llcache.h

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/*
 * Copyright 2009 John-Mark Bell <jmb@netsurf-browser.org>
 *
 * This file is part of NetSurf, http://www.netsurf-browser.org/
 *
 * NetSurf is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; version 2 of the License.
 *
 * NetSurf is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */
 
/** \file
 * Low-level resource cache (interface)
 */
 
#ifndef NETSURF_CONTENT_LLCACHE_H_
#define NETSURF_CONTENT_LLCACHE_H_
 
#include <stdbool.h>
#include <stddef.h>
#include <stdint.h>
 
#include "utils/errors.h"
#include "utils/nsurl.h"
 
struct cert_chain;
struct fetch_multipart_data;
 
/** Handle for low-level cache object */
typedef struct llcache_handle llcache_handle;
 
/** POST data object for low-level cache requests */
typedef struct llcache_post_data {
        enum {
                LLCACHE_POST_URL_ENCODED,
                LLCACHE_POST_MULTIPART
        } type;                         /**< Type of POST data */
        union {
                char *urlenc;           /**< URL encoded data */
                struct fetch_multipart_data *multipart; /**< Multipart data */
        } data;                         /**< POST data content */
} llcache_post_data;
 
/** Flags for low-level cache object retrieval */
enum llcache_retrieve_flag {
        /* Note: We're permitted a maximum of 16 flags which must reside in the
         * bottom 16 bits of the flags word. See hlcache.h for further details.
         */
        /** Force a new fetch */
        LLCACHE_RETRIEVE_FORCE_FETCH    = (1 << 0),
        /** Requested URL was verified */
        LLCACHE_RETRIEVE_VERIFIABLE     = (1 << 1),
        /**< No error pages */
        LLCACHE_RETRIEVE_NO_ERROR_PAGES = (1 << 2),
        /**< Stream data (implies that object is not cacheable) */
        LLCACHE_RETRIEVE_STREAM_DATA    = (1 << 3)
};
 
/** Low-level cache event types */
typedef enum {
        LLCACHE_EVENT_GOT_CERTS,        /**< SSL certificates arrived */
        LLCACHE_EVENT_HAD_HEADERS,      /**< Received all headers */
        LLCACHE_EVENT_HAD_DATA,         /**< Received some data */
        LLCACHE_EVENT_DONE,             /**< Finished fetching data */
 
        LLCACHE_EVENT_ERROR,            /**< An error occurred during fetch */
        LLCACHE_EVENT_PROGRESS,         /**< Fetch progress update */
 
        LLCACHE_EVENT_REDIRECT          /**< Fetch URL redirect occured */
} llcache_event_type;
 
/**
 * Low-level cache events.
 *
 * Lifetime of contained information is only for the duration of the event
 * and must be copied if it is desirable to retain.
 */
typedef struct {
        llcache_event_type type;            /**< Type of event */
        union {
                struct {
                        const uint8_t *buf; /**< Buffer of data */
                        size_t len;         /**< Byte length of buffer */
                } data;                     /**< Received data */
                struct {
                        nserror code;       /**< The error code */
                        const char *msg;    /**< Error message */
                } error;
                const char *progress_msg;   /**< Progress message */
                struct {
                        nsurl *from;        /**< Redirect origin */
                        nsurl *to;          /**< Redirect target */
                } redirect;                 /**< Fetch URL redirect occured */
                const struct cert_chain *chain;    /**< Certificate chain */
        } data;                             /**< Event data */
} llcache_event;
 
/**
 * Client callback for low-level cache events
 *
 * \param handle  Handle for which event is issued
 * \param event   Event data
 * \param pw      Pointer to client-specific data
 * \return NSERROR_OK on success, appropriate error otherwise.
 */
typedef nserror (*llcache_handle_callback)(llcache_handle *handle,
                const llcache_event *event, void *pw);
 
/**
 * Parameters to configure the low level cache backing store.
 */
struct llcache_store_parameters {
        const char *path; /**< The path to the backing store */
 
        size_t limit; /**< The backing store upper bound target size */
        size_t hysteresis; /**< The hysteresis around the target size */
};
 
/**
 * Parameters to configure the low level cache.
 */
struct llcache_parameters {
        size_t limit; /**< The target upper bound for the RAM cache size */
        size_t hysteresis; /**< The hysteresis around the target size */
 
        /** The minimum lifetime to consider sending objects to backing store.*/
        int minimum_lifetime;
 
        /** The minimum bandwidth to allow the backing store to
         * use in bytes/second
         */
        size_t minimum_bandwidth;
 
        /** The maximum bandwidth to allow the backing store to use in
         * bytes/second
         */
        size_t maximum_bandwidth;
 
