/** Find the next empty write chunk, sets self->writerChunk to it and returns * it.
*
* We only use the next one if it is empty. If not, we essentially just filled
* up the last chunk and wrapped around to the socket reader. In that case, we
* either create a new chunk if the overall buffer can still grow, or we drop
* the data from the current one.
*
* \warning A lock on the current writer chunk should be held prior to calling
* this function. It will be released, and the returned writerChunk will be
* similarly locked.
*
* \param self BufferedWriter pointer
* \param current locked BufferChunk to use or from which to find the next
* \return a locked BufferChunk in which data can be stored
*/
BufferChunk*
getNextWriteChunk(BufferedWriter* self, BufferChunk* current) {
int nlost;
BufferChunk* nextBuffer;
assert(current != NULL);
nextBuffer = current->next;
oml_unlock(¤t->lock, __FUNCTION__);
assert(nextBuffer != NULL);
oml_lock(&self->lock, __FUNCTION__);
if (nextBuffer == self->nextReaderChunk) {
if (self->unallocatedBuffers > 0) {
/* The next buffer is the next to be read, but we can allocate more,
* allocate a new buffer, insert it after the current writer, and use it */
nextBuffer = createBufferChunk(self);
assert(nextBuffer); /** \todo Use existing buffer if allocation fails */
oml_unlock(&self->lock, __FUNCTION__);
oml_lock(¤t->lock, __FUNCTION__);
nextBuffer->next = current->next;
current->next = nextBuffer; /* we have a lock on this one */
oml_unlock(¤t->lock, __FUNCTION__);
oml_lock(&self->lock, __FUNCTION__);
} else {
/* The next buffer is the next to be read, and we cannot allocate more,
* use it, dropping unread data, and advance the read pointer */
self->nextReaderChunk = nextBuffer->next;
}
}
self->writerChunk = nextBuffer;
nlost = bw_msgcount_reset(self);
self->nlost += nlost;
oml_unlock(&self->lock, __FUNCTION__);
oml_lock(&nextBuffer->lock, __FUNCTION__);
if (nlost) {
logwarn("%s: Dropping %d samples (%dB)\n", self->outStream->dest, nlost, mbuf_fill(nextBuffer->mbuf));
}
mbuf_clear2(nextBuffer->mbuf, 0);
// Now we just need to copy the message from current to self->writerChunk
int msgSize = mbuf_message_length(current->mbuf);
if (msgSize > 0) {
mbuf_write(nextBuffer->mbuf, mbuf_message(current->mbuf), msgSize);
mbuf_reset_write(current->mbuf);
}
return nextBuffer;
}
/**
* \brief Return and unlock MBuffer
*/
void
bw_unlock_buf(BufferedWriterHdl instance)
{
BufferedWriter* self = (BufferedWriter*)instance;
pthread_cond_signal(&self->semaphore); /* assume we locked for a reason */
oml_unlock(&self->lock, "bw_unlock_buf");
}
/** Return and unlock MBuffer
* \param instance BufferedWriter handle for which a buffer was previously obtained through bw_get_write_buf
*
* \see bw_get_write_buf
*/
void
bw_release_write_buf(BufferedWriter* instance)
{
BufferedWriter* self = (BufferedWriter*)instance;
pthread_cond_signal(&self->semaphore); /* assume we locked for a reason */
oml_unlock(&self->writerChunk->lock, __FUNCTION__);
}
/** Close an output stream and destroy the objects.
