mem.c

bind 9.3结合mysql数据库

/*
 * Copyright (C) 2004  Internet Systems Consortium, Inc. ("ISC")
 * Copyright (C) 1997-2003  Internet Software Consortium.
 *
 * Permission to use, copy, modify, and distribute this software for any
 * purpose with or without fee is hereby granted, provided that the above
 * copyright notice and this permission notice appear in all copies.
 *
 * THE SOFTWARE IS PROVIDED "AS IS" AND ISC DISCLAIMS ALL WARRANTIES WITH
 * REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY
 * AND FITNESS.  IN NO EVENT SHALL ISC BE LIABLE FOR ANY SPECIAL, DIRECT,
 * INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM
 * LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE
 * OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR
 * PERFORMANCE OF THIS SOFTWARE.
 */

/* $Id: mem.c,v 1.98.2.7.2.5 2004/03/16 05:50:24 marka Exp $ */

#include <config.h>

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

#include <limits.h>

#include <isc/magic.h>
#include <isc/mem.h>
#include <isc/msgs.h>
#include <isc/ondestroy.h>
#include <isc/string.h>

#include <isc/mutex.h>
#include <isc/util.h>

#ifndef ISC_MEM_DEBUGGING
#define ISC_MEM_DEBUGGING 0
#endif
LIBISC_EXTERNAL_DATA unsigned int isc_mem_debugging = ISC_MEM_DEBUGGING;

/*
 * Define ISC_MEM_USE_INTERNAL_MALLOC=1 to use the internal malloc()
 * implementation in preference to the system one.  The internal malloc()
 * is very space-efficient, and quite fast on uniprocessor systems.  It
 * performs poorly on multiprocessor machines.
 */
#ifndef ISC_MEM_USE_INTERNAL_MALLOC
#define ISC_MEM_USE_INTERNAL_MALLOC 0
#endif

/*
 * Constants.
 */

#define DEF_MAX_SIZE		1100
#define DEF_MEM_TARGET		4096
#define ALIGNMENT_SIZE		8		/* must be a power of 2 */
#define NUM_BASIC_BLOCKS	64		/* must be > 1 */
#define TABLE_INCREMENT		1024
#define DEBUGLIST_COUNT		1024

/*
 * Types.
 */
#if ISC_MEM_TRACKLINES
typedef struct debuglink debuglink_t;
struct debuglink {
	ISC_LINK(debuglink_t)	link;
	const void	       *ptr[DEBUGLIST_COUNT];
	unsigned int		size[DEBUGLIST_COUNT];
	const char	       *file[DEBUGLIST_COUNT];
	unsigned int		line[DEBUGLIST_COUNT];
	unsigned int		count;
};

#define FLARG_PASS	, file, line
#define FLARG		, const char *file, int line
#else
#define FLARG_PASS
#define FLARG
#endif

typedef struct element element;
struct element {
	element *		next;
};

typedef struct {
	/*
	 * This structure must be ALIGNMENT_SIZE bytes.
	 */
	union {
		size_t		size;
		char		bytes[ALIGNMENT_SIZE];
	} u;
} size_info;

struct stats {
	unsigned long		gets;
	unsigned long		totalgets;
#if ISC_MEM_USE_INTERNAL_MALLOC
	unsigned long		blocks;
	unsigned long		freefrags;
#endif /* ISC_MEM_USE_INTERNAL_MALLOC */
};

#define MEM_MAGIC		ISC_MAGIC('M', 'e', 'm', 'C')
#define VALID_CONTEXT(c)	ISC_MAGIC_VALID(c, MEM_MAGIC)

#if ISC_MEM_TRACKLINES
typedef ISC_LIST(debuglink_t)	debuglist_t;
#endif

struct isc_mem {
	unsigned int		magic;
	isc_ondestroy_t		ondestroy;
	isc_mutex_t		lock;
	isc_memalloc_t		memalloc;
	isc_memfree_t		memfree;
	void *			arg;
	size_t			max_size;
	isc_boolean_t		checkfree;
	struct stats *		stats;
	unsigned int		references;
	size_t			quota;
	size_t			total;
	size_t			inuse;
	size_t			maxinuse;
	size_t			hi_water;
	size_t			lo_water;
	isc_boolean_t		hi_called;
	isc_mem_water_t		water;
	void *			water_arg;
	ISC_LIST(isc_mempool_t)	pools;

#if ISC_MEM_USE_INTERNAL_MALLOC
	size_t			mem_target;
	element **		freelists;
	element *		basic_blocks;
	unsigned char **	basic_table;
	unsigned int		basic_table_count;
	unsigned int		basic_table_size;
	unsigned char *		lowest;
	unsigned char *		highest;
#endif /* ISC_MEM_USE_INTERNAL_MALLOC */

