From 082758c1be3b8624ce529d1c4fa8afa976781bb3 Mon Sep 17 00:00:00 2001
From: Robert von Burg <eitch@eitchnet.ch>
Date: Fri, 21 Feb 2020 16:24:12 +0100
Subject: [PATCH] [New] Added ExecutorPool for easier ExecutorService pool
 management

---
 .../java/li/strolch/utils/ExecutorPool.java   | 61 +++++++++++++++++++
 1 file changed, 61 insertions(+)
 create mode 100644 li.strolch.utils/src/main/java/li/strolch/utils/ExecutorPool.java

diff --git a/li.strolch.utils/src/main/java/li/strolch/utils/ExecutorPool.java b/li.strolch.utils/src/main/java/li/strolch/utils/ExecutorPool.java
new file mode 100644
index 000000000..a7e3fa405
--- /dev/null
+++ b/li.strolch.utils/src/main/java/li/strolch/utils/ExecutorPool.java
@@ -0,0 +1,61 @@
+package li.strolch.utils;
+
+import static java.util.concurrent.Executors.*;
+
+import java.util.Collections;
+import java.util.HashMap;
+import java.util.Map;
+import java.util.concurrent.ExecutorService;
+import java.util.concurrent.ScheduledExecutorService;
+import java.util.concurrent.TimeUnit;
+
+import li.strolch.utils.dbc.DBC;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+public class ExecutorPool {
+
+	private static final Logger logger = LoggerFactory.getLogger(ExecutorPool.class);
+
+	private Map<String, ExecutorService> executors;
+
+	public ExecutorPool() {
+		this.executors = Collections.synchronizedMap(new HashMap<>());
+	}
+
+	public ExecutorService getExecutor(String poolName) {
+		DBC.PRE.assertNotEmpty("poolName must be set!", poolName);
+		return this.executors.computeIfAbsent(poolName, p -> newCachedThreadPool(new NamedThreadPoolFactory(p)));
+	}
+
+	public ExecutorService getSingleThreadExecutor(String poolName) {
+		DBC.PRE.assertNotEmpty("poolName must be set!", poolName);
+		return this.executors.computeIfAbsent(poolName, p -> newSingleThreadExecutor(new NamedThreadPoolFactory(p)));
+	}
+
+	public ScheduledExecutorService getScheduledExecutor(String poolName) {
+		DBC.PRE.assertNotEmpty("poolName must be set!", poolName);
+		return (ScheduledExecutorService) this.executors
+				.computeIfAbsent(poolName, p -> newScheduledThreadPool(4, new NamedThreadPoolFactory(p)));
+	}
+
+	public void destroy() {
+
+		for (String poolName : this.executors.keySet()) {
+			logger.info("Shutting down executor pool " + poolName);
+			ExecutorService executor = this.executors.get(poolName);
+
+			try {
+				executor.shutdown();
+				executor.awaitTermination(5, TimeUnit.SECONDS);
+			} catch (InterruptedException e) {
+				logger.error("Was interrupted while shutting down tasks");
+			} finally {
+				if (!executor.isTerminated()) {
+					logger.error("Tasks not stopped after " + 5 + "s. Shutting down now.");
+					executor.shutdownNow();
+				}
+			}
+		}
+	}
+}