vppinfra/vppinfra/bihash_template.c - fdio/vpp - Gitiles

 /*
  * Copyright (c) 2015 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.
  */

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

   nbuckets = 1 << (max_log2 (nbuckets));

   h->name = (u8 *)name;
   h->nbuckets = nbuckets;
   h->log2_nbuckets = max_log2 (nbuckets);

   h->mheap = mheap_alloc (0 /* use VM */, memory_size);

   oldheap = clib_mem_set_heap (h->mheap);
   vec_validate_aligned (h->buckets, nbuckets - 1, CLIB_CACHE_LINE_BYTES);
   h->writer_lock = clib_mem_alloc_aligned (CLIB_CACHE_LINE_BYTES,
                                            CLIB_CACHE_LINE_BYTES);

   clib_mem_set_heap (oldheap);
 }

 void BV(clib_bihash_free) (BVT(clib_bihash) * h)
 {
     mheap_free (h->mheap);
     memset (h, 0, sizeof (*h));
 }

 static BVT(clib_bihash_value) *
 BV(value_alloc) (BVT(clib_bihash) * h, u32 log2_pages)
 {
     BVT(clib_bihash_value) * rv = 0;
     void * oldheap;

     ASSERT (h->writer_lock[0]);
     if (log2_pages >= vec_len (h->freelists)
         || h->freelists [log2_pages] == 0)
     {
         oldheap = clib_mem_set_heap (h->mheap);

         vec_validate (h->freelists, log2_pages);
         vec_validate_aligned (rv, (1<<log2_pages) - 1, CLIB_CACHE_LINE_BYTES);
         clib_mem_set_heap (oldheap);
         goto initialize;
     }
     rv = h->freelists[log2_pages];
     h->freelists[log2_pages] = rv->next_free;

  initialize:
     ASSERT(rv);
     ASSERT (vec_len(rv) == (1<<log2_pages));
     /*
      * Latest gcc complains that the length arg is zero
      * if we replace (1<<log2_pages) with vec_len(rv).
      * No clue.
      */
     memset (rv, 0xff, sizeof (*rv) * (1<<log2_pages));
     return rv;
 }

 static void
 BV(value_free)
     (BVT(clib_bihash) * h,
      BVT(clib_bihash_value) * v)
 {
     u32 log2_pages;

     ASSERT (h->writer_lock[0]);

     log2_pages = min_log2(vec_len(v));

     ASSERT(vec_len (h->freelists) > log2_pages);

     v->next_free = h->freelists[log2_pages];
     h->freelists[log2_pages] = v;
 }

 static inline void
 BV(make_working_copy)
     (BVT(clib_bihash) * h, clib_bihash_bucket_t * b)
 {
   BVT(clib_bihash_value) * v;
   clib_bihash_bucket_t working_bucket __attribute__((aligned (8)));
   void * oldheap;
   BVT(clib_bihash_value) * working_copy;
   u32 cpu_number = os_get_cpu_number();

   if (cpu_number >= vec_len (h->working_copies))
     {
       oldheap = clib_mem_set_heap (h->mheap);
       vec_validate (h->working_copies, cpu_number);
       clib_mem_set_heap (oldheap);
     }

   /*
    * working_copies are per-cpu so that near-simultaneous
    * updates from multiple threads will not result in sporadic, spurious
    * lookup failures.
    */
   working_copy = h->working_copies[cpu_number];

   h->saved_bucket.as_u64 = b->as_u64;
   oldheap = clib_mem_set_heap (h->mheap);

   if ((1<<b->log2_pages) > vec_len (working_copy))
     {
       vec_validate_aligned (working_copy, (1<<b->log2_pages)-1,
                             sizeof (u64));
       h->working_copies[cpu_number] = working_copy;
     }

   _vec_len(working_copy) = 1<<b->log2_pages;
   clib_mem_set_heap (oldheap);

