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// Copyright 2017, OpenCensus Authors
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
//
package view
import (
"errors"
"fmt"
"strings"
"time"
"go.opencensus.io/stats"
"go.opencensus.io/stats/internal"
"go.opencensus.io/tag"
)
type command interface {
handleCommand(w *worker)
}
// getViewByNameReq is the command to get a view given its name.
type getViewByNameReq struct {
name string
c chan *getViewByNameResp
}
type getViewByNameResp struct {
v *View
}
func (cmd *getViewByNameReq) handleCommand(w *worker) {
v := w.views[cmd.name]
if v == nil {
cmd.c <- &getViewByNameResp{nil}
return
}
cmd.c <- &getViewByNameResp{v.view}
}
// registerViewReq is the command to register a view.
type registerViewReq struct {
views []*View
err chan error
}
func (cmd *registerViewReq) handleCommand(w *worker) {
var errstr []string
for _, view := range cmd.views {
vi, err := w.tryRegisterView(view)
if err != nil {
errstr = append(errstr, fmt.Sprintf("%s: %v", view.Name, err))
continue
}
internal.SubscriptionReporter(view.Measure.Name())
vi.subscribe()
}
if len(errstr) > 0 {
cmd.err <- errors.New(strings.Join(errstr, "\n"))
} else {
cmd.err <- nil
}
}
// unregisterFromViewReq is the command to unsubscribe to a view. Has no
// impact on the data collection for client that are pulling data from the
// library.
type unregisterFromViewReq struct {
views []string
done chan struct{}
}
func (cmd *unregisterFromViewReq) handleCommand(w *worker) {
for _, name := range cmd.views {
vi, ok := w.views[name]
if !ok {
continue
}
vi.unsubscribe()
if !vi.isSubscribed() {
// this was the last subscription and view is not collecting anymore.
// The collected data can be cleared.
vi.clearRows()
}
delete(w.views, name)
}
cmd.done <- struct{}{}
}
// retrieveDataReq is the command to retrieve data for a view.
type retrieveDataReq struct {
now time.Time
v string
c chan *retrieveDataResp
}
type retrieveDataResp struct {
rows []*Row
err error
}
func (cmd *retrieveDataReq) handleCommand(w *worker) {
vi, ok := w.views[cmd.v]
if !ok {
cmd.c <- &retrieveDataResp{
nil,
fmt.Errorf("cannot retrieve data; view %q is not registered", cmd.v),
}
return
}
if !vi.isSubscribed() {
cmd.c <- &retrieveDataResp{
nil,
fmt.Errorf("cannot retrieve data; view %q has no subscriptions or collection is not forcibly started", cmd.v),
}
return
}
cmd.c <- &retrieveDataResp{
vi.collectedRows(),
nil,
}
}
// recordReq is the command to record data related to multiple measures
// at once.
type recordReq struct {
tm *tag.Map
ms []stats.Measurement
}
func (cmd *recordReq) handleCommand(w *worker) {
for _, m := range cmd.ms {
if (m == stats.Measurement{}) { // not subscribed
continue
}
ref := w.getMeasureRef(m.Measure().Name())
for v := range ref.views {
v.addSample(cmd.tm, m.Value())
}
}
}
// setReportingPeriodReq is the command to modify the duration between
// reporting the collected data to the subscribed clients.
type setReportingPeriodReq struct {
d time.Duration
c chan bool
}
func (cmd *setReportingPeriodReq) handleCommand(w *worker) {
w.timer.Stop()
if cmd.d <= 0 {
w.timer = time.NewTicker(defaultReportingDuration)
} else {
w.timer = time.NewTicker(cmd.d)
}
cmd.c <- true
}
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