
 #include <vppinfra/lock.h>
 #include <vppinfra/error.h>
 #include <vppinfra/hash.h>
 #include <vppinfra/cache.h>

 #ifndef CLIB_CUCKOO_TYPE
 #error CLIB_CUCKOO_TYPE not defined
 #endif

 #ifndef CLIB_CUCKOO_BFS_MAX_STEPS
 #error CLIB_CUCKOO_BFS_MAX_STEPS not defined
 #endif

 #ifndef CLIB_CUCKOO_KVP_PER_BUCKET
 #error CLIB_CUCKOO_KVP_PER_BUCKET not defined
 #endif

 #ifndef CLIB_CUCKOO_LOG2_KVP_PER_BUCKET
 #error CLIB_CUCKOO_LOG2_KVP_PER_BUCKET not defined
 #endif

 #ifndef CLIB_CUCKOO_BFS_MAX_PATH_LENGTH
 #error CLIB_CUCKOO_BFS_MAX_PATH_LENGTH not defined
 #endif

 STATIC_ASSERT (CLIB_CUCKOO_KVP_PER_BUCKET ==
 	       (1 << CLIB_CUCKOO_LOG2_KVP_PER_BUCKET),
 	       "CLIB_CUCKOO_KVP_PER_BUCKET != (1 << CLIB_CUCKOO_LOG2_KVP_PER_BUCKET");

 #define _cv(a, b) a##b
 #define __cv(a, b) _cv (a, b)
 #define CV(a) __cv (a, CLIB_CUCKOO_TYPE)

 #define _cvt(a, b) a##b##_t
 #define __cvt(a, b) _cvt (a, b)
 #define CVT(a) __cvt (a, CLIB_CUCKOO_TYPE)

 typedef u64 clib_cuckoo_bucket_aux_t;

 #define CLIB_CUCKOO_USE_COUNT_BIT_WIDTH (1 + CLIB_CUCKOO_LOG2_KVP_PER_BUCKET)

 always_inline u64
 clib_cuckoo_bucket_aux_get_version (clib_cuckoo_bucket_aux_t aux)
 {
   return aux >> (1 + CLIB_CUCKOO_USE_COUNT_BIT_WIDTH);
 }

 always_inline int
 clib_cuckoo_bucket_aux_get_use_count (clib_cuckoo_bucket_aux_t aux)
 {
   u64 use_count_mask = (1 << CLIB_CUCKOO_USE_COUNT_BIT_WIDTH) - 1;
   return (aux >> 1) & use_count_mask;
 }

 always_inline int
 clib_cuckoo_bucket_aux_get_writer_flag (clib_cuckoo_bucket_aux_t aux)
 {
   return aux & 1;
 }

 always_inline clib_cuckoo_bucket_aux_t
 clib_cuckoo_bucket_aux_pack (u64 version, int use_count, int writer_flag)
 {
   return (version << (1 + CLIB_CUCKOO_USE_COUNT_BIT_WIDTH)) +
     (use_count << 1) + writer_flag;
 }

 always_inline clib_cuckoo_bucket_aux_t
 clib_cuckoo_bucket_aux_set_version (clib_cuckoo_bucket_aux_t aux, u64 version)
 {
   int use_count = clib_cuckoo_bucket_aux_get_use_count (aux);
   int writer_flag = clib_cuckoo_bucket_aux_get_writer_flag (aux);
   return clib_cuckoo_bucket_aux_pack (version, use_count, writer_flag);
 }

 always_inline clib_cuckoo_bucket_aux_t
 clib_cuckoo_bucket_aux_set_use_count (clib_cuckoo_bucket_aux_t aux,
 				      int use_count)
 {
   u64 version = clib_cuckoo_bucket_aux_get_version (aux);
   int writer_flag = clib_cuckoo_bucket_aux_get_writer_flag (aux);
   return clib_cuckoo_bucket_aux_pack (version, use_count, writer_flag);
 }

 always_inline clib_cuckoo_bucket_aux_t
 clib_cuckoo_bucket_aux_set_writer_flag (clib_cuckoo_bucket_aux_t aux,
 					int writer_flag)
 {
   u64 version = clib_cuckoo_bucket_aux_get_version (aux);
   int use_count = clib_cuckoo_bucket_aux_get_use_count (aux);
   return clib_cuckoo_bucket_aux_pack (version, use_count, writer_flag);
 }

