Make the AndroidResourceProcessor more deterministic by setting the R.txt ids to 0x1, the java ids to a hash of pkg, resource type, and resource name (robolectric needs unique ids) and ensuring the last modified date is set to the epoch. This only affects library aapt invocations.

--
MOS_MIGRATED_REVID=111076315

2 files changed, 78 insertions, 10 deletions

diff --git a/src/tools/android/java/com/google/devtools/build/android/AndroidResourceProcessingAction.java b/src/tools/android/java/com/google/devtools/build/android/AndroidResourceProcessingAction.java
index c621ba7095..6161578504 100644
--- a/src/tools/android/java/com/google/devtools/build/android/AndroidResourceProcessingAction.java
+++ b/src/tools/android/java/com/google/devtools/build/android/AndroidResourceProcessingAction.java
@@ -45,7 +45,6 @@ import java.nio.file.FileSystems;
 import java.nio.file.Files;
 import java.nio.file.Path;
 import java.util.Collection;
-import java.util.LinkedHashSet;
 import java.util.List;
 import java.util.concurrent.TimeUnit;
 import java.util.logging.Logger;
@@ -356,13 +355,16 @@ public class AndroidResourceProcessingAction {
           options.proguardOutput);
       LOGGER.fine(String.format("appt finished at %sms", timer.elapsed(TimeUnit.MILLISECONDS)));
       if (options.srcJarOutput != null) {
-        resourceProcessor.createSrcJar(generatedSources, options.srcJarOutput);
+        resourceProcessor.createSrcJar(generatedSources, options.srcJarOutput,
+            VariantConfiguration.Type.LIBRARY == options.packageType);
       }
       if (options.rOutput != null) {
-        resourceProcessor.copyRToOutput(generatedSources, options.rOutput);
+        resourceProcessor.copyRToOutput(generatedSources, options.rOutput,
+            VariantConfiguration.Type.LIBRARY == options.packageType);
       }
       if (options.symbolsTxtOut != null) {
-        resourceProcessor.copyRToOutput(generatedSources, options.symbolsTxtOut);
+        resourceProcessor.copyRToOutput(generatedSources, options.symbolsTxtOut,
+            VariantConfiguration.Type.LIBRARY == options.packageType);
       }
       LOGGER.fine(String.format("Packaging finished at %sms",
           timer.elapsed(TimeUnit.MILLISECONDS)));
diff --git a/src/tools/android/java/com/google/devtools/build/android/AndroidResourceProcessor.java b/src/tools/android/java/com/google/devtools/build/android/AndroidResourceProcessor.java
index d5f1e1a3e8..4951ad9977 100644
--- a/src/tools/android/java/com/google/devtools/build/android/AndroidResourceProcessor.java
+++ b/src/tools/android/java/com/google/devtools/build/android/AndroidResourceProcessor.java
@@ -13,6 +13,9 @@
 // limitations under the License.
 package com.google.devtools.build.android;
 
+import static java.nio.charset.StandardCharsets.UTF_8;
+
+import com.google.common.base.Joiner;
 import com.google.common.base.Throwables;
 import com.google.common.collect.ImmutableList;
 import com.google.common.collect.ImmutableMap;
@@ -37,14 +40,20 @@ import com.android.utils.StdLogger;
 
 import java.io.File;
 import java.io.IOException;
+import java.nio.ByteBuffer;
+import java.nio.charset.StandardCharsets;
 import java.nio.file.FileVisitResult;
 import java.nio.file.Files;
 import java.nio.file.Path;
 import java.nio.file.SimpleFileVisitor;
 import java.nio.file.attribute.BasicFileAttributes;
+import java.nio.file.attribute.FileTime;
 import java.util.ArrayList;
 import java.util.Collection;
 import java.util.List;
+import java.util.Objects;
+import java.util.regex.Matcher;
+import java.util.regex.Pattern;
 import java.util.zip.CRC32;
 import java.util.zip.ZipEntry;
 import java.util.zip.ZipOutputStream;
@@ -53,6 +62,7 @@ import java.util.zip.ZipOutputStream;
  * Provides a wrapper around the AOSP build tools for resource processing.
  */
 public class AndroidResourceProcessor {
+  private static final Pattern HEX_REGEX = Pattern.compile("0x[0-9A-Fa-f]{8}");
   private final StdLogger stdLogger;
 
   public AndroidResourceProcessor(StdLogger stdLogger) {
@@ -61,18 +71,29 @@ public class AndroidResourceProcessor {
 
   /**
    * Copies the R.txt to the expected place.
+   * @param generatedSourceRoot The path to the generated R.txt.
+   * @param rOutput The Path to write the R.txt.
+   * @param staticIds Boolean that indicates if the ids should be set to 0x1 for caching purposes.
    */
-  public void copyRToOutput(Path generatedSourceRoot, Path rOutput) {
+  public void copyRToOutput(Path generatedSourceRoot, Path rOutput, boolean staticIds) {
     try {
       Files.createDirectories(rOutput.getParent());
       final Path source = generatedSourceRoot.resolve("R.txt");
       if (Files.exists(source)) {
-        Files.copy(source, rOutput);
+        if (staticIds) {
+          String contents = HEX_REGEX.matcher(Joiner.on("\n").join(
+              Files.readAllLines(source, StandardCharsets.UTF_8))).replaceAll("0x1");
+          Files.write(rOutput, contents.getBytes(StandardCharsets.UTF_8));
+        } else {
+          Files.copy(source, rOutput);
+        }
       } else {
         // The R.txt wasn't generated, create one for future inheritance, as Bazel always requires
         // outputs. This state occurs when there are no resource directories.
         Files.createFile(rOutput);
       }
+      // Set to the epoch for caching purposes.
+      Files.setLastModifiedTime(rOutput, FileTime.fromMillis(0L));
     } catch (IOException e) {
       Throwables.propagate(e);
     }
@@ -80,14 +101,16 @@ public class AndroidResourceProcessor {
 
