Read stdout and stderr in separate threads

Integration tests use boltkit to start database and cluster.
Boltkit commands are invoked using Process API. Invocations
sometimes hang on MacOS.

This commit improves handling of stdout and stderr streams.
Both are now read in parallel with waiting for command to
finish. This prevents output bufferes from overflowing and
might fix the hanging.

Author: lutovich

driver/src/test/java/org/neo4j/driver/v1/util/cc/CommandLineUtil.java

@@ -23,14 +23,23 @@
 import java.io.InputStream;
 import java.io.InputStreamReader;
 import java.util.List;
+import java.util.concurrent.Callable;
+import java.util.concurrent.ExecutorService;
+import java.util.concurrent.Executors;
+import java.util.concurrent.Future;
 
+import org.neo4j.driver.v1.util.DaemonThreadFactory;
 import org.neo4j.driver.v1.util.ProcessEnvConfigurator;
 
 import static java.lang.System.lineSeparator;
 import static java.util.Arrays.asList;
+import static java.util.concurrent.TimeUnit.MINUTES;
 
 public class CommandLineUtil
 {
+    private static final ExecutorService executor = Executors.newCachedThreadPool(
+            new DaemonThreadFactory( "command-line-thread-" ) );
+
     public static boolean boltKitAvailable()
     {
         try
@@ -59,8 +68,7 @@ public static String executeCommand( List<String> commands )
         catch ( InterruptedException e )
         {
             Thread.currentThread().interrupt();
-            throw new CommandLineException( "Interrupted while waiting for command " +
-                                            commands, e );
+            throw new CommandLineException( "Interrupted while waiting for command " + commands, e );
         }
     }
 
@@ -73,17 +81,31 @@ private static String executeAndGetStdOut( ProcessBuilder processBuilder )
             throws IOException, InterruptedException
     {
         Process process = processBuilder.start();
+        Future<String> stdOutFuture = read( process.getInputStream() );
+        Future<String> stdErrFuture = read( process.getErrorStream() );
         int exitCode = process.waitFor();
-        String stdOut = asString( process.getInputStream() );
-        String stdErr = asString( process.getErrorStream() );
+        String stdOut = get( stdOutFuture );
+        String stdErr = get( stdErrFuture );
         if ( exitCode != 0 )
         {
             throw new CommandLineException( "Non-zero exit code\nSTDOUT:\n" + stdOut + "\nSTDERR:\n" + stdErr );
         }
         return stdOut;
     }
 
-    private static String asString( InputStream input )
+    private static Future<String> read( final InputStream input )
+    {
+        return executor.submit( new Callable<String>()
+        {
+            @Override
+            public String call() throws Exception
+            {
+                return readToString( input );
+            }
+        } );
+    }
+
+    private static String readToString( InputStream input )
     {
         StringBuilder result = new StringBuilder();
         try ( BufferedReader reader = new BufferedReader( new InputStreamReader( input ) ) )
@@ -100,4 +122,16 @@ private static String asString( InputStream input )
         }
         return result.toString();
     }
+
+    private static <T> T get( Future<T> future )
+    {
+        try
+        {
+            return future.get( 10, MINUTES );
+        }
+        catch ( Exception e )
+        {
+            throw new RuntimeException( e );
+        }
+    }
 }