 #define PATH_BITS_REQ \
   (CLIB_CUCKOO_BFS_MAX_PATH_LENGTH * CLIB_CUCKOO_LOG2_KVP_PER_BUCKET)

 #if PATH_BITS_REQ <= 8
 typedef u8 path_data_t;
 #elif PATH_BITS_REQ <= 16
 typedef u16 path_data_t;
 #elif PATH_BITS_REQ <= 32
 typedef u32 path_data_t;
 #elif PATH_BITS_REQ <= 64
 typedef u64 path_data_t;
 #else
 #error no suitable datatype for path storage...
 #endif

 typedef struct
 {
   /** bucket where this path begins */
   u64 start;
   /** bucket at end of path */
   u64 bucket;
   /** length of the path */
   u8 length;
   /** holds compressed offsets in buckets along path */
   path_data_t data;
 } clib_cuckoo_path_t;

 typedef struct
 {
   CLIB_CACHE_LINE_ALIGN_MARK (cacheline0);

   /** reduced hashes corresponding to elements */
   u8 reduced_hashes[CLIB_CUCKOO_KVP_PER_BUCKET];

   /** auxiliary data - version, writer flag and used count */
   volatile clib_cuckoo_bucket_aux_t aux;

   /** cuckoo elements in this bucket */
     CVT (clib_cuckoo_kv) elts[CLIB_CUCKOO_KVP_PER_BUCKET];
 } CVT (clib_cuckoo_bucket);

 #define clib_cuckoo_bucket_foreach_idx(var) \
   for (var = 0; var < CLIB_CUCKOO_KVP_PER_BUCKET; var++)

 #if CLIB_CUCKOO_OPTIMIZE_UNROLL
 #if CLIB_CUCKOO_KVP_PER_BUCKET == 2
 #define clib_cuckoo_bucket_foreach_idx_unrolled(var, body) \
   do                                                       \
     {                                                      \
       var = 0;                                             \
       body;                                                \
       var = 1;                                             \
       body;                                                \
     }                                                      \
   while (0);
 #elif CLIB_CUCKOO_KVP_PER_BUCKET == 4
 #define clib_cuckoo_bucket_foreach_idx_unrolled(var, body) \
   do                                                       \
     {                                                      \
       var = 0;                                             \
       body;                                                \
       var = 1;                                             \
       body;                                                \
       var = 2;                                             \
       body;                                                \
       var = 3;                                             \
       body;                                                \
     }                                                      \
   while (0);
 #elif CLIB_CUCKOO_KVP_PER_BUCKET == 8
 #define clib_cuckoo_bucket_foreach_idx_unrolled(var, body) \
   do                                                       \
     {                                                      \
       var = 0;                                             \
       body;                                                \
       var = 1;                                             \
       body;                                                \
       var = 2;                                             \
       body;                                                \
       var = 3;                                             \
       body;                                                \
       var = 4;                                             \
       body;                                                \
       var = 5;                                             \
       body;                                                \
       var = 6;                                             \
       body;                                                \
       var = 7;                                             \
       body;                                                \
     }                                                      \
   while (0);
 #else
 #define clib_cuckoo_bucket_foreach_idx_unrolled(var, body) \
   clib_cuckoo_bucket_foreach_idx (var)                     \
   {                                                        \
     body;                                                  \
   }
 #endif
 #else /* CLIB_CUCKOO_OPTIMIZE_UNROLL */
 #define clib_cuckoo_bucket_foreach_idx_unrolled(var, body) \
   clib_cuckoo_bucket_foreach_idx (var)                     \
   {                                                        \
     body;                                                  \
   }
 #endif /* CLIB_CUCKOO_OPTIMIZE_UNROLL */

 #define clib_cuckoo_bucket_foreach_elt_index(var, bucket) \
   for (var = 0; var < CLIB_CUCKOO_KVP_PER_BUCKET; ++i)

 #define clib_cuckoo_foreach_bucket(var, h, body)        \
   do                                                    \
     {                                                   \
       CVT (clib_cuckoo_bucket) *__buckets = h->buckets; \
       vec_foreach (var, __buckets)                      \
       {                                                 \
         body;                                           \
       }                                                 \
     }                                                   \
   while (0)

 typedef struct CV (clib_cuckoo)
 {
   /** vector of elements containing key-value pairs and auxiliary data */
   CVT (clib_cuckoo_bucket) * volatile buckets;

