pool: new pool interface, change to the API

channel.go

@@ -0,0 +1,127 @@
+// Package pool implements a pool of net.Conn interfaces to manage and reuse them.
+package pool
+
+import (
+	"errors"
+	"fmt"
+	"net"
+	"sync"
+)
+
+// Pool allows you to use a pool of net.Conn connections.
+type ChannelPool struct {
+	// storage for our net.Conn connections
+	mu    sync.Mutex
+	conns chan net.Conn
+
+	// net.Conn generator
+	factory Factory
+}
+
+// Factory is a function to create new connections.
+type Factory func() (net.Conn, 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.
+func NewChannelPool(initialCap, maxCap int, factory Factory) (Pool, error) {
+	if initialCap <= 0 || maxCap <= 0 || initialCap > maxCap {
+		return nil, errors.New("invalid capacity settings")
+	}
+
+	c := &ChannelPool{
+		conns:   make(chan net.Conn, maxCap),
+		factory: factory,
+	}
+
+	// create initial connections, if something goes wrong,
+	// just close the pool error out.
+	for i := 0; i < initialCap; i++ {
+		conn, err := factory()
+		if err != nil {
+			c.Close()
+			return nil, fmt.Errorf("factory is not able to fill the pool: %s", err)
+		}
+		c.conns <- conn
+	}
+
+	return c, nil
+}
+
+func (c *ChannelPool) getConns() chan net.Conn {
+	c.mu.Lock()
+	conns := c.conns
+	c.mu.Unlock()
+	return conns
+}
+
+// Get returns a new connection from the pool. After using the connection it
+// should be put back via the Put() method. If there is no new connection
+// available in the pool, a new connection will be created via the Factory()
+// method.
+func (c *ChannelPool) Get() (net.Conn, error) {
+	conns := c.getConns()
+	if conns == nil {
+		return nil, ErrPoolClosed
+	}
+
+	select {
+	case conn := <-conns:
+		if conn == nil {
+			return nil, ErrPoolClosed
+		}
+		return conn, nil
+	default:
+		return c.factory()
+	}
+}
+
+// Put puts an existing connection into the pool. If the pool is full or
+// closed, conn is simply closed. A nil conn will be rejected. Putting into a
+// destroyed or full pool will be counted as an error.
+func (c *ChannelPool) Put(conn net.Conn) error {
+	if conn == nil {
+		return errors.New("connection is nil. rejecting")
+	}
+
+	c.mu.Lock()
+	defer c.mu.Unlock()
+
+	if c.conns == nil {
+		conn.Close()
+		return ErrPoolClosed
+	}
+
+	select {
+	case c.conns <- conn:
+		return nil
+	default:
+		conn.Close()
+		return ErrPoolFull
+	}
+}
+
+// Close closes the pool and all its connections. After Close() the
+// pool is no longer usable.
+func (c *ChannelPool) Close() {
+	c.mu.Lock()
+	conns := c.conns
+	c.conns = nil
+	c.factory = nil
+	c.mu.Unlock()
+
+	if conns == nil {
+		return
+	}
+
+	close(conns)
+	for conn := range conns {
+		conn.Close()
+	}
+}
+
+// MaximumCapacity returns the maximum capacity of the pool
+func (c *ChannelPool) MaximumCapacity() int { return cap(c.getConns()) }
+
+// CurrentCapacity returns the current capacity of the pool.
+func (c *ChannelPool) CurrentCapacity() int { return len(c.getConns()) }

pool_test.go → channel_test.go

@@ -23,14 +23,14 @@ func init() {
 }
 
 func TestNew(t *testing.T) {
-	_, err := newPool()
+	_, err := newChannelPool()
 	if err != nil {
 		t.Errorf("New error: %s", err)
 	}
 }
 
 func TestPool_Get(t *testing.T) {
-	p, _ := newPool()
+	p, _ := newChannelPool()
 	defer p.Close()
 
 	_, err := p.Get()
@@ -70,11 +70,11 @@ func TestPool_Get(t *testing.T) {
 }
 
 func TestPool_Put(t *testing.T) {
-	p, _ := newPool()
+	p, _ := newChannelPool()
 	defer p.Close()
 
 	for i := 0; i < MaximumCap; i++ {
-		conn, _ := p.factory()
+		conn, _ := factory()
 		p.Put(conn)
 	}
 
@@ -88,7 +88,7 @@ func TestPool_Put(t *testing.T) {
 		t.Errorf("Put error. A nil conn should be rejected")
 	}
 
-	conn, _ := p.factory()
+	conn, _ := factory()
 	err = p.Put(conn) // try to put into a full pool
 	if err == nil {
 		t.Errorf("Put error. Put into a full pool should return an error")
@@ -97,7 +97,7 @@ func TestPool_Put(t *testing.T) {
 }
 
 func TestPool_MaximumCapacity(t *testing.T) {
-	p, _ := newPool()
+	p, _ := newChannelPool()
 	defer p.Close()
 
 	if p.MaximumCapacity() != MaximumCap {
@@ -107,7 +107,7 @@ func TestPool_MaximumCapacity(t *testing.T) {
 }
 
 func TestPool_UsedCapacity(t *testing.T) {
-	p, _ := newPool()
+	p, _ := newChannelPool()
 	defer p.Close()
 
 	if p.CurrentCapacity() != InitialCap {
@@ -117,17 +117,19 @@ func TestPool_UsedCapacity(t *testing.T) {
 }
 
 func TestPool_Close(t *testing.T) {
-	p, _ := newPool()
-	conn, _ := p.factory() // to be used with put
+	p, _ := newChannelPool()
+	conn, _ := factory() // to be used with put
 
 	// now close it and test all cases we are expecting.
 	p.Close()
 
