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347 lines
10 KiB
C++
347 lines
10 KiB
C++
/*
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* \brief Connection to timer service and timeout scheduler
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* \author Norman Feske
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* \date 2008-08-22
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*/
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/*
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* Copyright (C) 2008-2017 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 _INCLUDE__TIMER_SESSION__CONNECTION_H_
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#define _INCLUDE__TIMER_SESSION__CONNECTION_H_
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/* Genode includes */
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#include <timer_session/client.h>
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#include <base/connection.h>
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#include <util/reconstructible.h>
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#include <base/entrypoint.h>
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#include <timer/timeout.h>
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#include <trace/timestamp.h>
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namespace Timer
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{
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class Connection;
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template <typename> class Periodic_timeout;
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template <typename> class One_shot_timeout;
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}
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/**
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* Periodic timeout that is linked to a custom handler, scheduled when constructed
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*/
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template <typename HANDLER>
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struct Timer::Periodic_timeout : private Genode::Noncopyable,
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private Genode::Timeout_handler
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{
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private:
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using Duration = Genode::Duration;
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using Timeout = Genode::Timeout;
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using Microseconds = Genode::Microseconds;
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typedef void (HANDLER::*Handler_method)(Duration);
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Timeout _timeout;
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HANDLER &_object;
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Handler_method const _method;
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/*********************
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** Timeout_handler **
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*********************/
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void handle_timeout(Duration curr_time) override {
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(_object.*_method)(curr_time); }
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public:
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Periodic_timeout(Connection &timer,
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HANDLER &object,
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Handler_method method,
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Microseconds duration)
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:
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_timeout { timer },
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_object { object },
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_method { method }
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{
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_timeout.schedule_periodic(duration, *this);
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}
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};
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/**
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* One-shot timeout that is linked to a custom handler, scheduled manually
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*/
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template <typename HANDLER>
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class Timer::One_shot_timeout : private Genode::Noncopyable,
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private Genode::Timeout_handler
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{
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private:
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using Duration = Genode::Duration;
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using Timeout = Genode::Timeout;
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using Microseconds = Genode::Microseconds;
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typedef void (HANDLER::*Handler_method)(Duration);
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Timeout _timeout;
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HANDLER &_object;
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Handler_method const _method;
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/*********************
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** Timeout_handler **
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*********************/
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void handle_timeout(Duration curr_time) override {
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(_object.*_method)(curr_time); }
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public:
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One_shot_timeout(Connection &timer,
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HANDLER &object,
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Handler_method method)
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:
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_timeout { timer },
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_object { object },
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_method { method }
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{ }
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void schedule(Microseconds duration) {
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_timeout.schedule_one_shot(duration, *this); }
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void discard() { _timeout.discard(); }
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bool scheduled() { return _timeout.scheduled(); }
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Microseconds deadline() const { return _timeout.deadline(); }
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};
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/**
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* Connection to timer service and timeout scheduler
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*
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* Multiplexes a timer session amongst different timeouts.
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*/
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class Timer::Connection : public Genode::Connection<Session>,
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public Session_client,
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private Genode::Time_source
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{
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friend class Genode::Timeout;
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private:
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using Timeout = Genode::Timeout;
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using Timeout_handler = Genode::Timeout_handler;
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using Timestamp = Genode::Trace::Timestamp;
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using Duration = Genode::Duration;
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using Mutex = Genode::Mutex;
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using Microseconds = Genode::Microseconds;
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using Milliseconds = Genode::Milliseconds;
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using Entrypoint = Genode::Entrypoint;
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using Io_signal_handler = Genode::Io_signal_handler<Connection>;
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/*
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* Noncopyable
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*/
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Connection(Connection const &);
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Connection &operator = (Connection const &);
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/*
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* The mode determines which interface of the timer connection is
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* enabled. Initially, a timer connection is in TIMER_SESSION mode.
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* In this mode, the user can operate directly on the connection using
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* the methods of the timer-session interface. As soon as the
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* connection is handed over as argument to the constructor of a
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* Periodic_timeout or a One_shot_timeout, it switches to
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* TIMEOUT_FRAMEWORK mode. From this point on, the only method that
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* the user can use directly on the connection is 'curr_time'. For
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* the rest of the functionality he rather uses the interfaces of
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* timeout objects that reference the connection.
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*
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* These are the characteristics of the two modes:
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*
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* TIMER_SESSION:
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*
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* * Allows for both blocking and non-blocking timeout semantics.
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* * Missing local interpolation leads to less precise curr_time
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* results.
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* * Only one timeout at a time per connection.
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*
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* TIMEOUT FRAMEWORK:
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*
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* * Supports only non-blocking timeout semantics.
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* * More precise curr_time results through local interpolation.