   /** garbage to be freed once its safe to do so .. */
   CVT (clib_cuckoo_bucket) * *to_be_freed;

   /** hash table name */
   const char *name;

   /** pool of cuckoo paths (reused when doing bfd search) */
   clib_cuckoo_path_t *paths;

   /**
    * vector used as queue when doing cuckoo path searches - holds offsets
    * in paths pool
    */
   uword *bfs_search_queue;

   /**
    * writer lock - whether this lock is taken or not has zero effect on
    * readers
    */
   clib_spinlock_t writer_lock;

   /** caller context passed to callback with garbage notification */
   void *garbage_ctx;

   /**
    * garbage notify function - called when some garbage needs to be collected
    * in main thread while other threads are stopped
    */
   void (*garbage_callback) (struct CV (clib_cuckoo) * h, void *garbage_ctx);

 #if CLIB_CUCKOO_DEBUG_COUNTERS
   u64 steps_exceeded;
   u64 bfs_queue_emptied;
   u64 fast_adds;
   u64 slow_adds;
   u64 rehashes;
 #endif

 } CVT (clib_cuckoo);

 void CV (clib_cuckoo_init) (CVT (clib_cuckoo) * h, const char *name,
 			    uword nbuckets,
 			    void (*garbage_callback) (CVT (clib_cuckoo) *,
 						      void *),
 			    void *garbage_ctx);

 void CV (clib_cuckoo_garbage_collect) (CVT (clib_cuckoo) * h);

 void CV (clib_cuckoo_free) (CVT (clib_cuckoo) * h);

 int CV (clib_cuckoo_add_del) (CVT (clib_cuckoo) * h,
 			      CVT (clib_cuckoo_kv) * add_v, int is_add,
 			      int dont_overwrite);
 int CV (clib_cuckoo_search) (CVT (clib_cuckoo) * h,
 			     CVT (clib_cuckoo_kv) * search_v,
 			     CVT (clib_cuckoo_kv) * return_v);

 void CV (clib_cuckoo_foreach_key_value_pair) (CVT (clib_cuckoo) * h,
 					      void *callback, void *arg);

 float CV (clib_cuckoo_calc_load) (CVT (clib_cuckoo) * h);

 format_function_t CV (format_cuckoo);
 format_function_t CV (format_cuckoo_kvp);

 always_inline u8
 clib_cuckoo_reduce_hash (u64 hash)
 {
   u32 v32 = ((u32) hash) ^ ((u32) (hash >> 32));
   u16 v16 = ((u16) v32) ^ ((u16) (v32 >> 16));
   u8 v8 = ((u8) v16) ^ ((u8) (v16 >> 8));
   return v8;
 }

 always_inline u64
 clib_cuckoo_get_other_bucket (u64 nbuckets, u64 bucket, u8 reduced_hash)
 {
   u64 mask = (nbuckets - 1);
   return (bucket ^ ((reduced_hash + 1) * 0xc6a4a7935bd1e995)) & mask;
 }

 always_inline clib_cuckoo_lookup_info_t
 CV (clib_cuckoo_calc_lookup) (CVT (clib_cuckoo_bucket) * buckets, u64 hash)
 {
   clib_cuckoo_lookup_info_t lookup;
   u64 nbuckets = vec_len (buckets);
   u64 mask = (nbuckets - 1);
   lookup.bucket1 = hash & mask;
 #if CLIB_CUCKOO_OPTIMIZE_PREFETCH
   CLIB_PREFETCH (vec_elt_at_index (buckets, lookup.bucket1),
 		 sizeof (*buckets), LOAD);
 #endif
   u8 reduced_hash = clib_cuckoo_reduce_hash (hash);
   lookup.bucket2 =
     clib_cuckoo_get_other_bucket (nbuckets, lookup.bucket1, reduced_hash);
 #if CLIB_CUCKOO_OPTIMIZE_PREFETCH
   CLIB_PREFETCH (vec_elt_at_index (buckets, lookup.bucket2),
 		 sizeof (*buckets), LOAD);
 #endif
   lookup.reduced_hash = reduced_hash;
   ASSERT (lookup.bucket1 < nbuckets);
   ASSERT (lookup.bucket2 < nbuckets);
   return lookup;
 }

