/src/haproxy/include/haproxy/dynbuf.h

Source
/*
 * include/haproxy/dynbuf.h
 * Buffer management functions.
 *
 * Copyright (C) 2000-2020 Willy Tarreau - w@1wt.eu
 *
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation, version 2.1
 * exclusively.
 *
 * This library is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with this library; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
 */

#ifndef _HAPROXY_DYNBUF_H
#define _HAPROXY_DYNBUF_H

#include <stdio.h>
#include <stdlib.h>
#include <string.h>

#include <import/ist.h>
#include <haproxy/activity.h>
#include <haproxy/api.h>
#include <haproxy/buf.h>
#include <haproxy/chunk.h>
#include <haproxy/dynbuf-t.h>
#include <haproxy/global.h>
#include <haproxy/pool.h>

extern struct pool_head *pool_head_buffer;
extern struct pool_head *pool_head_large_buffer;
extern struct pool_head *pool_head_small_buffer;

int init_buffer(void);
void buffer_dump(FILE *o, struct buffer *b, int from, int to);

/*****************************************************************/
/* These functions are used to compute various buffer area sizes */
/*****************************************************************/

/* Return 1 if the buffer has less than 1/4 of its capacity free, otherwise 0 */
static inline int buffer_almost_full(const struct buffer *buf)
{
  if (b_is_null(buf))
    return 0;

  return b_almost_full(buf);
}

/* Return 1 if <sz> is the  default buffer size */
static inline int b_is_default_sz(size_t sz)
{
  return (sz == pool_head_buffer->size);
}

/* Return 1 if <sz> is the size of a large buffer (alwoys false is large buffers are not configured) */
static inline int b_is_large_sz(size_t sz)
{
  return (pool_head_large_buffer && sz == pool_head_large_buffer->size);
}

/* Return 1 if <sz> is the size of a small buffer */
static inline int b_is_small_sz(size_t sz)
{
  return (pool_head_small_buffer && sz == pool_head_small_buffer->size);
}

/* Return 1 if <bug> is a  default buffer */
static inline int b_is_default(struct buffer *buf)
{
  return b_is_default_sz(b_size(buf));
}

/* Return 1 if <buf> is a large buffer (alwoys 0 is large buffers are not configured) */
static inline int b_is_large(struct buffer *buf)
{
  return b_is_large_sz(b_size(buf));
}

/* Return 1 if <buf> is a small buffer */
static inline int b_is_small(struct buffer *buf)
{
  return b_is_small_sz(b_size(buf));
}

/**************************************************/
/* Functions below are used for buffer allocation */
/**************************************************/

/* returns non-zero if one may try to allocate a buffer for criticality flags
 * <crit> (made of a criticality and optional flags).
 */
static inline int b_may_alloc_for_crit(uint crit)
{
  int q = DB_CRIT_TO_QUEUE(crit & DB_F_CRIT_MASK);

  /* if this queue or any more critical ones have entries, we must wait */
  if (!(crit & DB_F_NOQUEUE) && th_ctx->bufq_map & ((2 << q) - 1))
    return 0;

  /* If the emergency buffers are too low, we won't try to allocate a
   * buffer either so that we speed up their release. As a corrolary, it
   * means that we're always allowed to try to fall back to an emergency
   * buffer if pool_alloc() fails. The minimum number of available
   * emergency buffers for an allocation depends on the queue:
   *  q == 0 -> 0%
   *  q == 1 -> 33%
   *  q == 2 -> 66%
   *  q == 3 -> 100%
   */
  if (th_ctx->emergency_bufs_left * 3 < q * global.tune.reserved_bufs)
    return 0;
  return 1;
}

/* Allocates one of the emergency buffers or returns NULL if there are none left */
static inline char *__b_get_emergency_buf(void)
{
  char *ret;

  if (!th_ctx->emergency_bufs_left)
    return NULL;

  th_ctx->emergency_bufs_left--;
  ret = th_ctx->emergency_bufs[th_ctx->emergency_bufs_left];
  th_ctx->emergency_bufs[th_ctx->emergency_bufs_left] = NULL;
  return ret;
}

