diff options
Diffstat (limited to 'modules/cache/mod_mem_cache.c')
| -rw-r--r-- | modules/cache/mod_mem_cache.c | 1095 |
1 files changed, 1095 insertions, 0 deletions
diff --git a/modules/cache/mod_mem_cache.c b/modules/cache/mod_mem_cache.c new file mode 100644 index 00000000..b9c6915d --- /dev/null +++ b/modules/cache/mod_mem_cache.c @@ -0,0 +1,1095 @@ +/* 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. + */ + +/* + * Rules for managing obj->refcount: + * refcount should be incremented when an object is placed in the cache. Insertion + * of an object into the cache and the refcount increment should happen under + * protection of the sconf->lock. + * + * refcount should be decremented when the object is removed from the cache. + * Object should be removed from the cache and the refcount decremented while + * under protection of the sconf->lock. + * + * refcount should be incremented when an object is retrieved from the cache + * by a worker thread. The retrieval/find operation and refcount increment + * should occur under protection of the sconf->lock + * + * refcount can be atomically decremented w/o protection of the sconf->lock + * by worker threads. + * + * Any object whose refcount drops to 0 should be freed/cleaned up. A refcount + * of 0 means the object is not in the cache and no worker threads are accessing + * it. + */ +#define CORE_PRIVATE +#include "mod_cache.h" +#include "cache_pqueue.h" +#include "cache_cache.h" +#include "ap_provider.h" +#include "ap_mpm.h" +#include "apr_thread_mutex.h" +#if APR_HAVE_UNISTD_H +#include <unistd.h> +#endif + +#if !APR_HAS_THREADS +#error This module does not currently compile unless you have a thread-capable APR. Sorry! +#endif + +module AP_MODULE_DECLARE_DATA mem_cache_module; + +typedef enum { + CACHE_TYPE_FILE = 1, + CACHE_TYPE_HEAP, + CACHE_TYPE_MMAP +} cache_type_e; + +typedef struct { + char* hdr; + char* val; +} cache_header_tbl_t; + +typedef struct mem_cache_object { + cache_type_e type; + apr_ssize_t num_header_out; + apr_ssize_t num_req_hdrs; + cache_header_tbl_t *header_out; + cache_header_tbl_t *req_hdrs; /* for Vary negotiation */ + apr_size_t m_len; + void *m; + apr_os_file_t fd; + apr_int32_t flags; /* File open flags */ + long priority; /**< the priority of this entry */ + long total_refs; /**< total number of references this entry has had */ + + apr_uint32_t pos; /**< the position of this entry in the cache */ + +} mem_cache_object_t; + +typedef struct { + apr_thread_mutex_t *lock; + cache_cache_t *cache_cache; + + /* Fields set by config directives */ + apr_size_t min_cache_object_size; /* in bytes */ + apr_size_t max_cache_object_size; /* in bytes */ + apr_size_t max_cache_size; /* in bytes */ + apr_size_t max_object_cnt; + cache_pqueue_set_priority cache_remove_algorithm; + + /* maximum amount of data to buffer on a streamed response where + * we haven't yet seen EOS */ + apr_off_t max_streaming_buffer_size; +} mem_cache_conf; +static mem_cache_conf *sconf; + +#define DEFAULT_MAX_CACHE_SIZE 100*1024 +#define DEFAULT_MIN_CACHE_OBJECT_SIZE 0 +#define DEFAULT_MAX_CACHE_OBJECT_SIZE 10000 +#define DEFAULT_MAX_OBJECT_CNT 1009 +#define DEFAULT_MAX_STREAMING_BUFFER_SIZE 100000 +#define CACHEFILE_LEN 20 + +/* Forward declarations */ +static int remove_entity(cache_handle_t *h); +static apr_status_t store_headers(cache_handle_t *h, request_rec *r, cache_info *i); +static apr_status_t store_body(cache_handle_t *h, request_rec *r, apr_bucket_brigade *b); +static apr_status_t recall_headers(cache_handle_t *h, request_rec *r); +static apr_status_t recall_body(cache_handle_t *h, apr_pool_t *p, apr_bucket_brigade *bb); + +static void cleanup_cache_object(cache_object_t *obj); + +static long memcache_get_priority(void*a) +{ + cache_object_t *obj = (cache_object_t *)a; + mem_cache_object_t *mobj = obj->vobj; + + return