modules/mem/sharedmem_util.c

/* Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You under the Apache License, Version 2.0
 * (the "License"); you may not use this file except in compliance with
 * the License.  You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

/* Memory handler for a shared memory divided in slot.
 * This one uses shared memory.
 */
#define CORE_PRIVATE

#include "apr.h"
#include "apr_strings.h"
#include "apr_pools.h"
#include "apr_shm.h"

#include "httpd.h"
#include "http_config.h"
#include "http_log.h"

#include "slotmem.h"
#include "sharedmem_util.h"

/* The description of the slots to reuse the slotmem */
struct sharedslotdesc {
    apr_size_t item_size;
    int item_num;
};

struct ap_slotmem {
    char *name;
    apr_shm_t *shm;
    void *base;
    apr_size_t size;
    int num;
    apr_pool_t *globalpool;
    struct ap_slotmem *next;
};

/* global pool and list of slotmem we are handling */
static struct ap_slotmem *globallistmem = NULL;
static apr_pool_t *globalpool = NULL;

/*
 * Persiste the slotmem in a file
 * slotmem name and file name.
 * anonymous : $server_root/logs/anonymous.slotmem
 * :module.c : $server_root/logs/module.c.slotmem
 * abs_name  : $abs_name.slotmem
 *
 */
static const char *store_filename(apr_pool_t *pool, const char *slotmemname)
{
    const char *storename;
    const char *fname;
    if (strcmp(slotmemname, "anonymous") == 0)
        fname = ap_server_root_relative(pool, "logs/anonymous");
    else if (slotmemname[0] == ':') {
        const char *tmpname;
        tmpname = apr_pstrcat(pool, "logs/", &slotmemname[1], NULL);
        fname = ap_server_root_relative(pool, tmpname);
        }
    else
        fname = slotmemname;
    storename = apr_pstrcat(pool, fname , ".slotmem", NULL); 
    return storename;
}
static void store_slotmem(ap_slotmem_t *slotmem)
{
    apr_file_t *fp;
    apr_status_t rv;
    apr_size_t nbytes;
    const char *storename;

    storename = store_filename(slotmem->globalpool, slotmem->name);

    rv = apr_file_open(&fp, storename,  APR_CREATE | APR_READ | APR_WRITE, APR_OS_DEFAULT, slotmem->globalpool);
    if (APR_STATUS_IS_EEXIST(rv)) {
        apr_file_remove(storename, slotmem->globalpool);
        rv = apr_file_open(&fp, storename,  APR_CREATE | APR_READ | APR_WRITE, APR_OS_DEFAULT, slotmem->globalpool);
    }
    if (rv != APR_SUCCESS) {
        return;
    }
    nbytes = slotmem->size * slotmem->num;
    apr_file_write(fp, slotmem->base, &nbytes);
    apr_file_close(fp);
}
void restore_slotmem(void *ptr, const char *name, apr_size_t item_size, int item_num, apr_pool_t *pool)
{
    const char *storename;
    apr_file_t *fp;
    apr_size_t nbytes = item_size * item_num;
    apr_status_t rv;

    storename = store_filename(pool, name);
    rv = apr_file_open(&fp, storename,  APR_READ | APR_WRITE, APR_OS_DEFAULT, pool);
    if (rv == APR_SUCCESS) {
        apr_finfo_t fi;
        if (apr_file_info_get(&fi, APR_FINFO_SIZE, fp) == APR_SUCCESS) {
            if (fi.size == nbytes) {
                apr_file_read(fp, ptr, &nbytes);
            } else {
                apr_file_close(fp);
                apr_file_remove(storename, pool);
                return;
            }
        }
        apr_file_close(fp);
    }
}

apr_status_t cleanup_slotmem(void *param)
{
    ap_slotmem_t **mem = param;
    apr_status_t rv;
    apr_pool_t *pool = NULL;

    if (*mem) {
        ap_slotmem_t *next = *mem;
        pool = next->globalpool;
        while (next) {
            store_slotmem(next);
            rv = apr_shm_destroy(next->shm);
            next = next->next;
        }
        apr_pool_destroy(pool);        
    }
    return APR_SUCCESS;
}

static apr_status_t ap_slotmem_do(ap_slotmem_t *mem, ap_slotmem_callback_fn_t *func, void *data, apr_pool_t *pool)
{
    int i;
    void *ptr;

    if (!mem)
        return APR_ENOSHMAVAIL;

    ptr = mem->base;
    for (i = 0; i < mem->num; i++) {
        ptr = ptr + mem->size;
        func((void *)ptr, data, pool);
    }
    return 0;
}
static apr_status_t ap_slotmem_create(ap_slotmem_t **new, const char *name, apr_size_t item_size, int item_num, apr_pool_t *pool)
{
    void *slotmem = NULL;
    void *ptr;
    struct sharedslotdesc desc;
    ap_slotmem_t *res;
    ap_slotmem_t *next = globallistmem;
    const char *fname;
    apr_status_t rv;

    if (globalpool == NULL)
        return APR_ENOSHMAVAIL;
    if (name) {
        if (name[0] == ':')
            fname = name;
        else
            fname = ap_server_root_relative(pool, name);

        /* first try to attach to existing slotmem */
        if (next) {
            for (;;) {
                if (strcmp(next->name, fname) == 0) {
                    /* we already have it */
                    *new = next;
                    return APR_SUCCESS;
                }
                if (!next->next)
                    break;
                next = next->next;
            }
        }
    } else
        fname = "anonymous";

