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561974308d
The curator requires the existence of a curator remark table, which stores the progress for a given curation policy. The tests for the curator create an ad hoc table, but core Prometheus presently lacks said table, which this commit adds. Secondarily, the error handling for the LevelDB lifecycle functions in the metric persistence have been wrapped into an UncertaintyGroup, which mirrors some of the functions of sync.WaitGroup but adds error capturing capability to the mix.
141 lines
3 KiB
Go
141 lines
3 KiB
Go
// Copyright 2013 Prometheus Team
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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package utility
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import (
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"fmt"
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)
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type state int
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func (s state) String() string {
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switch s {
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case unstarted:
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return "unstarted"
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case started:
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return "started"
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case finished:
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return "finished"
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}
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panic("unreachable")
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}
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const (
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unstarted state = iota
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started
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finished
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)
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// An UncertaintyGroup models a group of operations whose result disposition is
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// tenuous and needs to be validated en masse in order to make a future
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// decision.
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type UncertaintyGroup interface {
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// Succeed makes a remark that a given action succeeded, in part.
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Succeed()
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// Fail makes a remark that a given action failed, in part. Nil values are
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// illegal.
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Fail(error)
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// MayFail makes a remark that a given action either succeeded or failed. The
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// determination is made by whether the error is nil.
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MayFail(error)
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// Wait waits for the group to have finished and emits the result of what
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// occurred for the group.
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Wait() (succeeded bool)
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// Errors emits any errors that could have occurred.
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Errors() []error
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}
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type uncertaintyGroup struct {
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state state
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remaining uint
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successes uint
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results chan error
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anomalies []error
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}
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func (g uncertaintyGroup) Succeed() {
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if g.state == finished {
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panic("cannot remark when done")
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}
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g.results <- nil
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}
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func (g uncertaintyGroup) Fail(err error) {
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if g.state == finished {
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panic("cannot remark when done")
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}
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if err == nil {
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panic("expected a failure")
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}
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g.results <- err
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}
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func (g uncertaintyGroup) MayFail(err error) {
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if g.state == finished {
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panic("cannot remark when done")
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}
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g.results <- err
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}
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func (g *uncertaintyGroup) Wait() bool {
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if g.state != unstarted {
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panic("cannot restart")
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}
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defer close(g.results)
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g.state = started
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for g.remaining > 0 {
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result := <-g.results
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switch result {
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case nil:
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g.successes++
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default:
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g.anomalies = append(g.anomalies, result)
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}
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g.remaining--
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}
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g.state = finished
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return len(g.anomalies) == 0
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}
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func (g uncertaintyGroup) Errors() []error {
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if g.state != finished {
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panic("cannot provide errors until finished")
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}
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return g.anomalies
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}
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func (g uncertaintyGroup) String() string {
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return fmt.Sprintf("UncertaintyGroup %s with %s failures", g.state, g.anomalies)
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}
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// NewUncertaintyGroup furnishes an UncertaintyGroup for a given set of actions
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// where their quantity is known a priori.
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func NewUncertaintyGroup(count uint) UncertaintyGroup {
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return &uncertaintyGroup{
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remaining: count,
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results: make(chan error),
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}
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}
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