/* Ensures that <buf> is allocated, or allocates it. If no memory is available,
 * ((char *)1) is assigned instead with a zero size. The allocated buffer is
 * returned, or NULL in case no memory is available. Since buffers only contain
 * user data, poisonning is always disabled as it brings no benefit and impacts
 * performance. Due to the difficult buffer_wait management, they are not
 * subject to forced allocation failures either. If other waiters are present
 * at higher criticality levels, we refrain from allocating.
 */
#define b_alloc(_buf, _crit)            \
({                  \
  char *_area = NULL;           \
  struct buffer *_retbuf = _buf;          \
  uint _criticality = _crit;         \
                  \
  if (!_retbuf->size) {           \
    *_retbuf = BUF_WANTED;         \
    if (b_may_alloc_for_crit(_criticality)) {   \
      _area = pool_alloc_flag(pool_head_buffer, POOL_F_NO_POISON | POOL_F_NO_FAIL); \
      if (unlikely(!_area))       \
        _area = __b_get_emergency_buf(); \
    }             \
    if (unlikely(!_area)) {         \
      activity[tid].buf_wait++;     \
      _retbuf = NULL;         \
    }              \
    else {             \
      _retbuf->area = _area;        \
      _retbuf->size = pool_head_buffer->size;   \
    }              \
  }               \
  _retbuf;              \
 })

/* Releases buffer <buf> (no check of emptiness). The buffer's head is marked
 * empty.
 */
#define __b_free(_buf)              \
  do {               \
    char *area = (_buf)->area;        \
    size_t sz = (_buf)->size;       \
                  \
    /* let's first clear the area to save an occasional "show sess all" \
     * glancing over our shoulder from getting a dangling pointer.      \
     */                         \
    *(_buf) = BUF_NULL;         \
    __ha_barrier_store();         \
    /* if enabled, large buffers are always strictly greater \
     * than the default buffers */        \
    if (unlikely(b_is_large_sz(sz)))      \
      pool_free(pool_head_large_buffer, area); \
    else if (unlikely(b_is_small_sz(sz)))      \
      pool_free(pool_head_small_buffer, area); \
    else if (th_ctx->emergency_bufs_left < global.tune.reserved_bufs) \
      th_ctx->emergency_bufs[th_ctx->emergency_bufs_left++] = area; \
    else              \
      pool_free(pool_head_buffer, area);   \
  } while (0)              \

/* Releases buffer <buf> if allocated, and marks it empty. */
#define b_free(_buf)        \
  do {         \
    if ((_buf)->size)   \
      __b_free((_buf)); \
  } while (0)


static inline struct buffer *b_alloc_small(struct buffer *buf)
{
  char *area = NULL;

  if (!buf->size) {
    area = pool_alloc(pool_head_small_buffer);
    if (!area)
      return NULL;
    buf->area = area;
    buf->size = global.tune.bufsize_small;
  }
  return buf;
}

static inline struct buffer *b_alloc_large(struct buffer *buf)
{
  char *area = NULL;

  if (!buf->size) {
    area = pool_alloc(pool_head_large_buffer);
    if (!area)
      return NULL;
    buf->area = area;
    buf->size = global.tune.bufsize_large;
  }
  return buf;
}

/* Offer one or multiple buffer currently belonging to target <from> to whoever
 * needs one. Any pointer is valid for <from>, including NULL. Its purpose is
 * to avoid passing a buffer to oneself in case of failed allocations (e.g.
 * need two buffers, get one, fail, release it and wake up self again). In case
 * of normal buffer release where it is expected that the caller is not waiting
 * for a buffer, NULL is fine. It will wake waiters on the current thread only.
 */
void __offer_buffers(void *from, unsigned int count);

static inline void offer_buffers(void *from, unsigned int count)
{
  int q;

  if (likely(!th_ctx->bufq_map))
    return;

  for (q = 0; q < DYNBUF_NBQ; q++) {
    if (!(th_ctx->bufq_map & (1 << q)))
      continue;

    BUG_ON_HOT(LIST_ISEMPTY(&th_ctx->buffer_wq[q]));
    __offer_buffers(from, count);
    break;
  }
}