mobj->priority; +} + +static void memcache_inc_frequency(void*a) +{ + cache_object_t *obj = (cache_object_t *)a; + mem_cache_object_t *mobj = obj->vobj; + + mobj->total_refs++; + mobj->priority = 0; +} + +static void memcache_set_pos(void *a, apr_ssize_t pos) +{ + cache_object_t *obj = (cache_object_t *)a; + mem_cache_object_t *mobj = obj->vobj; + + apr_atomic_set32(&mobj->pos, pos); +} +static apr_ssize_t memcache_get_pos(void *a) +{ + cache_object_t *obj = (cache_object_t *)a; + mem_cache_object_t *mobj = obj->vobj; + + return apr_atomic_read32(&mobj->pos); +} + +static apr_size_t memcache_cache_get_size(void*a) +{ + cache_object_t *obj = (cache_object_t *)a; + mem_cache_object_t *mobj = obj->vobj; + return mobj->m_len; +} +/** callback to get the key of a item */ +static const char* memcache_cache_get_key(void*a) +{ + cache_object_t *obj = (cache_object_t *)a; + return obj->key; +} +/** + * memcache_cache_free() + * memcache_cache_free is a callback that is only invoked by a thread + * running in cache_insert(). cache_insert() runs under protection + * of sconf->lock. By the time this function has been entered, the cache_object + * has been ejected from the cache. decrement the refcount and if the refcount drops + * to 0, cleanup the cache object. + */ +static void memcache_cache_free(void*a) +{ + cache_object_t *obj = (cache_object_t *)a; + + /* Decrement the refcount to account for the object being ejected + * from the cache. If the refcount is 0, free the object. + */ + if (!apr_atomic_dec32(&obj->refcount)) { + cleanup_cache_object(obj); + } +} +/* + * functions return a 'negative' score since priority queues + * dequeue the object with the highest value first + */ +static long memcache_lru_algorithm(long queue_clock, void *a) +{ + cache_object_t *obj = (cache_object_t *)a; + mem_cache_object_t *mobj = obj->vobj; + if (mobj->priority == 0) + mobj->priority = queue_clock - mobj->total_refs; + + /* + * a 'proper' LRU function would just be + * mobj->priority = mobj->total_refs; + */ + return mobj->priority; +} + +static long memcache_gdsf_algorithm(long queue_clock, void *a) +{ + cache_object_t *obj = (cache_object_t *)a; + mem_cache_object_t *mobj = obj->vobj; + + if (mobj->priority == 0) + mobj->priority = queue_clock - + (long)(mobj->total_refs*1000 / mobj->m_len); + + return mobj->priority; +} + +static void cleanup_cache_object(cache_object_t *obj) +{ + mem_cache_object_t *mobj = obj->vobj; + + /* TODO: + * We desperately need a more efficient way of allocating objects. We're + * making way too many malloc calls to create a fully populated + * cache object... + */ + + /* Cleanup the cache_object_t */ + if (obj->key) { + free((void*)obj->key); + } + + free(obj); + + /* Cleanup the mem_cache_object_t */ + if (mobj) { + if (mobj->type == CACHE_TYPE_HEAP && mobj->m) { + free(mobj->m); + } + if (mobj->type == CACHE_TYPE_FILE && mobj->fd) { +#ifdef WIN32 + CloseHandle(mobj->fd); +#else + close(mobj->fd); +#endif + } + if (mobj->header_out) { + if (mobj->header_out[0].hdr) + free(mobj->header_out[0].hdr); + free(mobj->header_out); + } + if (mobj->req_hdrs) { + if (mobj->req_hdrs[0].hdr) + free(mobj->req_hdrs[0].hdr); + free(mobj->req_hdrs); + } + free(mobj); + } +} +static apr_status_t decrement_refcount(void *arg) +{ + cache_object_t *obj = (cache_object_t *) arg; + + /* If obj->complete is not set, the cache update failed and the + * object needs to be removed from the cache then cleaned up. + * The garbage collector may have ejected the object from the + * cache already, so make sure it is really still in the cache + * before attempting to remove it. + */ + if (!obj->complete) { + cache_object_t *tobj = NULL; + if (sconf->lock) { + apr_thread_mutex_lock(sconf->lock); + } + tobj = cache_find(sconf->cache_cache, obj->key); + if (tobj == obj) { + cache_remove(sconf->cache_cache, obj); + apr_atomic_dec32(&obj->refcount); + } + if (sconf->lock) { + apr_thread_mutex_unlock(sconf->lock); + } + } + + /* If the refcount drops to 0, cleanup the cache object */ + if (!apr_atomic_dec32(&obj->refcount)) { + cleanup_cache_object(obj); + } + return APR_SUCCESS; +} +static apr_status_t cleanup_cache_mem(void *sconfv) +{ + cache_object_t *obj; + mem_cache_conf *co = (mem_cache_conf*) sconfv; + + if (!co) { + return APR_SUCCESS; + } + if (!co->cache_cache) { + return APR_SUCCESS; + } + + if (sconf->lock) { + apr_thread_mutex_lock(sconf->lock); + } + obj = cache_pop(co->cache_cache); + while (obj) { + /* Iterate over the cache and clean up each unreferenced entry */ + if (!apr_atomic_dec32(&obj->refcount)) { + cleanup_cache_object(obj); + } + obj = cache_pop(co->cache_cache); + } + + /* Cache is empty, free the cache table */ + cache_free(co->cache_cache); + + if (sconf->lock) { + apr_thread_mutex_unlock(sconf->lock); + } + return APR_SUCCESS; +} +/* + * TODO: enable directives to be overridden in various containers + */ +static void *create_cache_config(apr_pool_t *p, server_rec *s) +{ + sconf = apr_pcalloc(p, sizeof(mem_cache_conf)); + + sconf->min_cache_object_size = DEFAULT_MIN_CACHE_OBJECT_SIZE; + sconf->max_cache_object_size = DEFAULT_MAX_CACHE_OBJECT_SIZE; + /* Number of objects in the cache */ + sconf->max_object_cnt = DEFAULT_MAX_OBJECT_CNT; + /* Size of the cache in bytes */ + sconf->max_cache_size = DEFAULT_MAX_CACHE_SIZE; + sconf->cache_cache = NULL; + sconf->cache_remove_algorithm = memcache_gdsf_algorithm; + sconf->max_streaming_buffer_size = DEFAULT_MAX_STREAMING_BUFFER_SIZE; + + return sconf; +} + +static int create_entity(cache_handle_t *h, cache_type_e type_e, + request_rec *r, const char *key, apr_off_t len) +{ + cache_object_t *obj, *tmp_obj; + mem_cache_object_t *mobj; + apr_size_t key_len; + + if (len == -1) { + /* Caching a streaming response. Assume the response is + * less than or equal to max_streaming_buffer_size. We will + * correct all the cache size counters in store_body once + * we know exactly know how much we are caching. + */ + len = sconf->max_streaming_buffer_size; + } + + /* Note: cache_insert() will automatically garbage collect + * objects from the cache if the max_cache_size threshold is + * exceeded. This means mod_mem_cache does not need to implement + * max_cache_size checks. + */ + if (len < sconf->min_cache_object_size || + len > sconf->max_cache_object_size) { + ap_log_error(APLOG_MARK, APLOG_DEBUG, 0, r->server, + "mem_cache: URL %s failed the size check and will not be cached.", + key); + return DECLINED; + } + + if (type_e == CACHE_TYPE_FILE) { + /* CACHE_TYPE_FILE is only valid for local content handled by the + * default handler. Need a better way to check if the file is + * local or not. + */ + if (!r->filename) { + return DECLINED; + } + } + + /* Allocate and initialize cache_object_t */ + obj = calloc(1, sizeof(*obj)); + if (!obj) { + return DECLINED; + } + key_len = strlen(key) + 1; + obj->key = malloc(key_len); + if (!obj->key) { + cleanup_cache_object(obj); + return DECLINED; + } + memcpy((void*)obj->key, key, key_len); + + /* Allocate and init mem_cache_object_t */ + mobj = calloc(1, sizeof(*mobj)); + if (!mobj) { + cleanup_cache_object(obj); + return DECLINED; + } + + /* Finish initing the cache object */ + apr_atomic_set32(&obj->refcount, 1); + mobj->total_refs = 1; + obj->complete = 0; + obj->vobj = mobj; + /* Safe cast: We tested < sconf->max_cache_object_size above */ + mobj->m_len = (apr_size_t)len; + mobj->type = type_e; + + /* Place the cache_object_t into the hash table. + * Note: Perhaps we should wait to put the object in the + * hash table when the object is complete? I add the object here to + * avoid multiple threads attempting to cache the same content only + * to discover at the very end that