HADOOP-10750. KMSKeyProviderCache should be in hadoop-common. (asuresh via tucu)

git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/branches/branch-2@1619536 13f79535-47bb-0310-9956-ffa450edef68

hadoop-common-project/hadoop-common/CHANGES.txt

@@ -151,6 +151,9 @@ Release 2.6.0 - UNRELEASED
     HADOOP-10842. CryptoExtension generateEncryptedKey method should
     receive the key name. (asuresh via tucu)
 
+    HADOOP-10750. KMSKeyProviderCache should be in hadoop-common.
+    (asuresh via tucu)
+
   BUG FIXES
 
     HADOOP-10781. Unportable getgrouplist() usage breaks FreeBSD (Dmitry

hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/crypto/key/CachingKeyProvider.java

@@ -0,0 +1,174 @@
+/**
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.apache.hadoop.crypto.key;
+
+import java.io.IOException;
+import java.security.NoSuchAlgorithmException;
+import java.util.concurrent.ExecutionException;
+import java.util.concurrent.TimeUnit;
+
+import com.google.common.cache.CacheBuilder;
+import com.google.common.cache.CacheLoader;
+import com.google.common.cache.LoadingCache;
+
+/**
+ * A <code>KeyProviderExtension</code> implementation providing a short lived
+ * cache for <code>KeyVersions</code> and <code>Metadata</code>to avoid burst
+ * of requests to hit the underlying <code>KeyProvider</code>.
+ */
+public class CachingKeyProvider extends
+    KeyProviderExtension<CachingKeyProvider.CacheExtension> {
+
+  static class CacheExtension implements KeyProviderExtension.Extension {
+    private final KeyProvider provider;
+    private LoadingCache<String, KeyVersion> keyVersionCache;
+    private LoadingCache<String, KeyVersion> currentKeyCache;
+    private LoadingCache<String, Metadata> keyMetadataCache;
+
+    CacheExtension(KeyProvider prov, long keyTimeoutMillis,
+        long currKeyTimeoutMillis) {
+      this.provider = prov;
+      keyVersionCache =
+          CacheBuilder.newBuilder().expireAfterAccess(keyTimeoutMillis,
+              TimeUnit.MILLISECONDS)
+              .build(new CacheLoader<String, KeyVersion>() {
+                @Override
+                public KeyVersion load(String key) throws Exception {
+                  KeyVersion kv = provider.getKeyVersion(key);
+                  if (kv == null) {
+                    throw new KeyNotFoundException();
+                  }
+                  return kv;
+                }
+              });
+      keyMetadataCache =
+          CacheBuilder.newBuilder().expireAfterAccess(keyTimeoutMillis,
+              TimeUnit.MILLISECONDS)
+              .build(new CacheLoader<String, Metadata>() {
+                @Override
+                public Metadata load(String key) throws Exception {
+                  Metadata meta = provider.getMetadata(key);
+                  if (meta == null) {
+                    throw new KeyNotFoundException();
+                  }
+                  return meta;
+                }
+              });
+      currentKeyCache =
+          CacheBuilder.newBuilder().expireAfterWrite(currKeyTimeoutMillis,
+          TimeUnit.MILLISECONDS)
+          .build(new CacheLoader<String, KeyVersion>() {
+            @Override
+            public KeyVersion load(String key) throws Exception {
+              KeyVersion kv = provider.getCurrentKey(key);
+              if (kv == null) {
+                throw new KeyNotFoundException();
+              }
+              return kv;
+            }
+          });
+    }
+  }
+
+  @SuppressWarnings("serial")
+  private static class KeyNotFoundException extends Exception { }
+
+  public CachingKeyProvider(KeyProvider keyProvider, long keyTimeoutMillis,
+      long currKeyTimeoutMillis) {
+    super(keyProvider, new CacheExtension(keyProvider, keyTimeoutMillis,
+        currKeyTimeoutMillis));
+  }
+
+  @Override
+  public KeyVersion getCurrentKey(String name) throws IOException {
+    try {
+      return getExtension().currentKeyCache.get(name);
+    } catch (ExecutionException ex) {
+      Throwable cause = ex.getCause();
+      if (cause instanceof KeyNotFoundException) {
+        return null;
+      } else if (cause instanceof IOException) {
+        throw (IOException) cause;
+      } else {
+        throw new IOException(cause);
+      }
+    }
+  }
+
+  @Override
+  public KeyVersion getKeyVersion(String versionName)
+      throws IOException {
+    try {
+      return getExtension().keyVersionCache.get(versionName);
+    } catch (ExecutionException ex) {
+      Throwable cause = ex.getCause();
+      if (cause instanceof KeyNotFoundException) {
+        return null;
+      } else if (cause instanceof IOException) {
+        throw (IOException) cause;
+      } else {
+        throw new IOException(cause);
+      }
+    }
+  }
+
+  @Override
+  public void deleteKey(String name) throws IOException {
+    getKeyProvider().deleteKey(name);
+    getExtension().currentKeyCache.invalidate(name);
+    getExtension().keyMetadataCache.invalidate(name);
+    // invalidating all key versions as we don't know
+    // which ones belonged to the deleted key
+    getExtension().keyVersionCache.invalidateAll();
+  }
+
+  @Override
+  public KeyVersion rollNewVersion(String name, byte[] material)
+      throws IOException {
+    KeyVersion key = getKeyProvider().rollNewVersion(name, material);
+    getExtension().currentKeyCache.invalidate(name);
+    getExtension().keyMetadataCache.invalidate(name);
+    return key;
+  }
+
+  @Override
+  public KeyVersion rollNewVersion(String name)
+      throws NoSuchAlgorithmException, IOException {
+    KeyVersion key = getKeyProvider().rollNewVersion(name);
+    getExtension().currentKeyCache.invalidate(name);
+    getExtension().keyMetadataCache.invalidate(name);
+    return key;
+  }
+
+  @Override
+  public Metadata getMetadata(String name) throws IOException {
+    try {
+      return getExtension().keyMetadataCache.get(name);
+    } catch (ExecutionException ex) {
+      Throwable cause = ex.getCause();
+      if (cause instanceof KeyNotFoundException) {
+        return null;
+      } else if (cause instanceof IOException) {
+        throw (IOException) cause;
+      } else {
+        throw new IOException(cause);
+      }
+    }
+  }
+
+}

