Set desugar-specific JVM flags from within the desugar binary

...not at the target level.

PiperOrigin-RevId: 742262901
Change-Id: Ia299df67a3e6cc289ba07969f81959cf26c9275a

Author: ted-xie

src/tools/java/com/google/devtools/build/android/r8/BUILD

@@ -85,11 +85,6 @@ java_binary(
         "-XX:TieredStopAtLevel=1",
         "-Xms8g",
         "-Xmx8g",
-        # b/172508621
-        "-Dcom.android.tools.r8.sortMethodsOnCfWriting",
-        "-Dcom.android.tools.r8.allowAllDesugaredInput",
-        "-Dcom.android.tools.r8.noCfMarkerForDesugaredCode",
-        "-Dcom.android.tools.r8.lambdaClassFieldsNotFinal",
     ],
     main_class = "com.google.devtools.build.android.r8.Desugar",
     visibility = [

src/tools/java/com/google/devtools/build/android/r8/Desugar.java

@@ -61,6 +61,16 @@ public class Desugar {
   private static final int NUMBER_OF_ENTRIES_PER_SHARD = 100000;
   private static final Logger logger = Logger.getLogger(Desugar.class.getName());
 
+  private static final Object mutex = new Object();
+
+  // See b/172508621
+  private static final ImmutableList<String> DESUGAR_JVM_FLAGS =
+      ImmutableList.of(
+          "com.android.tools.r8.sortMethodsOnCfWriting",
+          "com.android.tools.r8.allowAllDesugaredInput",
+          "com.android.tools.r8.noCfMarkerForDesugaredCode",
+          "com.android.tools.r8.lambdaClassFieldsNotFinal");
+
   /** Commandline options for {@link com.google.devtools.build.android.r8.Desugar}. */
   @Parameters(separators = "= ")
   public static class DesugarOptions {
@@ -584,10 +594,27 @@ private static void validateOptions(DesugarOptions options) {
 
   private static int processRequest(List<String> args, PrintStream diagnosticsHandlerPrintStream)
       throws Exception {
-    DesugarOptions options = parseCommandLineOptions(args.toArray(new String[0]));
-    validateOptions(options);
-    new Desugar(options, diagnosticsHandlerPrintStream).desugar();
-    return 0;
+    // Execute the desugar workload inside of an atomic mutex lock
+    // Since JVM flags are applied JVM-wide, we want to ensure that it's impossible for another
+    // Desugar workload to execute until after the JVM flags have already been reset.
+    synchronized (mutex) {
+      setDesugarJvmFlags();
+      int exitCode = 0;
+      try {
+        DesugarOptions options = parseCommandLineOptions(args.toArray(new String[0]));
+        validateOptions(options);
+        new Desugar(options, diagnosticsHandlerPrintStream).desugar();
+        exitCode = 0;
+      } catch (Exception e) {
+        diagnosticsHandlerPrintStream.println(e.getMessage());
+        e.printStackTrace();
+        exitCode = 1;
+      } finally {
+        unsetDesugarJvmFlags();
+      }
+
+      return exitCode;
+    }
   }
 
   private static int processRequest(
@@ -624,6 +651,18 @@ private static int runPersistentWorker() {
     return 0;
   }
 
+  private static void setDesugarJvmFlags() {
+    for (String flag : DESUGAR_JVM_FLAGS) {
+      System.setProperty(flag, "");
+    }
+  }
+
+  private static void unsetDesugarJvmFlags() {
+    for (String flag : DESUGAR_JVM_FLAGS) {
+      System.clearProperty(flag);
+    }
+  }
+
   public static void main(String[] args) throws Exception {
     if (args.length > 0 && args[0].equals("--persistent_worker")) {
       System.exit(runPersistentWorker());