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

 /*
   Copyright (c) 2014 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.
 */

 /** @cond DOCUMENTATION_IS_IN_BIHASH_DOC_H */

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

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

 #ifndef BIHASH_TYPE
 #error BIHASH_TYPE not defined
 #endif

 #ifdef BIHASH_32_64_SVM
 #include <vppinfra/linux/syscall.h>
 #include <fcntl.h>
 #define F_LINUX_SPECIFIC_BASE 1024
 #define F_ADD_SEALS (F_LINUX_SPECIFIC_BASE + 9)
 #define F_SEAL_SHRINK (2)
 /* Max page size 2**16 due to refcount width  */
 #define BIHASH_FREELIST_LENGTH 17
 #endif

 /* default is 2MB, use 30 for 1GB */
 #ifndef BIHASH_LOG2_HUGEPAGE_SIZE
 #define BIHASH_LOG2_HUGEPAGE_SIZE 21
 #endif

 #define _bv(a,b) a##b
 #define __bv(a,b) _bv(a,b)
 #define BV(a) __bv(a,BIHASH_TYPE)

 #define _bvt(a,b) a##b##_t
 #define __bvt(a,b) _bvt(a,b)
 #define BVT(a) __bvt(a,BIHASH_TYPE)

 #define _bvs(a,b) struct a##b
 #define __bvs(a,b) _bvs(a,b)
 #define BVS(a) __bvs(a,BIHASH_TYPE)

 #if _LP64 == 0
 #define OVERFLOW_ASSERT(x) ASSERT(((x) & 0xFFFFFFFF00000000ULL) == 0)
 #define u64_to_pointer(x) (void *)(u32)((x))
 #define pointer_to_u64(x) (u64)(u32)((x))
 #else
 #define OVERFLOW_ASSERT(x)
 #define u64_to_pointer(x) (void *)((x))
 #define pointer_to_u64(x) (u64)((x))
 #endif

 typedef struct BV (clib_bihash_value)
 {
   union
   {
     BVT (clib_bihash_kv) kvp[BIHASH_KVP_PER_PAGE];
     u64 next_free_as_u64;
   };
 } BVT (clib_bihash_value);

 #define BIHASH_BUCKET_OFFSET_BITS 36

 typedef struct
 {
   union
   {
     struct
     {
       u64 offset:BIHASH_BUCKET_OFFSET_BITS;
       u64 lock:1;
       u64 linear_search:1;
       u64 log2_pages:8;
       u64 refcnt:16;
     };
     u64 as_u64;
   };
 } BVT (clib_bihash_bucket);

 STATIC_ASSERT_SIZEOF (BVT (clib_bihash_bucket), sizeof (u64));

 /* *INDENT-OFF* */
 typedef CLIB_PACKED (struct {
   /*
    * Backing store allocation. Since bihash manages its own
    * freelists, we simple dole out memory starting from alloc_arena[alloc_arena_next].
    */
   u64 alloc_arena_next;	/* Next offset from alloc_arena to allocate, definitely NOT a constant */
   u64 alloc_arena_size;	/* Size of the arena */
   u64 alloc_arena_mapped;	/* Size of the mapped memory in the arena */
   /* Two SVM pointers stored as 8-byte integers */
   u64 alloc_lock_as_u64;
   u64 buckets_as_u64;
   /* freelist list-head arrays/vectors */
   u64 freelists_as_u64;
   u32 nbuckets;	/* Number of buckets */
   /* Set when header valid */
   volatile u32 ready;
   u64 pad[1];
 }) BVT (clib_bihash_shared_header);
 /* *INDENT-ON* */

 STATIC_ASSERT_SIZEOF (BVT (clib_bihash_shared_header), 8 * sizeof (u64));

 typedef
 BVS (clib_bihash_alloc_chunk)
 {
   CLIB_CACHE_LINE_ALIGN_MARK (cacheline0);

   /* chunk size */
   uword size;

   /* pointer to the next allocation */
   u8 *next_alloc;

   /* number of bytes left in this chunk */
   uword bytes_left;

   /* doubly linked list of heap allocated chunks */
   BVS (clib_bihash_alloc_chunk) * prev, *next;

 } BVT (clib_bihash_alloc_chunk);

 typedef
 BVS (clib_bihash)
 {
   BVT (clib_bihash_bucket) * buckets;
   volatile u32 *alloc_lock;

   BVT (clib_bihash_value) ** working_copies;
   int *working_copy_lengths;
   BVT (clib_bihash_bucket) saved_bucket;

   u32 nbuckets;
   u32 log2_nbuckets;
   u64 memory_size;
   u8 *name;
   format_function_t *fmt_fn;
   void *heap;
   BVT (clib_bihash_alloc_chunk) * chunks;

   u64 *freelists;

