/*
  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
#undef HAVE_MEMFD_CREATE
#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

#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)

#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 at alloc_arena_next.
   */
  u64 alloc_arena_next;	/* Next VA to allocate, definitely NOT a constant */
  u64 alloc_arena_size;	/* Size of the arena */
  u64 alloc_arena;	/* Base VA of 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;
}) BVT (clib_bihash_shared_header);
/* *INDENT-ON* */

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

typedef struct
{
  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;
  u8 *name;

  u64 *freelists;

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

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

} BVT (clib_bihash);

#if BIHASH_32_64_SVM
#undef alloc_arena_next
#undef alloc_arena_size
#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(h) (((h)->sh)->alloc_arena)
#define CLIB_BIHASH_READY_MAGIC 0xFEEDFACE
#else
#undef alloc_arena_next
#undef alloc_arena_size
#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(h) ((h)->sh.alloc_arena)
#define CLIB_BIHASH_READY_MAGIC 0
#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)
{
  BVT (clib_bihash_bucket) unlocked_bucket, locked_bucket;

  do
    {
      locked_bucket.as_u64 = unlocked_bucket.as_u64 = b->as_u64;
      unlocked_bucket.lock = 0;
      locked_bucket.lock = 1;
      CLIB_PAUSE ();
    }
  while (__atomic_compare_exchange_n (&b->as_u64, &unlocked_bucket.as_u64,
				      locked_bucket.as_u64, 1 /* weak */ ,
				      __ATOMIC_ACQUIRE,
				      __ATOMIC_ACQUIRE) == 0);
}

static inline void BV (clib_bihash_unlock_bucket)
  (BVT (clib_bihash_bucket) * b)
{
  CLIB_MEMORY_BARRIER ();
  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 */
  return b->offset == 0;
}

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;
}

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

#if BIHASH_32_64_SVM
void BV (clib_bihash_master_init_svm)
  (BVT (clib_bihash) * h, char *name, u32 nbuckets,
   u64 base_address, u64 memory_size);
void BV (clib_bihash_slave_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 * 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_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_search) (BVT (clib_bihash) * h,
			     BVT (clib_bihash_kv) * search_v,
			     BVT (clib_bihash_kv) * return_v);

void BV (clib_bihash_foreach_key_value_pair) (BVT (clib_bihash) * h,
					      void *callback, void *arg);

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

static inline int BV (clib_bihash_search_inline_with_hash)
  (BVT (clib_bihash) * h, u64 hash, BVT (clib_bihash_kv) * key_result)
{
  u32 bucket_index;
  BVT (clib_bihash_value) * v;
  BVT (clib_bihash_bucket) * b;
  int i, limit;

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

  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 ();
    }

  hash >>= h->log2_nbuckets;

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

  /* If the bucket has unresolvable collisions, use linear search */
  limit = BIHASH_KVP_PER_PAGE;
  v += (b->linear_search == 0) ? hash & ((1 << b->log2_pages) - 1) : 0;
  if (PREDICT_FALSE (b->linear_search))
    limit <<= 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)
{
  u32 bucket_index;
  BVT (clib_bihash_bucket) * b;

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

  CLIB_PREFETCH (b, CLIB_CACHE_LINE_BYTES, READ);
}

static inline void BV (clib_bihash_prefetch_data)
  (BVT (clib_bihash) * h, u64 hash)
{
  u32 bucket_index;
  BVT (clib_bihash_value) * v;
  BVT (clib_bihash_bucket) * b;

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

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

  hash >>= h->log2_nbuckets;
  v = BV (clib_bihash_get_value) (h, b->offset);

  v += (b->linear_search == 0) ? hash & ((1 << b->log2_pages) - 1) : 0;

  CLIB_PREFETCH (v, CLIB_CACHE_LINE_BYTES, READ);
}

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)
{
  u32 bucket_index;
  BVT (clib_bihash_value) * v;
  BVT (clib_bihash_bucket) * b;
  int i, limit;

  ASSERT (valuep);

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

  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 ();
    }

  hash >>= h->log2_nbuckets;
  v = BV (clib_bihash_get_value) (h, b->offset);

