From 8c21d3ec1a6ab04e0011a7e988a3cdc8a8ae19ce Mon Sep 17 00:00:00 2001
From: Simon Rettberg
Date: Thu, 10 Dec 2020 13:51:44 +0100
Subject: [MountVmStore] Better handling of concurrent invocations

---
 src/main/java/org/openslx/satserver/util/Util.java | 13 ++++++++
 .../openslx/taskmanager/tasks/MountVmStore.java    | 37 ++++++++++++++++++----
 2 files changed, 44 insertions(+), 6 deletions(-)

(limited to 'src')

diff --git a/src/main/java/org/openslx/satserver/util/Util.java b/src/main/java/org/openslx/satserver/util/Util.java
index 55dc76b..262fd56 100644
--- a/src/main/java/org/openslx/satserver/util/Util.java
+++ b/src/main/java/org/openslx/satserver/util/Util.java
@@ -116,5 +116,18 @@ public class Util
 			return defaultValue;
 		}
 	}
+	
+	/**
+	 * Compare two strings for equality.
+	 * null and "" are not considered equal.
+	 */
+	public static boolean strcmp(String a, String b)
+	{
+		if ( a == null && b == null )
+			return true;
+		if ( a == null || b == null )
+			return false;
+		return a.equals( b );
+	}
 
 }
diff --git a/src/main/java/org/openslx/taskmanager/tasks/MountVmStore.java b/src/main/java/org/openslx/taskmanager/tasks/MountVmStore.java
index 2a46a10..d0530cc 100644
--- a/src/main/java/org/openslx/taskmanager/tasks/MountVmStore.java
+++ b/src/main/java/org/openslx/taskmanager/tasks/MountVmStore.java
@@ -1,7 +1,7 @@
 package org.openslx.taskmanager.tasks;
 
 import java.util.Map;
-import java.util.concurrent.atomic.AtomicBoolean;
+import java.util.concurrent.atomic.AtomicReference;
 
 import org.openslx.satserver.util.Constants;
 import org.openslx.satserver.util.Util;
@@ -26,7 +26,7 @@ public class MountVmStore extends SystemCommandTask
 
 	private Output status = new Output();
 	
-	private static AtomicBoolean isRunning = new AtomicBoolean();
+	private static AtomicReference<MountVmStore> isRunning = new AtomicReference<>();
 
 	@Override
 	protected boolean initTask()
@@ -47,9 +47,19 @@ public class MountVmStore extends SystemCommandTask
 	@Override
 	protected String[] initCommandLine()
 	{
-		if (!isRunning.compareAndSet( false, true )) {
-			status.addMessage("Another operation is already in progress.");
-			return null;
+		if ( !isRunning.compareAndSet( null, this ) ) {
+			MountVmStore current = isRunning.get();
+			if ( current != null ) {
+				if ( current.equals( this ) ) {
+					// Exactly the same options - return other ID
+					status.existingTask = current.getId();
+					status.addMessage( "Concurrent call with same options - see 'existingTask' field" );
+				} else {
+					// Different options to existing, active task
+					status.addMessage( "Another operation is already in progress." );
+				}
+				return null;
+			}
 		}
 		return new String[] {
 				"/usr/bin/sudo",
@@ -71,11 +81,25 @@ public class MountVmStore extends SystemCommandTask
 			environment.put( "TM_MOUNT_OPTIONS", this.opts );
 		}
 	}
+	
+	@Override
+	public boolean equals( Object obj )
+	{
+		if ( !(obj instanceof MountVmStore) )
+			return false;
+		MountVmStore o = (MountVmStore)obj;
+		return Util.strcmp( this.address, o.address )
+				&& Util.strcmp( this.type, o.type )
+				&& Util.strcmp( this.opts, o.opts )
+				&& Util.strcmp( this.username, o.username )
+				&& Util.strcmp( this.password, o.password )
+				&& this.localNfs == o.localNfs;
+	}
 
 	@Override
 	protected boolean processEnded( int exitCode )
 	{
-		isRunning.set( false );
+		isRunning.set( null );
 		if ( exitCode != 0 )
 			status.addMessage( "Failed with exit code " + exitCode );
 		status.exitCode = exitCode;
@@ -98,6 +122,7 @@ public class MountVmStore extends SystemCommandTask
 	{
 		public String messages = null;
 		public int exitCode = -111;
+		public String existingTask;
 
 		private void addMessage( String str )
 		{
-- 
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