[helix] 02/19: Created Helix distributed lock interface (#703)

[jx...@apache.org]

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jxue pushed a commit to branch distributed-lock
in repository https://gitbox.apache.org/repos/asf/helix.git

commit 5bea978211dad46fd20aaf6f16f751e72b8b5c89
Author: mgao0 <31...@users.noreply.github.com>
AuthorDate: Thu Jan 30 13:39:16 2020 -0800

    Created Helix distributed lock interface (#703)
    
    Added LockInfo interfaces.
---
 .../main/java/org/apache/helix/lock/HelixLock.java | 53 ++++++++++++++++++++++
 .../main/java/org/apache/helix/lock/LockInfo.java  | 46 +++++++++++++++++++
 2 files changed, 99 insertions(+)

diff --git a/helix-lock/src/main/java/org/apache/helix/lock/HelixLock.java b/helix-lock/src/main/java/org/apache/helix/lock/HelixLock.java
new file mode 100644
index 0000000..01ef63b
--- /dev/null
+++ b/helix-lock/src/main/java/org/apache/helix/lock/HelixLock.java
@@ -0,0 +1,53 @@
+package org.apache.helix.lock;
+
+/*
+ * 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.
+ */
+
+/**
+ * Generic interface for Helix distributed lock
+ */
+public interface HelixLock<T> {
+  /**
+   * Blocking call to acquire a lock
+   * @return true if the lock was successfully acquired,
+   * false if the lock could not be acquired
+   */
+  boolean acquireLock();
+
+  /**
+   * Blocking call to release a lock
+   * @return true if the lock was successfully released,
+   * false if the locked is not locked or is not locked by the user,
+   * or the lock could not be released
+   */
+  boolean releaseLock();
+
+  /**
+   * Retrieve the lock information, e.g. lock timeout, lock message, etc.
+   * @return lock metadata information
+   */
+  LockInfo<T> getLockInfo();
+
+  /**
+   * If the user is current lock owner
+   * @return true if the user is the lock owner,
+   * false if the user is not the lock owner or the lock doesn't have a owner
+   */
+  boolean isOwner();
+}
diff --git a/helix-lock/src/main/java/org/apache/helix/lock/LockInfo.java b/helix-lock/src/main/java/org/apache/helix/lock/LockInfo.java
new file mode 100644
index 0000000..30322bb
--- /dev/null
+++ b/helix-lock/src/main/java/org/apache/helix/lock/LockInfo.java
@@ -0,0 +1,46 @@
+/*
+ * 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.helix.lock;
+
+import java.util.Map;
+
+
+/**
+ * Generic interface for a map contains the Helix lock information
+ * @param <T> The type of the LockInfo value
+ */
+public interface LockInfo<T> {
+
+  //TODO: add specific setter and getter for any field that is determined to be universal for all implementations of HelixLock
+
+  /**
+   * Create a single filed of LockInfo, or update the value of the field if it already exists
+   * @param infoKey the key of the LockInfo field
+   * @param infoValue the value of the LockInfo field
+   */
+  void setInfoValue(String infoKey, T infoValue);
+
+  /**
+   * Get the value of a field in LockInfo
+   * @param infoKey the key of the LockInfo field
+   * @return the value of the field or null if this key does not exist
+   */
+  T getInfoValue(String infoKey);
+}