pool

package module
v0.0.2 Latest Latest
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 Go to latest Published: Sep 10, 2020 License: Apache-2.0 Imports: 6 Imported by: 9

README

pool is a copy of a few packages from https://github.com/vitessio/vitess.

Vitess has some useful Go packages, however they are not versioned with Go modules, which causes issues (e.g. https://github.com/ThalesIgnite/crypto11/issues/56). They are also buried inside a large project, which forms a heavyweight dependency.

This package exposes the resource pool implementation and some of the atomic types.

Documentation

Overview

Package pools provides functionality to manage and reuse resources like connections.

Modified by Duncan Jones to reduce the number of external dependencies.

Package timer provides various enhanced timer functions.

Index

Constants

This section is empty.

Variables

View Source 
var (
	// ErrClosed is returned if ResourcePool is used when it's closed.
	ErrClosed = errors.New("resource pool is closed")

	// ErrTimeout is returned if a resource get times out.
	ErrTimeout = errors.New("resource pool timed out")
)

Functions

This section is empty.

Types

type AtomicBool 

type AtomicBool struct {
	// contains filtered or unexported fields
}

AtomicBool gives an atomic boolean variable.

func NewAtomicBool 

func NewAtomicBool(n bool) AtomicBool

NewAtomicBool initializes a new AtomicBool with a given value.

func (*AtomicBool) CompareAndSwap 

func (i *AtomicBool) CompareAndSwap(o, n bool) bool

CompareAndSwap atomatically swaps the old with the new value.

func (*AtomicBool) Get 

func (i *AtomicBool) Get() bool

Get atomically returns the current value.

func (*AtomicBool) Set 

func (i *AtomicBool) Set(n bool)

Set atomically sets n as new value.

type AtomicDuration 

type AtomicDuration struct {
	// contains filtered or unexported fields
}

AtomicDuration is a wrapper with a simpler interface around atomic.(Add|Store|Load|CompareAndSwap)Int64 functions.

func NewAtomicDuration 

func NewAtomicDuration(duration time.Duration) AtomicDuration

NewAtomicDuration initializes a new AtomicDuration with a given value.

func (*AtomicDuration) Add 

func (d *AtomicDuration) Add(duration time.Duration) time.Duration

Add atomically adds duration to the value.

func (*AtomicDuration) CompareAndSwap 

func (d *AtomicDuration) CompareAndSwap(oldval, newval time.Duration) (swapped bool)

CompareAndSwap atomatically swaps the old with the new value.

func (*AtomicDuration) Get 

func (d *AtomicDuration) Get() time.Duration

Get atomically returns the current value.

func (*AtomicDuration) Set 

func (d *AtomicDuration) Set(duration time.Duration)

Set atomically sets duration as new value.

type AtomicInt32 

type AtomicInt32 struct {
	// contains filtered or unexported fields
}

AtomicInt32 is a wrapper with a simpler interface around atomic.(Add|Store|Load|CompareAndSwap)Int32 functions.

func NewAtomicInt32 

func NewAtomicInt32(n int32) AtomicInt32

NewAtomicInt32 initializes a new AtomicInt32 with a given value.

func (*AtomicInt32) Add 

func (i *AtomicInt32) Add(n int32) int32

Add atomically adds n to the value.

func (*AtomicInt32) CompareAndSwap 

func (i *AtomicInt32) CompareAndSwap(oldval, newval int32) (swapped bool)

CompareAndSwap atomatically swaps the old with the new value.

func (*AtomicInt32) Get 

func (i *AtomicInt32) Get() int32

Get atomically returns the current value.

func (*AtomicInt32) Set 

func (i *AtomicInt32) Set(n int32)

Set atomically sets n as new value.

type AtomicInt64 

type AtomicInt64 struct {
	// contains filtered or unexported fields
}

AtomicInt64 is a wrapper with a simpler interface around atomic.(Add|Store|Load|CompareAndSwap)Int64 functions.

