Add ConnPool context methods

conn.go

@@ -1051,9 +1051,12 @@ func (c *Conn) processContextFreeMsg(t byte, r *msgReader) (err error) {
 }
 
 func (c *Conn) rxMsg() (t byte, r *msgReader, err error) {
+	c.closingLock.Lock()
 	if !c.alive {
+		c.closingLock.Unlock()
 		return 0, nil, ErrDeadConn
 	}
+	c.closingLock.Unlock()
 
 	t, err = c.mr.rxMsg()
 	if err != nil {

conn_pool.go

@@ -2,6 +2,7 @@ package pgx
 
 import (
 	"errors"
+	"golang.org/x/net/context"
 	"sync"
 	"time"
 )
@@ -357,6 +358,16 @@ func (p *ConnPool) Exec(sql string, arguments ...interface{}) (commandTag Comman
 	return c.Exec(sql, arguments...)
 }
 
+func (p *ConnPool) ExecContext(ctx context.Context, sql string, arguments ...interface{}) (commandTag CommandTag, err error) {
+	var c *Conn
+	if c, err = p.Acquire(); err != nil {
+		return
+	}
+	defer p.Release(c)
+
+	return c.ExecContext(ctx, sql, arguments...)
+}
+
 // Query acquires a connection and delegates the call to that connection. When
 // *Rows are closed, the connection is released automatically.
 func (p *ConnPool) Query(sql string, args ...interface{}) (*Rows, error) {
@@ -377,6 +388,24 @@ func (p *ConnPool) Query(sql string, args ...interface{}) (*Rows, error) {
 	return rows, nil
 }
 
+func (p *ConnPool) QueryContext(ctx context.Context, sql string, args ...interface{}) (*Rows, error) {
+	c, err := p.Acquire()
+	if err != nil {
+		// Because checking for errors can be deferred to the *Rows, build one with the error
+		return &Rows{closed: true, err: err}, err
+	}
+
+	rows, err := c.QueryContext(ctx, sql, args...)
+	if err != nil {
+		p.Release(c)
+		return rows, err
+	}
+
+	rows.AfterClose(p.rowsAfterClose)
+
+	return rows, nil
+}
+
 // QueryRow acquires a connection and delegates the call to that connection. The
 // connection is released automatically after Scan is called on the returned
 // *Row.
@@ -385,6 +414,11 @@ func (p *ConnPool) QueryRow(sql string, args ...interface{}) *Row {
 	return (*Row)(rows)
 }
 
+func (p *ConnPool) QueryRowContext(ctx context.Context, sql string, args ...interface{}) *Row {
+	rows, _ := p.QueryContext(ctx, sql, args...)
+	return (*Row)(rows)
+}
+
 // Begin acquires a connection and begins a transaction on it. When the
 // transaction is closed the connection will be automatically released.
 func (p *ConnPool) Begin() (*Tx, error) {

context-todo.txt

@@ -0,0 +1,12 @@
+Add more testing
+- stress test style
+- pgmock
+
+Add documentation
+
+Add PrepareContext
+Add context methods to ConnPool
+Add context methods to Tx
+Add context support database/sql
+
+Benchmark - possibly cache done channel on Conn

query.go

@@ -51,8 +51,9 @@ type Rows struct {
 	unlockConn bool
 	closed     bool
 
-	ctx      context.Context
-	doneChan chan struct{}
+	ctx        context.Context
+	doneChan   chan struct{}
+	closedChan chan bool
 }
 
 func (rows *Rows) FieldDescriptions() []FieldDescription {
@@ -127,7 +128,7 @@ func (rows *Rows) Close() {
 
 	if rows.ctx != nil {
 		select {
-		case <-rows.ctx.Done():
+		case <-rows.closedChan:
 			rows.err = rows.ctx.Err()
 		case rows.doneChan <- struct{}{}:
 		}
@@ -508,12 +509,14 @@ 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:
 		}
 	}()
@@ -522,7 +525,7 @@ func (c *Conn) QueryContext(ctx context.Context, sql string, args ...interface{}
 
 	if err != nil {
 		select {
-		case <-ctx.Done():
+		case <-closedChan:
 			return rows, ctx.Err()
 		case doneChan <- struct{}{}:
 			return rows, err
@@ -531,6 +534,7 @@ func (c *Conn) QueryContext(ctx context.Context, sql string, args ...interface{}
 
 	rows.ctx = ctx
 	rows.doneChan = doneChan
+	rows.closedChan = closedChan
 
 	return rows, nil
 }

stress_test.go

@@ -3,6 +3,7 @@ package pgx_test
 import (
 	"errors"
 	"fmt"
+	"golang.org/x/net/context"
 	"math/rand"
 	"testing"
 	"time"
@@ -44,6 +45,8 @@ func TestStressConnPool(t *testing.T) {
 		{"listenAndPoolUnlistens", listenAndPoolUnlistens},
 		{"reset", func(p *pgx.ConnPool, n int) error { p.Reset(); return nil }},
 		{"poolPrepareUseAndDeallocate", poolPrepareUseAndDeallocate},
+		{"canceledQueryContext", canceledQueryContext},
+		{"canceledExecContext", canceledExecContext},
 	}
 
 	var timer *time.Timer
@@ -344,3 +347,43 @@ func txMultipleQueries(pool *pgx.ConnPool, actionNum int) error {
 
 	return tx.Commit()
 }
+
+func canceledQueryContext(pool *pgx.ConnPool, actionNum int) error {
+	ctx, cancelFunc := context.WithCancel(context.Background())
+	go func() {
+		time.Sleep(time.Duration(rand.Intn(50)) * time.Millisecond)
+		cancelFunc()
+	}()
+
+	rows, err := pool.QueryContext(ctx, "select pg_sleep(5)")
+	if err == context.Canceled {
+		return nil
+	} else if err != nil {
+		return fmt.Errorf("canceledQueryContext: Only allowed error is context.Canceled, got %v", err)
+	}
+
+	for rows.Next() {
+		return errors.New("canceledQueryContext: should never receive row")
+	}
+
+	if rows.Err() != context.Canceled {
+		return fmt.Errorf("canceledQueryContext: Expected context.Canceled error, got %v", rows.Err())
+	}
+
+	return nil
+}
+
+func canceledExecContext(pool *pgx.ConnPool, actionNum int) error {
+	ctx, cancelFunc := context.WithCancel(context.Background())
+	go func() {
+		time.Sleep(time.Duration(rand.Intn(50)) * time.Millisecond)
+		cancelFunc()
+	}()
+
+	_, err := pool.ExecContext(ctx, "select pg_sleep(5)")
+	if err != context.Canceled {
+		return fmt.Errorf("canceledExecContext: Expected context.Canceled error, got %v", err)
+	}
+
+	return nil
+}