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124 lines
3.2 KiB
124 lines
3.2 KiB
// Go support for leveled logs, analogous to https://code.google.com/p/google-glog/
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//
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// Copyright 2013 Google Inc. All Rights Reserved.
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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// File I/O for logs.
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package glog
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import (
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"errors"
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"flag"
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"fmt"
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"os"
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"os/user"
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"path/filepath"
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"strings"
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"sync"
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"time"
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)
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// MaxSize is the maximum size of a log file in bytes.
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var MaxSize uint64 = 1024 * 1024 * 1800
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// logDirs lists the candidate directories for new log files.
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var logDirs []string
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// If non-empty, overrides the choice of directory in which to write logs.
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// See createLogDirs for the full list of possible destinations.
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var logDir = flag.String("log_dir", "", "If non-empty, write log files in this directory")
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func createLogDirs() {
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if *logDir != "" {
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logDirs = append(logDirs, *logDir)
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}
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logDirs = append(logDirs, os.TempDir())
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}
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var (
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pid = os.Getpid()
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program = filepath.Base(os.Args[0])
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host = "unknownhost"
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userName = "unknownuser"
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)
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func init() {
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h, err := os.Hostname()
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if err == nil {
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host = shortHostname(h)
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}
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current, err := user.Current()
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if err == nil {
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userName = current.Username
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}
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// Sanitize userName since it may contain filepath separators on Windows.
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userName = strings.Replace(userName, `\`, "_", -1)
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}
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// shortHostname returns its argument, truncating at the first period.
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// For instance, given "www.google.com" it returns "www".
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func shortHostname(hostname string) string {
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if i := strings.Index(hostname, "."); i >= 0 {
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return hostname[:i]
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}
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return hostname
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}
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// logName returns a new log file name containing tag, with start time t, and
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// the name for the symlink for tag.
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func logName(tag string, t time.Time) (name, link string) {
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name = fmt.Sprintf("%s.%s.%s.log.%s.%04d%02d%02d-%02d%02d%02d.%d",
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program,
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host,
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userName,
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tag,
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t.Year(),
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t.Month(),
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t.Day(),
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t.Hour(),
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t.Minute(),
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t.Second(),
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pid)
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return name, program + "." + tag
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}
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var onceLogDirs sync.Once
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// create creates a new log file and returns the file and its filename, which
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// contains tag ("INFO", "FATAL", etc.) and t. If the file is created
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// successfully, create also attempts to update the symlink for that tag, ignoring
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// errors.
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func create(tag string, t time.Time) (f *os.File, filename string, err error) {
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onceLogDirs.Do(createLogDirs)
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if len(logDirs) == 0 {
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return nil, "", errors.New("log: no log dirs")
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}
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name, link := logName(tag, t)
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var lastErr error
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for _, dir := range logDirs {
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fname := filepath.Join(dir, name)
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f, err := os.Create(fname)
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if err == nil {
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symlink := filepath.Join(dir, link)
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os.Remove(symlink) // ignore err
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os.Symlink(name, symlink) // ignore err
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return f, fname, nil
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}
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lastErr = err
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}
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return nil, "", fmt.Errorf("log: cannot create log: %v", lastErr)
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}
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