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authorDave Hawkey <dhawkey@google.com>2014-03-20 10:55:41 -0600
committerDave Hawkey <dhawkey@google.com>2014-03-21 09:27:23 -0600
commitc6e12c6702ca764486f952654ba1568f00efe813 (patch)
treeb1dcfb28a8cef29d898e45637852816eb490ddc2 /java
parent51ef8f39de376fe71ce5d2c682abe4f974cf8074 (diff)
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Don't reset cachedSize to 0 in getSerializedSize
This avoids a race-condition when cachedSize is momentarily set to 0 for non-empty messages if multiple threads call getSerializedSize (e.g. during serialization). Change-Id: I15a8ded92edbf41bf1c8d787960c5bbbc8a323c5
Diffstat (limited to 'java')
-rw-r--r--java/README.txt9
-rw-r--r--java/src/main/java/com/google/protobuf/nano/ExtendableMessageNano.java3
-rw-r--r--java/src/main/java/com/google/protobuf/nano/MessageNano.java19
-rw-r--r--java/src/test/java/com/google/protobuf/NanoTest.java15
4 files changed, 39 insertions, 7 deletions
diff --git a/java/README.txt b/java/README.txt
index 13865f6..f958d14 100644
--- a/java/README.txt
+++ b/java/README.txt
@@ -437,6 +437,15 @@ and the runtime overhead. An overview of Nano features:
MessageNano.
- The 'bytes' type translates to the Java type byte[].
+The generated messages are not thread-safe for writes, but may be
+used simultaneously from multiple threads in a read-only manner.
+In other words, an appropriate synchronization mechanism (such as
+a ReadWriteLock) must be used to ensure that a message, its
+ancestors, and descendants are not accessed by any other threads
+while the message is being modified. Field reads, getter methods,
+toByteArray(...), writeTo(...), getCachedSize(), and
+getSerializedSize() are all considered read-only operations.
+
IMPORTANT: If you have fields with defaults and opt out of accessors
How fields with defaults are serialized has changed. Because we don't
diff --git a/java/src/main/java/com/google/protobuf/nano/ExtendableMessageNano.java b/java/src/main/java/com/google/protobuf/nano/ExtendableMessageNano.java
index 839f21c..63c8afc 100644
--- a/java/src/main/java/com/google/protobuf/nano/ExtendableMessageNano.java
+++ b/java/src/main/java/com/google/protobuf/nano/ExtendableMessageNano.java
@@ -47,7 +47,7 @@ public abstract class ExtendableMessageNano<M extends ExtendableMessageNano<M>>
protected List<UnknownFieldData> unknownFieldData;
@Override
- public int getSerializedSize() {
+ protected int computeSerializedSize() {
int size = 0;
int unknownFieldCount = unknownFieldData == null ? 0 : unknownFieldData.size();
for (int i = 0; i < unknownFieldCount; i++) {
@@ -55,7 +55,6 @@ public abstract class ExtendableMessageNano<M extends ExtendableMessageNano<M>>
size += CodedOutputByteBufferNano.computeRawVarint32Size(unknownField.tag);
size += unknownField.bytes.length;
}
- cachedSize = size;
return size;
}
diff --git a/java/src/main/java/com/google/protobuf/nano/MessageNano.java b/java/src/main/java/com/google/protobuf/nano/MessageNano.java
index 82dc6cc..3119c93 100644
--- a/java/src/main/java/com/google/protobuf/nano/MessageNano.java
+++ b/java/src/main/java/com/google/protobuf/nano/MessageNano.java
@@ -38,7 +38,7 @@ import java.io.IOException;
* @author wink@google.com Wink Saville
*/
public abstract class MessageNano {
- protected int cachedSize = -1;
+ protected volatile int cachedSize = -1;
/**
* Get the number of bytes required to encode this message.
@@ -60,10 +60,19 @@ public abstract class MessageNano {
* The size is cached and the cached result can be retrieved
* using getCachedSize().
*/
- public int getSerializedSize() {
- // This is overridden if the generated message has serialized fields.
- cachedSize = 0;
- return 0;
+ public final int getSerializedSize() {
+ int size = computeSerializedSize();
+ cachedSize = size;
+ return size;
+ }
+
+ /**
+ * Computes the number of bytes required to encode this message. This does not update the
+ * cached size.
+ */
+ protected int computeSerializedSize() {
+ // This is overridden if the generated message has serialized fields.
+ return 0;
}
/**
diff --git a/java/src/test/java/com/google/protobuf/NanoTest.java b/java/src/test/java/com/google/protobuf/NanoTest.java
index 9987cac..4aa6d89 100644
--- a/java/src/test/java/com/google/protobuf/NanoTest.java
+++ b/java/src/test/java/com/google/protobuf/NanoTest.java
@@ -105,6 +105,14 @@ public class NanoTest extends TestCase {
assertEquals(456, newMsg.d);
assertEquals(2, msg.nestedMsg.bb);
assertEquals(SimpleMessageNano.BAR, msg.defaultNestedEnum);
+
+ msg.nestedMsg = null;
+ assertEquals(msgSerializedSize, msg.getCachedSize());
+ assertTrue(msgSerializedSize != msg.getSerializedSize());
+
+ msg.clear();
+ assertEquals(0, msg.getCachedSize());
+ assertEquals(0, msg.getSerializedSize());
}
public void testRecursiveMessageNano() throws Exception {
@@ -3532,6 +3540,13 @@ public class NanoTest extends TestCase {
assertTrue(Arrays.equals(new boolean[] {false, true, false, true}, nonPacked.bools));
}
+ public void testMessageNoFields() {
+ SingleMessageNano msg = new SingleMessageNano();
+ assertEquals(0, msg.getSerializedSize());
+ assertEquals(0, msg.getCachedSize());
+ assertEquals(0, MessageNano.toByteArray(msg).length);
+ }
+
private void assertRepeatedPackablesEqual(
NanoRepeatedPackables.NonPacked nonPacked, NanoRepeatedPackables.Packed packed) {
// Not using MessageNano.equals() -- that belongs to a separate test.