lib/isc/mem.c

	mem.c revision 1cef22510e8065b4cbd7584d38b6b6f4a2082f53
/*
 * Copyright (C) 1997, 1998  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 INTERNET SOFTWARE CONSORTIUM DISCLAIMS
 * ALL WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES
 * OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL INTERNET SOFTWARE
 * CONSORTIUM 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.
 */

#include <config.h>

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

#include <isc/assertions.h>
#include <isc/error.h>
#include <isc/mem.h>

#ifndef ISC_SINGLETHREADED
#include <isc/mutex.h>
#include "util.h"
#else
#define LOCK(ctx)
#define UNLOCK(ctx)
#endif

/*
 * Types.
 */

typedef struct {
    void *          next;
} element;

typedef struct {
    size_t          size;
    /*
     * This structure must be ALIGNMENT_SIZE bytes.
     */
} *size_info;

struct stats {
    unsigned long       gets;
    unsigned long       totalgets;
    unsigned long       blocks;
    unsigned long       freefrags;
};

#define MEM_MAGIC           0x4D656d43U /* MemC. */
#define VALID_CONTEXT(c)        ((c) != NULL && \
                     (c)->magic == MEM_MAGIC)

struct isc_memctx {
    unsigned int        magic;
    isc_mutex_t     lock;
    size_t          max_size;
    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;
    struct stats *      stats;
};

/* Forward. */

static size_t           quantize(size_t);

/* Constants. */

#define DEF_MAX_SIZE        1100
#define DEF_MEM_TARGET      4096
#define ALIGNMENT_SIZE      sizeof (void *)
#define NUM_BASIC_BLOCKS    64          /* must be > 1 */
#define TABLE_INCREMENT     1024

/* Private Inline-able. */

static inline size_t
quantize(size_t size) {
    int remainder;

    /*
     * If there is no remainder for the integer division of
     *
     *  (rightsize/ALIGNMENT_SIZE)
     *
     * then we already have a good size; if not, then we need
     * to round up the result in order to get a size big
     * enough to satisfy the request and be aligned on ALIGNMENT_SIZE
     * byte boundaries.
     */
    remainder = size % ALIGNMENT_SIZE;
    if (remainder != 0)
            size += ALIGNMENT_SIZE - remainder;
    return (size);
}

/* Public. */

isc_result_t
isc_memctx_create(size_t init_max_size, size_t target_size,
          isc_memctx_t *ctxp)
{
    isc_memctx_t ctx;

    REQUIRE(ctxp != NULL && *ctxp == NULL);

    ctx = malloc(sizeof *ctx);
    if (init_max_size == 0)
        ctx->max_size = DEF_MAX_SIZE;
    else
        ctx->max_size = init_max_size;
    if (target_size == 0)
        ctx->mem_target = DEF_MEM_TARGET;
    else
        ctx->mem_target = target_size;
    ctx->freelists = malloc(ctx->max_size * sizeof (element *));
    if (ctx->freelists == NULL) {
        free(ctx);
        return (ISC_R_NOMEMORY);
    }
    memset(ctx->freelists, 0,
           ctx->max_size * sizeof (element *));
    ctx->stats = malloc((ctx->max_size+1) * sizeof (struct stats));
    if (ctx->stats == NULL) {
        free(ctx->freelists);
        free(ctx);
        return (ISC_R_NOMEMORY);
    }
    memset(ctx->stats, 0, (ctx->max_size + 1) * sizeof (struct stats));
    ctx->basic_blocks = NULL;
    ctx->basic_table = NULL;
    ctx->basic_table_count = 0;
    ctx->basic_table_size = 0;
    ctx->lowest = NULL;
    ctx->highest = NULL;
    if (isc_mutex_init(&ctx->lock) != ISC_R_SUCCESS) {
        free(ctx->stats);
        free(ctx->freelists);
        free(ctx);
        UNEXPECTED_ERROR(__FILE__, __LINE__,
                 "isc_mutex_init() failed");
        return (ISC_R_UNEXPECTED);
    }
    ctx->magic = MEM_MAGIC;
    *ctxp = ctx;
    return (ISC_R_SUCCESS);
}

void
isc_memctx_destroy(isc_memctx_t *ctxp) {
    unsigned int i;
    isc_memctx_t ctx;

