OAK-12047 - CachingSegmentArchiveReader#readSegment should check if archive contains segment before looking up in the PersistentCache (#2672)

Author: nfsantos

oak-segment-tar/src/main/java/org/apache/jackrabbit/oak/segment/spi/persistence/persistentcache/CachingSegmentArchiveReader.java

@@ -46,7 +46,11 @@ public CachingSegmentArchiveReader(
     @Override
     @Nullable
     public Buffer readSegment(long msb, long lsb) throws IOException {
-        return persistentCache.readSegment(msb, lsb, () -> delegate.readSegment(msb, lsb));
+        if (delegate.containsSegment(msb, lsb)) {
+            return persistentCache.readSegment(msb, lsb, () -> delegate.readSegment(msb, lsb));
+        } else {
+            return null;
+        }
     }
 
     @Override

oak-segment-tar/src/test/java/org/apache/jackrabbit/oak/segment/spi/persistence/persistentcache/CachingSegmentArchiveReaderTest.java

@@ -79,6 +79,13 @@ public void containsSegmentDoesNotUsePersistentDiskCache() throws IOException {
         SegmentArchiveReader tar2 = cachingArchiveManager.open(archive2Name);
         assertEquals(Buffer.wrap(data2), tar2.readSegment(msb2, lsb2));
 
+        // Both segments are cached
+        // Now check that each tar file only contains its own segment, that is, when searching for a segment that is
+        // not in the archive, it should not be retrieved from the cache
+        assertNull(tar1.readSegment(msb2, lsb2));
+        assertNull(tar2.readSegment(msb1, lsb1));
+
+        // Check that contains also respects archive boundaries
         assertTrue(tar1.containsSegment(msb1, lsb1));
         assertFalse(tar1.containsSegment(msb2, lsb2));
         assertFalse(tar2.containsSegment(msb1, lsb1));