115 lines
2.6 KiB
Go
115 lines
2.6 KiB
Go
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// pool with support for:
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// - finalizing items
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// - monitoring: events and/or stats
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// - adaptive shrinking algorithm
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// - custom shrinking algorithms
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package pool
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import (
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"errors"
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"time"
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)
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type Stats struct {
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Idle int
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Active int
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Get int
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Put int
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Alloc int
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Free int
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}
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type EventType int
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const (
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None EventType = 0
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GetOperation EventType = 1 << iota
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PutOperation
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AllocateOperation
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FreeOperation
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AllocateError
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)
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type Event struct {
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Type EventType
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Stats Stats
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}
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type Algo interface {
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// always called
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// desired idle items
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// implementations should consider the cost of freeing the stored resources
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// must support being called from a goroutine other than it was created in
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// a single pool instance only calls it from a single goroutine at a time
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// items need to be allocated always by calling Get
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// second return argument for requested next check
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Target(Stats) (int, time.Duration)
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}
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type Options struct {
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// events can be dropped if the consumer is blocked
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Events chan<- Event
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EventMask EventType
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Algo Algo
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}
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type Pool[R any] struct {
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pool pool[R]
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}
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var ErrEmptyPool = errors.New("empty pool")
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// zero-config
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func Adaptive() Algo {
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return makeAdaptiveAlgo()
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}
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// enfoces a max pool size and a timeout for the items
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// when adding items to the pool via Put that were not fetched via Get, there can discrepancies occur in which
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// items get timed out, but the general pool limitations get still consistently enforced eventually
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func MaxTimeout(max int, to time.Duration) Algo {
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return makeMaxTimeout(max, to)
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}
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// like MaxTimeout but without enforcing timeouts
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func Max(max int) Algo {
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return makeMaxTimeout(max, 0)
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}
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// like MaxTimeout but without enforcing max pool size
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func Timeout(to time.Duration) Algo {
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return makeMaxTimeout(0, to)
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}
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// the user code can decide not to put back items to the pool
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func NoShrink() Algo {
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return makeMaxTimeout(0, 0)
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}
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// alloc and free need to support calls from goroutines other than they were created in
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// a single pool instance only calls them from a single goroutine at a time
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// free happens synchronously, user code may execute it in the background, in which case it is the user code's
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// responsibility to ensure that free is fully carried out before the application exits, if that's necessary
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func Make[R any](alloc func() (R, error), free func(R), o Options) Pool[R] {
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return Pool[R]{pool: makePool(alloc, free, o)}
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}
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func (p Pool[R]) Get() (R, error) {
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return p.pool.get()
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}
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func (p Pool[R]) Put(i R) {
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p.pool.put(i)
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}
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func (p Pool[R]) Stats() Stats {
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return p.pool.stats()
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}
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func (p Pool[R]) Free() {
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p.pool.freePool()
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}
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