From 3a76ffc9464eafc073b69fbe56b179c4c3077444 Mon Sep 17 00:00:00 2001
From: Tanguy Leroux <tlrx.dev@gmail.com>
Date: Fri, 15 Jan 2021 13:42:28 +0100
Subject: [PATCH] Add assertion message when decrementing cache file (#67561)
 (#67567)

---
 .../index/store/cache/CacheFile.java           | 18 ++++++++++++++++--
 1 file changed, 16 insertions(+), 2 deletions(-)

diff --git a/x-pack/plugin/searchable-snapshots/src/main/java/org/elasticsearch/index/store/cache/CacheFile.java b/x-pack/plugin/searchable-snapshots/src/main/java/org/elasticsearch/index/store/cache/CacheFile.java
index 5793f4d33c5b3..6d84fd72d23f2 100644
--- a/x-pack/plugin/searchable-snapshots/src/main/java/org/elasticsearch/index/store/cache/CacheFile.java
+++ b/x-pack/plugin/searchable-snapshots/src/main/java/org/elasticsearch/index/store/cache/CacheFile.java
@@ -228,7 +228,21 @@ private boolean assertNoPendingListeners() {
 
     private void decrementRefCount() {
         final boolean released = refCounter.decRef();
-        assert released == false || (evicted.get() && Files.notExists(file));
+        assert assertRefCounted(released);
+    }
+
+    private boolean assertRefCounted(boolean isReleased) {
+        final boolean isEvicted = evicted.get();
+        final boolean notExists = Files.notExists(file);
+        assert isReleased == false || (isEvicted && notExists) : "fully released cache file should be deleted from disk but got ["
+            + "released="
+            + isReleased
+            + ", evicted="
+            + isEvicted
+            + ", file not exists="
+            + notExists
+            + ']';
+        return true;
     }
 
     /**
@@ -487,7 +501,7 @@ public SortedSet<Tuple<Long, Long>> fsync() throws IOException {
                     }
                 }
             } finally {
-                refCounter.decRef();
+                decrementRefCount();
             }
         } else {
             assert evicted.get();