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#ifndef MBGL_UTIL_RUN_LOOP
#define MBGL_UTIL_RUN_LOOP
#include <mbgl/util/noncopyable.hpp>
#include <mbgl/util/util.hpp>
#include <mbgl/util/work_task.hpp>
#include <mbgl/util/work_request.hpp>
#include <functional>
#include <utility>
#include <queue>
#include <mutex>
#include <atomic>
namespace mbgl {
namespace util {
typedef void * LOOP_HANDLE;
class RunLoop : private util::noncopyable {
public:
enum class Type : uint8_t {
Default,
New,
};
enum class Event : uint8_t {
None = 0,
Read = 1,
Write = 2,
ReadWrite = Read | Write,
};
RunLoop(Type type = Type::Default);
~RunLoop();
static RunLoop* Get();
static LOOP_HANDLE getLoopHandle();
void run();
void runOnce();
void stop();
// So far only needed by the libcurl backend.
void addWatch(int fd, Event, std::function<void(int, Event)>&& callback);
void removeWatch(int fd);
// Invoke fn(args...) on this RunLoop.
template <class Fn, class... Args>
void invoke(Fn&& fn, Args&&... args) {
auto tuple = std::make_tuple(std::move(args)...);
auto task = std::make_shared<Invoker<Fn, decltype(tuple)>>(
std::move(fn),
std::move(tuple));
push(task);
}
// Post the cancellable work fn(args...) to this RunLoop.
template <class Fn, class... Args>
std::unique_ptr<AsyncRequest>
invokeCancellable(Fn&& fn, Args&&... args) {
auto flag = std::make_shared<std::atomic<bool>>();
*flag = false;
auto tuple = std::make_tuple(std::move(args)...);
auto task = std::make_shared<Invoker<Fn, decltype(tuple)>>(
std::move(fn),
std::move(tuple),
flag);
push(task);
return std::make_unique<WorkRequest>(task);
}
// Invoke fn(args...) on this RunLoop, then invoke callback(results...) on the current RunLoop.
template <class Fn, class Cb, class... Args>
std::unique_ptr<AsyncRequest>
invokeWithCallback(Fn&& fn, Cb&& callback, Args&&... args) {
auto flag = std::make_shared<std::atomic<bool>>();
*flag = false;
// Create a lambda L1 that invokes another lambda L2 on the current RunLoop R, that calls
// the callback C. Both lambdas check the flag before proceeding. L1 needs to check the flag
// because if the request was cancelled, then R might have been destroyed. L2 needs to check
// the flag because the request may have been cancelled after L2 was invoked but before it
// began executing.
auto after = [flag, current = RunLoop::Get(), callback1 = std::move(callback)] (auto&&... results1) {
if (!*flag) {
current->invoke([flag, callback2 = std::move(callback1)] (auto&&... results2) {
if (!*flag) {
callback2(std::move(results2)...);
}
}, std::move(results1)...);
}
};
auto tuple = std::make_tuple(std::move(args)..., after);
auto task = std::make_shared<Invoker<Fn, decltype(tuple)>>(
std::move(fn),
std::move(tuple),
flag);
push(task);
return std::make_unique<WorkRequest>(task);
}
private:
MBGL_STORE_THREAD(tid)
template <class F, class P>
class Invoker : public WorkTask {
public:
Invoker(F&& f, P&& p, std::shared_ptr<std::atomic<bool>> canceled_ = nullptr)
: canceled(std::move(canceled_)),
func(std::move(f)),
params(std::move(p)) {
}
void operator()() override {
// Lock the mutex while processing so that cancel() will block.
std::lock_guard<std::recursive_mutex> lock(mutex);
if (!canceled || !*canceled) {
invoke(std::make_index_sequence<std::tuple_size<P>::value>{});
}
}
// If the task has not yet begun, this will cancel it.
// If the task is in progress, this will block until it completed. (Currently
// necessary because of shared state, but should be removed.) It will also
// cancel the after callback.
// If the task has completed, but the after callback has not executed, this
// will cancel the after callback.
// If the task has completed and the after callback has executed, this will
// do nothing.
void cancel() override {
std::lock_guard<std::recursive_mutex> lock(mutex);
*canceled = true;
}
private:
template <std::size_t... I>
void invoke(std::index_sequence<I...>) {
func(std::move(std::get<I>(std::forward<P>(params)))...);
}
std::recursive_mutex mutex;
std::shared_ptr<std::atomic<bool>> canceled;
F func;
P params;
};
using Queue = std::queue<std::shared_ptr<WorkTask>>;
void push(std::shared_ptr<WorkTask>);
void withMutex(std::function<void()>&& fn) {
std::lock_guard<std::mutex> lock(mutex);
fn();
}
void process() {
Queue queue_;
withMutex([&] { queue_.swap(queue); });
while (!queue_.empty()) {
(*(queue_.front()))();
queue_.pop();
}
}
Queue queue;
std::mutex mutex;
class Impl;
std::unique_ptr<Impl> impl;
};
} // namespace util
} // namespace mbgl
#endif
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