private int preReadProcess(int allowed) {
if (allowed < 1) {
Debug.out("allowed < 1");
}
decode_array[0] =
payload_buffer == null
? null
: payload_buffer.getBuffer(
SS); // ensure the decode array has the latest payload pointer
int bytes_available = 0;
boolean shrink_remaining_buffers = false;
int start_buff = reading_length_mode ? 1 : 0;
boolean marked = false;
for (int i = start_buff; i < 2; i++) { // set buffer limits according to bytes allowed
ByteBuffer bb = decode_array[i];
if (bb == null) {
Debug.out("preReadProcess:: bb[" + i + "] == null, decoder destroyed=" + destroyed);
throw (new RuntimeException("decoder destroyed"));
}
if (shrink_remaining_buffers) {
bb.limit(0); // ensure no read into this next buffer is possible
} else {
int remaining = bb.remaining();
if (remaining < 1) continue; // skip full buffer
if (!marked) {
pre_read_start_buffer = i;
pre_read_start_position = bb.position();
marked = true;
}
if (remaining > allowed) { // read only part of this buffer
bb.limit(bb.position() + allowed); // limit current buffer
bytes_available += bb.remaining();
shrink_remaining_buffers = true; // shrink any tail buffers
} else { // full buffer is allowed to be read
bytes_available += remaining;
allowed -= remaining; // count this buffer toward allowed and move on to the next
}
}
}
return bytes_available;
}
public int performStreamDecode(Transport transport, int max_bytes) throws IOException {
try {
protocol_bytes_last_read = 0;
data_bytes_last_read = 0;
int bytes_remaining = max_bytes;
while (bytes_remaining > 0) {
if (destroyed) {
// destruction currently isn't thread safe so one thread can destroy the decoder (e.g.
// when closing a connection)
// while the read-controller is still actively processing the us
// throw( new IOException( "BTMessageDecoder already destroyed" ));
break;
}
if (is_paused) {
break;
}
int bytes_possible = preReadProcess(bytes_remaining);
if (bytes_possible < 1) {
Debug.out("ERROR BT: bytes_possible < 1");
break;
}
if (reading_length_mode) {
transport.read(decode_array, 1, 1); // only read into length buffer
} else {
transport.read(
decode_array, 0, 2); // read into payload buffer, and possibly next message length
}
int bytes_read = postReadProcess();
bytes_remaining -= bytes_read;
if (bytes_read < bytes_possible) {
break;
}
if (reading_length_mode && last_received_was_keepalive) {
// hack to stop a 0-byte-read after receiving a keep-alive message
// otherwise we won't realize there's nothing left on the line until trying to read again
last_received_was_keepalive = false;
break;
}
}
return max_bytes - bytes_remaining;
} catch (NullPointerException e) {
// due to lack of synchronization here the buffers can be nullified by a concurrent 'destroy'
// turn this into something less scarey
throw (new IOException("Decoder has most likely been destroyed"));
}
}
public ByteBuffer destroy() {
if (destroyed) {
Debug.out("Trying to redestroy message decoder, stack trace follows: " + this);
Debug.outStackTrace();
}
is_paused = true;
destroyed = true;
// there's a concurrency issue with the decoder whereby it can be destroyed while will being
// messed with. Don't
// have the energy to look into it properly atm so just try to ensure that it doesn't bork too
// badly (parg: 29/04/2012)
// only occasional but does have potential to generate direct buffer mem leak ;(
int lbuff_read = 0;
int pbuff_read = 0;
length_buffer.limit(SS, 4);
DirectByteBuffer plb = payload_buffer;
if (reading_length_mode) {
lbuff_read = length_buffer.position(SS);
} else { // reading payload
length_buffer.position(SS, 4);
lbuff_read = 4;
pbuff_read = plb == null ? 0 : plb.position(SS);
}
ByteBuffer unused = ByteBuffer.allocate(lbuff_read + pbuff_read); // TODO convert to direct?
length_buffer.flip(SS);
unused.put(length_buffer.getBuffer(SS));
try {
if (plb != null) {
plb.flip(SS);
unused.put(
plb.getBuffer(
SS)); // Got a buffer overflow exception here in the past - related to PEX?
}
} catch (RuntimeException e) {
Debug.out("hit known threading issue");
}
unused.flip();
length_buffer.returnToPool();
if (plb != null) {
plb.returnToPool();
payload_buffer = null;
}
try {
for (int i = 0; i < messages_last_read.size(); i++) {
Message msg = (Message) messages_last_read.get(i);
msg.destroy();
}
} catch (RuntimeException e) {
// happens if messages modified by alt thread...
Debug.out("hit known threading issue");
}
messages_last_read.clear();
return unused;
}