#if ISC_MEM_TRACKLINES
	debuglist_t *	 	debuglist;
#endif

	unsigned int		memalloc_failures;
};

#define MEMPOOL_MAGIC		ISC_MAGIC('M', 'E', 'M', 'p')
#define VALID_MEMPOOL(c)	ISC_MAGIC_VALID(c, MEMPOOL_MAGIC)

struct isc_mempool {
	/* always unlocked */
	unsigned int	magic;		/* magic number */
	isc_mutex_t    *lock;		/* optional lock */
	isc_mem_t      *mctx;		/* our memory context */
	/* locked via the memory context's lock */
	ISC_LINK(isc_mempool_t)	link;	/* next pool in this mem context */
	/* optionally locked from here down */
	element	       *items;		/* low water item list */
	size_t		size;		/* size of each item on this pool */
	unsigned int	maxalloc;	/* max number of items allowed */
	unsigned int	allocated;	/* # of items currently given out */
	unsigned int	freecount;	/* # of items on reserved list */
	unsigned int	freemax;	/* # of items allowed on free list */
	unsigned int	fillcount;	/* # of items to fetch on each fill */
	/* Stats only. */
	unsigned int	gets;		/* # of requests to this pool */
	/* Debugging only. */
#if ISC_MEMPOOL_NAMES
	char		name[16];	/* printed name in stats reports */
#endif
};

/*
 * Private Inline-able.
 */

#if ! ISC_MEM_TRACKLINES
#define ADD_TRACE(a, b, c, d, e)
#define DELETE_TRACE(a, b, c, d, e)
#else
#define ADD_TRACE(a, b, c, d, e) \
	do { \
		if ((isc_mem_debugging & (ISC_MEM_DEBUGTRACE | \
					  ISC_MEM_DEBUGRECORD)) != 0 && \
		     b != NULL) \
		         add_trace_entry(a, b, c, d, e); \
	} while (0)
#define DELETE_TRACE(a, b, c, d, e)	delete_trace_entry(a, b, c, d, e)

static void
print_active(isc_mem_t *ctx, FILE *out);

/*
 * mctx must be locked.
 */
static inline void
add_trace_entry(isc_mem_t *mctx, const void *ptr, unsigned int size
		FLARG)
{
	debuglink_t *dl;
	unsigned int i;

	if ((isc_mem_debugging & ISC_MEM_DEBUGTRACE) != 0)
		fprintf(stderr, isc_msgcat_get(isc_msgcat, ISC_MSGSET_MEM,
					       ISC_MSG_ADDTRACE,
					       "add %p size %u "
					       "file %s line %u mctx %p\n"),
			ptr, size, file, line, mctx);

	if (mctx->debuglist == NULL)
		return;

	if (size > mctx->max_size)
		size = mctx->max_size;

	dl = ISC_LIST_HEAD(mctx->debuglist[size]);
	while (dl != NULL) {
		if (dl->count == DEBUGLIST_COUNT)
			goto next;
		for (i = 0; i < DEBUGLIST_COUNT; i++) {
			if (dl->ptr[i] == NULL) {
				dl->ptr[i] = ptr;
				dl->size[i] = size;
				dl->file[i] = file;
				dl->line[i] = line;
				dl->count++;
				return;
			}
		}
	next:
		dl = ISC_LIST_NEXT(dl, link);
	}

	dl = malloc(sizeof(debuglink_t));
	INSIST(dl != NULL);

	ISC_LINK_INIT(dl, link);
	for (i = 1; i < DEBUGLIST_COUNT; i++) {
		dl->ptr[i] = NULL;
		dl->size[i] = 0;
		dl->file[i] = NULL;
		dl->line[i] = 0;
	}

	dl->ptr[0] = ptr;
	dl->size[0] = size;
	dl->file[0] = file;
	dl->line[0] = line;
	dl->count = 1;

	ISC_LIST_PREPEND(mctx->debuglist[size], dl, link);
}

static inline void
delete_trace_entry(isc_mem_t *mctx, const void *ptr, unsigned int size,
		   const char *file, unsigned int line)
{
	debuglink_t *dl;
	unsigned int i;

	if ((isc_mem_debugging & ISC_MEM_DEBUGTRACE) != 0)
		fprintf(stderr, isc_msgcat_get(isc_msgcat, ISC_MSGSET_MEM,
					       ISC_MSG_DELTRACE,
					       "del %p size %u "
					       "file %s line %u mctx %p\n"),
			ptr, size, file, line, mctx);

	if (mctx->debuglist == NULL)
		return;

	if (size > mctx->max_size)
		size = mctx->max_size;

	dl = ISC_LIST_HEAD(mctx->debuglist[size]);
	while (dl != NULL) {
		for (i = 0; i < DEBUGLIST_COUNT; i++) {
			if (dl->ptr[i] == ptr) {
				dl->ptr[i] = NULL;
				dl->size[i] = 0;
				dl->file[i] = NULL;
				dl->line[i] = 0;