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

   memcpy (working_copy, v, sizeof (*v)*(1<<b->log2_pages));
   working_bucket.as_u64 = b->as_u64;
   working_bucket.offset = BV(clib_bihash_get_offset) (h, working_copy);
   CLIB_MEMORY_BARRIER();
   b->as_u64 = working_bucket.as_u64;
   h->working_copies[cpu_number] = working_copy;
 }

 static BVT(clib_bihash_value) *
     BV(split_and_rehash)
     (BVT(clib_bihash) * h,
      BVT(clib_bihash_value) * old_values,
      u32 new_log2_pages)
 {
   BVT(clib_bihash_value) * new_values, * v, * new_v;
   int i, j, k;

   new_values = BV(value_alloc) (h, new_log2_pages);

   v = old_values;
   for (i = 0; i < vec_len (old_values); i++)
     {
       u64 new_hash;

       for (j = 0; j < BIHASH_KVP_PER_PAGE; j++)
         {
           if (BV(clib_bihash_is_free)(&(v->kvp[j])) == 0)
             {
               new_hash = BV(clib_bihash_hash) (&(v->kvp[j]));
               new_hash >>= h->log2_nbuckets;
               new_hash &= (1<<new_log2_pages) - 1;

               new_v = &new_values [new_hash];

               for (k = 0; k < BIHASH_KVP_PER_PAGE; k++)
                 {
                   if (BV(clib_bihash_is_free)(&(new_v->kvp[k])))
                     {
                       memcpy (&(new_v->kvp[k]), &(v->kvp[j]),
                               sizeof (new_v->kvp[k]));
                       goto doublebreak;
                     }
                 }
               /* Crap. Tell caller to try again */
               BV(value_free) (h, new_values);
               return 0;
             }
         doublebreak:
           ;
         }
       v++;
     }
   return new_values;
 }

 int BV(clib_bihash_add_del)
      (BVT(clib_bihash) * h,
       BVT(clib_bihash_kv) * add_v,
       int is_add)
 {
   u32 bucket_index;
   clib_bihash_bucket_t * b, tmp_b;
   BVT(clib_bihash_value) * v, * new_v, * save_new_v, * working_copy;
   u32 value_index;
   int rv = 0;
   int i;
   u64 hash, new_hash;
   u32 new_log2_pages;
   u32 cpu_number = os_get_cpu_number();

   hash = BV(clib_bihash_hash) (add_v);

   bucket_index = hash & (h->nbuckets-1);
   b = &h->buckets[bucket_index];

   hash >>= h->log2_nbuckets;

   while (__sync_lock_test_and_set (h->writer_lock, 1))
     ;

   /* First elt in the bucket? */
   if (b->offset == 0)
     {
       if (is_add == 0)
         {
           rv = -1;
           goto unlock;
         }

       v = BV(value_alloc) (h, 0);
       *v->kvp = * add_v;
       tmp_b.as_u64 = 0;
       tmp_b.offset = BV(clib_bihash_get_offset) (h, v);

       b->as_u64 = tmp_b.as_u64;
       goto unlock;
     }

   BV(make_working_copy) (h, b);

   v = BV(clib_bihash_get_value) (h, h->saved_bucket.offset);
   value_index = hash & ((1<<h->saved_bucket.log2_pages)-1);
   v += value_index;

