pools

Documentation

Overview

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

Index

• Variables
• type Factory
• type Resource
• type ResourcePool
  • func NewResourcePool(factory Factory, capacity, maxCap int, idleTimeout time.Duration) *ResourcePool
  • func (rp *ResourcePool) Available() int64
  • func (rp *ResourcePool) Capacity() int64
  • func (rp *ResourcePool) Close()
  • func (rp *ResourcePool) Get(timeout time.Duration) (resource Resource, err error)
  • func (rp *ResourcePool) IdleTimeout() time.Duration
  • func (rp *ResourcePool) IsClosed() (closed bool)
  • func (rp *ResourcePool) MaxCap() int64
  • func (rp *ResourcePool) Put(resource Resource)
  • func (rp *ResourcePool) SetCapacity(capacity int) error
  • func (rp *ResourcePool) SetIdleTimeout(idleTimeout time.Duration)
  • func (rp *ResourcePool) Stats() (capacity, available, maxCap, waitCount int64, ...)
  • func (rp *ResourcePool) StatsJSON() string
  • func (rp *ResourcePool) TryGet() (resource Resource, err error)
  • func (rp *ResourcePool) WaitCount() int64
  • func (rp *ResourcePool) WaitTime() time.Duration

Variables

var (
	CLOSED_ERR  = errors.New("resource pool is closed")
	TIMEOUT_ERR = errors.New("resource pool timed out")
)

Types

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()
}

Every resource needs to suport the Resource interface. Thread synchronization between Close() and IsClosed() is the responsibility 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) *ResourcePool

NewResourcePool creates a new ResourcePool pool. capacity is the initial capacity of the pool. maxCap is the maximum capacity. If a resource is unused beyond idleTimeout, it's discarded. An idleTimeout of 0 means that there is no timeout.

func (*ResourcePool) Available

func (rp *ResourcePool) Available() int64

func (*ResourcePool) Capacity

func (rp *ResourcePool) Capacity() int64

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 and TryGet are not allowed.

func (*ResourcePool) Get

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

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

func (*ResourcePool) IsClosed

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

func (*ResourcePool) MaxCap

func (rp *ResourcePool) MaxCap() int64

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. The will eventually 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)

func (*ResourcePool) Stats

func (rp *ResourcePool) Stats() (capacity, available, maxCap, waitCount int64, waitTime, idleTimeout time.Duration)

func (*ResourcePool) StatsJSON

func (rp *ResourcePool) StatsJSON() string

func (*ResourcePool) TryGet

func (rp *ResourcePool) TryGet() (resource Resource, err error)

TryGet will return the next available resource. If none is available, and capacity has not been reached, it will create a new one using the factory. Otherwise, it will return nil with no error.

func (*ResourcePool) WaitCount

func (rp *ResourcePool) WaitCount() int64

func (*ResourcePool) WaitTime

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