  /* If the bucket has unresolvable collisions, use linear search */
  limit = BIHASH_KVP_PER_PAGE;
  v += (b->linear_search == 0) ? hash & ((1 << b->log2_pages) - 1) : 0;
  if (PREDICT_FALSE (b->linear_search))
    limit <<= 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:
 */

ss="n">i++)
    if (vls->workers_subscribed[i] == wrk_index)
      return 1;
  return 0;
}

static void
vls_listener_wrk_set (vcl_locked_session_t * vls, u32 wrk_index, u8 is_active)
{
  clib_bitmap_set (vls->listeners, wrk_index, is_active);
}

static u8
vls_listener_wrk_is_active (vcl_locked_session_t * vls, u32 wrk_index)
{
  return (clib_bitmap_get (vls->listeners, wrk_index) == 1);
}

static void
vls_listener_wrk_start_listen (vcl_locked_session_t * vls, u32 wrk_index)
{
  vppcom_session_listen (vls_to_sh (vls), ~0);
  vls_listener_wrk_set (vls, wrk_index, 1 /* is_active */ );
}

static void
vls_listener_wrk_stop_listen (vcl_locked_session_t * vls, u32 wrk_index)
{
  vcl_worker_t *wrk;
  vcl_session_t *s;

  wrk = vcl_worker_get (wrk_index);
  s = vcl_session_get (wrk, vls->session_index);
  if (s->session_state != STATE_LISTEN)
    return;
  vppcom_send_unbind_sock (wrk, s->vpp_handle);
  s->session_state = STATE_LISTEN_NO_MQ;
  vls_listener_wrk_set (vls, wrk_index, 0 /* is_active */ );
}

int
vls_unshare_session (vcl_locked_session_t * vls, vcl_worker_t * wrk)
{
  int i, do_disconnect;
  vcl_session_t *s;

  s = vcl_session_get (wrk, vls->session_index);
  if (s->session_state == STATE_LISTEN)
    vls_listener_wrk_set (vls, wrk->wrk_index, 0 /* is_active */ );

  for (i = 0; i < vec_len (vls->workers_subscribed); i++)
    {
      if (vls->workers_subscribed[i] != wrk->wrk_index)
	continue;

      if (s->rx_fifo)
	{
	  svm_fifo_del_subscriber (s->rx_fifo, wrk->vpp_wrk_index);
	  svm_fifo_del_subscriber (s->tx_fifo, wrk->vpp_wrk_index);
	}
      vec_del1 (vls->workers_subscribed, i);
      do_disconnect = s->session_state == STATE_LISTEN;
      vcl_session_cleanup (wrk, s, vcl_session_handle (s), do_disconnect);
      return 0;
    }

  /* Return, if this is not the owning worker */
  if (vls->worker_index != wrk->wrk_index)
    return 0;

  /* Check if we can change owner or close */
  if (vec_len (vls->workers_subscribed))
    {
      vls->worker_index = vls->workers_subscribed[0];
      vec_del1 (vls->workers_subscribed, 0);
      vcl_send_session_worker_update (wrk, s, vls->worker_index);
      if (vec_len (vls->workers_subscribed))
	clib_warning ("more workers need to be updated");
    }
  else
    {
      vcl_session_cleanup (wrk, s, vcl_session_handle (s),
			   1 /* do_disconnect */ );
    }

  return 0;
}

void
vls_share_vcl_session (vcl_worker_t * wrk, vcl_session_t * s)
{
  vcl_locked_session_t *vls;

  vls = vls_get (vls_si_to_vlsh (s->session_index));
  if (!vls)
    return;
  vls_lock (vls);
  vec_add1 (vls->workers_subscribed, wrk->wrk_index);
  if (s->rx_fifo)
    {
      svm_fifo_add_subscriber (s->rx_fifo, wrk->vpp_wrk_index);
      svm_fifo_add_subscriber (s->tx_fifo, wrk->vpp_wrk_index);
    }
  else if (s->session_state == STATE_LISTEN)
    {
      s->session_state = STATE_LISTEN_NO_MQ;
    }

  vls_unlock (vls);
}

void
vls_worker_copy_on_fork (vcl_worker_t * parent_wrk)
{
  vcl_worker_t *wrk = vcl_worker_get_current ();
  vcl_session_t *s;

  wrk->vpp_event_queues = vec_dup (parent_wrk->vpp_event_queues);
  wrk->sessions = pool_dup (parent_wrk->sessions);
  wrk->session_index_by_vpp_handles =
    hash_dup (parent_wrk->session_index_by_vpp_handles);
  vls_table_rlock ();