   if (is_add)
     {
       /*
        * For obvious (in hindsight) reasons, see if we're supposed to
        * replace an existing key, then look for an empty slot.
        */
       for (i = 0; i < BIHASH_KVP_PER_PAGE; i++)
         {
           if (!memcmp(&(v->kvp[i]), &add_v->key, sizeof (add_v->key)))
             {
               memcpy (&(v->kvp[i]), add_v, sizeof (*add_v));
               CLIB_MEMORY_BARRIER();
               /* Restore the previous (k,v) pairs */
               b->as_u64 = h->saved_bucket.as_u64;
               goto unlock;
             }
         }
       for (i = 0; i < BIHASH_KVP_PER_PAGE; i++)
         {
           if (BV(clib_bihash_is_free)(&(v->kvp[i])))
             {
               memcpy (&(v->kvp[i]), add_v, sizeof (*add_v));
               CLIB_MEMORY_BARRIER();
               b->as_u64 = h->saved_bucket.as_u64;
               goto unlock;
             }
         }
       /* no room at the inn... split case... */
     }
   else
     {
       for (i = 0; i < BIHASH_KVP_PER_PAGE; i++)
         {
           if (!memcmp(&(v->kvp[i]), &add_v->key, sizeof (add_v->key)))
             {
               memset (&(v->kvp[i]), 0xff, sizeof (*(add_v)));
               CLIB_MEMORY_BARRIER();
               b->as_u64 = h->saved_bucket.as_u64;
               goto unlock;
             }
         }
       rv = -3;
       b->as_u64 = h->saved_bucket.as_u64;
       goto unlock;
     }

   new_log2_pages = h->saved_bucket.log2_pages + 1;

  expand_again:
   working_copy = h->working_copies[cpu_number];
   new_v = BV(split_and_rehash) (h, working_copy, new_log2_pages);
   if (new_v == 0)
     {
       new_log2_pages++;
       goto expand_again;
     }

   /* Try to add the new entry */
   save_new_v = new_v;
   new_hash = BV(clib_bihash_hash) (add_v);
   new_hash >>= h->log2_nbuckets;
   new_hash &= (1<<min_log2(vec_len(new_v))) - 1;
   new_v += new_hash;

   for (i = 0; i < BIHASH_KVP_PER_PAGE; i++)
     {
       if (BV(clib_bihash_is_free)(&(new_v->kvp[i])))
         {
           memcpy (&(new_v->kvp[i]), add_v, sizeof (*add_v));
           goto expand_ok;
         }
     }
   /* Crap. Try again */
   new_log2_pages++;
   BV(value_free) (h, save_new_v);
   goto expand_again;

  expand_ok:
   tmp_b.log2_pages = min_log2 (vec_len (save_new_v));
   tmp_b.offset = BV(clib_bihash_get_offset) (h, save_new_v);
   CLIB_MEMORY_BARRIER();
   b->as_u64 = tmp_b.as_u64;
   v = BV(clib_bihash_get_value) (h, h->saved_bucket.offset);
   BV(value_free) (h, v);

  unlock:
   CLIB_MEMORY_BARRIER();
   h->writer_lock[0] = 0;
   return rv;
 }

 int BV(clib_bihash_search)
      (BVT(clib_bihash) * h,
       BVT(clib_bihash_kv) *search_key,
       BVT(clib_bihash_kv) *valuep)
 {
   u64 hash;
   u32 bucket_index;
   uword value_index;
   BVT(clib_bihash_value) * v;
   clib_bihash_bucket_t * b;
   int i;

   ASSERT(valuep);

   hash = BV(clib_bihash_hash) (search_key);

   bucket_index = hash & (h->nbuckets-1);
   b = &h->buckets[bucket_index];

   if (b->offset == 0)
     return -1;

   hash >>= h->log2_nbuckets;

   v = BV(clib_bihash_get_value) (h, b->offset);
   value_index = hash & ((1<<b->log2_pages)-1);
   v += value_index;

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

 u8 * BV(format_bihash) (u8 * s, va_list * args)
 {
   BVT(clib_bihash) * h
     = va_arg (*args, BVT(clib_bihash) *);
   int verbose = va_arg (*args, int);
   clib_bihash_bucket_t * b;
   BVT(clib_bihash_value) * v;
   int i, j, k;
   u64 active_elements = 0;

   s = format (s, "Hash table %s\n", h->name ? h->name : (u8 *) "(unnamed)");

   for (i = 0; i < h->nbuckets; i++)
     {
       b = &h->buckets [i];
       if (b->offset == 0)
         {
           if (verbose > 1)
             s = format (s, "[%d]: empty\n", i);
           continue;
         }