 /**
  * search for key within bucket
  */
 always_inline int CV (clib_cuckoo_bucket_search) (CVT (clib_cuckoo_bucket) *
 						  b,
 						  CVT (clib_cuckoo_kv) * kvp,
 						  u8 reduced_hash)
 {
   clib_cuckoo_bucket_aux_t bucket_aux;
   u8 writer_flag;
   do
     {
       bucket_aux = b->aux;
       writer_flag = clib_cuckoo_bucket_aux_get_writer_flag (bucket_aux);
     }
   while (PREDICT_FALSE (writer_flag));	/* loop while writer flag is set */

   int i;
 #if CLIB_CUCKOO_OPTIMIZE_USE_COUNT_LIMITS_SEARCH
   const int use_count = clib_cuckoo_bucket_aux_get_use_count (bucket_aux);
 #endif
   /* *INDENT-OFF* */
   clib_cuckoo_bucket_foreach_idx_unrolled (i, {
 #if CLIB_CUCKOO_OPTIMIZE_USE_COUNT_LIMITS_SEARCH
     if (i > use_count)
       {
         break;
       }
 #endif
     if (
 #if CLIB_CUCKOO_OPTIMIZE_CMP_REDUCED_HASH
         reduced_hash == b->reduced_hashes[i] &&
 #endif
         0 == memcmp (&kvp->key, &b->elts[i].key, sizeof (kvp->key)))
       {
         kvp->value = b->elts[i].value;
         clib_cuckoo_bucket_aux_t bucket_aux2 = b->aux;
         if (PREDICT_TRUE (clib_cuckoo_bucket_aux_get_version (bucket_aux) ==
                           clib_cuckoo_bucket_aux_get_version (bucket_aux2)))
           {
             /* yay, fresh data */
             return CLIB_CUCKOO_ERROR_SUCCESS;
           }
         else
           {
             /* oops, modification detected */
             return CLIB_CUCKOO_ERROR_AGAIN;
           }
       }
   });
   /* *INDENT-ON* */
   return CLIB_CUCKOO_ERROR_NOT_FOUND;
 }

 always_inline int CV (clib_cuckoo_search_inline) (CVT (clib_cuckoo) * h,
 						  CVT (clib_cuckoo_kv) * kvp)
 {
   clib_cuckoo_lookup_info_t lookup;
   int rv;

   u64 hash = CV (clib_cuckoo_hash) (kvp);
   CVT (clib_cuckoo_bucket) * buckets;
 again:
   buckets = h->buckets;
   lookup = CV (clib_cuckoo_calc_lookup) (buckets, hash);
   do
     {
       rv =
 	CV (clib_cuckoo_bucket_search) (vec_elt_at_index
 					(buckets, lookup.bucket1), kvp,
 					lookup.reduced_hash);
     }
   while (PREDICT_FALSE (CLIB_CUCKOO_ERROR_AGAIN == rv));
   if (CLIB_CUCKOO_ERROR_SUCCESS == rv)
     {
       return CLIB_CUCKOO_ERROR_SUCCESS;
     }

   rv =
     CV (clib_cuckoo_bucket_search) (vec_elt_at_index
 				    (buckets, lookup.bucket2), kvp,
 				    lookup.reduced_hash);
   if (PREDICT_FALSE (CLIB_CUCKOO_ERROR_AGAIN == rv))
     {
       /*
        * change to 2nd bucket could bump the item to 1st bucket and the bucket
        * indexes might not even be valid anymore - restart the search
        */
       goto again;
     }
   return rv;
 }

 #endif /* __included_cuckoo_template_h__ */

 /** @endcond */

 /*
  * fd.io coding-style-patch-verification: ON
  *
  * Local Variables:
  * eval: (c-set-style "gnu")
  * End:
  */
	/*
	Copyright (c) 2017 Cisco and/or its affiliates.