  /* *INDENT-OFF* */
  pool_foreach (s, wrk->sessions, ({
    vls_share_vcl_session (wrk, s);
  }));
  /* *INDENT-ON* */

  vls_table_runlock ();
}

static void
vls_mt_acq_locks (vcl_locked_session_t * vls, vls_mt_ops_t op, int *locks_acq)
{
  vcl_worker_t *wrk = vcl_worker_get_current ();
  vcl_session_t *s = 0;
  int is_nonblk = 0;

  if (vls)
    {
      s = vcl_session_get (wrk, vls->session_index);
      if (PREDICT_FALSE (!s))
	return;
      is_nonblk = VCL_SESS_ATTR_TEST (s->attr, VCL_SESS_ATTR_NONBLOCK);
    }

  switch (op)
    {
    case VLS_MT_OP_READ:
      if (!is_nonblk)
	is_nonblk = vcl_session_read_ready (s) != 0;
      if (!is_nonblk)
	{
	  vls_mt_mq_lock ();
	  *locks_acq |= VLS_MT_LOCK_MQ;
	}
      break;
    case VLS_MT_OP_WRITE:
      ASSERT (s);
      if (!is_nonblk)
	is_nonblk = vcl_session_write_ready (s) != 0;
      if (!is_nonblk)
	{
	  vls_mt_mq_lock ();
	  *locks_acq |= VLS_MT_LOCK_MQ;
	}
      break;
    case VLS_MT_OP_XPOLL:
      vls_mt_mq_lock ();
      *locks_acq |= VLS_MT_LOCK_MQ;
      break;
    case VLS_MT_OP_SPOOL:
      vls_mt_spool_lock ();
      *locks_acq |= VLS_MT_LOCK_SPOOL;
      break;
    default:
      break;
    }
}

static void
vls_mt_rel_locks (int locks_acq)
{
  if (locks_acq & VLS_MT_LOCK_MQ)
    vls_mt_mq_unlock ();
  if (locks_acq & VLS_MT_LOCK_SPOOL)
    vls_mt_create_unlock ();
}

#define vls_mt_guard(_vls, _op)				\
  int _locks_acq = 0;					\
  if (PREDICT_FALSE (vcl_get_worker_index () == ~0))	\
    vls_mt_add ();					\
  if (PREDICT_FALSE (vlsl->vls_mt_n_threads > 1))	\
    vls_mt_acq_locks (_vls, _op, &_locks_acq);		\

#define vls_mt_unguard()				\
  if (PREDICT_FALSE (_locks_acq))			\
    vls_mt_rel_locks (_locks_acq)

int
vls_write (vls_handle_t vlsh, void *buf, size_t nbytes)
{
  vcl_locked_session_t *vls;
  int rv;

  if (!(vls = vls_get_w_dlock (vlsh)))
    return VPPCOM_EBADFD;

  vls_mt_guard (vls, VLS_MT_OP_WRITE);
  rv = vppcom_session_write (vls_to_sh_tu (vls), buf, nbytes);
  vls_mt_unguard ();
  vls_get_and_unlock (vlsh);
  return rv;
}

int
vls_write_msg (vls_handle_t vlsh, void *buf, size_t nbytes)
{
  vcl_locked_session_t *vls;
  int rv;

  if (!(vls = vls_get_w_dlock (vlsh)))
    return VPPCOM_EBADFD;
  vls_mt_guard (vls, VLS_MT_OP_WRITE);
  rv = vppcom_session_write_msg (vls_to_sh_tu (vls), buf, nbytes);
  vls_mt_unguard ();
  vls_get_and_unlock (vlsh);
  return rv;
}

int
vls_sendto (vls_handle_t vlsh, void *buf, int buflen, int flags,
	    vppcom_endpt_t * ep)
{
  vcl_locked_session_t *vls;
  int rv;

  if (!(vls = vls_get_w_dlock (vlsh)))
    return VPPCOM_EBADFD;
  vls_mt_guard (vls, VLS_MT_OP_WRITE);
  rv = vppcom_session_sendto (vls_to_sh_tu (vls), buf, buflen, flags, ep);
  vls_mt_unguard ();
  vls_get_and_unlock (vlsh);
  return rv;
}

