60 lines
1.6 KiB
C++
60 lines
1.6 KiB
C++
/*
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Copyright (c) 2013 Microsoft Corporation. All rights reserved.
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Released under Apache 2.0 license as described in the file LICENSE.
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Author: Leonardo de Moura
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*/
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#pragma once
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#include <mutex>
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namespace lean {
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/**
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\brief Auxiliary class that wraps a pointer to a type that has a
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set_interrupt method. The set_interrupt can be invoked from a different
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execution thread. To prevent race conditions, we use mutex whenever we
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reset the pointer, or invoke the set_interrupt method.
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The common usage scenario is:
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1) Thread A creates creates a new object Obj and invokes set(Obj)
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2) Thread B invokes set_interrupt, which invokes Obj->set_interrupt
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3) Thread A invokes set(nullptr) before deleting Obj.
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We use the mutex to avoid a race condition in 2&3.
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*/
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template<typename T>
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class interruptable_ptr {
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T * m_ptr;
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std::mutex m_mutex;
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public:
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interruptable_ptr():m_ptr(nullptr) {}
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T * set(T * ptr) {
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std::lock_guard<std::mutex> lock(m_mutex);
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T * old = m_ptr;
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m_ptr = ptr;
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return old;
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}
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void set_interrupt(bool flag) {
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std::lock_guard<std::mutex> lock(m_mutex);
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if (m_ptr)
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m_ptr->set_interrupt(flag);
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}
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};
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/**
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\brief Auxiliary class for setting/resetting a interruptable_ptr.
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*/
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template<typename T>
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struct scoped_set_interruptable_ptr {
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interruptable_ptr<T> & m_ptr;
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T * m_old_p;
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public:
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scoped_set_interruptable_ptr(interruptable_ptr<T> & ptr, T * p):m_ptr(ptr) {
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m_old_p = m_ptr.set(p);
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}
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~scoped_set_interruptable_ptr() {
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m_ptr.set(m_old_p);
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}
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};
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}
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