    /* first try to attach to existing shared memory */
    res = (ap_slotmem_t *) apr_pcalloc(globalpool, sizeof(ap_slotmem_t));
    if (name && name[0] != ':')
        rv = apr_shm_attach(&res->shm, fname, globalpool);
    else
        rv = APR_EINVAL;
    if (rv == APR_SUCCESS) {
        /* check size */
        if (apr_shm_size_get(res->shm) != item_size * item_num + sizeof(struct sharedslotdesc)) {
            apr_shm_detach(res->shm);
            res->shm = NULL;
            return APR_EINVAL;
        }
        ptr = apr_shm_baseaddr_get(res->shm);
        memcpy(&desc, ptr, sizeof(desc));
        if ( desc.item_size != item_size || desc.item_num != item_num) {
            apr_shm_detach(res->shm);
            res->shm = NULL;
            return APR_EINVAL;
        }
        ptr = ptr +  sizeof(desc);
    } else  {
        if (name && name[0] != ':') {
            apr_shm_remove(fname, globalpool);
            rv = apr_shm_create(&res->shm, item_size * item_num + sizeof(struct sharedslotdesc), fname, globalpool);
        } else {
            rv = apr_shm_create(&res->shm, item_size * item_num + sizeof(struct sharedslotdesc), NULL, globalpool);
        }
        if (rv != APR_SUCCESS) {
            return rv;
        }
        ptr = apr_shm_baseaddr_get(res->shm);
        desc.item_size = item_size;
        desc.item_num = item_num;
        memcpy(ptr, &desc, sizeof(desc));
        ptr = ptr +  sizeof(desc);
        memset(ptr, 0, item_size * item_num);
        restore_slotmem(ptr, fname, item_size, item_num, pool);  
    }

    /* For the chained slotmem stuff */
    res->name = apr_pstrdup(globalpool, fname);
    res->base = ptr;
    res->size = item_size;
    res->num = item_num;
    res->globalpool = globalpool;
    res->next = NULL;
    if (globallistmem==NULL)
        globallistmem = res;
    else
        next->next = res;

    *new = res;
    return APR_SUCCESS;
}
static apr_status_t ap_slotmem_attach(ap_slotmem_t **new, const char *name, apr_size_t *item_size, int *item_num, apr_pool_t *pool)
{
    void *slotmem = NULL;
    void *ptr;
    ap_slotmem_t *res;
    ap_slotmem_t *next = globallistmem;
    struct sharedslotdesc desc;
    const char *fname;
    apr_status_t rv;

    if (globalpool == NULL)
        return APR_ENOSHMAVAIL;
    if (name) {
        if (name[0] == ':')
            fname = name;
        else
            fname = ap_server_root_relative(pool, name);
    } else
        return APR_ENOSHMAVAIL;

    /* first try to attach to existing slotmem */
    if (next) {
        for (;;) {
            if (strcmp(next->name, fname) == 0) {
                /* we already have it */
                *new = next;
                *item_size = next->size;
                *item_num = next->num;
                return APR_SUCCESS;
            }
            if (!next->next)
                break;
            next = next->next;
        }
    }

    /* first try to attach to existing shared memory */
    res = (ap_slotmem_t *) apr_pcalloc(globalpool, sizeof(ap_slotmem_t));
    rv = apr_shm_attach(&res->shm, fname, globalpool);
    if (rv != APR_SUCCESS)
        return rv;

    /* Read the description of the slotmem */
    ptr = apr_shm_baseaddr_get(res->shm);
    memcpy(&desc, ptr, sizeof(desc));
    ptr = ptr + sizeof(desc);

    /* For the chained slotmem stuff */
    res->name = apr_pstrdup(globalpool, fname);
    res->base = ptr;
    res->size = desc.item_size;
    res->num = desc.item_num;
    res->globalpool = globalpool;
    res->next = NULL;
    if (globallistmem==NULL)
        globallistmem = res;
    else
        next->next = res;

    *new = res;
    *item_size = desc.item_size;
    *item_num = desc.item_num;
    return APR_SUCCESS;
}
static apr_status_t ap_slotmem_mem(ap_slotmem_t *score, int id, void**mem)
{

    void *ptr;

    if (!score)
        return APR_ENOSHMAVAIL;
    if (id<0 || id>score->num)
        return APR_ENOSHMAVAIL;

    ptr = score->base + score->size * id;
    if (!ptr)
        return APR_ENOSHMAVAIL;
    ptr = score->base + score->size * id;
    *mem = ptr;
    return APR_SUCCESS;
}

static const slotmem_storage_method storage = {
    &ap_slotmem_do,
    &ap_slotmem_create,
    &ap_slotmem_attach,
    &ap_slotmem_mem
};

/* make the storage usuable from outside */
const slotmem_storage_method *sharedmem_getstorage()
{
    return(&storage);
}
/* initialise the global pool */
void sharedmem_initglobalpool(apr_pool_t *p)
{
    globalpool = p;
}
/* Add the pool_clean routine */
void sharedmem_initialize_cleanup(apr_pool_t *p)
{
    apr_pool_cleanup_register(p, &globallistmem, cleanup_slotmem, apr_pool_cleanup_null);
}