/** 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;
}
// 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;
}
// This function finds the next empty write chain, sets +self->writeChain+ to
// it and returns.
//
// We only use the next one if it is empty. If not, we
// essentially just filled up the last chain and wrapped
// around to the socket reader. In that case, we either create a new chain
// if the overall buffer can still grow, or we drop the data from the current one.
//
// This assumes that the current thread holds the +self->lock+ and the lock on
// the +self->writeChain+.
//
BufferChain*
getNextWriteChain(
BufferedWriter* self,
BufferChain* current
) {
assert(current != NULL);
BufferChain* nextBuffer = current->next;
assert(nextBuffer != NULL);
BufferChain* resChain = NULL;
if (mbuf_remaining(nextBuffer->mbuf) == 0) {
// It's empty, we can use it
mbuf_clear2(nextBuffer->mbuf, 0);
resChain = nextBuffer;
} else if (self->chainsAvailable > 0) {
// insert new chain between current and next one.
BufferChain* newBuffer = createBufferChain(self);
newBuffer->next = nextBuffer;
current->next = newBuffer;
resChain = newBuffer;
} else {
// Filled up buffer, time to drop data and reuse current buffer
// Current buffer holds most recent added data (we drop from the queue's tail
//assert(current->reading == 0);
assert(current->reading == 0);
o_log (O_LOG_WARN, "Dropping %d bytes of measurement data\n", mbuf_fill(current->mbuf));
mbuf_repack_message2(current->mbuf);
return current;
}
// Now we just need to copy the +message+ from +current+ to +resChain+
int msgSize = mbuf_message_length(current->mbuf);
if (msgSize > 0) {
mbuf_write(resChain->mbuf, mbuf_message(current->mbuf), msgSize);
mbuf_reset_write(current->mbuf);
}
return resChain;
}
