Introducing builder pattern on AsyncEventHandler (#293)

Author: aliabbasrizvi

core-httpclient-impl/src/main/java/com/optimizely/ab/event/AsyncEventHandler.java

@@ -47,19 +47,24 @@
  * {@link EventHandler} implementation that queues events and has a separate pool of threads responsible
  * for the dispatch.
  */
-public class AsyncEventHandler implements EventHandler {
+public class AsyncEventHandler implements EventHandler, AutoCloseable {
 
     private static final Logger logger = LoggerFactory.getLogger(AsyncEventHandler.class);
     private static final ProjectConfigResponseHandler EVENT_RESPONSE_HANDLER = new ProjectConfigResponseHandler();
 
     private final OptimizelyHttpClient httpClient;
     private final ExecutorService workerExecutor;
 
-    public AsyncEventHandler(int queueCapacity, int numWorkers) {
-        this(queueCapacity, numWorkers, 200, 20, 5000);
-    }
+    private final long closeTimeout;
+    private final TimeUnit closeTimeoutUnit;
 
-    public AsyncEventHandler(int queueCapacity, int numWorkers, int maxConnections, int connectionsPerRoute, int validateAfter) {
+    public AsyncEventHandler(int queueCapacity,
+                             int numWorkers,
+                             int maxConnections,
+                             int connectionsPerRoute,
+                             int validateAfter,
+                             long closeTimeout,
+                             TimeUnit closeTimeoutUnit) {
         if (queueCapacity <= 0) {
             throw new IllegalArgumentException("queue capacity must be > 0");
         }
@@ -74,12 +79,17 @@ public AsyncEventHandler(int queueCapacity, int numWorkers, int maxConnections,
             0L, TimeUnit.MILLISECONDS,
             new ArrayBlockingQueue<Runnable>(queueCapacity),
             new NamedThreadFactory("optimizely-event-dispatcher-thread-%s", true));
+
+        this.closeTimeout = closeTimeout;
+        this.closeTimeoutUnit = closeTimeoutUnit;
     }
 
     @VisibleForTesting
     public AsyncEventHandler(OptimizelyHttpClient httpClient, ExecutorService workerExecutor) {
         this.httpClient = httpClient;
         this.workerExecutor = workerExecutor;
+        this.closeTimeout = Long.MAX_VALUE;
+        this.closeTimeoutUnit = TimeUnit.MILLISECONDS;
     }
 
     @Override
@@ -136,6 +146,11 @@ public void shutdownAndAwaitTermination(long timeout, TimeUnit unit) {
         logger.info("event handler shutdown complete");
     }
 
+    @Override
+    public void close() {
+        shutdownAndAwaitTermination(closeTimeout, closeTimeoutUnit);
+    }
+
     //======== Helper classes ========//
 
     /**
@@ -205,4 +220,62 @@ public Void handleResponse(HttpResponse response) throws IOException {
             }
         }
     }
+
+    //======== Builder ========//
+
+    public static Builder builder() { return new Builder(); }
+
+    public static class Builder {
+
+        private int queueCapacity;
+        private int numWorkers;
+        private int maxTotalConnections = 200;
+        private int maxPerRoute = 20;
+        private int validateAfterInactivity = 5000;
+        private long closeTimeout = Long.MAX_VALUE;
+        private TimeUnit closeTimeoutUnit = TimeUnit.MILLISECONDS;
+
+        public Builder withQueueCapacity(int queueCapacity) {
+            this.queueCapacity = queueCapacity;
+            return this;
+        }
+
+        public Builder withNumWorkers(int numWorkers) {
+            this.numWorkers = numWorkers;
+            return this;
+        }
+
+        public Builder withMaxTotalConnections(int maxTotalConnections) {
+            this.maxTotalConnections = maxTotalConnections;
+            return this;
+        }
+
+        public Builder withMaxPerRoute(int maxPerRoute) {
+            this.maxPerRoute = maxPerRoute;
+            return this;
+        }
+
+        public Builder withValidateAfterInactivity(int validateAfterInactivity) {
+            this.validateAfterInactivity = validateAfterInactivity;
+            return this;
+        }
+
+        public Builder withCloseTimeout(long closeTimeout, TimeUnit unit) {
+            this.closeTimeout = closeTimeout;
+            this.closeTimeoutUnit = unit;
+            return this;
+        }
+
+        public AsyncEventHandler build() {
+            return new AsyncEventHandler(
+                queueCapacity,
+                numWorkers,
+                maxTotalConnections,
+                maxPerRoute,
+                validateAfterInactivity,
+                closeTimeout,
+                closeTimeoutUnit
+            );
+        }
+    }
 }

core-httpclient-impl/src/test/java/com/optimizely/ab/event/AsyncEventHandlerTest.java

@@ -65,7 +65,10 @@ public class AsyncEventHandlerTest {
     @Test
     public void testQueueCapacityPreconditionCheck() throws Exception {
         thrown.expect(IllegalArgumentException.class);
-        new AsyncEventHandler(-1, 1);
+        AsyncEventHandler.builder()
+            .withQueueCapacity(-1)
+            .withNumWorkers(-1)
+            .build();
     }
 
     @Test

java-quickstart/src/main/java/com/optimizely/Example.java

@@ -53,7 +53,11 @@ private void processVisitor(String userId, Map<String, String> attributes) {
     }
 
     public static void main(String[] args) throws InterruptedException {
-        EventHandler eventHandler = new AsyncEventHandler(100,2);
+        EventHandler eventHandler = AsyncEventHandler.builder()
+            .withQueueCapacity(100)
+            .withNumWorkers(2)
+            .build();
+
         HttpProjectConfigManager projectConfigManager = HttpProjectConfigManager.builder()
             .withSdkKey("BX9Y3bTa4YErpHZEMpAwHm")
             .withPollingInterval(1, TimeUnit.SECONDS)