LIRS cache: make the non-resident queue size configurable

h2/src/main/org/h2/mvstore/MVStore.java

@@ -322,15 +322,11 @@ public class MVStore {
         o = config.get("cacheSize");
         int mb = o == null ? 16 : (Integer) o;
         if (mb > 0) {
-            long maxMemoryBytes = mb * 1024L * 1024L;
-            int segmentCount = 16;
-            int stackMoveDistance = 8;
-            cache = new CacheLongKeyLIRS<Page>(
-                    maxMemoryBytes,
-                    segmentCount, stackMoveDistance);
-            cacheChunkRef = new CacheLongKeyLIRS<PageChildren>(
-                    maxMemoryBytes / 4,
-                    segmentCount, stackMoveDistance);
+            CacheLongKeyLIRS.Config cc = new CacheLongKeyLIRS.Config();
+            cc.maxMemory = mb * 1024L * 1024L;
+            cache = new CacheLongKeyLIRS<Page>(cc);
+            cc.maxMemory /= 4;
+            cacheChunkRef = new CacheLongKeyLIRS<PageChildren>(cc);
         }
         o = config.get("autoCommitBufferSize");
         int kb = o == null ? 1024 : (Integer) o;

h2/src/main/org/h2/mvstore/cache/CacheLongKeyLIRS.java

@@ -55,35 +55,23 @@ public class CacheLongKeyLIRS<V> {
     private final int segmentShift;
     private final int segmentMask;
     private final int stackMoveDistance;
-
-    /**
-     * Create a new cache with the given number of entries, and the default
-     * settings (16 segments, and stack move distance of 8.
-     *
-     * @param maxMemory the maximum memory to use (1 or larger)
-     */
-    public CacheLongKeyLIRS(long maxMemory) {
-        this(maxMemory, 16, 8);
-    }
+    private final double nonResidentQueueSize;
 
     /**
      * Create a new cache with the given memory size.
      *
-     * @param maxMemory the maximum memory to use (1 or larger)
-     * @param segmentCount the number of cache segments (must be a power of 2)
-     * @param stackMoveDistance how many other item are to be moved to the top
-     *        of the stack before the current item is moved
+     * @param config the configuration
      */
     @SuppressWarnings("unchecked")
-    public CacheLongKeyLIRS(long maxMemory,
-            int segmentCount, int stackMoveDistance) {
-        setMaxMemory(maxMemory);
+    public CacheLongKeyLIRS(Config config) {
+        setMaxMemory(config.maxMemory);
+        this.nonResidentQueueSize = config.nonResidentQueueSize;
         DataUtils.checkArgument(
-                Integer.bitCount(segmentCount) == 1,
-                "The segment count must be a power of 2, is {0}", segmentCount);
-        this.segmentCount = segmentCount;
+                Integer.bitCount(config.segmentCount) == 1,
+                "The segment count must be a power of 2, is {0}", config.segmentCount);
+        this.segmentCount = config.segmentCount;
         this.segmentMask = segmentCount - 1;
-        this.stackMoveDistance = stackMoveDistance;
+        this.stackMoveDistance = config.stackMoveDistance;
         segments = new Segment[segmentCount];
         clear();
         // use the high bits for the segment
@@ -97,7 +85,7 @@ public class CacheLongKeyLIRS<V> {
         long max = Math.max(1, maxMemory / segmentCount);
         for (int i = 0; i < segmentCount; i++) {
             segments[i] = new Segment<V>(
-                    max, stackMoveDistance, 8);
+                    max, stackMoveDistance, 8, nonResidentQueueSize);
         }
     }
 
@@ -543,6 +531,12 @@ public class CacheLongKeyLIRS<V> {
          */
         private final int mask;
 
+        /**
+         * The number of entries in the non-resident queue, as a factor of the
+         * number of entries in the map.
+         */
+        private final double nonResidentQueueSize;
+
         /**
          * The stack of recently referenced elements. This includes all hot
          * entries, and the recently referenced cold entries. Resident cold
@@ -584,10 +578,13 @@ public class CacheLongKeyLIRS<V> {
          * @param stackMoveDistance the number of other entries to be moved to
          *        the top of the stack before moving an entry to the top
          * @param len the number of hash table buckets (must be a power of 2)
+         * @param nonResidentQueueSize the non-resident queue size factor
          */
-        Segment(long maxMemory, int stackMoveDistance, int len) {
+        Segment(long maxMemory, int stackMoveDistance, int len,
+                double nonResidentQueueSize) {
             setMaxMemory(maxMemory);
             this.stackMoveDistance = stackMoveDistance;
+            this.nonResidentQueueSize = nonResidentQueueSize;
 
             // the bit mask has all bits set
             mask = len - 1;
@@ -614,7 +611,7 @@ public class CacheLongKeyLIRS<V> {
          * @param len the number of hash table buckets (must be a power of 2)
          */
         Segment(Segment<V> old, int len) {
-            this(old.maxMemory, old.stackMoveDistance, len);
+            this(old.maxMemory, old.stackMoveDistance, len, old.nonResidentQueueSize);
             hits = old.hits;
             misses = old.misses;
             Entry<V> s = old.stack.stackPrev;
@@ -907,7 +904,8 @@ public class CacheLongKeyLIRS<V> {
                 e.memory = 0;
                 addToQueue(queue2, e);
                 // the size of the non-resident-cold entries needs to be limited
-                while (queue2Size + queue2Size > stackSize) {
+                int maxQueue2Size = (int) (nonResidentQueueSize * mapSize);
+                while (queue2Size > maxQueue2Size) {
                     e = queue2.queuePrev;
                     int hash = getHash(e.key);
                     remove(e.key, hash);
@@ -1151,4 +1149,32 @@ public class CacheLongKeyLIRS<V> {
 
