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).

1 files changed, 27 insertions, 5 deletions

diff --git a/src/core/ngx_file.c b/src/core/ngx_file.c
index 8359c0fee..b7dd4bca3 100644
--- 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, ngx_path_t *path, ngx_pool_t *pool,
     }
 #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, ngx_path_t *path, ngx_pool_t *pool,
     }
 
     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);