README
¶
Makes a standard os.File a "reopenable writer" and allows SIGHUP signals to reopen log files, as needed by logrotated. This is inspired by the C/Posix freopen
The simple version reopen.NewFileWriter does unbuffered writing. A
call to .Reopen closes the existing file handle, and then re-opens
it using the original filename.
The more advanced version reopen.NewBufferedFileWriter buffers input
and flushes when the internal buffer is full (with care) or if 30 seconds has
elapsed.
There is also reopen.Stderr and reopen.Stdout which implements the reopen.Reopener interface (and does nothing on a reopen call).
reopen.Discard wraps ioutil.Discard
Samples are in example1 and example2. The run.sh scripts are a
dumb test where the file is rotated underneath the server, and nothing
is lost. This is not the most robust test but gives you an idea of how it works.
Here's some sample code.
package main
/* Simple logrotate logger
*/
import (
"fmt"
"log"
"net/http"
"os"
"os/signal"
"syscall"
"github.com/client9/reopen"
)
func main() {
// setup logger to write to our new *reopenable* log file
f, err := reopen.NewFileWriter("/tmp/example.log")
if err != nil {
log.Fatalf("Unable to set output log: %s", err)
}
log.SetOutput(f)
// Handle SIGHUP
//
// channel is number of signals needed to catch (more or less)
// we only are working with one here, SIGHUP
sighup := make(chan os.Signal, 1)
signal.Notify(sighup, syscall.SIGHUP)
go func() {
for {
<-sighup
fmt.Println("Got a sighup")
f.Reopen()
}
}()
// dumb http server that just prints and logs the path
http.HandleFunc("/", func(w http.ResponseWriter, r *http.Request) {
log.Printf("%s", r.URL.Path)
fmt.Fprintf(w, "%s\n", r.URL.Path)
})
log.Fatal(http.ListenAndServe("127.0.0.1:8123", nil))
}
Documentation
¶
Index ¶
Constants ¶
This section is empty.
Variables ¶
var ( Stdout = NopWriter(os.Stdout) Stderr = NopWriter(os.Stderr) Discard = NopWriter(ioutil.Discard) )
Reopenable versions of os.Stdout, os.Stderr, /dev/null (reopen does nothing)
Functions ¶
This section is empty.
Types ¶
type BufferedFileWriter ¶
type BufferedFileWriter struct {
// contains filtered or unexported fields
}
BufferedFileWriter is buffer writer than can be reopned
func NewBufferedFileWriter ¶
func NewBufferedFileWriter(w *FileWriter) *BufferedFileWriter
NewBufferedFileWriter opens a buffered file that is periodically
flushed.
func NewBufferedFileWriterSize ¶
func NewBufferedFileWriterSize(w *FileWriter, size int, flush time.Duration) *BufferedFileWriter
NewBufferedFileWriterSize opens a buffered file with the given size that is periodically
flushed on the given interval.
func (*BufferedFileWriter) Close ¶
func (bw *BufferedFileWriter) Close() error
Close flushes the internal buffer and closes the destination file
func (*BufferedFileWriter) Reopen ¶
func (bw *BufferedFileWriter) Reopen() error
Reopen implement Reopener
type FileWriter ¶
type FileWriter struct {
// contains filtered or unexported fields
}
FileWriter that can also be reopened
func NewFileWriter ¶
func NewFileWriter(name string) (*FileWriter, error)
NewFileWriter opens a file for appending and writing and can be reopened. it is a ReopenWriteCloser...
func NewFileWriterMode ¶
func NewFileWriterMode(name string, mode os.FileMode) (*FileWriter, error)
NewFileWriterMode opens a Reopener file with a specific permission
func (*FileWriter) Close ¶
func (f *FileWriter) Close() error
Close calls the underlyding File.Close()
type Reopener ¶
type Reopener interface {
Reopen() error
}
Reopener interface defines something that can be reopened
type WriteCloser ¶
type WriteCloser interface {
Reopener
io.WriteCloser
}
WriteCloser is a io.WriteCloser that can also be reopened
func NopWriter ¶
func NopWriter(w io.Writer) WriteCloser
NopWriter turns a normal writer into a ReopenWriter
by doing a NOP on Reopen. See https://en.wikipedia.org/wiki/NOP
type Writer ¶
Writer is a writer that also can be reopened
func MultiWriter ¶
MultiWriter creates a writer that duplicates its writes to all the provided writers, similar to the Unix tee(1) command.
Also allow reopen
Source Files
Directories