only one of them will succeed. + * Furthermore, adding the cache object to the table at the end could + * open up a subtle but easy to exploit DoS hole: someone could request + * a very large file with multiple requests. Better to detect this here + * rather than after the cache object has been completely built and + * initialized... + * XXX Need a way to insert into the cache w/o such coarse grained locking + */ + if (sconf->lock) { + apr_thread_mutex_lock(sconf->lock); + } + tmp_obj = (cache_object_t *) cache_find(sconf->cache_cache, key); + + if (!tmp_obj) { + cache_insert(sconf->cache_cache, obj); + /* Add a refcount to account for the reference by the + * hashtable in the cache. Refcount should be 2 now, one + * for this thread, and one for the cache. + */ + apr_atomic_inc32(&obj->refcount); + } + if (sconf->lock) { + apr_thread_mutex_unlock(sconf->lock); + } + + if (tmp_obj) { + /* This thread collided with another thread loading the same object + * into the cache at the same time. Defer to the other thread which + * is further along. + */ + cleanup_cache_object(obj); + return DECLINED; + } + + apr_pool_cleanup_register(r->pool, obj, decrement_refcount, + apr_pool_cleanup_null); + + /* Populate the cache handle */ + h->cache_obj = obj; + + return OK; +} + +static int create_mem_entity(cache_handle_t *h, request_rec *r, + const char *key, apr_off_t len) +{ + return create_entity(h, CACHE_TYPE_HEAP, r, key, len); +} + +static int create_fd_entity(cache_handle_t *h, request_rec *r, + const char *key, apr_off_t len) +{ + return create_entity(h, CACHE_TYPE_FILE, r, key, len); +} + +static int open_entity(cache_handle_t *h, request_rec *r, const char *key) +{ + cache_object_t *obj; + + /* Look up entity keyed to 'url' */ + if (sconf->lock) { + apr_thread_mutex_lock(sconf->lock); + } + obj = (cache_object_t *) cache_find(sconf->cache_cache, key); + if (obj) { + if (obj->complete) { + request_rec *rmain=r, *rtmp; + apr_atomic_inc32(&obj->refcount); + /* cache is worried about overall counts, not 'open' ones */ + cache_update(sconf->cache_cache, obj); + + /* If this is a subrequest, register the cleanup against + * the main request. This will prevent the cache object + * from being cleaned up from under the request after the + * subrequest is destroyed. + */ + rtmp = r; + while (rtmp) { + rmain = rtmp; + rtmp = rmain->main; + } + apr_pool_cleanup_register(rmain->pool, obj, decrement_refcount, + apr_pool_cleanup_null); + } + else { + obj = NULL; + } + } + + if (sconf->lock) { + apr_thread_mutex_unlock(sconf->lock); + } + + if (!obj) { + return DECLINED; + } + + /* Initialize the cache_handle */ + h->cache_obj = obj; + h->req_hdrs = NULL; /* Pick these up in recall_headers() */ + return OK; +} + +/* remove_entity() + * Notes: + * refcount should be at least 1 upon entry to this function to account + * for this thread's reference to the object. If the refcount is 1, then + * object has been removed from the cache by another thread and this thread + * is the last thread accessing the object. + */ +static int remove_entity(cache_handle_t *h) +{ + cache_object_t *obj = h->cache_obj; + cache_object_t *tobj = NULL; + + if (sconf->lock) { + apr_thread_mutex_lock(sconf->lock); + } + + /* If the entity is still in the cache, remove it and decrement the + * refcount. If the entity is not in the cache, do nothing. In both cases + * decrement_refcount called by the last thread referencing the object will + * trigger the cleanup. + */ + tobj = cache_find(sconf->cache_cache, obj->key); + if (tobj == obj) { + cache_remove(sconf->cache_cache, obj); + apr_atomic_dec32(&obj->refcount); + } + + if (sconf->lock) { + apr_thread_mutex_unlock(sconf->lock); + } + + return OK; +} +static apr_status_t serialize_table(cache_header_tbl_t **obj, + apr_ssize_t *nelts, + apr_table_t *table) +{ + const