xrpl::TimeoutCounter Class Reference

This class is an "active" object. More...

#include <TimeoutCounter.h>

Inheritance diagram for xrpl::TimeoutCounter:

Collaboration diagram for xrpl::TimeoutCounter:

Classes
struct	QueueJobParameter

Public Member Functions
virtual void	cancel ()
	Cancel the task by marking it as failed if the task is not done.
virtual	~TimeoutCounter ()=default

Protected Types
using	ScopedLockType = std::unique_lock<std::recursive_mutex>

Protected Member Functions
	TimeoutCounter (Application &app, uint256 const &targetHash, std::chrono::milliseconds timeoutInterval, QueueJobParameter &&jobParameter, beast::Journal journal)
void	setTimer (ScopedLockType &)
	Schedule a call to queueJob() after timerInterval_.
void	queueJob (ScopedLockType &)
	Queue a job to call invokeOnTimer().
virtual void	onTimer (bool progress, ScopedLockType &)=0
	Hook called from invokeOnTimer().
virtual std::weak_ptr< TimeoutCounter >	pmDowncast ()=0
	Return a weak pointer to this.
bool	isDone () const

Protected Attributes
Application &	app_
beast::Journal	journal_
std::recursive_mutex	mtx_
uint256 const	hash_
	The hash of the object (in practice, always a ledger) we are trying to fetch.
int	timeouts_ {0}
bool	complete_ {false}
bool	failed_ {false}
bool	progress_ {false}
	Whether forward progress has been made.
std::chrono::milliseconds	timerInterval_
	The minimum time to wait between calls to execute().
QueueJobParameter	queueJobParameter_

Private Member Functions
void	invokeOnTimer ()
	Calls onTimer() if in the right state.

Private Attributes
boost::asio::basic_waitable_timer< std::chrono::steady_clock >	timer_

Detailed Description

This class is an "active" object.

It maintains its own timer and dispatches work to a job queue. Implementations derive from this class and override the abstract hook functions in the base.

This class implements an asynchronous loop:

1. The entry point is setTimer.
2. After timerInterval_, queueJob is called, which schedules a job to call invokeOnTimer (or loops back to setTimer if there are too many concurrent jobs).
3. The job queue calls invokeOnTimer which either breaks the loop if isDone or calls onTimer.
4. onTimer is the only "real" virtual method in this class. It is the callback for when the timeout expires. Generally, its only responsibility is to set failed_ = true. However, if it wants to implement a policy of retries, then it has a chance to just increment a count of expired timeouts.
5. Once onTimer returns, if the object is still not isDone, then invokeOnTimer sets another timeout by looping back to setTimer.

This loop executes concurrently with another asynchronous sequence, implemented by the subtype, that is trying to make progress and eventually set complete_ = true. While it is making progress but not complete, it should set progress_ = true, which is passed to onTimer so it can decide whether to postpone failure and reset the timeout. However, if it can complete all its work in one synchronous step (while it holds the lock), then it can ignore progress_.

Definition at line 48 of file TimeoutCounter.h.

Member Typedef Documentation

ScopedLockType

using xrpl::TimeoutCounter::ScopedLockType = std::unique_lock<std::recursive_mutex>

protected

Definition at line 65 of file TimeoutCounter.h.

Constructor & Destructor Documentation

~TimeoutCounter()

virtual xrpl::TimeoutCounter::~TimeoutCounter ( )

virtualdefault

TimeoutCounter()

xrpl::TimeoutCounter::TimeoutCounter ( Application & app, uint256 const & targetHash, std::chrono::milliseconds timeoutInterval, QueueJobParameter && jobParameter, beast::Journal journal )

protected

Definition at line 21 of file TimeoutCounter.cpp.

Member Function Documentation

cancel()

void xrpl::TimeoutCounter::cancel ( )

virtual

Cancel the task by marking it as failed if the task is not done.

Note

this function does not attempt to cancel the scheduled timer or to remove the queued job if any. When the timer expires or the queued job starts, however, the code will see that the task is done and returns immediately, if it can lock the weak pointer of the task.

Definition at line 105 of file TimeoutCounter.cpp.

setTimer()

void xrpl::TimeoutCounter::setTimer ( ScopedLockType & sl )

protected

Schedule a call to queueJob() after timerInterval_.

Definition at line 40 of file TimeoutCounter.cpp.

queueJob()

void xrpl::TimeoutCounter::queueJob ( ScopedLockType & sl )

protected

Queue a job to call invokeOnTimer().

Definition at line 58 of file TimeoutCounter.cpp.

onTimer()

virtual void xrpl::TimeoutCounter::onTimer ( bool progress, ScopedLockType &  )

protectedpure virtual

Hook called from invokeOnTimer().

Implemented in xrpl::InboundLedger, xrpl::LedgerDeltaAcquire, xrpl::LedgerReplayTask, xrpl::SkipListAcquire, and xrpl::TransactionAcquire.

pmDowncast()

virtual std::weak_ptr< TimeoutCounter > xrpl::TimeoutCounter::pmDowncast ( )

protectedpure virtual

Return a weak pointer to this.

Implemented in xrpl::InboundLedger, xrpl::LedgerDeltaAcquire, xrpl::LedgerReplayTask, xrpl::SkipListAcquire, and xrpl::TransactionAcquire.

isDone()

bool xrpl::TimeoutCounter::isDone ( ) const

protected

Definition at line 98 of file TimeoutCounter.h.

invokeOnTimer()

void xrpl::TimeoutCounter::invokeOnTimer ( )

private

Calls onTimer() if in the right state.

Only called by queueJob().

Definition at line 80 of file TimeoutCounter.cpp.

Member Data Documentation

app_

Application& xrpl::TimeoutCounter::app_

protected

Definition at line 105 of file TimeoutCounter.h.

journal_

beast::Journal xrpl::TimeoutCounter::journal_

protected

Definition at line 106 of file TimeoutCounter.h.

mtx_

std::recursive_mutex xrpl::TimeoutCounter::mtx_

mutableprotected

Definition at line 107 of file TimeoutCounter.h.

hash_

uint256 const xrpl::TimeoutCounter::hash_

protected

The hash of the object (in practice, always a ledger) we are trying to fetch.

Definition at line 111 of file TimeoutCounter.h.

timeouts_

int xrpl::TimeoutCounter::timeouts_ {0}

protected

Definition at line 112 of file TimeoutCounter.h.

complete_

bool xrpl::TimeoutCounter::complete_ {false}

protected

Definition at line 113 of file TimeoutCounter.h.

failed_

bool xrpl::TimeoutCounter::failed_ {false}

protected

Definition at line 114 of file TimeoutCounter.h.

progress_

bool xrpl::TimeoutCounter::progress_ {false}

protected

Whether forward progress has been made.

Definition at line 116 of file TimeoutCounter.h.

timerInterval_

std::chrono::milliseconds xrpl::TimeoutCounter::timerInterval_

protected

The minimum time to wait between calls to execute().

Definition at line 118 of file TimeoutCounter.h.

queueJobParameter_

QueueJobParameter xrpl::TimeoutCounter::queueJobParameter_

protected

Definition at line 120 of file TimeoutCounter.h.

timer_

boost::asio::basic_waitable_timer<std::chrono::steady_clock> xrpl::TimeoutCounter::timer_

private

Definition at line 129 of file TimeoutCounter.h.