Add build failure notification support

src/main/java/org/codeaholics/tools/build/pant/DependencyGraphEntry.java

@@ -19,6 +19,7 @@
 import java.util.HashSet;
 import java.util.Set;
 
+import org.apache.tools.ant.BuildException;
 import org.apache.tools.ant.Target;
 
 public class DependencyGraphEntry implements Runnable {
@@ -87,6 +88,8 @@ public void run() {
         executionNotifier.notifyStarting(this);
         try {
             targetExecutor.executeTarget(target);
+        } catch (BuildException e) {
+            executionNotifier.notifyException(this, e);
         } finally {
             executionNotifier.notifyComplete(this);
         }

src/main/java/org/codeaholics/tools/build/pant/ParallelExecutor.java

@@ -45,6 +45,8 @@ public class ParallelExecutor implements Executor {
     private AntWrapper antWrapper = new AntWrapperImpl();
     private ExecutorService executorService;
 
+    private final List<BuildException> buildExceptions = new LinkedList<BuildException>();
+
     private int queued;
     @SuppressWarnings("unused")
     private int started;
@@ -112,6 +114,25 @@ private void executeTarget(final Target target, final Map<String, Target> target
         } catch (final InterruptedException e) {
             // ignore
         }
+
+        // Check for any exceptions that were thrown from the executorService
+        if (buildExceptions.size() > 1) {
+            // Combine the multiple exceptions into a new BuildException so all the errors are propagated to the user
+            String msg = "\n" + buildExceptions.size() + " failures occurred while building:";
+
+            int i = 0;
+            for (BuildException e : buildExceptions) {
+                i += 1;
+                msg += "\nFailure " + i + ":\n" + e + "\n";
+            }
+
+            throw new BuildException(msg);
+        } else {
+            // 0 or 1 exceptions, if 1 exists then just throw it
+            for (BuildException e : buildExceptions) {
+                throw e;
+            }
+        }
     }
 
     private int getNumberOfThreads(final Project project) {
@@ -171,6 +192,12 @@ public synchronized void notifyComplete(final DependencyGraphEntry dependencyGra
                     executorService.shutdown();
                 }
             }
+
+            @Override
+            public synchronized void notifyException(final DependencyGraphEntry dependencyGraphEntry, BuildException e) {
+                buildExceptions.add(e);
+                executorService.shutdown();
+            }
         };
     }
 
@@ -235,4 +262,4 @@ private void verifyPrePhaseTargets(final Map<String, Target> targetsByName) {
     public Executor getSubProjectExecutor() {
         return SUB_EXECUTOR;
     }
-}
+}

src/main/java/org/codeaholics/tools/build/pant/TargetExecutionNotifier.java

@@ -16,7 +16,10 @@
  *   limitations under the License.
  */
 
+import org.apache.tools.ant.BuildException;
+
 public interface TargetExecutionNotifier {
     public void notifyStarting(DependencyGraphEntry dependencyGraphEntry);
     public void notifyComplete(DependencyGraphEntry dependencyGraphEntry);
+    public void notifyException(DependencyGraphEntry dependencyGraphEntry, BuildException e);
 }