read stdout/stderr at the same time if error output is not being redirected

src/de/uni_passau/fim/seibt/gitwrapper/process/ProcessExecutor.java

@@ -2,17 +2,21 @@ package de.uni_passau.fim.seibt.gitwrapper.process;
 
 import java.io.File;
 import java.io.IOException;
-import java.nio.charset.StandardCharsets;
 import java.util.Collections;
 import java.util.LinkedList;
 import java.util.List;
 import java.util.Optional;
+import java.util.concurrent.ExecutionException;
+import java.util.concurrent.ExecutorService;
+import java.util.concurrent.Executors;
+import java.util.concurrent.Future;
 import java.util.logging.Level;
 import java.util.logging.Logger;
 
 import org.apache.commons.io.IOUtils;
 
 import static de.uni_passau.fim.seibt.gitwrapper.repo.GitWrapper.EXIT_FAIL;
+import static java.nio.charset.StandardCharsets.UTF_8;
 import static java.util.logging.Level.WARNING;
 
 /**
@@ -21,6 +25,7 @@ import static java.util.logging.Level.WARNING;
 public class ProcessExecutor {
 
     private static final Logger LOG = Logger.getLogger(ProcessExecutor.class.getCanonicalName());
+    private static final ExecutorService exService = Executors.newCachedThreadPool();
 
     /**
      * The result of a process execution.
@@ -78,8 +83,35 @@ public class ProcessExecutor {
         try {
             Process p = builder.start();
 
-            String stdOut = IOUtils.toString(p.getInputStream(), StandardCharsets.UTF_8).trim();
-            String stdErr = IOUtils.toString(p.getErrorStream(), StandardCharsets.UTF_8).trim();
+            String stdOut;
+            String stdErr;
+
+            if (builder.redirectErrorStream()) {
+                stdOut = IOUtils.toString(p.getInputStream(), UTF_8).trim();
+                stdErr = IOUtils.toString(p.getErrorStream(), UTF_8).trim();
+            } else {
+                Future<String> outF = exService.submit(() -> IOUtils.toString(p.getInputStream(), UTF_8).trim());
+                Future<String> errF = exService.submit(() -> IOUtils.toString(p.getErrorStream(), UTF_8).trim());
+
+                try {
+                    stdOut = outF.get();
+                    stdErr = errF.get();
+                } catch (InterruptedException e) {
+                    LOG.log(WARNING, e, () -> String.format("Interrupted while waiting for '%s' to finish.", cmd));
+
+                    outF.cancel(true);
+                    errF.cancel(true);
+                    p.destroyForcibly();
+                    return Optional.empty();
+                } catch (ExecutionException e) {
+                    LOG.log(WARNING, e, () -> String.format("Exception while reading the output of '%s'.", cmd));
+
+                    outF.cancel(true);
+                    errF.cancel(true);
+                    p.destroyForcibly();
+                    return Optional.empty();
+                }
+            }
 
             IOUtils.closeQuietly(p.getInputStream());
             IOUtils.closeQuietly(p.getErrorStream());
@@ -93,7 +125,7 @@ public class ProcessExecutor {
                 LOG.log(WARNING, e, () -> String.format("Interrupted while waiting for '%s' to finish.", cmd));
 
                 p.destroyForcibly();
-                exitCode = EXIT_FAIL;
+                return Optional.empty();
             }
 
             ExecRes res = new ExecRes(exitCode, stdOut, stdErr);