 #if BIHASH_32_64_SVM
   BVT (clib_bihash_shared_header) * sh;
   int memfd;
 #else
   BVT (clib_bihash_shared_header) sh;
 #endif

   u64 alloc_arena;		/* Base of the allocation arena */
   volatile u8 instantiated;
   u8 dont_add_to_all_bihash_list;

   /**
     * A custom format function to print the Key and Value of bihash_key instead of default hexdump
     */
   format_function_t *kvp_fmt_fn;

   /** Optional statistics-gathering callback */
 #if BIHASH_ENABLE_STATS
   void (*inc_stats_callback) (BVS (clib_bihash) *, int stat_id, u64 count);

   /** Statistics callback context (e.g. address of stats data structure) */
   void *inc_stats_context;
 #endif

 } BVT (clib_bihash);

 typedef struct
 {
   BVT (clib_bihash) * h;
   char *name;
   u32 nbuckets;
   uword memory_size;
   format_function_t *kvp_fmt_fn;
   u8 instantiate_immediately;
   u8 dont_add_to_all_bihash_list;
 } BVT (clib_bihash_init2_args);

 extern void **clib_all_bihashes;

 #if BIHASH_32_64_SVM
 #undef alloc_arena_next
 #undef alloc_arena_size
 #undef alloc_arena_mapped
 #undef alloc_arena
 #undef CLIB_BIHASH_READY_MAGIC
 #define alloc_arena_next(h) (((h)->sh)->alloc_arena_next)
 #define alloc_arena_size(h) (((h)->sh)->alloc_arena_size)
 #define alloc_arena_mapped(h) (((h)->sh)->alloc_arena_mapped)
 #define alloc_arena(h) ((h)->alloc_arena)
 #define CLIB_BIHASH_READY_MAGIC 0xFEEDFACE
 #else
 #undef alloc_arena_next
 #undef alloc_arena_size
 #undef alloc_arena_mapped
 #undef alloc_arena
 #undef CLIB_BIHASH_READY_MAGIC
 #define alloc_arena_next(h) ((h)->sh.alloc_arena_next)
 #define alloc_arena_size(h) ((h)->sh.alloc_arena_size)
 #define alloc_arena_mapped(h) ((h)->sh.alloc_arena_mapped)
 #define alloc_arena(h) ((h)->alloc_arena)
 #define CLIB_BIHASH_READY_MAGIC 0
 #endif

 #ifndef BIHASH_STAT_IDS
 #define BIHASH_STAT_IDS 1

 #define foreach_bihash_stat                     \
 _(alloc_add)                                    \
 _(add)                                          \
 _(split_add)                                    \
 _(replace)                                      \
 _(update)                                       \
 _(del)                                          \
 _(del_free)                                     \
 _(linear)                                       \
 _(resplit)                                      \
 _(working_copy_lost)                            \
 _(splits)			/* must be last */

 typedef enum
 {
 #define _(a) BIHASH_STAT_##a,
   foreach_bihash_stat
 #undef _
     BIHASH_STAT_N_STATS,
 } BVT (clib_bihash_stat_id);
 #endif /* BIHASH_STAT_IDS */

 static inline void BV (clib_bihash_increment_stat) (BVT (clib_bihash) * h,
 						    int stat_id, u64 count)
 {
 #if BIHASH_ENABLE_STATS
   if (PREDICT_FALSE (h->inc_stats_callback != 0))
     h->inc_stats_callback (h, stat_id, count);
 #endif
 }

 #if BIHASH_ENABLE_STATS
 static inline void BV (clib_bihash_set_stats_callback)
   (BVT (clib_bihash) * h, void (*cb) (BVT (clib_bihash) *, int, u64),
    void *ctx)
 {
   h->inc_stats_callback = cb;
   h->inc_stats_context = ctx;
 }
 #endif


 static inline void BV (clib_bihash_alloc_lock) (BVT (clib_bihash) * h)
 {
   while (__atomic_test_and_set (h->alloc_lock, __ATOMIC_ACQUIRE))
     CLIB_PAUSE ();
 }

 static inline void BV (clib_bihash_alloc_unlock) (BVT (clib_bihash) * h)
 {
   __atomic_clear (h->alloc_lock, __ATOMIC_RELEASE);
 }

 static inline void BV (clib_bihash_lock_bucket) (BVT (clib_bihash_bucket) * b)
 {
   /* *INDENT-OFF* */
   BVT (clib_bihash_bucket) mask = { .lock = 1 };
   /* *INDENT-ON* */
   u64 old;

 try_again:
   old = clib_atomic_fetch_or (&b->as_u64, mask.as_u64);

   if (PREDICT_FALSE (old & mask.as_u64))
     {
       /* somebody else flipped the bit, try again */
       CLIB_PAUSE ();
       goto try_again;
     }
 }

 static inline void BV (clib_bihash_unlock_bucket)
   (BVT (clib_bihash_bucket) * b)
 {
   b->lock = 0;
 }

