Add SecondaryCache Java API

Author: mike-evolved

java/src/main/java/org/rocksdb/SecondaryCache.java

@@ -0,0 +1,76 @@
+// Copyright (c) 2011-present, Facebook, Inc.  All rights reserved.
+//  This source code is licensed under both the GPLv2 (found in the
+//  COPYING file in the root directory) and Apache 2.0 License
+//  (found in the LICENSE.Apache file in the root directory).
+
+package org.rocksdb;
+
+/**
+ * Second-tier cache below the primary block cache.
+ * Stores blocks in compressed form or on non-volatile storage.
+ */
+public abstract class SecondaryCache extends RocksObject {
+
+  protected SecondaryCache(final long nativeHandle) {
+    super(nativeHandle);
+  }
+
+  @Override
+  protected final void disposeInternal(final long handle) {
+    disposeInternalJni(handle);
+  }
+
+  /**
+   * Creates a CompressedSecondaryCache with default settings.
+   *
+   * @param capacity cache size in bytes
+   * @return a new CompressedSecondaryCache
+   */
+  public static SecondaryCache newCompressedSecondaryCache(final long capacity) {
+    return new CompressedSecondaryCache(capacity);
+  }
+
+  /**
+   * Creates a CompressedSecondaryCache with custom options.
+   *
+   * @param capacity cache size in bytes
+   * @param numShardBits shard bits (2^n shards), -1 for auto
+   * @param strictCapacityLimit if true, reject inserts when full
+   * @param highPriPoolRatio fraction reserved for high-priority entries (0.0-1.0)
+   * @return a new CompressedSecondaryCache
+   */
+  public static SecondaryCache newCompressedSecondaryCache(
+      final long capacity,
+      final int numShardBits,
+      final boolean strictCapacityLimit,
+      final double highPriPoolRatio) {
+    return new CompressedSecondaryCache(
+        capacity, numShardBits, strictCapacityLimit, highPriPoolRatio);
+  }
+
+  /**
+   * Compressed cache using LZ4 compression.
+   */
+  private static class CompressedSecondaryCache extends SecondaryCache {
+
+    private CompressedSecondaryCache(final long capacity) {
+      super(newCompressedSecondaryCacheInstance(capacity));
+    }
+
+    private CompressedSecondaryCache(
+        final long capacity,
+        final int numShardBits,
+        final boolean strictCapacityLimit,
+        final double highPriPoolRatio) {
+      super(newCompressedSecondaryCacheInstance(
+          capacity, numShardBits, strictCapacityLimit, highPriPoolRatio));
+    }
+
+    private static native long newCompressedSecondaryCacheInstance(long capacity);
+
+    private static native long newCompressedSecondaryCacheInstance(
+        long capacity, int numShardBits, boolean strictCapacityLimit, double highPriPoolRatio);
+  }
+
+  private static native void disposeInternalJni(final long handle);
+}