[10.2.x] cache: apply per-volume settings on first start after clear (#13252)

src/iocore/cache/CacheProcessor.cc

@@ -70,6 +70,7 @@ void           register_cache_stats(CacheStatsBlock *rsb, const std::string &pre
 static void    cplist_update();
 static int     create_volume(int volume_number, off_t size_in_blocks, CacheType scheme, CacheVol *cp);
 static int     fillExclusiveDisks(CacheVol *cp);
+static void    cplist_apply_config_settings(CacheVol *cp, const ConfigVol *config_vol);
 
 static size_t DEFAULT_RAM_CACHE_MULTIPLIER = 10; // I.e. 10x 1MB per 1GB of disk.
 
@@ -1038,6 +1039,14 @@ cplist_reconfigure()
     }
   }
 
+  // Apply per-volume settings after all CacheVols exist; otherwise volumes created on the first
+  // start after a cache clear keep defaults and ignore the config until the next restart.
+  for (ConfigVol *config_vol = config_volumes.cp_queue.head; config_vol; config_vol = config_vol->link.next) {
+    if (config_vol->cachep) {
+      cplist_apply_config_settings(config_vol->cachep, config_vol);
+    }
+  }
+
   ts::Metrics::Gauge::store(cache_rsb.stripes, gnstripes);
 
   return 0;
@@ -1154,6 +1163,17 @@ register_cache_stats(CacheStatsBlock *rsb, const std::string &prefix)
   rsb->writer_lock_contention = ts::Metrics::Counter::createPtr(prefix + ".writer.lock_contention");
 }
 
+// Copy the per-volume tuning fields from the volume config onto the CacheVol.
+void
+cplist_apply_config_settings(CacheVol *cp, const ConfigVol *config_vol)
+{
+  cp->ramcache_enabled = config_vol->ramcache_enabled;
+  cp->avg_obj_size     = config_vol->avg_obj_size;
+  cp->fragment_size    = config_vol->fragment_size;
+  cp->ram_cache_size   = config_vol->ram_cache_size;
+  cp->ram_cache_cutoff = config_vol->ram_cache_cutoff;
+}
+
 void
 cplist_update()
 {
@@ -1165,12 +1185,7 @@ cplist_update()
     for (config_vol = config_volumes.cp_queue.head; config_vol; config_vol = config_vol->link.next) {
       if (config_vol->number == cp->vol_number) {
         if (cp->scheme == config_vol->scheme) {
-          cp->ramcache_enabled = config_vol->ramcache_enabled;
-          cp->avg_obj_size     = config_vol->avg_obj_size;
-          cp->fragment_size    = config_vol->fragment_size;
-          cp->ram_cache_size   = config_vol->ram_cache_size;
-          cp->ram_cache_cutoff = config_vol->ram_cache_cutoff;
-          config_vol->cachep   = cp;
+          config_vol->cachep = cp;
         } else {
           /* delete this volume from all the disks */
           int d_no;

tests/gold_tests/cache/cache_volume_features.replay.yaml

@@ -18,15 +18,24 @@ meta:
   version: "1.0"
 
 # This test proves that multi-parameter volume.config lines are parsed
-# correctly.  The generated volume.config lines are:
+# correctly AND that the per-volume settings actually take effect on the first
+# start after a cache clear (AuTest always starts ATS against a fresh cache).
+#  The generated volume.config lines are:
 #
-#   volume=1 scheme=http size=50% ram_cache_size=32M ram_cache_cutoff=8K
-#   volume=2 scheme=http size=50%
+#   volume=1 scheme=http size=50% ram_cache_size=32M ram_cache_cutoff=8K avg_obj_size=2000 fragment_size=1M
+#   volume=2 scheme=http size=50% ramcache=false
 #
 # All 5 key=value pairs on line 1 must be parsed from the single line.
 # If the inner loop's "tmp = line_end" advancement were broken (as claimed
 # in a PR review), only "volume=1" would be parsed, scheme and size would
-# be missing, and the volume would be rejected -- disabling the cache.
+# be missing, and the volume would be rejected -- disabling the cache, and the
+# per-volume settings are verified via the metric_checks below:
+#   - Volume 1 (ram_cache_size: 32M, single 128MB stripe) -> ram_cache total_bytes == 32MB
+#   - Volume 1 (avg_obj_size: 2000)                        -> direntries.total == 66424
+#   - Volume 2 (ramcache: false)                          -> ram_cache total_bytes == 0
+# These exercise two distinct downstream paths (the RAM cache sizing in
+# cacheInitialized() and the directory sizing in the StripeSM constructor). On a
+# build that ignores per-volume settings on first start, none of them match.
 autest:
   description: "Test cache volume features: per-volume RAM cache and @volume= directive"
 
@@ -57,10 +66,13 @@ autest:
         size: "50%"
         ram_cache_size: "32M"
         ram_cache_cutoff: "8K"
+        avg_obj_size: 2000
+        fragment_size: 1M
       # Volume 2 — simple line, no extra params
       - volume: 2
         scheme: "http"
         size: "50%"
+        ramcache: false
 
     log_validation:
       traffic_out:

tests/gold_tests/cache/cache_volume_features.test.py

@@ -16,7 +16,8 @@
 
 Test.Summary = '''
 Comprehensive test suite for cache volume features:
-- Per-volume RAM cache configuration (ram_cache_size, ram_cache_cutoff)
+- Per-volume RAM cache configuration (ram_cache, ram_cache_size, ram_cache_cutoff)
+- Per-volume settings take effect on the first start after a cache clear
 - @volume= directive in remap.config for volume selection
 - Integration between both features
 '''