ssize_t
vls_read (vls_handle_t vlsh, void *buf, size_t nbytes)
{
  vcl_locked_session_t *vls;
  int rv;

  if (!(vls = vls_get_w_dlock (vlsh)))
    return VPPCOM_EBADFD;
  vls_mt_guard (vls, VLS_MT_OP_READ);
  rv = vppcom_session_read (vls_to_sh_tu (vls), buf, nbytes);
  vls_mt_unguard ();
  vls_get_and_unlock (vlsh);
  return rv;
}

ssize_t
vls_recvfrom (vls_handle_t vlsh, void *buffer, uint32_t buflen, int flags,
	      vppcom_endpt_t * ep)
{
  vcl_locked_session_t *vls;
  int rv;

  if (!(vls = vls_get_w_dlock (vlsh)))
    return VPPCOM_EBADFD;
  vls_mt_guard (vls, VLS_MT_OP_READ);
  rv = vppcom_session_recvfrom (vls_to_sh_tu (vls), buffer, buflen, flags,
				ep);
  vls_mt_unguard ();
  vls_get_and_unlock (vlsh);
  return rv;
}

int
vls_attr (vls_handle_t vlsh, uint32_t op, void *buffer, uint32_t * buflen)
{
  vcl_locked_session_t *vls;
  int rv;

  if (PREDICT_FALSE (vcl_get_worker_index () == ~0))
    vls_mt_add ();

  if (!(vls = vls_get_w_dlock (vlsh)))
    return VPPCOM_EBADFD;
  rv = vppcom_session_attr (vls_to_sh_tu (vls), op, buffer, buflen);
  vls_get_and_unlock (vlsh);
  return rv;
}

int
vls_bind (vls_handle_t vlsh, vppcom_endpt_t * ep)
{
  vcl_locked_session_t *vls;
  int rv;

  if (!(vls = vls_get_w_dlock (vlsh)))
    return VPPCOM_EBADFD;
  rv = vppcom_session_bind (vls_to_sh_tu (vls), ep);
  vls_get_and_unlock (vlsh);
  return rv;
}

int
vls_listen (vls_handle_t vlsh, int q_len)
{
  vcl_locked_session_t *vls;
  int rv;

  if (!(vls = vls_get_w_dlock (vlsh)))
    return VPPCOM_EBADFD;
  vls_mt_guard (vls, VLS_MT_OP_XPOLL);
  rv = vppcom_session_listen (vls_to_sh_tu (vls), q_len);
  vls_mt_unguard ();
  vls_get_and_unlock (vlsh);
  return rv;
}

int
vls_connect (vls_handle_t vlsh, vppcom_endpt_t * server_ep)
{
  vcl_locked_session_t *vls;
  int rv;

  if (!(vls = vls_get_w_dlock (vlsh)))
    return VPPCOM_EBADFD;
  vls_mt_guard (vls, VLS_MT_OP_XPOLL);
  rv = vppcom_session_connect (vls_to_sh_tu (vls), server_ep);
  vls_mt_unguard ();
  vls_get_and_unlock (vlsh);
  return rv;
}

static inline void
vls_mp_checks (vcl_locked_session_t * vls, int is_add)
{
  vcl_worker_t *wrk = vcl_worker_get_current ();
  vcl_session_t *s;

  s = vcl_session_get (wrk, vls->session_index);
  switch (s->session_state)
    {
    case STATE_LISTEN:
      if (is_add)
	{
	  if (vls->worker_index == wrk->wrk_index)
	    vls_listener_wrk_set (vls, wrk->wrk_index, 1 /* is_active */ );
	  break;
	}
      vls_listener_wrk_stop_listen (vls, vls->worker_index);
      break;
    case STATE_LISTEN_NO_MQ:
      if (!is_add)
	break;

      /* Register worker as listener */
      vls_listener_wrk_start_listen (vls, wrk->wrk_index);