hadoop-common-project/hadoop-common/src/test/java/org/apache/hadoop/crypto/key/TestCachingKeyProvider.java

@@ -15,17 +15,16 @@
  * See the License for the specific language governing permissions and
  * limitations under the License.
  */
-package org.apache.hadoop.crypto.key.kms.server;
+package org.apache.hadoop.crypto.key;
+
+import java.util.Date;
 
-import org.apache.hadoop.crypto.key.KeyProvider;
 import org.apache.hadoop.crypto.key.kms.KMSClientProvider;
 import org.junit.Assert;
 import org.junit.Test;
 import org.mockito.Mockito;
 
-import java.util.Date;
-
-public class TestKMSCacheKeyProvider {
+public class TestCachingKeyProvider {
 
   @Test
   public void testCurrentKey() throws Exception {
@@ -33,7 +32,7 @@ public class TestKMSCacheKeyProvider {
     KeyProvider mockProv = Mockito.mock(KeyProvider.class);
     Mockito.when(mockProv.getCurrentKey(Mockito.eq("k1"))).thenReturn(mockKey);
     Mockito.when(mockProv.getCurrentKey(Mockito.eq("k2"))).thenReturn(null);
-    KeyProvider cache = new KMSCacheKeyProvider(mockProv, 100);
+    KeyProvider cache = new CachingKeyProvider(mockProv, 100, 100);
 
     // asserting caching
     Assert.assertEquals(mockKey, cache.getCurrentKey("k1"));
@@ -45,7 +44,7 @@ public class TestKMSCacheKeyProvider {
     Mockito.verify(mockProv, Mockito.times(2)).getCurrentKey(Mockito.eq("k1"));
 
     // asserting no caching when key is not known
-    cache = new KMSCacheKeyProvider(mockProv, 100);
+    cache = new CachingKeyProvider(mockProv, 100, 100);
     Assert.assertEquals(null, cache.getCurrentKey("k2"));
     Mockito.verify(mockProv, Mockito.times(1)).getCurrentKey(Mockito.eq("k2"));
     Assert.assertEquals(null, cache.getCurrentKey("k2"));
@@ -56,25 +55,56 @@ public class TestKMSCacheKeyProvider {
   public void testKeyVersion() throws Exception {
     KeyProvider.KeyVersion mockKey = Mockito.mock(KeyProvider.KeyVersion.class);
     KeyProvider mockProv = Mockito.mock(KeyProvider.class);
-    Mockito.when(mockProv.getKeyVersion(Mockito.eq("k1@0"))).thenReturn(mockKey);
+    Mockito.when(mockProv.getKeyVersion(Mockito.eq("k1@0")))
+        .thenReturn(mockKey);
     Mockito.when(mockProv.getKeyVersion(Mockito.eq("k2@0"))).thenReturn(null);
-    KeyProvider cache = new KMSCacheKeyProvider(mockProv, 100);
+    KeyProvider cache = new CachingKeyProvider(mockProv, 100, 100);
 
