a1b5b42d55
(This is a merge of http://go/wvgerrit/70666) We need a reader-writer lock implementation in order to make use of the new threading guarantees in OEMCrypto v15. However, we do not have access to an STL reader-writer lock due to only being on C++11. This patch adds a home-grown reader-writer lock, as well as tests to verify that its behavior is sound. Bug: 70889998 Bug: 118584039 Test: CE CDM Unit Tests Test: Android Unit Tests Change-Id: Iaddcefb50e72452fbd27d04879eacf775484e675
61 lines
1.2 KiB
C++
61 lines
1.2 KiB
C++
// Copyright 2019 Google LLC. All Rights Reserved. This file and proprietary
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// source code may only be used and distributed under the Widevine Master
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// License Agreement.
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#include "rw_lock.h"
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#include "log.h"
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namespace wvcdm {
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shared_mutex::~shared_mutex() {
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if (reader_count_ > 0) {
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LOGE("shared_mutex destroyed with active readers!");
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}
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if (has_writer_) {
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LOGE("shared_mutex destroyed with an active writer!");
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}
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}
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void shared_mutex::lock_shared() {
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std::unique_lock<std::mutex> lock(mutex_);
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while (has_writer_) {
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condition_variable_.wait(lock);
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}
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++reader_count_;
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}
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void shared_mutex::unlock_shared() {
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std::unique_lock<std::mutex> lock(mutex_);
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--reader_count_;
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if (reader_count_ == 0) {
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condition_variable_.notify_all();
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}
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}
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bool shared_mutex::lock_implementation(bool abort_if_unavailable) {
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std::unique_lock<std::mutex> lock(mutex_);
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while (reader_count_ > 0 || has_writer_) {
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if (abort_if_unavailable) return false;
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condition_variable_.wait(lock);
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}
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has_writer_ = true;
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return true;
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}
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void shared_mutex::unlock() {
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std::unique_lock<std::mutex> lock(mutex_);
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has_writer_ = false;
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condition_variable_.notify_all();
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}
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} // namespace wvcdm
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