From 35932b7961a8212784cef078564c5394aff61bb6 Mon Sep 17 00:00:00 2001
From: Vladimir Mihailenco <vladimir.webdev@gmail.com>
Date: Sat, 8 Jun 2019 15:36:00 +0300
Subject: [PATCH] Check context.Done while waiting for a connection

---
 internal/pool/pool.go        | 25 +++++++++++++++++--------
 internal/pool/pool_single.go |  2 +-
 internal/pool/pool_sticky.go |  4 ++--
 3 files changed, 20 insertions(+), 11 deletions(-)

diff --git a/internal/pool/pool.go b/internal/pool/pool.go
index fa6855c..013e29b 100644
--- a/internal/pool/pool.go
+++ b/internal/pool/pool.go
@@ -130,8 +130,8 @@ func (p *ConnPool) NewConn() (*Conn, error) {
 	return p._NewConn(nil, false)
 }
 
-func (p *ConnPool) _NewConn(c context.Context, pooled bool) (*Conn, error) {
-	cn, err := p.newConn(c, pooled)
+func (p *ConnPool) _NewConn(ctx context.Context, pooled bool) (*Conn, error) {
+	cn, err := p.newConn(ctx, pooled)
 	if err != nil {
 		return nil, err
 	}
@@ -149,7 +149,7 @@ func (p *ConnPool) _NewConn(c context.Context, pooled bool) (*Conn, error) {
 	return cn, nil
 }
 
-func (p *ConnPool) newConn(c context.Context, pooled bool) (*Conn, error) {
+func (p *ConnPool) newConn(ctx context.Context, pooled bool) (*Conn, error) {
 	if p.closed() {
 		return nil, ErrClosed
 	}
@@ -158,7 +158,7 @@ func (p *ConnPool) newConn(c context.Context, pooled bool) (*Conn, error) {
 		return nil, p.getLastDialError()
 	}
 
-	netConn, err := p.opt.Dialer(c)
+	netConn, err := p.opt.Dialer(ctx)
 	if err != nil {
 		p.setLastDialError(err)
 		if atomic.AddUint32(&p.dialErrorsNum, 1) == uint32(p.opt.PoolSize) {
@@ -205,12 +205,12 @@ func (p *ConnPool) getLastDialError() error {
 }
 
 // Get returns existed connection from the pool or creates a new one.
-func (p *ConnPool) Get(c context.Context) (*Conn, error) {
+func (p *ConnPool) Get(ctx context.Context) (*Conn, error) {
 	if p.closed() {
 		return nil, ErrClosed
 	}
 
-	err := p.waitTurn()
+	err := p.waitTurn(ctx)
 	if err != nil {
 		return nil, err
 	}
@@ -235,7 +235,7 @@ func (p *ConnPool) Get(c context.Context) (*Conn, error) {
 
 	atomic.AddUint32(&p.stats.Misses, 1)
 
-	newcn, err := p._NewConn(c, true)
+	newcn, err := p._NewConn(ctx, true)
 	if err != nil {
 		p.freeTurn()
 		return nil, err
@@ -248,8 +248,15 @@ func (p *ConnPool) getTurn() {
 	p.queue <- struct{}{}
 }
 
-func (p *ConnPool) waitTurn() error {
+func (p *ConnPool) waitTurn(ctx context.Context) error {
+	var done <-chan struct{}
+	if ctx != nil {
+		done = ctx.Done()
+	}
+
 	select {
+	case <-done:
+		return ctx.Err()
 	case p.queue <- struct{}{}:
 		return nil
 	default:
@@ -257,6 +264,8 @@ func (p *ConnPool) waitTurn() error {
 		timer.Reset(p.opt.PoolTimeout)
 
 		select {
+		case <-done:
+			return ctx.Err()
 		case p.queue <- struct{}{}:
 			if !timer.Stop() {
 				<-timer.C
diff --git a/internal/pool/pool_single.go b/internal/pool/pool_single.go
index 6112d8f..778b124 100644
--- a/internal/pool/pool_single.go
+++ b/internal/pool/pool_single.go
@@ -22,7 +22,7 @@ func (p *SingleConnPool) CloseConn(*Conn) error {
 	panic("not implemented")
 }
 
-func (p *SingleConnPool) Get(c context.Context) (*Conn, error) {
+func (p *SingleConnPool) Get(ctx context.Context) (*Conn, error) {
 	return p.cn, nil
 }
 
diff --git a/internal/pool/pool_sticky.go b/internal/pool/pool_sticky.go
index 1e632ec..174dc9c 100644
--- a/internal/pool/pool_sticky.go
+++ b/internal/pool/pool_sticky.go
@@ -31,7 +31,7 @@ func (p *StickyConnPool) CloseConn(*Conn) error {
 	panic("not implemented")
 }
 
-func (p *StickyConnPool) Get(c context.Context) (*Conn, error) {
+func (p *StickyConnPool) Get(ctx context.Context) (*Conn, error) {
 	p.mu.Lock()
 	defer p.mu.Unlock()
 
@@ -42,7 +42,7 @@ func (p *StickyConnPool) Get(c context.Context) (*Conn, error) {
 		return p.cn, nil
 	}
 
-	cn, err := p.pool.Get(c)
+	cn, err := p.pool.Get(ctx)
 	if err != nil {
 		return nil, err
 	}