 static inline void *BV (clib_bihash_get_value) (BVT (clib_bihash) * h,
 						uword offset)
 {
   u8 *hp = (u8 *) (uword) alloc_arena (h);
   u8 *vp = hp + offset;

   return (void *) vp;
 }

 static inline int BV (clib_bihash_bucket_is_empty)
   (BVT (clib_bihash_bucket) * b)
 {
   /* Note: applied to locked buckets, test offset */
   if (BIHASH_KVP_AT_BUCKET_LEVEL == 0)
     return b->offset == 0;
   else
     return (b->log2_pages == 0 && b->refcnt == 1);
 }

 static inline uword BV (clib_bihash_get_offset) (BVT (clib_bihash) * h,
 						 void *v)
 {
   u8 *hp, *vp;

   hp = (u8 *) (uword) alloc_arena (h);
   vp = (u8 *) v;

   return vp - hp;
 }

 #define BIHASH_ADD 1
 #define BIHASH_DEL 0

 void BV (clib_bihash_init)
   (BVT (clib_bihash) * h, char *name, u32 nbuckets, uword memory_size);

 void BV (clib_bihash_init2) (BVT (clib_bihash_init2_args) * a);

 #if BIHASH_32_64_SVM
 void BV (clib_bihash_initiator_init_svm)
   (BVT (clib_bihash) * h, char *name, u32 nbuckets, u64 memory_size);
 void BV (clib_bihash_responder_init_svm)
   (BVT (clib_bihash) * h, char *name, int fd);
 #endif

 void BV (clib_bihash_set_kvp_format_fn) (BVT (clib_bihash) * h,
 					 format_function_t * kvp_fmt_fn);

 void BV (clib_bihash_free) (BVT (clib_bihash) * h);

 int BV (clib_bihash_add_del) (BVT (clib_bihash) * h,
 			      BVT (clib_bihash_kv) * add_v, int is_add);

 int BV (clib_bihash_add_del_with_hash) (BVT (clib_bihash) * h,
 					BVT (clib_bihash_kv) * add_v, u64 hash,
 					int is_add);
 int BV (clib_bihash_add_or_overwrite_stale) (BVT (clib_bihash) * h,
 					     BVT (clib_bihash_kv) * add_v,
 					     int (*is_stale_cb) (BVT
 								 (clib_bihash_kv)
 								 *, void *),
 					     void *arg);
 int BV (clib_bihash_add_with_overwrite_cb) (
   BVT (clib_bihash) * h, BVT (clib_bihash_kv) * add_v,
   void (*overwrite_cb) (BVT (clib_bihash_kv) *, void *), void *arg);
 int BV (clib_bihash_search) (BVT (clib_bihash) * h,
 			     BVT (clib_bihash_kv) * search_v,
 			     BVT (clib_bihash_kv) * return_v);

 int BV (clib_bihash_is_initialised) (const BVT (clib_bihash) * h);

 #define BIHASH_WALK_STOP 0
 #define BIHASH_WALK_CONTINUE 1

 typedef
   int (*BV (clib_bihash_foreach_key_value_pair_cb)) (BVT (clib_bihash_kv) *,
 						     void *);
 void BV (clib_bihash_foreach_key_value_pair) (BVT (clib_bihash) * h,
 					      BV
 					      (clib_bihash_foreach_key_value_pair_cb)
 					      cb, void *arg);
 void *clib_all_bihash_set_heap (void);
 void clib_bihash_copied (void *dst, void *src);

 format_function_t BV (format_bihash);
 format_function_t BV (format_bihash_kvp);
 format_function_t BV (format_bihash_lru);

 static inline
 BVT (clib_bihash_bucket) *
 BV (clib_bihash_get_bucket) (BVT (clib_bihash) * h, u64 hash)
 {
 #if BIHASH_KVP_AT_BUCKET_LEVEL
   uword offset;
   offset = (hash & (h->nbuckets - 1));
   offset = offset * (sizeof (BVT (clib_bihash_bucket))
 		     + (BIHASH_KVP_PER_PAGE * sizeof (BVT (clib_bihash_kv))));
   return ((BVT (clib_bihash_bucket) *) (((u8 *) h->buckets) + offset));
 #else
   return h->buckets + (hash & (h->nbuckets - 1));
 #endif
 }

 static inline int BV (clib_bihash_search_inline_with_hash)
   (BVT (clib_bihash) * h, u64 hash, BVT (clib_bihash_kv) * key_result)
 {
   BVT (clib_bihash_value) * v;
   BVT (clib_bihash_bucket) * b;
   int i, limit;

   /* *INDENT-OFF* */
   static const BVT (clib_bihash_bucket) mask = {
     .linear_search = 1,
     .log2_pages = -1
   };
   /* *INDENT-ON* */

