/*
* QBufPipe_Finish
*
* Blocks until the reader thread handles all commands
* or terminates with an error.
*/
void QBufPipe_Finish( qbufPipe_t *pipe ) {
while( Sys_Atomic_CAS( &pipe->cmdbuf_len, 0, 0, pipe->cmdbuf_mutex ) == false && !pipe->terminated ) {
QMutex_Lock( pipe->nonempty_mutex );
QBufPipe_Wake( pipe );
QMutex_Unlock( pipe->nonempty_mutex );
QThread_Yield();
}
}
/*
* QBufPipe_WriteCmd
*
* Add new command to buffer. Never allow the distance between the reader
* and the writer to grow beyond the size of the buffer.
*
* Note that there are race conditions here but in the worst case we're going
* to erroneously drop cmd's instead of stepping on the reader's toes.
*/
void QBufPipe_WriteCmd( qbufPipe_t *pipe, const void *cmd, unsigned cmd_size )
{
void *buf;
unsigned write_remains;
bool was_empty;
if( !pipe ) {
return;
}
if( pipe->terminated ) {
return;
}
assert( pipe->bufSize >= pipe->write_pos );
if( pipe->bufSize < pipe->write_pos ) {
pipe->write_pos = 0;
}
was_empty = Sys_Atomic_CAS( &pipe->cmdbuf_len, 0, 0, pipe->cmdbuf_mutex ) == true;
write_remains = pipe->bufSize - pipe->write_pos;
if( sizeof( int ) > write_remains ) {
while( pipe->cmdbuf_len + cmd_size + write_remains > pipe->bufSize ) {
if( pipe->blockWrite ) {
QThread_Yield();
continue;
}
return;
}
// not enough space to enpipe even the reset cmd, rewind
QBufPipe_BufLenAdd( pipe, write_remains ); // atomic
pipe->write_pos = 0;
} else if( cmd_size > write_remains ) {
int *cmd;
while( pipe->cmdbuf_len + sizeof( int ) + cmd_size + write_remains > pipe->bufSize ) {
if( pipe->blockWrite ) {
QThread_Yield();
continue;
}
return;
}
// explicit pointer reset cmd
cmd = QBufPipe_AllocCmd( pipe, sizeof( int ) );
*cmd = -1;
QBufPipe_BufLenAdd( pipe, sizeof( *cmd ) + write_remains ); // atomic
pipe->write_pos = 0;
}
else
{
while( pipe->cmdbuf_len + cmd_size > pipe->bufSize ) {
if( pipe->blockWrite ) {
QThread_Yield();
continue;
}
return;
}
}
buf = QBufPipe_AllocCmd( pipe, cmd_size );
memcpy( buf, cmd, cmd_size );
QBufPipe_BufLenAdd( pipe, cmd_size ); // atomic
// wake the other thread waiting for signal
if( was_empty ) {
QMutex_Lock( pipe->nonempty_mutex );
QBufPipe_Wake( pipe );
QMutex_Unlock( pipe->nonempty_mutex );
}
}
