/*
 * 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.
 */
/*
  Copyright (c) 2001, 2002, 2003, 2004 Eliot Dresselhaus

  Permission is hereby granted, free of charge, to any person obtaining
  a copy of this software and associated documentation files (the
  "Software"), to deal in the Software without restriction, including
  without limitation the rights to use, copy, modify, merge, publish,
  distribute, sublicense, and/or sell copies of the Software, and to
  permit persons to whom the Software is furnished to do so, subject to
  the following conditions:

  The above copyright notice and this permission notice shall be
  included in all copies or substantial portions of the Software.

  THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
  EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
  MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
  NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
  LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
  OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
  WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
*/
/** @file
 * @brief Fixed length block allocator.
   Pools are built from clib vectors and bitmaps. Use pools when
   repeatedly allocating and freeing fixed-size data. Pools are
   fast, and avoid memory fragmentation.
 */

#ifndef included_pool_h
#define included_pool_h

#include <vppinfra/bitmap.h>
#include <vppinfra/error.h>
#include <vppinfra/mheap.h>


typedef struct
{
  /** Bitmap of indices of free objects. */
  uword *free_bitmap;

  /** Vector of free indices.  One element for each set bit in bitmap. */
  u32 *free_indices;

  /* The following fields are set for fixed-size, preallocated pools */

  /** Maximum size of the pool, in elements */
  u32 max_elts;

  /** mmap segment info: base + length */
  u8 *mmap_base;
  u64 mmap_size;

} pool_header_t;

/** Align pool header so that pointers are naturally aligned. */
#define pool_aligned_header_bytes \
  vec_aligned_header_bytes (sizeof (pool_header_t), sizeof (void *))

/** Get pool header from user pool pointer */
always_inline pool_header_t *
pool_header (void *v)
{
  return vec_aligned_header (v, sizeof (pool_header_t), sizeof (void *));
}

extern void _pool_init_fixed (void **, u32, u32);
extern void fpool_free (void *);

/** initialize a fixed-size, preallocated pool */
#define pool_init_fixed(pool,max_elts)                  \
{                                                       \
  _pool_init_fixed((void **)&(pool),sizeof(pool[0]),max_elts);  \
}

/** Validate a pool */
always_inline void
pool_validate (void *v)
{
  pool_header_t *p = pool_header (v);
  uword i, n_free_bitmap;

  if (!v)
    return;

  n_free_bitmap = clib_bitmap_count_set_bits (p->free_bitmap);
  ASSERT (n_free_bitmap == vec_len (p->free_indices));
  for (i = 0; i < vec_len (p->free_indices); i++)
    ASSERT (clib_bitmap_get (p->free_bitmap, p->free_indices[i]) == 1);
}

always_inline void
pool_header_validate_index (void *v, uword index)
{
  pool_header_t *p = pool_header (v);

  if (v)
    vec_validate (p->free_bitmap, index / BITS (uword));
}

#define pool_validate_index(v,i)				\
do {								\
  uword __pool_validate_index = (i);				\
  vec_validate_ha ((v), __pool_validate_index,			\
		   pool_aligned_header_bytes, /* align */ 0);   \
  pool_header_validate_index ((v), __pool_validate_index);	\
} while (0)

/** Number of active elements in a pool.
 * @return Number of active elements in a pool
 */
always_inline uword
pool_elts (void *v)
{
  uword ret = vec_len (v);
  if (v)
    ret -= vec_len (pool_header (v)->free_indices);
  return ret;
}

/** Number of elements in pool vector.

    @note You probably want to call pool_elts() instead.
*/
#define pool_len(p)	vec_len(p)

/** Number of elements in pool vector (usable as an lvalue)

    @note You probably don't want to use this macro.
*/
#define _pool_len(p)	_vec_len(p)

/** Memory usage of pool header. */
always_inline uword
pool_header_bytes (void *v)
{
  pool_header_t *p = pool_header (v);

  if (!v)
    return 0;

  return vec_bytes (p->free_bitmap) + vec_bytes (p->free_indices);
}

/** Memory usage of pool. */
#define pool_bytes(P) (vec_bytes (P) + pool_header_bytes (P))

/** Local variable naming macro. */
#define _pool_var(v) _pool_##v

/** Queries whether pool has at least N_FREE free elements. */
always_inline uword
pool_free_elts (void *v)
{
  pool_header_t *p = pool_header (v);
  uword n_free = 0;

  if (v)
    {
      n_free += vec_len (p->free_indices);

      /* Space left at end of vector? */
      n_free += vec_capacity (v, sizeof (p[0])) - vec_len (v);
    }

  return n_free;
}

/** Allocate an object E from a pool P (general version).

   First search free list.  If nothing is free extend vector of objects.
*/
#define pool_get_aligned(P,E,A)                                         \
do {                                                                    \
  pool_header_t * _pool_var (p) = pool_header (P);                      \
  uword _pool_var (l);                                                  \
                                                                        \
  STATIC_ASSERT(A==0 || ((A % sizeof(P[0]))==0) || ((sizeof(P[0]) % A) == 0), \
                "Pool aligned alloc of incorrectly sized object");      \
  _pool_var (l) = 0;                                                    \
  if (P)                                                                \
    _pool_var (l) = vec_len (_pool_var (p)->free_indices);              \
                                                                        \
  if (_pool_var (l) > 0)                                                \
    {                                                                   \
      /* Return free element from free list. */                         \
      uword _pool_var (i) = _pool_var (p)->free_indices[_pool_var (l) - 1]; \
      (E) = (P) + _pool_var (i);                                        \
      _pool_var (p)->free_bitmap =					\
	clib_bitmap_andnoti_notrim (_pool_var (p)->free_bitmap,        \
	                             _pool_var (i));	               	\
      _vec_len (_pool_var (p)->free_indices) = _pool_var (l) - 1;       \
    }                                                                   \
  else                                                                  \
    {                                                                   \
      /* fixed-size, preallocated pools cannot expand */                \
      if ((P) && _pool_var(p)->max_elts)                                \
        {                                                               \
          clib_warning ("can't expand fixed-size pool");                \
          os_out_of_memory();                                           \
        }                                                               \
      /* Nothing on free list, make a new element and return it. */     \
      P = _vec_resize (P,                                               \
		       /* length_increment */ 1,                        \
		       /* new size */ (vec_len (P) + 1) * sizeof (P[0]), \
		       pool_aligned_header_bytes,                       \
		       /* align */ (A));                                \
      E = vec_end (P) - 1;                                              \
    }									\
} while (0)