 #if BIHASH_LAZY_INSTANTIATE
   if (PREDICT_FALSE (h->instantiated == 0))
     return -1;
 #endif

   b = BV (clib_bihash_get_bucket) (h, hash);

   if (PREDICT_FALSE (BV (clib_bihash_bucket_is_empty) (b)))
     return -1;

   if (PREDICT_FALSE (b->lock))
     {
       volatile BVT (clib_bihash_bucket) * bv = b;
       while (bv->lock)
 	CLIB_PAUSE ();
     }

   v = BV (clib_bihash_get_value) (h, b->offset);

   /* If the bucket has unresolvable collisions, use linear search */
   limit = BIHASH_KVP_PER_PAGE;

   if (PREDICT_FALSE (b->as_u64 & mask.as_u64))
     {
       if (PREDICT_FALSE (b->linear_search))
 	limit <<= b->log2_pages;
       else
 	v += extract_bits (hash, h->log2_nbuckets, b->log2_pages);
     }

   for (i = 0; i < limit; i++)
     {
       if (BV (clib_bihash_key_compare) (v->kvp[i].key, key_result->key))
 	{
 	  *key_result = v->kvp[i];
 	  return 0;
 	}
     }
   return -1;
 }

 static inline int BV (clib_bihash_search_inline)
   (BVT (clib_bihash) * h, BVT (clib_bihash_kv) * key_result)
 {
   u64 hash;

   hash = BV (clib_bihash_hash) (key_result);

   return BV (clib_bihash_search_inline_with_hash) (h, hash, key_result);
 }

 static inline void BV (clib_bihash_prefetch_bucket)
   (BVT (clib_bihash) * h, u64 hash)
 {
   CLIB_PREFETCH (BV (clib_bihash_get_bucket) (h, hash),
 		 BIHASH_BUCKET_PREFETCH_CACHE_LINES * CLIB_CACHE_LINE_BYTES,
 		 LOAD);
 }

 static inline void BV (clib_bihash_prefetch_data)
   (BVT (clib_bihash) * h, u64 hash)
 {
   BVT (clib_bihash_value) * v;
   BVT (clib_bihash_bucket) * b;

 #if BIHASH_LAZY_INSTANTIATE
   if (PREDICT_FALSE (h->instantiated == 0))
     return;
 #endif

   b = BV (clib_bihash_get_bucket) (h, hash);

   if (PREDICT_FALSE (BV (clib_bihash_bucket_is_empty) (b)))
     return;

   v = BV (clib_bihash_get_value) (h, b->offset);

   if (PREDICT_FALSE (b->log2_pages && b->linear_search == 0))
     v += extract_bits (hash, h->log2_nbuckets, b->log2_pages);

   CLIB_PREFETCH (v, BIHASH_KVP_PER_PAGE * sizeof (BVT (clib_bihash_kv)),
 		 LOAD);
 }

 static inline int BV (clib_bihash_search_inline_2_with_hash)
   (BVT (clib_bihash) * h,
    u64 hash, BVT (clib_bihash_kv) * search_key, BVT (clib_bihash_kv) * valuep)
 {
   BVT (clib_bihash_value) * v;
   BVT (clib_bihash_bucket) * b;
   int i, limit;

 /* *INDENT-OFF* */
   static const BVT (clib_bihash_bucket) mask = {
     .linear_search = 1,
     .log2_pages = -1
   };
 /* *INDENT-ON* */

   ASSERT (valuep);

 #if BIHASH_LAZY_INSTANTIATE
   if (PREDICT_FALSE (h->instantiated == 0))
     return -1;
 #endif

   b = BV (clib_bihash_get_bucket) (h, hash);

   if (PREDICT_FALSE (BV (clib_bihash_bucket_is_empty) (b)))
     return -1;

   if (PREDICT_FALSE (b->lock))
     {
       volatile BVT (clib_bihash_bucket) * bv = b;
       while (bv->lock)
 	CLIB_PAUSE ();
     }

   v = BV (clib_bihash_get_value) (h, b->offset);

   /* If the bucket has unresolvable collisions, use linear search */
   limit = BIHASH_KVP_PER_PAGE;

   if (PREDICT_FALSE (b->as_u64 & mask.as_u64))
     {
       if (PREDICT_FALSE (b->linear_search))
 	limit <<= b->log2_pages;
       else
 	v += extract_bits (hash, h->log2_nbuckets, b->log2_pages);
     }

   for (i = 0; i < limit; i++)
     {
       if (BV (clib_bihash_key_compare) (v->kvp[i].key, search_key->key))
 	{
 	  *valuep = v->kvp[i];
 	  return 0;
 	}
     }
   return -1;
 }

 static inline int BV (clib_bihash_search_inline_2)
   (BVT (clib_bihash) * h,
    BVT (clib_bihash_kv) * search_key, BVT (clib_bihash_kv) * valuep)
 {
   u64 hash;

   hash = BV (clib_bihash_hash) (search_key);

   return BV (clib_bihash_search_inline_2_with_hash) (h, hash, search_key,
 						     valuep);
 }


