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389f13012f
Based on the STL class of the same name, it guards a mutex while also allowing it to be unlocked conditionally before destruction. This eliminates the last naked usages of mutexes in LLVM and clang. It also uncovered and fixed a bug in callExternalFunction() when compiled without USE_LIBFFI, where the mutex would never be unlocked if the end of the function was reached. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@216338 91177308-0d34-0410-b5e6-96231b3b80d8
68 lines
2.0 KiB
C++
68 lines
2.0 KiB
C++
//===-- Support/UniqueLock.h - Acquire/Release Mutex In Scope ---*- C++ -*-===//
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//
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// The LLVM Compiler Infrastructure
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//
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// This file is distributed under the University of Illinois Open Source
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// License. See LICENSE.TXT for details.
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//
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//===----------------------------------------------------------------------===//
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//
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// This file defines a guard for a block of code that ensures a Mutex is locked
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// upon construction and released upon destruction.
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//
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//===----------------------------------------------------------------------===//
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#ifndef LLVM_SUPPORT_UNIQUE_LOCK_H
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#define LLVM_SUPPORT_UNIQUE_LOCK_H
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#include "llvm/Support/Mutex.h"
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namespace llvm {
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/// A pared-down imitation of std::unique_lock from C++11. Contrary to the
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/// name, it's really more of a wrapper for a lock. It may or may not have
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/// an associated mutex, which is guaranteed to be locked upon creation
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/// and unlocked after destruction. unique_lock can also unlock the mutex
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/// and re-lock it freely during its lifetime.
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/// @brief Guard a section of code with a mutex.
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template<typename MutexT>
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class unique_lock {
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MutexT *M;
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bool locked;
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unique_lock(const unique_lock &) LLVM_DELETED_FUNCTION;
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void operator=(const unique_lock &) LLVM_DELETED_FUNCTION;
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public:
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unique_lock() : M(nullptr), locked(false) {}
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explicit unique_lock(MutexT &m) : M(&m), locked(true) { M->lock(); }
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void operator=(unique_lock &&o) {
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if (owns_lock())
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M->unlock();
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M = o.M;
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locked = o.locked;
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o.M = nullptr;
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o.locked = false;
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}
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~unique_lock() { if (owns_lock()) M->unlock(); }
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void lock() {
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assert(!locked && "mutex already locked!");
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assert(M && "no associated mutex!");
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M->lock();
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locked = true;
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}
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void unlock() {
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assert(locked && "unlocking a mutex that isn't locked!");
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assert(M && "no associated mutex!");
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M->unlock();
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locked = false;
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}
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bool owns_lock() { return locked; }
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};
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}
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#endif // LLVM_SUPPORT_UNIQUE_LOCK_H
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