Leader Election Pattern (#923)

* Fix issue #761: ThreadSafeDoubleCheckLocking.java: Instantiating by Reflection call will be successful if you do that firstly * Create leader election module * Create Interface of Instance and MessageManager * Create implementations with token ring algorithm * Change package structure. Create basic message system. * Implement heartbeat and heartbeat invoking message system * Implement election message handler * Add leader message handler * Add main entry point * Add comments * Update README.md * Fix checkstyle issue * Add Unit Tests * Add Unit Tests * Add bully leader selection * Change System.out to log print. Add MIT license in each file. * Add More java doc comments * Add unit test * Add unit tests
2019-10-08 23:29:59 +08:00
parent 41b8d80479
commit 90ea4506ca
22 changed files with 1719 additions and 0 deletions
--- a/leader-election/src/main/java/com/iluwatar/leaderelection/AbstractMessageManager.java
+++ b/leader-election/src/main/java/com/iluwatar/leaderelection/AbstractMessageManager.java
@@ -0,0 +1,73 @@
+/**
+ * The MIT License
+ * Copyright (c) 2014-2016 Ilkka Seppälä
+ * <p>
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ * <p>
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ * <p>
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+ * THE SOFTWARE.
+ */
+
+package com.iluwatar.leaderelection;
+
+import java.util.List;
+import java.util.Map;
+import java.util.stream.Collectors;
+
+/**
+ * Abstract class of all the message manager classes.
+ */
+public abstract class AbstractMessageManager implements MessageManager {
+
+  /**
+   * Contain all the instances in the system. Key is its ID, and value is the instance itself.
+   */
+  protected Map<Integer, Instance> instanceMap;
+
+  /**
+   * Construtor of AbstractMessageManager
+   */
+  public AbstractMessageManager(Map<Integer, Instance> instanceMap) {
+    this.instanceMap = instanceMap;
+  }
+
+  /**
+   * Find the next instance with smallest ID.
+   * @return The next instance.
+   */
+  protected Instance findNextInstance(int currentId) {
+    Instance result = null;
+    List<Integer> candidateList = instanceMap.keySet()
+          .stream()
+          .filter((i) -> i > currentId && instanceMap.get(i).isAlive())
+          .sorted()
+          .collect(Collectors.toList());
+    if (candidateList.isEmpty()) {
+      int index = instanceMap.keySet()
+          .stream()
+          .filter((i) -> instanceMap.get(i).isAlive())
+          .sorted()
+          .collect(Collectors.toList())
+          .get(0);
+      result = instanceMap.get(index);
+    } else {
+      int index = candidateList.get(0);
+      result = instanceMap.get(index);
+    }
+    return result;
+  }
+
+}