Index: oak-core/src/main/java/org/apache/jackrabbit/oak/plugins/segment/SegmentTracker.java
IDEA additional info:
Subsystem: com.intellij.openapi.diff.impl.patch.CharsetEP
<+>UTF-8
===================================================================
--- oak-core/src/main/java/org/apache/jackrabbit/oak/plugins/segment/SegmentTracker.java	(revision 8793e58a8be25038660596feb0b5dcef1739e954)
+++ oak-core/src/main/java/org/apache/jackrabbit/oak/plugins/segment/SegmentTracker.java	(revision e647f13a9b4c1db6cc1f2553ac348c67ce5ca747)
@@ -16,18 +16,17 @@
  */
 package org.apache.jackrabbit.oak.plugins.segment;
 
-import static com.google.common.collect.Lists.newLinkedList;
 import static com.google.common.collect.Queues.newArrayDeque;
 import static com.google.common.collect.Sets.newHashSet;
 
 import java.security.SecureRandom;
-import java.util.LinkedList;
 import java.util.Queue;
 import java.util.Set;
 import java.util.concurrent.atomic.AtomicReference;
 
 import javax.annotation.Nonnull;
 
+import org.apache.jackrabbit.oak.cache.CacheLIRS;
 import org.apache.jackrabbit.oak.plugins.blob.ReferenceCollector;
 import org.apache.jackrabbit.oak.plugins.segment.compaction.CompactionStrategy;
 import org.slf4j.Logger;
@@ -88,12 +87,12 @@
      */
     private final SegmentIdTable[] tables = new SegmentIdTable[32];
 
-    private final LinkedList<Segment> segments = newLinkedList();
-
     private long currentSize;
     
     private final StringCache stringCache;
 
+    private final CacheLIRS<SegmentId, Segment> segmentCache;
+
     public SegmentTracker(SegmentStore store, int cacheSizeMB,
             SegmentVersion version) {
         for (int i = 0; i < tables.length; i++) {
@@ -106,6 +105,10 @@
         this.compactionMap = new AtomicReference<CompactionMap>(
                 CompactionMap.EMPTY);
         stringCache = new StringCache((int) Math.min(Integer.MAX_VALUE, cacheSize));
+        segmentCache = new CacheLIRS.Builder()
+            .maximumSize((int) Math.min(Integer.MAX_VALUE, cacheSize))
+            .averageWeight(Segment.MAX_SEGMENT_SIZE/2)
+            .build();
     }
 
     public SegmentTracker(SegmentStore store, SegmentVersion version) {
@@ -128,7 +131,7 @@
      * Clear the segment cache
      */
     public synchronized void clearCache() {
-        segments.clear();
+        segmentCache.invalidateAll();
         stringCache.clear();
         currentSize = 0;
     }
@@ -154,34 +157,9 @@
         // done before synchronization to allow concurrent segment access
         // while we update the cache below
         id.setSegment(segment);
-
-        synchronized (this) {
-            long size = segment.getCacheSize();
-
-            segments.addFirst(segment);
-            currentSize += size;
-
-            log.debug("Added segment {} to tracker cache ({} bytes)",
-                    id, size);
-
-            // TODO possibly this cache could be improved
-            while (currentSize > cacheSize && segments.size() > 1) {
-                Segment last = segments.removeLast();
-                SegmentId lastId = last.getSegmentId();
-                if (last.accessed()) {
-                    segments.addFirst(last);
-                    log.debug("Segment {} was recently used, keeping in cache",
-                            lastId);
-                } else {
-                    long lastSize = last.getCacheSize();
-
-                    lastId.setSegment(null);
-                    currentSize -= lastSize;
-
-                    log.debug("Removed segment {} from tracker cache ({} bytes)",
-                            lastId, lastSize);
-                }
-            }
+        Segment previous = segmentCache.put(id, segment, segment.size());
+        if (previous != null) {
+            previous.getSegmentId().setSegment(null);
         }
     }