     // asserting caching
     Assert.assertEquals(mockKey, cache.getKeyVersion("k1@0"));
-    Mockito.verify(mockProv, Mockito.times(1)).getKeyVersion(Mockito.eq("k1@0"));
+    Mockito.verify(mockProv, Mockito.times(1))
+        .getKeyVersion(Mockito.eq("k1@0"));
     Assert.assertEquals(mockKey, cache.getKeyVersion("k1@0"));
-    Mockito.verify(mockProv, Mockito.times(1)).getKeyVersion(Mockito.eq("k1@0"));
+    Mockito.verify(mockProv, Mockito.times(1))
+        .getKeyVersion(Mockito.eq("k1@0"));
     Thread.sleep(200);
     Assert.assertEquals(mockKey, cache.getKeyVersion("k1@0"));
-    Mockito.verify(mockProv, Mockito.times(2)).getKeyVersion(Mockito.eq("k1@0"));
+    Mockito.verify(mockProv, Mockito.times(2))
+        .getKeyVersion(Mockito.eq("k1@0"));
 
     // asserting no caching when key is not known
-    cache = new KMSCacheKeyProvider(mockProv, 100);
+    cache = new CachingKeyProvider(mockProv, 100, 100);
     Assert.assertEquals(null, cache.getKeyVersion("k2@0"));
-    Mockito.verify(mockProv, Mockito.times(1)).getKeyVersion(Mockito.eq("k2@0"));
+    Mockito.verify(mockProv, Mockito.times(1))
+        .getKeyVersion(Mockito.eq("k2@0"));
     Assert.assertEquals(null, cache.getKeyVersion("k2@0"));
-    Mockito.verify(mockProv, Mockito.times(2)).getKeyVersion(Mockito.eq("k2@0"));
+    Mockito.verify(mockProv, Mockito.times(2))
+        .getKeyVersion(Mockito.eq("k2@0"));
+  }
+
+  @Test
+  public void testMetadata() throws Exception {
+    KeyProvider.Metadata mockMeta = Mockito.mock(KeyProvider.Metadata.class);
+    KeyProvider mockProv = Mockito.mock(KeyProvider.class);
+    Mockito.when(mockProv.getMetadata(Mockito.eq("k1"))).thenReturn(mockMeta);
+    Mockito.when(mockProv.getMetadata(Mockito.eq("k2"))).thenReturn(null);
+    KeyProvider cache = new CachingKeyProvider(mockProv, 100, 100);
+
+    // asserting caching
+    Assert.assertEquals(mockMeta, cache.getMetadata("k1"));
+    Mockito.verify(mockProv, Mockito.times(1)).getMetadata(Mockito.eq("k1"));
+    Assert.assertEquals(mockMeta, cache.getMetadata("k1"));
+    Mockito.verify(mockProv, Mockito.times(1)).getMetadata(Mockito.eq("k1"));
+    Thread.sleep(200);
+    Assert.assertEquals(mockMeta, cache.getMetadata("k1"));
+    Mockito.verify(mockProv, Mockito.times(2)).getMetadata(Mockito.eq("k1"));
+
+    // asserting no caching when key is not known
+    cache = new CachingKeyProvider(mockProv, 100, 100);
+    Assert.assertEquals(null, cache.getMetadata("k2"));
+    Mockito.verify(mockProv, Mockito.times(1)).getMetadata(Mockito.eq("k2"));
+    Assert.assertEquals(null, cache.getMetadata("k2"));
+    Mockito.verify(mockProv, Mockito.times(2)).getMetadata(Mockito.eq("k2"));
   }
 
