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moby--moby/daemon/events/events.go
Doug Davis 26b1064967 Add context.RequestID to event stream
This PR adds a "request ID" to each event generated, the 'docker events'
stream now looks like this:

```
2015-09-10T15:02:50.000000000-07:00 [reqid: c01e3534ddca] de7c5d4ca927253cf4e978ee9c4545161e406e9b5a14617efb52c658b249174a: (from ubuntu) create
```
Note the `[reqID: c01e3534ddca]` part, that's new.

Each HTTP request will generate its own unique ID. So, if you do a
`docker build` you'll see a series of events all with the same reqID.
This allow for log processing tools to determine which events are all related
to the same http request.

I didn't propigate the context to all possible funcs in the daemon,
I decided to just do the ones that needed it in order to get the reqID
into the events. I'd like to have people review this direction first, and
if we're ok with it then I'll make sure we're consistent about when
we pass around the context - IOW, make sure that all funcs at the same level
have a context passed in even if they don't call the log funcs - this will
ensure we're consistent w/o passing it around for all calls unnecessarily.

ping @icecrime @calavera @crosbymichael

Signed-off-by: Doug Davis <dug@us.ibm.com>
2015-09-24 11:56:37 -07:00

67 lines
1.7 KiB
Go

package events
import (
"sync"
"time"
"github.com/docker/docker/context"
"github.com/docker/docker/pkg/jsonmessage"
"github.com/docker/docker/pkg/pubsub"
)
const eventsLimit = 64
// Events is pubsub channel for *jsonmessage.JSONMessage
type Events struct {
mu sync.Mutex
events []*jsonmessage.JSONMessage
pub *pubsub.Publisher
}
// New returns new *Events instance
func New() *Events {
return &Events{
events: make([]*jsonmessage.JSONMessage, 0, eventsLimit),
pub: pubsub.NewPublisher(100*time.Millisecond, 1024),
}
}
// Subscribe adds new listener to events, returns slice of 64 stored last events
// channel in which you can expect new events in form of interface{}, so you
// need type assertion.
func (e *Events) Subscribe() ([]*jsonmessage.JSONMessage, chan interface{}) {
e.mu.Lock()
current := make([]*jsonmessage.JSONMessage, len(e.events))
copy(current, e.events)
l := e.pub.Subscribe()
e.mu.Unlock()
return current, l
}
// Evict evicts listener from pubsub
func (e *Events) Evict(l chan interface{}) {
e.pub.Evict(l)
}
// Log broadcasts event to listeners. Each listener has 100 millisecond for
// receiving event or it will be skipped.
func (e *Events) Log(ctx context.Context, action, id, from string) {
now := time.Now().UTC()
jm := &jsonmessage.JSONMessage{RequestID: ctx.RequestID(), Status: action, ID: id, From: from, Time: now.Unix(), TimeNano: now.UnixNano()}
e.mu.Lock()
if len(e.events) == cap(e.events) {
// discard oldest event
copy(e.events, e.events[1:])
e.events[len(e.events)-1] = jm
} else {
e.events = append(e.events, jm)
}
e.mu.Unlock()
e.pub.Publish(jm)
}
// SubscribersCount returns number of event listeners
func (e *Events) SubscribersCount() int {
return e.pub.Len()
}