From 004c18e5a21c7837cb6dc578f22471115b29fdc8 Mon Sep 17 00:00:00 2001
From: Jack Christensen <jack@jackchristensen.com>
Date: Tue, 7 Feb 2017 20:35:37 -0600
Subject: [PATCH] Begin extracting context handling

---
 conn.go  | 53 +++++++++++++++++++++++------------------------------
 query.go | 27 ++++++---------------------
 2 files changed, 29 insertions(+), 51 deletions(-)

diff --git a/conn.go b/conn.go
index b8131716..453f1a51 100644
--- a/conn.go
+++ b/conn.go
@@ -88,6 +88,10 @@ type Conn struct {
 	closingLock  sync.Mutex
 	alive        bool
 	causeOfDeath error
+
+	// context support
+	doneChan   chan struct{}
+	closedChan chan struct{}
 }
 
 // PreparedStatement is a description of a prepared statement
@@ -257,6 +261,8 @@ func (c *Conn) connect(config ConnConfig, network, address string, tlsConfig *tl
 	c.channels = make(map[string]struct{})
 	c.alive = true
 	c.lastActivityTime = time.Now()
+	c.doneChan = make(chan struct{})
+	c.closedChan = make(chan struct{})
 
 	if tlsConfig != nil {
 		if c.shouldLog(LogLevelDebug) {
@@ -619,8 +625,7 @@ func (c *Conn) Prepare(name, sql string) (ps *PreparedStatement, err error) {
 // name and sql arguments. This allows a code path to PrepareEx and Query/Exec without
 // concern for if the statement has already been prepared.
 func (c *Conn) PrepareEx(name, sql string, opts *PrepareExOptions) (ps *PreparedStatement, err error) {
-	return c.PrepareExContext(context.Background(), name, sql, opts)
-
+	return c.prepareEx(name, sql, opts)
 }
 
 func (c *Conn) PrepareExContext(ctx context.Context, name, sql string, opts *PrepareExOptions) (ps *PreparedStatement, err error) {
@@ -630,25 +635,14 @@ func (c *Conn) PrepareExContext(ctx context.Context, name, sql string, opts *Pre
 	default:
 	}
 
-	doneChan := make(chan struct{})
-	closedChan := make(chan struct{})
-
-	go func() {
-		select {
-		case <-ctx.Done():
-			c.cancelQuery()
-			c.Close()
-			closedChan <- struct{}{}
-		case <-doneChan:
-		}
-	}()
+	go c.contextHandler(ctx)
 
 	ps, err = c.prepareEx(name, sql, opts)
 
 	select {
-	case <-closedChan:
+	case <-c.closedChan:
 		return nil, ctx.Err()
-	case doneChan <- struct{}{}:
+	case c.doneChan <- struct{}{}:
 		return ps, err
 	}
 }
@@ -1383,25 +1377,24 @@ func (c *Conn) ExecContext(ctx context.Context, sql string, arguments ...interfa
 	default:
 	}
 
-	doneChan := make(chan struct{})
-	closedChan := make(chan struct{})
-
-	go func() {
-		select {
-		case <-ctx.Done():
-			c.cancelQuery()
-			c.Close()
-			closedChan <- struct{}{}
-		case <-doneChan:
-		}
-	}()
+	go c.contextHandler(ctx)
 
 	commandTag, err = c.Exec(sql, arguments...)
 
 	select {
-	case <-closedChan:
+	case <-c.closedChan:
 		return "", ctx.Err()
-	case doneChan <- struct{}{}:
+	case c.doneChan <- struct{}{}:
 		return commandTag, err
 	}
 }
+
+func (c *Conn) contextHandler(ctx context.Context) {
+	select {
+	case <-ctx.Done():
+		c.cancelQuery()
+		c.Close()
+		c.closedChan <- struct{}{}
+	case <-c.doneChan:
+	}
+}
diff --git a/query.go b/query.go
index 3ded881d..daf1b354 100644
--- a/query.go
+++ b/query.go
@@ -51,9 +51,7 @@ type Rows struct {
 	unlockConn bool
 	closed     bool
 
-	ctx        context.Context
-	doneChan   chan struct{}
-	closedChan chan bool
+	ctx context.Context
 }
 
 func (rows *Rows) FieldDescriptions() []FieldDescription {
@@ -128,9 +126,9 @@ func (rows *Rows) Close() {
 
 	if rows.ctx != nil {
 		select {
-		case <-rows.closedChan:
+		case <-rows.conn.closedChan:
 			rows.err = rows.ctx.Err()
-		case rows.doneChan <- struct{}{}:
+		case rows.conn.doneChan <- struct{}{}:
 		}
 	}
 
@@ -508,33 +506,20 @@ func (c *Conn) QueryRow(sql string, args ...interface{}) *Row {
 }
 
 func (c *Conn) QueryContext(ctx context.Context, sql string, args ...interface{}) (*Rows, error) {
-	doneChan := make(chan struct{})
-	closedChan := make(chan bool)
-
-	go func() {
-		select {
-		case <-ctx.Done():
-			c.cancelQuery()
-			c.Close()
-			closedChan <- true
-		case <-doneChan:
-		}
-	}()
+	go c.contextHandler(ctx)
 
 	rows, err := c.Query(sql, args...)
 
 	if err != nil {
 		select {
-		case <-closedChan:
+		case <-c.closedChan:
 			return rows, ctx.Err()
-		case doneChan <- struct{}{}:
+		case c.doneChan <- struct{}{}:
 			return rows, err
 		}
 	}
 
 	rows.ctx = ctx
-	rows.doneChan = doneChan
-	rows.closedChan = closedChan
 
 	return rows, nil
 }