static time_t
ngx_http_file_cache_expire(ngx_http_file_cache_t *cache)
{
u_char *name, *p;
size_t len;
time_t now, wait;
ngx_path_t *path;
ngx_queue_t *q;
ngx_http_file_cache_node_t *fcn;
u_char key[2 * NGX_HTTP_CACHE_KEY_LEN];
ngx_log_debug0(NGX_LOG_DEBUG_HTTP, ngx_cycle->log, 0,
"http file cache expire");
path = cache->path;
len = path->name.len + 1 + path->len + 2 * NGX_HTTP_CACHE_KEY_LEN;
name = ngx_alloc(len + 1, ngx_cycle->log);
if (name == NULL) {
return 10;
}
ngx_memcpy(name, path->name.data, path->name.len);
now = ngx_time();
ngx_shmtx_lock(&cache->shpool->mutex);
for ( ;; ) {
if (ngx_queue_empty(&cache->sh->queue)) {
wait = 10;
break;
}
q = ngx_queue_last(&cache->sh->queue);
fcn = ngx_queue_data(q, ngx_http_file_cache_node_t, queue);
wait = fcn->expire - now;
if (wait > 0) {
wait = wait > 10 ? 10 : wait;
break;
}
ngx_log_debug6(NGX_LOG_DEBUG_HTTP, ngx_cycle->log, 0,
"http file cache expire: #%d %d %02xd%02xd%02xd%02xd",
fcn->count, fcn->exists,
fcn->key[0], fcn->key[1], fcn->key[2], fcn->key[3]);
if (fcn->count) {
p = ngx_hex_dump(key, (u_char *) &fcn->node.key,
sizeof(ngx_rbtree_key_t));
len = NGX_HTTP_CACHE_KEY_LEN - sizeof(ngx_rbtree_key_t);
(void) ngx_hex_dump(p, fcn->key, len);
/*
* abnormally exited workers may leave locked cache entries,
* and although it may be safe to remove them completely,
* we prefer to remove them from inactive queue and rbtree
* only, and to allow other leaks
*/
ngx_queue_remove(q);
ngx_rbtree_delete(&cache->sh->rbtree, &fcn->node);
ngx_log_error(NGX_LOG_ALERT, ngx_cycle->log, 0,
"ignore long locked inactive cache entry %*s, count:%d",
2 * NGX_HTTP_CACHE_KEY_LEN, key, fcn->count);
continue;
}
if (!fcn->exists) {
ngx_queue_remove(q);
ngx_rbtree_delete(&cache->sh->rbtree, &fcn->node);
ngx_slab_free_locked(cache->shpool, fcn);
continue;
}
ngx_http_file_cache_delete(cache, q, name);
}
ngx_shmtx_unlock(&cache->shpool->mutex);
ngx_free(name);
return wait;
}
/*
ngx_http_file_cache_expire，使用了LRU，也就是队列最尾端保存的是最长时间没有被使用的,并且这个函数返回的就是一个wait值
*/
static time_t
ngx_http_file_cache_expire(ngx_http_file_cache_t *cache)
{
u_char *name, *p;
size_t len;
time_t now, wait;
ngx_path_t *path;
ngx_queue_t *q;
ngx_http_file_cache_node_t *fcn;
u_char key[2 * NGX_HTTP_CACHE_KEY_LEN];
ngx_log_debug0(NGX_LOG_DEBUG_HTTP, ngx_cycle->log, 0,
"http file cache expire");
path = cache->path;
len = path->name.len + 1 + path->len + 2 * NGX_HTTP_CACHE_KEY_LEN; //
name = ngx_alloc(len + 1, ngx_cycle->log);
if (name == NULL) {
return 10;
}
// 拷贝路径名 -- cache存放的目录，不包括子目录
ngx_memcpy(name, path->name.data, path->name.len);
now = ngx_time();
ngx_shmtx_lock(&cache->shpool->mutex); // 共享内存区上锁
for ( ;; ) {
// 队列空，直接返回
if (ngx_queue_empty(&cache->sh->queue)) {
wait = 10;
break;
}
// 在队列的尾部取出一个节点，检查是否已经过期
q = ngx_queue_last(&cache->sh->queue);
fcn = ngx_queue_data(q, ngx_http_file_cache_node_t, queue);
wait = fcn->expire - now;
if (wait > 0) { // wait大于0说明未过期
wait = wait > 10 ? 10 : wait;
break;
}
// 此节点已经过期
ngx_log_debug6(NGX_LOG_DEBUG_HTTP, ngx_cycle->log, 0,
"http file cache expire: #%d %d %02xd%02xd%02xd%02xd",
fcn->count, fcn->exists,
fcn->key[0], fcn->key[1], fcn->key[2], fcn->key[3]);
if (fcn->count == 0) {
ngx_http_file_cache_delete(cache, q, name);
continue;
}
if (fcn->deleting) {
wait = 1;
break;
