Capture System out/err when progress is reported.

Author: fniephaus

substratevm/src/com.oracle.svm.hosted/src/com/oracle/svm/hosted/reporting/ProgressReporter.java

@@ -24,7 +24,9 @@
  */
 package com.oracle.svm.hosted.reporting;
 
+import java.io.ByteArrayOutputStream;
 import java.io.File;
+import java.io.PrintStream;
 import java.io.PrintWriter;
 import java.lang.management.GarbageCollectorMXBean;
 import java.lang.management.ManagementFactory;
@@ -95,6 +97,11 @@ public class ProgressReporter {
     private final boolean showLinks;
     private final ScheduledExecutorService executor = Executors.newSingleThreadScheduledExecutor();
 
+    private final PrintStream systemOut = System.out;
+    private final PrintStream systemErr = System.err;
+    private final ByteArrayOutputStream outBuffer = new ByteArrayOutputStream();
+    private final ByteArrayOutputStream errBuffer = new ByteArrayOutputStream();
+
     private ScheduledFuture<?> periodicPrintingTask;
     private int periodicPrintingTaskPeriodSeconds = 1;
 
@@ -150,7 +157,7 @@ public ProgressReporter(OptionValues options) {
             linePrinter = new ColorfulLinePrinter(enableProgress);
             /* Add a shutdown hook to reset the ANSI mode. */
             try {
-                Runtime.getRuntime().addShutdownHook(new Thread(ProgressReporter::resetANSIMode));
+                Runtime.getRuntime().addShutdownHook(new Thread(this::resetANSIMode));
             } catch (IllegalStateException e) {
                 /* If the VM is already shutting down, we do not need to register shutdownHook. */
             }
@@ -522,11 +529,17 @@ private void printProgressStart() {
         linePrinter.a(stringFilledWith(PROGRESS_BAR_START - numStageChars, " ")).dim().a("[");
         numStageChars = PROGRESS_BAR_START + 1; /* +1 for [ */
         linePrinter.flush();
+        if (isEnabled) {
+            installStdOutErrBuffers();
+        }
     }
 
     private void printProgressEnd() {
         linePrinter.a("]").reset().flush();
         numStageChars++; // for ]
+        if (isEnabled) {
+            resetStdOutErrBuffers();
+        }
     }
 
     public void printStageProgress() {
@@ -558,6 +571,9 @@ private void printStageEnd(double totalTime) {
         String padding = stringFilledWith(Math.max(0, CHARACTERS_PER_LINE - numStageChars - suffix.length()), " ");
         linePrinter.a(padding).dim().a(suffix).reset().flushln(false);
         numStageChars = 0;
+        if (isEnabled) {
+            flushStdOutErrBuffers();
+        }
         if (SubstrateOptions.BuildOutputGCWarnings.getValue()) {
             checkForExcessiveGarbageCollection();
         }
@@ -581,14 +597,37 @@ private void checkForExcessiveGarbageCollection() {
         lastGCStats = currentGCStats;
     }
 
-    private static void resetANSIMode() {
-        System.out.print(ANSIColors.RESET);
+    private void installStdOutErrBuffers() {
+        System.setOut(new PrintStream(outBuffer));
+        System.setErr(new PrintStream(errBuffer));
+    }
+
+    private void resetStdOutErrBuffers() {
+        System.setOut(systemOut);
+        System.setErr(systemErr);
+    }
+
+    private void flushStdOutErrBuffers() {
+        flushStdIOBuffer(outBuffer, systemOut);
+        flushStdIOBuffer(errBuffer, systemErr);
+    }
+
+    private static void flushStdIOBuffer(ByteArrayOutputStream buffer, PrintStream target) {
+        if (buffer.size() > 0) {
+            target.print(buffer.toString());
+            target.flush();
+            buffer.reset();
+        }
     }
 
     /*
      * HELPERS
      */
 
+    private void resetANSIMode() {
+        systemOut.print(ANSIColors.RESET);
+    }
+
     private static String stringFilledWith(int size, String fill) {
         return new String(new char[size]).replace("\0", fill);
     }
@@ -786,7 +825,7 @@ private void flush() {
             if (printBuffer != null) {
                 textBuffer.forEach(printBuffer::append);
             } else {
-                textBuffer.forEach(System.out::print);
+                textBuffer.forEach(systemOut::print);
             }
             textBuffer.clear();
         }
@@ -798,7 +837,7 @@ private void printRaw(String text) {
             if (printBuffer != null) {
                 printBuffer.append(text);
             } else {
-                System.out.print(text);
+                systemOut.print(text);
             }
         }
 
@@ -811,15 +850,15 @@ private void flushln(boolean useOutputPrefix) {
                 return;
             }
             if (useOutputPrefix) {
-                System.out.print(outputPrefix);
+                systemOut.print(outputPrefix);
             }
             if (printBuffer != null) {
-                System.out.print(printBuffer.toString());
+                systemOut.print(printBuffer.toString());
                 printBuffer.setLength(0); // Clear buffer.
             }
-            textBuffer.forEach(System.out::print);
+            textBuffer.forEach(systemOut::print);
             textBuffer.clear();
-            System.out.println();
+            systemOut.println();
         }
 
         private void flushCenteredln() {