    REQUIRE(ctxp != NULL);
    ctx = *ctxp;
    REQUIRE(VALID_CONTEXT(ctx));

    ctx->magic = 0;

    for (i = 0; i <= ctx->max_size; i++)
        INSIST(ctx->stats[i].gets == 0);

    for (i = 0; i < ctx->basic_table_count; i++)
        free(ctx->basic_table[i]);
    free(ctx->freelists);
    free(ctx->stats);
    free(ctx->basic_table);
    (void)isc_mutex_destroy(&ctx->lock);
    free(ctx);

    *ctxp = NULL;
}

static void
more_basic_blocks(isc_memctx_t ctx) {
    void *new;
    unsigned char *curr, *next;
    unsigned char *first, *last;
    unsigned char **table;
    unsigned int table_size;
    int i;

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

    if (ctx->basic_table_count <= ctx->basic_table_size) {
        table_size = ctx->basic_table_size + TABLE_INCREMENT;
        table = malloc(table_size * sizeof (unsigned char *));
        if (table == NULL)
            return;
        memcpy(table, ctx->basic_table,
               ctx->basic_table_size * sizeof (unsigned char *));
        free(ctx->basic_table);
        ctx->basic_table = table;
        ctx->basic_table_size = table_size;
    } else
        table = NULL;

    new = malloc(NUM_BASIC_BLOCKS * ctx->mem_target);
    if (new == NULL) {
        if (table != NULL)
            free(table);
        return;
    }
    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 = 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;
}

void *
__isc_mem_get(isc_memctx_t ctx, size_t size) {
    size_t new_size = quantize(size);
    void *ret;

    REQUIRE(size > 0);
    REQUIRE(VALID_CONTEXT(ctx));
    LOCK(&ctx->lock);

    if (size >= ctx->max_size || new_size >= ctx->max_size) {
        /* memget() was called on something beyond our upper limit. */
        ret = malloc(size);
        if (ret != NULL) {
            ctx->stats[ctx->max_size].gets++;
            ctx->stats[ctx->max_size].totalgets++;
        }
        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) {
        int i, frags;
        size_t total_size;
        void *new;
        unsigned char *curr, *next;

        if (ctx->basic_blocks == NULL) {
            more_basic_blocks(ctx);
            if (ctx->basic_blocks == NULL) {
                ret = NULL;
                goto done;
            }
        }
        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;
        for (i = 0; i < (frags - 1); i++) {
            ((element *)curr)->next = next;
            curr = next;
            next += new_size;
        }
        /* curr is now pointing at the last block in the array. */
        ((element *)curr)->next = NULL;
        ctx->freelists[new_size] = new;
    }

    /* 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--;

 done:
    UNLOCK(&ctx->lock);

    return (ret);
}

/*
 * This is a call from an external caller,
 * so we want to count this as a user "put".
 */
void
__isc_mem_put(isc_memctx_t ctx, void *mem, size_t size) {
    size_t new_size = quantize(size);

    REQUIRE(size > 0);
    REQUIRE(VALID_CONTEXT(ctx));
    LOCK(&ctx->lock);

    if (size == ctx->max_size || new_size >= ctx->max_size) {
        /* memput() called on something beyond our upper limit */
        free(mem);
        INSIST(ctx->stats[ctx->max_size].gets != 0);
        ctx->stats[ctx->max_size].gets--;
        goto done;
    }

    /* 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++;

 done:
    UNLOCK(&ctx->lock);
}

void *
__isc_mem_getdebug(isc_memctx_t ctx, size_t size, const char *file, int line) {
    void *ptr;

    ptr = __isc_mem_get(ctx, size);
    fprintf(stderr, "%s:%d: mem_get(%p, %lu) -> %p\n", file, line,
        ctx, (unsigned long)size, ptr);
    return (ptr);
}

void
__isc_mem_putdebug(isc_memctx_t ctx, void *ptr, size_t size, const char *file,
           int line)
{
    fprintf(stderr, "%s:%d: mem_put(%p, %p, %lu)\n", file, line,
        ctx, ptr, (unsigned long)size);
    __isc_mem_put(ctx, ptr, size);
}

