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database/apache/include/mod_cache.h

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+/* 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.
+ */
+
+/**
+ * @file mod_cache.h
+ * @brief Main include file for the Apache Transparent Cache
+ *
+ * @defgroup MOD_CACHE mod_cache
+ * @ingroup  APACHE_MODS
+ * @{
+ */
+
+#ifndef MOD_CACHE_H
+#define MOD_CACHE_H
+
+#include "httpd.h"
+#include "apr_date.h"
+#include "apr_optional.h"
+#include "apr_hooks.h"
+
+#include "cache_common.h"
+
+/* Create a set of CACHE_DECLARE(type), CACHE_DECLARE_NONSTD(type) and
+ * CACHE_DECLARE_DATA with appropriate export and import tags for the platform
+ */
+#if !defined(WIN32)
+#define CACHE_DECLARE(type)            type
+#define CACHE_DECLARE_NONSTD(type)     type
+#define CACHE_DECLARE_DATA
+#elif defined(CACHE_DECLARE_STATIC)
+#define CACHE_DECLARE(type)            type __stdcall
+#define CACHE_DECLARE_NONSTD(type)     type
+#define CACHE_DECLARE_DATA
+#elif defined(CACHE_DECLARE_EXPORT)
+#define CACHE_DECLARE(type)            __declspec(dllexport) type __stdcall
+#define CACHE_DECLARE_NONSTD(type)     __declspec(dllexport) type
+#define CACHE_DECLARE_DATA             __declspec(dllexport)
+#else
+#define CACHE_DECLARE(type)            __declspec(dllimport) type __stdcall
+#define CACHE_DECLARE_NONSTD(type)     __declspec(dllimport) type
+#define CACHE_DECLARE_DATA             __declspec(dllimport)
+#endif
+
+/* cache info information */
+typedef struct cache_info cache_info;
+struct cache_info {
+    /**
+     * the original time corresponding to the 'Date:' header of the request
+     * served
+     */
+    apr_time_t date;
+    /** a time when the cached entity is due to expire */
+    apr_time_t expire;
+    /** r->request_time from the same request */
+    apr_time_t request_time;
+    /** apr_time_now() at the time the entity was actually cached */
+    apr_time_t response_time;
+    /**
+     * HTTP status code of the cached entity. Though not necessarily the
+     * status code finally issued to the request.
+     */
+    int status;
+    /* cached cache-control */
+    cache_control_t control;
+};
+
+/* cache handle information */
+typedef struct cache_object cache_object_t;
+struct cache_object {
+    const char *key;
+    cache_object_t *next;
+    cache_info info;
+    /* Opaque portion (specific to the implementation) of the cache object */
+    void *vobj;
+};
+
+typedef struct cache_handle cache_handle_t;
+struct cache_handle {
+    cache_object_t *cache_obj;
+    apr_table_t *req_hdrs;        /* cached request headers */
+    apr_table_t *resp_hdrs;       /* cached response headers */
+};
+
+#define CACHE_PROVIDER_GROUP "cache"
+
+typedef struct {
+    int (*remove_entity) (cache_handle_t *h);
+    apr_status_t (*store_headers)(cache_handle_t *h, request_rec *r, cache_info *i);
+    apr_status_t (*store_body)(cache_handle_t *h, request_rec *r, apr_bucket_brigade *in,
+                           apr_bucket_brigade *out);
+    apr_status_t (*recall_headers) (cache_handle_t *h, request_rec *r);
+    apr_status_t (*recall_body) (cache_handle_t *h, apr_pool_t *p, apr_bucket_brigade *bb);
+    int (*create_entity) (cache_handle_t *h, request_rec *r,
+                           const char *urlkey, apr_off_t len, apr_bucket_brigade *bb);
+    int (*open_entity) (cache_handle_t *h, request_rec *r,
+                           const char *urlkey);
+    int (*remove_url) (cache_handle_t *h, request_rec *r);
+    apr_status_t (*commit_entity)(cache_handle_t *h, request_rec *r);
+    apr_status_t (*invalidate_entity)(cache_handle_t *h, request_rec *r);
+} cache_provider;
+
+typedef enum {
+    AP_CACHE_HIT,
+    AP_CACHE_REVALIDATE,
+    AP_CACHE_MISS,
+    AP_CACHE_INVALIDATE
+} ap_cache_status_e;
+
+#define AP_CACHE_HIT_ENV "cache-hit"
+#define AP_CACHE_REVALIDATE_ENV "cache-revalidate"
+#define AP_CACHE_MISS_ENV "cache-miss"
+#define AP_CACHE_INVALIDATE_ENV "cache-invalidate"
+#define AP_CACHE_STATUS_ENV "cache-status"
+
+
+/* cache_util.c */
+/* do a HTTP/1.1 age calculation */
+CACHE_DECLARE(apr_time_t) ap_cache_current_age(cache_info *info, const apr_time_t age_value,
+                                               apr_time_t now);
+
+CACHE_DECLARE(apr_time_t) ap_cache_hex2usec(const char *x);
+CACHE_DECLARE(void) ap_cache_usec2hex(apr_time_t j, char *y);
+CACHE_DECLARE(char *) ap_cache_generate_name(apr_pool_t *p, int dirlevels,
+                                             int dirlength,
+                                             const char *name);
+CACHE_DECLARE(const char *)ap_cache_tokstr(apr_pool_t *p, const char *list, const char **str);
+
+/* Create a new table consisting of those elements from an
+ * headers table that are allowed to be stored in a cache.
+ */
+CACHE_DECLARE(apr_table_t *)ap_cache_cacheable_headers(apr_pool_t *pool,
+                                                        apr_table_t *t,
+                                                        server_rec *s);
+
+/* Create a new table consisting of those elements from an input
+ * headers table that are allowed to be stored in a cache.
+ */
+CACHE_DECLARE(apr_table_t *)ap_cache_cacheable_headers_in(request_rec *r);
+
+/* Create a new table consisting of those elements from an output
+ * headers table that are allowed to be stored in a cache;
+ * ensure there is a content type and capture any errors.
+ */
+CACHE_DECLARE(apr_table_t *)ap_cache_cacheable_headers_out(request_rec *r);
+
+/**
+ * Parse the Cache-Control and Pragma headers in one go, marking
+ * which tokens appear within the header. Populate the structure
+ * passed in.
+ */
+int ap_cache_control(request_rec *r, cache_control_t *cc, const char *cc_header,
+        const char *pragma_header, apr_table_t *headers);
+
+
+/* hooks */
+
+/**
+ * Cache status hook.
+ * This hook is called as soon as the cache has made a decision as to whether
+ * an entity should be served from cache (hit), should be served from cache
+ * after a successful validation (revalidate), or served from the backend
+ * and potentially cached (miss).
+ *
+ * A basic implementation of this hook exists in mod_cache which writes this
+ * information to the subprocess environment, and optionally to request
+ * headers. Further implementations may add hooks as appropriate to perform
+ * more advanced processing, or to store statistics about the cache behaviour.
+ */
+APR_DECLARE_EXTERNAL_HOOK(cache, CACHE, int, cache_status, (cache_handle_t *h,
+                request_rec *r, apr_table_t *headers, ap_cache_status_e status,
+                const char *reason))
+
+APR_DECLARE_OPTIONAL_FN(apr_status_t,
+                        ap_cache_generate_key,
+                        (request_rec *r, apr_pool_t*p, const char **key));
+
+
+#endif /*MOD_CACHE_H*/
+/** @} */