net_instaweb::Function Class Reference

#include "function.h"

Inheritance diagram for net_instaweb::Function:

Public Member Functions
void	set_quit_requested_pointer (AtomicBool *x)
bool	quit_requested () const
void	CallRun ()
void	CallCancel ()
void	set_delete_after_callback (bool x)
void	Reset ()

Protected Member Functions
virtual void	Run ()=0
virtual void	Cancel ()

Detailed Description

Encapsulates a task to be run in response to some event, such as a Timer callback, an fetch, or a cache lookup.

Users of interfaces requiring a Function* can either derive a new class from Function, or use one of the helper template-classes or MakeFunction variants below, which create delayed calls to class methods.

Note that Functions by default are self-deleting after call, but you can override that with set_delete_after_callback(false).

A Function will always have its Run method or its Cancel method called, never both. A Function should never be deleted without its Run/Cancel method being called (except if set_delete_after_callback(false)).

Note that classes calling Functions use the CallRun or CallCancel methods, rather than calling Run or Cancel directly. This allows the Function class to enforce policy on making run & cancel mutually exclusive and implement delete-after-run.

Member Function Documentation

void net_instaweb::Function::CallRun

(

)

Implementors of Function interfaces should call via these helper methods to initiate Run and Cancel callbacks. This helps centralize deletion of callbacks after they are called.

virtual void net_instaweb::Function::Cancel ( )

inlineprotectedvirtual

Informs a the Function that it is being shut down. If this is called, Run() should not be called. This should never be called while a function is running. See also set_quit_requested(), which can be called during Run(), so that Run() implementations can check quit_requested() at their convenience to stop the operation in progress.

Reimplemented in net_instaweb::MemberFunction4< C, T1, T2, T3, T4 >, net_instaweb::MemberFunction3< C, T1, T2, T3 >, net_instaweb::SchedulerBlockingFunction, net_instaweb::MemberFunction2< C, T1, T2 >, net_instaweb::MemberFunction1< C, T1 >, net_instaweb::MemberFunction0< C >, net_instaweb::QueuedWorkerPool::Sequence::AddFunction, net_instaweb::CentralControllerCallback< TransactionContext >, net_instaweb::CentralControllerCallback< ExpensiveOperationContext >, net_instaweb::CentralControllerCallback< ScheduleRewriteContext >, net_instaweb::WorkerTestBase::CountFunction, and net_instaweb::NotifyFunction.

bool net_instaweb::Function::quit_requested ( ) const

inline

Allows an infrastructure (e.g. Worker or Alarm) to request that a running Function stop soon, as it is being shut down.

This can should only be called during the Run() method.

void net_instaweb::Function::Reset

(

)

Clears the state of the function so that it can be called or cancelled again. This only makes sense to call if set_delete_after_callback(false) has been called.

virtual void net_instaweb::Function::Run ( )

protectedpure virtual

Callers must override this to define the action to take when a closure is run. If this is called, Cancel() should not be called. This is a convention that's expected of callers of Function objects, but is not enforced by the Function implementation.

Implemented in net_instaweb::RewriteDriverFactory::Deleter< T >, net_instaweb::MemberFunction4< C, T1, T2, T3, T4 >, net_instaweb::MemberFunction3< C, T1, T2, T3 >, net_instaweb::SchedulerBlockingFunction, net_instaweb::MemberFunction2< C, T1, T2 >, net_instaweb::MemberFunction1< C, T1 >, net_instaweb::MemberFunction0< C >, net_instaweb::DeleteNotifyFunction, net_instaweb::WorkerTestBase::WaitRunFunction, net_instaweb::WorkerTestBase::NotifyRunFunction, net_instaweb::QueuedWorkerPool::Sequence::AddFunction, net_instaweb::CentralControllerCallback< TransactionContext >, net_instaweb::CentralControllerCallback< ExpensiveOperationContext >, net_instaweb::CentralControllerCallback< ScheduleRewriteContext >, net_instaweb::WorkerTestBase::CountFunction, and net_instaweb::NotifyFunction.

void net_instaweb::Function::set_delete_after_callback ( bool  x )

inline

By default, Functions delete themselves after being called. Call this method to override. If the Function is going to be re-called, Reset() must be called on it first. Will not take effect if called within Run() or Cancel().

void net_instaweb::Function::set_quit_requested_pointer ( AtomicBool *  x )

inline

Functions used as Worker tasks can help the system shut down cleanly by calling quit_requested() periodically. To support this, Worker calls set_quit_requested_pointer so the Function object can access the atomic bool.

Note that a strategy of allocating the AtomicBool inside the Function object exposes a shutdown race when the function completes and deletes itself.

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

• pagespeed/kernel/base/function.h