Operator Reference

HALCON Operator Reference / System / Multithreading

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create_message_queueT_create_message_queueCreateMessageQueueCreateMessageQueuecreate_message_queue (Operator)

create_message_queueT_create_message_queueCreateMessageQueueCreateMessageQueuecreate_message_queue — Create a new empty message queue.

Signature

create_message_queue( : : : QueueHandle)

Herror T_create_message_queue(Htuple* QueueHandle)

void CreateMessageQueue(HTuple* QueueHandle)

void HMessageQueue::HMessageQueue()

void HMessageQueue::CreateMessageQueue()

static void HOperatorSet.CreateMessageQueue(out HTuple queueHandle)

public HMessageQueue()

void HMessageQueue.CreateMessageQueue()

def create_message_queue() -> HHandle

Description

create_message_queuecreate_message_queueCreateMessageQueueCreateMessageQueuecreate_message_queue creates a new empty message queue. The output parameter QueueHandleQueueHandleQueueHandlequeueHandlequeue_handle is a handle to the newly created message queue and is used to identify the queue in any subsequent operator calls using the queue.

The message queues are designed as FIFO pipes delivering arbitrary sets of data safely among different threads. The queue access is internally fully synchronized, no explicit locking is required from the application. The data is traveling through the queue in so called messages (see create_messagecreate_messageCreateMessageCreateMessagecreate_message).

Multiple producer threads can append data simultaneously (enqueue_messageenqueue_messageEnqueueMessageEnqueueMessageenqueue_message) while multiple consumer threads are simultaneously retrieving the data again (dequeue_messagedequeue_messageDequeueMessageDequeueMessagedequeue_message). Multiple messages can be enqueued together using a single enqueue_messageenqueue_messageEnqueueMessageEnqueueMessageenqueue_message operation. In such case, those messages will travel together through the queue and will be delivered through a single dequeue_messagedequeue_messageDequeueMessageDequeueMessagedequeue_message call.

All the enqueued messages are copied by the enqueue_messageenqueue_messageEnqueueMessageEnqueueMessageenqueue_message operation. The original message(s) can thus be immediately reused after the enqueue_messageenqueue_messageEnqueueMessageEnqueueMessageenqueue_message call without affecting the enqueued copy.

Execution Information

• Multithreading type: reentrant (runs in parallel with non-exclusive operators).
• Multithreading scope: global (may be called from any thread).
• Processed without parallelization.

Parameters

QueueHandleQueueHandleQueueHandlequeueHandlequeue_handle (output_control)  message_queue → HMessageQueue, HTupleHHandleHTupleHtuple (handle) (IntPtr) (HHandle) (handle)

Handle of the newly created message queue.

Number of elements: QueueHandle == 1

Assertion: QueueHandle != 0

Example (HDevelop)

create_message_queue (ProducerQueue)
create_message_queue (ResultQueue)
* ...

Result

Returns 2 ( H_MSG_TRUE) unless a resource allocation error occurs. Otherwise an exception is raised.

Possible Successors

enqueue_messageenqueue_messageEnqueueMessageEnqueueMessageenqueue_message, dequeue_messagedequeue_messageDequeueMessageDequeueMessagedequeue_message

See also

clear_message_queueclear_message_queueClearMessageQueueClearMessageQueueclear_message_queue, enqueue_messageenqueue_messageEnqueueMessageEnqueueMessageenqueue_message, dequeue_messagedequeue_messageDequeueMessageDequeueMessagedequeue_message, set_message_queue_paramset_message_queue_paramSetMessageQueueParamSetMessageQueueParamset_message_queue_param, get_message_queue_paramget_message_queue_paramGetMessageQueueParamGetMessageQueueParamget_message_queue_param, create_messagecreate_messageCreateMessageCreateMessagecreate_message, clear_messageclear_messageClearMessageClearMessageclear_message, set_message_tupleset_message_tupleSetMessageTupleSetMessageTupleset_message_tuple, get_message_tupleget_message_tupleGetMessageTupleGetMessageTupleget_message_tuple, set_message_objset_message_objSetMessageObjSetMessageObjset_message_obj, get_message_objget_message_objGetMessageObjGetMessageObjget_message_obj

Module

Foundation

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ClassesClasses | | Operators