161 lines
3.6 KiB
Go
161 lines
3.6 KiB
Go
package runners
|
|
|
|
import (
|
|
"context"
|
|
"sync"
|
|
)
|
|
|
|
// WorkerFunc represents a function processable by a worker in WorkerPool. Note
|
|
// that implementations absolutely MUST check whether passed context is Done()
|
|
// otherwise stopping the pool may block for large periods of time.
|
|
type WorkerFunc func(context.Context)
|
|
|
|
// WorkerPool provides a means of enqueuing asynchronous work.
|
|
type WorkerPool struct {
|
|
queue chan WorkerFunc
|
|
free chan struct{}
|
|
wait sync.WaitGroup
|
|
svc Service
|
|
}
|
|
|
|
// NewWorkerPool returns a new WorkerPool with provided worker count and WorkerFunc queue size.
|
|
// The number of workers represents how many WorkerFuncs can be executed simultaneously, and the
|
|
// queue size represents the max number of WorkerFuncs that can be queued at any one time.
|
|
func NewWorkerPool(workers int, queue int) WorkerPool {
|
|
return WorkerPool{
|
|
queue: make(chan WorkerFunc, queue),
|
|
free: make(chan struct{}, workers),
|
|
}
|
|
}
|
|
|
|
// Start will attempt to start the worker pool, asynchronously. Return is success state.
|
|
func (pool *WorkerPool) Start() bool {
|
|
ok := true
|
|
|
|
done := make(chan struct{})
|
|
go func() {
|
|
ok = pool.svc.Run(func(ctx context.Context) {
|
|
close(done)
|
|
pool.process(ctx)
|
|
})
|
|
if !ok {
|
|
close(done)
|
|
}
|
|
}()
|
|
<-done
|
|
|
|
return ok
|
|
}
|
|
|
|
// Stop will attempt to stop the worker pool, this will block until stopped. Return is success state.
|
|
func (pool *WorkerPool) Stop() bool {
|
|
return pool.svc.Stop()
|
|
}
|
|
|
|
// Running returns whether the worker pool is running.
|
|
func (pool *WorkerPool) Running() bool {
|
|
return pool.svc.Running()
|
|
}
|
|
|
|
// execute will take a queued function and pass it to a free worker when available.
|
|
func (pool *WorkerPool) execute(ctx context.Context, fn WorkerFunc) {
|
|
// Set as running
|
|
pool.wait.Add(1)
|
|
|
|
select {
|
|
// Pool context cancelled
|
|
case <-ctx.Done():
|
|
pool.wait.Done()
|
|
|
|
// Free worker acquired
|
|
case pool.free <- struct{}{}:
|
|
}
|
|
|
|
go func() {
|
|
defer func() {
|
|
// defer in case panic
|
|
<-pool.free
|
|
pool.wait.Done()
|
|
}()
|
|
|
|
// Run queued
|
|
fn(ctx)
|
|
}()
|
|
}
|
|
|
|
// process is the background processing routine that passes queued functions to workers.
|
|
func (pool *WorkerPool) process(ctx context.Context) {
|
|
for {
|
|
select {
|
|
// Pool context cancelled
|
|
case <-ctx.Done():
|
|
for {
|
|
select {
|
|
// Pop and execute queued
|
|
case fn := <-pool.queue:
|
|
fn(ctx) // ctx is closed
|
|
|
|
// Empty, wait for workers
|
|
default:
|
|
pool.wait.Wait()
|
|
return
|
|
}
|
|
}
|
|
|
|
// Queued func received
|
|
case fn := <-pool.queue:
|
|
pool.execute(ctx, fn)
|
|
}
|
|
}
|
|
}
|
|
|
|
// Enqueue will add provided WorkerFunc to the queue to be performed when there is a free worker.
|
|
// Note that 'fn' will ALWAYS be executed, and the supplied context will specify whether this 'fn'
|
|
// is being executed during normal pool execution, or if the pool has been stopped with <-ctx.Done().
|
|
func (pool *WorkerPool) Enqueue(fn WorkerFunc) {
|
|
// Check valid fn
|
|
if fn == nil {
|
|
return
|
|
}
|
|
|
|
select {
|
|
// Pool context cancelled
|
|
case <-pool.svc.Done():
|
|
|
|
// Placed fn in queue
|
|
case pool.queue <- fn:
|
|
}
|
|
}
|
|
|
|
// EnqueueNoBlock performs Enqueue but returns false if queue size is at max. Else, true.
|
|
func (pool *WorkerPool) EnqueueNoBlock(fn WorkerFunc) bool {
|
|
// Check valid fn
|
|
if fn == nil {
|
|
return false
|
|
}
|
|
|
|
select {
|
|
// Pool context cancelled
|
|
case <-pool.svc.Done():
|
|
return false
|
|
|
|
// Placed fn in queue
|
|
case pool.queue <- fn:
|
|
return true
|
|
|
|
// Queue is full
|
|
default:
|
|
return false
|
|
}
|
|
}
|
|
|
|
// Queue returns the number of currently queued WorkerFuncs.
|
|
func (pool *WorkerPool) Queue() int {
|
|
return len(pool.queue)
|
|
}
|
|
|
|
// Workers returns the number of currently active workers.
|
|
func (pool *WorkerPool) Workers() int {
|
|
return len(pool.free)
|
|
}
|