Cache system bug fix
- Now keep track of the number of times a file has been opened. The on-disk cache file no longer gets opened multiple times, if a file is opened multiple times.
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parent
ef7630f9a8
commit
92a9658c66
98
src/cache.c
98
src/cache.c
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@ -37,11 +37,21 @@ typedef enum {
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EMEM = -4 /**< Memory allocation failure */
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} MetaError;
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/* ---------------- External variables -----------------------*/
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int CACHE_SYSTEM_INIT = 0;
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int DATA_BLK_SZ = 0;
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int MAX_SEGBC = DEFAULT_MAX_SEGBC;
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/* ----------------- Static variables ----------------------- */
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/**
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* \brief Cache file locking
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* \details Ensure cache opening and cache closing is an atomic operation
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*/
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static pthread_mutex_t cf_lock;
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/**
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* \brief The metadata directory
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*/
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@ -111,6 +121,12 @@ static char *CacheSystem_calc_dir(const char *url)
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void CacheSystem_init(const char *path, int url_supplied)
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{
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if (pthread_mutex_init(&cf_lock, NULL) != 0) {
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fprintf(stderr,
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"CacheSystem_init(): cf_lock initialisation failed!\n");
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exit(EXIT_FAILURE);
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}
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if (url_supplied) {
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path = CacheSystem_calc_dir(path);
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}
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@ -696,16 +712,43 @@ Cache *Cache_open(const char *fn)
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return NULL;
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}
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/* Obtain the link structure memory pointer */
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Link *link = path_to_Link(fn);
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if (!link) {
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return NULL;
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}
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/*---------------- Cache_open() critical section -----------------*/
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#ifdef CACHE_LOCK_DEBUG
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fprintf(stderr, "Cache_open(): thread %lu: locking cf_lock;\n",
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pthread_self());
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#endif
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pthread_mutex_lock(&cf_lock);
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if (link->cache_opened) {
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link->cache_opened++;
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#ifdef CACHE_LOCK_DEBUG
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fprintf(stderr, "Cache_open(): thread %lu: unlocking cf_lock;\n",
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pthread_self());
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#endif
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pthread_mutex_unlock(&cf_lock);
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return link->cache_ptr;
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}
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#ifdef CACHE_LOCK_DEBUG
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fprintf(stderr, "Cache_open(): thread %lu: unlocking cf_lock;\n",
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pthread_self());
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#endif
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pthread_mutex_unlock(&cf_lock);
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/*----------------------------------------------------------------*/
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/* Create the cache in-memory data structure */
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Cache *cf = Cache_alloc();
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cf->path = strndup(fn, MAX_PATH_LEN);
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/* Associate the cache structure with a link */
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cf->link = path_to_Link(fn);
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if (!cf->link) {
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Cache_free(cf);
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return NULL;
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}
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cf->link = link;
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if (Meta_open(cf)) {
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Cache_free(cf);
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@ -750,22 +793,41 @@ cf->content_length: %ld, Data_size(fn): %ld.\n", fn, cf->content_length,
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return NULL;
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}
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cf->link->cache_opened = 1;
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/* Yup, we just created a circular loop. ;) */
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cf->link->cache_ptr = cf;
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return cf;
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}
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void Cache_close(Cache *cf)
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{
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/*--------------- Cache_close() critical section -----------------*/
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#ifdef CACHE_LOCK_DEBUG
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/* Must wait for the background download thread to stop */
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fprintf(stderr, "Cache_close(): locking bgt_lock;\n");
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pthread_mutex_lock(&cf->bgt_lock);
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fprintf(stderr, "Cache_close(): unlocking bgt_lock;\n");
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pthread_mutex_unlock(&cf->bgt_lock);
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fprintf(stderr, "Cache_close(): locking rw_lock;\n");
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pthread_mutex_lock(&cf->rw_lock);
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fprintf(stderr, "Cache_close(): unlocking rw_lock;\n");
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pthread_mutex_unlock(&cf->rw_lock);
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fprintf(stderr, "Cache_close(): thread %lu: locking cf_lock;\n",
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pthread_self());
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#endif
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pthread_mutex_lock(&cf_lock);
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cf->link->cache_opened--;
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if (cf->link->cache_opened > 0) {
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#ifdef CACHE_LOCK_DEBUG
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fprintf(stderr, "Cache_close(): thread %lu: unlocking cf_lock;\n",
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pthread_self());
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#endif
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pthread_mutex_unlock(&cf_lock);
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return;
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}
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#ifdef CACHE_LOCK_DEBUG
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fprintf(stderr, "Cache_close(): thread %lu: unlocking cf_lock;\n",
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pthread_self());
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#endif
