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// +build go1.8
package pq
import (
"context"
"database/sql/driver"
"errors"
"io"
"io/ioutil"
)
// Implement the "QueryerContext" interface
func (cn *conn) QueryContext(ctx context.Context, query string, args []driver.NamedValue) (driver.Rows, error) {
list := make([]driver.Value, len(args))
for i, nv := range args {
list[i] = nv.Value
}
finish := cn.watchCancel(ctx)
r, err := cn.query(query, list)
if err != nil {
return nil, err
}
r.finish = finish
return r, nil
}
// Implement the "ExecerContext" interface
func (cn *conn) ExecContext(ctx context.Context, query string, args []driver.NamedValue) (driver.Result, error) {
list := make([]driver.Value, len(args))
for i, nv := range args {
list[i] = nv.Value
}
if finish := cn.watchCancel(ctx); finish != nil {
defer finish()
}
return cn.Exec(query, list)
}
// Implement the "ConnBeginTx" interface
func (cn *conn) BeginTx(ctx context.Context, opts driver.TxOptions) (driver.Tx, error) {
if opts.Isolation != 0 {
return nil, errors.New("isolation levels not supported")
}
if opts.ReadOnly {
return nil, errors.New("read-only transactions not supported")
}
tx, err := cn.Begin()
if err != nil {
return nil, err
}
cn.txnFinish = cn.watchCancel(ctx)
return tx, nil
}
func (cn *conn) watchCancel(ctx context.Context) func() {
if done := ctx.Done(); done != nil {
finished := make(chan struct{})
go func() {
select {
case <-done:
_ = cn.cancel()
finished <- struct{}{}
case <-finished:
}
}()
return func() {
select {
case <-finished:
case finished <- struct{}{}:
}
}
}
return nil
}
func (cn *conn) cancel() error {
c, err := dial(cn.dialer, cn.opts)
if err != nil {
return err
}
defer c.Close()
{
can := conn{
c: c,
}
can.ssl(cn.opts)
w := can.writeBuf(0)
w.int32(80877102) // cancel request code
w.int32(cn.processID)
w.int32(cn.secretKey)
if err := can.sendStartupPacket(w); err != nil {
return err
}
}
// Read until EOF to ensure that the server received the cancel.
{
_, err := io.Copy(ioutil.Discard, c)
return err
}
}
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