# HG changeset patch
# User Maxim Dounin <mdounin@mdounin.ru>
# Date 1478182229 -10800
# Node ID 1a917932db963e7ecf4d786cc02bd54bd4548b88
# Parent  93b294c5d5812269402b382f3ac0374f0bd3397a
Cache: prefix-based temporary files.

On Linux, the rename syscall can be slow due to a global file system lock,
acquired for the entire rename operation, unless both old and new files are
in the same directory.  To address this temporary files are now created
in the same directory as the expected resulting cache file when using the
"use_temp_path=off" parameter.

This change mostly reverts 99639bfdfa2a and 3281de8142f5, restoring the
behaviour as of a9138c35120d (with minor changes).

diff --git a/src/core/ngx_file.c b/src/core/ngx_file.c
--- a/src/core/ngx_file.c
+++ b/src/core/ngx_file.c
@@ -141,12 +141,27 @@ ngx_int_t
 ngx_create_temp_file(ngx_file_t *file, ngx_path_t *path, ngx_pool_t *pool,
     ngx_uint_t persistent, ngx_uint_t clean, ngx_uint_t access)
 {
+    size_t                    levels;
+    u_char                   *p;
     uint32_t                  n;
     ngx_err_t                 err;
+    ngx_str_t                 name;
+    ngx_uint_t                prefix;
     ngx_pool_cleanup_t       *cln;
     ngx_pool_cleanup_file_t  *clnf;
 
-    file->name.len = path->name.len + 1 + path->len + 10;
+    if (file->name.len) {
+        name = file->name;
+        levels = 0;
+        prefix = 1;
+
+    } else {
+        name = path->name;
+        levels = path->len;
+        prefix = 0;
+    }
+
+    file->name.len = name.len + 1 + levels + 10;
 
     file->name.data = ngx_pnalloc(pool, file->name.len + 1);
     if (file->name.data == NULL) {
@@ -159,7 +174,13 @@ ngx_create_temp_file(ngx_file_t *file, n
     }
 #endif
 
-    ngx_memcpy(file->name.data, path->name.data, path->name.len);
+    p = ngx_cpymem(file->name.data, name.data, name.len);
+
+    if (prefix) {
+        *p = '.';
+    }
+
+    p += 1 + levels;
 
     n = (uint32_t) ngx_next_temp_number(0);
 
@@ -169,10 +190,11 @@ ngx_create_temp_file(ngx_file_t *file, n
     }
 
     for ( ;; ) {
-        (void) ngx_sprintf(file->name.data + path->name.len + 1 + path->len,
-                           "%010uD%Z", n);
+        (void) ngx_sprintf(p, "%010uD%Z", n);
 
-        ngx_create_hashed_filename(path, file->name.data, file->name.len);
+        if (!prefix) {
+            ngx_create_hashed_filename(path, file->name.data, file->name.len);
+        }
 
         ngx_log_debug1(NGX_LOG_DEBUG_CORE, file->log, 0,
                        "hashed path: %s", file->name.data);
diff --git a/src/http/ngx_http_cache.h b/src/http/ngx_http_cache.h
--- a/src/http/ngx_http_cache.h
+++ b/src/http/ngx_http_cache.h
@@ -151,7 +151,6 @@ struct ngx_http_file_cache_s {
     ngx_slab_pool_t                 *shpool;
 
     ngx_path_t                      *path;
-    ngx_path_t                      *temp_path;
 
     off_t                            max_size;
     size_t                           bsize;
@@ -171,6 +170,9 @@ struct ngx_http_file_cache_s {
     ngx_msec_t                       manager_threshold;
 
     ngx_shm_zone_t                  *shm_zone;
+
+    ngx_uint_t                       use_temp_path;
+                                     /* unsigned use_temp_path:1 */
 };
 
 
diff --git a/src/http/ngx_http_file_cache.c b/src/http/ngx_http_file_cache.c
--- a/src/http/ngx_http_file_cache.c
+++ b/src/http/ngx_http_file_cache.c
@@ -2112,6 +2112,17 @@ ngx_http_file_cache_add_file(ngx_tree_ct
         return NGX_ERROR;
     }
 
+    /*
+     * Temporary files in cache have a suffix consisting of a dot
+     * followed by 10 digits.
+     */
+
+    if (name->len >= 2 * NGX_HTTP_CACHE_KEY_LEN + 1 + 10
+        && name->data[name->len - 10 - 1] == '.')
+    {
+        return NGX_OK;
+    }
+
     if (ctx->size < (off_t) sizeof(ngx_http_file_cache_header_t)) {
         ngx_log_error(NGX_LOG_CRIT, ctx->log, 0,
                       "cache file \"%s\" is too small", name->data);
@@ -2256,7 +2267,6 @@ ngx_http_file_cache_set_slot(ngx_conf_t 
     off_t                   max_size;
     u_char                 *last, *p;
     time_t                  inactive;
-    size_t                  len;
     ssize_t                 size;
     ngx_str_t               s, name, *value;
     ngx_int_t               loader_files, manager_files;
@@ -2529,37 +2539,6 @@ ngx_http_file_cache_set_slot(ngx_conf_t 
         return NGX_CONF_ERROR;
     }
 
-    if (!use_temp_path) {
-        cache->temp_path = ngx_pcalloc(cf->pool, sizeof(ngx_path_t));
-        if (cache->temp_path == NULL) {
-            return NGX_CONF_ERROR;
-        }
-
-        len = cache->path->name.len + sizeof("/temp") - 1;
-
-        p = ngx_pnalloc(cf->pool, len + 1);
-        if (p == NULL) {
-            return NGX_CONF_ERROR;
-        }
-
-        cache->temp_path->name.len = len;
-        cache->temp_path->name.data = p;
-
-        p = ngx_cpymem(p, cache->path->name.data, cache->path->name.len);
-        ngx_memcpy(p, "/temp", sizeof("/temp"));
-
-        ngx_memcpy(&cache->temp_path->level, &cache->path->level,
-                   NGX_MAX_PATH_LEVEL * sizeof(size_t));
-
-        cache->temp_path->len = cache->path->len;
-        cache->temp_path->conf_file = cf->conf_file->file.name.data;
-        cache->temp_path->line = cf->conf_file->line;
-
-        if (ngx_add_path(cf, &cache->temp_path) != NGX_OK) {
-            return NGX_CONF_ERROR;
-        }
-    }
-
     cache->shm_zone = ngx_shared_memory_add(cf, &name, size, cmd->post);
     if (cache->shm_zone == NULL) {
         return NGX_CONF_ERROR;
@@ -2575,6 +2554,8 @@ ngx_http_file_cache_set_slot(ngx_conf_t 
     cache->shm_zone->init = ngx_http_file_cache_init;
     cache->shm_zone->data = cache;
 
+    cache->use_temp_path = use_temp_path;
+
     cache->inactive = inactive;
     cache->max_size = max_size;
 
diff --git a/src/http/ngx_http_upstream.c b/src/http/ngx_http_upstream.c
--- a/src/http/ngx_http_upstream.c
+++ b/src/http/ngx_http_upstream.c
@@ -2997,8 +2997,9 @@ ngx_http_upstream_send_response(ngx_http
         p->temp_file->persistent = 1;
 
 #if (NGX_HTTP_CACHE)
-        if (r->cache && r->cache->file_cache->temp_path) {
-            p->temp_file->path = r->cache->file_cache->temp_path;
+        if (r->cache && !r->cache->file_cache->use_temp_path) {
+            p->temp_file->path = r->cache->file_cache->path;
+            p->temp_file->file.name = r->cache->file.name;
         }
 #endif