      /* If owner worker did not attempt to accept/xpoll on the session,
       * force a listen stop for it, since it may not be interested in
       * accepting new sessions.
       * This is pretty much a hack done to give app workers the illusion
       * that it is fine to listen and not accept new sessions for a
       * given listener. Without it, we would accumulate unhandled
       * accepts on the passive worker message queue. */
      if (!vls_listener_wrk_is_active (vls, vls->worker_index))
	vls_listener_wrk_stop_listen (vls, vls->worker_index);
      break;
    default:
      break;
    }
}

vls_handle_t
vls_accept (vls_handle_t listener_vlsh, vppcom_endpt_t * ep, int flags)
{
  vls_handle_t accepted_vlsh;
  vcl_locked_session_t *vls;
  int sh;

  if (!(vls = vls_get_w_dlock (listener_vlsh)))
    return VPPCOM_EBADFD;
  if (vcl_n_workers () > 1)
    vls_mp_checks (vls, 1 /* is_add */ );
  vls_mt_guard (vls, VLS_MT_OP_SPOOL);
  sh = vppcom_session_accept (vls_to_sh_tu (vls), ep, flags);
  vls_mt_unguard ();
  vls_get_and_unlock (listener_vlsh);
  if (sh < 0)
    return sh;
  accepted_vlsh = vls_alloc (sh);
  if (PREDICT_FALSE (accepted_vlsh == VLS_INVALID_HANDLE))
    vppcom_session_close (sh);
  return accepted_vlsh;
}

vls_handle_t
vls_create (uint8_t proto, uint8_t is_nonblocking)
{
  vcl_session_handle_t sh;
  vls_handle_t vlsh;

  vls_mt_guard (0, VLS_MT_OP_SPOOL);
  sh = vppcom_session_create (proto, is_nonblocking);
  vls_mt_unguard ();
  if (sh == INVALID_SESSION_ID)
    return VLS_INVALID_HANDLE;

  vlsh = vls_alloc (sh);
  if (PREDICT_FALSE (vlsh == VLS_INVALID_HANDLE))
    vppcom_session_close (sh);

  return vlsh;
}

int
vls_close (vls_handle_t vlsh)
{
  vcl_locked_session_t *vls;
  int rv;

  vls_table_wlock ();

  vls = vls_get_and_lock (vlsh);
  if (!vls)
    {
      vls_table_wunlock ();
      return VPPCOM_EBADFD;
    }

  vls_mt_guard (0, VLS_MT_OP_SPOOL);
  if (vls_is_shared (vls))
    {
      /* At least two workers share the session so vls won't be freed */
      vls_unshare_session (vls, vcl_worker_get_current ());
      vls_unlock (vls);
      vls_mt_unguard ();
      vls_table_wunlock ();
      return VPPCOM_OK;
    }

  rv = vppcom_session_close (vls_to_sh (vls));
  vls_free (vls);
  vls_mt_unguard ();

  vls_table_wunlock ();

  return rv;
}

vls_handle_t
vls_epoll_create (void)
{
  vcl_session_handle_t sh;
  vls_handle_t vlsh;

  if (PREDICT_FALSE (vcl_get_worker_index () == ~0))
    vls_mt_add ();

  sh = vppcom_epoll_create ();
  if (sh == INVALID_SESSION_ID)
    return VLS_INVALID_HANDLE;

  vlsh = vls_alloc (sh);
  if (vlsh == VLS_INVALID_HANDLE)
    vppcom_session_close (sh);

  return vlsh;
}

static void
vls_epoll_ctl_mp_checks (vcl_locked_session_t * vls, int op)
{
  if (vcl_n_workers () <= 1)
    {
      vlsl->epoll_mp_check = 1;
      return;
    }

  if (op == EPOLL_CTL_MOD)
    return;

  vlsl->epoll_mp_check = 1;
  vls_mp_checks (vls, op == EPOLL_CTL_ADD);
}

int
vls_epoll_ctl (vls_handle_t ep_vlsh, int op, vls_handle_t vlsh,
	       struct epoll_event *event)
{
  vcl_locked_session_t *ep_vls, *vls;
  vcl_session_handle_t ep_sh, sh;
  int rv;

  vls_table_rlock ();
  ep_vls = vls_get_and_lock (ep_vlsh);
  vls = vls_get_and_lock (vlsh);
  ep_sh = vls_to_sh (ep_vls);
  sh = vls_to_sh (vls);

  if (PREDICT_FALSE (!vlsl->epoll_mp_check))
    vls_epoll_ctl_mp_checks (vls, op);