       if (verbose)
         {
           s = format (s, "[%d]: heap offset %d, len %d\n", i,
                       b->offset, (1<<b->log2_pages));
         }

       v = BV(clib_bihash_get_value) (h, b->offset);
       for (j = 0; j < (1<<b->log2_pages); j++)
         {
           for (k = 0; k < BIHASH_KVP_PER_PAGE; k++)
             {
               if (BV(clib_bihash_is_free)(&v->kvp[k]))
                 {
                   if (verbose > 1)
                     s = format (s, "    %d: empty\n",
                                 j * BIHASH_KVP_PER_PAGE + k);
                   continue;
                 }
               if (verbose)
                 {
                    s = format (s, "    %d: %U\n",
                               j * BIHASH_KVP_PER_PAGE + k,
                               BV(format_bihash_kvp),
                                &(v->kvp[k]));
                 }
               active_elements++;
             }
           v++;
         }
     }

   s = format (s, "    %lld active elements\n", active_elements);
   s = format (s, "    %d free lists\n", vec_len (h->freelists));
   s = format (s, "    %U\n", format_mheap, h->mheap, 1 /* verbose */);

   return s;
 }

 void BV(clib_bihash_foreach_key_value_pair)
     (BVT(clib_bihash) * h,
      void *callback,
      void *arg)
 {
   int i, j, k;
   clib_bihash_bucket_t * b;
   BVT(clib_bihash_value) * v;
   void (*fp)(BVT(clib_bihash_kv) *, void *) = callback;

   for (i = 0; i < h->nbuckets; i++)
     {
       b = &h->buckets [i];
       if (b->offset == 0)
         continue;

       v = BV(clib_bihash_get_value) (h, b->offset);
       for (j = 0; j < (1<<b->log2_pages); j++)
         {
           for (k = 0; k < BIHASH_KVP_PER_PAGE; k++)
             {
               if (BV(clib_bihash_is_free)(&v->kvp[k]))
                 continue;

               (*fp)(&v->kvp[k], arg);
             }
           v++;
         }
     }
 }
	/*
	* Copyright (c) 2015 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.
	*/

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

	nbuckets = 1 << (max_log2 (nbuckets));

	h->name = (u8 *)name;
	h->nbuckets = nbuckets;
	h->log2_nbuckets = max_log2 (nbuckets);

	h->mheap = mheap_alloc (0 /* use VM */, memory_size);

	oldheap = clib_mem_set_heap (h->mheap);
	vec_validate_aligned (h->buckets, nbuckets - 1, CLIB_CACHE_LINE_BYTES);
	h->writer_lock = clib_mem_alloc_aligned (CLIB_CACHE_LINE_BYTES,
	CLIB_CACHE_LINE_BYTES);

	clib_mem_set_heap (oldheap);
	}

	void BV(clib_bihash_free) (BVT(clib_bihash) * h)
	{
	mheap_free (h->mheap);
	memset (h, 0, sizeof (*h));
	}

	static BVT(clib_bihash_value) *
	BV(value_alloc) (BVT(clib_bihash) * h, u32 log2_pages)
	{
	BVT(clib_bihash_value) * rv = 0;
	void * oldheap;

	ASSERT (h->writer_lock[0]);
	if (log2_pages >= vec_len (h->freelists)
	\|\| h->freelists [log2_pages] == 0)
	{
	oldheap = clib_mem_set_heap (h->mheap);

	vec_validate (h->freelists, log2_pages);
	vec_validate_aligned (rv, (1<<log2_pages) - 1, CLIB_CACHE_LINE_BYTES);
	clib_mem_set_heap (oldheap);
	goto initialize;
	}
	rv = h->freelists[log2_pages];
	h->freelists[log2_pages] = rv->next_free;

	initialize:
	ASSERT(rv);
	ASSERT (vec_len(rv) == (1<<log2_pages));
	/*
	* Latest gcc complains that the length arg is zero
	* if we replace (1<<log2_pages) with vec_len(rv).
	* No clue.
	*/
	memset (rv, 0xff, sizeof (rv) (1<<log2_pages));
	return rv;
	}

	static void
	BV(value_free)
	(BVT(clib_bihash) * h,
	BVT(clib_bihash_value) * v)
	{
	u32 log2_pages;

