From 9086d9643903c608ab015b0b7d903547a4e7b6f3 Mon Sep 17 00:00:00 2001
From: Feng Xiao <xfxyjwf@gmail.com>
Date: Wed, 13 Jul 2016 13:47:51 -0700
Subject: Integrate from internal code base.

---
 .../com/google/protobuf/CodedOutputStream.java     | 38 ++++++++++++++++++++++
 1 file changed, 38 insertions(+)

(limited to 'java/core/src/main/java/com/google/protobuf/CodedOutputStream.java')

diff --git a/java/core/src/main/java/com/google/protobuf/CodedOutputStream.java b/java/core/src/main/java/com/google/protobuf/CodedOutputStream.java
index 576a350f..4f5a9b77 100644
--- a/java/core/src/main/java/com/google/protobuf/CodedOutputStream.java
+++ b/java/core/src/main/java/com/google/protobuf/CodedOutputStream.java
@@ -144,6 +144,44 @@ public abstract class CodedOutputStream extends ByteOutput {
     return new NioEncoder(byteBuffer);
   }
 
+  /**
+   * Configures serialization to be deterministic.
+   *
+   * <p>The deterministic serialization guarantees that for a given binary, equal (defined by the
+   * {@code equals()} methods in protos) messages will always be serialized to the same bytes. This
+   * implies:
+   *
+   * <ul>
+   * <li>repeated serialization of a message will return the same bytes
+   * <li>different processes of the same binary (which may be executing on different machines) will
+   *     serialize equal messages to the same bytes.
+   * </ul>
+   *
+   * <p>Note the deterministic serialization is NOT canonical across languages; it is also unstable
+   * across different builds with schema changes due to unknown fields. Users who need canonical
+   * serialization, e.g. persistent storage in a canonical form, fingerprinting, etc, should define
+   * their own canonicalization specification and implement the serializer using reflection APIs
+   * rather than relying on this API.
+   *
+   * <p> Once set, the serializer will:  (Note this is an implementation detail and may subject to
+   * change in the future)
+   *
+   * <ul>
+   * <li> sort map entries by keys in lexicographical order or numerical order. Note: For string
+   *     keys, the order is based on comparing the Unicode value of each character in the strings.
+   *     The order may be different from the deterministic serialization in other languages where
+   *     maps are sorted on the lexicographical order of the UTF8 encoded keys.
+   * </ul>
+   */
+  public final void useDeterministicSerialization() {
+    serializationDeterministic = true;
+  }
+
+  boolean isSerializationDeterministic() {
+    return serializationDeterministic;
+  }
+  private boolean serializationDeterministic;
+
   /**
    * Create a new {@code CodedOutputStream} that writes to the given {@link ByteBuffer}.
    *
-- 
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