backup/directplay-lite
1
0
Fork 0
mirror of https://github.com/solemnwarning/directplay-lite synced 2024-12-30 16:45:37 +01:00
Code Issues Projects Releases Activity

Avoid spinning the workers whenever a peer is connected.

Browse Source 
Calling WSAEventSelect() causes the event to become signalled
even if there is nothing new, probably due to the socket being
writable.

Due to this, io_peer_recv() signals the event object whenever
claiming recv_busy just to check for pending data, and again
when releasing it, which leads to another worker immediately
waking up and claiming it to check for new messages, starting
the cycle again.

Only claim recv_busy and mask FD_RECV events if some data is
actually read from the socket.
This commit is contained in:
Daniel Collins 2018-10-24 00:57:09 +01:00
parent 14c78e506b
commit 44423f4596
1 changed files with 36 additions and 38 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

74
src/DirectPlay8Peer.cpp
View File

@ -2514,32 +2514,39 @@ void DirectPlay8Peer::io_peer_recv(std::unique_lock<std::mutex> &l, unsigned int
while((peer = get_peer_by_peer_id(peer_id)) != NULL)
{
if(!rb_claimed)
if(!rb_claimed && peer->recv_busy)
{
if(peer->recv_busy)
{
/* Another thread is already processing data from this socket.
*
* Only one thread at a time is allowed to handle reads, even when the
* other thread is in the application callback, so that the order of
* messages is preserved.
*/
return;
}
else{
/* No other thread is processing data from this peer, we shall
* claim the throne and temporarily disable FD_READ events from it
* to avoid other workers spinning against the recv_busy lock.
*/
peer->recv_busy = true;
rb_claimed = true;
peer->disable_events(FD_READ | FD_CLOSE);
}
/* Another thread is already processing data from this socket.
*
* Only one thread at a time is allowed to handle reads, even when the
* other thread is in the application callback, so that the order of
* messages is preserved.
*/
return;
}
int r = recv(peer->sock, (char*)(peer->recv_buf) + peer->recv_buf_cur, sizeof(peer->recv_buf) - peer->recv_buf_cur, 0);
DWORD err = WSAGetLastError();
if(r < 0 && err == WSAEWOULDBLOCK)
{
/* Nothing to read. */
break;
}
if(!rb_claimed)
{
/* No other thread is processing data from this peer, we shall
* claim the throne and temporarily disable FD_READ events from it
* to avoid other workers spinning against the recv_busy lock.
*/
peer->recv_busy = true;
rb_claimed = true;
peer->disable_events(FD_READ | FD_CLOSE);
}
if(r == 0)
{
/* When the remote end initiates a graceful close, it will no longer
@ -2551,22 +2558,13 @@ void DirectPlay8Peer::io_peer_recv(std::unique_lock<std::mutex> &l, unsigned int
}
else if(r < 0)
{
DWORD err = WSAGetLastError();
/* Read error. */
if(err == WSAEWOULDBLOCK)
{
/* Nothing to read */
break;
}
else{
/* Read error. */
log_printf("Read error on peer %u: %s", peer_id, win_strerror(err).c_str());
log_printf("Closing connection");
peer_destroy(l, peer_id, DPNERR_CONNECTIONLOST, DPNDESTROYPLAYERREASON_CONNECTIONLOST);
return;
}
log_printf("Read error on peer %u: %s", peer_id, win_strerror(err).c_str());
log_printf("Closing connection");
peer_destroy(l, peer_id, DPNERR_CONNECTIONLOST, DPNDESTROYPLAYERREASON_CONNECTIONLOST);
return;
}
if(peer->state == Peer::PS_CLOSING)
@ -2715,7 +2713,7 @@ void DirectPlay8Peer::io_peer_recv(std::unique_lock<std::mutex> &l, unsigned int
}
}
if(peer != NULL)
if(peer != NULL && rb_claimed)
{
peer->enable_events(FD_READ | FD_CLOSE);
peer->recv_busy = false;