README
¶
contextio - Context-aware I/O streams for Go
Author: @dolmen (Olivier Mengué).
Example
go test -run ExampleWriter
func main() {
// interrupt context after 500ms
ctx, cancel := context.WithTimeout(context.Background(), 500*time.Millisecond)
defer cancel()
// interrupt context with SIGTERM (CTRL+C)
sigs := make(chan os.Signal, 1)
signal.Notify(sigs, os.Interrupt)
go func() {
<-sigs
cancel()
}()
f, err := os.OpenFile(os.DevNull, os.O_WRONLY, 0)
if err != nil {
log.Fatal(err)
}
defer f.Close()
// Writer that fails when context is canceled
out := contextio.NewWriter(ctx, f)
// Infinite loop. Will only be interrupted once write fails.
for {
if _, err := out.Write([]byte{'a', 'b', 'c'}); err != nil {
fmt.Println("Err:", err)
break
}
}
fmt.Println("Closing.")
}
See Also
- github.com/jbenet/go-context/io Context-aware reader and writer
- github.com/northbright/ctx/ctxcopy Context-aware io.Copy
- gitlab.com/streamy/concon Context-aware net.Conn
Documentation
¶
Overview ¶
Package contextio provides io.Writer and io.Reader that stop accepting/providing data when an attached context is canceled.
Example (Copy) ¶
package main
import (
"context"
"fmt"
"io"
"log"
"os"
"os/signal"
"time"
"github.com/dolmen-go/contextio"
)
func main() {
// interrupt context after 500ms
ctx, cancel := context.WithTimeout(context.Background(), 500*time.Millisecond)
defer cancel()
// interrupt context with SIGTERM (CTRL+C)
sigs := make(chan os.Signal, 1)
signal.Notify(sigs, os.Interrupt)
go func() {
<-sigs
cancel()
}()
fIn, err := os.Open("/dev/zero")
if err != nil {
log.Fatal(err)
}
defer fIn.Close()
fOut, err := os.OpenFile(os.DevNull, os.O_WRONLY, 0)
if err != nil {
log.Fatal(err)
}
defer fOut.Close()
// Reader that fails when context is canceled
in := contextio.NewReader(ctx, fIn)
// Writer that fails when context is canceled
out := contextio.NewWriter(ctx, fOut)
n, err := io.Copy(out, in)
log.Println(n, "bytes copied.")
if err != nil {
fmt.Println("Err:", err)
}
fmt.Println("Closing.")
}
Output: Err: context deadline exceeded Closing.
Index ¶
Examples ¶
Constants ¶
This section is empty.
Variables ¶
This section is empty.
Functions ¶
func NewCloser ¶
NewCloser wraps an io.Reader to handle context cancellation.
Context state is checked BEFORE any Close.
func NewReader ¶
NewReader wraps an io.Reader to handle context cancellation.
Context state is checked BEFORE every Read.
func NewWriter ¶
NewWriter wraps an io.Writer to handle context cancellation.
Context state is checked BEFORE every Write.
The returned Writer also implements io.ReaderFrom to allow io.Copy to select the best strategy while still checking the context state before every chunk transfer.
Example ¶
package main
import (
"context"
"fmt"
"log"
"os"
"os/signal"
"time"
"github.com/dolmen-go/contextio"
)
func main() {
// interrupt context after 500ms
ctx, cancel := context.WithTimeout(context.Background(), 500*time.Millisecond)
defer cancel()
// interrupt context with SIGTERM (CTRL+C)
sigs := make(chan os.Signal, 1)
signal.Notify(sigs, os.Interrupt)
go func() {
<-sigs
cancel()
}()
f, err := os.OpenFile(os.DevNull, os.O_WRONLY, 0)
if err != nil {
log.Fatal(err)
}
defer f.Close()
// Writer that fails when context is canceled
out := contextio.NewWriter(ctx, f)
// Infinite loop. Will only be interrupted once write fails.
for {
if _, err := out.Write([]byte{'a', 'b', 'c'}); err != nil {
fmt.Println("Err:", err)
break
}
}
fmt.Println("Closing.")
}
Output: Err: context deadline exceeded Closing.
Types ¶
This section is empty.
Source Files
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