*
* \param instance handle (i.e., pointer) to a BufferedWriter
*/
void
bw_close(BufferedWriter* instance)
{
int *retval;
BufferedWriter *self = (BufferedWriter*)instance;
if(!self) { return; }
if (oml_lock (&self->lock, __FUNCTION__)) { return; }
self->active = 0;
loginfo ("%s: Waiting for buffered queue thread to drain...\n", self->outStream->dest);
pthread_cond_signal (&self->semaphore);
oml_unlock (&self->lock, __FUNCTION__);
if(pthread_join (self->readerThread, (void**)&retval)) {
logwarn ("%s: Cannot join buffered queue reader thread: %s\n",
self->outStream->dest, strerror(errno));
} else {
if (1 == *retval) {
logdebug ("%s: Buffered queue fully drained\n", self->outStream->dest);
} else {
logerror ("%s: Buffered queue did not fully drain\n",
self->outStream->dest, *retval);
}
}
self->outStream->close(self->outStream);
destroyBufferChain(self);
oml_free(self);
}
/**
* \fn static void* threadStart(void* handle)
* \brief start the filter thread
* \param handle the stream to use the filters on
*/
static void*
threadStart(void* handle)
{
BufferedWriter* self = (BufferedWriter*)handle;
BufferChain* chain = self->firstChain;
while (self->active) {
oml_lock(&self->lock, "bufferedWriter");
pthread_cond_wait(&self->semaphore, &self->lock);
// Process all chains which have data in them
while(1) {
if (mbuf_message(chain->mbuf) > mbuf_rdptr(chain->mbuf)) {
// got something to read from this chain
while (!processChain(self, chain));
}
// stop if we caught up to the writer
if (chain == self->writerChain) break;
chain = chain->next;
}
oml_unlock(&self->lock, "bufferedWriter");
}
return NULL;
}
/**
* \fn bw_push(BufferedWriterHdl* buffSocket, void* chunk, long chunkSize)
* \brief Add a chunk to the end of the queue.
* \param instance BufferedWriter handle
* \param chunk Pointer to chunk to add
* \param chunkSize size of chunk
* \return 1 if success, 0 otherwise
*/
int
bw_push(
BufferedWriterHdl instance,
uint8_t* chunk,
size_t size
) {
BufferedWriter* self = (BufferedWriter*)instance;
if (oml_lock(&self->lock, "bw_push")) return 0;
if (!self->active) return 0;
BufferChain* chain = self->writerChain;
if (chain == NULL) return 0;
if (chain->mbuf->wr_remaining < size) {
chain = self->writerChain = getNextWriteChain(self, chain);
}
if (mbuf_write(chain->mbuf, chunk, size) < 0)
return 0;
pthread_cond_signal(&self->semaphore);
// oml_unlock(&chain->lock, "bw_push");
oml_unlock(&self->lock, "bw_push");
return 1;
}
/** Close an output stream and destroy the objects.
*
* \param instance handle (i.e., pointer) to a BufferedWriter
*/
void bw_close(BufferedWriterHdl instance) {
BufferedWriter *next, *self = (BufferedWriter*)instance;
if(!self)
return;
if (oml_lock (&self->lock, "bw_close")) return;
self->active = 0;
loginfo ("Waiting for buffered queue reader thread to drain...\n");
pthread_cond_signal (&self->semaphore);
oml_unlock (&self->lock, "bw_close");
// pthread_cond_destroy(&self->semaphore, NULL);
switch (pthread_join (self->readerThread, NULL)) {
case 0:
loginfo ("Buffered queue reader thread finished OK...\n");
break;
case EINVAL:
logerror ("Buffered queue reader thread is not joinable\n");
break;
case EDEADLK:
logerror ("Buffered queue reader thread shutdown deadlock, or self-join\n");
break;
case ESRCH:
logerror ("Buffered queue reader thread shutdown failed: could not find the thread\n");
break;
default:
logerror ("Buffered queue reader thread shutdown failed with an unknown error\n");
break;
}
destroyBufferChain(self);
xfree(self);
}
/** Add some data to the end of the header buffer.
*
* \warning This function tries to acquire the lock on the header data, and
* releases it when done.
*
* \param instance BufferedWriter handle
* \param data Pointer to data to add
* \param size size of data
* \return 1 if success, 0 otherwise
*
* \see _bw_push_meta
*/
int
bw_push_meta(BufferedWriter* instance, uint8_t* data, size_t size)
{
int result = 0;
BufferedWriter* self = (BufferedWriter*)instance;
if (oml_lock(&self->meta_lock, __FUNCTION__) == 0) {
result = _bw_push_meta(instance, data, size);
oml_unlock(&self->meta_lock, __FUNCTION__);
}
return result;
}
/** Writing thread.