     }
 
+    /**
+     * The cache configuration.
+     */
+    public static class Config {
+
+        /**
+         *  The maximum memory to use (1 or larger).
+         */
+        public long maxMemory = 1;
+
+        /**
+         * The number of cache segments (must be a power of 2).
+         */
+        public int segmentCount = 16;
+
+        /**
+         * How many other item are to be moved to the top of the stack before the current item is moved.
+         */
+        public int stackMoveDistance = 32;
+
+        /**
+         * The number of entries in the non-resident queue, as a factor of the
+         * number of entries in the map.
+         */
+        public double nonResidentQueueSize = 0.5;
+
+    }
+
 }

h2/src/main/org/h2/mvstore/cache/FilePathCache.java

@@ -38,9 +38,15 @@ public class FilePathCache extends FilePathWrapper {
 
         private static final int CACHE_BLOCK_SIZE = 4 * 1024;
         private final FileChannel base;
+
+        private final CacheLongKeyLIRS<ByteBuffer> cache;
+
+        {
+            CacheLongKeyLIRS.Config cc = new CacheLongKeyLIRS.Config();
             // 1 MB cache size
-        private final CacheLongKeyLIRS<ByteBuffer> cache =
-                new CacheLongKeyLIRS<ByteBuffer>(1024 * 1024);
+            cc.maxMemory = 1024 * 1024;
+            cache = new CacheLongKeyLIRS<ByteBuffer>(cc);
+        }
 
         FileCache(FileChannel base) {
             this.base = base;

h2/src/test/org/h2/test/store/TestCacheConcurrentLIRS.java

@@ -32,7 +32,9 @@ public class TestCacheConcurrentLIRS extends TestBase {
     }
 
     private void testConcurrent() {
-        final CacheLongKeyLIRS<Integer> test = new CacheLongKeyLIRS<Integer>(100);
+        CacheLongKeyLIRS.Config cc = new CacheLongKeyLIRS.Config();
+        cc.maxMemory = 100;
+        final CacheLongKeyLIRS<Integer> test = new CacheLongKeyLIRS<Integer>(cc);
         int threadCount = 8;
         final CountDownLatch wait = new CountDownLatch(1);
         final AtomicBoolean stopped = new AtomicBoolean();

h2/src/test/org/h2/test/store/TestCacheLongKeyLIRS.java

@@ -110,11 +110,11 @@ public class TestCacheLongKeyLIRS extends TestBase {
             test.put(j, j);
         }
         // for a cache of size 1000,
-        // there are 62 cold entries (about 6.25%).
-        assertEquals(62, test.size() - test.sizeHot());
+        // there are 63 cold entries (about 6.25%).
+        assertEquals(63, test.size() - test.sizeHot());
         // at most as many non-resident elements
         // as there are entries in the stack
-        assertEquals(968, test.sizeNonResident());
+        assertEquals(999, test.sizeNonResident());
     }
 
     private void verifyMapSize(int elements, int expectedMapSize) {
@@ -344,13 +344,13 @@ public class TestCacheLongKeyLIRS extends TestBase {
         verify(test, "mem: 4 stack: 4 3 2 1 cold: 4 non-resident: 0");
         assertTrue("" + test.getUsedMemory(), test.getUsedMemory() <= 4);
         test.put(6, 60, 3);
-        verify(test, "mem: 4 stack: 6 3 cold: 6 non-resident:");
+        verify(test, "mem: 4 stack: 6 3 cold: 6 non-resident: 2 1");
         assertTrue("" + test.getUsedMemory(), test.getUsedMemory() <= 4);
         test.put(7, 70, 3);
-        verify(test, "mem: 4 stack: 7 6 3 cold: 7 non-resident: 6");
+        verify(test, "mem: 4 stack: 7 6 3 cold: 7 non-resident: 6 2");
         assertTrue("" + test.getUsedMemory(), test.getUsedMemory() <= 4);
         test.put(8, 80, 4);
-        verify(test, "mem: 4 stack: 8 cold: non-resident:");
+        verify(test, "mem: 4 stack: 8 cold: non-resident: 3");
         assertTrue("" + test.getUsedMemory(), test.getUsedMemory() <= 4);
     }
 
@@ -497,7 +497,11 @@ public class TestCacheLongKeyLIRS extends TestBase {
     }
 
     private static <V> CacheLongKeyLIRS<V> createCache(int maxSize) {
-        return new CacheLongKeyLIRS<V>(maxSize, 1, 0);
+        CacheLongKeyLIRS.Config cc = new CacheLongKeyLIRS.Config();
+        cc.maxMemory = maxSize;
+        cc.segmentCount = 1;
+        cc.stackMoveDistance = 0;
+        return new CacheLongKeyLIRS<V>(cc);
     }
 
 }