src/memory.c

/*
 * Memory management functions.
 *
 * Copyright 2000-2007 Willy Tarreau <w@1wt.eu>
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License
 * as published by the Free Software Foundation; either version
 * 2 of the License, or (at your option) any later version.
 *
 */

#include <types/applet.h>
#include <types/cli.h>
#include <types/global.h>
#include <types/stats.h>

#include <common/config.h>
#include <common/debug.h>
#include <common/hathreads.h>
#include <common/memory.h>
#include <common/mini-clist.h>
#include <common/standard.h>

#include <proto/applet.h>
#include <proto/cli.h>
#include <proto/channel.h>
#include <proto/log.h>
#include <proto/stream_interface.h>
#include <proto/stats.h>

/* These are the most common pools, expected to be initialized first. These
 * ones are allocated from an array, allowing to map them to an index.
 */
struct pool_head pool_base_start[MAX_BASE_POOLS] = { };
unsigned int pool_base_count = 0;

THREAD_LOCAL struct pool_cache_head pool_cache[MAX_BASE_POOLS] = { };
THREAD_LOCAL struct list pool_lru_head = { };            /* oldest objects   */
THREAD_LOCAL size_t pool_cache_bytes = 0;                /* total cache size */
THREAD_LOCAL size_t pool_cache_count = 0;                /* #cache objects   */

static struct list pools = LIST_HEAD_INIT(pools);
int mem_poison_byte = -1;

/* Try to find an existing shared pool with the same characteristics and
 * returns it, otherwise creates this one. NULL is returned if no memory
 * is available for a new creation. Two flags are supported :
 *   - MEM_F_SHARED to indicate that the pool may be shared with other users
 *   - MEM_F_EXACT to indicate that the size must not be rounded up
 */
struct pool_head *create_pool(char *name, unsigned int size, unsigned int flags)
{
	struct pool_head *pool;
	struct pool_head *entry;
	struct list *start;
	unsigned int align;

	/* We need to store a (void *) at the end of the chunks. Since we know
	 * that the malloc() function will never return such a small size,
	 * let's round the size up to something slightly bigger, in order to
	 * ease merging of entries. Note that the rounding is a power of two.
	 * This extra (void *) is not accounted for in the size computation
	 * so that the visible parts outside are not affected.
	 *
	 * Note: for the LRU cache, we need to store 2 doubly-linked lists.
	 */

	if (!(flags & MEM_F_EXACT)) {
		align = 4 * sizeof(void *); // 2 lists = 4 pointers min
		size  = ((size + POOL_EXTRA + align - 1) & -align) - POOL_EXTRA;
	}

	/* TODO: thread: we do not lock pool list for now because all pools are
	 * created during HAProxy startup (so before threads creation) */
	start = &pools;
	pool = NULL;

	list_for_each_entry(entry, &pools, list) {
		if (entry->size == size) {
			/* either we can share this place and we take it, or
			 * we look for a sharable one or for the next position
			 * before which we will insert a new one.
			 */
			if (flags & entry->flags & MEM_F_SHARED) {
				/* we can share this one */
				pool = entry;
				DPRINTF(stderr, "Sharing %s with %s\n", name, pool->name);
				break;
			}
		}
		else if (entry->size > size) {
			/* insert before this one */
			start = &entry->list;
			break;
		}
	}

	if (!pool) {
		if (pool_base_count < MAX_BASE_POOLS)
			pool = &pool_base_start[pool_base_count++];

		if (!pool) {
			/* look for a freed entry */
			for (entry = pool_base_start; entry != pool_base_start + MAX_BASE_POOLS; entry++) {
				if (!entry->size) {
					pool = entry;
					break;
				}
			}
		}

		if (!pool)
			pool = calloc(1, sizeof(*pool));

		if (!pool)
			return NULL;
		if (name)
			strlcpy2(pool->name, name, sizeof(pool->name));
		pool->size = size;
		pool->flags = flags;
		LIST_ADDQ(start, &pool->list);
	}
	pool->users++;
#ifndef CONFIG_HAP_LOCKLESS_POOLS
	HA_SPIN_INIT(&pool->lock);
#endif
	return pool;
}

