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06a99fe36f
databases. - Make nsswitch support caching. Submitted by: Michael Bushkov <bushman__at__rsu.ru> Sponsored by: Google Summer of Code 2005
282 lines
8.2 KiB
C
282 lines
8.2 KiB
C
/*-
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* Copyright (c) 2005 Michael Bushkov <bushman@rsu.ru>
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* All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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*
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* THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
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* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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*
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* $FreeBSD$
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*/
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#ifndef __CACHED_CACHELIB_H__
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#define __CACHED_CACHELIB_H__
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#include <sys/queue.h>
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#include <sys/time.h>
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#include <stdlib.h>
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#include "hashtable.h"
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#include "cacheplcs.h"
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enum cache_entry_t {
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CET_COMMON = 0, /* cache item is atomic */
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CET_MULTIPART /* cache item is formed part by part */
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};
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enum cache_transformation_t {
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CTT_FLUSH = 0, /* flush the cache - delete all obsolete items */
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CTT_CLEAR = 1 /* delete all items in the cache */
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};
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/* cache deletion policy type enum */
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enum cache_policy_t {
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CPT_FIFO = 0, /* first-in first-out */
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CPT_LRU = 1, /* least recently used */
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CPT_LFU = 2 /* least frequently used */
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};
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/* multipart sessions can be used for reading and writing */
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enum cache_mp_session_t {
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CMPT_READ_SESSION,
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CMPT_WRITE_SESSION
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};
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/*
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* When doing partial transformations of entries (which are applied for
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* elements with keys, that contain specified buffer in its left or
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* right part), this enum will show the needed position of the key part.
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*/
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enum part_position_t {
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KPPT_LEFT,
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KPPT_RIGHT
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};
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/* num_levels attribute is obsolete, i think - user can always emulate it
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* by using one entry.
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* get_time_func is needed to have the clocks-independent counter
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*/
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struct cache_params
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{
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void (*get_time_func)(struct timeval *);
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};
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/*
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* base structure - normal_cache_entry_params and multipart_cache_entry_params
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* are "inherited" from it
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*/
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struct cache_entry_params
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{
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enum cache_entry_t entry_type;
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char *entry_name;
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};
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/* params, used for most entries */
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struct common_cache_entry_params
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{
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/* inherited fields */
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enum cache_entry_t entry_type;
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/* unique fields */
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char *entry_name;
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size_t cache_entries_size;
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size_t max_elemsize; /* if 0 then no check is made */
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size_t satisf_elemsize; /* if entry size is exceeded,
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* this number of elements will be left,
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* others will be deleted */
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struct timeval max_lifetime; /* if 0 then no check is made */
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enum cache_policy_t policy; /* policy used for transformations */
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};
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/* params, used for multipart entries */
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struct mp_cache_entry_params
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{
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/* inherited fields */
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enum cache_entry_t entry_type;
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char *entry_name;
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/* unique fields */
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size_t max_elemsize; /* if 0 then no check is made */
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size_t max_sessions; /* maximum number of active sessions */
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struct timeval max_lifetime; /* maximum elements lifetime */
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};
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struct cache_ht_item_data_
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{
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/* key is the bytes sequence only - not the null-terminated string */
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char *key;
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size_t key_size;
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char *value;
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size_t value_size;
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struct cache_policy_item_ *fifo_policy_item;
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};
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struct cache_ht_item_
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{
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HASHTABLE_ENTRY_HEAD(ht_item_, struct cache_ht_item_data_) data;
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};
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struct cache_entry_
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{
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char *name;
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struct cache_entry_params *params;
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};
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struct cache_common_entry_
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{
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char *name;
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struct cache_entry_params *params;
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struct common_cache_entry_params common_params;
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HASHTABLE_HEAD(cache_ht_, cache_ht_item_) items;
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size_t items_size;
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/*
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* Entry always has the FIFO policy, that is used to eliminate old
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* elements (the ones, with lifetime more than max_lifetime). Besides,
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* user can specify another policy to be applied, when there are too
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* many elements in the entry. So policies_size can be 1 or 2.