/** Allocate an object E from a pool P (unspecified alignment). */
#define pool_get(P,E) pool_get_aligned(P,E,0)

/** See if pool_get will expand the pool or not */
#define pool_get_aligned_will_expand(P,YESNO,A)                         \
do {                                                                    \
  pool_header_t * _pool_var (p) = pool_header (P);                      \
  uword _pool_var (l);                                                  \
                                                                        \
  _pool_var (l) = 0;                                                    \
  if (P)                                                                \
    {                                                                   \
      if (_pool_var (p)->max_elts)                                      \
        _pool_var (l) = _pool_var (p)->max_elts;			\
      else								\
        _pool_var (l) = vec_len (_pool_var (p)->free_indices);          \
    }                                                                   \
                                                                        \
  /* Free elements, certainly won't expand */                           \
  if (_pool_var (l) > 0)                                                \
      YESNO=0;                                                          \
  else                                                                  \
    {                                                                   \
      /* Nothing on free list, make a new element and return it. */     \
      YESNO = _vec_resize_will_expand                                   \
        (P,                                                             \
         /* length_increment */ 1,                                      \
         /* new size */ (vec_len (P) + 1) * sizeof (P[0]),              \
         pool_aligned_header_bytes,                                     \
         /* align */ (A));                                              \
    }                                                                   \
} while (0)

#define pool_get_will_expand(P,YESNO) pool_get_aligned_will_expand(P,YESNO,0)

/** Use free bitmap to query whether given element is free. */
#define pool_is_free(P,E)						\
({									\
  pool_header_t * _pool_var (p) = pool_header (P);			\
  uword _pool_var (i) = (E) - (P);					\
  (_pool_var (i) < vec_len (P)) ? clib_bitmap_get (_pool_var (p)->free_bitmap, _pool_i) : 1; \
})

/** Use free bitmap to query whether given index is free */
#define pool_is_free_index(P,I) pool_is_free((P),(P)+(I))

/** Free an object E in pool P. */
#define pool_put(P,E)							\
do {									\
  pool_header_t * _pool_var (p) = pool_header (P);			\
  uword _pool_var (l) = (E) - (P);					\
  ASSERT (vec_is_member (P, E));					\
  ASSERT (! pool_is_free (P, E));					\
									\
  /* Add element to free bitmap and to free list. */			\
  _pool_var (p)->free_bitmap =						\
    clib_bitmap_ori_notrim (_pool_var (p)->free_bitmap,              	\
                             _pool_var (l));	                        \
                                                                        \
  /* Preallocated pool? */                                              \
  if (_pool_var (p)->max_elts)                                          \
    {                                                                   \
      ASSERT(_pool_var(l) < _pool_var (p)->max_elts);                   \
      _pool_var(p)->free_indices[_vec_len(_pool_var(p)->free_indices)] = \
                                 _pool_var(l);                          \
      _vec_len(_pool_var(p)->free_indices) += 1;                        \
    }                                                                   \
  else                                                                  \
    vec_add1 (_pool_var (p)->free_indices, _pool_var (l));		\
} while (0)

/** Free pool element with given index. */
#define pool_put_index(p,i)			\
do {						\
  typeof (p) _e = (p) + (i);			\
  pool_put (p, _e);				\
} while (0)

/** Allocate N more free elements to pool (general version). */
#define pool_alloc_aligned(P,N,A)					\
do {									\
  pool_header_t * _p;							\
                                                                        \
  if ((P))                                                              \
    {                                                                   \
      _p = pool_header (P);                                             \
      if (_p->max_elts)                                                 \
        {                                                               \
           clib_warning ("Can't expand fixed-size pool");		\
           os_out_of_memory();                                          \
        }                                                               \
    }                                                                   \
                                                                        \
  (P) = _vec_resize ((P), 0, (vec_len (P) + (N)) * sizeof (P[0]),	\
		     pool_aligned_header_bytes,				\
		     (A));						\
  _p = pool_header (P);							\
  vec_resize (_p->free_indices, (N));					\
  _vec_len (_p->free_indices) -= (N);					\
} while (0)

/** Allocate N more free elements to pool (unspecified alignment). */
#define pool_alloc(P,N) pool_alloc_aligned(P,N,0)

/** Low-level free pool operator (do not call directly). */
always_inline void *
_pool_free (void *v)
{
  pool_header_t *p = pool_header (v);
  if (!v)
    return v;
  clib_bitmap_free (p->free_bitmap);

  if (p->max_elts)
    {
      int rv;

      rv = munmap (p->mmap_base, p->mmap_size);
      if (rv)
	clib_unix_warning ("munmap");
    }
  else
    {
      vec_free (p->free_indices);
      vec_free_h (v, pool_aligned_header_bytes);
    }
  return 0;
}

/** Free a pool. */
#define pool_free(p) (p) = _pool_free(p)

/** Optimized iteration through pool.

    @param LO pointer to first element in chunk
    @param HI pointer to last element in chunk
    @param POOL pool to iterate across
    @param BODY operation to perform

    Optimized version which assumes that BODY is smart enough to
    process multiple (LOW,HI) chunks. See also pool_foreach().
 */
#define pool_foreach_region(LO,HI,POOL,BODY)				\
do {									\
  uword _pool_var (i), _pool_var (lo), _pool_var (hi), _pool_var (len);	\
  uword _pool_var (bl), * _pool_var (b);				\
  pool_header_t * _pool_var (p);					\
									\
  _pool_var (p) = pool_header (POOL);					\
  _pool_var (b) = (POOL) ? _pool_var (p)->free_bitmap : 0;		\
  _pool_var (bl) = vec_len (_pool_var (b));				\
  _pool_var (len) = vec_len (POOL);					\
  _pool_var (lo) = 0;							\
									\
  for (_pool_var (i) = 0;						\
       _pool_var (i) <= _pool_var (bl);					\
       _pool_var (i)++)							\
    {									\
      uword _pool_var (m), _pool_var (f);				\
      _pool_var (m) = (_pool_var (i) < _pool_var (bl)			\
		       ? _pool_var (b) [_pool_var (i)]			\
		       : 1);						\
      while (_pool_var (m) != 0)					\
	{								\
	  _pool_var (f) = first_set (_pool_var (m));			\
	  _pool_var (hi) = (_pool_var (i) * BITS (_pool_var (b)[0])	\
			    + min_log2 (_pool_var (f)));		\
	  _pool_var (hi) = (_pool_var (i) < _pool_var (bl)		\
			    ? _pool_var (hi) : _pool_var (len));	\
	  _pool_var (m) ^= _pool_var (f);				\
	  if (_pool_var (hi) > _pool_var (lo))				\
	    {								\
	      (LO) = _pool_var (lo);					\
	      (HI) = _pool_var (hi);					\
	      do { BODY; } while (0);					\
	    }								\
	  _pool_var (lo) = _pool_var (hi) + 1;				\
	}								\
    }									\
} while (0)