}
// 转换文件名到acsii格式
p = ngx_hex_dump(key, (u_char *) &fcn->node.key,
sizeof(ngx_rbtree_key_t));
len = NGX_HTTP_CACHE_KEY_LEN - sizeof(ngx_rbtree_key_t);
(void) ngx_hex_dump(p, fcn->key, len);
/*
* abnormally exited workers may leave locked cache entries,
* and although it may be safe to remove them completely,
* we prefer to just move them to the top of the inactive queue
*/
// 将节点放入队列的头部
ngx_queue_remove(q);
// 重新计算过期时间
fcn->expire = ngx_time() + cache->inactive;
ngx_queue_insert_head(&cache->sh->queue, &fcn->queue);
ngx_log_error(NGX_LOG_ALERT, ngx_cycle->log, 0,
"ignore long locked inactive cache entry %*s, count:%d",
2 * NGX_HTTP_CACHE_KEY_LEN, key, fcn->count);
}
ngx_shmtx_unlock(&cache->shpool->mutex);
ngx_free(name);
return wait;
}
static time_t
ngx_http_file_cache_forced_expire(ngx_http_file_cache_t *cache)
{
u_char *name;
size_t len;
time_t wait;
ngx_uint_t tries;
ngx_path_t *path;
ngx_queue_t *q;
ngx_http_file_cache_node_t *fcn;
ngx_log_debug0(NGX_LOG_DEBUG_HTTP, ngx_cycle->log, 0,
"http file cache forced expire");
path = cache->path;
len = path->name.len + 1 + path->len + 2 * NGX_HTTP_CACHE_KEY_LEN;
name = ngx_alloc(len + 1, ngx_cycle->log);
if (name == NULL) {
return 10;
}
ngx_memcpy(name, path->name.data, path->name.len);
wait = 10;
tries = 0;
ngx_shmtx_lock(&cache->shpool->mutex);
for (q = ngx_queue_last(&cache->sh->queue);
q != ngx_queue_sentinel(&cache->sh->queue);
q = ngx_queue_prev(q))
{
fcn = ngx_queue_data(q, ngx_http_file_cache_node_t, queue);
ngx_log_debug6(NGX_LOG_DEBUG_HTTP, ngx_cycle->log, 0,
"http file cache forced expire: #%d %d %02xd%02xd%02xd%02xd",
fcn->count, fcn->exists,
fcn->key[0], fcn->key[1], fcn->key[2], fcn->key[3]);
if (fcn->count) {
if (tries++ < 20) {
continue;
}
wait = 1;
break;
}
if (!fcn->exists) {
ngx_queue_remove(q);
ngx_rbtree_delete(&cache->sh->rbtree, &fcn->node);
ngx_slab_free_locked(cache->shpool, fcn);
break;
}
ngx_http_file_cache_delete(cache, q, name);
break;
}
ngx_shmtx_unlock(&cache->shpool->mutex);
ngx_free(name);
return wait;
}
/*
* 强制删除一个cache节点
*/
static time_t
ngx_http_file_cache_forced_expire(ngx_http_file_cache_t *cache)
{
u_char *name;
size_t len;
time_t wait;
ngx_uint_t tries;
ngx_path_t *path;
ngx_queue_t *q;
ngx_http_file_cache_node_t *fcn;
ngx_log_debug0(NGX_LOG_DEBUG_HTTP, ngx_cycle->log, 0,
"http file cache forced expire");
path = cache->path;
len = path->name.len + 1 + path->len + 2 * NGX_HTTP_CACHE_KEY_LEN; // 文件的完整路径
// len + 1: 文件名包括"\0"
name = ngx_alloc(len + 1, ngx_cycle->log);
if (name == NULL) {
return 10;
}
ngx_memcpy(name, path->name.data, path->name.len);
wait = 10;
tries = 20;
ngx_shmtx_lock(&cache->shpool->mutex);
for (q = ngx_queue_last(&cache->sh->queue);
q != ngx_queue_sentinel(&cache->sh->queue);
q = ngx_queue_prev(q))
{
fcn = ngx_queue_data(q, ngx_http_file_cache_node_t, queue);
ngx_log_debug6(NGX_LOG_DEBUG_HTTP, ngx_cycle->log, 0,
"http file cache forced expire: #%d %d %02xd%02xd%02xd%02xd",
fcn->count, fcn->exists,
fcn->key[0], fcn->key[1], fcn->key[2], fcn->key[3]);
// cache节点引用计数等于0时，直接删除文件
if (fcn->count == 0) {
ngx_http_file_cache_delete(cache, q, name);
wait = 0;
} else {
// 尝试20次
if (--tries) {
continue;
}
wait = 1;
}
break;
}
ngx_shmtx_unlock(&cache->shpool->mutex);
ngx_free(name);
return wait;
}
