Improve resource DataKey serialization perf a bit

Address the TODO about using toString in the
TreeMap comparator by using DataKey#compareTo.
Also, use the entrySet to iterate K-V pairs
instead of calling get(key).

Synthetic benchmark w/ 10000 random keys:
Before: 260ms to serialize
After: 33ms to serialize

Less of a difference when there are few keys.

--
MOS_MIGRATED_REVID=128469407

1 files changed, 12 insertions, 1 deletions

diff --git a/src/tools/android/java/com/google/devtools/build/android/DataKey.java b/src/tools/android/java/com/google/devtools/build/android/DataKey.java
index e3a8b9d987..0fbbd1f9ed 100644
--- a/src/tools/android/java/com/google/devtools/build/android/DataKey.java
+++ b/src/tools/android/java/com/google/devtools/build/android/DataKey.java
@@ -26,7 +26,8 @@ import java.io.OutputStream;
  *
  * For Assets, it is the asset path from the assets directory.
  */
-public interface DataKey {
+public interface DataKey extends Comparable<DataKey> {
+
   /**
    * Writes the Key and the value size to a stream.
    *
@@ -40,4 +41,14 @@ public interface DataKey {
    * Returns a human readable string representation of the key.
    */
   String toPrettyString();
+
+  /**
+   * Defines a total ordering on the different key types to assist in compareTo operations.
+   */
+  enum KeyType {
+    ASSET_PATH,
+    FULL_QUALIFIED_NAME
+  }
+
+  KeyType getKeyType();
 }