/** Iterate through pool.

    @param VAR A variable of same type as pool vector to be used as an
               iterator.
    @param POOL The pool to iterate across.
    @param BODY The operation to perform, typically a code block. See
                the example below.

    This macro will call @c BODY with each active pool element.

    It is a bad idea to allocate or free pool element from within
    @c pool_foreach. Build a vector of indices and dispose of them later.
    Or call pool_flush.


    @par Example
    @code{.c}
    proc_t *procs;   // a pool of processes.
    proc_t *proc;    // pointer to one process; used as the iterator.

    pool_foreach (proc, procs, ({
        if (proc->state != PROC_STATE_RUNNING)
            continue;

        // check a running proc in some way
        ...
    }));
    @endcode

    @warning Because @c pool_foreach is a macro, syntax errors can be
    difficult to find inside @c BODY, let alone actual code bugs. One
    can temporarily split a complex @c pool_foreach into a trivial
    @c pool_foreach which builds a vector of active indi
/*
 * Copyright (c) 2019 Cisco and/or its affiliates.
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this
 * 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.
 */

#include <vcl/vcl_locked.h>
#include <vcl/vcl_private.h>

typedef struct vls_shared_data_
{
  clib_spinlock_t lock;
  u32 owner_wrk_index;
  u32 *workers_subscribed;
  clib_bitmap_t *listeners;
} vls_shared_data_t;

typedef struct vcl_locked_session_
{
  clib_spinlock_t lock;
  u32 session_index;
  u32 worker_index;
  u32 vls_index;
  u32 shared_data_index;
  /** VCL session owned by different workers because of migration */
  u32 owner_vcl_wrk_index;
  uword *vcl_wrk_index_to_session_index;
} vcl_locked_session_t;

typedef struct vls_worker_
{
  vcl_locked_session_t *vls_pool;
  uword *session_handle_to_vlsh_table;
  u32 wrk_index;
} vls_worker_t;

typedef struct vls_local_
{
  int vls_wrk_index;
  volatile int vls_mt_n_threads;
  pthread_mutex_t vls_mt_mq_mlock;
  pthread_mutex_t vls_mt_spool_mlock;
  volatile u8 select_mp_check;
  volatile u8 epoll_mp_check;
} vls_process_local_t;

static vls_process_local_t vls_local;
static vls_process_local_t *vlsl = &vls_local;

typedef struct vls_main_
{
  vls_worker_t *workers;
  clib_rwlock_t vls_table_lock;
  /** Pool of data shared by sessions owned by different workers */
  vls_shared_data_t *shared_data_pool;
  clib_rwlock_t shared_data_lock;
} vls_main_t;

vls_main_t *vlsm;

typedef enum vls_rpc_msg_type_
{
  VLS_RPC_CLONE_AND_SHARE,
  VLS_RPC_SESS_CLEANUP,
} vls_rpc_msg_type_e;

typedef struct vls_rpc_msg_
{
  u8 type;
  u8 data[0];
} vls_rpc_msg_t;

typedef struct vls_clone_and_share_msg_
{
  u32 vls_index;		/**< vls to be shared */
  u32 session_index;		/**< vcl session to be shared */
  u32 origin_vls_wrk;		/**< vls worker that initiated the rpc */
  u32 origin_vls_index;		/**< vls session of the originator */
  u32 origin_vcl_wrk;		/**< vcl worker that initiated the rpc */
  u32 origin_session_index;	/**< vcl session of the originator */
} vls_clone_and_share_msg_t;

typedef struct vls_sess_cleanup_msg_
{
  u32 session_index;		/**< vcl session to be cleaned */
  u32 origin_vcl_wrk;		/**< worker that initiated the rpc */
} vls_sess_cleanup_msg_t;

void vls_send_session_cleanup_rpc (vcl_worker_t * wrk,
				   u32 dst_wrk_index, u32 dst_session_index);
void vls_send_clone_and_share_rpc (vcl_worker_t * wrk,
				   vcl_locked_session_t * vls,
				   u32 session_index, u32 vls_wrk_index,
				   u32 dst_wrk_index, u32 dst_vls_index,
				   u32 dst_session_index);


static inline u32
vls_get_worker_index (void)
{
  if (vls_mt_wrk_supported ())
    return vlsl->vls_wrk_index;
  else
    return vcl_get_worker_index ();
}

static u32
vls_shared_data_alloc (void)
{
  vls_shared_data_t *vls_shd;
  u32 shd_index;

  clib_rwlock_writer_lock (&vlsm->shared_data_lock);
  pool_get_zero (vlsm->shared_data_pool, vls_shd);
  clib_spinlock_init (&vls_shd->lock);
  shd_index = vls_shd - vlsm->shared_data_pool;
  clib_rwlock_writer_unlock (&vlsm->shared_data_lock);

  return shd_index;
}

static u32
vls_shared_data_index (vls_shared_data_t * vls_shd)
{
  return vls_shd - vlsm->shared_data_pool;
}

vls_shared_data_t *
vls_shared_data_get (u32 shd_index)
{
  if (pool_is_free_index (vlsm->shared_data_pool, shd_index))
    return 0;
  return pool_elt_at_index (vlsm->shared_data_pool, shd_index);
}

static void
vls_shared_data_free (u32 shd_index)
{
  vls_shared_data_t *vls_shd;