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*/
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struct cache_policy_ **policies;
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size_t policies_size;
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void (*get_time_func)(struct timeval *);
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};
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struct cache_mp_data_item_ {
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char *value;
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size_t value_size;
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TAILQ_ENTRY(cache_mp_data_item_) entries;
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};
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struct cache_mp_write_session_
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{
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struct cache_mp_entry_ *parent_entry;
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/*
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* All items are accumulated in this queue. When the session is
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* committed, they all will be copied to the multipart entry.
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*/
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TAILQ_HEAD(cache_mp_data_item_head, cache_mp_data_item_) items;
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size_t items_size;
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TAILQ_ENTRY(cache_mp_write_session_) entries;
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};
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struct cache_mp_read_session_
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{
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struct cache_mp_entry_ *parent_entry;
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struct cache_mp_data_item_ *current_item;
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TAILQ_ENTRY(cache_mp_read_session_) entries;
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};
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struct cache_mp_entry_
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{
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char *name;
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struct cache_entry_params *params;
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struct mp_cache_entry_params mp_params;
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/* All opened write sessions */
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TAILQ_HEAD(write_sessions_head, cache_mp_write_session_) ws_head;
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size_t ws_size;
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/* All opened read sessions */
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TAILQ_HEAD(read_sessions_head, cache_mp_read_session_) rs_head;
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size_t rs_size;
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/*
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* completed_write_session is the committed write sessions. All read
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* sessions use data from it. If the completed_write_session is out of
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* date, but still in use by some of the read sessions, the newly
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* committed write session is stored in the pending_write_session.
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* In such a case, completed_write_session will be substituted with
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* pending_write_session as soon as it won't be used by any of
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* the read sessions.
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*/
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struct cache_mp_write_session_ *completed_write_session;
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struct cache_mp_write_session_ *pending_write_session;
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struct timeval creation_time;
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struct timeval last_request_time;
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void (*get_time_func)(struct timeval *);
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};
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struct cache_
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{
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struct cache_params params;
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struct cache_entry_ **entries;
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size_t entries_capacity;
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size_t entries_size;
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};
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/* simple abstractions - for not to write "struct" every time */
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typedef struct cache_ *cache;
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typedef struct cache_entry_ *cache_entry;
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typedef struct cache_mp_write_session_ *cache_mp_write_session;
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typedef struct cache_mp_read_session_ *cache_mp_read_session;
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#define INVALID_CACHE (NULL)
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#define INVALID_CACHE_ENTRY (NULL)
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#define INVALID_CACHE_MP_WRITE_SESSION (NULL)
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#define INVALID_CACHE_MP_READ_SESSION (NULL)
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/*
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* NOTE: all cache operations are thread-unsafe. You must ensure thread-safety
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* externally, by yourself.
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*/
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/* cache initialization/destruction routines */
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extern cache init_cache(struct cache_params const *);
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extern void destroy_cache(cache);
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/* cache entries manipulation routines */
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extern int register_cache_entry(cache, struct cache_entry_params const *);
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extern int unregister_cache_entry(cache, const char *);
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extern cache_entry find_cache_entry(cache, const char *);
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/* read/write operations used on common entries */
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extern int cache_read(cache_entry, const char *, size_t, char *, size_t *);
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extern int cache_write(cache_entry, const char *, size_t, char const *, size_t);
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/* read/write operations used on multipart entries */
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extern cache_mp_write_session open_cache_mp_write_session(cache_entry);
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extern int cache_mp_write(cache_mp_write_session, char *, size_t);
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extern void abandon_cache_mp_write_session(cache_mp_write_session);
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extern void close_cache_mp_write_session(cache_mp_write_session);
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extern cache_mp_read_session open_cache_mp_read_session(cache_entry);
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extern int cache_mp_read(cache_mp_read_session, char *, size_t *);
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extern void close_cache_mp_read_session(cache_mp_read_session);
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/* transformation routines */
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extern int transform_cache_entry(cache_entry, enum cache_transformation_t);
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extern int transform_cache_entry_part(cache_entry, enum cache_transformation_t,
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const char *, size_t, enum part_position_t);
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#endif
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