From 0a683fdd9313b9796bf39442fd117beaa63a7157 Mon Sep 17 00:00:00 2001
From: Maxim Dounin <mdounin@mdounin.ru>
Date: Mon, 22 Jun 2020 18:03:00 +0300
Subject: Cache: introduced min_free cache clearing.

Clearing cache based on free space left on a file system is
expected to allow better disk utilization in some cases, notably
when disk space might be also used for something other than nginx
cache (including nginx own temporary files) and while loading
cache (when cache size might be inaccurate for a while, effectively
disabling max_size cache clearing).

Based on a patch by Adam Bambuch.
---
 src/http/ngx_http_file_cache.c | 43 +++++++++++++++++++++++++++++++++++++++---
 1 file changed, 40 insertions(+), 3 deletions(-)

(limited to 'src/http/ngx_http_file_cache.c')

diff --git a/src/http/ngx_http_file_cache.c b/src/http/ngx_http_file_cache.c
index ecdf11e28..e985f27b1 100644
--- a/src/http/ngx_http_file_cache.c
+++ b/src/http/ngx_http_file_cache.c
@@ -1959,7 +1959,7 @@ ngx_http_file_cache_manager(void *data)
 {
     ngx_http_file_cache_t  *cache = data;
 
-    off_t       size;
+    off_t       size, free;
     time_t      wait;
     ngx_msec_t  elapsed, next;
     ngx_uint_t  count, watermark;
@@ -1988,7 +1988,19 @@ ngx_http_file_cache_manager(void *data)
                        size, count, (ngx_int_t) watermark);
 
         if (size < cache->max_size && count < watermark) {
-            break;
+
+            if (!cache->min_free) {
+                break;
+            }
+
+            free = ngx_fs_available(cache->path->name.data);
+
+            ngx_log_debug1(NGX_LOG_DEBUG_HTTP, ngx_cycle->log, 0,
+                           "http file cache free: %O", free);
+
+            if (free > cache->min_free) {
+                break;
+            }
         }
 
         wait = ngx_http_file_cache_forced_expire(cache);
@@ -2304,7 +2316,7 @@ ngx_http_file_cache_set_slot(ngx_conf_t *cf, ngx_command_t *cmd, void *conf)
 {
     char  *confp = conf;
 
-    off_t                   max_size;
+    off_t                   max_size, min_free;
     u_char                 *last, *p;
     time_t                  inactive;
     ssize_t                 size;
@@ -2341,6 +2353,7 @@ ngx_http_file_cache_set_slot(ngx_conf_t *cf, ngx_command_t *cmd, void *conf)
     name.len = 0;
     size = 0;
     max_size = NGX_MAX_OFF_T_VALUE;
+    min_free = 0;
 
     value = cf->args->elts;
 
@@ -2476,6 +2489,29 @@ ngx_http_file_cache_set_slot(ngx_conf_t *cf, ngx_command_t *cmd, void *conf)
             continue;
         }
 
+        if (ngx_strncmp(value[i].data, "min_free=", 9) == 0) {
+
+#if (NGX_WIN32 || NGX_HAVE_STATFS || NGX_HAVE_STATVFS)
+
+            s.len = value[i].len - 9;
+            s.data = value[i].data + 9;
+
+            min_free = ngx_parse_offset(&s);
+            if (min_free < 0) {
+                ngx_conf_log_error(NGX_LOG_EMERG, cf, 0,
+                                   "invalid min_free value \"%V\"", &value[i]);
+                return NGX_CONF_ERROR;
+            }
+
+#else
+            ngx_conf_log_error(NGX_LOG_WARN, cf, 0,
+                               "min_free is not supported "
+                               "on this platform, ignored");
+#endif
+
+            continue;
+        }
+
         if (ngx_strncmp(value[i].data, "loader_files=", 13) == 0) {
 
             loader_files = ngx_atoi(value[i].data + 13, value[i].len - 13);
@@ -2607,6 +2643,7 @@ ngx_http_file_cache_set_slot(ngx_conf_t *cf, ngx_command_t *cmd, void *conf)
 
     cache->inactive = inactive;
     cache->max_size = max_size;
+    cache->min_free = min_free;
 
     caches = (ngx_array_t *) (confp + cmd->offset);
 
-- 
cgit