   /**
    * Creates a zip archive from all found R.java files.
+   * @param staticIds TODO(corysmith):
    */
-  public void createSrcJar(Path generatedSourcesRoot, Path srcJar) {
+  public void createSrcJar(Path generatedSourcesRoot, Path srcJar, boolean staticIds) {
     try {
       Files.createDirectories(srcJar.getParent());
       try (final ZipOutputStream zip = new ZipOutputStream(Files.newOutputStream(srcJar))) {
         Files.walkFileTree(generatedSourcesRoot,
-            new SymbolFileSrcJarBuildingVisitor(zip, generatedSourcesRoot));
+            new SymbolFileSrcJarBuildingVisitor(zip, generatedSourcesRoot, staticIds));
       }
+      Files.setLastModifiedTime(srcJar, FileTime.fromMillis(0L));
     } catch (IOException e) {
       Throwables.propagate(e);
     }
@@ -141,6 +164,12 @@ public class AndroidResourceProcessor {
         resourceConfigs,
         true // boolean enforceUniquePackageName
         );
+    if (proguardOut != null) {
+      Files.setLastModifiedTime(proguardOut, FileTime.fromMillis(0L));
+    }
+    if (packageOut != null) {
+      Files.setLastModifiedTime(packageOut, FileTime.fromMillis(0L));
+    }
   }
 
   private File processManifest(
@@ -257,22 +286,59 @@ public class AndroidResourceProcessor {
   /**
    * A FileVisitor that will add all R.java files to be stored in a zip archive.
    */
-  private final class SymbolFileSrcJarBuildingVisitor extends SimpleFileVisitor<Path> {
+  private static final class SymbolFileSrcJarBuildingVisitor extends SimpleFileVisitor<Path> {
+    static final Pattern PACKAGE_PATTERN = Pattern.compile(
+        "\\s*package ([a-zA-Z_$][a-zA-Z\\d_$]*(?:\\.[a-zA-Z_$][a-zA-Z\\d_$]*)*)");
+    static final Pattern ID_PATTERN = Pattern.compile(
+        "public static int ([\\w\\.]+)=0x[0-9A-fa-f]+;");
+    static final Pattern INNER_CLASS = Pattern.compile("public static class ([a-z_]*) \\{(.*?)\\}",
+        Pattern.DOTALL);
 
     // The earliest date representable in a zip file, 1-1-1980.
     private static final long ZIP_EPOCH = 315561600000L;
     private final ZipOutputStream zip;
     private final Path root;
+    private final boolean staticIds;
 
-    private SymbolFileSrcJarBuildingVisitor(ZipOutputStream zip, Path root) {
+    private SymbolFileSrcJarBuildingVisitor(ZipOutputStream zip, Path root, boolean staticIds) {
       this.zip = zip;
       this.root = root;
+      this.staticIds = staticIds;
+    }
+
+    private String replaceIdsWithStaticIds(String contents) {
+      Matcher packageMatcher = PACKAGE_PATTERN.matcher(contents);
+      if (!packageMatcher.find()) {
+        return contents;
+      }
+      String pkg = packageMatcher.group(1);
+      StringBuilder out = new StringBuilder();
+      Matcher innerClassMatcher = INNER_CLASS.matcher(contents);
+      while (innerClassMatcher.find()) {
+        String resourceType = innerClassMatcher.group(1);
+        Matcher idMatcher = ID_PATTERN.matcher(innerClassMatcher.group(2));
+        StringBuilder resourceIds = new StringBuilder();
+        while (idMatcher.find()) {
+          String javaId = idMatcher.group(1);
+          idMatcher.appendReplacement(resourceIds, String.format("public static int %s=0x%08X;",
+              javaId, Objects.hash(pkg, resourceType, javaId)));
+        }
+        idMatcher.appendTail(resourceIds);
+        innerClassMatcher.appendReplacement(out,
+            String.format("public static class %s {%s}", resourceType, resourceIds.toString()));
+      }
+      innerClassMatcher.appendTail(out);
+      return out.toString();
     }
 
     @Override
     public FileVisitResult visitFile(Path file, BasicFileAttributes attrs) throws IOException {
       if (file.getFileName().endsWith("R.java")) {
         byte[] content = Files.readAllBytes(file);
+        if (staticIds) {
+          content = replaceIdsWithStaticIds(UTF_8.decode(
+              ByteBuffer.wrap(content)).toString()).getBytes(UTF_8);
+        }
         ZipEntry entry = new ZipEntry(root.relativize(file).toString());
 
         entry.setMethod(ZipEntry.STORED);