server: Fix deadlock if StopBgp is called when conn queue is full #2771
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Fixes a deadlock condition that can happen if StopBgp is called when the pending connection queue is full. During teardown, StopBgp calls a mgmtOp on the server goroutine which attempts to stop the goroutine accepting inbound connections, and waits for it to finish before continuing. This connection goroutine can block if the connection queue is full, which is read by the same goroutine that processes all mgmtOps. This means that if the queue is full and the goroutine is currently blocked, then calling StopBgp will lead to a complete deadlock, as the connection goroutine will never close as it is trying to send to the queue, but the queue will not be read as the server goroutine is currently waiting for the connection goroutine to exit. To correct this, a context has been added that gets passed to the connection goroutine. This is then checked in a new select statement on the connection queue which gets cancelled by tcpListener.Close() ensuring the goroutine exits correctly even if the queue is full.
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Fixes a deadlock condition that can happen if StopBgp is called when the pending connection queue is full. During teardown, StopBgp calls a mgmtOp on the server goroutine which attempts to stop the goroutine accepting inbound connections, and waits for it to finish before continuing.
This connection goroutine can block if the connection queue is full, which is read by the same goroutine that processes all mgmtOps. This means that if the queue is full and the goroutine is currently blocked, then calling StopBgp will lead to a complete deadlock, as the connection goroutine will never close as it is trying to send to the queue, but the queue will not be read as the server goroutine is currently waiting for the connection goroutine to exit.
To correct this, a context has been added that gets passed to the connection goroutine. This is then checked in a new select statement on the connection queue which gets cancelled by tcpListener.Close() ensuring the goroutine exits correctly even if the queue is full.