  clib_rwlock_writer_lock (&vlsm->shared_data_lock);
  vls_shd = vls_shared_data_get (shd_index);
  clib_spinlock_free (&vls_shd->lock);
  clib_bitmap_free (vls_shd->listeners);
  vec_free (vls_shd->workers_subscribed);
  pool_put (vlsm->shared_data_pool, vls_shd);
  clib_rwlock_writer_unlock (&vlsm->shared_data_lock);
}

static inline void
vls_shared_data_pool_rlock (void)
{
  clib_rwlock_reader_lock (&vlsm->shared_data_lock);
}

static inline void
vls_shared_data_pool_runlock (void)
{
  clib_rwlock_reader_unlock (&vlsm->shared_data_lock);
}

static inline void
vls_mt_table_rlock (void)
{
  if (vlsl->vls_mt_n_threads > 1)
    clib_rwlock_reader_lock (&vlsm->vls_table_lock);
}

static inline void
vls_mt_table_runlock (void)
{
  if (vlsl->vls_mt_n_threads > 1)
    clib_rwlock_reader_unlock (&vlsm->vls_table_lock);
}

static inline void
vls_mt_table_wlock (void)
{
  if (vlsl->vls_mt_n_threads > 1)
    clib_rwlock_writer_lock (&vlsm->vls_table_lock);
}

static inline void
vls_mt_table_wunlock (void)
{
  if (vlsl->vls_mt_n_threads > 1)
    clib_rwlock_writer_unlock (&vlsm->vls_table_lock);
}

typedef enum
{
  VLS_MT_OP_READ,
  VLS_MT_OP_WRITE,
  VLS_MT_OP_SPOOL,
  VLS_MT_OP_XPOLL,
} vls_mt_ops_t;

typedef enum
{
  VLS_MT_LOCK_MQ = 1 << 0,
  VLS_MT_LOCK_SPOOL = 1 << 1
} vls_mt_lock_type_t;

static void
vls_mt_add (void)
{
  vlsl->vls_mt_n_threads += 1;

  /* If multi-thread workers are supported, for each new thread register a new
   * vcl worker with vpp. Otherwise, all threads use the same vcl worker, so
   * update the vcl worker's thread local worker index variable */
  if (vls_mt_wrk_supported ())
    vls_register_vcl_worker ();
  else
    vcl_set_worker_index (vlsl->vls_wrk_index);
}

static inline void
vls_mt_mq_lock (void)
{
  pthread_mutex_lock (&vlsl->vls_mt_mq_mlock);
}

static inline void
vls_mt_mq_unlock (void)
{
  pthread_mutex_unlock (&vlsl->vls_mt_mq_mlock);
}

static inline void
vls_mt_spool_lock (void)
{
  pthread_mutex_lock (&vlsl->vls_mt_spool_mlock);
}

static inline void
vls_mt_create_unlock (void)
{
  pthread_mutex_unlock (&vlsl->vls_mt_spool_mlock);
}

static void
vls_mt_locks_init (void)
{
  pthread_mutex_init (&vlsl->vls_mt_mq_mlock, NULL);
  pthread_mutex_init (&vlsl->vls_mt_spool_mlock, NULL);
}

u8
vls_is_shared (vcl_locked_session_t * vls)
{
  return (vls->shared_data_index != ~0);
}

static inline void
vls_lock (vcl_locked_session_t * vls)
{
  if ((vlsl->vls_mt_n_threads > 1) || vls_is_shared (vls))
    clib_spinlock_lock (&vls->lock);
}

static inline void
vls_unlock (vcl_locked_session_t * vls)
{
  if ((vlsl->vls_mt_n_threads > 1) || vls_is_shared (vls))
    clib_spinlock_unlock (&vls->lock);
}

static inline vcl_session_handle_t
vls_to_sh (vcl_locked_session_t * vls)
{
  return vcl_session_handle_from_index (vls->session_index);
}

static inline vcl_session_handle_t
vls_to_sh_tu (vcl_locked_session_t * vls)
{
  vcl_session_handle_t sh;
  sh = vls_to_sh (vls);
  vls_mt_table_runlock ();
  return sh;
}

static vls_worker_t *
vls_worker_get_current (void)
{
  return pool_elt_at_index (vlsm->workers, vls_get_worker_index ());
}

static void
vls_worker_alloc (void)
{
  vls_worker_t *wrk;

  pool_get_zero (vlsm->workers, wrk);
  wrk->wrk_index = vcl_get_worker_index ();
}

static void
vls_worker_free (vls_worker_t * wrk)
{
  hash_free (wrk->session_handle_to_vlsh_table);
  pool_free (wrk->vls_pool);
  pool_put (vlsm->workers, wrk);
}

static vls_worker_t *
vls_worker_get (u32 wrk_index)
{
  if (pool_is_free_index (vlsm->workers, wrk_index))
    return 0;
  return pool_elt_at_index (vlsm->workers, wrk_index);
}

static vls_handle_t
vls_alloc (vcl_session_handle_t sh)
{
  vls_worker_t *wrk = vls_worker_get_current ();
  vcl_locked_session_t *vls;

  vls_mt_table_wlock ();

  pool_get_zero (wrk->vls_pool, vls);
  vls->session_index = vppcom_session_index (sh);
  vls->worker_index = vppcom_session_worker (sh);
  vls->vls_index = vls - wrk->vls_pool;
  vls->shared_data_index = ~0;
  hash_set (wrk->session_handle_to_vlsh_table, sh, vls->vls_index);
  if (vls_mt_wrk_supported ())
    {
      hash_set (vls->vcl_wrk_index_to_session_index, vls->worker_index,
		vls->session_index);
      vls->owner_vcl_wrk_index = vls->worker_index;
    }
  clib_spinlock_init (&vls->lock);

  vls_mt_table_wunlock ();
  return vls->vls_index;
}

static vcl_locked_session_t *
vls_get (vls_handle_t vlsh)
{
  vls_worker_t *wrk = vls_worker_get_current ();
  if (pool_is_free_index (wrk->vls_pool, vlsh))
    return 0;
  return pool_elt_at_index (wrk->vls_pool, vlsh);
}

static void
vls_free (vcl_locked_session_t * vls)
{
  vls_worker_t *wrk = vls_worker_get_current ();

