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Prevent blocking on RPC server messages after shutdown.

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This change adds select statements to each channel write that may
occur from a non-RPCS goroutine to unblock once the server has begun
shutting down.  This prevents issues in clean shutdown where non-RPCS
goroutines may block indefinitely on message sends to the RPC server.
This commit is contained in:
Josh Rickmar 2014-03-21 18:07:36 -05:00
parent 715fd22de9
commit 29dd411457
1 changed files with 32 additions and 5 deletions
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37
rpcwebsocket.go
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@ -181,13 +181,27 @@ func (m *wsNotificationManager) queueHandler() {
// to the notification manager for block and transaction notification
// processing.
func (m *wsNotificationManager) NotifyBlockConnected(block *btcutil.Block) {
m.queueNotification <- (*notificationBlockConnected)(block)
// As NotifyBlockConnected will be called by the block manager
// and the RPC server may no longer be running, use a select
// statement to unblock enqueueing the notification once the RPC
// server has begun shutting down.
select {
case m.queueNotification <- (*notificationBlockConnected)(block):
case <-m.quit:
}
}
// NotifyBlockDisconnected passes a block disconnected from the best chain
// to the notification manager for block notification processing.
func (m *wsNotificationManager) NotifyBlockDisconnected(block *btcutil.Block) {
m.queueNotification <- (*notificationBlockDisconnected)(block)
// As NotifyBlockDisconnected will be called by the block manager
// and the RPC server may no longer be running, use a select
// statement to unblock enqueueing the notification once the RPC
// server has begun shutting down.
select {
case m.queueNotification <- (*notificationBlockDisconnected)(block):
case <-m.quit:
}
}
// NotifyMempoolTx passes a transaction accepted by mempool to the
@ -195,10 +209,19 @@ func (m *wsNotificationManager) NotifyBlockDisconnected(block *btcutil.Block) {
// isNew is true, the tx is is a new transaction, rather than one
// added to the mempool during a reorg.
func (m *wsNotificationManager) NotifyMempoolTx(tx *btcutil.Tx, isNew bool) {
m.queueNotification <- &notificationTxAcceptedByMempool{
n := &notificationTxAcceptedByMempool{
isNew: isNew,
tx: tx,
}
// As NotifyMempoolTx will be called by mempool and the RPC server
// may no longer be running, use a select statement to unblock
// enqueueing the notification once the RPC server has begun
// shutting down.
select {
case m.queueNotification <- n:
case <-m.quit:
}
}
// Notification types
@ -354,8 +377,12 @@ out:
}
// NumClients returns the number of clients actively being served.
func (m *wsNotificationManager) NumClients() int {
return <-m.numClients
func (m *wsNotificationManager) NumClients() (n int) {
select {
case n = <-m.numClients:
case <-m.quit: // Use default n (0) if server has shut down.
}
return
}
// RegisterBlockUpdates requests block update notifications to the passed