/* Queues a buffer request for the current thread via <bw>, and returns
 * non-zero if the criticality allows to queue a request, otherwise returns
 * zero. If the <bw> was already queued, non-zero is returned so that the call
 * is idempotent. It is assumed that the buffer_wait struct had already been
 * preset with its context and callback, otherwise please use b_queue()
 * instead.
 */
static inline int b_requeue(enum dynbuf_crit crit, struct buffer_wait *bw)
{
  int q = DB_CRIT_TO_QUEUE(crit);

  if (LIST_INLIST(&bw->list))
    return 1;

  /* these ones are never queued */
  if (crit < DB_MUX_RX)
    return 0;

  th_ctx->bufq_map |= 1 << q;
  LIST_APPEND(&th_ctx->buffer_wq[q], &bw->list);
  return 1;
}

/* Queues a buffer request for the current thread via <bw> with the given <ctx>
 * and <cb>, and returns non-zero if the criticality allows to queue a request,
 * otherwise returns zero. If the <bw> was already queued, non-zero is returned
 * so that the call is idempotent.  If the buffer_wait struct had already been
 * preset with the ctx and cb, please use the lighter b_requeue() instead.
 */
static inline int b_queue(enum dynbuf_crit crit, struct buffer_wait *bw, void *ctx, int (*cb)(void *))
{
  bw->target    = ctx;
  bw->wakeup_cb = cb;
  return b_requeue(crit, bw);
}

/* Dequeues bw element <bw> from its list at for thread <thr> and updates the
 * thread's bufq_map if it was the last element. The element is assumed to be
 * in a list (it's the caller's job to test it). This is only meant to really
 * be used either by the owner thread or under thread isolation. You should
 * use b_dequeue() instead.
 */
static inline void _b_dequeue(struct buffer_wait *bw, int thr)
{
  struct thread_ctx *ctx = &ha_thread_ctx[thr];
  uint q;

  /* trick: detect if we're the last one and pointing to a root, so we
   * can figure the queue number since the root belongs to an array.
   */
  if (LIST_ATMOST1(&bw->list)) {
    /* OK then which root? */
    q = bw->list.n - &ctx->buffer_wq[0];
    BUG_ON_HOT(q >= DYNBUF_NBQ);
    ctx->bufq_map &= ~(1 << q);
  }
  LIST_DEL_INIT(&bw->list);
}

/* Dequeues bw element <bw> from its list and updates the bufq_map if if was
 * the last element. All users of buffer_wait should use this to dequeue (e.g.
 * when killing a pending request on timeout) so as to make sure that we keep
 * consistency between the list heads and the bitmap.
 */
static inline void b_dequeue(struct buffer_wait *bw)
{
  if (unlikely(LIST_INLIST(&bw->list)))
    _b_dequeue(bw, tid);
}

#endif /* _HAPROXY_DYNBUF_H */

/*
 * Local variables:
 *  c-indent-level: 8
 *  c-basic-offset: 8
 * End:
 */

Coverage Report

Created: 2026-04-03 06:23

Line	Count	Source
1		/*
2		* include/haproxy/dynbuf.h
3		* Buffer management functions.
4		*
5		* Copyright (C) 2000-2020 Willy Tarreau - w@1wt.eu
6		*
7		* This library is free software; you can redistribute it and/or
8		* modify it under the terms of the GNU Lesser General Public
9		* License as published by the Free Software Foundation, version 2.1
10		* exclusively.
11		*
12		* This library is distributed in the hope that it will be useful,
13		* but WITHOUT ANY WARRANTY; without even the implied warranty of
14		* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
15		* Lesser General Public License for more details.
16		*
17		* You should have received a copy of the GNU Lesser General Public
18		* License along with this library; if not, write to the Free Software
19		* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
20		*/
21
22		#ifndef _HAPROXY_DYNBUF_H
23		#define _HAPROXY_DYNBUF_H
24
25		#include <stdio.h>
26		#include <stdlib.h>
27		#include <string.h>
28
29		#include <import/ist.h>
30		#include <haproxy/activity.h>
31		#include <haproxy/api.h>
32		#include <haproxy/buf.h>
33		#include <haproxy/chunk.h>
34		#include <haproxy/dynbuf-t.h>
35		#include <haproxy/global.h>
36		#include <haproxy/pool.h>
37
38		extern struct pool_head *pool_head_buffer;
39		extern struct pool_head *pool_head_large_buffer;