Refactor Get method to include context argument

Updated the Get method in connpool.go and its usage in tests to include a context argument for better cancellation and timeout handling. Removed the redundant dialContext field from the connection pool struct and added a new test to validate context timeout behavior.

connpool.go

@@ -31,7 +31,7 @@ type Pool interface {
 	// Get returns a new connection from the pool. Closing the connections returns
 	// it back into the Pool. Closing a connection when the Pool is destroyed or
 	// full will be counted as an error.
-	Get() (net.Conn, error)
+	Get(ctx context.Context) (net.Conn, error)
 
 	// Close closes the pool and all its connections. After Close() the pool is
 	// no longer usable.
@@ -50,8 +50,6 @@ type connPool struct {
 
 	// dialCtxFunc represents the actual net.Conn returned by the DialContextFunc.
 	dialCtxFunc DialContextFunc
-	// dialContext is the context used for dialing new network connections within the connection pool.
-	dialContext context.Context
 	// dialNetwork specifies the network type (e.g., "tcp", "udp") used to establish connections in
 	// the connection pool.
 	dialNetwork string
@@ -96,7 +94,8 @@ func (c *PoolConn) MarkUnusable() {
 // new connection available in the pool, a new connection will be created via
 // the corresponding DialContextFunc() method.
 func NewConnPool(ctx context.Context, initialCap, maxCap int, dialCtxFunc DialContextFunc,
-	network, address string) (Pool, error) {
+	network, address string,
+) (Pool, error) {
 	if initialCap < 0 || maxCap <= 0 || initialCap > maxCap {
 		return nil, ErrPoolInvalidCap
 	}
@@ -104,7 +103,6 @@ func NewConnPool(ctx context.Context, initialCap, maxCap int, dialCtxFunc DialCo
 	pool := &connPool{
 		conns:       make(chan net.Conn, maxCap),
 		dialCtxFunc: dialCtxFunc,
-		dialContext: ctx,
 		dialAddress: address,
 		dialNetwork: network,
 	}
@@ -114,10 +112,9 @@ func NewConnPool(ctx context.Context, initialCap, maxCap int, dialCtxFunc DialCo
 		conn, err := dialCtxFunc(ctx, network, address)
 		if err != nil {
 			pool.Close()
-			return nil, fmt.Errorf("dialContextFunc is not able to fill the connection pool: %s", err)
+			return nil, fmt.Errorf("dialContextFunc is not able to fill the connection pool: %w", err)
 		}
 		pool.conns <- conn
-
 	}
 
 	return pool, nil
@@ -126,8 +123,8 @@ func NewConnPool(ctx context.Context, initialCap, maxCap int, dialCtxFunc DialCo
 // Get satisfies the Get() method of the Pool inteface. If there is no new
 // connection available in the Pool, a new connection will be created via the
 // DialContextFunc() method.
-func (p *connPool) Get() (net.Conn, error) {
+func (p *connPool) Get(ctx context.Context) (net.Conn, error) {
-	ctx, conns, dialCtxFunc := p.getConnsAndDialContext()
+	conns, dialCtxFunc := p.getConnsAndDialContext()
 	if conns == nil {
 		return nil, ErrClosed
 	}
@@ -136,7 +133,7 @@ func (p *connPool) Get() (net.Conn, error) {
 	// connections back to the pool
 	select {
 	case <-ctx.Done():
-		return nil, ctx.Err()
+		return nil, fmt.Errorf("failed to get connection: %w", ctx.Err())
 	case conn := <-conns:
 		if conn == nil {
 			return nil, ErrClosed
@@ -145,7 +142,7 @@ func (p *connPool) Get() (net.Conn, error) {
 	default:
 		conn, err := dialCtxFunc(ctx, p.dialNetwork, p.dialAddress)
 		if err != nil {
-			return nil, err
+			return nil, fmt.Errorf("dialContextFunc failed: %w", err)
 		}
 		return p.wrapConn(conn), nil
 	}
@@ -158,7 +155,6 @@ func (p *connPool) Close() {
 	conns := p.conns
 	p.conns = nil
 	p.dialCtxFunc = nil
-	p.dialContext = nil
 	p.dialAddress = ""
 	p.dialNetwork = ""
 	p.mutex.Unlock()
@@ -175,19 +171,18 @@ func (p *connPool) Close() {
 
