X-Git-Url: https://git.sesse.net/?a=blobdiff_plain;f=common%2Ffuture.h;h=12c0bfc603dacd78d2810fad32721b4b6622a6ef;hb=bb04ef30e802fa58550a0dec7b54e61aeefb0c7e;hp=7ee9da4fd31b8e2ce6fde8e560f2a67cb078f33f;hpb=58dbff2c53cb764095a301131416080afcbcfbf9;p=casparcg

diff --git a/common/future.h b/common/future.h
index 7ee9da4fd..12c0bfc60 100644
--- a/common/future.h
+++ b/common/future.h
@@ -1,185 +1,177 @@
-#pragma once
-
-#include "enum_class.h"
-
-#include <boost/thread/future.hpp>
-#include <boost/thread/thread.hpp>
-#include <boost/shared_ptr.hpp>
-
-#include <functional>
-
-namespace caspar {
-	
-struct launch_policy_def
-{
-	enum type
-	{
-		async = 1,
-		deferred = 2
-	};
-};
-typedef caspar::enum_class<launch_policy_def> launch;
-
-namespace detail {
-	
-template<typename R>
-struct future_object_helper
-{	
-	template<typename T, typename F>
-	static void nonlocking_invoke(T& future_object, F& f)
-	{				
-        try
-        {
-			future_object.mark_finished_with_result_internal(f());
-        }
-        catch(...)
-        {
-			future_object.mark_exceptional_finish_internal(boost::current_exception());
-        }
-	}
-
-	template<typename T, typename F>
-	static void locking_invoke(T& future_object, F& f)
-	{				
-        try
-        {
-			future_object.mark_finished_with_result(f());
-        }
-        catch(...)
-        {
-			future_object.mark_exceptional_finish();
-        }
-	}
-};
-
-template<>
-struct future_object_helper<void>
-{	
-	template<typename T, typename F>
-	static void nonlocking_invoke(T& future_object, F& f)
-	{				
-        try
-        {
-			f();
-			future_object.mark_finished_with_result_internal();
-        }
-        catch(...)
-        {
-			future_object.mark_exceptional_finish_internal(boost::current_exception());
-        }
-	}
-
-	template<typename T, typename F>
-	static void locking_invoke(T& future_object, F& f)
-	{				
-        try
-        {
-			f();
-			future_object.mark_finished_with_result();
-        }
-        catch(...)
-        {
-			future_object.mark_exceptional_finish();
-        }
-	}
-};
-
-template<typename R, typename F>
-struct deferred_future_object : public boost::detail::future_object<R>
-{	
-	F f;
-	bool done;
-
-	template<typename F2>
-	deferred_future_object(F2&& f)
-		: f(std::forward<F2>(f))
-		, done(false)
-	{
-		set_wait_callback(std::mem_fn(&detail::deferred_future_object<R, F>::operator()), this);
-	}
-		
-	void operator()()
-	{		
-		boost::lock_guard<boost::mutex> lock2(mutex);
-
-		if(done)
-			return;
-
-		future_object_helper<R>::nonlocking_invoke(*this, f);
-
-		done = true;
-	}
-};
-
-template<typename R, typename F>
-struct async_future_object : public boost::detail::future_object<R>
-{	
-	F f;
-	boost::thread thread;
-
-	template<typename F2>
-	async_future_object(F2&& f)
-		: f(std::forward<F2>(f))
-		, thread([this]{run();})
-	{
-	}
-
-	~async_future_object()
-	{
-		thread.join();
-	}
-
-	void run()
-	{
-		future_object_helper<R>::locking_invoke(*this, f);
-	}
-};
-
-}
-	
-template<typename F>
-auto async(launch policy, F&& f) -> boost::unique_future<decltype(f())>
-{		
-	typedef decltype(f())								result_type;	
-	typedef boost::detail::future_object<result_type>	future_object_type;
-
-	boost::shared_ptr<future_object_type> future_object;
-
-	if((policy & launch::async) != 0)
-		future_object = boost::static_pointer_cast<future_object_type>(boost::make_shared<detail::async_future_object<result_type, F>>(std::forward<F>(f)));
-	else if((policy & launch::deferred) != 0)
-		future_object = boost::static_pointer_cast<future_object_type>(boost::make_shared<detail::deferred_future_object<result_type, F>>(std::forward<F>(f)));	
-	else
-		throw std::invalid_argument("policy");
-	
-	boost::unique_future<result_type> future;
-
-	static_assert(sizeof(future) == sizeof(future_object), "");
-
-	reinterpret_cast<boost::shared_ptr<future_object_type>&>(future) = std::move(future_object); // Get around the "private" encapsulation.
