Rework SpringBootApp cache

headless-services/commons/commons-boot-app-cli/src/main/java/org/springframework/ide/vscode/commons/boot/app/cli/SpringBootApp.java

@@ -12,6 +12,7 @@ package org.springframework.ide.vscode.commons.boot.app.cli;
 
 import java.io.File;
 import java.io.IOException;
+import java.time.Duration;
 import java.util.ArrayList;
 import java.util.Collection;
 import java.util.HashSet;
@@ -60,64 +61,22 @@ public class SpringBootApp {
 
 	private VirtualMachine vm;
 	private VirtualMachineDescriptor vmd;
-	private Supplier<String> jmxConnect;
 
-	private static final Cache<VirtualMachineDescriptor, String> pidToJmxConnectUrl = CacheBuilder.newBuilder().build();
-
-	private static Callable<Collection<SpringBootApp>> cached(Callable<Collection<SpringBootApp>> provider) {
-		LoadingCache<Object, CompletableFuture<Collection<SpringBootApp>>> cache = CacheBuilder.newBuilder()
-		.expireAfterWrite(500, TimeUnit.MILLISECONDS)
-		.removalListener(removalNotification -> {
-			 @SuppressWarnings("unchecked")
-			CompletableFuture<Collection<SpringBootApp>> removed = (CompletableFuture<Collection<SpringBootApp>>) removalNotification.getValue();
-			if (!removed.isCompletedExceptionally()) {
-				try {
-					Collection<SpringBootApp> apps = removed.get();
-					for (SpringBootApp springBootApp : apps) {
-						springBootApp.dispose();
-					}
-				} catch (Exception e) {
-					Log.log(e);
-				}
-			}
-		})
-		.build(new CacheLoader<Object, CompletableFuture<Collection<SpringBootApp>>>() {
-			@Override public CompletableFuture<Collection<SpringBootApp>> load(Object key) {
-				try {
-					return CompletableFuture.completedFuture(provider.call());
-				} catch (Throwable e) {
-					return Futures.error(e);
-				}
-			}
-		});
-		return () -> {
-			Object key = SpringBootApp.class; //This key really doesn't matter, as long as we use the same non-null object each time.
-			return cache.get(key).get();
-		};
-	}
-
-
-	private static Collection<SpringBootApp> fetchRunningJavaApps() throws Exception {
-		List<VirtualMachineDescriptor> list = VirtualMachine.list();
-		ImmutableList.Builder<SpringBootApp> apps = ImmutableList.builder();
-		for (VirtualMachineDescriptor vmd : list) {
-			apps.add(new SpringBootApp(vmd));
+	private final Supplier<String> jmxConnect = Suppliers.memoize(() -> {
+		try {
+			return vm.startLocalManagementAgent();
+		} catch (Exception e) {
+			Log.log(e);
+			return null;
 		}
+	});
 
-		// Invalidate part of pidToJmxConnectUrl cache to remove old processes
-		Set<VirtualMachineDescriptor> oldProcesses = new HashSet<>(pidToJmxConnectUrl.asMap().keySet());
-		oldProcesses.removeAll(list);
-		pidToJmxConnectUrl.invalidateAll(oldProcesses);
-
-		return apps.build();
-	}
+	private static SpringBootAppCache cache = new SpringBootAppCache();
 
 	public static Collection<SpringBootApp> getAllRunningJavaApps() throws Exception {
-		return cachedJavaAppsGetter.call();
+		return cache.getAllRunningJavaApps();
 	}
 
-	private static Callable<Collection<SpringBootApp>> cachedJavaAppsGetter = cached(SpringBootApp::fetchRunningJavaApps);
-
 	/**
 	 * @return Map that contains the boot apps, mapping the process ID -> boot app accessor object
 	 */
@@ -128,7 +87,6 @@ public class SpringBootApp {
 	public SpringBootApp(VirtualMachineDescriptor vmd) throws Exception {
 		this.vmd = vmd;
 		this.vm = VirtualMachine.attach(vmd);
-		this.jmxConnect = Suppliers.memoize(() -> getJmxConnectUrl());
 		System.err.println("SpringBootApp created: "+this);
 	}
 
@@ -140,17 +98,6 @@ public class SpringBootApp {
 		return vmd.displayName();
 	}
 
-	private String getJmxConnectUrl() {
-		try {
-			return pidToJmxConnectUrl.get(vmd, () -> {
-				return vm.startLocalManagementAgent();
-			});
-		} catch (ExecutionException e) {
-			Log.log(e);
-			return null;
-		}
-	}
-
 	public String getHost() throws Exception {
 		JMXServiceURL serviceUrl = new JMXServiceURL(jmxConnect.get());
 		return serviceUrl.getHost();

headless-services/commons/commons-boot-app-cli/src/main/java/org/springframework/ide/vscode/commons/boot/app/cli/SpringBootAppCache.java

@@ -0,0 +1,61 @@
+/*******************************************************************************
+ * Copyright (c) 2017 Pivotal, Inc.
+ * All rights reserved. This program and the accompanying materials
+ * are made available under the terms of the Eclipse Public License v1.0
+ * which accompanies this distribution, and is available at
+ * http://www.eclipse.org/legal/epl-v10.html
+ *
+ * Contributors:
+ *     Pivotal, Inc. - initial API and implementation
+ *******************************************************************************/
+package org.springframework.ide.vscode.commons.boot.app.cli;
+
+import java.time.Duration;
+import java.util.Collection;
+import java.util.HashSet;
+import java.util.List;
+
+import org.springframework.ide.vscode.commons.util.Log;
+
+import com.google.common.collect.ImmutableMap;
+import com.sun.tools.attach.VirtualMachine;
+import com.sun.tools.attach.VirtualMachineDescriptor;
+
+public class SpringBootAppCache {
+
+	private static final Duration EXPIRE_AFTER = Duration.ofMillis(500); //Limits rate at which we refresh list of apps
+	private long nextRefreshAfter = Long.MIN_VALUE;
+
+	private ImmutableMap<VirtualMachineDescriptor, SpringBootApp> apps = ImmutableMap.of();
+
+	public synchronized Collection<SpringBootApp> getAllRunningJavaApps() {
+		if (System.currentTimeMillis()>=nextRefreshAfter) {
+			refresh();
+		}
+		return apps.values();
+	}
+
+	private void refresh() {
+		List<VirtualMachineDescriptor> currentVms = VirtualMachine.list();
+		HashSet<VirtualMachineDescriptor> oldVms = new HashSet<>(apps.keySet());
+		ImmutableMap.Builder<VirtualMachineDescriptor, SpringBootApp> newApps = ImmutableMap.builder();
+		for (VirtualMachineDescriptor vm : currentVms) {
+			oldVms.remove(vm);
+			SpringBootApp existingApp = apps.get(vm);
+			if (existingApp!=null) {
+				newApps.put(vm, existingApp);
+			} else {
+				try {
+					newApps.put(vm, new SpringBootApp(vm));
+				} catch (Exception e) {
+					Log.log(e);
+				}
+			}
+		}
+		for (VirtualMachineDescriptor oldVm : oldVms) {
+			apps.get(oldVm).dispose();
+		}
+		apps = newApps.build();
+		nextRefreshAfter = System.currentTimeMillis() + EXPIRE_AFTER.toMillis();
+	}
+}