Queue library for LabVIEW
Open and run the Example.vi to see how to use this Queue library in LabVIEW.
This example demonstrates basic queue communication with a main loop and multiple sub-threads. Refer to the diagram labels for more information.
The Queue library contains the following sections:
- Examples: Example VIs
- API: Top-level VIs
- SubVIs: Low-level VIs
Examples
API
SubVIs
API
Remove an element from the queue.
| Terminal | Description | Default |
|---|---|---|
| Queue in | String queue reference | |
| Timeout Message | Message returned if a timeout occurs. | "" |
| Timeout in ms | Milliseconds to wait before timing out | -1=Never |
| Message Type | Malleable type for Message | "" |
| Queue out | String queue reference out | |
| Message | Message text before comma: <msg>,<data> |
|
| Data | Remaining data after the comma: <msg>,<data> |
|
| Timed Out? | Returns True if no message is returned after Timeout in ms | |
| Element | Raw queue element returned |
| Malleable Controls | Supported Types |
|---|---|
| Timeout Message | String, Enum |
| Message Type | String, Enum |
| Message | String, Enum |
Add a message to the queue.
| Method | Description |
|---|---|
| Back | Enqueue to the back (last out) |
| Front | Enqueue to the front (first out) |
| Lossy | Force Enqueue to the back, drop front message if full |
| Absent | Enqueue to the back only if the message does not exist on the queue, otherwise do not enqueue |
Add a message to the queue. This malleable VI accepts multiple queues and message data types.
| Method | Description |
|---|---|
| Back | Enqueue to the back (last out) |
| Front | Enqueue to the front (first out) |
| Lossy | Force Enqueue to the back, drop front message if full |
| Absent | Enqueue to the back only if the message does not exist on the queue, otherwise do not enqueue |
Remove all elements in the queue. Returns the <msg>,<data> parts.
List all queue names and references.
Use the Obtain.vi to register the named queues.
Obtains a string queue reference. If Queue Name is defined, this caches the queue reference. Named queues return the same queue reference. Unnamed queues are not cached.
See List.vi to get a list of queues in memory.
Previews the next element in the queue. This malleable VI accepts a string or enum message data type.
Force release a queue reference and remove the named queue from the cache if exists. Obtaining named queues do not need to be released. The same reference is returned each time.
Warning: Releasing a queue always force destroys the queue reference.
Returns the status of a queue. If Return Elements? is True, this returns the <msg>,<data> element parts.
Wait for a named queue to be created. Rather than assuming a queue will be created, this waits for the child thread to create the queue. In multi-threaded applications, sub-threads may not be created at Run-Time, this ensures the thread that owns the queue reference is responsible for creating and destroying the queue reference. Specify the ms Timeout to limit the time to wait for the Queue Name to be obtained.
SubVIs
Named queue map used to maintain queue references in memory.
Return a queue by Queue Name.
Use this library's Obtain.vi to cache named queues.
Return the queue name given the Queue reference.
Use this library's Obtain.vi to cache named queues.