my queue set seems to be ignoring the full queue.
xQueueSelectFromSet() always times out, but the queue is full and it can be read.
Here is a simplified example of my situation.
Did I misunderstood something and have false expectations, or is such behavior expected?
ISR:
if(xQueueIsQueueFullFromISR(queue)){
xQueueReceiveFromISR(queue, &dummy, &pxHigherPriorityTaskWoken);
}
xQueueSendFromISR(queue, event, &pxHigherPriorityTaskWoken);
task2:
xQueueSet = xQueueCreateSet(QUEUE_LENGTH + 1);
xQueueAddToSet(queue, xQueueSet);
xQueueAddToSet(semaphore, xQueueSet);
while(true){
xActivatedMember = xQueueSelectFromSet(xQueueSet, 100);
if(xActivatedMember == semaphore){
xSemaphoreTake(semaphore, 0);
break; // from the infinite loop
}else if(xActivatedMember == queue){
// read from queue
}else if(xActivatedMember == NULL){
// timed out but queue is full
uxQueueMessagesWaiting(queue); // returns QUEUE_LENGTH
xQueueReceive(queue, &event, 0); // reads without problem
} // xActivatedMember
} // infinite loop
Related
I have some coroutine handling code like this:
int coro_re_num = 0;
int coro_state = lua_resume( coro_lua, master_lua, narg, &coro_re_num);
if ( coro_state == LUA_OK)
{
// do something
}
else if ( coro_state == LUA_YIELD)
{
// do_something
}
else
{
const char* err = lua_tostring(coro_lua, -1);
log_error(err);
}
lua_pop(master_lua, coro_re_num);
When coroutine ends with OK or YIELD, it works properly. But when it ends with any error, the last lua_pop always fail, and I noticed the coro_re_num is relatively large (mostly more than 10) which causes stack underflow by lua_pop.
What does the coro_re_num means when the coroutine ends with error? How to handle it?
if we are using GCD approach for iteration , how to break/stop the loop once the condition matched?
queue = dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_HIGH, 0);
dispatch_apply(count, queue, ^(size_t i) {
printf("%u\n", i);
//doing thread safe(also heavy) operation here
if (condition) {
//exit the loop
}
});
It is not possible to cancel dispatch_apply as not all operations are completed sequentially but concurrently. The purpose of dispatch_apply is to parallelize a for-loop where all iterations are independent from other iterations.
However you can use a boolean which indicates that the condition was satisfied. All pending operations are cancelled immediately as they are invoked.
__block BOOL stop = NO;
queue = dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0)
dispatch_apply(count, queue, ^(size_t i) {
if (stop)
return;
//Do stuff
if (condition)
stop = YES;
});
In the following code
SendMessage() is the API called by the user to send a message over USB
UsbDataReceived() is the function called by another thread when data is received on the USB
Task() is the thread created in init() that reads from the queue filled by SendMessage() and calls the low level usb function to send a message
UsbConnected() is the function called by another thread when a USB device is connected.
I need to implement the following behaviour:
Once a message has been sent, no new messages can be sent up to when an answer for the last message has arrived
When UsbConnected() is called, all of the queues must be emptied and if the thread Task() is waiting on the queue AnswerQueue, it has to be unblocked so that it can go back to wait on the queue CommandQueue
An example of my best solution is listed below.
I had to post an EVENT_QUEUE_RESETTED message on both of the queues with a particular order.
Is it possible to achieve the same result in a less cumbersome way?
