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ctThrdQueueRead
Read a queue message.
Short Name
ctThrdQueueRead()
Type
Threading function
Declaration
NINT ctThrdQueueRead(NINT qid, pVOID buffer, NINT buflen, LONG timeout)
Description
Read a queue message into buffer with maximum length buflen. If buffer is NULL and/or buflen is smaller than the actual message, the message is still removed from the queue, and as much as possible is placed into the buffer.
Return
In the case of a NULL or an insufficient buffer, ctThrdQueueRead() returns TQUE_ERR (638). If no message is available to be read within the interval specified in milliseconds by the timeout parameter, ctThrdQueueRead() returns NTIM_ERR (156). If more than one thread is reading the queue with an intermediate timeout parameter, i.e., greater than ctNOWAIT and less than ctWAITFOREVER, the length of time before a NTIM_ERR is returned is not accurate and such usage should not be attempted.
Value |
Symbolic Constant |
Explanation |
|---|---|---|
0 |
NO_ERROR |
Successful function. |
90 |
NQUE_ERR |
Invalid qid. |
156 |
NTIM_ERR |
block in use by another thread. Timeout error. |
514 |
CQUE_ERR |
Queue could not be closed. |
636 |
TSYF_ERR |
block get failed. |
638 |
TQUE_ERR |
Queue message truncated to fit. |
See FairCom DB Error Codes for a complete listing of valid FairCom DB error values.
Example
See ctmtap.c for ctThrdQueueRead() examples.
Limitations
Can only be used with a ctThrd library.
See also
ctThrdQueueClose, ctThrdQueueCount, ctThrdLIFOWrite, ctThrdQueueMlen, ctThrdQueueOpen, ctThrdQueueWrite
