BluezQt 5.109.0
Public Types | Properties | Public Slots | Public Member Functions | Protected Slots | Protected Member Functions | List of all members
BluezQt::Jobabstract

This class represents an asynchronous job performed by BluezQt, it is usually not used directly but instead it is inherit by some other class. More...

#include <BluezQt/Job>

Public Types

enum  Error { NoError = 0 , UserDefinedError = 100 }
 Error type. More...
 

Properties

int error
 
QString errorText
 
bool finished
 
bool running
 

Public Slots

void kill ()
 Kills the job.
 
void start ()
 Starts the job asynchronously.
 

Public Member Functions

 Job (QObject *parent=nullptr)
 Creates a new Job object.
 
 ~Job () override
 Destroys a Job object.
 
int error () const
 Returns the error code, if there has been an error.
 
QString errorText () const
 Returns the error text if there has been an error.
 
bool exec ()
 Executes the job synchronously.
 
bool isFinished () const
 Returns whether the job have already finished.
 
bool isRunning () const
 Returns whether the job is currently running.
 

Protected Slots

virtual void doStart ()=0
 Implementation for start() that will be executed in next loop.
 

Protected Member Functions

virtual void doEmitResult ()=0
 Implementation for emitting the result signal.
 
void emitResult ()
 Utility function to emit the result signal, and suicide this job.
 
void setError (int errorCode)
 Sets the error code.
 
void setErrorText (const QString &errorText)
 Sets the error text.
 

Detailed Description

This class represents an asynchronous job performed by BluezQt, it is usually not used directly but instead it is inherit by some other class.

There are two ways of using this class, one is via exec() which will block the thread until a result is fetched, the other is via connecting to the signal result()

Please, think twice before using exec(), it should be used only in either unittest or cli apps.

Note
Job and its subclasses are meant to be used in a fire-and-forget way. Jobs will delete themselves when they finish using deleteLater().
Even given their asynchronous nature, Jobs are still executed in the main thread, so any blocking code executed in it will block the app calling it.
See also
InitManagerJob
InitObexManagerJob

Member Enumeration Documentation

◆ Error

Error type.

See also
error() const
Enumerator
NoError 

Indicates there is no error.

UserDefinedError 

Subclasses should define error codes starting at this value.

Constructor & Destructor Documentation

◆ Job()

BluezQt::Job::Job ( QObject *  parent = nullptr)
explicit

Creates a new Job object.

Parameters
parent

◆ ~Job()

BluezQt::Job::~Job ( )
override

Destroys a Job object.

Member Function Documentation

◆ doEmitResult()

virtual void BluezQt::Job::doEmitResult ( )
protectedpure virtual

Implementation for emitting the result signal.

This function is needed to be able to emit result() signal with the job pointer's type being subclass

◆ doStart

virtual void BluezQt::Job::doStart ( )
protectedpure virtualslot

Implementation for start() that will be executed in next loop.

This slot is always called in the next loop, triggered by start().

When implementing this method is important to remember that jobs are not executed on a different thread (unless done that way), so any blocking task has to be done in a different thread or process.

◆ emitResult()

void BluezQt::Job::emitResult ( )
protected

Utility function to emit the result signal, and suicide this job.

Note
Deletes this job using deleteLater().
See also
result() const

◆ error()

int BluezQt::Job::error ( ) const

Returns the error code, if there has been an error.

Make sure to call this once result() has been emitted

Returns
the error code for this job, 0 if no error.

◆ errorText()

QString BluezQt::Job::errorText ( ) const

Returns the error text if there has been an error.

Only call if error is not 0.

This is usually some extra data associated with the error, such as a URL. Use errorString() to get a human-readable, translated message.

Returns
a string to help understand the error

◆ exec()

bool BluezQt::Job::exec ( )

Executes the job synchronously.

This will start a nested QEventLoop internally. Nested event loop can be dangerous and can have unintended side effects, you should avoid calling exec() whenever you can and use the asynchronous interface of Job instead.

Should you indeed call this method, you need to make sure that all callers are reentrant, so that events delivered by the inner event loop don't cause non-reentrant functions to be called, which usually wreaks havoc.

Note that the event loop started by this method does not process user input events, which means your user interface will effectively be blocked. Other events like paint or network events are still being processed. The advantage of not processing user input events is that the chance of accidental reentrancy is greatly reduced. Still you should avoid calling this function.

Warning
This method blocks until the job finishes!
Returns
true if the job has been executed without error, false otherwise

◆ isFinished()

bool BluezQt::Job::isFinished ( ) const

Returns whether the job have already finished.

Returns
true if the job already finished

◆ isRunning()

bool BluezQt::Job::isRunning ( ) const

Returns whether the job is currently running.

Returns
true if the job is running

◆ kill

void BluezQt::Job::kill ( )
slot

Kills the job.

This method will kill the job and then call deleteLater(). Only jobs started with start() can be killed.

It will not emit result signal.

◆ setError()

void BluezQt::Job::setError ( int  errorCode)
protected

Sets the error code.

It should be called when an error is encountered in the job, just before calling emitResult().

You should define an enum of error codes, with values starting at Job::UserDefinedError, and use those. For example:

enum ExampleErrors{
InvalidFoo = UserDefinedError,
BarNotFound
};
@ UserDefinedError
Subclasses should define error codes starting at this value.
Definition job.h:74
Parameters
errorCodethe error code
See also
emitResult()

◆ setErrorText()

void BluezQt::Job::setErrorText ( const QString &  errorText)
protected

Sets the error text.

It should be called when an error is encountered in the job, just before calling emitResult().

Provides extra information about the error that cannot be determined directly from the error code. For example, a URL or filename. This string is not normally translatable.

Parameters
errorTextthe error text
See also
emitResult(), setError()

◆ start

void BluezQt::Job::start ( )
slot

Starts the job asynchronously.

This method will schedule doStart() to be executed in the next loop. This is done so this method returns as soon as possible.

When the job is finished, result() is emitted.