163 lines
3.3 KiB
Go
163 lines
3.3 KiB
Go
// Copyright 2013 Prometheus Team
|
|
// 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 utility
|
|
|
|
import (
|
|
"fmt"
|
|
"sync"
|
|
)
|
|
|
|
type state int
|
|
|
|
func (s state) String() string {
|
|
switch s {
|
|
case unstarted:
|
|
return "unstarted"
|
|
case started:
|
|
return "started"
|
|
case finished:
|
|
return "finished"
|
|
}
|
|
panic("unreachable")
|
|
}
|
|
|
|
const (
|
|
unstarted state = iota
|
|
started
|
|
finished
|
|
)
|
|
|
|
// An UncertaintyGroup models a group of operations whose result disposition is
|
|
// tenuous and needs to be validated en masse in order to make a future
|
|
// decision.
|
|
type UncertaintyGroup interface {
|
|
// Succeed makes a remark that a given action succeeded, in part.
|
|
Succeed()
|
|
// Fail makes a remark that a given action failed, in part. Nil values are
|
|
// illegal.
|
|
Fail(error)
|
|
// MayFail makes a remark that a given action either succeeded or failed. The
|
|
// determination is made by whether the error is nil.
|
|
MayFail(error)
|
|
// Wait waits for the group to have finished and emits the result of what
|
|
// occurred for the group.
|
|
Wait() (succeeded bool)
|
|
// Errors emits any errors that could have occurred.
|
|
Errors() []error
|
|
}
|
|
|
|
type uncertaintyGroup struct {
|
|
state state
|
|
remaining uint
|
|
successes uint
|
|
results chan error
|
|
anomalies []error
|
|
sync.Mutex
|
|
}
|
|
|
|
func (g *uncertaintyGroup) Succeed() {
|
|
if g.isFinished() {
|
|
panic("cannot remark when done")
|
|
}
|
|
|
|
g.results <- nil
|
|
}
|
|
|
|
func (g *uncertaintyGroup) Fail(err error) {
|
|
if g.isFinished() {
|
|
panic("cannot remark when done")
|
|
}
|
|
|
|
if err == nil {
|
|
panic("expected a failure")
|
|
}
|
|
|
|
g.results <- err
|
|
}
|
|
|
|
func (g *uncertaintyGroup) MayFail(err error) {
|
|
if g.isFinished() {
|
|
panic("cannot remark when done")
|
|
}
|
|
|
|
g.results <- err
|
|
}
|
|
|
|
func (g *uncertaintyGroup) isFinished() bool {
|
|
g.Lock()
|
|
defer g.Unlock()
|
|
|
|
return g.state == finished
|
|
}
|
|
|
|
func (g *uncertaintyGroup) finish() {
|
|
g.Lock()
|
|
defer g.Unlock()
|
|
|
|
g.state = finished
|
|
}
|
|
|
|
func (g *uncertaintyGroup) start() {
|
|
g.Lock()
|
|
defer g.Unlock()
|
|
|
|
if g.state != unstarted {
|
|
panic("cannot restart")
|
|
}
|
|
|
|
g.state = started
|
|
}
|
|
|
|
func (g *uncertaintyGroup) Wait() bool {
|
|
defer close(g.results)
|
|
g.start()
|
|
|
|
for g.remaining > 0 {
|
|
result := <-g.results
|
|
switch result {
|
|
case nil:
|
|
g.successes++
|
|
default:
|
|
g.anomalies = append(g.anomalies, result)
|
|
}
|
|
|
|
g.remaining--
|
|
}
|
|
|
|
g.finish()
|
|
|
|
return len(g.anomalies) == 0
|
|
}
|
|
|
|
func (g *uncertaintyGroup) Errors() []error {
|
|
if g.state != finished {
|
|
panic("cannot provide errors until finished")
|
|
}
|
|
|
|
return g.anomalies
|
|
}
|
|
|
|
func (g *uncertaintyGroup) String() string {
|
|
return fmt.Sprintf("UncertaintyGroup %s with %s failures", g.state, g.anomalies)
|
|
}
|
|
|
|
// NewUncertaintyGroup furnishes an UncertaintyGroup for a given set of actions
|
|
// where their quantity is known a priori.
|
|
func NewUncertaintyGroup(count uint) UncertaintyGroup {
|
|
return &uncertaintyGroup{
|
|
remaining: count,
|
|
results: make(chan error),
|
|
}
|
|
}
|