#ifdef CONFIG_HAP_LOCKLESS_POOLS
/* Allocates new entries for pool <pool> until there are at least <avail> + 1
 * available, then returns the last one for immediate use, so that at least
 * <avail> are left available in the pool upon return. NULL is returned if the
 * last entry could not be allocated. It's important to note that at least one
 * allocation is always performed even if there are enough entries in the pool.
 * A call to the garbage collector is performed at most once in case malloc()
 * returns an error, before returning NULL.
 */
void *__pool_refill_alloc(struct pool_head *pool, unsigned int avail)
{
	void *ptr = NULL, **free_list;
	int failed = 0;
	int size = pool->size;
	int limit = pool->limit;
	int allocated = pool->allocated, allocated_orig = allocated;

	/* stop point */
	avail += pool->used;

	while (1) {
		if (limit && allocated >= limit) {
			HA_ATOMIC_ADD(&pool->allocated, allocated - allocated_orig);
			return NULL;
		}

		ptr = malloc(size + POOL_EXTRA);
		if (!ptr) {
			HA_ATOMIC_ADD(&pool->failed, 1);
			if (failed)
				return NULL;
			failed++;
			pool_gc(pool);
			continue;
		}
		if (++allocated > avail)
			break;

		free_list = pool->free_list;
		do {
			*POOL_LINK(pool, ptr) = free_list;
			__ha_barrier_store();
		} while (HA_ATOMIC_CAS(&pool->free_list, &free_list, ptr) == 0);
	}

	HA_ATOMIC_ADD(&pool->allocated, allocated - allocated_orig);
	HA_ATOMIC_ADD(&pool->used, 1);

#ifdef DEBUG_MEMORY_POOLS
	/* keep track of where the element was allocated from */
	*POOL_LINK(pool, ptr) = (void *)pool;
#endif
	return ptr;
}
void *pool_refill_alloc(struct pool_head *pool, unsigned int avail)
{
	void *ptr;

	ptr = __pool_refill_alloc(pool, avail);
	return ptr;
}
/*
 * This function frees whatever can be freed in pool <pool>.
 */
void pool_flush(struct pool_head *pool)
{
	void **next, *temp;
	int removed = 0;

	if (!pool)
		return;
	do {
		next = pool->free_list;
	} while (!HA_ATOMIC_CAS(&pool->free_list, &next, NULL));
	while (next) {
		temp = next;
		next = *POOL_LINK(pool, temp);
		removed++;
		free(temp);
	}
	pool->free_list = next;
	HA_ATOMIC_SUB(&pool->allocated, removed);
	/* here, we should have pool->allocate == pool->used */
}

/*
 * This function frees whatever can be freed in all pools, but respecting
 * the minimum thresholds imposed by owners. It takes care of avoiding
 * recursion because it may be called from a signal handler.
 *
 * <pool_ctx> is unused
 */
void pool_gc(struct pool_head *pool_ctx)
{
	static int recurse;
	int cur_recurse = 0;
	struct pool_head *entry;

	if (recurse || !HA_ATOMIC_CAS(&recurse, &cur_recurse, 1))
		return;

	list_for_each_entry(entry, &pools, list) {
		while ((int)((volatile int)entry->allocated - (volatile int)entry->used) > (int)entry->minavail) {
			struct pool_free_list cmp, new;

			cmp.seq = entry->seq;
			__ha_barrier_load();
			cmp.free_list = entry->free_list;
			__ha_barrier_load();
			if (cmp.free_list == NULL)
				break;
			new.free_list = *POOL_LINK(entry, cmp.free_list);
			new.seq = cmp.seq + 1;
			if (__ha_cas_dw(&entry->free_list, &cmp, &new) == 0)
				continue;
			free(cmp.free_list);
			HA_ATOMIC_SUB(&entry->allocated, 1);
		}
	}

	HA_ATOMIC_STORE(&recurse, 0);
}

/* frees an object to the local cache, possibly pushing oldest objects to the
 * global pool. Must not be called directly.
 */
void __pool_put_to_cache(struct pool_head *pool, void *ptr, ssize_t idx)
{
	struct pool_cache_item *item = (struct pool_cache_item *)ptr;
	struct pool_cache_head *ph = &pool_cache[idx];

	/* never allocated or empty */
	if (unlikely(ph->list.n == NULL)) {
		LIST_INIT(&ph->list);
		ph->size = pool->size;
		if (pool_lru_head.n == NULL)
			LIST_INIT(&pool_lru_head);
	}