	ASSERT (h->writer_lock[0]);

	log2_pages = min_log2(vec_len(v));

	ASSERT(vec_len (h->freelists) > log2_pages);

	v->next_free = h->freelists[log2_pages];
	h->freelists[log2_pages] = v;
	}

	static inline void
	BV(make_working_copy)
	(BVT(clib_bihash) * h, clib_bihash_bucket_t * b)
	{
	BVT(clib_bihash_value) * v;
	clib_bihash_bucket_t working_bucket __attribute__((aligned (8)));
	void * oldheap;
	BVT(clib_bihash_value) * working_copy;
	u32 cpu_number = os_get_cpu_number();

	if (cpu_number >= vec_len (h->working_copies))
	{
	oldheap = clib_mem_set_heap (h->mheap);
	vec_validate (h->working_copies, cpu_number);
	clib_mem_set_heap (oldheap);
	}

	/*
	* working_copies are per-cpu so that near-simultaneous
	* updates from multiple threads will not result in sporadic, spurious
	* lookup failures.
	*/
	working_copy = h->working_copies[cpu_number];

	h->saved_bucket.as_u64 = b->as_u64;
	oldheap = clib_mem_set_heap (h->mheap);

	if ((1<<b->log2_pages) > vec_len (working_copy))
	{
	vec_validate_aligned (working_copy, (1<<b->log2_pages)-1,
	sizeof (u64));
	h->working_copies[cpu_number] = working_copy;
	}

	_vec_len(working_copy) = 1<<b->log2_pages;
	clib_mem_set_heap (oldheap);

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

	memcpy (working_copy, v, sizeof (v)(1<<b->log2_pages));
	working_bucket.as_u64 = b->as_u64;
	working_bucket.offset = BV(clib_bihash_get_offset) (h, working_copy);
	CLIB_MEMORY_BARRIER();
	b->as_u64 = working_bucket.as_u64;
	h->working_copies[cpu_number] = working_copy;
	}

	static BVT(clib_bihash_value) *
	BV(split_and_rehash)
	(BVT(clib_bihash) * h,
	BVT(clib_bihash_value) * old_values,
	u32 new_log2_pages)
	{
	BVT(clib_bihash_value) * new_values, * v, * new_v;
	int i, j, k;

	new_values = BV(value_alloc) (h, new_log2_pages);

	v = old_values;
	for (i = 0; i < vec_len (old_values); i++)
	{
	u64 new_hash;

	for (j = 0; j < BIHASH_KVP_PER_PAGE; j++)
	{
	if (BV(clib_bihash_is_free)(&(v->kvp[j])) == 0)
	{
	new_hash = BV(clib_bihash_hash) (&(v->kvp[j]));
	new_hash >>= h->log2_nbuckets;
	new_hash &= (1<<new_log2_pages) - 1;

	new_v = &new_values [new_hash];

	for (k = 0; k < BIHASH_KVP_PER_PAGE; k++)
	{
	if (BV(clib_bihash_is_free)(&(new_v->kvp[k])))
	{
	memcpy (&(new_v->kvp[k]), &(v->kvp[j]),
	sizeof (new_v->kvp[k]));
	goto doublebreak;
	}
	}
	/* Crap. Tell caller to try again */
	BV(value_free) (h, new_values);
	return 0;
	}
	doublebreak:
	;
	}
	v++;
	}
	return new_values;
	}

	int BV(clib_bihash_add_del)
	(BVT(clib_bihash) * h,
	BVT(clib_bihash_kv) * add_v,
	int is_add)
	{
	u32 bucket_index;
	clib_bihash_bucket_t * b, tmp_b;
	BVT(clib_bihash_value) * v, * new_v, * save_new_v, * working_copy;
	u32 value_index;
	int rv = 0;
	int i;
	u64 hash, new_hash;
	u32 new_log2_pages;
	u32 cpu_number = os_get_cpu_number();

	hash = BV(clib_bihash_hash) (add_v);

	bucket_index = hash & (h->nbuckets-1);
	b = &h->buckets[bucket_index];

	hash >>= h->log2_nbuckets;

	while (__sync_lock_test_and_set (h->writer_lock, 1))
	;