-	if p.conns != nil {
+	c := p.(*ChannelPool)
+
+	if c.conns != nil {
 		t.Errorf("Close error, conns channel should be nil")
 	}
 
-	if p.factory != nil {
+	if c.factory != nil {
 		t.Errorf("Close error, factory should be nil")
 	}
 
@@ -151,7 +153,7 @@ func TestPool_Close(t *testing.T) {
 }
 
 func TestPoolConcurrent(t *testing.T) {
-	p, _ := newPool()
+	p, _ := newChannelPool()
 	pipe := make(chan net.Conn, 0)
 
 	go func() {
@@ -173,10 +175,10 @@ func TestPoolConcurrent(t *testing.T) {
 }
 
 func TestPoolConcurrent2(t *testing.T) {
-	p, _ := newPool()
+	p, _ := newChannelPool()
 
 	for i := 0; i < MaximumCap; i++ {
-		conn, _ := p.factory()
+		conn, _ := factory()
 		p.Put(conn)
 	}
 
@@ -189,7 +191,9 @@ func TestPoolConcurrent2(t *testing.T) {
 	p.Close()
 }
 
-func newPool() (*Pool, error) { return New(InitialCap, MaximumCap, factory) }
+func newChannelPool() (Pool, error) {
+	return NewChannelPool(InitialCap, MaximumCap, factory)
+}
 
 func simpleTCPServer() {
 	l, err := net.Listen(network, address)

pool.go

@@ -3,9 +3,7 @@ package pool
 
 import (
 	"errors"
-	"fmt"
 	"net"
-	"sync"
 )
 
 var (
@@ -17,120 +15,26 @@ var (
 	ErrPoolFull = errors.New("pool is full")
 )
 
-// Factory is a function to create new connections.
-type Factory func() (net.Conn, error)
+// Pool interface describes a pool implementation.
+type Pool interface {
+	// Get returns a new connection from the pool. After using the connection it
+	// should be put back via the Put() method. If there is no new connection
+	// available in the pool, a new connection will be created via the Factory()
+	// method.
+	Get() (net.Conn, error)
 
-// Pool allows you to use a pool of net.Conn connections.
-type Pool struct {
-	// storage for our net.Conn connections
-	mu    sync.Mutex
-	conns chan net.Conn
+	// Put puts an existing connection into the pool. If the pool is full or
+	// closed, conn is simply closed. A nil conn will be rejected. Putting into a
+	// destroyed or full pool will be counted as an error.
+	Put(conn net.Conn) error
 
-	// net.Conn generator
-	factory Factory
-}
-
-// New returns a new pool with an initial capacity and maximum capacity.
-// Factory is used when initial capacity is greater than zero to fill the
-// pool.
-func New(initialCap, maxCap int, factory Factory) (*Pool, error) {
-	if initialCap <= 0 || maxCap <= 0 || initialCap > maxCap {
-		return nil, errors.New("invalid capacity settings")
-	}
-
-	p := &Pool{
-		conns:   make(chan net.Conn, maxCap),
-		factory: factory,
-	}
-
-	// create initial connections, if something goes wrong,
-	// just close the pool error out.
-	for i := 0; i < initialCap; i++ {
-		conn, err := factory()
-		if err != nil {
-			p.Close()
-			return nil, fmt.Errorf("factory is not able to fill the pool: %s", err)
-		}
-		p.conns <- conn
-	}
-
-	return p, nil
-}
-
-func (p *Pool) getConns() chan net.Conn {
-	p.mu.Lock()
-	conns := p.conns
-	p.mu.Unlock()
-	return conns
-}
+	// Close closes the pool and all its connections. After Close() the
+	// pool is no longer usable.
+	Close()
 
-// Get returns a new connection from the pool. After using the connection it
-// should be put back via the Put() method. If there is no new connection
-// available in the pool, a new connection will be created via the Factory()
-// method.
-func (p *Pool) Get() (net.Conn, error) {
-	conns := p.getConns()
-	if conns == nil {
-		return nil, ErrPoolClosed
-	}
+	// MaximumCapacity returns the maximum capacity of the pool
+	MaximumCapacity() int
 
-	select {
-	case conn := <-conns:
-		if conn == nil {
-			return nil, ErrPoolClosed
-		}
-		return conn, nil
-	default:
-		return p.factory()
-	}
+	// CurrentCapacity returns the current capacity of the pool.
+	CurrentCapacity() int
 }
-
-// Put puts an existing connection into the pool. If the pool is full or
-// closed, conn is simply closed. A nil conn will be rejected. Putting into a
-// destroyed or full pool will be counted as an error.
-func (p *Pool) Put(conn net.Conn) error {
-	if conn == nil {
-		return errors.New("connection is nil. rejecting")
-	}
-
-	p.mu.Lock()
-	defer p.mu.Unlock()
-
-	if p.conns == nil {
-		conn.Close()
-		return ErrPoolClosed
-	}
-
-	select {
-	case p.conns <- conn:
-		return nil
-	default:
-		conn.Close()
-		return ErrPoolFull
-	}
-}
-
-// Close closes the pool and all its connections. After Close() the
-// pool is no longer usable.
-func (p *Pool) Close() {
-	p.mu.Lock()
-	conns := p.conns
-	p.conns = nil
-	p.factory = nil
-	p.mu.Unlock()
-
-	if conns == nil {
-		return
-	}
-
-	close(conns)
-	for conn := range conns {
-		conn.Close()
-	}
-}
-
-// MaximumCapacity returns the maximum capacity of the pool
-func (p *Pool) MaximumCapacity() int { return cap(p.getConns()) }
-
-// CurrentCapacity returns the current capacity of the pool.
-func (p *Pool) CurrentCapacity() int { return len(p.getConns()) }