func NewAtomicInt64 

func NewAtomicInt64(n int64) AtomicInt64

NewAtomicInt64 initializes a new AtomicInt64 with a given value.

func (*AtomicInt64) Add 

func (i *AtomicInt64) Add(n int64) int64

Add atomically adds n to the value.

func (*AtomicInt64) CompareAndSwap 

func (i *AtomicInt64) CompareAndSwap(oldval, newval int64) (swapped bool)

CompareAndSwap atomatically swaps the old with the new value.

func (*AtomicInt64) Get 

func (i *AtomicInt64) Get() int64

Get atomically returns the current value.

func (*AtomicInt64) Set 

func (i *AtomicInt64) Set(n int64)

Set atomically sets n as new value.

type AtomicString 

type AtomicString struct {
	// contains filtered or unexported fields
}

AtomicString gives you atomic-style APIs for string, but it's only a convenience wrapper that uses a mutex. So, it's not as efficient as the rest of the atomic types.

func (*AtomicString) CompareAndSwap 

func (s *AtomicString) CompareAndSwap(oldval, newval string) (swqpped bool)

CompareAndSwap atomatically swaps the old with the new value.

func (*AtomicString) Get 

func (s *AtomicString) Get() string

Get atomically returns the current value.

func (*AtomicString) Set 

func (s *AtomicString) Set(str string)

Set atomically sets str as new value.

type Factory 

type Factory func() (Resource, error)

Factory is a function that can be used to create a resource.

type Resource 

type Resource interface {
	Close()
}

Resource defines the interface that every resource must provide. Thread synchronization between Close() and IsClosed() is the responsibility of the caller.

type ResourcePool 

type ResourcePool struct {
	// contains filtered or unexported fields
}

ResourcePool allows you to use a pool of resources.

func NewResourcePool 

func NewResourcePool(factory Factory, capacity, maxCap int, idleTimeout time.Duration, prefillParallelism int) *ResourcePool

NewResourcePool creates a new ResourcePool pool. capacity is the number of possible resources in the pool: there can be up to 'capacity' of these at a given time. maxCap specifies the extent to which the pool can be resized in the future through the SetCapacity function. You cannot resize the pool beyond maxCap. If a resource is unused beyond idleTimeout, it's replaced with a new one. An idleTimeout of 0 means that there is no timeout. A non-zero value of prefillParallelism causes the pool to be pre-filled. The value specifies how many resources can be opened in parallel.

func (*ResourcePool) Active 

func (rp *ResourcePool) Active() int64

Active returns the number of active (i.e. non-nil) resources either in the pool or claimed for use

func (*ResourcePool) Available 

func (rp *ResourcePool) Available() int64

Available returns the number of currently unused and available resources.

func (*ResourcePool) Capacity 

func (rp *ResourcePool) Capacity() int64

Capacity returns the capacity.

func (*ResourcePool) Close 

func (rp *ResourcePool) Close()

Close empties the pool calling Close on all its resources. You can call Close while there are outstanding resources. It waits for all resources to be returned (Put). After a Close, Get is not allowed.

func (*ResourcePool) Get 

func (rp *ResourcePool) Get(ctx context.Context) (resource Resource, err error)

Get will return the next available resource. If capacity has not been reached, it will create a new one using the factory. Otherwise, it will wait till the next resource becomes available or a timeout. A timeout of 0 is an indefinite wait.

func (*ResourcePool) IdleClosed 

func (rp *ResourcePool) IdleClosed() int64

IdleClosed returns the count of resources closed due to idle timeout.

func (*ResourcePool) IdleTimeout 

func (rp *ResourcePool) IdleTimeout() time.Duration

IdleTimeout returns the idle timeout.

func (*ResourcePool) InUse 

func (rp *ResourcePool) InUse() int64

InUse returns the number of claimed resources from the pool

func (*ResourcePool) IsClosed 

func (rp *ResourcePool) IsClosed() (closed bool)

IsClosed returns true if the resource pool is closed.

func (*ResourcePool) MaxCap 

func (rp *ResourcePool) MaxCap() int64

MaxCap returns the max capacity.

