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/*
==============================================================================
This file is part of the JUCE library.
Copyright (c) 2022 - Raw Material Software Limited
JUCE is an open source library subject to commercial or open-source
licensing.
By using JUCE, you agree to the terms of both the JUCE 7 End-User License
Agreement and JUCE Privacy Policy.
End User License Agreement: www.juce.com/juce-7-licence
Privacy Policy: www.juce.com/juce-privacy-policy
Or: You may also use this code under the terms of the GPL v3 (see
www.gnu.org/licenses).
JUCE IS PROVIDED "AS IS" WITHOUT ANY WARRANTY, AND ALL WARRANTIES, WHETHER
EXPRESSED OR IMPLIED, INCLUDING MERCHANTABILITY AND FITNESS FOR PURPOSE, ARE
DISCLAIMED.
==============================================================================
*/
namespace juce
{
/** Manages a set of ChildProcesses and periodically checks their return value. Upon completion
it calls listeners added with addChildProcessExitedListener().
This class is mostly aimed for usage on Linux, where terminated child processes are only
cleaned up if their return code is read after termination. In order to ensure this one needs
to call ChildProcess::isFinished() until it returns false or
ChildProcess::waitForProcessToFinish() until it returns true.
This class will keep querying the return code on a Timer thread until the process
terminates. This can be handy if one wants to start and stop multiple ChildProcesses on
Linux that could take a long time to complete.
Since this class uses a Timer to check subprocess status, it's generally only safe to
access the returned ChildProcesses from the message thread.
@see ChildProcessManagerSingleton
@tags{Events}
*/
class JUCE_API ChildProcessManager final : private DeletedAtShutdown
{
public:
#ifndef DOXYGEN
JUCE_DECLARE_SINGLETON_SINGLETHREADED_MINIMAL (ChildProcessManager)
#endif
/** Creates a new ChildProcess and starts it with the provided arguments.
The arguments are the same as the overloads to ChildProcess::start().
The manager will keep the returned ChildProcess object alive until it terminates and its
return value has been queried. Calling ChildProcess::kill() on the returned object will
eventually cause its removal from the ChildProcessManager after it terminates.
*/
template <typename... Args>
std::shared_ptr<ChildProcess> createAndStartManagedChildProcess (Args&&... args)
{
auto p = std::make_shared<ChildProcess>();
if (! p->start (std::forward<Args> (args)...))
return nullptr;
processes.insert (p);
timer.startTimer (1000);
return p;
}
/** Registers a callback function that is called for every ChildProcess that terminated.
This registration is deleted when the returned ErasedScopedGuard is deleted.
*/
auto addChildProcessExitedListener (std::function<void (ChildProcess*)> listener)
{
return listeners.addListener (std::move (listener));
}
/** Returns true if the ChildProcessManager contains any running ChildProcesses that it's
monitoring.
*/
auto hasRunningProcess() const
{
return timer.isTimerRunning();
}
private:
ChildProcessManager() = default;
~ChildProcessManager() override { clearSingletonInstance(); }
void checkProcesses();
std::set<std::shared_ptr<ChildProcess>> processes;
detail::CallbackListenerList<ChildProcess*> listeners;
TimedCallback timer { [this] { checkProcesses(); } };
};
} // namespace juce
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