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189 lines
3.9 KiB
189 lines
3.9 KiB
package autofile
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import (
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"os"
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"os/signal"
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"sync"
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"syscall"
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"time"
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cmn "github.com/tendermint/tendermint/libs/common"
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"github.com/tendermint/tendermint/libs/errors"
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)
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/* AutoFile usage
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// Create/Append to ./autofile_test
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af, err := OpenAutoFile("autofile_test")
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if err != nil {
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panic(err)
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}
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// Stream of writes.
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// During this time, the file may be moved e.g. by logRotate.
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for i := 0; i < 60; i++ {
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af.Write([]byte(Fmt("LOOP(%v)", i)))
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time.Sleep(time.Second)
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}
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// Close the AutoFile
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err = af.Close()
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if err != nil {
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panic(err)
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}
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*/
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const (
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autoFileClosePeriod = 1000 * time.Millisecond
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autoFilePerms = os.FileMode(0600)
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)
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// AutoFile automatically closes and re-opens file for writing. The file is
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// automatically setup to close itself every 1s and upon receiving SIGHUP.
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//
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// This is useful for using a log file with the logrotate tool.
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type AutoFile struct {
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ID string
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Path string
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closeTicker *time.Ticker
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closeTickerStopc chan struct{} // closed when closeTicker is stopped
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hupc chan os.Signal
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mtx sync.Mutex
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file *os.File
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}
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// OpenAutoFile creates an AutoFile in the path (with random ID). If there is
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// an error, it will be of type *PathError or *ErrPermissionsChanged (if file's
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// permissions got changed (should be 0600)).
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func OpenAutoFile(path string) (*AutoFile, error) {
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af := &AutoFile{
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ID: cmn.RandStr(12) + ":" + path,
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Path: path,
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closeTicker: time.NewTicker(autoFileClosePeriod),
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closeTickerStopc: make(chan struct{}),
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}
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if err := af.openFile(); err != nil {
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af.Close()
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return nil, err
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}
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// Close file on SIGHUP.
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af.hupc = make(chan os.Signal, 1)
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signal.Notify(af.hupc, syscall.SIGHUP)
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go func() {
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for range af.hupc {
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af.closeFile()
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}
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}()
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go af.closeFileRoutine()
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return af, nil
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}
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// Close shuts down the closing goroutine, SIGHUP handler and closes the
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// AutoFile.
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func (af *AutoFile) Close() error {
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af.closeTicker.Stop()
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close(af.closeTickerStopc)
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if af.hupc != nil {
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close(af.hupc)
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}
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return af.closeFile()
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}
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func (af *AutoFile) closeFileRoutine() {
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for {
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select {
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case <-af.closeTicker.C:
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af.closeFile()
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case <-af.closeTickerStopc:
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return
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}
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}
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}
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func (af *AutoFile) closeFile() (err error) {
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af.mtx.Lock()
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defer af.mtx.Unlock()
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file := af.file
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if file == nil {
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return nil
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}
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af.file = nil
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return file.Close()
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}
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// Write writes len(b) bytes to the AutoFile. It returns the number of bytes
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// written and an error, if any. Write returns a non-nil error when n !=
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// len(b).
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// Opens AutoFile if needed.
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func (af *AutoFile) Write(b []byte) (n int, err error) {
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af.mtx.Lock()
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defer af.mtx.Unlock()
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if af.file == nil {
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if err = af.openFile(); err != nil {
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return
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}
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}
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n, err = af.file.Write(b)
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return
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}
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// Sync commits the current contents of the file to stable storage. Typically,
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// this means flushing the file system's in-memory copy of recently written
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// data to disk.
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// Opens AutoFile if needed.
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func (af *AutoFile) Sync() error {
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af.mtx.Lock()
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defer af.mtx.Unlock()
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if af.file == nil {
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if err := af.openFile(); err != nil {
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return err
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}
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}
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return af.file.Sync()
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}
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func (af *AutoFile) openFile() error {
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file, err := os.OpenFile(af.Path, os.O_RDWR|os.O_CREATE|os.O_APPEND, autoFilePerms)
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if err != nil {
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return err
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}
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fileInfo, err := file.Stat()
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if err != nil {
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return err
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}
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if fileInfo.Mode() != autoFilePerms {
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return errors.NewErrPermissionsChanged(file.Name(), fileInfo.Mode(), autoFilePerms)
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}
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af.file = file
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return nil
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}
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// Size returns the size of the AutoFile. It returns -1 and an error if fails
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// get stats or open file.
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// Opens AutoFile if needed.
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func (af *AutoFile) Size() (int64, error) {
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af.mtx.Lock()
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defer af.mtx.Unlock()
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if af.file == nil {
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if err := af.openFile(); err != nil {
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return -1, err
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}
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}
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stat, err := af.file.Stat()
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if err != nil {
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return -1, err
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}
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return stat.Size(), nil
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}
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