 #endif /* __included_bihash_template_h__ */

 /** @endcond */

 /*
  * fd.io coding-style-patch-verification: ON
  *
  * Local Variables:
  * eval: (c-set-style "gnu")
  * End:
  */
	/*
	Copyright (c) 2014 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.
	*/

	/** @cond DOCUMENTATION_IS_IN_BIHASH_DOC_H */

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

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

	#ifndef BIHASH_TYPE
	#error BIHASH_TYPE not defined
	#endif

	#ifdef BIHASH_32_64_SVM
	#include <vppinfra/linux/syscall.h>
	#include <fcntl.h>
	#define F_LINUX_SPECIFIC_BASE 1024
	#define F_ADD_SEALS (F_LINUX_SPECIFIC_BASE + 9)
	#define F_SEAL_SHRINK (2)
	/* Max page size 2*16 due to refcount width /
	#define BIHASH_FREELIST_LENGTH 17
	#endif

	/* default is 2MB, use 30 for 1GB */
	#ifndef BIHASH_LOG2_HUGEPAGE_SIZE
	#define BIHASH_LOG2_HUGEPAGE_SIZE 21
	#endif

	#define _bv(a,b) a##b
	#define __bv(a,b) _bv(a,b)
	#define BV(a) __bv(a,BIHASH_TYPE)

	#define _bvt(a,b) a##b##_t
	#define __bvt(a,b) _bvt(a,b)
	#define BVT(a) __bvt(a,BIHASH_TYPE)

	#define _bvs(a,b) struct a##b
	#define __bvs(a,b) _bvs(a,b)
	#define BVS(a) __bvs(a,BIHASH_TYPE)

	#if _LP64 == 0
	#define OVERFLOW_ASSERT(x) ASSERT(((x) & 0xFFFFFFFF00000000ULL) == 0)
	#define u64_to_pointer(x) (void *)(u32)((x))
	#define pointer_to_u64(x) (u64)(u32)((x))
	#else
	#define OVERFLOW_ASSERT(x)
	#define u64_to_pointer(x) (void *)((x))
	#define pointer_to_u64(x) (u64)((x))
	#endif

	typedef struct BV (clib_bihash_value)
	{
	union
	{
	BVT (clib_bihash_kv) kvp[BIHASH_KVP_PER_PAGE];
	u64 next_free_as_u64;
	};
	} BVT (clib_bihash_value);

	#define BIHASH_BUCKET_OFFSET_BITS 36

	typedef struct
	{
	union
	{
	struct
	{
	u64 offset:BIHASH_BUCKET_OFFSET_BITS;
	u64 lock:1;
	u64 linear_search:1;
	u64 log2_pages:8;
	u64 refcnt:16;
	};
	u64 as_u64;
	};
	} BVT (clib_bihash_bucket);

	STATIC_ASSERT_SIZEOF (BVT (clib_bihash_bucket), sizeof (u64));

	/* INDENT-OFF */
	typedef CLIB_PACKED (struct {
	/*
	* Backing store allocation. Since bihash manages its own
	* freelists, we simple dole out memory starting from alloc_arena[alloc_arena_next].
	*/
	u64 alloc_arena_next; /* Next offset from alloc_arena to allocate, definitely NOT a constant */
	u64 alloc_arena_size; /* Size of the arena */
	u64 alloc_arena_mapped; /* Size of the mapped memory in the arena */
	/* Two SVM pointers stored as 8-byte integers */
	u64 alloc_lock_as_u64;
	u64 buckets_as_u64;
	/* freelist list-head arrays/vectors */
	u64 freelists_as_u64;
	u32 nbuckets; /* Number of buckets */
	/* Set when header valid */
	volatile u32 ready;
	u64 pad[1];
	}) BVT (clib_bihash_shared_header);
	/* INDENT-ON */

	STATIC_ASSERT_SIZEOF (BVT (clib_bihash_shared_header), 8 * sizeof (u64));

	typedef
	BVS (clib_bihash_alloc_chunk)
	{
	CLIB_CACHE_LINE_ALIGN_MARK (cacheline0);

	/* chunk size */
	uword size;

	/* pointer to the next allocation */
	u8 *next_alloc;

	/* number of bytes left in this chunk */
	uword bytes_left;

	/* doubly linked list of heap allocated chunks */
	BVS (clib_bihash_alloc_chunk) * prev, *next;

	} BVT (clib_bihash_alloc_chunk);

	typedef
	BVS (clib_bihash)
	{
	BVT (clib_bihash_bucket) * buckets;
	volatile u32 *alloc_lock;

	BVT (clib_bihash_value) ** working_copies;
	int *working_copy_lengths;
	BVT (clib_bihash_bucket) saved_bucket;

	u32 nbuckets;
	u32 log2_nbuckets;
	u64 memory_size;
	u8 *name;
	format_function_t *fmt_fn;
	void *heap;
	BVT (clib_bihash_alloc_chunk) * chunks;

	u64 *freelists;

