/*
 * Copyright (c) 2005 by Internet Systems Consortium, Inc. ("ISC")
 * Copyright (c) 1997,1999 by 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.
 */


/* When this symbol is defined allocations via memget are made slightly
   bigger and some debugging info stuck before and after the region given
   back to the caller. */
/* #define DEBUGGING_MEMCLUSTER */
#define MEMCLUSTER_ATEND

#include "port_before.h"

#include <sys/types.h>
#include <sys/uio.h>
#include <sys/param.h>
#include <sys/stat.h>

#include <netinet/in.h>
#include <arpa/inet.h>
#include <arpa/nameser.h>

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

#include <isc/memcluster.h>
#include <isc/assertions.h>

#include "port_after.h"

#ifdef MEMCLUSTER_RECORD
#ifndef DEBUGGING_MEMCLUSTER
#define DEBUGGING_MEMCLUSTER
#endif
#endif

#define DEF_MAX_SIZE            1100
#define DEF_MEM_TARGET          4096

typedef u_int32_t fence_t;

typedef struct {
        void *                  next;
#if defined(DEBUGGING_MEMCLUSTER)
#if defined(MEMCLUSTER_RECORD)
        const char *            file;
        int                     line;
#endif
        size_t                  size;
        fence_t                 fencepost;
#endif
} memcluster_element;

#define SMALL_SIZE_LIMIT sizeof(memcluster_element)
#define P_SIZE sizeof(void *)
#define FRONT_FENCEPOST 0xfebafeba
#define BACK_FENCEPOST 0xabefabef
#define FENCEPOST_SIZE 4

#ifndef MEMCLUSTER_LITTLE_MALLOC
#define MEMCLUSTER_BIG_MALLOC 1
#define NUM_BASIC_BLOCKS 64
#endif

struct stats {
        u_long                  gets;
        u_long                  totalgets;
        u_long                  blocks;
        u_long                  freefrags;
};

#ifdef DO_PTHREADS
#include <pthread.h>
static pthread_mutex_t  memlock = PTHREAD_MUTEX_INITIALIZER;
#define MEMLOCK         (void)pthread_mutex_lock(&memlock)
#define MEMUNLOCK       (void)pthread_mutex_unlock(&memlock)
#else
/*
 * Catch bad lock usage in non threaded build.
 */
static unsigned int     memlock = 0;
#define MEMLOCK         do { INSIST(memlock == 0); memlock = 1; } while (0)
#define MEMUNLOCK       do { INSIST(memlock == 1); memlock = 0; } while (0)
#endif  /* DO_PTHEADS */

/* Private data. */

static size_t                   max_size;
static size_t                   mem_target;
#ifndef MEMCLUSTER_BIG_MALLOC
static size_t                   mem_target_half;
static size_t                   mem_target_fudge;
#endif
static memcluster_element **    freelists;
#ifdef MEMCLUSTER_RECORD
static memcluster_element **    activelists;
#endif
#ifdef MEMCLUSTER_BIG_MALLOC
static memcluster_element *     basic_blocks;
#endif
static struct stats *           stats;

/* Forward. */

static size_t                   quantize(size_t);
#if defined(DEBUGGING_MEMCLUSTER)
static void                     check(unsigned char *, int, size_t);
#endif

/* Public. */

int
meminit(size_t init_max_size, size_t target_size) {

#if defined(DEBUGGING_MEMCLUSTER)
        INSIST(sizeof(fence_t) == FENCEPOST_SIZE);
#endif
        if (freelists != NULL) {
                errno = EEXIST;
                return (-1);
        }
        if (init_max_size == 0U)
                max_size = DEF_MAX_SIZE;
        else
                max_size = init_max_size;
        if (target_size == 0U)
                mem_target = DEF_MEM_TARGET;
        else
                mem_target = target_size;
#ifndef MEMCLUSTER_BIG_MALLOC
        mem_target_half = mem_target / 2;
        mem_target_fudge = mem_target + mem_target / 4;
#endif
        freelists = malloc(max_size * sizeof (memcluster_element *));
        stats = malloc((max_size+1) * sizeof (struct stats));
        if (freelists == NULL || stats == NULL) {
                errno = ENOMEM;
                return (-1);
        }
        memset(freelists, 0,
               max_size * sizeof (memcluster_element *));
        memset(stats, 0, (max_size + 1) * sizeof (struct stats));
#ifdef MEMCLUSTER_RECORD
        activelists = malloc((max_size + 1) * sizeof (memcluster_element *));
        if (activelists == NULL) {
                errno = ENOMEM;
                return (-1);
        }
        memset(activelists, 0,
               (max_size + 1) * sizeof (memcluster_element *));
#endif
#ifdef MEMCLUSTER_BIG_MALLOC
        basic_blocks = NULL;
#endif
        return (0);
}

void *
__memget(size_t size) {
        return (__memget_record(size, NULL, 0));
}

void *
__memget_record(size_t size, const char *file, int line) {
        size_t new_size = quantize(size);
#if defined(DEBUGGING_MEMCLUSTER)
        memcluster_element *e;
        char *p;
        fence_t fp = BACK_FENCEPOST;
#endif
        void *ret;