	* Licensed under the Apache License, Version 2.0 (the "License");
	* you may not use this file except in compliance with the License.
	* You may obtain a copy of the License at:
	*
	* http://www.apache.org/licenses/LICENSE-2.0
	*
	* Unless required by applicable law or agreed to in writing, software
	* distributed under the License is distributed on an "AS IS" BASIS,
	* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
	* See the License for the specific language governing permissions and
	* limitations under the License.
	*/

	/*
	* cuckoo hash implementation based on paper
	* 'Algorithmic Improvements for Fast Concurrent Cuckoo Hashing'
	* by Xiaozhou Li, David G. Andersen, Michael Kaminsky, Michael J. Freedman
	* and their libcuckoo implementation (https://github.com/efficient/libcuckoo)
	*/

	/*
	* Note: to instantiate the template multiple times in a single file,
	* #undef __included_cuckoo_template_h__...
	*/
	#ifndef __included_cuckoo_template_h__
	#define __included_cuckoo_template_h__

	#include <vppinfra/heap.h>
	#include <vppinfra/format.h>
	#include <vppinfra/pool.h>
	#include <vppinfra/lock.h>
	#include <vppinfra/error.h>
	#include <vppinfra/hash.h>
	#include <vppinfra/cache.h>

	#ifndef CLIB_CUCKOO_TYPE
	#error CLIB_CUCKOO_TYPE not defined
	#endif

	#ifndef CLIB_CUCKOO_BFS_MAX_STEPS
	#error CLIB_CUCKOO_BFS_MAX_STEPS not defined
	#endif

	#ifndef CLIB_CUCKOO_KVP_PER_BUCKET
	#error CLIB_CUCKOO_KVP_PER_BUCKET not defined
	#endif

	#ifndef CLIB_CUCKOO_LOG2_KVP_PER_BUCKET
	#error CLIB_CUCKOO_LOG2_KVP_PER_BUCKET not defined
	#endif

	#ifndef CLIB_CUCKOO_BFS_MAX_PATH_LENGTH
	#error CLIB_CUCKOO_BFS_MAX_PATH_LENGTH not defined
	#endif

	STATIC_ASSERT (CLIB_CUCKOO_KVP_PER_BUCKET ==
	(1 << CLIB_CUCKOO_LOG2_KVP_PER_BUCKET),
	"CLIB_CUCKOO_KVP_PER_BUCKET != (1 << CLIB_CUCKOO_LOG2_KVP_PER_BUCKET");

	#define _cv(a, b) a##b
	#define __cv(a, b) _cv (a, b)
	#define CV(a) __cv (a, CLIB_CUCKOO_TYPE)

	#define _cvt(a, b) a##b##_t
	#define __cvt(a, b) _cvt (a, b)
	#define CVT(a) __cvt (a, CLIB_CUCKOO_TYPE)

	typedef u64 clib_cuckoo_bucket_aux_t;

	#define CLIB_CUCKOO_USE_COUNT_BIT_WIDTH (1 + CLIB_CUCKOO_LOG2_KVP_PER_BUCKET)

	always_inline u64
	clib_cuckoo_bucket_aux_get_version (clib_cuckoo_bucket_aux_t aux)
	{
	return aux >> (1 + CLIB_CUCKOO_USE_COUNT_BIT_WIDTH);
	}

	always_inline int
	clib_cuckoo_bucket_aux_get_use_count (clib_cuckoo_bucket_aux_t aux)
	{
	u64 use_count_mask = (1 << CLIB_CUCKOO_USE_COUNT_BIT_WIDTH) - 1;
	return (aux >> 1) & use_count_mask;
	}

	always_inline int
	clib_cuckoo_bucket_aux_get_writer_flag (clib_cuckoo_bucket_aux_t aux)
	{
	return aux & 1;
	}

	always_inline clib_cuckoo_bucket_aux_t
	clib_cuckoo_bucket_aux_pack (u64 version, int use_count, int writer_flag)
	{
	return (version << (1 + CLIB_CUCKOO_USE_COUNT_BIT_WIDTH)) +
	(use_count << 1) + writer_flag;
	}

	always_inline clib_cuckoo_bucket_aux_t
	clib_cuckoo_bucket_aux_set_version (clib_cuckoo_bucket_aux_t aux, u64 version)
	{
	int use_count = clib_cuckoo_bucket_aux_get_use_count (aux);
	int writer_flag = clib_cuckoo_bucket_aux_get_writer_flag (aux);
	return clib_cuckoo_bucket_aux_pack (version, use_count, writer_flag);
	}