 // Size returns the current number of connections in the connection pool.
 func (p *connPool) Size() int {
-	_, conns, _ := p.getConnsAndDialContext()
+	conns, _ := p.getConnsAndDialContext()
 	return len(conns)
 }
 
 // getConnsAndDialContext returns the connection channel and the DialContext function for the
 // connection pool.
-func (p *connPool) getConnsAndDialContext() (context.Context, chan net.Conn, DialContextFunc) {
+func (p *connPool) getConnsAndDialContext() (chan net.Conn, DialContextFunc) {
 	p.mutex.RLock()
 	conns := p.conns
 	dialCtxFunc := p.dialCtxFunc
-	ctx := p.dialContext
 	p.mutex.RUnlock()
-	return ctx, conns, dialCtxFunc
+	return conns, dialCtxFunc
 }
 
 // put puts a passed connection back into the pool. If the pool is full or closed,

connpool_test.go

@@ -39,7 +39,7 @@ func TestNewConnPool(t *testing.T) {
 	if pool.Size() != 5 {
 		t.Errorf("expected 5 connections, got %d", pool.Size())
 	}
-	conn, err := pool.Get()
+	conn, err := pool.Get(context.Background())
 	if err != nil {
 		t.Errorf("failed to get connection: %s", err)
 	}
@@ -68,7 +68,7 @@ func TestConnPool_Get_Type(t *testing.T) {
 	}
 	defer pool.Close()
 
-	conn, err := pool.Get()
+	conn, err := pool.Get(context.Background())
 	if err != nil {
 		t.Errorf("failed to get new connection from pool: %s", err)
 		return
@@ -101,7 +101,7 @@ func TestConnPool_Get(t *testing.T) {
 	p, _ := newConnPool(serverPort)
 	defer p.Close()
 
-	conn, err := p.Get()
+	conn, err := p.Get(context.Background())
 	if err != nil {
 		t.Errorf("failed to get new connection from pool: %s", err)
 		return
@@ -119,7 +119,7 @@ func TestConnPool_Get(t *testing.T) {
 		wg.Add(1)
 		go func() {
 			defer wg.Done()
-			wgconn, err := p.Get()
+			wgconn, err := p.Get(context.Background())
 			if err != nil {
 				t.Errorf("failed to get new connection from pool: %s", err)
 			}
@@ -134,7 +134,7 @@ func TestConnPool_Get(t *testing.T) {
 		t.Errorf("Get error. Expecting 0, got %d", p.Size())
 	}
 
-	conn, err = p.Get()
+	conn, err = p.Get(context.Background())
 	if err != nil {
 		t.Errorf("failed to get new connection from pool: %s", err)
 	}
@@ -168,7 +168,7 @@ func TestPoolConn_Close(t *testing.T) {
 
 	conns := make([]net.Conn, 30)
 	for i := 0; i < 30; i++ {
-		conn, _ := p.Get()
+		conn, _ := p.Get(context.Background())
 		if _, err = conn.Write([]byte("EHLO test.localhost.localdomain\r\nQUIT\r\n")); err != nil {
 			t.Errorf("failed to write quit command to first connection: %s", err)
 		}
@@ -184,7 +184,7 @@ func TestPoolConn_Close(t *testing.T) {
 		t.Errorf("failed to return all connections to pool. Expected pool size: 30, got %d", p.Size())
 	}
 
-	conn, err := p.Get()
+	conn, err := p.Get(context.Background())
 	if err != nil {
 		t.Errorf("failed to get new connection from pool: %s", err)
 	}
@@ -218,7 +218,7 @@ func TestPoolConn_MarkUnusable(t *testing.T) {
 	pool, _ := newConnPool(serverPort)
 	defer pool.Close()
 
-	conn, err := pool.Get()
+	conn, err := pool.Get(context.Background())
 	if err != nil {
 		t.Errorf("failed to get new connection from pool: %s", err)
 	}
@@ -227,7 +227,7 @@ func TestPoolConn_MarkUnusable(t *testing.T) {
 	}
 
 	poolSize := pool.Size()
-	conn, err = pool.Get()
+	conn, err = pool.Get(context.Background())
 	if err != nil {
 		t.Errorf("failed to get new connection from pool: %s", err)
 	}
@@ -238,7 +238,7 @@ func TestPoolConn_MarkUnusable(t *testing.T) {
 		t.Errorf("pool size is expected to be equal to initial size")
 	}
 
