Add action to write android_binary and lib R.classes directly

For android_binary rules, we regenerate all of
the R.java of the libraries to get the final
resource IDs. Compiling all of them together can
be slow with the normal JavaBuilder, so add a
specialized class writer.

Example build with many R.java classes:
- R.java -> R.class via JavaBuilder: over 80s
- ErrorProne takes about 40% of that. So turning off
  ErrorProne would be projected to be 48s.
  Some of ErrorProne slowness is from static field
  checks (e.g., on Flag classes), which may look
  up the same Type over and over.

In comparison, if we write our own bytecode with ASM:
- ~16s total
- 4.7s to parse R.txt
- 4.8s to write class files
- 5.8s to copy and compress .jar

TODO: clean up SymbolLoader patching (upstream)

This only creates the action. We will need to
separately wire this up in blaze.

NOTE: This also makes the exising R.txt loading
used by live code multi-threaded, since that is
partly I/O-bound. Something to watch out for
(for flakiness, etc.) once this is submitted.

--
MOS_MIGRATED_REVID=125384467

1 files changed, 4 insertions, 5 deletions

diff --git a/src/tools/android/java/com/google/devtools/build/android/ResourceShrinkerAction.java b/src/tools/android/java/com/google/devtools/build/android/ResourceShrinkerAction.java
index 69317a135b..7846844273 100644
--- a/src/tools/android/java/com/google/devtools/build/android/ResourceShrinkerAction.java
+++ b/src/tools/android/java/com/google/devtools/build/android/ResourceShrinkerAction.java
@@ -160,11 +160,10 @@ public class ResourceShrinkerAction {
     options = optionsParser.getOptions(Options.class);
 
     AndroidResourceProcessor resourceProcessor = new AndroidResourceProcessor(stdLogger);
-    try {
-      // Setup temporary working directories.
-      Path working = Files.createTempDirectory("resource_shrinker_tmp");
-      working.toFile().deleteOnExit();
-
+    // Setup temporary working directories.
+    try (ScopedTemporaryDirectory scopedTmp =
+        new ScopedTemporaryDirectory("resource_shrinker_tmp")) {
+      Path working = scopedTmp.getPath();
       final Path resourceFiles = working.resolve("resource_files");
 
       final Path shrunkResources = working.resolve("shrunk_resources");