        /** The time quantum over which to calculate the bandwidth values
         */
        unsigned long time_quantum;
 
        /** The number of fetches to attempt when timing out */
        uint32_t fetch_attempts;
 
        struct llcache_store_parameters store;
};
 
/**
 * Initialise the low-level cache
 *
 * \param parameters cache configuration parameters.
 * \return NSERROR_OK on success, appropriate error otherwise.
 */
nserror llcache_initialise(const struct llcache_parameters *parameters);
 
/**
 * Finalise the low-level cache
 */
void llcache_finalise(void);
 
/**
 * Cause the low-level cache to attempt to perform cleanup.
 *
 * No guarantees are made as to whether or not cleanups will take
 * place and what, if any, space savings will be made.
 *
 * \param purge Any objects held in the cache that are safely removable will
 *              be freed regardless of the configured size limits.
 */
void llcache_clean(bool purge);
 
/**
 * Retrieve a handle for a low-level cache object
 *
 * \param url      URL of the object to fetch
 * \param flags    Object retrieval flags
 * \param referer  Referring URL, or NULL if none
 * \param post     POST data, or NULL for a GET request
 * \param cb       Client callback for events
 * \param pw       Pointer to client-specific data
 * \param result   Pointer to location to recieve cache handle
 * \return NSERROR_OK on success, appropriate error otherwise
 */
nserror llcache_handle_retrieve(nsurl *url, uint32_t flags,
                nsurl *referer, const llcache_post_data *post,
                llcache_handle_callback cb, void *pw,
                llcache_handle **result);
 
/**
 * Change the callback associated with a low-level cache handle
 *
 * \param handle  Handle to change callback of
 * \param cb      New callback
 * \param pw      Client data for new callback
 * \return NSERROR_OK on success, appropriate error otherwise
 */
nserror llcache_handle_change_callback(llcache_handle *handle,
                llcache_handle_callback cb, void *pw);
 
/**
 * Release a low-level cache handle
 *
 * \param handle  Handle to release
 * \return NSERROR_OK on success, appropriate error otherwise
 */
nserror llcache_handle_release(llcache_handle *handle);
 
/**
 * Clone a low-level cache handle, producing a new handle to
 * the same fetch/content.
 *
 * \param handle  Handle to clone
 * \param result  Pointer to location to receive cloned handle
 * \return NSERROR_OK on success, appropriate error otherwise
 */
nserror llcache_handle_clone(llcache_handle *handle, llcache_handle **result);
 
/**
 * Abort a low-level fetch, informing all users of this action.
 *
 * \param handle  Handle to abort
 * \return NSERROR_OK on success, appropriate error otherwise
 */
nserror llcache_handle_abort(llcache_handle *handle);
 
/**
 * Force a low-level cache handle into streaming mode
 *
 * \param handle  Handle to stream
 * \return NSERROR_OK on success, appropriate error otherwise
 */
nserror llcache_handle_force_stream(llcache_handle *handle);
 
/**
 * Invalidate cache data for a low-level cache object
 *
 * \param handle  Handle to invalidate
 * \return NSERROR_OK on success, appropriate error otherwise
 */
nserror llcache_handle_invalidate_cache_data(llcache_handle *handle);
 
/**
 * Retrieve the post-redirect URL of a low-level cache object
 *
 * \param handle  Handle to retrieve URL from
 * \return Post-redirect URL of cache object
 */
nsurl *llcache_handle_get_url(const llcache_handle *handle);
 
/**
 * Retrieve source data of a low-level cache object
 *
 * \param handle  Handle to retrieve source data from
 * \param size    Pointer to location to receive byte length of data
 * \return Pointer to source data
 */
const uint8_t *llcache_handle_get_source_data(const llcache_handle *handle,
                size_t *size);
 
/**
 * Retrieve a header value associated with a low-level cache object
 *
 * \param handle  Handle to retrieve header from
 * \param key     Header name
 * \return Header value, or NULL if header does not exist
 *
 * \todo Make the key an enumeration, to avoid needless string comparisons
 * \todo Forcing the client to parse the header value seems wrong.
 *       Better would be to return the actual value part and an array of
 *       key-value pairs for any additional parameters.
 * \todo Deal with multiple headers of the same key (e.g. Set-Cookie)
 */
const char *llcache_handle_get_header(const llcache_handle *handle,
                const char *key);
 
/**
 * Determine if the same underlying object is referenced by the given handles
 *
 * \param a  First handle
 * \param b  Second handle
 * \return True if handles reference the same object, false otherwise
 */
bool llcache_handle_references_same_object(const llcache_handle *a,
                const llcache_handle *b);
 
#endif