  ASSERT (vls != 0);
  hash_unset (wrk->session_handle_to_vlsh_table,
	      vcl_session_handle_from_index (vls->session_index));
  clib_spinlock_free (&vls->lock);
  pool_put (wrk->vls_pool, vls);
}

static vcl_locked_session_t *
vls_get_and_lock (vls_handle_t vlsh)
{
  vls_worker_t *wrk = vls_worker_get_current ();
  vcl_locked_session_t *vls;
  if (pool_is_free_index (wrk->vls_pool, vlsh))
    return 0;
  vls = pool_elt_at_index (wrk->vls_pool, vlsh);
  vls_lock (vls);
  return vls;
}

static vcl_locked_session_t *
vls_get_w_dlock (vls_handle_t vlsh)
{
  vcl_locked_session_t *vls;
  vls_mt_table_rlock ();
  vls = vls_get_and_lock (vlsh);
  if (!vls)
    vls_mt_table_runlock ();
  return vls;
}

static inline void
vls_get_and_unlock (vls_handle_t vlsh)
{
  vcl_locked_session_t *vls;
  vls_mt_table_rlock ();
  vls = vls_get (vlsh);
  vls_unlock (vls);
  vls_mt_table_runlock ();
}

static inline void
vls_dunlock (vcl_locked_session_t * vls)
{
  vls_unlock (vls);
  vls_mt_table_runlock ();
}

static vcl_locked_session_t *
vls_session_get (vls_worker_t * wrk, u32 vls_index)
{
  if (pool_is_free_index (wrk->vls_pool, vls_index))
    return 0;
  return pool_elt_at_index (wrk->vls_pool, vls_index);
}

vcl_session_handle_t
vlsh_to_sh (vls_handle_t vlsh)
{
  vcl_locked_session_t *vls;
  int rv;

  vls = vls_get_w_dlock (vlsh);
  if (!vls)
    return INVALID_SESSION_ID;
  rv = vls_to_sh (vls);
  vls_dunlock (vls);
  return rv;
}

vcl_session_handle_t
vlsh_to_session_index (vls_handle_t vlsh)
{
  vcl_session_handle_t sh;
  sh = vlsh_to_sh (vlsh);
  return vppcom_session_index (sh);
}

vls_handle_t
vls_si_wi_to_vlsh (u32 session_index, u32 vcl_wrk_index)
{
  vls_worker_t *wrk = vls_worker_get_current ();
  uword *vlshp;
  vlshp = hash_get (wrk->session_handle_to_vlsh_table,
		    vcl_session_handle_from_wrk_session_index (session_index,
							       vcl_wrk_index));
  return vlshp ? *vlshp : VLS_INVALID_HANDLE;
}

vls_handle_t
vls_session_index_to_vlsh (uint32_t session_index)
{
  vls_handle_t vlsh;

  vls_mt_table_rlock ();
  vlsh = vls_si_wi_to_vlsh (session_index, vcl_get_worker_index ());
  vls_mt_table_runlock ();

  return vlsh;
}

u8
vls_is_shared_by_wrk (vcl_locked_session_t * vls, u32 wrk_index)
{
  vls_shared_data_t *vls_shd;
  int i;

  if (vls->shared_data_index == ~0)
    return 0;

  vls_shared_data_pool_rlock ();

  vls_shd = vls_shared_data_get (vls->shared_data_index);
  clib_spinlock_lock (&vls_shd->lock);

  for (i = 0; i < vec_len (vls_shd->workers_subscribed); i++)
    if (vls_shd->workers_subscribed[i] == wrk_index)
      {
	clib_spinlock_unlock (&vls_shd->lock);
	vls_shared_data_pool_runlock ();
	return 1;
      }
  clib_spinlock_unlock (&vls_shd->lock);

  vls_shared_data_pool_runlock ();
  return 0;
}

static void
vls_listener_wrk_set (vcl_locked_session_t * vls, u32 wrk_index, u8 is_active)
{
  vls_shared_data_t *vls_shd;

  if (vls->shared_data_index == ~0)
    {
      clib_warning ("not a shared session");
      return;
    }

  vls_shared_data_pool_rlock ();

  vls_shd = vls_shared_data_get (vls->shared_data_index);

  clib_spinlock_lock (&vls_shd->lock);
  clib_bitmap_set (vls_shd->listeners, wrk_index, is_active);
  clib_spinlock_unlock (&vls_shd->lock);

  vls_shared_data_pool_runlock ();
}

static u32
vls_shared_get_owner (vcl_locked_session_t * vls)
{
  vls_shared_data_t *vls_shd;
  u32 owner_wrk;

  vls_shared_data_pool_rlock ();

  vls_shd = vls_shared_data_get (vls->shared_data_index);
  owner_wrk = vls_shd->owner_wrk_index;

  vls_shared_data_pool_runlock ();

  return owner_wrk;
}

static u8
vls_listener_wrk_is_active (vcl_locked_session_t * vls, u32 wrk_index)
{
  vls_shared_data_t *vls_shd;
  u8 is_set;

  if (vls->shared_data_index == ~0)
    {
      clib_warning ("not a shared session");
      return 0;
    }

  vls_shared_data_pool_rlock ();

  vls_shd = vls_shared_data_get (vls->shared_data_index);

  clib_spinlock_lock (&vls_shd->lock);
  is_set = clib_bitmap_get (vls_shd->listeners, wrk_index);
  clib_spinlock_unlock (&vls_shd->lock);

  vls_shared_data_pool_runlock ();

  return (is_set == 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;
  vcl_send_session_unlisten (wrk, s);
  s->session_state = STATE_LISTEN_NO_MQ;
  vls_listener_wrk_set (vls, wrk_index, 0 /* is_active */ );
}

static int
vls_shared_data_subscriber_position (vls_shared_data_t * vls_shd,
				     u32 wrk_index)
{
  int i;

  for (i = 0; i < vec_len (vls_shd->workers_subscribed); i++)
    {
      if (vls_shd->workers_subscribed[i] == wrk_index)
	return i;
    }
  return -1;
}

int
vls_unshare_session (vcl_locked_session_t * vls, vcl_worker_t * wrk)
{
  vls_shared_data_t *vls_shd;
  int do_disconnect, pos;
  u32 n_subscribers;
  vcl_session_t *s;

  if (vls->shared_data_index == ~0)
    return 0;