        MEMLOCK;

#if !defined(MEMCLUSTER_RECORD)
        UNUSED(file);
        UNUSED(line);
#endif
        if (freelists == NULL) {
                if (meminit(0, 0) == -1) {
                        MEMUNLOCK;
                        return (NULL);
                }
        }
        if (size == 0U) {
                MEMUNLOCK;
                errno = EINVAL;
                return (NULL);
        }
        if (size >= max_size || new_size >= max_size) {
                /* memget() was called on something beyond our upper limit. */
                stats[max_size].gets++;
                stats[max_size].totalgets++;
#if defined(DEBUGGING_MEMCLUSTER)
                e = malloc(new_size);
                if (e == NULL) {
                        MEMUNLOCK;
                        errno = ENOMEM;
                        return (NULL);
                }
                e->next = NULL;
                e->size = size;
#ifdef MEMCLUSTER_RECORD
                e->file = file;
                e->line = line;
                e->next = activelists[max_size];
                activelists[max_size] = e;
#endif
                MEMUNLOCK;
                e->fencepost = FRONT_FENCEPOST;
                p = (char *)e + sizeof *e + size;
                memcpy(p, &fp, sizeof fp);
                return ((char *)e + sizeof *e);
#else
                MEMUNLOCK;
                return (malloc(size));
#endif
        }

        /*
         * 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 (freelists[new_size] == NULL) {
                int i, frags;
                size_t total_size;
                void *new;
                char *curr, *next;

#ifdef MEMCLUSTER_BIG_MALLOC
                if (basic_blocks == NULL) {
                        new = malloc(NUM_BASIC_BLOCKS * mem_target);
                        if (new == NULL) {
                                MEMUNLOCK;
                                errno = ENOMEM;
                                return (NULL);
                        }
                        curr = new;
                        next = curr + mem_target;
                        for (i = 0; i < (NUM_BASIC_BLOCKS - 1); i++) {
                                ((memcluster_element *)curr)->next = next;
                                curr = next;
                                next += mem_target;
                        }
                        /*
                         * curr is now pointing at the last block in the
                         * array.
                         */
                        ((memcluster_element *)curr)->next = NULL;
                        basic_blocks = new;
                }
                total_size = mem_target;
                new = basic_blocks;
                basic_blocks = basic_blocks->next;
#else
                if (new_size > mem_target_half)
                        total_size = mem_target_fudge;
                else
                        total_size = mem_target;
                new = malloc(total_size);
                if (new == NULL) {
                        MEMUNLOCK;
                        errno = ENOMEM;
                        return (NULL);
                }
#endif
                frags = total_size / new_size;
                stats[new_size].blocks++;
                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++) {
#if defined (DEBUGGING_MEMCLUSTER)
                        memset(curr, 0xa5, new_size);
#endif
                        ((memcluster_element *)curr)->next = next;
                        curr = next;
                        next += new_size;
                }
                /* curr is now pointing at the last block in the array. */
#if defined (DEBUGGING_MEMCLUSTER)
                memset(curr, 0xa5, new_size);
#endif
                ((memcluster_element *)curr)->next = freelists[new_size];
                freelists[new_size] = new;
        }

        /* The free list uses the "rounded-up" size "new_size". */
#if defined (DEBUGGING_MEMCLUSTER)
        e = freelists[new_size];
        ret = (char *)e + sizeof *e;
        /*
         * Check to see if this buffer has been written to while on free list.
         */
        check(ret, 0xa5, new_size - sizeof *e);
        /*
         * Mark memory we are returning.
         */
        memset(ret, 0xe5, size);
#else
        ret = freelists[new_size];
#endif
        freelists[new_size] = freelists[new_size]->next;
#if defined(DEBUGGING_MEMCLUSTER)
        e->next = NULL;
        e->size = size;
        e->fencepost = FRONT_FENCEPOST;
#ifdef MEMCLUSTER_RECORD
        e->file = file;
        e->line = line;
        e->next = activelists[size];
        activelists[size] = e;
#endif
        p = (char *)e + sizeof *e + size;
        memcpy(p, &fp, sizeof fp);
#endif

        /*
         * 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.
         */
        stats[size].gets++;
        stats[size].totalgets++;
        stats[new_size].freefrags--;
        MEMUNLOCK;
#if defined(DEBUGGING_MEMCLUSTER)
        return ((char *)e + sizeof *e);
#else
        return (ret);
#endif
}

/*%
 * This is a call from an external caller,
 * so we want to count this as a user "put".
 */
void
__memput(void *mem, size_t size) {
        __memput_record(mem, size, NULL, 0);
}

void
__memput_record(void *mem, size_t size, const char *file, int line) {
        size_t new_size = quantize(size);
#if defined (DEBUGGING_MEMCLUSTER)
        memcluster_element *e;
        memcluster_element *el;
#ifdef MEMCLUSTER_RECORD
        memcluster_element *prev;
#endif
        fence_t fp;
        char *p;
#endif