*
* \param handle the stream to use the filters on
* \return 1 if all the buffer chain has been processed, <1 otherwise
*/
static void*
bufferedWriterThread(void* handle)
{
int allsent = 1;
BufferedWriter* self = (BufferedWriter*)handle;
BufferChunk* chunk = self->firstChunk;
while (self->active) {
oml_lock(&self->lock, __FUNCTION__);
pthread_cond_wait(&self->semaphore, &self->lock);
// Process all chunks which have data in them
do {
oml_unlock(&self->lock, __FUNCTION__);
allsent = processChunk(self, chunk);
oml_lock(&self->lock, __FUNCTION__);
/* Stop if we caught up to the writer... */
if (chunk == self->writerChunk) { break; }
/* ...otherwise, move on to the next chunk */
if (allsent>0) {
chunk = getNextReadChunk(self);
}
} while(allsent > 0);
oml_unlock(&self->lock, __FUNCTION__);
}
/* Drain this writer before terminating */
/* XXX: “Backing-off for ...” messages might confuse the user as
* we don't actually wait after a failure when draining at the end */
while ((allsent=processChunk(self, chunk))>=-1) {
if(allsent>0) {
if (chunk == self->writerChunk) { break; };
oml_lock(&self->lock, __FUNCTION__);
chunk = getNextReadChunk(self);
oml_unlock(&self->lock, __FUNCTION__);
}
};
self->retval = allsent;
pthread_exit(&(self->retval));
}
/**
* \fn bw_push_meta(BufferedWriterHdl* buffSocket, void* chunk, long chunkSize)
* \brief Add a chunk to the end of the meta description.
*
* \param instance BufferedWriter handle
* \param chunk Pointer to chunk to add
* \param chunkSize size of chunk
* \return 1 if success, 0 otherwise
*/
int
bw_push_meta(
BufferedWriterHdl instance,
uint8_t* chunk,
size_t size
) {
BufferedWriter* self = (BufferedWriter*)instance;
int result = 0;
if (oml_lock(&self->lock, "bw_push")) return 0;
if (!self->active) return 0;
if (mbuf_write(self->meta_buf, chunk, size) > 0) {
result = 1;
pthread_cond_signal(&self->semaphore);
}
oml_unlock(&self->lock, "bw_push_meta");
return result;
}
// return 1 if chain has been fully sent, 0 otherwise
int
processChain(
BufferedWriter* self,
BufferChain* chain
) {
uint8_t* buf = mbuf_rdptr(chain->mbuf);
size_t size = mbuf_message_offset(chain->mbuf) - mbuf_read_offset(chain->mbuf);
size_t sent = 0;
chain->reading = 1;
oml_unlock(&self->lock, "processChain"); /* don't keep lock while transmitting */
MBuffer* meta = self->meta_buf;
while (size > sent) {
long cnt = self->writeFunc(self->writeFuncHdl, (void*)(buf + sent), size - sent,
meta->rdptr, meta->fill);
if (cnt > 0) {
sent += cnt;
} else {
/* ERROR: Sleep a bit and try again */
/* To be on the safe side, we rewind to the beginning of the
* chain and try to resend everything - this is especially important
* if the underlying stream needs to reopen and resync.
*/
mbuf_reset_read(chain->mbuf);
size = mbuf_message_offset(chain->mbuf) - mbuf_read_offset(chain->mbuf);
sent = 0;
sleep(1);
}
}
// get lock back to see what happened while we were busy
oml_lock_persistent(self);
mbuf_read_skip(chain->mbuf, sent);
if (mbuf_write_offset(chain->mbuf) == mbuf_read_offset(chain->mbuf)) {
// seem to have sent everything so far, reset chain
// mbuf_clear2(chain->mbuf, 0);
mbuf_clear2(chain->mbuf, 1);
chain->reading = 0;
return 1;
}
return 0;
}
/**
* \brief Return an MBuffer with exclusive write access
* \return MBuffr instance if success, NULL otherwise
*/
MBuffer*
bw_get_write_buf(
BufferedWriterHdl instance,
int exclusive
) {
BufferedWriter* self = (BufferedWriter*)instance;
if (oml_lock(&self->lock, "bw_get_write_buf")) return 0;
if (!self->active) return 0;
BufferChain* chain = self->writerChain;
if (chain == NULL) return 0;
MBuffer* mbuf = chain->mbuf;
if (mbuf_write_offset(mbuf) >= chain->targetBufSize) {
chain = self->writerChain = getNextWriteChain(self, chain);
mbuf = chain->mbuf;
}
if (! exclusive) {
oml_unlock(&self->lock, "bw_get_write_buf");
}
return mbuf;
}
/** Send data contained in one chunk.