void UsbhOut(Message_t );
int UsbConnected;
QueueHandle_t MessageQueue;
typedef enum
{
EVENT_QUEUE_RESETTED,
EVENT_NEW_MESSAGE,
EVENT_NEW_ANSWER,
} Event_t;
typedef struct
{
Event_t Event;
uint8_t Data[32];
} CommandQueue_t;
typedef struct
{
Event_t Event;
uint8_t Data[32];
} AnswerQueue_t;
void init(void)
{
MessageQueue = xQueueCreate(sizeof(Message_t), 10);
AnswerQueue = xQueueCreate(sizeof(Message_t), 10);
xTaskCreate(Task, "", 200, NULL, 1, NULL);
}
void UsbConnected(void)
{
CommandEvent.Event = EVENT_QUEUE_RESETTED;
AnswerEvent.Event = EVENT_QUEUE_RESETTED;
UsbConnected = 1;
xQueueReset(MessageQueue);
xQueueReset(AnswerQueue);
/* The order here is fundmental */
xQueueSend(AnswerQueue, &AnswerEvent, 0);
xQueueSend(MessageQeueue, &CommandEvent, 0);
}
int SendMessage(uint8_t * Data)
{
CommandQueue_t CommandEvent;
CommandEvent.Event = EVENT_NEW_MESSAGE;
memcpy(&CommandEvent, Message, 32);
if(xQueueSend(MessageQueue, &CommandEvent, 0) == pdTRUE)
return 0;
else
return -1;
}
void UsbDataReceived(uint8_t * Data)
{
AnswerQueue_t AnswerEvent;
AnswerEvent.Event = EVENT_NEW_ANSWER;
memcpy(AnswerEvent.Data, Data, 32);
xQueueSend(AnswerQueue, &AnswerEvent,0);
}
void Task(void *pvParameters)
{
CommandQueue_t CommandEvent;
AnswerQueue_t AnswerEvent;
CommandCallback_t * Callback;
while(1)
{
xQueueReceive(UsbhStaticData.CommandSenderQueue, &CommandEvent, portMAX_DELAY);
if(CommandEvent.Event == CommandSenderQueueData_t::EVENT_QUEUE_RESETTED)
{
continue;
}
/* Low level Usb fucntion used to send Data */
UsbdSendData(Command.Data);
xQueueReceive(UsbhStaticData.AnswerReceivdQueue, &AnswerEvent, portMAX_DELAY);
if(AnswerEvent.Event == AnswerReceivedQueueData_t::EVENT_QUEUE_RESETTED)
{
continue;
}
else if(AnswerEvent.Event == AnswerReceivedQueueData_t::EVENT_ANSWER_RECEIVED)
{
ParseData(AnswerEvent.Data);
}
}
}
You could use Queue Sets
FreeRTOS Queue Set API
That way you could create a Queue Set containing a queue and a semaphore. Your task would block on the Queue Set. It would then get unblocked by either receiving a message from the queue or you incrementing the semaphore.
My pthread_detach calls fail with a "Bad file descriptor" error. The calls are in the destructor for my class and look like this -
if(pthread_detach(get_sensors) != 0)
printf("\ndetach on get_sensors failed with error %m", errno);
if(pthread_detach(get_real_velocity) != 0)
printf("\ndetach on get_real_velocity failed with error %m", errno);
I have only ever dealt with this error when using sockets. What could be causing this to happen in a pthread_detach call that I should look for? Or is it likely something in the thread callback that could be causing it? Just in case, the callbacks look like this -
void* Robot::get_real_velocity_thread(void* threadid) {
Robot* r = (Robot*)threadid;
r->get_real_velocity_thread_i();
}
inline void Robot::get_real_velocity_thread_i() {
while(1) {
usleep(14500);
sensor_packet temp = get_sensor_value(REQUESTED_VELOCITY);
real_velocity = temp.values[0];
if(temp.values[1] != -1)
real_velocity += temp.values[1];
} //end while
}
/*Callback for get sensors thread*/
void* Robot::get_sensors_thread(void* threadid) {
Robot* r = (Robot*)threadid;
r->get_sensors_thread_i();
} //END GETSENSORS_THREAD
inline void Robot::get_sensors_thread_i() {
while(1) {
usleep(14500);
if(sensorsstreaming) {
unsigned char receive;
int read = 0;
read = connection.PollComport(port, &receive, sizeof(unsigned char));
if((int)receive == 19) {
read = connection.PollComport(port, &receive, sizeof(unsigned char));
unsigned char rest[54];
read = connection.PollComport(port, rest, 54);
/* ***SET SENSOR VALUES*** */
//bump + wheel drop
sensor_values[0] = (int)rest[1];
sensor_values[1] = -1;
//wall
sensor_values[2] = (int)rest[2];
sensor_values[3] = -1;
...
...
lots more setting just like the two above
} //end if header == 19
} //end if sensors streaming
} //end while
} //END GET_SENSORS_THREAD_I
Thank you for any help.
The pthread_* functions return an error code; they do not set errno. (Well, they may of course, but not in any way that is documented.)
Your code should print the value returned by pthread_detach and print that.
Single Unix Spec documents two return values for this function: ESRCH (no thread by that ID was found) and EINVAL (the thread is not joinable).
Detaching threads in the destructor of an object seems silly. Firstly, if they are going to be detached eventually, why not just create them that way?
If there is any risk that the threads can use the object that is being destroyed, they need to be stopped, not detached. I.e. you somehow indicate to the threads that they should shut down, and then wait for them to reach some safe place after which they will not touch the object any more. pthread_join is useful for this.
Also, it is a little late to be doing that from the destructor. A destructor should only be run when the thread executing it is the only thread with a reference to that object. If threads are still using the object, then you're destroying it from under them.
I am new to IOCP and struggling with this for last few weeks.
I have pasted some core part of my code below related to IOCP.This may not be executed perfectly as I clipped some part to make it easy to understand.