apr_array_header_t *elts_arr = apr_table_elts(table); + apr_table_entry_t *elts = (apr_table_entry_t *) elts_arr->elts; + apr_ssize_t i; + apr_size_t len = 0; + apr_size_t idx = 0; + char *buf; + + *nelts = elts_arr->nelts; + if (*nelts == 0 ) { + *obj=NULL; + return APR_SUCCESS; + } + *obj = malloc(sizeof(cache_header_tbl_t) * elts_arr->nelts); + if (NULL == *obj) { + return APR_ENOMEM; + } + for (i = 0; i < elts_arr->nelts; ++i) { + len += strlen(elts[i].key); + len += strlen(elts[i].val); + len += 2; /* Extra space for NULL string terminator for key and val */ + } + + /* Transfer the headers into a contiguous memory block */ + buf = malloc(len); + if (!buf) { + *obj = NULL; + return APR_ENOMEM; + } + + for (i = 0; i < *nelts; ++i) { + (*obj)[i].hdr = &buf[idx]; + len = strlen(elts[i].key) + 1; /* Include NULL terminator */ + memcpy(&buf[idx], elts[i].key, len); + idx+=len; + + (*obj)[i].val = &buf[idx]; + len = strlen(elts[i].val) + 1; + memcpy(&buf[idx], elts[i].val, len); + idx+=len; + } + return APR_SUCCESS; +} +static int unserialize_table( cache_header_tbl_t *ctbl, + int num_headers, + apr_table_t *t ) +{ + int i; + + for (i = 0; i < num_headers; ++i) { + apr_table_addn(t, ctbl[i].hdr, ctbl[i].val); + } + + return APR_SUCCESS; +} +/* Define request processing hook handlers */ +/* remove_url() + * Notes: + */ +static int remove_url(cache_handle_t *h, apr_pool_t *p) +{ + cache_object_t *obj; + int cleanup = 0; + + if (sconf->lock) { + apr_thread_mutex_lock(sconf->lock); + } + + obj = h->cache_obj; + if (obj) { + cache_remove(sconf->cache_cache, obj); + /* For performance, cleanup cache object after releasing the lock */ + cleanup = !apr_atomic_dec32(&obj->refcount); + } + if (sconf->lock) { + apr_thread_mutex_unlock(sconf->lock); + } + + if (cleanup) { + cleanup_cache_object(obj); + } + + return OK; +} + +static apr_status_t recall_headers(cache_handle_t *h, request_rec *r) +{ + int rc; + mem_cache_object_t *mobj = (mem_cache_object_t*) h->cache_obj->vobj; + + h->req_hdrs = apr_table_make(r->pool, mobj->num_req_hdrs); + h->resp_hdrs = apr_table_make(r->pool, mobj->num_header_out); + + rc = unserialize_table(mobj->req_hdrs, mobj->num_req_hdrs, h->req_hdrs); + rc = unserialize_table(mobj->header_out, mobj->num_header_out, + h->resp_hdrs); + + return rc; +} + +static apr_status_t recall_body(cache_handle_t *h, apr_pool_t *p, apr_bucket_brigade *bb) +{ + apr_bucket *b; + mem_cache_object_t *mobj = (mem_cache_object_t*) h->cache_obj->vobj; + + if (mobj->type == CACHE_TYPE_FILE) { + /* CACHE_TYPE_FILE */ + apr_file_t *file; + apr_os_file_put(&file, &mobj->fd, mobj->flags, p); + b = apr_bucket_file_create(file, 0, mobj->m_len, p, bb->bucket_alloc); + } + else { + /* CACHE_TYPE_HEAP */ + b = apr_bucket_immortal_create(mobj->m, mobj->m_len, bb->bucket_alloc); + } + APR_BRIGADE_INSERT_TAIL(bb, b); + b = apr_bucket_eos_create(bb->bucket_alloc); + APR_BRIGADE_INSERT_TAIL(bb, b); + + return APR_SUCCESS; +} + + +static apr_status_t store_headers(cache_handle_t *h, request_rec *r, cache_info *info) +{ + cache_object_t *obj = h->cache_obj; + mem_cache_object_t *mobj = (mem_cache_object_t*) obj->vobj; + int rc; + apr_table_t *headers_out; + + /* + * The cache needs to keep track of the following information: + * - Date, LastMod, Version, ReqTime, RespTime, ContentLength + * - The original request headers (for Vary) + * - The original response headers (for returning with a cached response) + * - The body of the message + */ + rc = serialize_table(&mobj->req_hdrs, + &mobj->num_req_hdrs, + r->headers_in); + if (rc != APR_SUCCESS) { + return rc; + } + + /* Precompute how much storage we need to hold the headers */ + headers_out = ap_cache_cacheable_hdrs_out(r->pool, r->headers_out, + r->server); + + /* If not set in headers_out, set Content-Type */ + if (!apr_table_get(headers_out, "Content-Type") + && r->content_type) { + apr_table_setn(headers_out, "Content-Type", + ap_make_content_type(r, r->content_type)); + } + + headers_out = apr_table_overlay(r->pool, headers_out, r->err_headers_out); + + rc = serialize_table(&mobj->header_out, &mobj->num_header_out, + headers_out); + if (rc != APR_SUCCESS) { + return rc; + } + + /* Init the info struct */ + obj->info.status = info->status; + if (info->date) { + obj->info.date = info->date; + } + if (info->response_time) { + obj->info.response_time = info->response_time; + } + if (info->request_time) { + obj->info.request_time = info->request_time; + } + if (info->expire) { + obj->info.expire = info->expire; + } + + return APR_SUCCESS; +} + +static apr_status_t store_body(cache_handle_t *h, request_rec *r, apr_bucket_brigade *b) +{ + apr_status_t rv; + cache_object_t *obj = h->cache_obj; + cache_object_t *tobj = NULL; + mem_cache_object_t *mobj = (mem_cache_object_t*) obj->vobj; + apr_read_type_e eblock = APR_BLOCK_READ; + apr_bucket *e; + char *cur; + int eos = 0; + + if (mobj->type == CACHE_TYPE_FILE) { + apr_file_t *file = NULL; + int fd = 0; + int other = 0; + + /* We can cache an open file descriptor if: + * - the brigade contains one and only one file_bucket && + * - the brigade is complete && + * - the file_bucket is the last data bucket in the brigade + */ + for (e = APR_BRIGADE_FIRST(b); + e != APR_BRIGADE_SENTINEL(b); + e = APR_BUCKET_NEXT(e)) + { + if (APR_BUCKET_IS_EOS(e)) { + eos = 1; + } + else if (APR_BUCKET_IS_FILE(e)) { + apr_bucket_file *a = e->data; + fd++; + file = a->fd; + } + else { + other++; + } + } + if (fd == 1 && !other && eos) { + apr_file_t *tmpfile; + const char *name; + /* Open a new XTHREAD handle to the file */ + apr_file_name_get(&name, file); + mobj->flags = ((APR_SENDFILE_ENABLED & apr_file_flags_get(file)) + | APR_READ | APR_BINARY | APR_XTHREAD | APR_FILE_NOCLEANUP); + rv = apr_file_open(&tmpfile, name, mobj->flags, + APR_OS_DEFAULT, r->pool); + if (rv != APR_SUCCESS) { + return rv; + } + apr_file_inherit_unset(tmpfile); + apr_os_file_get(&(mobj->fd), tmpfile); + + /* Open for business */ + ap_log_error(APLOG_MARK, APLOG_INFO, 0, r->server, + "mem_cache: Cached file: %s with key: %s", name, obj->key); + obj->complete = 1; + return APR_SUCCESS; + } + + /* Content not suitable for fd caching. Cache in-memory instead. */ + mobj->type = CACHE_TYPE_HEAP; + } + + /* + * FD cacheing is not enabled or the content was not + * suitable for fd caching. + */ + if (mobj->m == NULL) { + mobj->m = malloc(mobj->m_len); + if (mobj->m == NULL) { + return APR_ENOMEM; + } + obj->count = 0; + } + cur = (char*) mobj->m + obj->count; + + /* Iterate accross the brigade and populate the cache storage */ + for (e = APR_BRIGADE_FIRST(b); + e != APR_BRIGADE_SENTINEL(b); + e = APR_BUCKET_NEXT(e)) + { + const char *s; + apr_size_t len; + + if (APR_BUCKET_IS_EOS(e)) { + if (mobj->m_len > obj->count) { + /* Caching a streamed response. Reallocate a buffer of the + * correct size and copy the streamed response into that + * buffer */ + char *buf = malloc(obj->count); + if (!buf) { + return APR_ENOMEM; + } + memcpy(buf, mobj->m, obj->count); + free(mobj->m); + mobj->m = buf; + + /* Now comes the crufty part... there is no way to tell the + * cache that the size of the object has changed. We need + * to remove the object, update the size and re-add the + * object, all under protection of the lock. + */ + if (sconf->lock) { + apr_thread_mutex_lock(sconf->lock); + } + /* Has the object been ejected from the cache? + */ + tobj = (cache_object_t *) cache_find(sconf->cache_cache, obj->key); + if (tobj == obj) { + /* Object is still in the cache, remove it, update the len field then + * replace it under protection of sconf->lock. + */ + cache_remove(sconf->cache_cache, obj); + /* For illustration, cache no longer has reference to the