				INSIST(dl->count > 0);
				dl->count--;
				if (dl->count == 0) {
					ISC_LIST_UNLINK(mctx->debuglist[size],
							dl, link);
					free(dl);
				}
				return;
			}
		}
		dl = ISC_LIST_NEXT(dl, link);
	}

	/*
	 * If we get here, we didn't find the item on the list.  We're
	 * screwed.
	 */
	INSIST(dl != NULL);
}
#endif /* ISC_MEM_TRACKLINES */

#if ISC_MEM_USE_INTERNAL_MALLOC
static inline size_t
rmsize(size_t size) {
	/*
 	 * round down to ALIGNMENT_SIZE
	 */
	return (size & (~(ALIGNMENT_SIZE - 1)));
}

static inline size_t
quantize(size_t size) {
	/*
	 * Round up the result in order to get a size big
	 * enough to satisfy the request and be aligned on ALIGNMENT_SIZE
	 * byte boundaries.
	 */

	if (size == 0)
		return (ALIGNMENT_SIZE);
	return ((size + ALIGNMENT_SIZE - 1) & (~(ALIGNMENT_SIZE - 1)));
}

static inline isc_boolean_t
more_basic_blocks(isc_mem_t *ctx) {
	void *new;
	unsigned char *curr, *next;
	unsigned char *first, *last;
	unsigned char **table;
	unsigned int table_size;
	size_t increment;
	int i;

	/* Require: we hold the context lock. */

	/*
	 * Did we hit the quota for this context?
	 */
	increment = NUM_BASIC_BLOCKS * ctx->mem_target;
	if (ctx->quota != 0 && ctx->total + increment > ctx->quota)
		return (ISC_FALSE);

	INSIST(ctx->basic_table_count <= ctx->basic_table_size);
	if (ctx->basic_table_count == ctx->basic_table_size) {
		table_size = ctx->basic_table_size + TABLE_INCREMENT;
		table = (ctx->memalloc)(ctx->arg,
					table_size * sizeof(unsigned char *));
		if (table == NULL) {
			ctx->memalloc_failures++;
			return (ISC_FALSE);
		}
		if (ctx->basic_table_size != 0) {
			memcpy(table, ctx->basic_table,
			       ctx->basic_table_size *
			       sizeof(unsigned char *));
			(ctx->memfree)(ctx->arg, ctx->basic_table);
		}
		ctx->basic_table = table;
		ctx->basic_table_size = table_size;
	}

	new = (ctx->memalloc)(ctx->arg, NUM_BASIC_BLOCKS * ctx->mem_target);
	if (new == NULL) {
		ctx->memalloc_failures++;
		return (ISC_FALSE);
	}
	ctx->total += increment;
	ctx->basic_table[ctx->basic_table_count] = new;
	ctx->basic_table_count++;

	curr = new;
	next = curr + ctx->mem_target;
	for (i = 0; i < (NUM_BASIC_BLOCKS - 1); i++) {
		((element *)curr)->next = (element *)next;
		curr = next;
		next += ctx->mem_target;
	}
	/*
	 * curr is now pointing at the last block in the
	 * array.
	 */
	((element *)curr)->next = NULL;
	first = new;
	last = first + NUM_BASIC_BLOCKS * ctx->mem_target - 1;
	if (first < ctx->lowest || ctx->lowest == NULL)
		ctx->lowest = first;
	if (last > ctx->highest)
		ctx->highest = last;
	ctx->basic_blocks = new;

	return (ISC_TRUE);
}

static inline isc_boolean_t
more_frags(isc_mem_t *ctx, size_t new_size) {
	int i, frags;
	size_t total_size;
	void *new;
	unsigned char *curr, *next;

	/*
	 * Try to get more fragments by chopping up a basic block.
	 */

	if (ctx->basic_blocks == NULL) {
		if (!more_basic_blocks(ctx)) {
			/*
			 * We can't get more memory from the OS, or we've
			 * hit the quota for this context.
			 */
			/*
			 * XXXRTH  "At quota" notification here.
			 */
			return (ISC_FALSE);
		}
	}