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pthread_mutex_unlock(&cf_lock);
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/*----------------------------------------------------------------*/
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if (Meta_write(cf)) {
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fprintf(stderr, "Cache_close(): Meta_write() error.");
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@ -876,15 +938,13 @@ long Cache_read(Cache *cf, char *output_buf, off_t len, off_t offset)
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#ifdef CACHE_LOCK_DEBUG
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/* Wait for the background download thread to finish */
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fprintf(stderr, "Cache_read(): thread %lu: locking bgt_lock;\n",
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fprintf(stderr,
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"Cache_read(): thread %lu: locking and unlocking bgt_lock;\n",
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pthread_self());
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#endif
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pthread_mutex_lock(&cf->bgt_lock);
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#ifdef CACHE_LOCK_DEBUG
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fprintf(stderr, "Cache_read(): thread %lu: unlocking bgt_lock;\n",
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pthread_self());
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#endif
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pthread_mutex_unlock(&cf->bgt_lock);
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#ifdef CACHE_LOCK_DEBUG
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/* Wait for any other download thread to finish*/
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fprintf(stderr, "Cache_read(): thread %lu: locking rw_lock;\n",
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15
src/cache.h
15
src/cache.h
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@ -1,10 +1,15 @@
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#ifndef CACHE_H
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#define CACHE_H
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#include "link.h"
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#include <pthread.h>
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/**
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* \brief cache data type
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*/
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typedef struct Cache Cache;
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#include "link.h"
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/**
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* \file cache.h
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* \brief cache related structures and functions
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@ -19,9 +24,9 @@
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typedef uint8_t Seg;
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/**
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* \brief cache in-memory data structure
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* \brief cache data type in-memory data structure
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*/
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typedef struct {
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struct Cache {
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char *path; /**< the path to the file on the web server */
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Link *link; /**< the Link associated with this cache data set */
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long time; /**<the modified time of the file */
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@ -41,7 +46,7 @@ typedef struct {
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int blksz; /**<the block size of the data file */
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long segbc; /**<segment array byte count */
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Seg *seg; /**< the detail of each segment */
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} Cache;
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};
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/**
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* \brief whether the cache system is enabled
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12
src/link.c
12
src/link.c
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@ -15,7 +15,8 @@
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LinkTable *ROOT_LINK_TBL = NULL;
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int ROOT_LINK_OFFSET = 0;
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/* ----------------- Static variable ----------------------- */
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/* ----------------- Static variables ----------------------- */
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/**
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* \brief LinkTable generation priority lock
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* \details This allows LinkTable generation to be run exclusively. This
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@ -584,16 +585,13 @@ long path_download(const char *path, char *output_buf, size_t size,
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#ifdef LINK_LOCK_DEBUG
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fprintf(stderr,
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"path_download(): thread %lu: locking link_lock;\n",
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"path_download(): thread %lu: locking and unlocking link_lock;\n",
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pthread_self());
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#endif
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pthread_mutex_lock(&link_lock);
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#ifdef LINK_LOCK_DEBUG
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fprintf(stderr,
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"path_download(): thread %lu: unlocking link_lock;\n",
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pthread_self());
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#endif
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pthread_mutex_unlock(&link_lock);
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transfer_blocking(curl);
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long http_resp;
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12
src/link.h
12
src/link.h
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@ -5,6 +5,11 @@
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#include <curl/curl.h>
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/** \brief Link type */
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typedef struct Link Link;
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#include "cache.h"
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/** \brief the link type */
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typedef enum {
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LINK_HEAD = 'H',
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@ -19,11 +24,8 @@ typedef enum {
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*/
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typedef struct LinkTable LinkTable;
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/** \brief link data type */
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typedef struct Link Link;
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/**
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* \brief Link data structure
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* \brief Link type data structure
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*/
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struct Link {
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char linkname[MAX_FILENAME_LEN+1]; /**< The link name in the last level of
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@ -33,6 +35,8 @@ struct Link {
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size_t content_length; /**< CURLINFO_CONTENT_LENGTH_DOWNLOAD of the file */
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LinkTable *next_table; /**< The next LinkTable level, if it is a LINK_DIR */
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long time; /**< CURLINFO_FILETIME obtained from the server */
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int cache_opened; /**< How many times associated cache has been opened */
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Cache *cache_ptr; /**< The pointer associated with the cache file */
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};
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struct LinkTable {
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