   @Test
@@ -82,7 +112,7 @@ public class TestKMSCacheKeyProvider {
     KeyProvider.KeyVersion mockKey = Mockito.mock(KeyProvider.KeyVersion.class);
     KeyProvider mockProv = Mockito.mock(KeyProvider.class);
     Mockito.when(mockProv.getCurrentKey(Mockito.eq("k1"))).thenReturn(mockKey);
-    KeyProvider cache = new KMSCacheKeyProvider(mockProv, 100);
+    KeyProvider cache = new CachingKeyProvider(mockProv, 100, 100);
     Assert.assertEquals(mockKey, cache.getCurrentKey("k1"));
     Mockito.verify(mockProv, Mockito.times(1)).getCurrentKey(Mockito.eq("k1"));
     cache.rollNewVersion("k1");
@@ -100,21 +130,23 @@ public class TestKMSCacheKeyProvider {
     KeyProvider.KeyVersion mockKey = Mockito.mock(KeyProvider.KeyVersion.class);
     KeyProvider mockProv = Mockito.mock(KeyProvider.class);
     Mockito.when(mockProv.getCurrentKey(Mockito.eq("k1"))).thenReturn(mockKey);
-    Mockito.when(mockProv.getKeyVersion(Mockito.eq("k1@0"))).thenReturn(mockKey);
+    Mockito.when(mockProv.getKeyVersion(Mockito.eq("k1@0")))
+        .thenReturn(mockKey);
     Mockito.when(mockProv.getMetadata(Mockito.eq("k1"))).thenReturn(
         new KMSClientProvider.KMSMetadata("c", 0, "l", null, new Date(), 1));
-    KeyProvider cache = new KMSCacheKeyProvider(mockProv, 100);
+    KeyProvider cache = new CachingKeyProvider(mockProv, 100, 100);
     Assert.assertEquals(mockKey, cache.getCurrentKey("k1"));
     Mockito.verify(mockProv, Mockito.times(1)).getCurrentKey(Mockito.eq("k1"));
     Assert.assertEquals(mockKey, cache.getKeyVersion("k1@0"));
-    Mockito.verify(mockProv, Mockito.times(1)).getKeyVersion(Mockito.eq("k1@0"));
+    Mockito.verify(mockProv, Mockito.times(1))
+        .getKeyVersion(Mockito.eq("k1@0"));
     cache.deleteKey("k1");
 
     // asserting the cache is purged
     Assert.assertEquals(mockKey, cache.getCurrentKey("k1"));
     Mockito.verify(mockProv, Mockito.times(2)).getCurrentKey(Mockito.eq("k1"));
     Assert.assertEquals(mockKey, cache.getKeyVersion("k1@0"));
-    Mockito.verify(mockProv, Mockito.times(2)).getKeyVersion(Mockito.eq("k1@0"));
+    Mockito.verify(mockProv, Mockito.times(2))
+        .getKeyVersion(Mockito.eq("k1@0"));
   }
-
 }

hadoop-common-project/hadoop-kms/src/main/java/org/apache/hadoop/crypto/key/kms/server/KMSCacheKeyProvider.java