	#if BIHASH_32_64_SVM
	BVT (clib_bihash_shared_header) * sh;
	int memfd;
	#else
	BVT (clib_bihash_shared_header) sh;
	#endif

	u64 alloc_arena; /* Base of the allocation arena */
	volatile u8 instantiated;
	u8 dont_add_to_all_bihash_list;

	/**
	* A custom format function to print the Key and Value of bihash_key instead of default hexdump
	*/
	format_function_t *kvp_fmt_fn;

	/** Optional statistics-gathering callback */
	#if BIHASH_ENABLE_STATS
	void (inc_stats_callback) (BVS (clib_bihash) , int stat_id, u64 count);

	/** Statistics callback context (e.g. address of stats data structure) */
	void *inc_stats_context;
	#endif

	} BVT (clib_bihash);

	typedef struct
	{
	BVT (clib_bihash) * h;
	char *name;
	u32 nbuckets;
	uword memory_size;
	format_function_t *kvp_fmt_fn;
	u8 instantiate_immediately;
	u8 dont_add_to_all_bihash_list;
	} BVT (clib_bihash_init2_args);

	extern void **clib_all_bihashes;

	#if BIHASH_32_64_SVM
	#undef alloc_arena_next
	#undef alloc_arena_size
	#undef alloc_arena_mapped
	#undef alloc_arena
	#undef CLIB_BIHASH_READY_MAGIC
	#define alloc_arena_next(h) (((h)->sh)->alloc_arena_next)
	#define alloc_arena_size(h) (((h)->sh)->alloc_arena_size)
	#define alloc_arena_mapped(h) (((h)->sh)->alloc_arena_mapped)
	#define alloc_arena(h) ((h)->alloc_arena)
	#define CLIB_BIHASH_READY_MAGIC 0xFEEDFACE
	#else
	#undef alloc_arena_next
	#undef alloc_arena_size
	#undef alloc_arena_mapped
	#undef alloc_arena
	#undef CLIB_BIHASH_READY_MAGIC
	#define alloc_arena_next(h) ((h)->sh.alloc_arena_next)
	#define alloc_arena_size(h) ((h)->sh.alloc_arena_size)
	#define alloc_arena_mapped(h) ((h)->sh.alloc_arena_mapped)
	#define alloc_arena(h) ((h)->alloc_arena)
	#define CLIB_BIHASH_READY_MAGIC 0
	#endif

	#ifndef BIHASH_STAT_IDS
	#define BIHASH_STAT_IDS 1

	#define foreach_bihash_stat \
	_(alloc_add) \
	_(add) \
	_(split_add) \
	_(replace) \
	_(update) \
	_(del) \
	_(del_free) \
	_(linear) \
	_(resplit) \
	_(working_copy_lost) \
	_(splits) /* must be last */

	typedef enum
	{
	#define _(a) BIHASH_STAT_##a,
	foreach_bihash_stat
	#undef _
	BIHASH_STAT_N_STATS,
	} BVT (clib_bihash_stat_id);
	#endif /* BIHASH_STAT_IDS */

	static inline void BV (clib_bihash_increment_stat) (BVT (clib_bihash) * h,
	int stat_id, u64 count)
	{
	#if BIHASH_ENABLE_STATS
	if (PREDICT_FALSE (h->inc_stats_callback != 0))
	h->inc_stats_callback (h, stat_id, count);
	#endif
	}

	#if BIHASH_ENABLE_STATS
	static inline void BV (clib_bihash_set_stats_callback)
	(BVT (clib_bihash) * h, void (cb) (BVT (clib_bihash) , int, u64),
	void *ctx)
	{
	h->inc_stats_callback = cb;
	h->inc_stats_context = ctx;
	}
	#endif


	static inline void BV (clib_bihash_alloc_lock) (BVT (clib_bihash) * h)
	{
	while (__atomic_test_and_set (h->alloc_lock, __ATOMIC_ACQUIRE))
	CLIB_PAUSE ();
	}

	static inline void BV (clib_bihash_alloc_unlock) (BVT (clib_bihash) * h)
	{
	__atomic_clear (h->alloc_lock, __ATOMIC_RELEASE);
	}

	static inline void BV (clib_bihash_lock_bucket) (BVT (clib_bihash_bucket) * b)
	{
	/* INDENT-OFF */
	BVT (clib_bihash_bucket) mask = { .lock = 1 };
	/* INDENT-ON */
	u64 old;

	try_again:
	old = clib_atomic_fetch_or (&b->as_u64, mask.as_u64);

	if (PREDICT_FALSE (old & mask.as_u64))
	{
	/* somebody else flipped the bit, try again */
	CLIB_PAUSE ();
	goto try_again;
	}
	}

	static inline void BV (clib_bihash_unlock_bucket)
	(BVT (clib_bihash_bucket) * b)
	{
	b->lock = 0;
	}