  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 */ );

  vls_shared_data_pool_rlock ();

  vls_shd = vls_shared_data_get (vls->shared_data_index);
  clib_spinlock_lock (&vls_shd->lock);

  pos = vls_shared_data_subscriber_position (vls_shd, wrk->wrk_index);
  if (pos < 0)
    {
      clib_warning ("worker %u not subscribed for vls %u", wrk->wrk_index,
		    vls->worker_index);
      goto done;
    }

  /*
   * Unsubscribe from share data and fifos
   */
  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_shd->workers_subscribed, pos);

  /*
   * Cleanup vcl state
   */
  n_subscribers = vec_len (vls_shd->workers_subscribed);
  do_disconnect = s->session_state == STATE_LISTEN || !n_subscribers;
  vcl_session_cleanup (wrk, s, vcl_session_handle (s), do_disconnect);

  /*
   * No subscriber left, cleanup shared data
   */
  if (!n_subscribers)
    {
      u32 shd_index = vls_shared_data_index (vls_shd);

      clib_spinlock_unlock (&vls_shd->lock);
      vls_shared_data_pool_runlock ();

      vls_shared_data_free (shd_index);

      /* All locks have been dropped */
      return 0;
    }

  /* Return, if this is not the owning worker */
  if (vls_shd->owner_wrk_index != wrk->wrk_index)
    goto done;

  ASSERT (vec_len (vls_shd->workers_subscribed));

  /*
   *  Check if we can change owner or close
   */
  vls_shd->owner_wrk_index = vls_shd->workers_subscribed[0];
  vcl_send_session_worker_update (wrk, s, vls_shd->owner_wrk_index);

  /* XXX is this still needed? */
  if (vec_len (vls_shd->workers_subscribed) > 1)
    clib_warning ("more workers need to be updated");

done:

  clib_spinlock_unlock (&vls_shd->lock);
  vls_shared_data_pool_runlock ();

  return 0;
}

void
vls_init_share_session (vls_worker_t * vls_wrk, vcl_locked_session_t * vls)
{
  vls_shared_data_t *vls_shd;

  u32 vls_shd_index = vls_shared_data_alloc ();

  vls_shared_data_pool_rlock ();

  vls_shd = vls_shared_data_get (vls_shd_index);
  vls_shd->owner_wrk_index = vls_wrk->wrk_index;
  vls->shared_data_index = vls_shd_index;
  vec_add1 (vls_shd->workers_subscribed, vls_wrk->wrk_index);

  vls_shared_data_pool_runlock ();
}

void
vls_share_session (vls_worker_t * vls_wrk, vcl_locked_session_t * vls)
{
  vcl_worker_t *vcl_wrk = vcl_worker_get (vls_wrk->wrk_index);
  vls_shared_data_t *vls_shd;
  vcl_session_t *s;

  s = vcl_session_get (vcl_wrk, vls->session_index);
  if (!s)
    {
      clib_warning ("wrk %u session %u vls %u NOT AVAILABLE",
		    vcl_wrk->wrk_index, vls->session_index, vls->vls_index);
      return;
    }

  ASSERT (vls->shared_data_index != ~0);

  /* Reinit session lock */
  clib_spinlock_init (&vls->lock);

  vls_shared_data_pool_rlock ();

  vls_shd = vls_shared_data_get (vls->shared_data_index);

  clib_spinlock_lock (&vls_shd->lock);
  vec_add1 (vls_shd->workers_subscribed, vls_wrk->wrk_index);
  clib_spinlock_unlock (&vls_shd->lock);

  vls_shared_data_pool_runlock ();

  if (s->rx_fifo)
    {
      svm_fifo_add_subscriber (s->rx_fifo, vcl_wrk->vpp_wrk_index);
      svm_fifo_add_subscriber (s->tx_fifo, vcl_wrk->vpp_wrk_index);
    }
  else if (s->session_state == STATE_LISTEN)
    {
      s->session_state = STATE_LISTEN_NO_MQ;
    }
}

static void
vls_share_sessions (vls_worker_t * vls_parent_wrk, vls_worker_t * vls_wrk)
{
  vcl_locked_session_t *vls, *parent_vls;

  /* *INDENT-OFF* */
  pool_foreach (vls, vls_wrk->vls_pool, ({
    /* Initialize sharing on parent session */
    if (vls->shared_data_index == ~0)
      {
	parent_vls = vls_session_get (vls_parent_wrk, vls->vls_index);
	vls_init_share_session (vls_parent_wrk, parent_vls);
	vls->shared_data_index = parent_vls->shared_data_index;
      }
    vls_share_session (vls_wrk, vls);
  }));
  /* *INDENT-ON* */
}

void
vls_worker_copy_on_fork (vcl_worker_t * parent_wrk)
{
  vls_worker_t *vls_wrk = vls_worker_get_current (), *vls_parent_wrk;
  vcl_worker_t *wrk = vcl_worker_get_current ();
  u32 vls_index, session_index, wrk_index;
  vcl_session_handle_t sh;

  /*
   * init vcl worker
   */
  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);

  /*
   * init vls worker
   */
  vls_parent_wrk = vls_worker_get (parent_wrk->wrk_index);
  /* *INDENT-OFF* */
  hash_foreach (sh, vls_index, vls_parent_wrk->session_handle_to_vlsh_table,
    ({
      vcl_session_handle_parse (sh, &wrk_index, &session_index);
      hash_set (vls_wrk->session_handle_to_vlsh_table,
		vcl_session_handle_from_index (session_index), vls_index);
    }));
  /* *INDENT-ON* */
  vls_wrk->vls_pool = pool_dup (vls_parent_wrk->vls_pool);

  vls_share_sessions (vls_parent_wrk, vls_wrk);
}

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 ();
}

static inline u8
vls_mt_session_should_migrate (vcl_locked_session_t * vls)
{
  return (vls_mt_wrk_supported ()
	  && vls->worker_index != vcl_get_worker_index ());
}

static void
vls_mt_session_migrate (vcl_locked_session_t * vls)
{
  u32 wrk_index = vcl_get_worker_index ();
  vcl_worker_t *wrk;
  u32 src_sid, sid;
  vcl_session_t *session;
  uword *p;