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* * Multiplexing of multiple timeouts at the same connection
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*/
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enum Mode { TIMER_SESSION, TIMEOUT_FRAMEWORK };
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Mode _mode { TIMER_SESSION };
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Mutex _mutex { };
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Genode::Signal_receiver _sig_rec { };
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Genode::Signal_context _default_sigh_ctx { };
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Genode::Signal_context_capability
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_default_sigh_cap = _sig_rec.manage(&_default_sigh_ctx);
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Genode::Signal_context_capability _custom_sigh_cap { };
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void _sigh(Signal_context_capability sigh)
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{
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Session_client::sigh(sigh);
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}
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/****************************************************
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** Members for interaction with Timeout framework **
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****************************************************/
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enum { MIN_TIMEOUT_US = 5000 };
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enum { REAL_TIME_UPDATE_PERIOD_US = 500000 };
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enum { MAX_INTERPOLATION_QUALITY = 3 };
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enum { MAX_REMOTE_TIME_LATENCY_US = 500 };
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enum { MAX_REMOTE_TIME_TRIALS = 5 };
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enum { NR_OF_INITIAL_CALIBRATIONS = 3 * MAX_INTERPOLATION_QUALITY };
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enum { MIN_FACTOR_LOG2 = 8 };
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Io_signal_handler _signal_handler;
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Timeout_handler *_handler { nullptr };
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Mutex _real_time_mutex { };
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uint64_t _us { elapsed_us() };
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Timestamp _ts { _timestamp() };
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Duration _real_time { Microseconds { _us } };
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Duration _interpolated_time { _real_time };
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unsigned _interpolation_quality { 0 };
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uint64_t _us_to_ts_factor { 1 };
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unsigned _us_to_ts_factor_shift { 0 };
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Genode::Timeout_scheduler _timeout_scheduler { *this, Microseconds { 1 } };
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Genode::Timeout_scheduler &_switch_to_timeout_framework_mode();
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Timestamp _timestamp();
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void _update_interpolation_quality(uint64_t min_factor,
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uint64_t max_factor);
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uint64_t _ts_to_us_ratio(Timestamp ts,
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uint64_t us,
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unsigned shift);
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void _update_real_time();
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Duration _update_interpolated_time(Duration &interpolated_time);
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void _handle_timeout();
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/*****************
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** Time_source **
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*****************/
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void set_timeout(Microseconds duration, Timeout_handler &handler) override;
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Microseconds max_timeout() const override { return Microseconds(REAL_TIME_UPDATE_PERIOD_US); }
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public:
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struct Method_cannot_be_used_in_timeout_framework_mode : Genode::Exception { };
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/**
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* Constructor
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*
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* \param env environment used for construction (e.g. quota trading)
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* \param ep entrypoint used as timeout handler execution context
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* \param label optional label used in session routing
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*/
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Connection(Genode::Env &env,
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Genode::Entrypoint &ep,
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Label const &label = Label());
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/**
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* Convenience constructor wrapper using the environment's entrypoint as
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* timeout handler execution context
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*/
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Connection(Genode::Env &env, Label const &label = Label())
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: Connection(env, env.ep(), label) { }
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~Connection() { _sig_rec.dissolve(&_default_sigh_ctx); }
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/*
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* Intercept 'sigh' to keep track of customized signal handlers
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*
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* \noapi
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* \deprecated Use One_shot_timeout (or Periodic_timeout) instead
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*/
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void sigh(Signal_context_capability sigh) override
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{
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if (_mode == TIMEOUT_FRAMEWORK) {
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throw Method_cannot_be_used_in_timeout_framework_mode();
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}
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_custom_sigh_cap = sigh;
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Session_client::sigh(_custom_sigh_cap);
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}
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/*
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* Block for a time span of 'us' microseconds
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*
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* \noapi
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* \deprecated Use One_shot_timeout (or Periodic_timeout) instead
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*/
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void usleep(uint64_t us) override
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{
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if (_mode == TIMEOUT_FRAMEWORK) {
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throw Method_cannot_be_used_in_timeout_framework_mode();
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}
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/*
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* Omit the interaction with the timer driver for the corner case
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* of not sleeping at all. This corner case may be triggered when
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* polling is combined with sleeping (as some device drivers do).
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* If we passed the sleep operation to the timer driver, the
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* timer would apply its policy about a minimum sleep time to
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* the sleep operation, which is not desired when polling.
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*/
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if (us == 0)
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return;
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/* serialize sleep calls issued by different threads */
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Mutex::Guard guard(_mutex);
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/* temporarily install to the default signal handler */
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if (_custom_sigh_cap.valid())
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Session_client::sigh(_default_sigh_cap);
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/* trigger timeout at default signal handler */
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trigger_once(us);
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_sig_rec.wait_for_signal();
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/* revert custom signal handler if registered */
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if (_custom_sigh_cap.valid())
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Session_client::sigh(_custom_sigh_cap);
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}
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/*
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* Block for a time span of 'ms' milliseconds
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*
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* \noapi
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* \deprecated Use One_shot_timeout (or Periodic_timeout) instead
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*/
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void msleep(uint64_t ms) override
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{
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if (_mode == TIMEOUT_FRAMEWORK) {
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throw Method_cannot_be_used_in_timeout_framework_mode();
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}
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usleep(1000*ms);
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}
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/*****************
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** Time_source **
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*****************/
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Duration curr_time() override;
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};
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#endif /* _INCLUDE__TIMER_SESSION__CONNECTION_H_ */
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