| // 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; |
| } |
| |
| public K getKey() { |
| return entry.getKey(); |
| } |
| |
| public Object getValue() { |
| LazyField field = entry.getValue(); |
| if (field == null) { |
| return null; |
| } |
| return field.getValue(); |
| } |
| |
| public LazyField getField() { |
| return entry.getValue(); |
| } |
| |
| 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; |
| } |
| |
| public boolean hasNext() { |
| return iterator.hasNext(); |
| } |
| |
| @SuppressWarnings("unchecked") |
| 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; |
| } |
| |
| public void remove() { |
| iterator.remove(); |
| } |
| } |
| } |