ThreadSendSignal (Function)

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Standard functions

Process management functions

Threads, semaphores, signals and mutex

WLanguage functions

ThreadSendSignal

Presentation

Example

Synchronizing threads

See also

ThreadSendSignal (Function)

In french: ThreadEnvoieSignal

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 ThreadSendSignal are used to synchronize the threads two by two.

Example

See additional examples

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

// Run a second thread
ThreadExecute("Thread2", threadNormal, "Thread_Second")
// 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 its name Hide the details

ThreadSendSignal(<Thread name>)

<Thread name>: Character string

Name of the thread to which the event must be sent. To send an event to the main thread, use the character string "." or the threadMain constant.
No event can be sent to the current thread.
This name is given when running the thread (ThreadExecute).

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

ThreadSendSignal(<Thread>)

<Thread>: Thread variable

Name of the Thread variable corresponding to the thread to which the signal must be sent. To send an event to the main thread, use the character string "." or the threadMain constant.
No event can be sent to the current thread.

Remarks

Synchronizing threads

ThreadWaitSignal and ThreadSendSignal 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.
EventWait: 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 (Enqueue and Dequeue for the queues, Push and Pop for the stacks).

Business / UI classification: Neutral code

Component: wd270vm.dll