Fix for issue #413: Circuit Breaker Pattern (#986)

* Fix Issue #413: Circuit-Breaker Pattern

* Fix Image Links

* Remove Javadoc plugin to ensure correct build

* Implementing code review feedback

* Sync README with actual code

circuit-breaker/src/test/java/com/iluwatar/circuitbreaker/CircuitBreakerTest.java

@@ -0,0 +1,80 @@
+/**
+ * The MIT License
+ * Copyright (c) 2014 Ilkka Seppälä
+ *
+ * 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:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * 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.circuitbreaker;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+import org.junit.jupiter.api.Test;
+
+/**
+ * 
+ * Circuit Breaker test
+ *
+ */
+public class CircuitBreakerTest {
+
+  //long timeout, int failureThreshold, long retryTimePeriod
+  @Test
+  public void testSetState() {
+    var circuitBreaker = new CircuitBreaker(1,1,100);
+    //Right now, failureCount<failureThreshold, so state should be closed
+    assertEquals(circuitBreaker.getState(), "CLOSED");
+    circuitBreaker.failureCount = 4;
+    circuitBreaker.lastFailureTime = System.nanoTime();
+    circuitBreaker.setState();
+    //Since failureCount>failureThreshold, and lastFailureTime is nearly equal to current time,
+    //state should be half-open
+    assertEquals(circuitBreaker.getState(), "HALF_OPEN");
+    //Since failureCount>failureThreshold, and lastFailureTime is much lesser current time,
+    //state should be open
+    circuitBreaker.lastFailureTime = System.nanoTime() - 1000 * 1000 * 1000 * 1000;
+    circuitBreaker.setState();
+    assertEquals(circuitBreaker.getState(), "OPEN");
+    //Now set it back again to closed to test idempotency
+    circuitBreaker.failureCount = 0;
+    circuitBreaker.setState();
+    assertEquals(circuitBreaker.getState(), "CLOSED");
+  }
+  
+  @Test
+  public void testSetStateForBypass() {
+    var circuitBreaker = new CircuitBreaker(1,1,100);
+    //Right now, failureCount<failureThreshold, so state should be closed
+    //Bypass it and set it to open
+    circuitBreaker.setStateForBypass(State.OPEN);
+    assertEquals(circuitBreaker.getState(), "OPEN");
+  }
+  
+  @Test
+  public void testApiResponses() {
+    var circuitBreaker = new CircuitBreaker(1,1,100);
+    try {
+      //Call with the paramater start_time set to huge amount of time in past so that service 
+      //replies with "Ok". Also, state is CLOSED in start
+      var response = circuitBreaker.call("delayedService", System.nanoTime() - 60 * 1000 * 1000 * 1000);
+      assertEquals(response, "Delayed service is working");
+    } catch (Exception e) {
+      System.out.println(e.getMessage());
+    }
+  }
+}

circuit-breaker/src/test/java/com/iluwatar/circuitbreaker/DelayedServiceTest.java

@@ -0,0 +1,42 @@
+/**
+ * The MIT License
+ * Copyright (c) 2014 Ilkka Seppälä
+ *
+ * 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:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * 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.circuitbreaker;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+import org.junit.jupiter.api.Test;
+
+/**
+ * 
+ * Monitoring Service test
+ *
+ */
+public class DelayedServiceTest {
+
+  //Improves code coverage
+  @Test
+  public void testDefaultConstructor() {
+    var obj = new DelayedService();
+    assertEquals(obj.response(System.nanoTime()), "Delayed service is down");
+  }
+}

circuit-breaker/src/test/java/com/iluwatar/circuitbreaker/MonitoringServiceTest.java

@@ -0,0 +1,63 @@
+/**
+ * The MIT License
+ * Copyright (c) 2014 Ilkka Seppälä
+ *
+ * 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:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * 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.circuitbreaker;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+import org.junit.jupiter.api.Test;
+
+/**
+ * 
+ * Monitoring Service test
+ *
+ */
+public class MonitoringServiceTest {
+
+  //long timeout, int failureThreshold, long retryTimePeriod
+  @Test
+  public void testLocalResponse() {
+    var monitoringService = new MonitoringService();
+    var response = monitoringService.localResourceResponse();
+    assertEquals(response, "Local Service is working");
+  }
+  
+  @Test
+  public void testRemoteResponse() {
+    var monitoringService = new MonitoringService();
+    var circuitBreaker = new CircuitBreaker(1,1,100);
+    //Set time in past to make the server work
+    var serverStartTime = System.nanoTime() / 10;
+    var response = monitoringService.remoteResourceResponse(circuitBreaker, serverStartTime);
+    assertEquals(response, "Delayed service is working");
+  }
+  
+  @Test
+  public void testRemoteResponse2() {
+    MonitoringService monitoringService = new MonitoringService();
+    CircuitBreaker circuitBreaker = new CircuitBreaker(1,1,100);
+    //Set time as current time as initially server fails
+    long serverStartTime = System.nanoTime();
+    String response = monitoringService.remoteResourceResponse(circuitBreaker, serverStartTime);
+    assertEquals(response, "Remote service not responding");
+  }
+}