/* * include/common/buffer.h * Buffer management definitions, macros and inline functions. * * Copyright (C) 2000-2012 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 _COMMON_BUFFER_H #define _COMMON_BUFFER_H #include #include #include #include #include #include #include #include #include #include /* an element of the list. It represents an object that need to * acquire a buffer to continue its process. */ struct buffer_wait { void *target; /* The waiting object that should be woken up */ int (*wakeup_cb)(void *); /* The function used to wake up the , passed as argument */ struct list list; /* Next element in the list */ }; extern struct pool_head *pool_head_buffer; extern struct list buffer_wq; __decl_hathreads(extern HA_SPINLOCK_T buffer_wq_lock); int init_buffer(); 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); } /**************************************************/ /* Functions below are used for buffer allocation */ /**************************************************/ /* Allocates a buffer and assigns it to *buf. If no memory is available, * ((char *)1) is assigned instead with a zero size. No control is made to * check if *buf already pointed to another buffer. The allocated buffer is * returned, or NULL in case no memory is available. */ static inline struct buffer *b_alloc(struct buffer *buf) { char *area; *buf = BUF_WANTED; area = pool_alloc_dirty(pool_head_buffer); if (unlikely(!area)) { activity[tid].buf_wait++; return NULL; } buf->area = area; buf->size = pool_head_buffer->size; return buf; } /* Allocates a buffer and assigns it to *buf. If no memory is available, * ((char *)1) is assigned instead with a zero size. No control is made to * check if *buf already pointed to another buffer. The allocated buffer is * returned, or NULL in case no memory is available. The difference with * b_alloc() is that this function only picks from the pool and never calls * malloc(), so it can fail even if some memory is available. */ static inline struct buffer *b_alloc_fast(struct buffer *buf) { char *area; *buf = BUF_WANTED; area = pool_get_first(pool_head_buffer); if (unlikely(!area)) return NULL; buf->area = area; buf->size = pool_head_buffer->size; return buf; } /* Releases buffer (no check of emptiness). The buffer's head is marked * empty. */ static inline void __b_free(struct buffer *buf) { char *area = buf->area; /* 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(); pool_free(pool_head_buffer, area); } /* Releases buffer if allocated, and marks it empty. */ static inline void b_free(struct buffer *buf) { if (buf->size) __b_free(buf); } /* Ensures that is allocated. If an allocation is needed, it ensures that * there are still at least buffers available in the pool after this * allocation so that we don't leave the pool in a condition where a session or * a response buffer could not be allocated anymore, resulting in a deadlock. * This means that we sometimes need to try to allocate extra entries even if * only one buffer is needed. * * We need to lock the pool here to be sure to have buffers available * after the allocation, regardless how many threads that doing it in the same * time. So, we use internal and lockless memory functions (prefixed with '__'). */ static inline struct buffer *b_alloc_margin(struct buffer *buf, int margin) { char *area; ssize_t idx; unsigned int cached; if (buf->size) return buf; cached = 0; idx = pool_get_index(pool_head_buffer); if (idx >= 0) cached = pool_cache[tid][idx].count; *buf = BUF_WANTED; #ifndef CONFIG_HAP_LOCKLESS_POOLS HA_SPIN_LOCK(POOL_LOCK, &pool_head_buffer->lock); #endif /* fast path */ if ((pool_head_buffer->allocated - pool_head_buffer->used + cached) > margin) { area = __pool_get_first(pool_head_buffer); if (likely(area)) { #ifndef CONFIG_HAP_LOCKLESS_POOLS HA_SPIN_UNLOCK(POOL_LOCK, &pool_head_buffer->lock); #endif goto done; } } /* slow path, uses malloc() */ area = __pool_refill_alloc(pool_head_buffer, margin); #ifndef CONFIG_HAP_LOCKLESS_POOLS HA_SPIN_UNLOCK(POOL_LOCK, &pool_head_buffer->lock); #endif if (unlikely(!area)) { activity[tid].buf_wait++; return NULL; } done: buf->area = area; buf->size = pool_head_buffer->size; return buf; } /* Offer a buffer currently belonging to target to whoever needs one. * Any pointer is valid for , 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. */ void __offer_buffer(void *from, unsigned int threshold); static inline void offer_buffers(void *from, unsigned int threshold) { if (LIST_ISEMPTY(&buffer_wq)) return; HA_SPIN_LOCK(BUF_WQ_LOCK, &buffer_wq_lock); if (!LIST_ISEMPTY(&buffer_wq)) __offer_buffer(from, threshold); HA_SPIN_UNLOCK(BUF_WQ_LOCK, &buffer_wq_lock); } #endif /* _COMMON_BUFFER_H */ /* * Local variables: * c-indent-level: 8 * c-basic-offset: 8 * End: */