	/* First elt in the bucket? */
	if (b->offset == 0)
	{
	if (is_add == 0)
	{
	rv = -1;
	goto unlock;
	}

	v = BV(value_alloc) (h, 0);
	v->kvp = add_v;
	tmp_b.as_u64 = 0;
	tmp_b.offset = BV(clib_bihash_get_offset) (h, v);

	b->as_u64 = tmp_b.as_u64;
	goto unlock;
	}

	BV(make_working_copy) (h, b);

	v = BV(clib_bihash_get_value) (h, h->saved_bucket.offset);
	value_index = hash & ((1<<h->saved_bucket.log2_pages)-1);
	v += value_index;

	if (is_add)
	{
	/*
	* For obvious (in hindsight) reasons, see if we're supposed to
	* replace an existing key, then look for an empty slot.
	*/
	for (i = 0; i < BIHASH_KVP_PER_PAGE; i++)
	{
	if (!memcmp(&(v->kvp[i]), &add_v->key, sizeof (add_v->key)))
	{
	memcpy (&(v->kvp[i]), add_v, sizeof (*add_v));
	CLIB_MEMORY_BARRIER();
	/* Restore the previous (k,v) pairs */
	b->as_u64 = h->saved_bucket.as_u64;
	goto unlock;
	}
	}
	for (i = 0; i < BIHASH_KVP_PER_PAGE; i++)
	{
	if (BV(clib_bihash_is_free)(&(v->kvp[i])))
	{
	memcpy (&(v->kvp[i]), add_v, sizeof (*add_v));
	CLIB_MEMORY_BARRIER();
	b->as_u64 = h->saved_bucket.as_u64;
	goto unlock;
	}
	}
	/* no room at the inn... split case... */
	}
	else
	{
	for (i = 0; i < BIHASH_KVP_PER_PAGE; i++)
	{
	if (!memcmp(&(v->kvp[i]), &add_v->key, sizeof (add_v->key)))
	{
	memset (&(v->kvp[i]), 0xff, sizeof (*(add_v)));
	CLIB_MEMORY_BARRIER();
	b->as_u64 = h->saved_bucket.as_u64;
	goto unlock;
	}
	}
	rv = -3;
	b->as_u64 = h->saved_bucket.as_u64;
	goto unlock;
	}

	new_log2_pages = h->saved_bucket.log2_pages + 1;

	expand_again:
	working_copy = h->working_copies[cpu_number];
	new_v = BV(split_and_rehash) (h, working_copy, new_log2_pages);
	if (new_v == 0)
	{
	new_log2_pages++;
	goto expand_again;
	}

	/* Try to add the new entry */
	save_new_v = new_v;
	new_hash = BV(clib_bihash_hash) (add_v);
	new_hash >>= h->log2_nbuckets;
	new_hash &= (1<<min_log2(vec_len(new_v))) - 1;
	new_v += new_hash;

	for (i = 0; i < BIHASH_KVP_PER_PAGE; i++)
	{
	if (BV(clib_bihash_is_free)(&(new_v->kvp[i])))
	{
	memcpy (&(new_v->kvp[i]), add_v, sizeof (*add_v));
	goto expand_ok;
	}
	}
	/* Crap. Try again */
	new_log2_pages++;
	BV(value_free) (h, save_new_v);
	goto expand_again;

