LogCabin::Event::Timer Class Reference

A Timer is called by the Event::Loop when time has elapsed. More...

#include <Timer.h>

Inheritance diagram for LogCabin::Event::Timer:

List of all members.

Classes
class	Monitor
	Registers a Timer handler to be monitored by the Event::Loop. More...
Public Member Functions
	Timer ()
	Construct a timer but do not schedule it to trigger.
virtual	~Timer ()
	Destructor.
virtual void	handleTimerEvent ()=0
	This method is overridden by a subclass and invoked when the timer expires.
void	schedule (uint64_t nanoseconds)
	Start the timer.
void	scheduleAbsolute (Core::Time::SteadyClock::time_point timeout)
	Start the timer for an absolute point in time.
void	deschedule ()
	Stop the timer from calling handleTimerEvent().
Private Member Functions
bool	isScheduled () const
	Returns true if the timer has been scheduled and has not yet fired.
void	handleFileEvent (uint32_t events)
	Generic event handler for files.
	Timer (const Timer &)
Timer &	operator= (const Timer &)

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Detailed Description

A Timer is called by the Event::Loop when time has elapsed.

The client should inherit from this and implement the trigger method for when the timer expires.

Timers can be added and scheduled from any thread, but they will always fire on the thread running the Event::Loop.

Definition at line 37 of file Timer.h.

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Constructor & Destructor Documentation

LogCabin::Event::Timer::Timer

(

)

Construct a timer but do not schedule it to trigger.

After this is constructed, you'll want to create an Event::Timer::Monitor for it and also schedule() it, in either order.

Definition at line 57 of file Timer.cc.

LogCabin::Event::Timer::~Timer

(

)

[virtual]

Destructor.

Definition at line 62 of file Timer.cc.

LogCabin::Event::Timer::Timer

(

const Timer &

)

[private]

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Member Function Documentation

virtual void LogCabin::Event::Timer::handleTimerEvent

(

)

[pure virtual]

This method is overridden by a subclass and invoked when the timer expires.

This method will be invoked by the main event loop on whatever thread is running the Event::Loop.

Implemented in LogCabin::RPC::ClientSession::Timer, LogCabin::Event::Loop::NullTimer, and LogCabin::RPC::anonymous_namespace{ClientSession.cc}::TimerNotifier.

void LogCabin::Event::Timer::schedule

(

uint64_t

nanoseconds

)

Start the timer.

Parameters:

nanoseconds

The timer will trigger once this number of nanoseconds have elapsed. If the timer was already scheduled, the old time is forgotten.

Definition at line 67 of file Timer.cc.

void LogCabin::Event::Timer::scheduleAbsolute

(

Core::Time::SteadyClock::time_point

timeout

)

Start the timer for an absolute point in time.

If the timeout is in the past, the timer will trigger immediately once the event loop runs.

Parameters:

timeout

The timer will trigger once this timeout has past. If the timer was already scheduled, the old time is forgotten.

Definition at line 88 of file Timer.cc.

void LogCabin::Event::Timer::deschedule

(

)

Stop the timer from calling handleTimerEvent().

This will cancel the current timer, if any, so that handleTimerEvent() is not called until the next time it is scheduled.

This method behaves in a friendly way when called concurrently with the timer firing:

• If this method is called from another thread and handleTimerEvent() is running concurrently on the event loop thread, deschedule() will wait for handleTimerEvent() to complete before returning.
• If this method is called from the event loop thread and handleTimerEvent() is currently being fired, then deschedule() can't wait and returns immediately.

Definition at line 115 of file Timer.cc.

bool LogCabin::Event::Timer::isScheduled

(

)

const [private]

Returns true if the timer has been scheduled and has not yet fired.

Warning:

This is prone to races; it's primarily useful for unit tests. It also improperly returns false after scheduleAbsolute() is called with a time that has expired. It's marked as private so it can't be accessed from normal (non-test) code. TODO(ongaro): remove entirely or add additional state to this class to make this work correctly?

Returns:

True if the timer has been scheduled and will eventually call handleTimerEvent(). False if the timer is currently running handleTimerEvent() or if it is not scheduled to call handleTimerEvent() in the future.

Definition at line 125 of file Timer.cc.

void LogCabin::Event::Timer::handleFileEvent

(

uint32_t

events

)

[private, virtual]

Generic event handler for files.

Calls handleTimerEvent().

Implements LogCabin::Event::File.

Definition at line 138 of file Timer.cc.

Timer& LogCabin::Event::Timer::operator=

(

const Timer &

)

[private]

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The documentation for this class was generated from the following files:

• Event/Timer.h
• Event/Timer.cc