	total_size = ctx->mem_target;
	new = ctx->basic_blocks;
	ctx->basic_blocks = ctx->basic_blocks->next;
	frags = total_size / new_size;
	ctx->stats[new_size].blocks++;
	ctx->stats[new_size].freefrags += frags;
	/*
	 * Set up a linked-list of blocks of size
	 * "new_size".
	 */
	curr = new;
	next = curr + new_size;
	total_size -= new_size;
	for (i = 0; i < (frags - 1); i++) {
		((element *)curr)->next = (element *)next;
		curr = next;
		next += new_size;
		total_size -= new_size;
	}
	/*
	 * Add the remaining fragment of the basic block to a free list.
	 */
	total_size = rmsize(total_size);
	if (total_size > 0) {
		((element *)next)->next = ctx->freelists[total_size];
		ctx->freelists[total_size] = (element *)next;
		ctx->stats[total_size].freefrags++;
	}
	/*
	 * curr is now pointing at the last block in the
	 * array.
	 */
	((element *)curr)->next = NULL;
	ctx->freelists[new_size] = new;

	return (ISC_TRUE);
}

static inline void *
mem_getunlocked(isc_mem_t *ctx, size_t size) {
	size_t new_size = quantize(size);
	void *ret;

	if (size >= ctx->max_size || new_size >= ctx->max_size) {
		/*
		 * memget() was called on something beyond our upper limit.
		 */
		if (ctx->quota != 0 && ctx->total + size > ctx->quota) {
			ret = NULL;
			goto done;
		}
		ret = (ctx->memalloc)(ctx->arg, size);
		if (ret == NULL) {
			ctx->memalloc_failures++;
			goto done;
		}
		ctx->total += size;
		ctx->inuse += size;
		ctx->stats[ctx->max_size].gets++;
		ctx->stats[ctx->max_size].totalgets++;
		/*
		 * If we don't set new_size to size, then the
		 * ISC_MEM_FILL code might write over bytes we
		 * don't own.
		 */
		new_size = size;
		goto done;
	}

	/*
	 * If there are no blocks in the free list for this size, get a chunk
	 * of memory and then break it up into "new_size"-sized blocks, adding
	 * them to the free list.
	 */
	if (ctx->freelists[new_size] == NULL && !more_frags(ctx, new_size))
		return (NULL);

	/*
	 * The free list uses the "rounded-up" size "new_size".
	 */
	ret = ctx->freelists[new_size];
	ctx->freelists[new_size] = ctx->freelists[new_size]->next;

	/*
	 * The stats[] uses the _actual_ "size" requested by the
	 * caller, with the caveat (in the code above) that "size" >= the
	 * max. size (max_size) ends up getting recorded as a call to
	 * max_size.
	 */
	ctx->stats[size].gets++;
	ctx->stats[size].totalgets++;
	ctx->stats[new_size].freefrags--;
	ctx->inuse += new_size;

 done:

#if ISC_MEM_FILL
	if (ret != NULL)
		memset(ret, 0xbe, new_size); /* Mnemonic for "beef". */
#endif

	return (ret);
}

#if ISC_MEM_FILL && ISC_MEM_CHECKOVERRUN
static inline void
check_overrun(void *mem, size_t size, size_t new_size) {
	unsigned char *cp;

	cp = (unsigned char *)mem;
	cp += size;
	while (size < new_size) {
		INSIST(*cp == 0xbe);
		cp++;
		size++;
	}
}
#endif

static inline void
mem_putunlocked(isc_mem_t *ctx, void *mem, size_t size) {
	size_t new_size = quantize(size);

	if (size == ctx->max_size || new_size >= ctx->max_size) {
		/*
		 * memput() called on something beyond our upper limit.
		 */
#if ISC_MEM_FILL
		memset(mem, 0xde, size); /* Mnemonic for "dead". */
#endif
		(ctx->memfree)(ctx->arg, mem);
		INSIST(ctx->stats[ctx->max_size].gets != 0);
		ctx->stats[ctx->max_size].gets--;
		INSIST(size <= ctx->total);
		ctx->inuse -= size;
		ctx->total -= size;
		return;
	}

#if ISC_MEM_FILL
#if ISC_MEM_CHECKOVERRUN
	check_overrun(mem, size, new_size);
#endif
	memset(mem, 0xde, new_size); /* Mnemonic for "dead". */
#endif

	/*
	 * The free list uses the "rounded-up" size "new_size".
	 */
	((element *)mem)->next = ctx->freelists[new_size];
	ctx->freelists[new_size] = (element *)mem;

	/*
	 * The stats[] uses the _actual_ "size" requested by the
	 * caller, with the caveat (in the code above) that "size" >= the
	 * max. size (max_size) ends up getting recorded as a call to
	 * max_size.
	 */
	INSIST(ctx->stats[size].gets != 0);
	ctx->stats[size].gets--;
	ctx->stats[new_size].freefrags++;
	ctx->inuse -= new_size;
}

#else /* ISC_MEM_USE_INTERNAL_MALLOC */