pool

README

Pool

Pool is a thread safe connection pool for net.Conn interface. It can be used to manage and reuse connections.

Install and Usage

Install the package with:

go get github.com/fatih/pool

Please vendor the package with one of the releases: https://github.com/fatih/pool/releases. master branch is development branch and will contain always the latest changes.

Example

// create a factory() to be used with channel based pool
factory    := func() (net.Conn, error) { return net.Dial("tcp", "127.0.0.1:4000") }

// create a new channel based pool with an initial capacity of 5 and maximum
// capacity of 30. The factory will create 5 initial connections and put it
// into the pool.
p, err := pool.NewChannelPool(5, 30, factory)

// now you can get a connection from the pool, if there is no connection
// available it will create a new one via the factory function.
conn, err := p.Get()

// do something with conn and put it back to the pool by closing the connection
// (this doesn't close the underlying connection instead it's putting it back
// to the pool).
conn.Close()

// close the underlying connection instead of returning it to pool
// it is useful when acceptor has already closed connection and conn.Write() returns error
if pc, ok := conn.(*pool.PoolConn); ok {
  pc.MarkUnusable()
  pc.Close()
}

// close pool any time you want, this closes all the connections inside a pool
p.Close()

// currently available connections in the pool
current := p.Len()

Credits

• Fatih Arslan
• sougou

License

The MIT License (MIT) - see LICENSE for more details

Documentation

Overview

Package pool implements a pool of net.Conn interfaces to manage and reuse them.

Index

• Variables
• type Factory
• type Pool
  • func NewChannelPool(initialCap, maxCap int, factory Factory) (Pool, error)
• type PoolConn
  • func (p *PoolConn) Close() error
  • func (p *PoolConn) MarkUnusable()

Variables

var (
	// ErrClosed is the error resulting if the pool is closed via pool.Close().
	ErrClosed = errors.New("pool is closed")
)

Types

type Factory

type Factory func() (net.Conn, error)

Factory is a function to create new connections.

type Pool

type Pool interface {
	// Get returns a new connection from the pool. Closing the connections puts
	// it back to the Pool. Closing it when the pool is destroyed or full will
	// be counted as an error.
	Get() (net.Conn, error)

	// Close closes the pool and all its connections. After Close() the pool is
	// no longer usable.
	Close()

	// Len returns the current number of connections of the pool.
	Len() int
}

Pool interface describes a pool implementation. A pool should have maximum capacity. An ideal pool is threadsafe and easy to use.

func NewChannelPool

func NewChannelPool(initialCap, maxCap int, factory Factory) (Pool, error)

NewChannelPool returns a new pool based on buffered channels with an initial capacity and maximum capacity. Factory is used when initial capacity is greater than zero to fill the pool. A zero initialCap doesn't fill the Pool until a new Get() is called. During a Get(), If there is no new connection available in the pool, a new connection will be created via the Factory() method.

type PoolConn

type PoolConn struct {
	net.Conn
	// contains filtered or unexported fields
}

PoolConn is a wrapper around net.Conn to modify the the behavior of net.Conn's Close() method.

func (*PoolConn) Close

func (p *PoolConn) Close() error

Close() puts the given connects back to the pool instead of closing it.

func (*PoolConn) MarkUnusable

func (p *PoolConn) MarkUnusable()

MarkUnusable() marks the connection not usable any more, to let the pool close it instead of returning it to pool.