  ASSERT (vls_mt_wrk_supported () && vls->worker_index != wrk_index);

  /*
   * VCL session on current vcl worker already allocated. Update current
   * owner worker and index and return
   */
  if ((p = hash_get (vls->vcl_wrk_index_to_session_index, wrk_index)))
    {
      vls->worker_index = wrk_index;
      vls->session_index = (u32) p[0];
      return;
    }

  /*
   * Ask vcl worker that owns the original vcl session to clone it into
   * current vcl worker session pool
   */

  if (!(p = hash_get (vls->vcl_wrk_index_to_session_index,
		      vls->owner_vcl_wrk_index)))
    {
      VERR ("session in owner worker(%u) is free", vls->owner_vcl_wrk_index);
      ASSERT (0);
      return;
    }

  src_sid = (u32) p[0];
  wrk = vcl_worker_get_current ();
  session = vcl_session_alloc (wrk);
  sid = session->session_index;
  vls_send_clone_and_share_rpc (wrk, vls, sid, vls_get_worker_index (),
				vls->owner_vcl_wrk_index, vls->vls_index,
				src_sid);
  session->session_index = sid;
  vls->worker_index = wrk_index;
  vls->session_index = sid;
  hash_set (vls->vcl_wrk_index_to_session_index, wrk_index, sid);
  VDBG (1, "migrate session of worker (session): %u (%u) -> %u (%u)",
	vls->owner_vcl_wrk_index, src_sid, wrk_index, sid);

  if (PREDICT_FALSE (session->is_vep && session->vep.next_sh != ~0))
    {
      /* TODO: rollback? */
      VERR ("can't migrate nonempty epoll session");
      ASSERT (0);
      return;
    }
  else if (PREDICT_FALSE (!session->is_vep &&
			  session->session_state != STATE_CLOSED))
    {
      /* TODO: rollback? */
      VERR ("migrate NOT supported, session_status (%u)",
	    session->session_state);
      ASSERT (0);
      return;
    }
}

static inline void
vls_mt_detect (void)
{
  if (PREDICT_FALSE (vcl_get_worker_index () == ~0))
    vls_mt_add ();
}

#define vls_mt_guard(_vls, _op)						\
  int _locks_acq = 0;							\
  if (vls_mt_wrk_supported ())						\
    {									\
      if (PREDICT_FALSE (_vls 						\
	    && ((vcl_locked_session_t *)_vls)->worker_index != 		\
		vcl_get_worker_index ()))				\
	  vls_mt_session_migrate (_vls);				\
    }									\
  else									\
    {									\
      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;

  vls_mt_detect ();
  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;

  vls_mt_detect ();
  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;

  vls_mt_detect ();
  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;

  vls_mt_detect ();
  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;

  vls_mt_detect ();
  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;

  vls_mt_detect ();
  if (!(vls = vls_get_w_dlock (vlsh)))
    return VPPCOM_EBADFD;
  if (vls_mt_session_should_migrate (vls))
    vls_mt_session_migrate (vls);
  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;

  vls_mt_detect ();
  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;

  vls_mt_detect ();
  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;

  vls_mt_detect ();
  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;
  u32 owner_wrk;

  if (vls_mt_wrk_supported ())
    return;

  s = vcl_session_get (wrk, vls->session_index);
  switch (s->session_state)
    {
    case STATE_LISTEN:
      if (is_add)
	{
	  vls_listener_wrk_set (vls, vls->worker_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. */
      owner_wrk = vls_shared_get_owner (vls);
      if (!vls_listener_wrk_is_active (vls, owner_wrk))
	vls_listener_wrk_stop_listen (vls, owner_wrk);
      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;

  vls_mt_detect ();
  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_detect ();
  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;
}

static void
vls_mt_session_cleanup (vcl_locked_session_t * vls)
{
  u32 session_index, wrk_index, current_vcl_wrk;
  vcl_worker_t *wrk = vcl_worker_get_current ();

  ASSERT (vls_mt_wrk_supported ());

  current_vcl_wrk = vcl_get_worker_index ();

  /* *INDENT-OFF* */
  hash_foreach (wrk_index, session_index, vls->vcl_wrk_index_to_session_index,
    ({
      if (current_vcl_wrk != wrk_index)
	vls_send_session_cleanup_rpc (wrk, wrk_index, session_index);
    }));
  /* *INDENT-ON* */
  hash_free (vls->vcl_wrk_index_to_session_index);
}

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

  vls_mt_detect ();
  vls_mt_table_wlock ();

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

  vls_mt_guard (vls, VLS_MT_OP_SPOOL);

  if (vls_is_shared (vls))
    rv = vls_unshare_session (vls, vcl_worker_get_current ());
  else
    rv = vppcom_session_close (vls_to_sh (vls));

  if (vls_mt_wrk_supported ())
    vls_mt_session_cleanup (vls);

  vls_free (vls);
  vls_mt_unguard ();

  vls_mt_table_wunlock ();

  return rv;
}

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

  vls_mt_detect ();

  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_mt_detect ();
  vls_mt_table_rlock ();
  ep_vls = vls_get_and_lock (ep_vlsh);
  vls = vls_get_and_lock (vlsh);

  if (vls_mt_session_should_migrate (ep_vls))
    vls_mt_session_migrate (ep_vls);

  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_mt_table_runlock ();

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

  vls_mt_table_rlock ();
  ep_vls = vls_get (ep_vlsh);
  vls = vls_get (vlsh);
  vls_unlock (vls);
  vls_unlock (ep_vls);
  vls_mt_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;

  vls_mt_detect ();
  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_detect ();
  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;

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

static void
vls_cleanup_vcl_worker (vcl_worker_t * wrk)
{
  vls_worker_t *vls_wrk = vls_worker_get (wrk->wrk_index);

  /* 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 */ );

  vls_worker_free (vls_wrk);
}

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 parent_wrk_index;

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

  /*
   * Clear old state
   */
  vcl_set_worker_index (~0);

  /*
   * Allocate and register vcl worker with vpp
   */
  if (vppcom_worker_register ())
    {
      VERR ("couldn't register new worker!");
      return;
    }

  /*
   * Allocate/initialize vls worker and share sessions
   */
  vls_worker_alloc ();
  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)
{
  vls_worker_t *wrk = vls_worker_get_current ();