	always_inline clib_cuckoo_bucket_aux_t
	clib_cuckoo_bucket_aux_set_use_count (clib_cuckoo_bucket_aux_t aux,
	int use_count)
	{
	u64 version = clib_cuckoo_bucket_aux_get_version (aux);
	int writer_flag = clib_cuckoo_bucket_aux_get_writer_flag (aux);
	return clib_cuckoo_bucket_aux_pack (version, use_count, writer_flag);
	}

	always_inline clib_cuckoo_bucket_aux_t
	clib_cuckoo_bucket_aux_set_writer_flag (clib_cuckoo_bucket_aux_t aux,
	int writer_flag)
	{
	u64 version = clib_cuckoo_bucket_aux_get_version (aux);
	int use_count = clib_cuckoo_bucket_aux_get_use_count (aux);
	return clib_cuckoo_bucket_aux_pack (version, use_count, writer_flag);
	}

	#define PATH_BITS_REQ \
	(CLIB_CUCKOO_BFS_MAX_PATH_LENGTH * CLIB_CUCKOO_LOG2_KVP_PER_BUCKET)

	#if PATH_BITS_REQ <= 8
	typedef u8 path_data_t;
	#elif PATH_BITS_REQ <= 16
	typedef u16 path_data_t;
	#elif PATH_BITS_REQ <= 32
	typedef u32 path_data_t;
	#elif PATH_BITS_REQ <= 64
	typedef u64 path_data_t;
	#else
	#error no suitable datatype for path storage...
	#endif

	typedef struct
	{
	/** bucket where this path begins */
	u64 start;
	/** bucket at end of path */
	u64 bucket;
	/** length of the path */
	u8 length;
	/** holds compressed offsets in buckets along path */
	path_data_t data;
	} clib_cuckoo_path_t;

	typedef struct
	{
	CLIB_CACHE_LINE_ALIGN_MARK (cacheline0);

	/** reduced hashes corresponding to elements */
	u8 reduced_hashes[CLIB_CUCKOO_KVP_PER_BUCKET];

	/** auxiliary data - version, writer flag and used count */
	volatile clib_cuckoo_bucket_aux_t aux;

	/** cuckoo elements in this bucket */
	CVT (clib_cuckoo_kv) elts[CLIB_CUCKOO_KVP_PER_BUCKET];
	} CVT (clib_cuckoo_bucket);

	#define clib_cuckoo_bucket_foreach_idx(var) \
	for (var = 0; var < CLIB_CUCKOO_KVP_PER_BUCKET; var++)

	#if CLIB_CUCKOO_OPTIMIZE_UNROLL
	#if CLIB_CUCKOO_KVP_PER_BUCKET == 2
	#define clib_cuckoo_bucket_foreach_idx_unrolled(var, body) \
	do \
	{ \
	var = 0; \
	body; \
	var = 1; \
	body; \
	} \
	while (0);
	#elif CLIB_CUCKOO_KVP_PER_BUCKET == 4
	#define clib_cuckoo_bucket_foreach_idx_unrolled(var, body) \
	do \
	{ \
	var = 0; \
	body; \
	var = 1; \
	body; \
	var = 2; \
	body; \
	var = 3; \
	body; \
	} \
	while (0);
	#elif CLIB_CUCKOO_KVP_PER_BUCKET == 8
	#define clib_cuckoo_bucket_foreach_idx_unrolled(var, body) \
	do \
	{ \
	var = 0; \
	body; \
	var = 1; \
	body; \
	var = 2; \
	body; \
	var = 3; \
	body; \
	var = 4; \
	body; \
	var = 5; \
	body; \
	var = 6; \
	body; \
	var = 7; \
	body; \
	} \
	while (0);
	#else
	#define clib_cuckoo_bucket_foreach_idx_unrolled(var, body) \
	clib_cuckoo_bucket_foreach_idx (var) \
	{ \
	body; \
	}
	#endif
	#else /* CLIB_CUCKOO_OPTIMIZE_UNROLL */
	#define clib_cuckoo_bucket_foreach_idx_unrolled(var, body) \
	clib_cuckoo_bucket_foreach_idx (var) \
	{ \
	body; \
	}
	#endif /* CLIB_CUCKOO_OPTIMIZE_UNROLL */