        MEMLOCK;

#if !defined (MEMCLUSTER_RECORD)
        UNUSED(file);
        UNUSED(line);
#endif

        REQUIRE(freelists != NULL);

        if (size == 0U) {
                MEMUNLOCK;
                errno = EINVAL;
                return;
        }

#if defined (DEBUGGING_MEMCLUSTER)
        e = (memcluster_element *) ((char *)mem - sizeof *e);
        INSIST(e->fencepost == FRONT_FENCEPOST);
        INSIST(e->size == size);
        p = (char *)e + sizeof *e + size;
        memcpy(&fp, p, sizeof fp);
        INSIST(fp == BACK_FENCEPOST);
        INSIST(((u_long)mem % 4) == 0);
#ifdef MEMCLUSTER_RECORD
        prev = NULL;
        if (size == max_size || new_size >= max_size)
                el = activelists[max_size];
        else
                el = activelists[size];
        while (el != NULL && el != e) {
                prev = el;
                el = el->next;
        }
        INSIST(el != NULL);     /*%< double free */
        if (prev == NULL) {
                if (size == max_size || new_size >= max_size)
                        activelists[max_size] = el->next;
                else
                        activelists[size] = el->next;
        } else
                prev->next = el->next;
#endif
#endif

        if (size == max_size || new_size >= max_size) {
                /* memput() called on something beyond our upper limit */
#if defined(DEBUGGING_MEMCLUSTER)
                free(e);
#else
                free(mem);
#endif

                INSIST(stats[max_size].gets != 0U);
                stats[max_size].gets--;
                MEMUNLOCK;
                return;
        }

        /* The free list uses the "rounded-up" size "new_size": */
#if defined(DEBUGGING_MEMCLUSTER)
        memset(mem, 0xa5, new_size - sizeof *e); /*%< catch write after free */
        e->size = 0;    /*%< catch double memput() */
#ifdef MEMCLUSTER_RECORD
        e->file = file;
        e->line = line;
#endif
#ifdef MEMCLUSTER_ATEND
        e->next = NULL;
        el = freelists[new_size];
        while (el != NULL && el->next != NULL)
                el = el->next;
        if (el)
                el->next = e;
        else
                freelists[new_size] = e;
#else
        e->next = freelists[new_size];
        freelists[new_size] = (void *)e;
#endif
#else
        ((memcluster_element *)mem)->next = freelists[new_size];
        freelists[new_size] = (memcluster_element *)mem;
#endif

        /*
         * 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(stats[size].gets != 0U);
        stats[size].gets--;
        stats[new_size].freefrags++;
        MEMUNLOCK;
}

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

/*%
 * Print the stats[] on the stream "out" with suitable formatting.
 */
void
memstats(FILE *out) {
        size_t i;
#ifdef MEMCLUSTER_RECORD
        memcluster_element *e;
#endif

        MEMLOCK;

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

                if (s->totalgets == 0U && s->gets == 0U)
                        continue;
                fprintf(out, "%s%5lu: %11lu gets, %11lu rem",
                        (i == max_size) ? ">=" : "  ",
                        (unsigned long)i, s->totalgets, s->gets);
                if (s->blocks != 0U)
                        fprintf(out, " (%lu bl, %lu ff)",
                                s->blocks, s->freefrags);
                fputc('\n', out);
        }
#ifdef MEMCLUSTER_RECORD
        fprintf(out, "Active Memory:\n");
        for (i = 1; i <= max_size; i++) {
                if ((e = activelists[i]) != NULL)
                        while (e != NULL) {
                                fprintf(out, "%s:%d %p:%lu\n",
                                        e->file != NULL ? e->file :
                                                "<UNKNOWN>", e->line,
                                        (char *)e + sizeof *e,
                                        (u_long)e->size);
                                e = e->next;
                        }
        }
#endif
        MEMUNLOCK;
}

int
memactive(void) {
        size_t i;

        if (stats == NULL)
                return (0);
        for (i = 1; i <= max_size; i++)
                if (stats[i].gets != 0U)
                        return (1);
        return (0);
}

/* Private. */

/*%
 * Round up size to a multiple of sizeof(void *).  This guarantees that a
 * block is at least sizeof void *, and that we won't violate alignment
 * restrictions, both of which are needed to make lists of blocks.
 */
static size_t
quantize(size_t size) {
        int remainder;
        /*
         * If there is no remainder for the integer division of
         *
         *      (rightsize/P_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_ aligned on P_SIZE boundaries.
         */
        remainder = size % P_SIZE;
        if (remainder != 0)
                size += P_SIZE - remainder;
#if defined(DEBUGGING_MEMCLUSTER)
        return (size + SMALL_SIZE_LIMIT + sizeof (int));
#else
        return (size);
#endif
}

#if defined(DEBUGGING_MEMCLUSTER)
static void
check(unsigned char *a, int value, size_t len) {
        size_t i;
        for (i = 0; i < len; i++)
                INSIST(a[i] == value);
}
#endif

/*! \file */