Merge pull request #9684 from liamwhite/read-the-spec
polyfill_thread: satisfy execution ordering requirements of stop_callback
This commit is contained in:
commit
d960723dc9
1 changed files with 48 additions and 39 deletions
|
@ -41,17 +41,18 @@ bool StoppableTimedWait(std::stop_token token, const std::chrono::duration<Rep,
|
|||
#include <chrono>
|
||||
#include <condition_variable>
|
||||
#include <functional>
|
||||
#include <list>
|
||||
#include <map>
|
||||
#include <memory>
|
||||
#include <mutex>
|
||||
#include <optional>
|
||||
#include <thread>
|
||||
#include <type_traits>
|
||||
#include <utility>
|
||||
|
||||
namespace std {
|
||||
namespace polyfill {
|
||||
|
||||
using stop_state_callbacks = list<function<void()>>;
|
||||
using stop_state_callback = size_t;
|
||||
|
||||
class stop_state {
|
||||
public:
|
||||
|
@ -59,61 +60,69 @@ public:
|
|||
~stop_state() = default;
|
||||
|
||||
bool request_stop() {
|
||||
stop_state_callbacks callbacks;
|
||||
unique_lock lk{m_lock};
|
||||
|
||||
{
|
||||
scoped_lock lk{m_lock};
|
||||
|
||||
if (m_stop_requested.load()) {
|
||||
// Already set, nothing to do
|
||||
if (m_stop_requested) {
|
||||
// Already set, nothing to do.
|
||||
return false;
|
||||
}
|
||||
|
||||
// Set as requested
|
||||
// Mark stop requested.
|
||||
m_stop_requested = true;
|
||||
|
||||
// Copy callback list
|
||||
callbacks = m_callbacks;
|
||||
}
|
||||
while (!m_callbacks.empty()) {
|
||||
// Get an iterator to the first element.
|
||||
const auto it = m_callbacks.begin();
|
||||
|
||||
for (auto callback : callbacks) {
|
||||
callback();
|
||||
// Move the callback function out of the map.
|
||||
function<void()> f;
|
||||
swap(it->second, f);
|
||||
|
||||
// Erase the now-empty map element.
|
||||
m_callbacks.erase(it);
|
||||
|
||||
// Run the callback.
|
||||
if (f) {
|
||||
f();
|
||||
}
|
||||
}
|
||||
|
||||
return true;
|
||||
}
|
||||
|
||||
bool stop_requested() const {
|
||||
return m_stop_requested.load();
|
||||
unique_lock lk{m_lock};
|
||||
return m_stop_requested;
|
||||
}
|
||||
|
||||
stop_state_callbacks::const_iterator insert_callback(function<void()> f) {
|
||||
stop_state_callbacks::const_iterator ret{};
|
||||
bool should_run{};
|
||||
stop_state_callback insert_callback(function<void()> f) {
|
||||
unique_lock lk{m_lock};
|
||||
|
||||
{
|
||||
scoped_lock lk{m_lock};
|
||||
should_run = m_stop_requested.load();
|
||||
m_callbacks.push_front(f);
|
||||
ret = m_callbacks.begin();
|
||||
}
|
||||
|
||||
if (should_run) {
|
||||
if (m_stop_requested) {
|
||||
// Stop already requested. Don't insert anything,
|
||||
// just run the callback synchronously.
|
||||
if (f) {
|
||||
f();
|
||||
}
|
||||
return 0;
|
||||
}
|
||||
|
||||
// Insert the callback.
|
||||
stop_state_callback ret = ++m_next_callback;
|
||||
m_callbacks.emplace(ret, move(f));
|
||||
return ret;
|
||||
}
|
||||
|
||||
void remove_callback(stop_state_callbacks::const_iterator it) {
|
||||
scoped_lock lk{m_lock};
|
||||
m_callbacks.erase(it);
|
||||
void remove_callback(stop_state_callback cb) {
|
||||
unique_lock lk{m_lock};
|
||||
m_callbacks.erase(cb);
|
||||
}
|
||||
|
||||
private:
|
||||
mutex m_lock;
|
||||
atomic<bool> m_stop_requested;
|
||||
stop_state_callbacks m_callbacks;
|
||||
mutable recursive_mutex m_lock;
|
||||
map<stop_state_callback, function<void()>> m_callbacks;
|
||||
stop_state_callback m_next_callback{0};
|
||||
bool m_stop_requested{false};
|
||||
};
|
||||
|
||||
} // namespace polyfill
|
||||
|
@ -223,7 +232,7 @@ public:
|
|||
}
|
||||
~stop_callback() {
|
||||
if (m_stop_state && m_callback) {
|
||||
m_stop_state->remove_callback(*m_callback);
|
||||
m_stop_state->remove_callback(m_callback);
|
||||
}
|
||||
}
|
||||
|
||||
|
@ -234,7 +243,7 @@ public:
|
|||
|
||||
private:
|
||||
shared_ptr<polyfill::stop_state> m_stop_state;
|
||||
optional<polyfill::stop_state_callbacks::const_iterator> m_callback;
|
||||
polyfill::stop_state_callback m_callback;
|
||||
};
|
||||
|
||||
template <typename Callback>
|
||||
|
|
Loading…
Reference in a new issue