mirror of
https://github.com/hibiken/asynq.git
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123 lines
2.9 KiB
Go
123 lines
2.9 KiB
Go
package asynq
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import (
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"fmt"
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"log"
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"os"
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"os/signal"
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"sync"
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"syscall"
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"time"
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"github.com/hibiken/asynq/internal/rdb"
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)
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// Background is responsible for managing the background-task processing.
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//
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// Background manages background queues to process tasks and retry if
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// necessary. If the processing of a task is unsuccessful, background will
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// schedule it for a retry with an exponential backoff until either the task
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// gets processed successfully or it exhausts its max retry count.
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//
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// Once a task exhausts its retries, it will be moved to the "dead" queue and
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// will be kept in the queue for some time until a certain condition is met
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// (e.g., queue size reaches a certain limit, or the task has been in the
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// queue for a certain amount of time).
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type Background struct {
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mu sync.Mutex
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running bool
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rdb *rdb.RDB
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poller *poller
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processor *processor
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}
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// NewBackground returns a new Background with the specified number of workers
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// given a redis configuration .
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func NewBackground(numWorkers int, cfg *RedisConfig) *Background {
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r := rdb.NewRDB(newRedisClient(cfg))
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poller := newPoller(r, 5*time.Second)
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processor := newProcessor(r, numWorkers, nil)
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return &Background{
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rdb: r,
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poller: poller,
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processor: processor,
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}
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}
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// A Handler processes a task.
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//
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// ProcessTask should return nil if the processing of a task
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// is successful.
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//
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// If ProcessTask return a non-nil error or panics, the task
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// will be retried after delay.
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type Handler interface {
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ProcessTask(*Task) error
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}
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// The HandlerFunc type is an adapter to allow the use of
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// ordinary functions as a Handler. If f is a function
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// with the appropriate signature, HandlerFunc(f) is a
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// Handler that calls f.
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type HandlerFunc func(*Task) error
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// ProcessTask calls fn(task)
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func (fn HandlerFunc) ProcessTask(task *Task) error {
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return fn(task)
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}
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// Run starts the background-task processing and blocks until
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// an os signal to exit the program is received. Once it receives
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// a signal, it gracefully shuts down all pending workers and other
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// goroutines to process the tasks.
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func (bg *Background) Run(handler Handler) {
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bg.start(handler)
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defer bg.stop()
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// Wait for a signal to terminate.
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sigs := make(chan os.Signal, 1)
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signal.Notify(sigs, syscall.SIGTERM, syscall.SIGINT, syscall.SIGTSTP)
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for {
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sig := <-sigs
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if sig == syscall.SIGTSTP {
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bg.processor.stop()
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continue
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}
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break
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}
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fmt.Println()
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log.Println("[INFO] Starting graceful shutdown...")
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}
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// starts the background-task processing.
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func (bg *Background) start(handler Handler) {
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bg.mu.Lock()
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defer bg.mu.Unlock()
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if bg.running {
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return
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}
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bg.running = true
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bg.processor.handler = handler
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bg.poller.start()
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bg.processor.start()
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}
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// stops the background-task processing.
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func (bg *Background) stop() {
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bg.mu.Lock()
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defer bg.mu.Unlock()
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if !bg.running {
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return
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}
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bg.poller.terminate()
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bg.processor.terminate()
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bg.rdb.Close()
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bg.processor.handler = nil
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bg.running = false
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}
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