[MSHARED-1072] Poll data from input stream

slawekjaranowski · slawekjaranowski · commit 1c264bae8d9c · 2023-05-08T08:36:50.000+02:00
Input stream can be a System.in - all read will be blocked
We need read data in no blocking mode
diff --git a/src/main/java/org/apache/maven/shared/utils/cli/CommandLineUtils.java b/src/main/java/org/apache/maven/shared/utils/cli/CommandLineUtils.java
@@ -250,13 +250,13 @@ public void run() {
 
             @Override
             public Integer call() throws CommandLineException {
-                StreamFeeder inputFeeder = null;
+                StreamPollFeeder inputFeeder = null;
                 StreamPumper outputPumper = null;
                 StreamPumper errorPumper = null;
                 try {
                     if (systemIn != null) {
-                        inputFeeder = new StreamFeeder(systemIn, p.getOutputStream());
-                        inputFeeder.setName("StreamFeeder-systemIn");
+                        inputFeeder = new StreamPollFeeder(systemIn, p.getOutputStream());
+                        inputFeeder.setName("StreamPollFeeder-systemIn");
                         inputFeeder.start();
                     }
 
diff --git a/src/main/java/org/apache/maven/shared/utils/cli/StreamPollFeeder.java b/src/main/java/org/apache/maven/shared/utils/cli/StreamPollFeeder.java
@@ -24,51 +24,64 @@
 import java.util.Objects;
 
 /**
- * Read from an InputStream and write the output to an OutputStream.
+ * Poll InputStream for available data and write the output to an OutputStream.
  *
  * @author <a href="mailto:trygvis@inamo.no">Trygve Laugst&oslash;l</a>
  */
-class StreamFeeder extends Thread {
+class StreamPollFeeder extends Thread {
 
-    private final InputStream input;
+    public static final int BUF_LEN = 80;
 
+    private final InputStream input;
     private final OutputStream output;
 
     private Throwable exception;
-    private boolean done;
 
+    private boolean done;
     private final Object lock = new Object();
 
     /**
-     * Create a new StreamFeeder
+     * Create a new StreamPollFeeder
      *
      * @param input  Stream to read from
      * @param output Stream to write to
      */
-    StreamFeeder(InputStream input, OutputStream output) {
+    StreamPollFeeder(InputStream input, OutputStream output) {
         this.input = Objects.requireNonNull(input);
         this.output = Objects.requireNonNull(output);
         this.done = false;
     }
 
     @Override
-    @SuppressWarnings("checkstyle:innerassignment")
     public void run() {
+
+        byte[] buf = new byte[BUF_LEN];
+
         try {
-            for (int data; !isInterrupted() && (data = input.read()) != -1; ) {
-                output.write(data);
+            while (!done) {
+                if (input.available() > 0) {
+                    int i = input.read(buf);
+                    if (i > 0) {
+                        output.write(buf, 0, i);
+                        output.flush();
+                    } else {
+                        done = true;
+                    }
+                } else {
+                    synchronized (lock) {
+                        if (!done) {
+                            lock.wait(100);
+                        }
+                    }
+                }
             }
-            output.flush();
         } catch (IOException e) {
             exception = e;
+        } catch (InterruptedException e) {
+            Thread.currentThread().interrupt();
         } finally {
             close();
         }
-
-        synchronized (lock) {
-            done = true;
-            lock.notifyAll();
-        }
     }
 
     private void close() {
@@ -89,15 +102,16 @@ public Throwable getException() {
     }
 
     public void waitUntilDone() {
-        this.interrupt();
+
         synchronized (lock) {
-            while (!done) {
-                try {
-                    lock.wait();
-                } catch (InterruptedException e) {
-                    Thread.currentThread().interrupt();
-                }
-            }
+            done = true;
+            lock.notifyAll();
+        }
+
+        try {
+            join();
+        } catch (InterruptedException e) {
+            Thread.currentThread().interrupt();
         }
     }
 }
diff --git a/src/test/java/org/apache/maven/shared/utils/cli/StreamFeederTest.java b/src/test/java/org/apache/maven/shared/utils/cli/StreamFeederTest.java
diff --git a/src/test/java/org/apache/maven/shared/utils/cli/StreamPollFeederTest.java b/src/test/java/org/apache/maven/shared/utils/cli/StreamPollFeederTest.java
@@ -0,0 +1,76 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied.  See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ */
+package org.apache.maven.shared.utils.cli;
+
+import java.io.ByteArrayInputStream;
+import java.io.ByteArrayOutputStream;
+import java.io.IOException;
+
+import org.junit.Test;
+
+import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertNull;
+
+public class StreamPollFeederTest {
+
+    @Test
+    public void waitUntilFeederDoneOnInputStream() throws Exception {
+
+        ByteArrayOutputStream outputStream = new ByteArrayOutputStream();
+        StreamPollFeeder streamPollFeeder = new StreamPollFeeder(System.in, outputStream);
+
+        // start thread
+        streamPollFeeder.start();
+
+        // wait a moment
+        Thread.sleep(100);
+
+        // wait until process finish
+        streamPollFeeder.waitUntilDone();
+        assertNull(streamPollFeeder.getException());
+    }
+
+    @Test
+    public void dataShouldBeCopied() throws InterruptedException, IOException {
+
+        StringBuilder TEST_DATA = new StringBuilder();
+        for (int i = 0; i < 100; i++) {
+            TEST_DATA.append("TestData");
+        }
+
+        ByteArrayInputStream inputStream =
+                new ByteArrayInputStream(TEST_DATA.toString().getBytes());
+        ByteArrayOutputStream outputStream = new ByteArrayOutputStream();
+
+        StreamPollFeeder streamPollFeeder = new StreamPollFeeder(inputStream, outputStream);
+
+        streamPollFeeder.start();
+
+        //  wait until all data from steam will be read
+        while (outputStream.size() < TEST_DATA.length()) {
+            Thread.sleep(100);
+        }
+
+        // wait until process finish
+        streamPollFeeder.waitUntilDone();
+        assertNull(streamPollFeeder.getException());
+
+        assertEquals(TEST_DATA.toString(), outputStream.toString());
+    }
+}
