| // Copyright 2018 The Bazel Authors. All rights reserved. |
| // |
| // Licensed under the Apache License, Version 2.0 (the "License"); |
| // you may not use this file except in compliance with the License. |
| // You may obtain a copy of the License at |
| // |
| // http://www.apache.org/licenses/LICENSE-2.0 |
| // |
| // Unless required by applicable law or agreed to in writing, software |
| // distributed under the License is distributed on an "AS IS" BASIS, |
| // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| // See the License for the specific language governing permissions and |
| // limitations under the License. |
| |
| package com.google.devtools.build.lib.skyframe.serialization; |
| |
| import com.google.common.annotations.VisibleForTesting; |
| import com.google.devtools.build.lib.unsafe.StringUnsafe; |
| import com.google.protobuf.CodedInputStream; |
| import com.google.protobuf.CodedOutputStream; |
| import java.io.IOException; |
| import java.util.Arrays; |
| |
| /** |
| * A high-performance {@link ObjectCodec} for {@link String} objects specialized for Strings in |
| * JDK9, where a String can be represented as a byte array together with a single byte (0 or 1) for |
| * Latin-1 or UTF16 encoding. |
| */ |
| public class UnsafeJdk9StringCodec implements ObjectCodec<String> { |
| @VisibleForTesting |
| public static boolean canUseUnsafeCodec() { |
| return StringUnsafe.canUse(); |
| } |
| |
| private final StringUnsafe stringUnsafe; |
| |
| public UnsafeJdk9StringCodec() { |
| stringUnsafe = StringUnsafe.getInstance(); |
| } |
| |
| @Override |
| public Class<? extends String> getEncodedClass() { |
| return String.class; |
| } |
| |
| @Override |
| public MemoizationStrategy getStrategy() { |
| // Don't memoize strings inside memoizing serialization, to preserve current behavior. |
| // TODO(janakr,brandjon,michajlo): Is it actually a problem to memoize strings? Doubt there |
| // would be much performance impact from increasing the size of the identity map, and we |
| // could potentially drop our string tables in the future. |
| return MemoizationStrategy.DO_NOT_MEMOIZE; |
| } |
| |
| @Override |
| public void serialize(SerializationContext context, String obj, CodedOutputStream codedOut) |
| throws SerializationException, IOException { |
| byte coder = stringUnsafe.getCoder(obj); |
| byte[] value = stringUnsafe.getByteArray(obj); |
| // Optimize for the case that coder == 0, in which case we can just write the length here, |
| // potentially using just one byte. If coder != 0, we'll use 4 bytes, but that's vanishingly |
| // rare. |
| if (coder == 0) { |
| codedOut.writeInt32NoTag(value.length); |
| } else if (coder == 1) { |
| codedOut.writeInt32NoTag(-value.length); |
| } else { |
| throw new SerializationException("Unexpected coder value: " + coder + " for " + obj); |
| } |
| codedOut.writeRawBytes(value); |
| } |
| |
| @Override |
| public String deserialize(DeserializationContext context, CodedInputStream codedIn) |
| throws SerializationException, IOException { |
| int length = codedIn.readInt32(); |
| byte coder; |
| if (length >= 0) { |
| coder = 0; |
| } else { |
| coder = 1; |
| length = -length; |
| } |
| byte[] value = codedIn.readRawBytes(length); |
| try { |
| return stringUnsafe.newInstance(value, coder); |
| } catch (ReflectiveOperationException e) { |
| throw new SerializationException( |
| "Could not instantiate string: " + Arrays.toString(value) + ", " + coder, e); |
| } |
| } |
| } |