assert+comment

Author: tlrx

x-pack/plugin/blob-cache/src/main/java/org/elasticsearch/blobcache/shared/SharedBlobCacheService.java

@@ -1006,6 +1006,8 @@ public int populateAndRead(
             final RangeAvailableHandler reader,
             final RangeMissingHandler writer
         ) throws Exception {
+            // some cache files can grow after being created, so rangeToWrite can be larger than the initial {@code length}
+            assert rangeToWrite.start() >= 0 : rangeToWrite;
             assert assertOffsetsWithinFileLength(rangeToRead.start(), rangeToRead.length(), length);
             // We are interested in the total time that the system spends when fetching a result (including time spent queuing), so we start
             // our measurement here.