object + * so decrement the refcount + * apr_atomic_dec32(&obj->refcount); + */ + mobj->m_len = obj->count; + + cache_insert(sconf->cache_cache, obj); + /* For illustration, cache now has reference to the object, so + * increment the refcount + * apr_atomic_inc32(&obj->refcount); + */ + } + else if (tobj) { + /* Different object with the same key found in the cache. Doing nothing + * here will cause the object refcount to drop to 0 in decrement_refcount + * and the object will be cleaned up. + */ + + } else { + /* Object has been ejected from the cache, add it back to the cache */ + mobj->m_len = obj->count; + cache_insert(sconf->cache_cache, obj); + apr_atomic_inc32(&obj->refcount); + } + + if (sconf->lock) { + apr_thread_mutex_unlock(sconf->lock); + } + } + /* Open for business */ + ap_log_error(APLOG_MARK, APLOG_INFO, 0, r->server, + "mem_cache: Cached url: %s", obj->key); + obj->complete = 1; + break; + } + rv = apr_bucket_read(e, &s, &len, eblock); + if (rv != APR_SUCCESS) { + return rv; + } + if (len) { + /* Check for buffer overflow */ + if ((obj->count + len) > mobj->m_len) { + return APR_ENOMEM; + } + else { + memcpy(cur, s, len); + cur+=len; + obj->count+=len; + } + } + /* This should not fail, but if it does, we are in BIG trouble + * cause we just stomped all over the heap. + */ + AP_DEBUG_ASSERT(obj->count <= mobj->m_len); + } + return APR_SUCCESS; +} +/** + * Configuration and start-up + */ +static int mem_cache_post_config(apr_pool_t *p, apr_pool_t *plog, + apr_pool_t *ptemp, server_rec *s) +{ + int threaded_mpm; + + /* Sanity check the cache configuration */ + if (sconf->min_cache_object_size >= sconf->max_cache_object_size) { + ap_log_error(APLOG_MARK, APLOG_CRIT, 0, s, + "MCacheMaxObjectSize must be greater than MCacheMinObjectSize"); + return DONE; + } + if (sconf->max_cache_object_size >= sconf->max_cache_size) { + ap_log_error(APLOG_MARK, APLOG_CRIT, 0, s, + "MCacheSize must be greater than MCacheMaxObjectSize"); + return DONE; + } + if (sconf->max_streaming_buffer_size > sconf->max_cache_object_size) { + /* Issue a notice only if something other than the default config + * is being used */ + if (sconf->max_streaming_buffer_size != DEFAULT_MAX_STREAMING_BUFFER_SIZE && + sconf->max_cache_object_size != DEFAULT_MAX_CACHE_OBJECT_SIZE) { + ap_log_error(APLOG_MARK, APLOG_NOTICE, 0, s, + "MCacheMaxStreamingBuffer must be less than or equal to MCacheMaxObjectSize. " + "Resetting MCacheMaxStreamingBuffer to MCacheMaxObjectSize."); + } + sconf->max_streaming_buffer_size = sconf->max_cache_object_size; + } + if (sconf->max_streaming_buffer_size < sconf->min_cache_object_size) { + ap_log_error(APLOG_MARK, APLOG_WARNING, 0, s, + "MCacheMaxStreamingBuffer must be greater than or equal to MCacheMinObjectSize. " + "Resetting MCacheMaxStreamingBuffer to MCacheMinObjectSize."); + sconf->max_streaming_buffer_size = sconf->min_cache_object_size; + } + ap_mpm_query(AP_MPMQ_IS_THREADED, &threaded_mpm); + if (threaded_mpm) { + apr_thread_mutex_create(&sconf->lock, APR_THREAD_MUTEX_DEFAULT, p); + } + + sconf->cache_cache = cache_init(sconf->max_object_cnt, + sconf->max_cache_size, + memcache_get_priority, + sconf->cache_remove_algorithm, + memcache_get_pos, + memcache_set_pos, + memcache_inc_frequency, + memcache_cache_get_size, + memcache_cache_get_key, + memcache_cache_free); + apr_pool_cleanup_register(p, sconf, cleanup_cache_mem, apr_pool_cleanup_null); + + if (sconf->cache_cache) + return OK; + + return -1; + +} + +static const char +*set_max_cache_size(cmd_parms *parms, void *in_struct_ptr, const char *arg) +{ + apr_size_t val; + + if (sscanf(arg, "%" APR_SIZE_T_FMT, &val) != 1) { + return "MCacheSize argument must be an integer representing the max cache size in KBytes."; + } + sconf->max_cache_size = val*1024; + return NULL; +} +static const char +*set_min_cache_object_size(cmd_parms *parms, void *in_struct_ptr, const char *arg) +{ + apr_size_t val; + + if (sscanf(arg, "%" APR_SIZE_T_FMT, &val) != 1) { + return "MCacheMinObjectSize value must be an integer (bytes)"; + } + sconf->min_cache_object_size = val; + return NULL; +} +static const char +*set_max_cache_object_size(cmd_parms *parms, void *in_struct_ptr, const char *arg) +{ + apr_size_t val; + + if (sscanf(arg, "%" APR_SIZE_T_FMT, &val) != 1) { + return "MCacheMaxObjectSize value must be an integer (bytes)"; + } + sconf->max_cache_object_size = val; + return NULL; +} +static const char +*set_max_object_count(cmd_parms *parms, void *in_struct_ptr, const char *arg) +{ + apr_size_t val; + + if (sscanf(arg, "%" APR_SIZE_T_FMT, &val) != 1) { + return "MCacheMaxObjectCount value must be an integer"; + } + sconf->max_object_cnt = val; + return NULL; +} + +static const char +*set_cache_removal_algorithm(cmd_parms *parms, void *name, const char *arg) +{ + if (strcasecmp("LRU", arg)) { + sconf->cache_remove_algorithm = memcache_lru_algorithm; + } + else { + if (strcasecmp("GDSF", arg)) { + sconf->cache_remove_algorithm = memcache_gdsf_algorithm; + } + else { + return "currently implemented algorithms are LRU and GDSF"; + } + } + return NULL; +} + +static const char *set_max_streaming_buffer(cmd_parms *parms, void *dummy, + const char *arg) +{ + char *err; + if (apr_strtoff(&sconf->max_streaming_buffer_size, arg, &err, 10) || *err) { + return "MCacheMaxStreamingBuffer value must be a number"; + } + + return NULL; +} + +static const command_rec cache_cmds[] = +{ + AP_INIT_TAKE1("MCacheSize", set_max_cache_size, NULL, RSRC_CONF, + "The maximum amount of memory used by the cache in KBytes"), + AP_INIT_TAKE1("MCacheMaxObjectCount", set_max_object_count, NULL, RSRC_CONF, + "The maximum number of objects allowed to be placed in the cache"), + AP_INIT_TAKE1("MCacheMinObjectSize", set_min_cache_object_size, NULL, RSRC_CONF, + "The minimum size (in bytes) of an object to be placed in the cache"), + AP_INIT_TAKE1("MCacheMaxObjectSize", set_max_cache_object_size, NULL, RSRC_CONF, + "The maximum size (in bytes) of an object to be placed in the cache"), + AP_INIT_TAKE1("MCacheRemovalAlgorithm", set_cache_removal_algorithm, NULL, RSRC_CONF, + "The algorithm used to remove entries from the cache (default: GDSF)"), + AP_INIT_TAKE1("MCacheMaxStreamingBuffer", set_max_streaming_buffer, NULL, RSRC_CONF, + "Maximum number of bytes of content to buffer for a streamed response"), + {NULL} +}; + +static const cache_provider cache_mem_provider = +{ + &remove_entity, + &store_headers, + &store_body, + &recall_headers, + &recall_body, + &create_mem_entity, + &open_entity, + &remove_url, +}; + +static const cache_provider cache_fd_provider = +{ + &remove_entity, + &store_headers, + &store_body, + &recall_headers, + &recall_body, + &create_fd_entity, + &open_entity, + &remove_url, +}; + +static void register_hooks(apr_pool_t *p) +{ + ap_hook_post_config(mem_cache_post_config, NULL, NULL, APR_HOOK_MIDDLE); + /* cache initializer */ + /* cache_hook_init(cache_mem_init, NULL, NULL, APR_HOOK_MIDDLE); */ + /* + cache_hook_create_entity(create_entity, NULL, NULL, APR_HOOK_MIDDLE); + cache_hook_open_entity(open_entity, NULL, NULL, APR_HOOK_MIDDLE); + cache_hook_remove_url(remove_url, NULL, NULL, APR_HOOK_MIDDLE); + */ + ap_register_provider(p, CACHE_PROVIDER_GROUP, "mem", "0", + &cache_mem_provider); + ap_register_provider(p, CACHE_PROVIDER_GROUP, "fd", "0", + &cache_fd_provider); +} + +module AP_MODULE_DECLARE_DATA mem_cache_module = +{ + STANDARD20_MODULE_STUFF, + NULL, /* create per-directory config structure */ + NULL, /* merge per-directory config structures */ + create_cache_config, /* create per-server config structure */ + NULL, /* merge per-server config structures */ + cache_cmds, /* command apr_table_t */ + register_hooks +}; |