	static inline void BV (clib_bihash_get_value) (BVT (clib_bihash) h,
	uword offset)
	{
	u8 hp = (u8 ) (uword) alloc_arena (h);
	u8 *vp = hp + offset;

	return (void *) vp;
	}

	static inline int BV (clib_bihash_bucket_is_empty)
	(BVT (clib_bihash_bucket) * b)
	{
	/* Note: applied to locked buckets, test offset */
	if (BIHASH_KVP_AT_BUCKET_LEVEL == 0)
	return b->offset == 0;
	else
	return (b->log2_pages == 0 && b->refcnt == 1);
	}

	static inline uword BV (clib_bihash_get_offset) (BVT (clib_bihash) * h,
	void *v)
	{
	u8 hp, vp;

	hp = (u8 *) (uword) alloc_arena (h);
	vp = (u8 *) v;

	return vp - hp;
	}

	#define BIHASH_ADD 1
	#define BIHASH_DEL 0

	void BV (clib_bihash_init)
	(BVT (clib_bihash) * h, char *name, u32 nbuckets, uword memory_size);

	void BV (clib_bihash_init2) (BVT (clib_bihash_init2_args) * a);

	#if BIHASH_32_64_SVM
	void BV (clib_bihash_initiator_init_svm)
	(BVT (clib_bihash) * h, char *name, u32 nbuckets, u64 memory_size);
	void BV (clib_bihash_responder_init_svm)
	(BVT (clib_bihash) * h, char *name, int fd);
	#endif

	void BV (clib_bihash_set_kvp_format_fn) (BVT (clib_bihash) * h,
	format_function_t * kvp_fmt_fn);

	void BV (clib_bihash_free) (BVT (clib_bihash) * h);

	int BV (clib_bihash_add_del) (BVT (clib_bihash) * h,
	BVT (clib_bihash_kv) * add_v, int is_add);

	int BV (clib_bihash_add_del_with_hash) (BVT (clib_bihash) * h,
	BVT (clib_bihash_kv) * add_v, u64 hash,
	int is_add);
	int BV (clib_bihash_add_or_overwrite_stale) (BVT (clib_bihash) * h,
	BVT (clib_bihash_kv) * add_v,
	int (*is_stale_cb) (BVT
	(clib_bihash_kv)
	, void ),
	void *arg);
	int BV (clib_bihash_add_with_overwrite_cb) (
	BVT (clib_bihash) * h, BVT (clib_bihash_kv) * add_v,
	void (overwrite_cb) (BVT (clib_bihash_kv) , void ), void arg);
	int BV (clib_bihash_search) (BVT (clib_bihash) * h,
	BVT (clib_bihash_kv) * search_v,
	BVT (clib_bihash_kv) * return_v);

	int BV (clib_bihash_is_initialised) (const BVT (clib_bihash) * h);

	#define BIHASH_WALK_STOP 0
	#define BIHASH_WALK_CONTINUE 1

	typedef
	int (BV (clib_bihash_foreach_key_value_pair_cb)) (BVT (clib_bihash_kv) ,
	void *);
	void BV (clib_bihash_foreach_key_value_pair) (BVT (clib_bihash) * h,
	BV
	(clib_bihash_foreach_key_value_pair_cb)
	cb, void *arg);
	void *clib_all_bihash_set_heap (void);
	void clib_bihash_copied (void dst, void src);

	format_function_t BV (format_bihash);
	format_function_t BV (format_bihash_kvp);
	format_function_t BV (format_bihash_lru);

	static inline
	BVT (clib_bihash_bucket) *
	BV (clib_bihash_get_bucket) (BVT (clib_bihash) * h, u64 hash)
	{
	#if BIHASH_KVP_AT_BUCKET_LEVEL
	uword offset;
	offset = (hash & (h->nbuckets - 1));
	offset = offset * (sizeof (BVT (clib_bihash_bucket))
	+ (BIHASH_KVP_PER_PAGE * sizeof (BVT (clib_bihash_kv))));
	return ((BVT (clib_bihash_bucket) ) (((u8 ) h->buckets) + offset));
	#else
	return h->buckets + (hash & (h->nbuckets - 1));
	#endif
	}

	static inline int BV (clib_bihash_search_inline_with_hash)
	(BVT (clib_bihash) * h, u64 hash, BVT (clib_bihash_kv) * key_result)
	{
	BVT (clib_bihash_value) * v;
	BVT (clib_bihash_bucket) * b;
	int i, limit;

	/* INDENT-OFF */
	static const BVT (clib_bihash_bucket) mask = {
	.linear_search = 1,
	.log2_pages = -1
	};
	/* INDENT-ON */