*
* \warning This function acquires the lock on the BufferedWriter for the time
* it takes to check the double-buffer.
*
* \warning This function acquires the lock on the chunk being processed for
* the time it takes to check it and swap the double buffer.
*
* \bug The meta buffer should also be protected.
*
* \param self BufferedWriter to process
* \param chunk link of the chunk to process
*
* \return 1 if chunk has been fully sent, 0 if not, -1 on continuing back-off, -2 otherwise
* \see oml_outs_write_f
*/
static int
processChunk(BufferedWriter* self, BufferChunk* chunk)
{
time_t now;
int ret = -2;
ssize_t cnt = 0;
MBuffer *read_buf = NULL;
assert(self);
assert(self->meta_buf);
assert(self->read_buf);
assert(chunk);
assert(chunk->mbuf);
oml_lock(&self->lock, __FUNCTION__);
if (mbuf_message(self->read_buf) > mbuf_rdptr(self->read_buf)) {
/* There is unread data in the double buffer */
read_buf = self->read_buf;
}
oml_unlock(&self->lock, __FUNCTION__);
oml_lock(&chunk->lock, __FUNCTION__);
if ((NULL == read_buf) && (mbuf_message(chunk->mbuf) >= mbuf_rdptr(chunk->mbuf))) {
/* There is unread data in the read buffer, swap MBuffers */
read_buf = chunk->mbuf;
chunk->mbuf = self->read_buf;
}
oml_unlock(&chunk->lock, __FUNCTION__);
oml_lock(&self->lock, __FUNCTION__);
self->read_buf = read_buf;
oml_unlock(&self->lock, __FUNCTION__);
if (NULL == read_buf) {
/* The current message is not after the read pointer,
* we must be on the writer chunk */
ret = 1;
goto processChunk_cleanup;
}
time(&now);
if (difftime(now, self->last_failure_time) < self->backoff) {
logdebug("%s: Still in back-off period (%ds)\n", self->outStream->dest, self->backoff);
ret = -1;
goto processChunk_cleanup;
}
while (mbuf_write_offset(read_buf) > mbuf_read_offset(read_buf)) {
oml_lock(&self->meta_lock, __FUNCTION__);
cnt = self->outStream->write(self->outStream,
mbuf_rdptr(read_buf), mbuf_message_offset(read_buf) - mbuf_read_offset(read_buf),
mbuf_rdptr(self->meta_buf), mbuf_fill(self->meta_buf));
oml_unlock(&self->meta_lock, __FUNCTION__);
if (cnt > 0) {
mbuf_read_skip(read_buf, cnt);
if (self->backoff) {
self->backoff = 0;
loginfo("%s: Connected\n", self->outStream->dest);
}
} else {
self->last_failure_time = now;
if (!self->backoff) {
self->backoff = 1;
} else if (self->backoff < UINT8_MAX) {
self->backoff *= 2;
}
logwarn("%s: Error sending, backing off for %ds\n", self->outStream->dest, self->backoff);
goto processChunk_cleanup;
}
}
ret = 1;
processChunk_cleanup:
return ret;
}
/** Unlock a measurement point mutex
* \param mp OmlMP to unlock
* \see mp_lock, oml_unlock
*/
void
mp_unlock(OmlMP* mp)
{
oml_unlock(mp->mutexP, mp->name);
}
