8185e47822
This patch adds a hashtable-based LRU cache. This should be significantly higher performance than the GenerationCache it is intended to replace. It is a large part of the fix for bug 7271109 TextLayoutCache low-level performance issues. We added a new method to BasicHashtable to detect when rehashing is needed, because the internal linked list pointers would get invalidated by that rehashing. Also, the hash_type specialized to pointers had a small flaw. Change-Id: I950c2083f96519777b851dbe157100e0a334caec
45 lines
1.4 KiB
C++
45 lines
1.4 KiB
C++
/*
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* Copyright (C) 2012 The Android Open Source Project
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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/* Implementation of Jenkins one-at-a-time hash function. These choices are
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* optimized for code size and portability, rather than raw speed. But speed
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* should still be quite good.
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**/
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#include <utils/TypeHelpers.h>
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namespace android {
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/* The Jenkins hash of a sequence of 32 bit words A, B, C is:
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* Whiten(Mix(Mix(Mix(0, A), B), C)) */
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inline uint32_t JenkinsHashMix(uint32_t hash, uint32_t data) {
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hash += data;
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hash += (hash << 10);
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hash ^= (hash >> 6);
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return hash;
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}
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hash_t JenkinsHashWhiten(uint32_t hash);
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/* Helpful utility functions for hashing data in 32 bit chunks */
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uint32_t JenkinsHashMixBytes(uint32_t hash, const uint8_t* bytes, size_t size);
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uint32_t JenkinsHashMixShorts(uint32_t hash, const uint16_t* shorts, size_t size);
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}
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