Optimize Java string serialization. Patch from Evan Jones.

2 files changed, 41 insertions, 0 deletions

diff --git a/java/src/main/java/com/google/protobuf/CodedOutputStream.java b/java/src/main/java/com/google/protobuf/CodedOutputStream.java
index 58dd1506..18da6d9d 100644
--- a/java/src/main/java/com/google/protobuf/CodedOutputStream.java
+++ b/java/src/main/java/com/google/protobuf/CodedOutputStream.java
@@ -193,6 +193,23 @@ public final class CodedOutputStream {
     writeStringNoTag(value);
   }
 
+  /**
+   * Write a {@code string} field, including tag, to the stream, where bytes
+   * is the encoded version of value. Used by the SPEED version of messages
+   * to avoid performing the UTF-8 conversion twice. bytes is simply a hint
+   * and may be null. If it is null, value will be converted as usual.
+   */
+  public void writeStringCached(final int fieldNumber, final String value,
+                                ByteString bytes)
+                                throws IOException {
+    // The cache can be null if serializing without getting the size first, or
+    // if there are multiple threads.
+    if (bytes == null) {
+      bytes = ByteString.copyFromUtf8(value);
+    }
+    writeBytes(fieldNumber, bytes);
+  }
+
   /** Write a {@code group} field, including tag, to the stream. */
   public void writeGroup(final int fieldNumber, final MessageLite value)
                          throws IOException {
diff --git a/java/src/test/java/com/google/protobuf/CodedOutputStreamTest.java b/java/src/test/java/com/google/protobuf/CodedOutputStreamTest.java
index 48e54657..85691d60 100644
--- a/java/src/test/java/com/google/protobuf/CodedOutputStreamTest.java
+++ b/java/src/test/java/com/google/protobuf/CodedOutputStreamTest.java
@@ -36,6 +36,7 @@ import protobuf_unittest.UnittestProto.TestPackedTypes;
 import junit.framework.TestCase;
 
 import java.io.ByteArrayOutputStream;
+import java.io.IOException;
 import java.util.ArrayList;
 import java.util.List;
 
@@ -211,6 +212,29 @@ public class CodedOutputStreamTest extends TestCase {
       0x9abcdef012345678L);
   }
 
+  /** Test writing cached strings. */
+  public void testWriteStringCached() throws IOException {
+    final ByteArrayOutputStream output = new ByteArrayOutputStream();
+    final CodedOutputStream stream = CodedOutputStream.newInstance(output);
+
+    // Test writing a string that is not cached
+    stream.writeStringCached(5, "hello", null);
+    stream.flush();
+    CodedInputStream in = CodedInputStream.newInstance(output.toByteArray());
+    assertEquals(WireFormat.makeTag(5, WireFormat.WIRETYPE_LENGTH_DELIMITED),
+                 in.readTag());
+    assertEquals("hello", in.readString());
+
+    // Write a cached string: the real string is ignored
+    output.reset();
+    stream.writeStringCached(5, "ignored", ByteString.copyFromUtf8("hello"));
+    stream.flush();
+    in = CodedInputStream.newInstance(output.toByteArray());
+    assertEquals(WireFormat.makeTag(5, WireFormat.WIRETYPE_LENGTH_DELIMITED),
+                 in.readTag());
+    assertEquals("hello", in.readString());
+  }
+
   /** Test encodeZigZag32() and encodeZigZag64(). */
   public void testEncodeZigZag() throws Exception {
     assertEquals(0, CodedOutputStream.encodeZigZag32( 0));