mongo::BackgroundJob Class Reference

#include <background.h>

Inheritance diagram for mongo::BackgroundJob:

[legend]

List of all members.

Public Types
enum	State { NotStarted, Running, Done }
Public Member Functions
State	getState () const
BackgroundJob &	go ()
bool	running () const
bool	wait (unsigned msTimeOut=0)
virtual	~BackgroundJob ()
Protected Member Functions
	BackgroundJob (bool selfDelete=false)
virtual string	name () const =0
virtual void	run ()=0
Private Member Functions
void	jobBody (boost::shared_ptr< JobStatus > status)
Private Attributes
boost::shared_ptr< JobStatus >	_status

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Detailed Description

Background thread dispatching. subclass and define run()

It is ok to call go(), that is, run the job, more than once -- if the previous invocation has finished. Thus one pattern of use is to embed a backgroundjob in your object and reuse it (or same thing with inheritance). Each go() call spawns a new thread.

Thread safety: note when job destructs, the thread is not terminated if still running. generally if the thread could still be running, allocate the job dynamically and set deleteSelf to true.

go() and wait() are not thread safe run() will be executed on the background thread BackgroundJob object must exist for as long the background thread is running

Definition at line 41 of file util/background.h.

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Member Enumeration Documentation

enum mongo::BackgroundJob::State

Enumerator:

NotStarted
Running
Done

Definition at line 66 of file util/background.h.

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Constructor & Destructor Documentation

mongo::BackgroundJob::BackgroundJob

(

bool

selfDelete = false

)

[explicit, protected]

sub-class must intantiate the BackgrounJob

Parameters:

selfDelete

if set to true, object will destruct itself after the run() finished

Note:

selfDelete instantes cannot be wait()-ed upon

virtual mongo::BackgroundJob::~BackgroundJob

(

)

[inline, virtual]

Definition at line 72 of file util/background.h.

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Member Function Documentation

State mongo::BackgroundJob::getState

(

)

const

BackgroundJob& mongo::BackgroundJob::go

(

)

starts job. returns immediatelly after dispatching.

Note:

the BackgroundJob object must live for as long the thread is still running, ie until getState() returns Done.

void mongo::BackgroundJob::jobBody

(

boost::shared_ptr< JobStatus >

status

)

[private]

virtual string mongo::BackgroundJob::name

(

)

const [protected, pure virtual]

Implemented in mongo::ClientCursorMonitor, mongo::_MultiCommandJob, mongo::SnapshotThread, mongo::Balancer, mongo::WriteBackListener, mongo::task::Server, and mongo::task::Task.

virtual void mongo::BackgroundJob::run

(

)

[protected, pure virtual]

define this to do your work. after this returns, state is set to done. after this returns, deleted if deleteSelf true.

NOTE: if run() throws, the exception will be caught within 'this' object and will ultimately lead to the BackgroundJob's thread being finished, as if run() returned.

Implemented in mongo::ClientCursorMonitor, mongo::_MultiCommandJob, mongo::SnapshotThread, mongo::Balancer, mongo::WriteBackListener, and mongo::task::Task.

bool mongo::BackgroundJob::running

(

)

const

bool mongo::BackgroundJob::wait

(

unsigned

msTimeOut = 0

)

wait for completion.

Parameters:

msTimeOut

maximum amount of time to wait in millisecons

Returns:

true if did not time out. false otherwise.

Note:

you can call wait() more than once if the first call times out. but you cannot call wait on a self-deleting job.

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Member Data Documentation

boost::shared_ptr<JobStatus> mongo::BackgroundJob::_status [private]

Definition at line 99 of file util/background.h.

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

• util/background.h