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// Copyright 2019 The Gitea Authors. All rights reserved.
// Use of this source code is governed by a MIT-style
// license that can be found in the LICENSE file.
package queue
import (
"context"
"fmt"
"reflect"
"sync"
"time"
"code.gitea.io/gitea/modules/log"
)
// WrappedQueueType is the type for a wrapped delayed starting queue
const WrappedQueueType Type = "wrapped"
// WrappedQueueConfiguration is the configuration for a WrappedQueue
type WrappedQueueConfiguration struct {
Underlying Type
Timeout time.Duration
MaxAttempts int
Config interface{}
QueueLength int
Name string
}
type delayedStarter struct {
internal Queue
underlying Type
cfg interface{}
timeout time.Duration
maxAttempts int
name string
}
// setInternal must be called with the lock locked.
func (q *delayedStarter) setInternal(atShutdown func(context.Context, func()), handle HandlerFunc, exemplar interface{}) error {
var ctx context.Context
var cancel context.CancelFunc
if q.timeout > 0 {
ctx, cancel = context.WithTimeout(context.Background(), q.timeout)
} else {
ctx, cancel = context.WithCancel(context.Background())
}
defer cancel()
// Ensure we also stop at shutdown
atShutdown(ctx, func() {
cancel()
})
i := 1
for q.internal == nil {
select {
case <-ctx.Done():
return fmt.Errorf("Timedout creating queue %v with cfg %v in %s", q.underlying, q.cfg, q.name)
default:
queue, err := NewQueue(q.underlying, handle, q.cfg, exemplar)
if err == nil {
q.internal = queue
break
}
if err.Error() != "resource temporarily unavailable" {
log.Warn("[Attempt: %d] Failed to create queue: %v for %s cfg: %v error: %v", i, q.underlying, q.name, q.cfg, err)
}
i++
if q.maxAttempts > 0 && i > q.maxAttempts {
return fmt.Errorf("Unable to create queue %v for %s with cfg %v by max attempts: error: %v", q.underlying, q.name, q.cfg, err)
}
sleepTime := 100 * time.Millisecond
if q.timeout > 0 && q.maxAttempts > 0 {
sleepTime = (q.timeout - 200*time.Millisecond) / time.Duration(q.maxAttempts)
}
t := time.NewTimer(sleepTime)
select {
case <-ctx.Done():
t.Stop()
case <-t.C:
}
}
}
return nil
}
// WrappedQueue wraps a delayed starting queue
type WrappedQueue struct {
delayedStarter
lock sync.Mutex
handle HandlerFunc
exemplar interface{}
channel chan Data
}
// NewWrappedQueue will attempt to create a queue of the provided type,
// but if there is a problem creating this queue it will instead create
// a WrappedQueue with delayed startup of the queue instead and a
// channel which will be redirected to the queue
func NewWrappedQueue(handle HandlerFunc, cfg, exemplar interface{}) (Queue, error) {
configInterface, err := toConfig(WrappedQueueConfiguration{}, cfg)
if err != nil {
return nil, err
}
config := configInterface.(WrappedQueueConfiguration)
queue, err := NewQueue(config.Underlying, handle, config.Config, exemplar)
if err == nil {
// Just return the queue there is no need to wrap
return queue, nil
}
if IsErrInvalidConfiguration(err) {
// Retrying ain't gonna make this any better...
return nil, ErrInvalidConfiguration{cfg: cfg}
}
queue = &WrappedQueue{
handle: handle,
channel: make(chan Data, config.QueueLength),
exemplar: exemplar,
delayedStarter: delayedStarter{
cfg: config.Config,
underlying: config.Underlying,
timeout: config.Timeout,
maxAttempts: config.MaxAttempts,
name: config.Name,
},
}
_ = GetManager().Add(queue, WrappedQueueType, config, exemplar, nil)
return queue, nil
}
// Name returns the name of the queue
func (q *WrappedQueue) Name() string {
return q.name + "-wrapper"
}
// Push will push the data to the internal channel checking it against the exemplar
func (q *WrappedQueue) Push(data Data) error {
if q.exemplar != nil {
// Assert data is of same type as r.exemplar
value := reflect.ValueOf(data)
t := value.Type()
exemplarType := reflect.ValueOf(q.exemplar).Type()
if !t.AssignableTo(exemplarType) || data == nil {
return fmt.Errorf("Unable to assign data: %v to same type as exemplar: %v in %s", data, q.exemplar, q.name)
}
}
q.channel <- data
return nil
}
// Run starts to run the queue and attempts to create the internal queue
func (q *WrappedQueue) Run(atShutdown, atTerminate func(context.Context, func())) {
q.lock.Lock()
if q.internal == nil {
err := q.setInternal(atShutdown, q.handle, q.exemplar)
q.lock.Unlock()
if err != nil {
log.Fatal("Unable to set the internal queue for %s Error: %v", q.Name(), err)
return
}
go func() {
for data := range q.channel {
_ = q.internal.Push(data)
}
}()
} else {
q.lock.Unlock()
}
q.internal.Run(atShutdown, atTerminate)
log.Trace("WrappedQueue: %s Done", q.name)
}
// Shutdown this queue and stop processing
func (q *WrappedQueue) Shutdown() {
log.Trace("WrappedQueue: %s Shutdown", q.name)
q.lock.Lock()
defer q.lock.Unlock()
if q.internal == nil {
return
}
if shutdownable, ok := q.internal.(Shutdownable); ok {
shutdownable.Shutdown()
}
}
// Terminate this queue and close the queue
func (q *WrappedQueue) Terminate() {
log.Trace("WrappedQueue: %s Terminating", q.name)
q.lock.Lock()
defer q.lock.Unlock()
if q.internal == nil {
return
}
if shutdownable, ok := q.internal.(Shutdownable); ok {
shutdownable.Terminate()
}
}
func init() {
queuesMap[WrappedQueueType] = NewWrappedQueue
}
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