func (*ResourcePool) Put 

func (rp *ResourcePool) Put(resource Resource)

Put will return a resource to the pool. For every successful Get, a corresponding Put is required. If you no longer need a resource, you will need to call Put(nil) instead of returning the closed resource. This will cause a new resource to be created in its place.

func (*ResourcePool) SetCapacity 

func (rp *ResourcePool) SetCapacity(capacity int) error

SetCapacity changes the capacity of the pool. You can use it to shrink or expand, but not beyond the max capacity. If the change requires the pool to be shrunk, SetCapacity waits till the necessary number of resources are returned to the pool. A SetCapacity of 0 is equivalent to closing the ResourcePool.

func (*ResourcePool) SetIdleTimeout 

func (rp *ResourcePool) SetIdleTimeout(idleTimeout time.Duration)

SetIdleTimeout sets the idle timeout. It can only be used if there was an idle timeout set when the pool was created.

func (*ResourcePool) StatsJSON 

func (rp *ResourcePool) StatsJSON() string

StatsJSON returns the stats in JSON format.

func (*ResourcePool) WaitCount 

func (rp *ResourcePool) WaitCount() int64

WaitCount returns the total number of waits.

func (*ResourcePool) WaitTime 

func (rp *ResourcePool) WaitTime() time.Duration

WaitTime returns the total wait time.

type Semaphore 

type Semaphore struct {
	// contains filtered or unexported fields
}

Semaphore is a counting semaphore with the option to specify a timeout.

func NewSemaphore 

func NewSemaphore(count int, timeout time.Duration) *Semaphore

NewSemaphore creates a Semaphore. The count parameter must be a positive number. A timeout of zero means that there is no timeout.

func (*Semaphore) Acquire 

func (sem *Semaphore) Acquire() bool

Acquire returns true on successful acquisition, and false on a timeout.

func (*Semaphore) Release 

func (sem *Semaphore) Release()

Release releases the acquired semaphore. You must not release more than the number of semaphores you've acquired.

func (*Semaphore) Size 

func (sem *Semaphore) Size() int

Size returns the current number of available slots.

func (*Semaphore) TryAcquire 

func (sem *Semaphore) TryAcquire() bool

TryAcquire acquires a semaphore if it's immediately available. It returns false otherwise.

type Timer 

type Timer struct {
	// contains filtered or unexported fields
}

Timer provides timer functionality that can be controlled by the user. You start the timer by providing it a callback function, which it will call at the specified interval. 

var t = timer.NewTimer(1e9)
t.Start(KeepHouse)

func KeepHouse() {
	// do house keeping work
}

You can stop the timer by calling t.Stop, which is guaranteed to wait if KeepHouse is being executed.

You can create an untimely trigger by calling t.Trigger. You can also schedule an untimely trigger by calling t.TriggerAfter.

The timer interval can be changed on the fly by calling t.SetInterval. A zero value interval will cause the timer to wait indefinitely, and it will react only to an explicit Trigger or Stop.

func NewTimer 

func NewTimer(interval time.Duration) *Timer

NewTimer creates a new Timer object

func (*Timer) Interval 

func (tm *Timer) Interval() time.Duration

Interval returns the current interval.

func (*Timer) SetInterval 

func (tm *Timer) SetInterval(ns time.Duration)

SetInterval changes the wait interval. It will cause the timer to restart the wait.

func (*Timer) Start 

func (tm *Timer) Start(keephouse func())

Start starts the timer.

func (*Timer) Stop 

func (tm *Timer) Stop()

Stop will stop the timer. It guarantees that the timer will not execute any more calls to keephouse once it has returned.

func (*Timer) Trigger 

func (tm *Timer) Trigger()

Trigger will cause the timer to immediately execute the keephouse function. It will then cause the timer to restart the wait.

func (*Timer) TriggerAfter 

func (tm *Timer) TriggerAfter(duration time.Duration)

TriggerAfter waits for the specified duration and triggers the next event.

Source Files

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