@@ -1,177 +0,0 @@
-/**
- * Licensed to the Apache Software Foundation (ASF) under one
- * or more contributor license agreements.  See the NOTICE file
- * distributed with this work for additional information
- * regarding copyright ownership.  The ASF licenses this file
- * to you under the Apache License, Version 2.0 (the
- * "License"); you may not use this file except in compliance
- * with the License.  You may obtain a copy of the License at
- *
- *     http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
- */
-package org.apache.hadoop.crypto.key.kms.server;
-
-import com.google.common.cache.CacheBuilder;
-import com.google.common.cache.CacheLoader;
-import com.google.common.cache.LoadingCache;
-import org.apache.hadoop.crypto.key.KeyProvider;
-
-import java.io.IOException;
-import java.security.NoSuchAlgorithmException;
-import java.util.ArrayList;
-import java.util.List;
-import java.util.Map;
-import java.util.concurrent.ExecutionException;
-import java.util.concurrent.TimeUnit;
-
-/**
- * A <code>KeyProvider</code> proxy implementation providing a short lived
- * cache for <code>KeyVersions</code> to avoid burst of requests to hit the
- * underlying <code>KeyProvider</code>.
- */
-public class KMSCacheKeyProvider extends KeyProvider {
-  private final KeyProvider provider;
-  private LoadingCache<String, KeyVersion> keyVersionCache;
-  private LoadingCache<String, KeyVersion> currentKeyCache;
-
-  private static class KeyNotFoundException extends Exception {
-    private static final long serialVersionUID = 1L;
-  }
-
-  public KMSCacheKeyProvider(KeyProvider prov, long timeoutMillis) {
-    this.provider =  prov;
-    keyVersionCache = CacheBuilder.newBuilder().expireAfterAccess(timeoutMillis,
-        TimeUnit.MILLISECONDS).build(new CacheLoader<String, KeyVersion>() {
-      @Override
-      public KeyVersion load(String key) throws Exception {
-        KeyVersion kv = provider.getKeyVersion(key);
-        if (kv == null) {
-          throw new KeyNotFoundException();
-        }
-        return kv;
-      }
-    });
-    // for current key we don't want to go stale for more than 1 sec
-    currentKeyCache = CacheBuilder.newBuilder().expireAfterWrite(1000,
-        TimeUnit.MILLISECONDS).build(new CacheLoader<String, KeyVersion>() {
-      @Override
-      public KeyVersion load(String key) throws Exception {
-        KeyVersion kv =  provider.getCurrentKey(key);
-        if (kv == null) {
-          throw new KeyNotFoundException();
-        }
-        return kv;
-      }
-    });
-  }
-
-  @Override
-  public KeyVersion getCurrentKey(String name) throws IOException {
-    try {
-      return currentKeyCache.get(name);
-    } catch (ExecutionException ex) {
-      Throwable cause = ex.getCause();
-      if (cause instanceof KeyNotFoundException) {
-        return null;
-      } else if (cause instanceof IOException) {
-        throw (IOException) cause;
-      } else {
-        throw new IOException(cause);
-      }
-    }
-  }
-
-  @Override
-  public KeyVersion getKeyVersion(String versionName)
-      throws IOException {
-    try {
-      return keyVersionCache.get(versionName);
-    } catch (ExecutionException ex) {
-      Throwable cause = ex.getCause();
-      if (cause instanceof KeyNotFoundException) {
-        return null;
-      } else if (cause instanceof IOException) {
-        throw (IOException) cause;
-      } else {
-        throw new IOException(cause);
-      }
-    }
-  }
-
-  @Override
-  public List<String> getKeys() throws IOException {
-    return provider.getKeys();
-  }
-
-  @Override
-  public List<KeyVersion> getKeyVersions(String name)
-      throws IOException {
-    return provider.getKeyVersions(name);
-  }
-
-  @Override
-  public Metadata getMetadata(String name) throws IOException {
-    return provider.getMetadata(name);
-  }
-
-  @Override
-  public KeyVersion createKey(String name, byte[] material,
-      Options options) throws IOException {
-    return provider.createKey(name, material, options);
-  }
-
-  @Override
-  public KeyVersion createKey(String name,
-      Options options)
-      throws NoSuchAlgorithmException, IOException {
-    return provider.createKey(name, options);
-  }
-
-  @Override
-  public void deleteKey(String name) throws IOException {
-    provider.deleteKey(name);
-    currentKeyCache.invalidate(name);
-    // invalidating all key versions as we don't know which ones belonged to the
-    // deleted key
-    keyVersionCache.invalidateAll();
-  }
-
-  @Override
-  public KeyVersion rollNewVersion(String name, byte[] material)
-      throws IOException {
-    KeyVersion key = provider.rollNewVersion(name, material);
-    currentKeyCache.invalidate(name);
-    return key;
-  }
-
-  @Override
-  public KeyVersion rollNewVersion(String name)
-      throws NoSuchAlgorithmException, IOException {
-    KeyVersion key = provider.rollNewVersion(name);
-    currentKeyCache.invalidate(name);
-    return key;
-  }
-
-  @Override
-  public void flush() throws IOException {
-    provider.flush();
-  }
-
-  @Override
-  public Metadata[] getKeysMetadata(String ... keyNames)
-      throws IOException {
-    return provider.getKeysMetadata(keyNames);
-  }
-
-  @Override
-  public boolean isTransient() {
-    return provider.isTransient();
-  }
-
-}

hadoop-common-project/hadoop-kms/src/main/java/org/apache/hadoop/crypto/key/kms/server/KMSConfiguration.java

@@ -34,9 +34,21 @@ public class KMSConfiguration {
 
   public static final String CONFIG_PREFIX = "hadoop.kms.";
 
