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, 9 insertions, 12 deletions

diff --git a/src/tools/android/java/com/google/devtools/build/android/AndroidDataSerializer.java b/src/tools/android/java/com/google/devtools/build/android/AndroidDataSerializer.java
index 89120c3f24..1b1c0fbb19 100644
--- a/src/tools/android/java/com/google/devtools/build/android/AndroidDataSerializer.java
+++ b/src/tools/android/java/com/google/devtools/build/android/AndroidDataSerializer.java
@@ -14,12 +14,10 @@
 package com.google.devtools.build.android;
 
 import com.google.common.base.Stopwatch;
-import com.google.common.collect.Ordering;
 import com.google.devtools.build.android.ParsedAndroidData.KeyValueConsumer;
 import com.google.devtools.build.android.proto.SerializeFormat;
 import com.google.devtools.build.android.proto.SerializeFormat.Header;
 import com.google.protobuf.InvalidProtocolBufferException;
-
 import java.io.BufferedOutputStream;
 import java.io.ByteArrayOutputStream;
 import java.io.IOException;
@@ -33,7 +31,7 @@ import java.util.LinkedHashMap;
 import java.util.Map;
 import java.util.Map.Entry;
 import java.util.NavigableMap;
-import java.util.NavigableSet;
+import java.util.Set;
 import java.util.TreeMap;
 import java.util.concurrent.TimeUnit;
 import java.util.logging.Logger;
@@ -44,9 +42,7 @@ import java.util.logging.Logger;
 public class AndroidDataSerializer {
   private static final Logger logger = Logger.getLogger(AndroidDataSerializer.class.getName());
 
-  // TODO(corysmith): We might need a more performant comparison methodology than toString.
-  private final NavigableMap<DataKey, DataValue> entries =
-      new TreeMap<DataKey, DataValue>(Ordering.usingToString());
+  private final NavigableMap<DataKey, DataValue> entries = new TreeMap<>();
 
   public static AndroidDataSerializer create() {
     return new AndroidDataSerializer();
@@ -89,20 +85,21 @@ public class AndroidDataSerializer {
 
   private void writeKeyValuesTo(NavigableMap<DataKey, DataValue> map, OutputStream outStream)
       throws IOException {
-    NavigableSet<DataKey> keys = map.navigableKeySet();
-    int[] orderedValueSizes = new int[keys.size()];
+    Set<Entry<DataKey, DataValue>> entries = map.entrySet();
+    int[] orderedValueSizes = new int[entries.size()];
     int valueSizeIndex = 0;
     // Serialize all the values in sorted order to a intermediate buffer, so that the keys
     // can be associated with a value size.
     // TODO(corysmith): Tune the size of the byte array.
     ByteArrayOutputStream valuesOutputStream = new ByteArrayOutputStream(2048);
-    for (DataKey key : keys) {
-      orderedValueSizes[valueSizeIndex++] = map.get(key).serializeTo(key, valuesOutputStream);
+    for (Map.Entry<DataKey, DataValue> entry : entries) {
+      orderedValueSizes[valueSizeIndex++] = entry.getValue()
+          .serializeTo(entry.getKey(), valuesOutputStream);
     }
     // Serialize all the keys in sorted order
     valueSizeIndex = 0;
-    for (DataKey key : keys) {
-      key.serializeTo(outStream, orderedValueSizes[valueSizeIndex++]);
+    for (Map.Entry<DataKey, DataValue> entry : entries) {
+      entry.getKey().serializeTo(outStream, orderedValueSizes[valueSizeIndex++]);
     }
     // write the values to the output stream.
     outStream.write(valuesOutputStream.toByteArray());