	LIST_ADD(&ph->list, &item->by_pool);
	LIST_ADD(&pool_lru_head, &item->by_lru);
	ph->count++;
	pool_cache_count++;
	pool_cache_bytes += ph->size;

	if (pool_cache_bytes <= CONFIG_HAP_POOL_CACHE_SIZE)
		return;

	do {
		item = LIST_PREV(&pool_lru_head, struct pool_cache_item *, by_lru);
		/* note: by definition we remove oldest objects so they also are the
		 * oldest in their own pools, thus their next is the pool's head.
		 */
		ph = LIST_NEXT(&item->by_pool, struct pool_cache_head *, list);
		LIST_DEL(&item->by_pool);
		LIST_DEL(&item->by_lru);
		ph->count--;
		pool_cache_count--;
		pool_cache_bytes -= ph->size;
		__pool_free(pool_base_start + (ph - pool_cache), item);
	} while (pool_cache_bytes > CONFIG_HAP_POOL_CACHE_SIZE * 7 / 8);
}

#else /* CONFIG_HAP_LOCKLESS_POOLS */

/* Allocates new entries for pool <pool> until there are at least <avail> + 1
 * available, then returns the last one for immediate use, so that at least
 * <avail> are left available in the pool upon return. NULL is returned if the
 * last entry could not be allocated. It's important to note that at least one
 * allocation is always performed even if there are enough entries in the pool.
 * A call to the garbage collector is performed at most once in case malloc()
 * returns an error, before returning NULL.
 */
void *__pool_refill_alloc(struct pool_head *pool, unsigned int avail)
{
	void *ptr = NULL;
	int failed = 0;

	/* stop point */
	avail += pool->used;

	while (1) {
		if (pool->limit && pool->allocated >= pool->limit)
			return NULL;

		ptr = pool_alloc_area(pool->size + POOL_EXTRA);
		if (!ptr) {
			pool->failed++;
			if (failed)
				return NULL;
			failed++;
			pool_gc(pool);
			continue;
		}
		if (++pool->allocated > avail)
			break;

		*POOL_LINK(pool, ptr) = (void *)pool->free_list;
		pool->free_list = ptr;
	}
	pool->used++;
#ifdef DEBUG_MEMORY_POOLS
	/* keep track of where the element was allocated from */
	*POOL_LINK(pool, ptr) = (void *)pool;
#endif
	return ptr;
}
void *pool_refill_alloc(struct pool_head *pool, unsigned int avail)
{
	void *ptr;

	HA_SPIN_LOCK(POOL_LOCK, &pool->lock);
	ptr = __pool_refill_alloc(pool, avail);
	HA_SPIN_UNLOCK(POOL_LOCK, &pool->lock);
	return ptr;
}
/*
 * This function frees whatever can be freed in pool <pool>.
 */
void pool_flush(struct pool_head *pool)
{
	void *temp, *next;
	if (!pool)
		return;

	HA_SPIN_LOCK(POOL_LOCK, &pool->lock);
	next = pool->free_list;
	while (next) {
		temp = next;
		next = *POOL_LINK(pool, temp);
		pool->allocated--;
		pool_free_area(temp, pool->size + POOL_EXTRA);
	}
	pool->free_list = next;
	HA_SPIN_UNLOCK(POOL_LOCK, &pool->lock);
	/* here, we should have pool->allocate == pool->used */
}

/*
 * This function frees whatever can be freed in all pools, but respecting
 * the minimum thresholds imposed by owners. It takes care of avoiding
 * recursion because it may be called from a signal handler.
 *
 * <pool_ctx> is used when pool_gc is called to release resources to allocate
 * an element in __pool_refill_alloc. It is important because <pool_ctx> is
 * already locked, so we need to skip the lock here.
 */
void pool_gc(struct pool_head *pool_ctx)
{
	static int recurse;
	int cur_recurse = 0;
	struct pool_head *entry;

	if (recurse || !HA_ATOMIC_CAS(&recurse, &cur_recurse, 1))
		return;

	list_for_each_entry(entry, &pools, list) {
		void *temp, *next;
		//qfprintf(stderr, "Flushing pool %s\n", entry->name);
		if (entry != pool_ctx)
			HA_SPIN_LOCK(POOL_LOCK, &entry->lock);
		next = entry->free_list;
		while (next &&
		       (int)(entry->allocated - entry->used) > (int)entry->minavail) {
			temp = next;
			next = *POOL_LINK(entry, temp);
			entry->allocated--;
			pool_free_area(temp, entry->size + POOL_EXTRA);
		}
		entry->free_list = next;
		if (entry != pool_ctx)
			HA_SPIN_UNLOCK(POOL_LOCK, &entry->lock);
	}