	expand_ok:
	tmp_b.log2_pages = min_log2 (vec_len (save_new_v));
	tmp_b.offset = BV(clib_bihash_get_offset) (h, save_new_v);
	CLIB_MEMORY_BARRIER();
	b->as_u64 = tmp_b.as_u64;
	v = BV(clib_bihash_get_value) (h, h->saved_bucket.offset);
	BV(value_free) (h, v);

	unlock:
	CLIB_MEMORY_BARRIER();
	h->writer_lock[0] = 0;
	return rv;
	}

	int BV(clib_bihash_search)
	(BVT(clib_bihash) * h,
	BVT(clib_bihash_kv) *search_key,
	BVT(clib_bihash_kv) *valuep)
	{
	u64 hash;
	u32 bucket_index;
	uword value_index;
	BVT(clib_bihash_value) * v;
	clib_bihash_bucket_t * b;
	int i;

	ASSERT(valuep);

	hash = BV(clib_bihash_hash) (search_key);

	bucket_index = hash & (h->nbuckets-1);
	b = &h->buckets[bucket_index];

	if (b->offset == 0)
	return -1;

	hash >>= h->log2_nbuckets;

	v = BV(clib_bihash_get_value) (h, b->offset);
	value_index = hash & ((1<<b->log2_pages)-1);
	v += value_index;

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

	u8 * BV(format_bihash) (u8 * s, va_list * args)
	{
	BVT(clib_bihash) * h
	= va_arg (args, BVT(clib_bihash) );
	int verbose = va_arg (*args, int);
	clib_bihash_bucket_t * b;
	BVT(clib_bihash_value) * v;
	int i, j, k;
	u64 active_elements = 0;

	s = format (s, "Hash table %s\n", h->name ? h->name : (u8 *) "(unnamed)");

	for (i = 0; i < h->nbuckets; i++)
	{
	b = &h->buckets [i];
	if (b->offset == 0)
	{
	if (verbose > 1)
	s = format (s, "[%d]: empty\n", i);
	continue;
	}

	if (verbose)
	{
	s = format (s, "[%d]: heap offset %d, len %d\n", i,
	b->offset, (1<<b->log2_pages));
	}

	v = BV(clib_bihash_get_value) (h, b->offset);
	for (j = 0; j < (1<<b->log2_pages); j++)
	{
	for (k = 0; k < BIHASH_KVP_PER_PAGE; k++)
	{
	if (BV(clib_bihash_is_free)(&v->kvp[k]))
	{
	if (verbose > 1)
	s = format (s, " %d: empty\n",
	j * BIHASH_KVP_PER_PAGE + k);
	continue;
	}
	if (verbose)
	{
	s = format (s, " %d: %U\n",
	j * BIHASH_KVP_PER_PAGE + k,
	BV(format_bihash_kvp),
	&(v->kvp[k]));
	}
	active_elements++;
	}
	v++;
	}
	}

	s = format (s, " %lld active elements\n", active_elements);
	s = format (s, " %d free lists\n", vec_len (h->freelists));
	s = format (s, " %U\n", format_mheap, h->mheap, 1 /* verbose */);

	return s;
	}

	void BV(clib_bihash_foreach_key_value_pair)
	(BVT(clib_bihash) * h,
	void *callback,
	void *arg)
	{
	int i, j, k;
	clib_bihash_bucket_t * b;
	BVT(clib_bihash_value) * v;
	void (fp)(BVT(clib_bihash_kv) , void *) = callback;

	for (i = 0; i < h->nbuckets; i++)
	{
	b = &h->buckets [i];
	if (b->offset == 0)
	continue;

	v = BV(clib_bihash_get_value) (h, b->offset);
	for (j = 0; j < (1<<b->log2_pages); j++)
	{
	for (k = 0; k < BIHASH_KVP_PER_PAGE; k++)
	{
	if (BV(clib_bihash_is_free)(&v->kvp[k]))
	continue;

	(*fp)(&v->kvp[k], arg);
	}
	v++;
	}
	}
	}