-	return std::move(future);
-}
-	
-template<typename F>
-auto async(F&& f) -> boost::unique_future<decltype(f())>
-{	
-	return async(launch::async | launch::deferred, std::forward<F>(f));
-}
-
-template<typename T>
-auto make_shared(boost::unique_future<T>&& f) -> boost::shared_future<T>
-{	
-	return boost::shared_future<T>(std::move(f));
-}
-
-template<typename T>
-auto flatten(boost::unique_future<T>&& f) -> boost::unique_future<decltype(f.get().get())>
-{
-	auto shared_f = make_shared(std::move(f));
-	return async(launch::deferred, [=]() mutable
-	{
-		return shared_f.get().get();
-	});
-}
-
+#pragma once
+
+#include <boost/thread/mutex.hpp>
+#include <boost/function.hpp>
+#include <boost/optional.hpp>
+
+#include <functional>
+#include <future>
+
+namespace caspar {
+
+template<typename T>
+auto flatten(std::future<T>&& f) -> std::future<typename std::decay<decltype(f.get().get())>::type>
+{
+	auto shared_f = f.share();
+	return std::async(std::launch::deferred, [=]() mutable -> typename std::decay<decltype(f.get().get())>::type
+	{
+		return shared_f.get().get();
+	});
+}
+
+template<typename F>
+bool is_ready(const F& future)
+{
+	return future.wait_for(std::chrono::seconds(0)) == std::future_status::ready;
+}
+
+/**
+ * A utility that helps the producer side of a future when the task is not
+ * able to complete immediately but there are known retry points in the code.
+ */
+template<class R>
+class retry_task
+{
+public:
+	typedef boost::function<boost::optional<R> ()> func_type;
+	
+	retry_task() : done_(false) {}
+
+	/**
+	 * Reset the state with a new task. If the previous task has not completed
+	 * the old one will be discarded.
+	 *
+	 * @param func The function that tries to calculate future result. If the
+	 *             optional return value is set the future is marked as ready.
+	 */
+	void set_task(const func_type& func)
+	{
+		boost::unique_lock<boost::mutex> lock(mutex_);
+
+		func_ = func;
+		done_ = false;
+		promise_ = std::promise<R>();
+	}
+
+	/**
+	 * Take ownership of the future for the current task. Cannot only be called
+	 * once for each task.
+	 *
+	 * @return the future.
+	 */
+	std::future<R> get_future()
+	{
+		boost::unique_lock<boost::mutex> lock(mutex_);
+
+		return promise_.get_future();
+	}
+
+	/**
+	 * Call this when it is guaranteed or probable that the task will be able
+	 * to complete.
+	 *
+	 * @return true if the task completed (the future will have a result).
+	 */
+	bool try_completion()
+	{
+		boost::unique_lock<boost::mutex> lock(mutex_);
+
+		return try_completion_internal();
+	}
+
+	/**
+	 * Call this when it is certain that the result should be ready, and if not
+	 * it should be regarded as an unrecoverable error (retrying again would
+	 * be useless), so the future will be marked as failed.
+	 *
+	 * @param exception The exception to mark the future with *if* the task
+	 *                  completion fails.
+	 */
+	template <class E>
+	void try_or_fail(const E& exception)
+	{
+		boost::unique_lock<boost::mutex> lock(mutex_);
+
+		if (!try_completion_internal())
+		{
+			try
+			{
+				throw exception;
+			}
+			catch (...)
+			{
+				CASPAR_LOG_CURRENT_EXCEPTION();
+				promise_.set_exception(std::current_exception());
+				done_ = true;
+			}
+		}
+	}
+private:
+	bool try_completion_internal()
+	{
+		if (!func_)
+			return false;
+
+		if (done_)
+			return true;
+
+		boost::optional<R> result;
+
+		try
+		{
+			result = func_();
+		}
+		catch (...)
+		{
+			CASPAR_LOG_CURRENT_EXCEPTION();
+			promise_.set_exception(std::current_exception());
+			done_ = true;
+
+			return true;
+		}
+
+		if (result)
+		{
+			promise_.set_value(*result);
+			done_ = true;
+		}
+
+		return done_;
+	}
+private:
+	boost::mutex mutex_;
+	func_type func_;
+	std::promise<R> promise_;
+	bool done_;
+};
+
+/**
+ * Wrap a value in a future with an already known result.
+ * <p>
+ * Useful when the result of an operation is already known at the time of
+ * calling.
+ *
+ * @param value The r-value to wrap.
+ *
+ * @return The future with the result set.
+ */
+template<class R>
+std::future<R> make_ready_future(R&& value)
+{
+	std::promise<R> p;
+
+	p.set_value(value);
+
+	return p.get_future();
+}
+
+static std::future<void> make_ready_future()
+{
+	std::promise<void> p;
+
+	p.set_value();
+
+	return p.get_future();
+}
+
 }
\ No newline at end of file