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This way provide both Time and TimeNano in the event. For the display of the JSONMessage, use either, but prefer TimeNano Proving only TimeNano would break Subscribers that are using the `Time` field, so both are set for backwards compatibility. The events logging uses nano formatting, but only provides a Unix() time, therefor ordering may get lost in the output. Example: ``` 2015-09-15T14:18:51.000000000-04:00 ee46febd64ac629f7de9cd8bf58582e6f263d97ff46896adc5b508db804682da: (from busybox) resize 2015-09-15T14:18:51.000000000-04:00 a78c9149b1c0474502a117efaa814541926c2ae6ec3c76607e1c931b84c3a44b: (from busybox) resize ``` By having a field just for Nano time, when set, the marshalling back to `time.Unix(sec int64, nsec int64)` has zeros exactly where it needs to. This does not break any existing use of jsonmessage.JSONMessage, but now allows for use of `UnixNano()` and get event formatting that has distinguishable order. Example: ``` 2015-09-15T15:37:23.810295632-04:00 6adcf8ed9f5f5ec059a915466cd1cde86a18b4a085fc3af405e9cc9fecbbbbaf: (from busybox) resize 2015-09-15T15:37:23.810412202-04:00 6b7c5bfdc3f902096f5a91e628f21bd4b56e32590c5b4b97044aafc005ddcb0d: (from busybox) resize ``` Including tests for TimeNano and updated event API reference doc. Signed-off-by: Vincent Batts <vbatts@redhat.com>
65 lines
1.6 KiB
Go
65 lines
1.6 KiB
Go
package events
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import (
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"sync"
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"time"
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"github.com/docker/docker/pkg/jsonmessage"
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"github.com/docker/docker/pkg/pubsub"
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)
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const eventsLimit = 64
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// Events is pubsub channel for *jsonmessage.JSONMessage
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type Events struct {
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mu sync.Mutex
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events []*jsonmessage.JSONMessage
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pub *pubsub.Publisher
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}
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// New returns new *Events instance
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func New() *Events {
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return &Events{
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events: make([]*jsonmessage.JSONMessage, 0, eventsLimit),
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pub: pubsub.NewPublisher(100*time.Millisecond, 1024),
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}
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}
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// Subscribe adds new listener to events, returns slice of 64 stored last events
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// channel in which you can expect new events in form of interface{}, so you
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// need type assertion.
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func (e *Events) Subscribe() ([]*jsonmessage.JSONMessage, chan interface{}) {
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e.mu.Lock()
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current := make([]*jsonmessage.JSONMessage, len(e.events))
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copy(current, e.events)
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l := e.pub.Subscribe()
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e.mu.Unlock()
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return current, l
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}
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// Evict evicts listener from pubsub
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func (e *Events) Evict(l chan interface{}) {
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e.pub.Evict(l)
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}
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// Log broadcasts event to listeners. Each listener has 100 millisecond for
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// receiving event or it will be skipped.
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func (e *Events) Log(action, id, from string) {
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now := time.Now().UTC()
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jm := &jsonmessage.JSONMessage{Status: action, ID: id, From: from, Time: now.Unix(), TimeNano: now.UnixNano()}
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e.mu.Lock()
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if len(e.events) == cap(e.events) {
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// discard oldest event
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copy(e.events, e.events[1:])
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e.events[len(e.events)-1] = jm
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} else {
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e.events = append(e.events, jm)
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}
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e.mu.Unlock()
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e.pub.Publish(jm)
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}
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// SubscribersCount returns number of event listeners
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func (e *Events) SubscribersCount() int {
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return e.pub.Len()
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}
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