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timers.go
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timers.go
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/* Copyright 2018 Comcast Cable Communications Management, LLC
* 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 main
// ToDo: Timers.Suspend, Timers.Resune
import (
"context"
"encoding/json"
"errors"
"fmt"
"log"
"sync"
"time"
. "github.com/Comcast/sheens/util/testutil"
)
type Emitter func(ctx context.Context, message interface{}) error
var (
Exists = errors.New("id exists")
NotFound = errors.New("not found")
)
type TimerEntry struct {
Id string `json:"id"`
Message interface{} `json:"message"`
At time.Time `json:"at"`
ctl chan bool
}
type Timers struct {
Errors chan interface{} `json:"-" yaml:"-"`
sync.Mutex
timers map[string]*TimerEntry `json:"map"`
ctl chan bool
emit Emitter
}
func NewTimers(emitter Emitter) *Timers {
return &Timers{
timers: make(map[string]*TimerEntry, 32),
emit: emitter,
ctl: make(chan bool),
}
}
func (ts *Timers) MarshalJSON() ([]byte, error) {
ts.Lock()
m := map[string]interface{}{
"map": ts.timers,
}
bs, err := json.Marshal(&m)
ts.Unlock()
return bs, err
}
func (ts *Timers) MarshalYAML() (interface{}, error) {
ts.Lock()
cp := Copy(map[string]interface{}{
"map": ts.timers,
})
ts.Unlock()
return cp, nil
}
func (ts *Timers) Add(ctx context.Context, id string, message interface{}, in time.Duration) error {
ts.Lock()
defer ts.Unlock()
if _, have := ts.timers[id]; have {
return Exists
}
te := &TimerEntry{
Id: id,
Message: message,
At: time.Now().UTC().Add(in),
ctl: make(chan bool),
}
ts.timers[id] = te
stop := func() {
if err := ts.Rem(ctx, id); err != nil {
ts.err(fmt.Errorf("Timers rem error %v id=%s", err, id))
}
}
go func() {
timer := time.NewTimer(te.At.Sub(time.Now()))
select {
case <-ctx.Done():
stop()
case <-te.ctl:
// We only get here via a Rem() call.
case <-ts.ctl:
stop()
// Not exactly what we want ...
case <-timer.C:
Logf("Timers firing %s", JS(ts))
if err := ts.emit(ctx, te.Message); err != nil {
ts.err(fmt.Errorf("Timers emit error %v id=%s", err, id))
}
// See https://github.com/Comcast/sheens/issues/19
ts.Lock()
delete(ts.timers, id)
ts.Unlock()
}
}()
return nil
}
func (ts *Timers) Shutdown() error {
close(ts.ctl)
return nil
}
func (ts *Timers) Rem(ctx context.Context, id string) error {
ts.Lock()
defer ts.Unlock()
te, have := ts.timers[id]
if !have {
return NotFound
}
delete(ts.timers, id)
close(te.ctl)
return nil
}
func (ts *Timers) err(err error) {
if ts.Errors != nil {
ts.Errors <- err
} else {
log.Println(err)
}
}