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fixes to irc/socket.go
* fix a race condition: a call to `Write` does not spawn a writer goroutine if the trylock is held, so `BlockingWrite` must check for fresh data after releasing the trylock * streamline some close/finalize logic
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a0bf548fc5
commit
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@ -134,6 +134,7 @@ func (socket *Socket) Write(data []byte) (err error) {
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prospectiveLen := socket.totalLength + len(data)
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prospectiveLen := socket.totalLength + len(data)
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if prospectiveLen > socket.maxSendQBytes {
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if prospectiveLen > socket.maxSendQBytes {
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socket.sendQExceeded = true
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socket.sendQExceeded = true
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socket.closed = true
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err = errSendQExceeded
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err = errSendQExceeded
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} else {
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} else {
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socket.buffers = append(socket.buffers, data)
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socket.buffers = append(socket.buffers, data)
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@ -161,6 +162,13 @@ func (socket *Socket) BlockingWrite(data []byte) (err error) {
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return
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return
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}
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}
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// after releasing the semaphore, we must check for fresh data, same as `send`
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defer func() {
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if socket.readyToWrite() {
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socket.wakeWriter()
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}
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}()
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// blocking acquire of the trylock
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// blocking acquire of the trylock
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socket.writerSemaphore.Acquire()
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socket.writerSemaphore.Acquire()
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defer socket.writerSemaphore.Release()
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defer socket.writerSemaphore.Release()
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@ -206,7 +214,7 @@ func (socket *Socket) readyToWrite() bool {
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socket.Lock()
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socket.Lock()
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defer socket.Unlock()
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defer socket.Unlock()
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// on the first time observing socket.closed, we still have to write socket.finalData
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// on the first time observing socket.closed, we still have to write socket.finalData
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return !socket.finalized && (socket.totalLength > 0 || socket.closed || socket.sendQExceeded)
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return !socket.finalized && (socket.totalLength > 0 || socket.closed)
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}
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}
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// send actually writes messages to socket.Conn; it may block
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// send actually writes messages to socket.Conn; it may block
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@ -238,19 +246,20 @@ func (socket *Socket) performWrite() (closed bool) {
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buffers := socket.buffers
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buffers := socket.buffers
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socket.buffers = nil
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socket.buffers = nil
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socket.totalLength = 0
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socket.totalLength = 0
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closed = socket.closed
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socket.Unlock()
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socket.Unlock()
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// on Linux, the runtime will optimize this into a single writev(2) call:
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var err error
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_, err := (*net.Buffers)(&buffers).WriteTo(socket.conn)
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if !closed && len(buffers) > 0 {
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// on Linux, the runtime will optimize this into a single writev(2) call:
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_, err = (*net.Buffers)(&buffers).WriteTo(socket.conn)
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}
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socket.Lock()
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closed = closed || err != nil
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shouldClose := (err != nil) || socket.closed || socket.sendQExceeded
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if closed {
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socket.Unlock()
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if shouldClose {
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socket.finalize()
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socket.finalize()
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}
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}
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return shouldClose
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return
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}
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}
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// mark closed and send final data. you must be holding the semaphore to call this:
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// mark closed and send final data. you must be holding the semaphore to call this:
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@ -258,12 +267,18 @@ func (socket *Socket) finalize() {
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// mark the socket closed (if someone hasn't already), then write error lines
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// mark the socket closed (if someone hasn't already), then write error lines
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socket.Lock()
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socket.Lock()
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socket.closed = true
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socket.closed = true
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finalized := socket.finalized
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socket.finalized = true
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socket.finalized = true
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finalData := socket.finalData
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finalData := socket.finalData
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if socket.sendQExceeded {
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if socket.sendQExceeded {
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finalData = "\r\nERROR :SendQ Exceeded\r\n"
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finalData = "\r\nERROR :SendQ Exceeded\r\n"
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}
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}
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socket.Unlock()
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socket.Unlock()
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if finalized {
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return
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}
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if finalData != "" {
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if finalData != "" {
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socket.conn.Write([]byte(finalData))
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socket.conn.Write([]byte(finalData))
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}
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}
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