	#define clib_cuckoo_bucket_foreach_elt_index(var, bucket) \
	for (var = 0; var < CLIB_CUCKOO_KVP_PER_BUCKET; ++i)

	#define clib_cuckoo_foreach_bucket(var, h, body) \
	do \
	{ \
	CVT (clib_cuckoo_bucket) *__buckets = h->buckets; \
	vec_foreach (var, __buckets) \
	{ \
	body; \
	} \
	} \
	while (0)

	typedef struct CV (clib_cuckoo)
	{
	/** vector of elements containing key-value pairs and auxiliary data */
	CVT (clib_cuckoo_bucket) * volatile buckets;

	/** garbage to be freed once its safe to do so .. */
	CVT (clib_cuckoo_bucket) * *to_be_freed;

	/** hash table name */
	const char *name;

	/** pool of cuckoo paths (reused when doing bfd search) */
	clib_cuckoo_path_t *paths;

	/**
	* vector used as queue when doing cuckoo path searches - holds offsets
	* in paths pool
	*/
	uword *bfs_search_queue;

	/**
	* writer lock - whether this lock is taken or not has zero effect on
	* readers
	*/
	clib_spinlock_t writer_lock;

	/** caller context passed to callback with garbage notification */
	void *garbage_ctx;

	/**
	* garbage notify function - called when some garbage needs to be collected
	* in main thread while other threads are stopped
	*/
	void (garbage_callback) (struct CV (clib_cuckoo) h, void *garbage_ctx);

	#if CLIB_CUCKOO_DEBUG_COUNTERS
	u64 steps_exceeded;
	u64 bfs_queue_emptied;
	u64 fast_adds;
	u64 slow_adds;
	u64 rehashes;
	#endif

	} CVT (clib_cuckoo);

	void CV (clib_cuckoo_init) (CVT (clib_cuckoo) * h, const char *name,
	uword nbuckets,
	void (garbage_callback) (CVT (clib_cuckoo) ,
	void *),
	void *garbage_ctx);

	void CV (clib_cuckoo_garbage_collect) (CVT (clib_cuckoo) * h);

	void CV (clib_cuckoo_free) (CVT (clib_cuckoo) * h);

	int CV (clib_cuckoo_add_del) (CVT (clib_cuckoo) * h,
	CVT (clib_cuckoo_kv) * add_v, int is_add,
	int dont_overwrite);
	int CV (clib_cuckoo_search) (CVT (clib_cuckoo) * h,
	CVT (clib_cuckoo_kv) * search_v,
	CVT (clib_cuckoo_kv) * return_v);

	void CV (clib_cuckoo_foreach_key_value_pair) (CVT (clib_cuckoo) * h,
	void callback, void arg);

	float CV (clib_cuckoo_calc_load) (CVT (clib_cuckoo) * h);

	format_function_t CV (format_cuckoo);
	format_function_t CV (format_cuckoo_kvp);

	always_inline u8
	clib_cuckoo_reduce_hash (u64 hash)
	{
	u32 v32 = ((u32) hash) ^ ((u32) (hash >> 32));
	u16 v16 = ((u16) v32) ^ ((u16) (v32 >> 16));
	u8 v8 = ((u8) v16) ^ ((u8) (v16 >> 8));
	return v8;
	}

	always_inline u64
	clib_cuckoo_get_other_bucket (u64 nbuckets, u64 bucket, u8 reduced_hash)
	{
	u64 mask = (nbuckets - 1);
	return (bucket ^ ((reduced_hash + 1) * 0xc6a4a7935bd1e995)) & mask;
	}

	always_inline clib_cuckoo_lookup_info_t
	CV (clib_cuckoo_calc_lookup) (CVT (clib_cuckoo_bucket) * buckets, u64 hash)
	{
	clib_cuckoo_lookup_info_t lookup;
	u64 nbuckets = vec_len (buckets);
	u64 mask = (nbuckets - 1);
	lookup.bucket1 = hash & mask;
	#if CLIB_CUCKOO_OPTIMIZE_PREFETCH
	CLIB_PREFETCH (vec_elt_at_index (buckets, lookup.bucket1),
	sizeof (*buckets), LOAD);
	#endif
	u8 reduced_hash = clib_cuckoo_reduce_hash (hash);
	lookup.bucket2 =
	clib_cuckoo_get_other_bucket (nbuckets, lookup.bucket1, reduced_hash);
	#if CLIB_CUCKOO_OPTIMIZE_PREFETCH
	CLIB_PREFETCH (vec_elt_at_index (buckets, lookup.bucket2),
	sizeof (*buckets), LOAD);
	#endif
	lookup.reduced_hash = reduced_hash;
	ASSERT (lookup.bucket1 < nbuckets);
	ASSERT (lookup.bucket2 < nbuckets);
	return lookup;
	}