+  // Property to Enable/Disable Caching
+  public static final String KEY_CACHE_ENABLE = CONFIG_PREFIX +
+      "cache.enable";
+  // Timeout for the Key and Metadata Cache
   public static final String KEY_CACHE_TIMEOUT_KEY = CONFIG_PREFIX +
       "cache.timeout.ms";
-  public static final long KEY_CACHE_TIMEOUT_DEFAULT = 10 * 1000; // 10 secs
+  // TImeout for the Current Key cache
+  public static final String CURR_KEY_CACHE_TIMEOUT_KEY = CONFIG_PREFIX +
+      "current.key.cache.timeout.ms";
+
+  public static final boolean KEY_CACHE_ENABLE_DEFAULT = true;
+  // 10 mins
+  public static final long KEY_CACHE_TIMEOUT_DEFAULT = 10 * 60 * 1000;
+  // 30 secs
+  public static final long CURR_KEY_CACHE_TIMEOUT_DEFAULT = 30 * 1000;
 
   static Configuration getConfiguration(boolean loadHadoopDefaults,
       String ... resources) {

hadoop-common-project/hadoop-kms/src/main/java/org/apache/hadoop/crypto/key/kms/server/KMSWebApp.java

@@ -22,6 +22,7 @@ import com.codahale.metrics.Meter;
 import com.codahale.metrics.MetricRegistry;
 import org.apache.hadoop.classification.InterfaceAudience;
 import org.apache.hadoop.conf.Configuration;
+import org.apache.hadoop.crypto.key.CachingKeyProvider;
 import org.apache.hadoop.crypto.key.KeyProvider;
 import org.apache.hadoop.crypto.key.KeyProviderFactory;
 import org.apache.hadoop.http.HttpServer2;
@@ -150,10 +151,17 @@ public class KMSWebApp implements ServletContextListener {
             kmsConf.get(KeyProviderFactory.KEY_PROVIDER_PATH));
       }
       keyProvider = providers.get(0);
-      long timeOutMillis =
+      if (kmsConf.getBoolean(KMSConfiguration.KEY_CACHE_ENABLE,
+          KMSConfiguration.KEY_CACHE_ENABLE_DEFAULT)) {
+        long keyTimeOutMillis =
             kmsConf.getLong(KMSConfiguration.KEY_CACHE_TIMEOUT_KEY,
                 KMSConfiguration.KEY_CACHE_TIMEOUT_DEFAULT);
-      keyProvider = new KMSCacheKeyProvider(keyProvider, timeOutMillis);
+        long currKeyTimeOutMillis =
+            kmsConf.getLong(KMSConfiguration.CURR_KEY_CACHE_TIMEOUT_KEY,
+                KMSConfiguration.CURR_KEY_CACHE_TIMEOUT_DEFAULT);
+        keyProvider = new CachingKeyProvider(keyProvider, keyTimeOutMillis,
+            currKeyTimeOutMillis);
+      }
 
       LOG.info("KMS Started");
     } catch (Throwable ex) {

hadoop-common-project/hadoop-kms/src/site/apt/index.apt.vm

@@ -72,22 +72,35 @@ Hadoop Key Management Server (KMS) - Documentation Sets ${project.version}
   KMS caches keys for short period of time to avoid excessive hits to the
   underlying key provider.
 
-  The cache is used with the following 2 methods only, <<<getCurrentKey()>>>
-  and <<<getKeyVersion()>>>.
+  The Cache is enabled by default (can be dissabled by setting the
+  <<<hadoop.kms.cache.enable>>> boolean property to false)
+
+  The cache is used with the following 3 methods only, <<<getCurrentKey()>>>
+  and <<<getKeyVersion()>>> and <<<getMetadata()>>>.
 
   For the <<<getCurrentKey()>>> method, cached entries are kept for a maximum
-  of 1000 millisecond regardless the number of times the key is being access
+  of 30000 millisecond regardless the number of times the key is being access
   (to avoid stale keys to be considered current).
 
   For the <<<getKeyVersion()>>> method, cached entries are kept with a default
-  inactivity timeout of 10000 milliseconds. This time out is configurable via
-  the following property in the <<<etc/hadoop/kms-site.xml>>> configuration
-  file:
+  inactivity timeout of 600000 milliseconds (10 mins). This time out is
+  configurable via the following property in the <<<etc/hadoop/kms-site.xml>>>
+  configuration file:
 
 +---+
+  <property>
+    <name>hadoop.kms.cache.enable</name>
+    <value>true</value>
+  </property>
+
   <property>
     <name>hadoop.kms.cache.timeout.ms</name>
-    <value>10000</value>
+    <value>600000</value>
+  </property>
+
+  <property>
+    <name>hadoop.kms.current.key.cache.timeout.ms</name>
+    <value>30000</value>
   </property>
 +---+