<Thread>.SendSignal (Function)

ONLINE HELP
WINDEV, WEBDEV AND WINDEV MOBILE

Version:

Home | Sign in | English

Help

WLanguage

WLanguage functions

Standard functions

Process management functions

Threads, semaphores, signals and mutex

Prefix syntax

SendSignal

Presentation

Example

Synchronizing threads

See also

<Thread>.SendSignal (Function)

In french: <Thread>.EnvoieSignal

The current thread sends an event to the specified thread in order to unlock it. This function simplifies the synchronization between threads without having to implement an advanced management of events.

Reminder:

A thread is a process run in parallel with the current application (main thread). This allows you to run a task in the background (e.g. backup, etc.).
ThreadWaitSignal and <Thread>.SendSignal are used to synchronize the threads two by two.

Example

// Create an event
EventCreate("Let's go", eventManual, eventClose)
// Run a first thread
Thread1 is Thread(Thread_First)
ThreadExecute(Thread1)
// Locks the current thread until the event is obtained
ThreadWaitSignal()

// Run a second thread
Thread2 is Thread(Thread_Second)
ThreadExecute(Thread2)
// Locks the current thread until the event is obtained
ThreadWaitSignal()

// Modifies the event to run the threads
EventChange("Let's go", eventOpen)

//----------------------------------------------
PROCEDURE Thread_First()
Trace(dbgInfo(dbgProcess) + " - ThreadSendSignal(threadMain)")
ThreadSendSignal(threadMain)
EventWait("Let's go")
Trace(dbgInfo(dbgProcess) + " - Event received")

//--------------------------------------------
PROCEDURE Thread_Second()
Trace(dbgInfo(dbgProcess) + " - ThreadSendSignal(threadMain)")
ThreadSendSignal(threadMain)
EventWait("Let's go")
Trace(dbgInfo(dbgProcess) + " - Event received")

Syntax

Sending a signal to a thread identified by a Thread variable Hide the details

<Thread>.SendSignal()

<Thread>: Thread variable

Name of the Thread variable corresponding to the thread to which the signal must be sent.

Remarks

Synchronizing threads

ThreadWaitSignal and <Thread>.SendSignal are used to synchronize the threads two by two. To synchronize several threads on the same event, the event management functions must be used:

EventCreate: Creates an event.
<AutomaticEvent variable>.Wait: Locks the current thread and waits for the event.
EventChange: Modifies the status of an event.
EventDestroy: Destroys an event.

Remark: The internal mechanisms for managing the queues and stacks allow you not to synchronize the threads (<Queue variable>.Enqueue and <Queue variable>.Dequeue for the queues, <Stack variable>.Push and <Stack variable>.Pop for the stacks).

Business / UI classification: Neutral code

Component: wd270vm.dll