/** 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;
}
/** Finalise a marshalled message.
*
* Depending on the number of values packed, change the type of message, and
* write the actual size in the right location of the header, in network byte
* order.
*
* \param mbuf MBuffer where marshalled data is
* \return 1
* \see marshal_init, marshal_measurements, marshal_values
*/
int
marshal_finalize(MBuffer* mbuf)
{
uint8_t* buf = mbuf_message (mbuf);
OmlBinMsgType type = marshal_get_msgtype (mbuf);
size_t len = mbuf_message_length (mbuf);
if (len > UINT32_MAX) {
logwarn("Message length %d longer than maximum packet length (%d); "
"packet will be truncated\n",
len, UINT32_MAX);
len = UINT32_MAX;
}
if (type == OMB_DATA_P && len > UINT16_MAX) {
/*
* We assumed a short packet, but there is too much data, so we
* have to shift the whole buffer down by 2 bytes and convert to a
* long packet.
*/
uint8_t s[2] = {0};
/* Put some padding in the buffer to make sure it has room, and maintains its invariants */
mbuf_write (mbuf, s, sizeof (s));
memmove (&buf[PACKET_HEADER_SIZE+2], &buf[PACKET_HEADER_SIZE],
len - PACKET_HEADER_SIZE);
len += 2;
buf[2] = type = OMB_LDATA_P;
}
switch (type) {
case OMB_DATA_P:
len -= PACKET_HEADER_SIZE; // Data length minus header
uint16_t nlen16 = htons (len);
memcpy (&buf[3], &nlen16, sizeof (nlen16));
break;
case OMB_LDATA_P:
len -= PACKET_HEADER_SIZE + 2; // Data length minus header
uint32_t nlen32 = htonl (len); // pure data length
memcpy (&buf[3], &nlen32, sizeof (nlen32));
break;
}
return 1;
}
/** Function called after all items in a tuple have been sent
* \see oml_writer_row_end
*
* This releases the lock on the BufferedWriter.
*
* \see BufferedWriter, bw_unlock_buf, marshal_finalize
*/
static int
owb_row_end(OmlWriter* writer, OmlMStream* ms) {
(void)ms;
OmlBinWriter* self = (OmlBinWriter*)writer;
MBuffer* mbuf;
if ((mbuf = self->mbuf) == NULL) {
return 0; /* previous use of mbuf failed */
}
marshal_finalize(self->mbuf);
if (marshal_get_msgtype (self->mbuf) == OMB_LDATA_P) {
self->msgtype = OMB_LDATA_P; // Generate long packets from now on.
}
if (0 == ms->index) {
/* This is schema0, also push the data into the meta_buf
* to be replayed after a disconnection.
*
* At the moment, the oml_outs_write_f takes header information as a
* whole, but does not push more once it has sent the initial block. Its
* two last parameters are only used to resend the entirety of the headers
* when a disconnection does occur, nothing before.
*
* We therefore send the extra piece of data the normal way, but also
* record it, separately, in the meta_buf
*
* XXX: This logic should be in higher layer levels, but given the current
* implementation, with some of it already spread down into the
* OmlOutStream (oml_outs_write_f), this require a much bigger refactoring.
* It is also duplicated with the OmlTextWriter (see #1101).
*/
_bw_push_meta(self->bufferedWriter,
mbuf_message(self->mbuf), mbuf_message_length(self->mbuf));
}
mbuf_begin_write(mbuf);
self->mbuf = NULL;
bw_unlock_buf(self->bufferedWriter);
return 1;
}
// 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;
}
