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// Copyright 2020 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 (
"fmt"
"sync"
"time"
)
// WrappedUniqueQueueType is the type for a wrapped delayed starting queue
const WrappedUniqueQueueType Type = "unique-wrapped"
// WrappedUniqueQueueConfiguration is the configuration for a WrappedUniqueQueue
type WrappedUniqueQueueConfiguration struct {
Underlying Type
Timeout time.Duration
MaxAttempts int
Config interface{}
QueueLength int
Name string
}
// WrappedUniqueQueue wraps a delayed starting unique queue
type WrappedUniqueQueue struct {
*WrappedQueue
table map[Data]bool
tlock sync.Mutex
ready bool
}
// NewWrappedUniqueQueue will attempt to create a unique queue of the provided type,
// but if there is a problem creating this queue it will instead create
// a WrappedUniqueQueue with delayed startup of the queue instead and a
// channel which will be redirected to the queue
//
// Please note that this Queue does not guarantee that a particular
// task cannot be processed twice or more at the same time. Uniqueness is
// only guaranteed whilst the task is waiting in the queue.
func NewWrappedUniqueQueue(handle HandlerFunc, cfg, exemplar interface{}) (Queue, error) {
configInterface, err := toConfig(WrappedUniqueQueueConfiguration{}, cfg)
if err != nil {
return nil, err
}
config := configInterface.(WrappedUniqueQueueConfiguration)
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}
}
wrapped := &WrappedUniqueQueue{
WrappedQueue: &WrappedQueue{
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,
},
},
table: map[Data]bool{},
}
// wrapped.handle is passed to the delayedStarting internal queue and is run to handle
// data passed to
wrapped.handle = func(data ...Data) (unhandled []Data) {
for _, datum := range data {
wrapped.tlock.Lock()
if !wrapped.ready {
delete(wrapped.table, data)
// If our table is empty all of the requests we have buffered between the
// wrapper queue starting and the internal queue starting have been handled.
// We can stop buffering requests in our local table and just pass Push
// direct to the internal queue
if len(wrapped.table) == 0 {
wrapped.ready = true
}
}
wrapped.tlock.Unlock()
if u := handle(datum); u != nil {
unhandled = append(unhandled, u...)
}
}
return unhandled
}
_ = GetManager().Add(queue, WrappedUniqueQueueType, config, exemplar)
return wrapped, nil
}
// Push will push the data to the internal channel checking it against the exemplar
func (q *WrappedUniqueQueue) Push(data Data) error {
return q.PushFunc(data, nil)
}
// PushFunc will push the data to the internal channel checking it against the exemplar
func (q *WrappedUniqueQueue) PushFunc(data Data, fn func() error) error {
if !assignableTo(data, q.exemplar) {
return fmt.Errorf("Unable to assign data: %v to same type as exemplar: %v in %s", data, q.exemplar, q.name)
}
q.tlock.Lock()
if q.ready {
// ready means our table is empty and all of the requests we have buffered between the
// wrapper queue starting and the internal queue starting have been handled.
// We can stop buffering requests in our local table and just pass Push
// direct to the internal queue
q.tlock.Unlock()
return q.internal.(UniqueQueue).PushFunc(data, fn)
}
locked := true
defer func() {
if locked {
q.tlock.Unlock()
}
}()
if _, ok := q.table[data]; ok {
return ErrAlreadyInQueue
}
// FIXME: We probably need to implement some sort of limit here
// If the downstream queue blocks this table will grow without limit
q.table[data] = true
if fn != nil {
err := fn()
if err != nil {
delete(q.table, data)
return err
}
}
locked = false
q.tlock.Unlock()
q.channel <- data
return nil
}
// Has checks if the data is in the queue
func (q *WrappedUniqueQueue) Has(data Data) (bool, error) {
q.tlock.Lock()
defer q.tlock.Unlock()
if q.ready {
return q.internal.(UniqueQueue).Has(data)
}
_, has := q.table[data]
return has, nil
}
// IsEmpty checks whether the queue is empty
func (q *WrappedUniqueQueue) IsEmpty() bool {
q.tlock.Lock()
if len(q.table) > 0 {
q.tlock.Unlock()
return false
}
if q.ready {
q.tlock.Unlock()
return q.internal.IsEmpty()
}
q.tlock.Unlock()
return false
}
func init() {
queuesMap[WrappedUniqueQueueType] = NewWrappedUniqueQueue
}
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