Handle some uncaught runtime errors, fix race condition

2 files changed, 86 insertions, 17 deletions

diff --git a/api/src/main/java/org/openslx/taskmanager/api/AbstractTask.java b/api/src/main/java/org/openslx/taskmanager/api/AbstractTask.java
index 271a8bd..b850c2c 100644
--- a/api/src/main/java/org/openslx/taskmanager/api/AbstractTask.java
+++ b/api/src/main/java/org/openslx/taskmanager/api/AbstractTask.java
@@ -67,6 +67,11 @@ public abstract class AbstractTask implements Runnable
 	 * work when we're done.
 	 */
 	private volatile FinishCallback finishCallback = null;
+	
+	/**
+	 * Set to true as soon as we try to start this task using the thread pool executor.
+	 */
+	private volatile boolean triedToStart = false;
 
 	/**
 	 * Default constructor which should not be overridden
@@ -252,13 +257,22 @@ public abstract class AbstractTask implements Runnable
 	 */
 	public final boolean canStart()
 	{
-		if ( !this.initDone || this.id == null || this.getStatus().getStatusCode() != StatusCode.TASK_WAITING ) {
+		if ( this.triedToStart || !this.initDone || this.id == null || this.getStatus().getStatusCode() != StatusCode.TASK_WAITING ) {
 			return false;
 		}
 		if ( this.parent == null )
 			return true;
 		return parent.getStatusCode() != StatusCode.TASK_WAITING && parent.getStatusCode() != StatusCode.TASK_PROCESSING;
 	}
+	
+	/**
+	 * Mark this task as being started to prevent a race condition where
+	 * the task would be submitted to the thread pool more than once.
+	 */
+	public final void markAsStarting()
+	{
+		this.triedToStart = true;
+	}
 
 	/**
 	 * Checks whether this task can be removed from the task manager.
@@ -291,7 +305,7 @@ public abstract class AbstractTask implements Runnable
 		try {
 			ret = execute();
 		} catch ( Throwable t ) {
-			LOG.warn( "Task " + this.getClass().getSimpleName() + " failed with uncaught exception: " + t.toString() );
+			LOG.warn( "Task " + this.getClass().getSimpleName() + " failed with uncaught exception", t );
 			ret = false;
 		}
 		if ( ret ) {
diff --git a/api/src/main/java/org/openslx/taskmanager/api/SystemCommandTask.java b/api/src/main/java/org/openslx/taskmanager/api/SystemCommandTask.java
index ed47336..d5a3b64 100644
--- a/api/src/main/java/org/openslx/taskmanager/api/SystemCommandTask.java
+++ b/api/src/main/java/org/openslx/taskmanager/api/SystemCommandTask.java
@@ -17,9 +17,22 @@ public abstract class SystemCommandTask extends AbstractTask
 
 	private Process process = null;
 
+	protected int timeoutSeconds = 0;
+
 	@Override
 	protected final boolean execute()
 	{
+		try {
+			return execInternal();
+		} catch ( Exception e ) {
+			log.warn( "Unexpected exception when executing " + getId() + ": " + e.toString() );
+			processStdErrInternal( e.toString() );
+			return processEnded( -3 );
+		}
+	}
+
+	private final boolean execInternal()
+	{
 		command = initCommandLine();
 		if ( command == null || command.length == 0 ) {
 			return processEnded( -1 );
@@ -31,7 +44,13 @@ public abstract class SystemCommandTask extends AbstractTask
 		try {
 
 			// Create process
-			process = pb.start();
+			try {
+				process = pb.start();
+			} catch ( Exception e ) {
+				log.warn( "Process of task " + getId() + " died." );
+				processStdErrInternal( e.toString() );
+				return processEnded( -2 );
+			}
 			final Process p = process;
 			processStarted();
 			p.getOutputStream();
@@ -46,10 +65,11 @@ public abstract class SystemCommandTask extends AbstractTask
 						String line;
 						while ( ( line = reader.readLine() ) != null ) {
 							synchronized ( p ) {
-								processStdOut( line );
+								processStdOutInternal( line );
 							}
 						}
 					} catch ( Exception e ) {
+						e.printStackTrace();
 					}
 				}
 			} );
@@ -63,10 +83,11 @@ public abstract class SystemCommandTask extends AbstractTask
 						String line;
 						while ( ( line = reader.readLine() ) != null ) {
 							synchronized ( p ) {
-								processStdErr( line );
+								processStdErrInternal( line );
 							}
 						}
 					} catch ( Exception e ) {
+						e.printStackTrace();
 					}
 				}
 			} );
@@ -75,7 +96,30 @@ public abstract class SystemCommandTask extends AbstractTask
 			stderr.start();
 
 			// Wait for everything
-			process.waitFor();
+			int retval = -1;
+			if ( this.timeoutSeconds <= 0 ) {
+				retval = process.waitFor();
+			} else {
+				int togo = timeoutSeconds * 10;
+				while ( togo-- > 0 ) {
+					try {
+						retval = process.exitValue();
+						break;
+					} catch ( IllegalThreadStateException e1 ) {
+						// Still running....
+						try {
+							Thread.sleep( 100 );
+						} catch ( Exception e2 ) {
+							// Bummer....
+						}
+					}
+				}
+			}
+			try {
+				stdout.join( 500 );
+				stderr.join( 500 );
+			} catch ( Throwable t ) {
+			}
 			try {
 				process.getErrorStream().close();
 			} catch ( Throwable t ) {
@@ -84,22 +128,15 @@ public abstract class SystemCommandTask extends AbstractTask
 				process.getOutputStream().close();
 			} catch ( Throwable t ) {
 			}
-			stdout.join( 2000 );
-			stderr.join( 2000 );
 
-			return processEnded( process.exitValue() );
+			synchronized ( p ) {
+				return processEnded( retval );
+			}
 
-		} catch ( IOException e ) {
-			log.warn( "Process of task " + getId() + " died." );
-			processStdErr( e.toString() );
-			return processEnded( -2 );
 		} catch ( InterruptedException e ) {
+			processEnded( -4 );
 			Thread.currentThread().interrupt();
 			return false;
-		} catch ( Exception e ) {
-			log.warn( "Unexpected exception when executing " + getId() + ": " + e.toString() );
-			processStdErr( e.toString() );
-			return processEnded( -3 );
 		} finally {
 			if ( process != null )
 				process.destroy();
@@ -134,6 +171,24 @@ public abstract class SystemCommandTask extends AbstractTask
 		return toStdIn( text.getBytes( StandardCharsets.UTF_8 ) );
 	}
 
+	private final void processStdOutInternal( String line )
+	{
+		try {
+			processStdOut( line );
+		} catch ( Throwable t ) {
+			log.warn( "processStdOut failed", t );
+		}
+	}
+
+	private final void processStdErrInternal( String line )
+	{
+		try {
+			processStdErr( line );
+		} catch ( Throwable t ) {
+			log.warn( "processStdErr failed", t );
+		}
+	}
+
 	/**
 	 * Called to get the command line. Each argument should be a separate array
 	 * element. Returning null means the task should not run (as the arguments