	#if BIHASH_LAZY_INSTANTIATE
	if (PREDICT_FALSE (h->instantiated == 0))
	return -1;
	#endif

	b = BV (clib_bihash_get_bucket) (h, hash);

	if (PREDICT_FALSE (BV (clib_bihash_bucket_is_empty) (b)))
	return -1;

	if (PREDICT_FALSE (b->lock))
	{
	volatile BVT (clib_bihash_bucket) * bv = b;
	while (bv->lock)
	CLIB_PAUSE ();
	}

	v = BV (clib_bihash_get_value) (h, b->offset);

	/* If the bucket has unresolvable collisions, use linear search */
	limit = BIHASH_KVP_PER_PAGE;

	if (PREDICT_FALSE (b->as_u64 & mask.as_u64))
	{
	if (PREDICT_FALSE (b->linear_search))
	limit <<= b->log2_pages;
	else
	v += extract_bits (hash, h->log2_nbuckets, b->log2_pages);
	}

	for (i = 0; i < limit; i++)
	{
	if (BV (clib_bihash_key_compare) (v->kvp[i].key, key_result->key))
	{
	*key_result = v->kvp[i];
	return 0;
	}
	}
	return -1;
	}

	static inline int BV (clib_bihash_search_inline)
	(BVT (clib_bihash) * h, BVT (clib_bihash_kv) * key_result)
	{
	u64 hash;

	hash = BV (clib_bihash_hash) (key_result);

	return BV (clib_bihash_search_inline_with_hash) (h, hash, key_result);
	}

	static inline void BV (clib_bihash_prefetch_bucket)
	(BVT (clib_bihash) * h, u64 hash)
	{
	CLIB_PREFETCH (BV (clib_bihash_get_bucket) (h, hash),
	BIHASH_BUCKET_PREFETCH_CACHE_LINES * CLIB_CACHE_LINE_BYTES,
	LOAD);
	}

	static inline void BV (clib_bihash_prefetch_data)
	(BVT (clib_bihash) * h, u64 hash)
	{
	BVT (clib_bihash_value) * v;
	BVT (clib_bihash_bucket) * b;

	#if BIHASH_LAZY_INSTANTIATE
	if (PREDICT_FALSE (h->instantiated == 0))
	return;
	#endif

	b = BV (clib_bihash_get_bucket) (h, hash);

	if (PREDICT_FALSE (BV (clib_bihash_bucket_is_empty) (b)))
	return;

	v = BV (clib_bihash_get_value) (h, b->offset);

	if (PREDICT_FALSE (b->log2_pages && b->linear_search == 0))
	v += extract_bits (hash, h->log2_nbuckets, b->log2_pages);

	CLIB_PREFETCH (v, BIHASH_KVP_PER_PAGE * sizeof (BVT (clib_bihash_kv)),
	LOAD);
	}

	static inline int BV (clib_bihash_search_inline_2_with_hash)
	(BVT (clib_bihash) * h,
	u64 hash, BVT (clib_bihash_kv) * search_key, BVT (clib_bihash_kv) * valuep)
	{
	BVT (clib_bihash_value) * v;
	BVT (clib_bihash_bucket) * b;
	int i, limit;

	/* INDENT-OFF */
	static const BVT (clib_bihash_bucket) mask = {
	.linear_search = 1,
	.log2_pages = -1
	};
	/* INDENT-ON */

	ASSERT (valuep);

	#if BIHASH_LAZY_INSTANTIATE
	if (PREDICT_FALSE (h->instantiated == 0))
	return -1;
	#endif

	b = BV (clib_bihash_get_bucket) (h, hash);

	if (PREDICT_FALSE (BV (clib_bihash_bucket_is_empty) (b)))
	return -1;

	if (PREDICT_FALSE (b->lock))
	{
	volatile BVT (clib_bihash_bucket) * bv = b;
	while (bv->lock)
	CLIB_PAUSE ();
	}

	v = BV (clib_bihash_get_value) (h, b->offset);

	/* If the bucket has unresolvable collisions, use linear search */
	limit = BIHASH_KVP_PER_PAGE;

	if (PREDICT_FALSE (b->as_u64 & mask.as_u64))
	{
	if (PREDICT_FALSE (b->linear_search))
	limit <<= b->log2_pages;
	else
	v += extract_bits (hash, h->log2_nbuckets, b->log2_pages);
	}

	for (i = 0; i < limit; i++)
	{
	if (BV (clib_bihash_key_compare) (v->kvp[i].key, search_key->key))
	{
	*valuep = v->kvp[i];
	return 0;
	}
	}
	return -1;
	}

	static inline int BV (clib_bihash_search_inline_2)
	(BVT (clib_bihash) * h,
	BVT (clib_bihash_kv) * search_key, BVT (clib_bihash_kv) * valuep)
	{
	u64 hash;

	hash = BV (clib_bihash_hash) (search_key);

	return BV (clib_bihash_search_inline_2_with_hash) (h, hash, search_key,
	valuep);
	}


	#endif /* __included_bihash_template_h__ */

	/** @endcond */

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