  /* Unshare the sessions. VCL will clean up the worker */
  vls_unshare_vcl_worker_sessions (vcl_worker_get_current ());
  vls_worker_free (wrk);
}

static void
vls_clone_and_share_rpc_handler (void *args)
{
  vls_clone_and_share_msg_t *msg = (vls_clone_and_share_msg_t *) args;
  vls_worker_t *wrk = vls_worker_get_current (), *dst_wrk;
  vcl_locked_session_t *vls, *dst_vls;
  vcl_worker_t *vcl_wrk = vcl_worker_get_current (), *dst_vcl_wrk;
  vcl_session_t *s, *dst_s;

  vls = vls_session_get (wrk, msg->vls_index);

  if (!vls_mt_wrk_supported ())
    vls_init_share_session (wrk, vls);

  s = vcl_session_get (vcl_wrk, msg->session_index);
  dst_wrk = vls_worker_get (msg->origin_vls_wrk);
  dst_vcl_wrk = vcl_worker_get (msg->origin_vcl_wrk);
  dst_vls = vls_session_get (dst_wrk, msg->origin_vls_index);
  dst_vls->shared_data_index = vls->shared_data_index;
  dst_s = vcl_session_get (dst_vcl_wrk, msg->origin_session_index);
  clib_memcpy (dst_s, s, sizeof (*s));

  dst_vcl_wrk->rpc_done = 1;

  VDBG (1, "proces session clone of worker (session): %u (%u) -> %u (%u)",
	vcl_wrk->wrk_index, msg->session_index, dst_vcl_wrk->wrk_index,
	msg->origin_session_index);
}

static void
vls_session_cleanup_rpc_handler (void *args)
{
  vls_sess_cleanup_msg_t *msg = (vls_sess_cleanup_msg_t *) args;
  vcl_worker_t *wrk = vcl_worker_get_current ();
  vcl_worker_t *dst_wrk = vcl_worker_get (msg->origin_vcl_wrk);

  vppcom_session_close (vcl_session_handle_from_index (msg->session_index));

  dst_wrk->rpc_done = 1;

  VDBG (1, "proces session cleanup of worker (session): %u (%u) from %u ()",
	wrk->wrk_index, msg->session_index, dst_wrk->wrk_index);
}

static void
vls_rpc_handler (void *args)
{
  vls_rpc_msg_t *msg = (vls_rpc_msg_t *) args;
  switch (msg->type)
    {
    case VLS_RPC_CLONE_AND_SHARE:
      vls_clone_and_share_rpc_handler (msg->data);
      break;
    case VLS_RPC_SESS_CLEANUP:
      vls_session_cleanup_rpc_handler (msg->data);
      break;
    default:
      break;
    }
}

void
vls_send_clone_and_share_rpc (vcl_worker_t * wrk,
			      vcl_locked_session_t * vls, u32 session_index,
			      u32 vls_wrk_index, u32 dst_wrk_index,
			      u32 dst_vls_index, u32 dst_session_index)
{
  u8 data[sizeof (u8) + sizeof (vls_clone_and_share_msg_t)];
  vls_clone_and_share_msg_t *msg;
  vls_rpc_msg_t *rpc;
  int ret;

  rpc = (vls_rpc_msg_t *) & data;
  rpc->type = VLS_RPC_CLONE_AND_SHARE;
  msg = (vls_clone_and_share_msg_t *) & rpc->data;
  msg->origin_vls_wrk = vls_wrk_index;
  msg->origin_vls_index = vls->vls_index;
  msg->origin_vcl_wrk = wrk->wrk_index;
  msg->origin_session_index = session_index;
  msg->vls_index = dst_vls_index;
  msg->session_index = dst_session_index;

  wrk->rpc_done = 0;
  ret = vcl_send_worker_rpc (dst_wrk_index, rpc, sizeof (data));

  VDBG (1, "send session clone to wrk (session): %u (%u) -> %u (%u), ret=%d",
	dst_wrk_index, msg->session_index, msg->origin_vcl_wrk,
	msg->origin_session_index, ret);
  while (!ret && !wrk->rpc_done)
    ;
}

void
vls_send_session_cleanup_rpc (vcl_worker_t * wrk,
			      u32 dst_wrk_index, u32 dst_session_index)
{
  u8 data[sizeof (u8) + sizeof (vls_sess_cleanup_msg_t)];
  vls_sess_cleanup_msg_t *msg;
  vls_rpc_msg_t *rpc;
  int ret;

  rpc = (vls_rpc_msg_t *) & data;
  rpc->type = VLS_RPC_SESS_CLEANUP;
  msg = (vls_sess_cleanup_msg_t *) & rpc->data;
  msg->origin_vcl_wrk = wrk->wrk_index;
  msg->session_index = dst_session_index;

  wrk->rpc_done = 0;
  ret = vcl_send_worker_rpc (dst_wrk_index, rpc, sizeof (data));

  VDBG (1, "send session cleanup to wrk (session): %u (%u) from %u, ret=%d",
	dst_wrk_index, msg->session_index, msg->origin_vcl_wrk, ret);
  while (!ret && !wrk->rpc_done)
    ;
}

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);
  clib_rwlock_init (&vlsm->shared_data_lock);
  pool_alloc (vlsm->workers, vcm->cfg.max_workers);

  pthread_atfork (vls_app_pre_fork, vls_app_fork_parent_handler,
		  vls_app_fork_child_handler);
  atexit (vls_app_exit);
  vls_worker_alloc ();
  vlsl->vls_wrk_index = vcl_get_worker_index ();
  vls_mt_locks_init ();
  vcm->wrk_rpc_fn = vls_rpc_handler;
  return VPPCOM_OK;
}

unsigned char
vls_use_eventfd (void)
{
  return vcm->cfg.use_mq_eventfd;
}

unsigned char
vls_mt_wrk_supported (void)
{
  return vcm->cfg.mt_wrk_supported;
}

int
vls_use_real_epoll (void)
{
  if (vcl_get_worker_index () == ~0)
    return 0;

  return vcl_worker_get_current ()->vcl_needs_real_epoll;
}

void
vls_register_vcl_worker (void)
{
  if (vppcom_worker_register () != VPPCOM_OK)
    {
      VERR ("failed to register worker");
      return;
    }
}

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