	HA_ATOMIC_STORE(&recurse, 0);
}
#endif

/*
 * This function destroys a pool by freeing it completely, unless it's still
 * in use. This should be called only under extreme circumstances. It always
 * returns NULL if the resulting pool is empty, easing the clearing of the old
 * pointer, otherwise it returns the pool.
 * .
 */
void *pool_destroy(struct pool_head *pool)
{
	if (pool) {
		pool_flush(pool);
		if (pool->used)
			return pool;
		pool->users--;
		if (!pool->users) {
			LIST_DEL(&pool->list);
#ifndef CONFIG_HAP_LOCKLESS_POOLS
			HA_SPIN_DESTROY(&pool->lock);
#endif
			if ((pool - pool_base_start) < MAX_BASE_POOLS)
				memset(pool, 0, sizeof(*pool));
			else
				free(pool);
		}
	}
	return NULL;
}

/* This function dumps memory usage information into the trash buffer. */
void dump_pools_to_trash()
{
	struct pool_head *entry;
	unsigned long allocated, used;
	int nbpools;

	allocated = used = nbpools = 0;
	chunk_printf(&trash, "Dumping pools usage. Use SIGQUIT to flush them.\n");
	list_for_each_entry(entry, &pools, list) {
#ifndef CONFIG_HAP_LOCKLESS_POOLS
		HA_SPIN_LOCK(POOL_LOCK, &entry->lock);
#endif
		chunk_appendf(&trash, "  - Pool %s (%d bytes) : %d allocated (%u bytes), %d used, %d failures, %d users, @%p=%02d%s\n",
			 entry->name, entry->size, entry->allocated,
		         entry->size * entry->allocated, entry->used, entry->failed,
			 entry->users, entry, (int)pool_get_index(entry),
			 (entry->flags & MEM_F_SHARED) ? " [SHARED]" : "");

		allocated += entry->allocated * entry->size;
		used += entry->used * entry->size;
		nbpools++;
#ifndef CONFIG_HAP_LOCKLESS_POOLS
		HA_SPIN_UNLOCK(POOL_LOCK, &entry->lock);
#endif
	}
	chunk_appendf(&trash, "Total: %d pools, %lu bytes allocated, %lu used.\n",
		 nbpools, allocated, used);
}

/* Dump statistics on pools usage. */
void dump_pools(void)
{
	dump_pools_to_trash();
	qfprintf(stderr, "%s", trash.area);
}

/* This function returns the total number of failed pool allocations */
int pool_total_failures()
{
	struct pool_head *entry;
	int failed = 0;

	list_for_each_entry(entry, &pools, list)
		failed += entry->failed;
	return failed;
}

/* This function returns the total amount of memory allocated in pools (in bytes) */
unsigned long pool_total_allocated()
{
	struct pool_head *entry;
	unsigned long allocated = 0;

	list_for_each_entry(entry, &pools, list)
		allocated += entry->allocated * entry->size;
	return allocated;
}

/* This function returns the total amount of memory used in pools (in bytes) */
unsigned long pool_total_used()
{
	struct pool_head *entry;
	unsigned long used = 0;

	list_for_each_entry(entry, &pools, list)
		used += entry->used * entry->size;
	return used;
}

/* This function dumps memory usage information onto the stream interface's
 * read buffer. It returns 0 as long as it does not complete, non-zero upon
 * completion. No state is used.
 */
static int cli_io_handler_dump_pools(struct appctx *appctx)
{
	struct stream_interface *si = appctx->owner;

	dump_pools_to_trash();
	if (ci_putchk(si_ic(si), &trash) == -1) {
		si_cant_put(si);
		return 0;
	}
	return 1;
}

/* register cli keywords */
static struct cli_kw_list cli_kws = {{ },{
	{ { "show", "pools",  NULL }, "show pools     : report information about the memory pools usage", NULL, cli_io_handler_dump_pools },
	{{},}
}};

__attribute__((constructor))
static void __memory_init(void)
{
	cli_register_kw(&cli_kws);
}

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