michael@0: /* Any copyright is dedicated to the Public Domain.
michael@0:    http://creativecommons.org/publicdomain/zero/1.0/ */
michael@0: 
michael@0: package org.mozilla.gecko.background.testhelpers;
michael@0: 
michael@0: import java.util.concurrent.ArrayBlockingQueue;
michael@0: import java.util.concurrent.BlockingQueue;
michael@0: import java.util.concurrent.TimeUnit;
michael@0: 
michael@0: import org.mozilla.gecko.background.common.log.Logger;
michael@0: 
michael@0: /**
michael@0:  * Implements waiting for asynchronous test events.
michael@0:  *
michael@0:  * Call WaitHelper.getTestWaiter() to get the unique instance.
michael@0:  *
michael@0:  * Call performWait(runnable) to execute runnable synchronously.
michael@0:  * runnable *must* call performNotify() on all exit paths to signal to
michael@0:  * the TestWaiter that the runnable has completed.
michael@0:  *
michael@0:  * @author rnewman
michael@0:  * @author nalexander
michael@0:  */
michael@0: public class WaitHelper {
michael@0: 
michael@0:   public static final String LOG_TAG = "WaitHelper";
michael@0: 
michael@0:   public static class Result {
michael@0:     public Throwable error;
michael@0:     public Result() {
michael@0:       error = null;
michael@0:     }
michael@0: 
michael@0:     public Result(Throwable error) {
michael@0:       this.error = error;
michael@0:     }
michael@0:   }
michael@0: 
michael@0:   public static abstract class WaitHelperError extends Error {
michael@0:     private static final long serialVersionUID = 7074690961681883619L;
michael@0:   }
michael@0: 
michael@0:   /**
michael@0:    * Immutable.
michael@0:    *
michael@0:    * @author rnewman
michael@0:    */
michael@0:   public static class TimeoutError extends WaitHelperError {
michael@0:     private static final long serialVersionUID = 8591672555848651736L;
michael@0:     public final int waitTimeInMillis;
michael@0: 
michael@0:     public TimeoutError(int waitTimeInMillis) {
michael@0:       this.waitTimeInMillis = waitTimeInMillis;
michael@0:     }
michael@0:   }
michael@0: 
michael@0:   public static class MultipleNotificationsError extends WaitHelperError {
michael@0:     private static final long serialVersionUID = -9072736521571635495L;
michael@0:   }
michael@0: 
michael@0:   public static class InterruptedError extends WaitHelperError {
michael@0:     private static final long serialVersionUID = 8383948170038639308L;
michael@0:   }
michael@0: 
michael@0:   public static class InnerError extends WaitHelperError {
michael@0:     private static final long serialVersionUID = 3008502618576773778L;
michael@0:     public Throwable innerError;
michael@0: 
michael@0:     public InnerError(Throwable e) {
michael@0:       innerError = e;
michael@0:       if (e != null) {
michael@0:         // Eclipse prints the stack trace of the cause.
michael@0:         this.initCause(e);
michael@0:       }
michael@0:     }
michael@0:   }
michael@0: 
michael@0:   public BlockingQueue<Result> queue = new ArrayBlockingQueue<Result>(1);
michael@0: 
michael@0:   /**
michael@0:    * How long performWait should wait for, in milliseconds, with the
michael@0:    * convention that a negative value means "wait forever".
michael@0:    */
michael@0:   public static int defaultWaitTimeoutInMillis = -1;
michael@0: 
michael@0:   public void performWait(Runnable action) throws WaitHelperError {
michael@0:     this.performWait(defaultWaitTimeoutInMillis, action);
michael@0:   }
michael@0: 
michael@0:   public void performWait(int waitTimeoutInMillis, Runnable action) throws WaitHelperError {
michael@0:     Logger.debug(LOG_TAG, "performWait called.");
michael@0: 
michael@0:     Result result = null;
michael@0: 
michael@0:     try {
michael@0:       if (action != null) {
michael@0:         try {
michael@0:           action.run();
michael@0:           Logger.debug(LOG_TAG, "Action done.");
michael@0:         } catch (Exception ex) {
michael@0:           Logger.debug(LOG_TAG, "Performing action threw: " + ex.getMessage());
michael@0:           throw new InnerError(ex);
michael@0:         }
michael@0:       }
michael@0: 
michael@0:       if (waitTimeoutInMillis < 0) {
michael@0:         result = queue.take();
michael@0:       } else {
michael@0:         result = queue.poll(waitTimeoutInMillis, TimeUnit.MILLISECONDS);
michael@0:       }
michael@0:       Logger.debug(LOG_TAG, "Got result from queue: " + result);
michael@0:     } catch (InterruptedException e) {
michael@0:       // We were interrupted.
michael@0:       Logger.debug(LOG_TAG, "performNotify interrupted with InterruptedException " + e);
michael@0:       final InterruptedError interruptedError = new InterruptedError();
michael@0:       interruptedError.initCause(e);
michael@0:       throw interruptedError;
michael@0:     }
michael@0: 
michael@0:     if (result == null) {
michael@0:       // We timed out.
michael@0:       throw new TimeoutError(waitTimeoutInMillis);
michael@0:     } else if (result.error != null) {
michael@0:       Logger.debug(LOG_TAG, "Notified with error: " + result.error.getMessage());
michael@0: 
michael@0:       // Rethrow any assertion with which we were notified.
michael@0:       InnerError innerError = new InnerError(result.error);
michael@0:       throw innerError;
michael@0:     }
michael@0:     // Success!
michael@0:   }
michael@0: 
michael@0:   public void performNotify(final Throwable e) {
michael@0:     if (e != null) {
michael@0:       Logger.debug(LOG_TAG, "performNotify called with Throwable: " + e.getMessage());
michael@0:     } else {
michael@0:       Logger.debug(LOG_TAG, "performNotify called.");
michael@0:     }
michael@0: 
michael@0:     if (!queue.offer(new Result(e))) {
michael@0:       // This could happen if performNotify is called multiple times (which is an error).
michael@0:       throw new MultipleNotificationsError();
michael@0:     }
michael@0:   }
michael@0: 
michael@0:   public void performNotify() {
michael@0:     this.performNotify(null);
michael@0:   }
michael@0: 
michael@0:   public static Runnable onThreadRunnable(final Runnable r) {
michael@0:     return new Runnable() {
michael@0:       @Override
michael@0:       public void run() {
michael@0:         new Thread(r).start();
michael@0:       }
michael@0:     };
michael@0:   }
michael@0: 
michael@0:   private static WaitHelper singleWaiter = new WaitHelper();
michael@0:   public static WaitHelper getTestWaiter() {
michael@0:     return singleWaiter;
michael@0:   }
michael@0: 
michael@0:   public static void resetTestWaiter() {
michael@0:     singleWaiter = new WaitHelper();
michael@0:   }
michael@0: 
michael@0:   public boolean isIdle() {
michael@0:     return queue.isEmpty();
michael@0:   }
michael@0: }