grpcpool

README

grpc-go-pool

This package aims to provide an easy to use and lightweight GRPC connection pool.

Please note that the goal isn't to replicate the client-side load-balancing feature of the official grpc package: the goal is rather to have multiple connections established to one endpoint (which can be server-side load-balanced).

Documentation

Overview

Package grpcpool provides a pool of grpc clients

Index

• Variables
• type ClientConn
  • func (c *ClientConn) Close() error
  • func (c *ClientConn) Unhealthy()
• type Factory
• type FactoryWithContext
• type Pool
  • func New(factory Factory, init, capacity int, idleTimeout time.Duration, ...) (*Pool, error)
  • func NewWithContext(ctx context.Context, factory FactoryWithContext, init, capacity int, ...) (*Pool, error)
  • func (p *Pool) Capacity() int
  • func (p *Pool) Close()
  • func (p *Pool) Get(ctx context.Context) (*ClientConn, error)
  • func (p *Pool) IsClosed() bool

Variables

var (
	// ErrClosed is the error when the client pool is closed
	ErrClosed = errors.New("grpc pool: client pool is closed")
	// ErrTimeout is the error when the client pool timed out
	ErrTimeout = errors.New("grpc pool: client pool timed out")
	// ErrAlreadyClosed is the error when the client conn was already closed
	ErrAlreadyClosed = errors.New("grpc pool: the connection was already closed")
	// ErrFullPool is the error when the pool is already full
	ErrFullPool = errors.New("grpc pool: closing a ClientConn into a full pool")
)

Types

type ClientConn

type ClientConn struct {
	*grpc.ClientConn
	// contains filtered or unexported fields
}

ClientConn is the wrapper for a grpc client conn

func (*ClientConn) Close

func (c *ClientConn) Close() error

Close 'returns' a ClientConn to the pool. It is safe to call multiple time, but will return an error after first time. Note that grpc connections can be safeuly utilized concurrently by many clients. Therefore there's no real need to grant exclusive use of a connection to one client at a time.

func (*ClientConn) Unhealthy

func (c *ClientConn) Unhealthy()

Unhealthy marks the client conn as unhealthy, so that the connection gets reset when closed.

type Factory

type Factory func() (*grpc.ClientConn, error)

Factory is a function type creating a grpc client

type FactoryWithContext

type FactoryWithContext func(context.Context) (*grpc.ClientConn, error)

FactoryWithContext is a function type creating a grpc client that accepts the context parameter that could be passed from Get or NewWithContext method.

type Pool

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

Pool is the grpc client pool

func New

func New(factory Factory, init, capacity int, idleTimeout time.Duration,
	maxLifeDuration ...time.Duration,
) (*Pool, error)

New creates a new clients pool with the given initial and maximum capacity, and the timeout for the idle clients. Returns an error if the initial clients could not be created

func NewWithContext

func NewWithContext(ctx context.Context, factory FactoryWithContext, init, capacity int, idleTimeout time.Duration,
	maxLifeDuration ...time.Duration,
) (*Pool, error)

NewWithContext creates a new clients pool with the given initial and maximum capacity, and the timeout for the idle clients. The context parameter would be passed to the factory method during initialization. Returns an error if the initial clients could not be created.

func (*Pool) Capacity

func (p *Pool) Capacity() int

Capacity returns the capacity

func (*Pool) Close

func (p *Pool) Close()

Close empties the pool calling Close on all its clients. You can call Close while there are outstanding clients. The pool channel is then closed, and Get will not be allowed anymore

func (*Pool) Get

func (p *Pool) Get(ctx context.Context) (*ClientConn, error)

Get will return the next available client. If capacity has not been reached, it will create a new one using the factory.

func (*Pool) IsClosed

func (p *Pool) IsClosed() bool

IsClosed returns true if the client pool is closed.