I am struggling while receiving the data.As it comes to wsarecv in worket thread, wsarecv returns WSA_IO_PENDING error code so I call WSAGetOverlappedResult to check operation to be completed.
Twist comes here, rather it proceed and call my local function ProcessTelegramData after WSAGetOverlappedResult , same part of code(wsarecv called again) is executed again by another worker thread which try to call ProcessTelegramData and buffer value is invalid in it.
I am unable to understand
why another thread calling wsarecv again when WSAGetOverlappedResult is called and
why buffer value is getting invalidated?
unsigned LicTCPServer::WorkerThread(LPVOID lpParam)
{
//int nThreadNo = (int)lpParam;
LicTCPServer* pThis = reinterpret_cast<LicTCPServer*>(lpParam);
void *lpContext = NULL;
OVERLAPPED *pOverlapped = NULL;
CClientContext *pClientContext = NULL;
DWORD dwBytesTransfered = 0;
int nBytesRecv = 0;
int nBytesSent = 0;
DWORD dwBytes = 0, dwFlags = 0;
//Worker thread will be around to process requests, until a Shutdown event is not Signaled.
while (WAIT_OBJECT_0 != WaitForSingleObject(g_hShutdownEvent, 0))
{
BOOL bReturn = GetQueuedCompletionStatus(
g_hIOCompletionPort,
&dwBytesTransfered,
(LPDWORD)&lpContext,
&pOverlapped,
INFINITE);
if (NULL == lpContext)
{
//We are shutting down
break;
}
//Get the client context
pClientContext = (CClientContext *)lpContext;
if ((FALSE == bReturn) /*|| ((TRUE == bReturn) && (0 == dwBytesTransfered))*/)
{
//Client connection gone, remove it.
pThis->RemoveFromClientListAndFreeMemory(pClientContext);
continue;
}
WSABUF *p_wbuf = pClientContext->GetWSABUFPtr();
OVERLAPPED *p_ol = pClientContext->GetOVERLAPPEDPtr();
//printf("reached %d\n",pClientContext->GetOpCode());
printf("Get Queued received\n");
switch (pClientContext->GetOpCode())
{
case OP_READ:
{
//Once the data is successfully received, we will print it.
//pClientContext->SetOpCode(OP_WRITE);
pClientContext->ResetWSABUF();
dwFlags = 0;
//int a = recv(pClientContext->GetSocket(), p_wbuf->buf, p_wbuf->len, 0);
//Get the data.
if(WSARecv(pClientContext->GetSocket(), p_wbuf, 1, &dwBytes, &dwFlags, p_ol, NULL) == SOCKET_ERROR)
{
if (WSAGetLastError() != WSA_IO_PENDING)
{
printf("Error occured at WSARecv()\n");
return 0;
}
}
DWORD byteTr = 0;
WSAGetOverlappedResult(pClientContext->GetSocket(),p_ol,&byteTr,TRUE,&dwFlags);
if( byteTr > 0 )
{
//doing some operatin on data received
printf("Process tele called\n");
g_pLicServFunc->ProcessTelegramData(pClientContext->GetSocket(), p_wbuf->buf, byteTr);
}
if ((SOCKET_ERROR == nBytesRecv) && (WSA_IO_PENDING != WSAGetLastError()))
{
//WriteToConsole("\nThread %d: Error occurred while executing WSARecv().", nThreadNo);
//Let's not work with this client
//TBC
//RemoveFromClientListAndFreeMemory(pClientContext);
}
}
break;
case OP_WRITE:
char szBuffer[MAX_BUFFER_LEN];
//Send the message back to the client.
pClientContext->SetOpCode(OP_READ);
pClientContext->SetTotalBytes(dwBytesTransfered);
pClientContext->SetSentBytes(0);
//p_wbuf->len = dwBytesTransfered;
dwFlags = 0;
DWORD temp;
//Overlapped send
printf("reached Going to send\n");
//send(pClientContext->GetSocket(), p_wbuf->buf,p_wbuf->len, 0);
nBytesSent = WSASend(pClientContext->GetSocket(), p_wbuf, 1,
&temp, dwFlags, p_ol, NULL);
if ((SOCKET_ERROR == nBytesSent) && (WSA_IO_PENDING != WSAGetLastError()))
{
//WriteToConsole("\nThread %d: Error occurred while executing WSASend().", nThreadNo);
//Let's not work with this client
//TBC
//RemoveFromClientListAndFreeMemory(pClientContext);
}
break;
default:
printf("reached to default\n");
//We should never be reaching here, under normal circumstances.
break;
} // switch
} // while
return 0;
}
I had a similar issue with WSARecv where it always queued to the io completion queue, even if it succeeded immediately. I had to ignore a return value indicating success and instead handle the queued result that I got from GetQueuedCompletionStatus.