  vls_table_runlock ();

  rv = vppcom_epoll_ctl (ep_sh, op, sh, event);

  vls_table_rlock ();
  ep_vls = vls_get (ep_vlsh);
  vls = vls_get (vlsh);
  vls_unlock (vls);
  vls_unlock (ep_vls);
  vls_table_runlock ();
  return rv;
}

int
vls_epoll_wait (vls_handle_t ep_vlsh, struct epoll_event *events,
		int maxevents, double wait_for_time)
{
  vcl_locked_session_t *vls;
  int rv;

  if (!(vls = vls_get_w_dlock (ep_vlsh)))
    return VPPCOM_EBADFD;
  vls_mt_guard (0, VLS_MT_OP_XPOLL);
  rv = vppcom_epoll_wait (vls_to_sh_tu (vls), events, maxevents,
			  wait_for_time);
  vls_mt_unguard ();
  vls_get_and_unlock (ep_vlsh);
  return rv;
}

static void
vls_select_mp_checks (vcl_si_set * read_map)
{
  vcl_locked_session_t *vls;
  vcl_worker_t *wrk;
  vcl_session_t *s;
  u32 si;

  if (vcl_n_workers () <= 1)
    {
      vlsl->select_mp_check = 1;
      return;
    }

  if (!read_map)
    return;

  vlsl->select_mp_check = 1;
  wrk = vcl_worker_get_current ();

  /* *INDENT-OFF* */
  clib_bitmap_foreach (si, read_map, ({
    s = vcl_session_get (wrk, si);
    if (s->session_state == STATE_LISTEN)
      {
	vls = vls_get (vls_session_index_to_vlsh (si));
	vls_mp_checks (vls, 1 /* is_add */);
      }
  }));
  /* *INDENT-ON* */
}

int
vls_select (int n_bits, vcl_si_set * read_map, vcl_si_set * write_map,
	    vcl_si_set * except_map, double wait_for_time)
{
  int rv;

  vls_mt_guard (0, VLS_MT_OP_XPOLL);
  if (PREDICT_FALSE (!vlsl->select_mp_check))
    vls_select_mp_checks (read_map);
  rv = vppcom_select (n_bits, read_map, write_map, except_map, wait_for_time);
  vls_mt_unguard ();
  return rv;
}

static void
vls_unshare_vcl_worker_sessions (vcl_worker_t * wrk)
{
  u32 current_wrk, is_current;
  vcl_locked_session_t *vls;
  vcl_session_t *s;

  if (pool_elts (vcm->workers) <= 1)
    return;

  current_wrk = vcl_get_worker_index ();
  is_current = current_wrk == wrk->wrk_index;
  vls_table_wlock ();

  /* *INDENT-OFF* */
  pool_foreach (s, wrk->sessions, ({
    vls = vls_get (vls_si_to_vlsh (s->session_index));
    if (vls && (is_current || vls_is_shared_by_wrk (vls, current_wrk)))
      vls_unshare_session (vls, wrk);
  }));
  /* *INDENT-ON* */

  vls_table_wunlock ();
}

static void
vls_cleanup_vcl_worker (vcl_worker_t * wrk)
{
  /* Unshare sessions and also cleanup worker since child may have
   * called _exit () and therefore vcl may not catch the event */
  vls_unshare_vcl_worker_sessions (wrk);
  vcl_worker_cleanup (wrk, 1 /* notify vpp */ );
}

static void
vls_cleanup_forked_child (vcl_worker_t * wrk, vcl_worker_t * child_wrk)
{
  vcl_worker_t *sub_child;
  int tries = 0;

  if (child_wrk->forked_child != ~0)
    {
      sub_child = vcl_worker_get_if_valid (child_wrk->forked_child);
      if (sub_child)
	{
	  /* Wait a bit, maybe the process is going away */
	  while (kill (sub_child->current_pid, 0) >= 0 && tries++ < 50)
	    usleep (1e3);
	  if (kill (sub_child->current_pid, 0) < 0)
	    vls_cleanup_forked_child (child_wrk, sub_child);
	}
    }
  vls_cleanup_vcl_worker (child_wrk);
  VDBG (0, "Cleaned up forked child wrk %u", child_wrk->wrk_index);
  wrk->forked_child = ~0;
}

static struct sigaction old_sa;

