172 lines
3.2 KiB
C++
172 lines
3.2 KiB
C++
/*
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* \brief Monitored execution in main context
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* \author Christian Helmuth
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* \author Christian Prochaska
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* \date 2020-01-09
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*/
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/*
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* Copyright (C) 2020 Genode Labs GmbH
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*
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* This file is part of the Genode OS framework, which is distributed
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* under the terms of the GNU Affero General Public License version 3.
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*/
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#ifndef _LIBC__INTERNAL__MONITOR_H_
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#define _LIBC__INTERNAL__MONITOR_H_
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/* Genode includes */
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#include <base/registry.h>
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/* libc-internal includes */
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#include <internal/timer.h>
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#include <internal/types.h>
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namespace Libc { class Monitor; };
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class Libc::Monitor : Interface
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{
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public:
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struct Job;
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struct Pool;
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protected:
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struct Function : Interface { virtual bool execute() = 0; };
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virtual bool _monitor(Genode::Lock &, Function &, uint64_t) = 0;
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virtual void _charge_monitors() = 0;
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public:
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/**
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* Block until monitored execution succeeds or timeout expires
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*
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* The mutex must be locked when calling the monitor. It is released
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* during wait for completion and re-aquired before the function
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* returns. This behavior is comparable to condition variables.
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*
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* Returns true if execution completed, false on timeout.
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*/
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template <typename FN>
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bool monitor(Genode::Lock &mutex, FN const &fn, uint64_t timeout_ms = 0)
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{
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struct _Function : Function
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{
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FN const &fn;
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bool execute() override { return fn(); }
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_Function(FN const &fn) : fn(fn) { }
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} function { fn };
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return _monitor(mutex, function, timeout_ms);
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}
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/**
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* Charge monitor to execute the monitored function
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*/
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void charge_monitors() { _charge_monitors(); }
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};
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struct Libc::Monitor::Job : Timeout_handler
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{
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private:
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Monitor::Function &_fn;
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protected:
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bool _completed { false };
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bool _expired { false };
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Lock _blockade { Lock::LOCKED };
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Constructible<Timeout> _timeout;
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public:
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Job(Monitor::Function &fn,
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Timer_accessor &timer_accessor, uint64_t timeout_ms)
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: _fn(fn)
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{
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if (timeout_ms) {
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_timeout.construct(timer_accessor, *this);
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_timeout->start(timeout_ms);
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}
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}
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bool completed() const { return _completed; }
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bool expired() const { return _expired; }
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bool execute() { return _fn.execute(); }
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virtual void wait_for_completion() { _blockade.lock(); }
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virtual void complete()
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{
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_completed = true;
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_blockade.unlock();
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}
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/**
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* Timeout_handler interface
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*/
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void handle_timeout() override
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{
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_expired = true;
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_blockade.unlock();
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}
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};
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struct Libc::Monitor::Pool
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{
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private:
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Registry<Job> _jobs;
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Lock _mutex;
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bool _execution_pending { false };
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public:
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void monitor(Genode::Lock &mutex, Job &job)
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{
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Registry<Job>::Element element { _jobs, job };
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mutex.unlock();
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job.wait_for_completion();
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mutex.lock();
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}
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bool charge_monitors()
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{
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Lock::Guard guard { _mutex };
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bool const charged = !_execution_pending;
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_execution_pending = true;
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return charged;
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}
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void execute_monitors()
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{
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{
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Lock::Guard guard { _mutex };
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if (!_execution_pending) return;
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_execution_pending = false;
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}
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_jobs.for_each([&] (Job &job) {
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if (!job.completed() && !job.expired() && job.execute()) {
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job.complete();
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}
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});
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}
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};
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#endif /* _LIBC__INTERNAL__MONITOR_H_ */
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