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clientv3: document context to "Watch" API 

Signed-off-by: Gyuho Lee <gyuhox@gmail.com>
release-3.4
Gyuho Lee 2017-12-14 14:07:50 -08:00
parent c8dc19bf4b
commit f6f3a9ca69
1 changed files with 14 additions and 0 deletions
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14
clientv3/watch.go
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@ -46,6 +46,20 @@ type Watcher interface {
// through the returned channel. If revisions waiting to be sent over the
// watch are compacted, then the watch will be canceled by the server, the
// client will post a compacted error watch response, and the channel will close.
// If the context "ctx" is canceled or timed out, returned "WatchChan" is closed,
// and "WatchResponse" from this closed channel has zero events and nil "Err()".
// If the context is "context.Background/TODO", returned "WatchChan" will not be closed
// and wait until events happen, except when server returns a non-recoverable error.
// For example, when context passed with "WithRequireLeader" and the connected server
// has no leader, error "etcdserver: no leader" is returned, and then "WatchChan" is
// closed with non-nil "Err()".
// Otherwise, as long as the context has not been canceled or timed out, watch will
// retry on other recoverable errors forever until reconnected.
//
// TODO: explicitly set context error in the last "WatchResponse" message and close channel?
// Currently, client contexts are overwritten with "valCtx" that never closes.
// TODO(v3.4): configure watch retry policy, limit maximum retry number
// (see https://github.com/coreos/etcd/issues/8980)
Watch(ctx context.Context, key string, opts ...OpOption) WatchChan
// Close closes the watcher and cancels all watch requests.