-	conn, err = pool.Get()
+	conn, err = pool.Get(context.Background())
 	if err != nil {
 		t.Errorf("failed to get new connection from pool: %s", err)
 	}
@@ -283,9 +283,6 @@ func TestConnPool_Close(t *testing.T) {
 	if castPool.dialCtxFunc != nil {
 		t.Error("closing pool failed: dialCtxFunc should be nil")
 	}
-	if castPool.dialContext != nil {
-		t.Error("closing pool failed: dialContext should be nil")
-	}
 	if castPool.dialAddress != "" {
 		t.Error("closing pool failed: dialAddress should be empty")
 	}
@@ -293,7 +290,7 @@ func TestConnPool_Close(t *testing.T) {
 		t.Error("closing pool failed: dialNetwork should be empty")
 	}
 
-	conn, err := pool.Get()
+	conn, err := pool.Get(context.Background())
 	if err == nil {
 		t.Errorf("closing pool failed: getting new connection should return an error")
 	}
@@ -332,7 +329,7 @@ func TestConnPool_Concurrency(t *testing.T) {
 		getWg.Add(1)
 		closeWg.Add(1)
 		go func() {
-			conn, err := pool.Get()
+			conn, err := pool.Get(context.Background())
 			if err != nil {
 				t.Errorf("failed to get new connection from pool: %s", err)
 			}
@@ -355,6 +352,70 @@ func TestConnPool_Concurrency(t *testing.T) {
 	}
 }
 
+func TestConnPool_GetContextTimeout(t *testing.T) {
+	ctx, cancel := context.WithCancel(context.Background())
+	defer cancel()
+
+	serverPort := TestServerPortBase + 17
+	featureSet := "250-AUTH PLAIN\r\n250-8BITMIME\r\n250-DSN\r\n250 SMTPUTF8"
+	go func() {
+		if err := simpleSMTPServer(ctx, featureSet, true, serverPort); err != nil {
+			t.Errorf("failed to start test server: %s", err)
+			return
+		}
+	}()
+	time.Sleep(time.Millisecond * 300)
+
+	p, err := newConnPool(serverPort)
+	if err != nil {
+		t.Errorf("failed to create connection pool: %s", err)
+	}
+	defer p.Close()
+
+	connCtx, connCancel := context.WithCancel(context.Background())
+	defer connCancel()
+
+	conn, err := p.Get(connCtx)
+	if err != nil {
+		t.Errorf("failed to get new connection from pool: %s", err)
+		return
+	}
+	if _, err = conn.Write([]byte("EHLO test.localhost.localdomain\r\nQUIT\r\n")); err != nil {
+		t.Errorf("failed to write quit command to first connection: %s", err)
+	}
+
+	if p.Size() != 4 {
+		t.Errorf("getting new connection from pool failed. Expected pool size: 4, got %d", p.Size())
+	}
+
+	var wg sync.WaitGroup
+	for i := 0; i < 4; i++ {
+		wg.Add(1)
+		go func() {
+			defer wg.Done()
+			wgconn, err := p.Get(connCtx)
+			if err != nil {
+				t.Errorf("failed to get new connection from pool: %s", err)
+			}
+			if _, err = wgconn.Write([]byte("EHLO test.localhost.localdomain\r\nQUIT\r\n")); err != nil {
+				t.Errorf("failed to write quit command to first connection: %s", err)
+			}
+		}()
+	}
+	wg.Wait()
+
+	if p.Size() != 0 {
+		t.Errorf("Get error. Expecting 0, got %d", p.Size())
+	}
+
+	connCancel()
+	_, err = p.Get(connCtx)
+	if err == nil {
+		t.Errorf("getting new connection on canceled context should fail, but didn't")
+	}
+	p.Close()
+}
+
 func newConnPool(port int) (Pool, error) {
 	netDialer := net.Dialer{}
 	return NewConnPool(context.Background(), 5, 30, netDialer.DialContext, "tcp",