static void
vls_intercept_sigchld_handler (int signum, siginfo_t * si, void *uc)
{
  vcl_worker_t *wrk, *child_wrk;

  if (vcl_get_worker_index () == ~0)
    return;

  if (sigaction (SIGCHLD, &old_sa, 0))
    {
      VERR ("couldn't restore sigchld");
      exit (-1);
    }

  wrk = vcl_worker_get_current ();
  if (wrk->forked_child == ~0)
    return;

  child_wrk = vcl_worker_get_if_valid (wrk->forked_child);
  if (!child_wrk)
    goto done;

  if (si && si->si_pid != child_wrk->current_pid)
    {
      VDBG (0, "unexpected child pid %u", si->si_pid);
      goto done;
    }
  vls_cleanup_forked_child (wrk, child_wrk);

done:
  if (old_sa.sa_flags & SA_SIGINFO)
    {
      void (*fn) (int, siginfo_t *, void *) = old_sa.sa_sigaction;
      fn (signum, si, uc);
    }
  else
    {
      void (*fn) (int) = old_sa.sa_handler;
      if (fn)
	fn (signum);
    }
}

static void
vls_incercept_sigchld ()
{
  struct sigaction sa;
  clib_memset (&sa, 0, sizeof (sa));
  sa.sa_sigaction = vls_intercept_sigchld_handler;
  sa.sa_flags = SA_SIGINFO;
  if (sigaction (SIGCHLD, &sa, &old_sa))
    {
      VERR ("couldn't intercept sigchld");
      exit (-1);
    }
}

static void
vls_app_pre_fork (void)
{
  vls_incercept_sigchld ();
  vcl_flush_mq_events ();
}

static void
vls_app_fork_child_handler (void)
{
  vcl_worker_t *parent_wrk;
  int rv, parent_wrk_index;
  u8 *child_name;

  parent_wrk_index = vcl_get_worker_index ();
  VDBG (0, "initializing forked child %u with parent wrk %u", getpid (),
	parent_wrk_index);

  /*
   * Allocate worker
   */
  vcl_set_worker_index (~0);
  if (!vcl_worker_alloc_and_init ())
    VERR ("couldn't allocate new worker");

  /*
   * Attach to binary api
   */
  child_name = format (0, "%v-child-%u%c", vcm->app_name, getpid (), 0);
  vcl_cleanup_bapi ();
  vppcom_api_hookup ();
  vcm->app_state = STATE_APP_START;
  rv = vppcom_connect_to_vpp ((char *) child_name);
  vec_free (child_name);
  if (rv)
    {
      VERR ("couldn't connect to VPP!");
      return;
    }

  /*
   * Register worker with vpp and share sessions
   */
  vcl_worker_register_with_vpp ();
  parent_wrk = vcl_worker_get (parent_wrk_index);
  vls_worker_copy_on_fork (parent_wrk);
  parent_wrk->forked_child = vcl_get_worker_index ();

  /* Reset number of threads and set wrk index */
  vlsl->vls_mt_n_threads = 0;
  vlsl->vls_wrk_index = vcl_get_worker_index ();
  vlsl->select_mp_check = 0;
  vlsl->epoll_mp_check = 0;
  vls_mt_locks_init ();

  VDBG (0, "forked child main worker initialized");
  vcm->forking = 0;
}

static void
vls_app_fork_parent_handler (void)
{
  vcm->forking = 1;
  while (vcm->forking)
    ;
}

void
vls_app_exit (void)
{
  /* Unshare the sessions. VCL will clean up the worker */
  vls_unshare_vcl_worker_sessions (vcl_worker_get_current ());
}

int
vls_app_create (char *app_name)
{
  int rv;

  if ((rv = vppcom_app_create (app_name)))
    return rv;
  vlsm = clib_mem_alloc (sizeof (vls_main_t));
  clib_memset (vlsm, 0, sizeof (*vlsm));
  clib_rwlock_init (&vlsm->vls_table_lock);
  pthread_atfork (vls_app_pre_fork, vls_app_fork_parent_handler,
		  vls_app_fork_child_handler);
  atexit (vls_app_exit);
  vlsl->vls_wrk_index = vcl_get_worker_index ();
  vls_mt_locks_init ();
  return VPPCOM_OK;
}

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