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Unified Diff: third_party/protobuf/java/src/main/java/com/google/protobuf/LazyField.java

Issue 21208003: Update protobuf to r428, part 1. (Closed) Base URL: svn://svn.chromium.org/chrome/trunk/src/
Patch Set: Created 7 years, 4 months ago
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Index: third_party/protobuf/java/src/main/java/com/google/protobuf/LazyField.java
===================================================================
--- third_party/protobuf/java/src/main/java/com/google/protobuf/LazyField.java (revision 0)
+++ third_party/protobuf/java/src/main/java/com/google/protobuf/LazyField.java (revision 0)
@@ -0,0 +1,216 @@
+// Protocol Buffers - Google's data interchange format
+// Copyright 2008 Google Inc. All rights reserved.
+// http://code.google.com/p/protobuf/
+//
+// Redistribution and use in source and binary forms, with or without
+// modification, are permitted provided that the following conditions are
+// met:
+//
+// * Redistributions of source code must retain the above copyright
+// notice, this list of conditions and the following disclaimer.
+// * Redistributions in binary form must reproduce the above
+// copyright notice, this list of conditions and the following disclaimer
+// in the documentation and/or other materials provided with the
+// distribution.
+// * Neither the name of Google Inc. nor the names of its
+// contributors may be used to endorse or promote products derived from
+// this software without specific prior written permission.
+//
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+package com.google.protobuf;
+
+import java.io.IOException;
+import java.util.Iterator;
+import java.util.Map.Entry;
+
+/**
+ * LazyField encapsulates the logic of lazily parsing message fields. It stores
+ * the message in a ByteString initially and then parse it on-demand.
+ *
+ * LazyField is thread-compatible e.g. concurrent read are safe, however,
+ * synchronizations are needed under read/write situations.
+ *
+ * Now LazyField is only used to lazily load MessageSet.
+ * TODO(xiangl): Use LazyField to lazily load all messages.
+ *
+ * @author xiangl@google.com (Xiang Li)
+ */
+class LazyField {
+
+ final private MessageLite defaultInstance;
+ final private ExtensionRegistryLite extensionRegistry;
+
+ // Mutable because it is initialized lazily.
+ private ByteString bytes;
+ private volatile MessageLite value;
+ private volatile boolean isDirty = false;
+
+ public LazyField(MessageLite defaultInstance,
+ ExtensionRegistryLite extensionRegistry, ByteString bytes) {
+ this.defaultInstance = defaultInstance;
+ this.extensionRegistry = extensionRegistry;
+ this.bytes = bytes;
+ }
+
+ public MessageLite getValue() {
+ ensureInitialized();
+ return value;
+ }
+
+ /**
+ * LazyField is not thread-safe for write access. Synchronizations are needed
+ * under read/write situations.
+ */
+ public MessageLite setValue(MessageLite value) {
+ MessageLite originalValue = this.value;
+ this.value = value;
+ bytes = null;
+ isDirty = true;
+ return originalValue;
+ }
+
+ /**
+ * Due to the optional field can be duplicated at the end of serialized
+ * bytes, which will make the serialized size changed after LazyField
+ * parsed. Be careful when using this method.
+ */
+ public int getSerializedSize() {
+ if (isDirty) {
+ return value.getSerializedSize();
+ }
+ return bytes.size();
+ }
+
+ public ByteString toByteString() {
+ if (!isDirty) {
+ return bytes;
+ }
+ synchronized (this) {
+ if (!isDirty) {
+ return bytes;
+ }
+ bytes = value.toByteString();
+ isDirty = false;
+ return bytes;
+ }
+ }
+
+ @Override
+ public int hashCode() {
+ ensureInitialized();
+ return value.hashCode();
+ }
+
+ @Override
+ public boolean equals(Object obj) {
+ ensureInitialized();
+ return value.equals(obj);
+ }
+
+ @Override
+ public String toString() {
+ ensureInitialized();
+ return value.toString();
+ }
+
+ private void ensureInitialized() {
+ if (value != null) {
+ return;
+ }
+ synchronized (this) {
+ if (value != null) {
+ return;
+ }
+ try {
+ if (bytes != null) {
+ value = defaultInstance.getParserForType()
+ .parseFrom(bytes, extensionRegistry);
+ }
+ } catch (IOException e) {
+ // TODO(xiangl): Refactory the API to support the exception thrown from
+ // lazily load messages.
+ }
+ }
+ }
+
+ // ====================================================
+
+ /**
+ * LazyEntry and LazyIterator are used to encapsulate the LazyField, when
+ * users iterate all fields from FieldSet.
+ */
+ static class LazyEntry<K> implements Entry<K, Object> {
+ private Entry<K, LazyField> entry;
+
+ private LazyEntry(Entry<K, LazyField> entry) {
+ this.entry = entry;
+ }
+
+ @Override
+ public K getKey() {
+ return entry.getKey();
+ }
+
+ @Override
+ public Object getValue() {
+ LazyField field = entry.getValue();
+ if (field == null) {
+ return null;
+ }
+ return field.getValue();
+ }
+
+ public LazyField getField() {
+ return entry.getValue();
+ }
+
+ @Override
+ public Object setValue(Object value) {
+ if (!(value instanceof MessageLite)) {
+ throw new IllegalArgumentException(
+ "LazyField now only used for MessageSet, "
+ + "and the value of MessageSet must be an instance of MessageLite");
+ }
+ return entry.getValue().setValue((MessageLite) value);
+ }
+ }
+
+ static class LazyIterator<K> implements Iterator<Entry<K, Object>> {
+ private Iterator<Entry<K, Object>> iterator;
+
+ public LazyIterator(Iterator<Entry<K, Object>> iterator) {
+ this.iterator = iterator;
+ }
+
+ @Override
+ public boolean hasNext() {
+ return iterator.hasNext();
+ }
+
+ @SuppressWarnings("unchecked")
+ @Override
+ public Entry<K, Object> next() {
+ Entry<K, ?> entry = iterator.next();
+ if (entry.getValue() instanceof LazyField) {
+ return new LazyEntry<K>((Entry<K, LazyField>) entry);
+ }
+ return (Entry<K, Object>) entry;
+ }
+
+ @Override
+ public void remove() {
+ iterator.remove();
+ }
+ }
+}
Property changes on: third_party/protobuf/java/src/main/java/com/google/protobuf/LazyField.java
___________________________________________________________________
Added: svn:eol-style
+ LF

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