	/**
	* search for key within bucket
	*/
	always_inline int CV (clib_cuckoo_bucket_search) (CVT (clib_cuckoo_bucket) *
	b,
	CVT (clib_cuckoo_kv) * kvp,
	u8 reduced_hash)
	{
	clib_cuckoo_bucket_aux_t bucket_aux;
	u8 writer_flag;
	do
	{
	bucket_aux = b->aux;
	writer_flag = clib_cuckoo_bucket_aux_get_writer_flag (bucket_aux);
	}
	while (PREDICT_FALSE (writer_flag)); /* loop while writer flag is set */

	int i;
	#if CLIB_CUCKOO_OPTIMIZE_USE_COUNT_LIMITS_SEARCH
	const int use_count = clib_cuckoo_bucket_aux_get_use_count (bucket_aux);
	#endif
	/* INDENT-OFF */
	clib_cuckoo_bucket_foreach_idx_unrolled (i, {
	#if CLIB_CUCKOO_OPTIMIZE_USE_COUNT_LIMITS_SEARCH
	if (i > use_count)
	{
	break;
	}
	#endif
	if (
	#if CLIB_CUCKOO_OPTIMIZE_CMP_REDUCED_HASH
	reduced_hash == b->reduced_hashes[i] &&
	#endif
	0 == memcmp (&kvp->key, &b->elts[i].key, sizeof (kvp->key)))
	{
	kvp->value = b->elts[i].value;
	clib_cuckoo_bucket_aux_t bucket_aux2 = b->aux;
	if (PREDICT_TRUE (clib_cuckoo_bucket_aux_get_version (bucket_aux) ==
	clib_cuckoo_bucket_aux_get_version (bucket_aux2)))
	{
	/* yay, fresh data */
	return CLIB_CUCKOO_ERROR_SUCCESS;
	}
	else
	{
	/* oops, modification detected */
	return CLIB_CUCKOO_ERROR_AGAIN;
	}
	}
	});
	/* INDENT-ON */
	return CLIB_CUCKOO_ERROR_NOT_FOUND;
	}

	always_inline int CV (clib_cuckoo_search_inline) (CVT (clib_cuckoo) * h,
	CVT (clib_cuckoo_kv) * kvp)
	{
	clib_cuckoo_lookup_info_t lookup;
	int rv;

	u64 hash = CV (clib_cuckoo_hash) (kvp);
	CVT (clib_cuckoo_bucket) * buckets;
	again:
	buckets = h->buckets;
	lookup = CV (clib_cuckoo_calc_lookup) (buckets, hash);
	do
	{
	rv =
	CV (clib_cuckoo_bucket_search) (vec_elt_at_index
	(buckets, lookup.bucket1), kvp,
	lookup.reduced_hash);
	}
	while (PREDICT_FALSE (CLIB_CUCKOO_ERROR_AGAIN == rv));
	if (CLIB_CUCKOO_ERROR_SUCCESS == rv)
	{
	return CLIB_CUCKOO_ERROR_SUCCESS;
	}

	rv =
	CV (clib_cuckoo_bucket_search) (vec_elt_at_index
	(buckets, lookup.bucket2), kvp,
	lookup.reduced_hash);
	if (PREDICT_FALSE (CLIB_CUCKOO_ERROR_AGAIN == rv))
	{
	/*
	* change to 2nd bucket could bump the item to 1st bucket and the bucket
	* indexes might not even be valid anymore - restart the search
	*/
	goto again;
	}
	return rv;
	}

	#endif /* __included_cuckoo_template_h__ */

	/** @endcond */

	/*
	* fd.io coding-style-patch-verification: ON
	*
	* Local Variables:
	* eval: (c-set-style "gnu")
	* End:
	*/