/*
 * Print the stats[] on the stream "out" with suitable formatting.
 */
void
isc_mem_stats(isc_memctx_t ctx, FILE *out) {
    size_t i;

    REQUIRE(VALID_CONTEXT(ctx));
    LOCK(&ctx->lock);

    if (ctx->freelists == NULL)
        return;
    for (i = 1; i <= ctx->max_size; i++) {
        const struct stats *s = &ctx->stats[i];

        if (s->totalgets == 0 && s->gets == 0)
            continue;
        fprintf(out, "%s%5d: %11lu gets, %11lu rem",
            (i == ctx->max_size) ? ">=" : "  ",
            i, s->totalgets, s->gets);
        if (s->blocks != 0)
            fprintf(out, " (%lu bl, %lu ff)",
                s->blocks, s->freefrags);
        fputc('\n', out);
    }

    UNLOCK(&ctx->lock);
}

isc_boolean_t
isc_mem_valid(isc_memctx_t ctx, void *ptr) {
    unsigned char *cp = ptr;
    isc_boolean_t result = ISC_FALSE;

    REQUIRE(VALID_CONTEXT(ctx));
    LOCK(&ctx->lock);

    if (ctx->lowest != NULL && cp >= ctx->lowest && cp <= ctx->highest)
        result = ISC_TRUE;

    UNLOCK(&ctx->lock);

    return (result);
}

/*
 * Replacements for malloc() and free().
 */

void *
isc_mem_allocate(isc_memctx_t ctx, size_t size) {
    size_info si;

    size += ALIGNMENT_SIZE;
    si = isc_mem_get(ctx, size);
    if (si == NULL)
        return (NULL);
    si->size = size;
    return (&si[1]);
}

void
isc_mem_free(isc_memctx_t ctx, void *ptr) {
    size_info si;

    si = &(((size_info)ptr)[-1]);
    isc_mem_put(ctx, si, si->size);
}

#ifdef ISC_MEMCLUSTER_LEGACY

/*
 * Public Legacy.
 */

static isc_memctx_t         default_context = NULL;

int
meminit(size_t init_max_size, size_t target_size) {
    /* need default_context lock here */
    if (default_context != NULL)
        return (-1);
    return (isc_mem_create(init_max_size, target_size, &default_context));
}

isc_memctx_t
mem_default_context(void) {
    /* need default_context lock here */
    if (default_context == NULL && meminit(0, 0) == -1)
        return (NULL);
    return (default_context);
}

void *
__memget(size_t size) {
    /* need default_context lock here */
    if (default_context == NULL && meminit(0, 0) == -1)
        return (NULL);
    return (__mem_get(default_context, size));
}

void
__memput(void *mem, size_t size) {
    /* need default_context lock here */
    REQUIRE(default_context != NULL);
    __mem_put(default_context, mem, size);
}

void *
__memget_debug(size_t size, const char *file, int line) {
    void *ptr;
    ptr = __memget(size);
    fprintf(stderr, "%s:%d: memget(%lu) -> %p\n", file, line,
        (unsigned long)size, ptr);
    return (ptr);
}

void
__memput_debug(void *ptr, size_t size, const char *file, int line) {
    fprintf(stderr, "%s:%d: memput(%p, %lu)\n", file, line,
        ptr, (unsigned long)size);
    __memput(ptr, size);
}

int
memvalid(void *ptr) {
    /* need default_context lock here */
    REQUIRE(default_context != NULL);
    return (mem_valid(default_context, ptr));
}

void
memstats(FILE *out) {
    /* need default_context lock here */
    REQUIRE(default_context != NULL);
    mem_stats(default_context, out);
}

#endif /* ISC_MEMCLUSTER_LEGACY */