Changed prompt interruption contract

Signed-off-by: Emmanuel Bigeon <emmanuel@bigeon.fr>

gclc/src/main/java/net/bigeon/gclc/manager/ConsoleInput.java

@@ -94,8 +94,7 @@ public interface ConsoleInput extends AutoCloseable {
     /** Indicate to the input that is should interrompt the prompting, if possible.
      * <p>
      * The pending {@link #prompt()} or {@link #prompt(String)} operations should
-     * return immediatly. However the returned value can be anything (from the
-     * partial prompt content to an empty string or even a null pointer). */
+     * return immediately by throwing an InterruptedIOException. */
     void interruptPrompt();
 
     /** Test if the input is closed.

gclc/src/main/java/net/bigeon/gclc/utils/ReadingRunnable.java

@@ -111,6 +111,7 @@ public final class ReadingRunnable implements Runnable {
     private final Map<String, Object> messageBlocker     = new ConcurrentHashMap<>();
     /** The lock. */
     private final Object              messageBlockerLock = new Object();
+    private boolean                   interrupting       = false;
     /** Create a reading runnable.
      *
      * @param reader the input to read from */
@@ -146,8 +147,7 @@ public final class ReadingRunnable implements Runnable {
     public String getMessage() throws IOException {
         synchronized (lock) {
             if (!messages.isEmpty()) {
-                notifyMessage(messages.peek());
-                return messages.poll();
+                return pollMessage();
             }
             if (!running) {
                 throw new IOException(CLOSED_PIPE);
@@ -156,8 +156,7 @@ public final class ReadingRunnable implements Runnable {
             waitMessage(TIMEOUT);
             LOGGER.log(Level.FINEST, "Polled: {0}", messages.peek()); //$NON-NLS-1$
             waiting = false;
-            notifyMessage(messages.peek());
-            return messages.poll();
+            return pollMessage();
         }
     }
 
@@ -169,8 +168,7 @@ public final class ReadingRunnable implements Runnable {
     public String getNextMessage(final long timeout) throws IOException {
         synchronized (lock) {
             if (!messages.isEmpty()) {
-                notifyMessage(messages.peek());
-                return messages.poll();
+                return pollMessage();
             }
             if (!running) {
                 throw new IOException(CLOSED_PIPE);
@@ -181,10 +179,18 @@ public final class ReadingRunnable implements Runnable {
             if (messages.isEmpty()) {
                 return null;
             }
-            notifyMessage(messages.peek());
-            return messages.poll();
+            return pollMessage();
         }
     }
+
+    private String pollMessage() throws InterruptedIOException {
+        final String msg = messages.poll();
+        if (msg.isEmpty() && interrupting) {
+            throw new InterruptedIOException();
+        }
+        notifyMessage(msg);
+        return msg;
+    }
     
     /** Wait for a message to be delivered.
      * 
@@ -221,7 +227,8 @@ public final class ReadingRunnable implements Runnable {
     public void interrupt() {
         synchronized (lock) {
             if (waiting) {
-                messages.offer(""); //$NON-NLS-1$
+                messages.offer("");
+                interrupting = true;
                 lock.notifyAll();
             }
         }

gclc/src/test/java/net/bigeon/gclc/manager/ReadingRunnableTest.java

@@ -80,6 +80,7 @@ import java.io.BufferedWriter;
 import java.io.IOException;
 import java.io.InputStream;
 import java.io.InputStreamReader;
+import java.io.InterruptedIOException;
 import java.io.OutputStreamWriter;
 import java.io.PipedInputStream;
 import java.io.PipedOutputStream;
@@ -90,6 +91,9 @@ import org.junit.Before;
 import org.junit.Test;
 
 import net.bigeon.gclc.utils.ReadingRunnable;
+import net.bigeon.test.junitmt.FunctionalTestRunnable;
+import net.bigeon.test.junitmt.TestFunction;
+import net.bigeon.test.junitmt.ThreadTest;
 
 /**
  * <p>
@@ -198,9 +202,11 @@ public class ReadingRunnableTest {
     public final void testGetPendingMessages() throws IOException, InterruptedException {
 
         final PipedOutputStream out = new PipedOutputStream();
-        final BufferedReader reader = new BufferedReader(new InputStreamReader(new PipedInputStream(out), StandardCharsets.UTF_8));
+        final BufferedReader reader = new BufferedReader(
+                new InputStreamReader(new PipedInputStream(out), StandardCharsets.UTF_8));
         final ReadingRunnable runnable = new ReadingRunnable(reader);
-        final BufferedWriter writer = new BufferedWriter(new OutputStreamWriter(out, StandardCharsets.UTF_8));
+        final BufferedWriter writer = new BufferedWriter(
+                new OutputStreamWriter(out, StandardCharsets.UTF_8));
         writer.write("one");
         writer.newLine();
         writer.write("two");
@@ -222,4 +228,30 @@ public class ReadingRunnableTest {
             // ok
         }
     }
+
+    @Test
+    public void testInterruption() throws IOException, InterruptedException {
+        final PipedOutputStream out = new PipedOutputStream();
+        final BufferedReader reader = new BufferedReader(
+                new InputStreamReader(new PipedInputStream(out), StandardCharsets.UTF_8));
+        final ReadingRunnable runnable = new ReadingRunnable(reader);
+
+        final FunctionalTestRunnable test = new FunctionalTestRunnable(
+                new TestFunction() {
+                    @Override
+                    public void apply() throws IOException {
+                        try {
+                            runnable.getMessage();
+                            fail("Message interruption should cause an exception");
+                        } catch (final InterruptedIOException e) {
+                            // ok
+                        }
+                    }
+                });
+        final Thread th = new Thread(test, "Prompt wait");
+        th.start();
+        th.join(200);
+        runnable.interrupt();
+        ThreadTest.assertRuns(th, test);
+    }
 }