blob: a70eb9f6b9319bc1a7a7a7d7a8ab1356d90bb478 [file] [log] [blame]
// Go support for leveled logs, analogous to https://code.google.com/p/google-glog/
//
// Copyright 2013 Google Inc. All Rights Reserved.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
// Package glog implements logging analogous to the Google-internal C++ INFO/ERROR/V setup.
// It provides functions Info, Warning, Error, Fatal, plus formatting variants such as
// Infof. It also provides V-style logging controlled by the -v and -vmodule=file=2 flags.
//
// Basic examples:
//
// glog.Info("Prepare to repel boarders")
//
// glog.Fatalf("Initialization failed: %s", err)
//
// See the documentation for the V function for an explanation of these examples:
//
// if glog.V(2) {
// glog.Info("Starting transaction...")
// }
//
// glog.V(2).Infoln("Processed", nItems, "elements")
//
// Log output is buffered and written periodically using Flush. Programs
// should call Flush before exiting to guarantee all log output is written.
//
// By default, all log statements write to files in a temporary directory.
// This package provides several flags that modify this behavior.
// As a result, flag.Parse must be called before any logging is done.
//
// -logtostderr=false
// Logs are written to standard error instead of to files.
// -alsologtostderr=false
// Logs are written to standard error as well as to files.
// -stderrthreshold=ERROR
// Log events at or above this severity are logged to standard
// error as well as to files.
// -log_dir=""
// Log files will be written to this directory instead of the
// default temporary directory.
//
// Other flags provide aids to debugging.
//
// -log_backtrace_at=""
// When set to a file and line number holding a logging statement,
// such as
// -log_backtrace_at=gopherflakes.go:234
// a stack trace will be written to the Info log whenever execution
// hits that statement. (Unlike with -vmodule, the ".go" must be
// present.)
// -v=0
// Enable V-leveled logging at the specified level.
// -vmodule=""
// The syntax of the argument is a comma-separated list of pattern=N,
// where pattern is a literal file name (minus the ".go" suffix) or
// "glob" pattern and N is a V level. For instance,
// -vmodule=gopher*=3
// sets the V level to 3 in all Go files whose names begin "gopher".
//
package glog
import (
"bufio"
"bytes"
"errors"
"flag"
"fmt"
"io"
stdLog "log"
"os"
"path/filepath"
"runtime"
"strconv"
"strings"
"sync"
"sync/atomic"
"time"
)
// severity identifies the sort of log: info, warning etc. It also implements
// the flag.Value interface. The -stderrthreshold flag is of type severity and
// should be modified only through the flag.Value interface. The values match
// the corresponding constants in C++.
type severity int32 // sync/atomic int32
// These constants identify the log levels in order of increasing severity.
// A message written to a high-severity log file is also written to each
// lower-severity log file.
const (
infoLog severity = iota
warningLog
errorLog
fatalLog
numSeverity = 4
)
const severityChar = "IWEF"
var severityName = []string{
infoLog: "INFO",
warningLog: "WARNING",
errorLog: "ERROR",
fatalLog: "FATAL",
}
// get returns the value of the severity.
func (s *severity) get() severity {
return severity(atomic.LoadInt32((*int32)(s)))
}
// set sets the value of the severity.
func (s *severity) set(val severity) {
atomic.StoreInt32((*int32)(s), int32(val))
}
// String is part of the flag.Value interface.
func (s *severity) String() string {
return strconv.FormatInt(int64(*s), 10)
}
// Get is part of the flag.Value interface.
func (s *severity) Get() interface{} {
return *s
}
// Set is part of the flag.Value interface.
func (s *severity) Set(value string) error {
var threshold severity
// Is it a known name?
if v, ok := severityByName(value); ok {
threshold = v
} else {
v, err := strconv.Atoi(value)
if err != nil {
return err
}
threshold = severity(v)
}
logging.stderrThreshold.set(threshold)
return nil
}
func severityByName(s string) (severity, bool) {
s = strings.ToUpper(s)
for i, name := range severityName {
if name == s {
return severity(i), true
}
}
return 0, false
}
// OutputStats tracks the number of output lines and bytes written.
type OutputStats struct {
lines int64
bytes int64
}
// Lines returns the number of lines written.
func (s *OutputStats) Lines() int64 {
return atomic.LoadInt64(&s.lines)
}
// Bytes returns the number of bytes written.
func (s *OutputStats) Bytes() int64 {
return atomic.LoadInt64(&s.bytes)
}
// Stats tracks the number of lines of output and number of bytes
// per severity level. Values must be read with atomic.LoadInt64.
var Stats struct {
Info, Warning, Error OutputStats
}
var severityStats = [numSeverity]*OutputStats{
infoLog: &Stats.Info,
warningLog: &Stats.Warning,
errorLog: &Stats.Error,
}
// Level is exported because it appears in the arguments to V and is
// the type of the v flag, which can be set programmatically.
// It's a distinct type because we want to discriminate it from logType.
// Variables of type level are only changed under logging.mu.
// The -v flag is read only with atomic ops, so the state of the logging
// module is consistent.
// Level is treated as a sync/atomic int32.
// Level specifies a level of verbosity for V logs. *Level implements
// flag.Value; the -v flag is of type Level and should be modified
// only through the flag.Value interface.
type Level int32
// get returns the value of the Level.
func (l *Level) get() Level {
return Level(atomic.LoadInt32((*int32)(l)))
}
// set sets the value of the Level.
func (l *Level) set(val Level) {
atomic.StoreInt32((*int32)(l), int32(val))
}
// String is part of the flag.Value interface.
func (l *Level) String() string {
return strconv.FormatInt(int64(*l), 10)
}
// Get is part of the flag.Value interface.
func (l *Level) Get() interface{} {
return *l
}
// Set is part of the flag.Value interface.
func (l *Level) Set(value string) error {
v, err := strconv.Atoi(value)
if err != nil {
return err
}
logging.mu.Lock()
defer logging.mu.Unlock()
logging.setVState(Level(v), logging.vmodule.filter, false)
return nil
}
// moduleSpec represents the setting of the -vmodule flag.
type moduleSpec struct {
filter []modulePat
}
// modulePat contains a filter for the -vmodule flag.
// It holds a verbosity level and a file pattern to match.
type modulePat struct {
pattern string
literal bool // The pattern is a literal string
level Level
}
// match reports whether the file matches the pattern. It uses a string
// comparison if the pattern contains no metacharacters.
func (m *modulePat) match(file string) bool {
if m.literal {
return file == m.pattern
}
match, _ := filepath.Match(m.pattern, file)
return match
}
func (m *moduleSpec) String() string {
// Lock because the type is not atomic. TODO: clean this up.
logging.mu.Lock()
defer logging.mu.Unlock()
var b bytes.Buffer
for i, f := range m.filter {
if i > 0 {
b.WriteRune(',')
}
fmt.Fprintf(&b, "%s=%d", f.pattern, f.level)
}
return b.String()
}
// Get is part of the (Go 1.2) flag.Getter interface. It always returns nil for this flag type since the
// struct is not exported.
func (m *moduleSpec) Get() interface{} {
return nil
}
var errVmoduleSyntax = errors.New("syntax error: expect comma-separated list of filename=N")
// Syntax: -vmodule=recordio=2,file=1,gfs*=3
func (m *moduleSpec) Set(value string) error {
var filter []modulePat
for _, pat := range strings.Split(value, ",") {
if len(pat) == 0 {
// Empty strings such as from a trailing comma can be ignored.
continue
}
patLev := strings.Split(pat, "=")
if len(patLev) != 2 || len(patLev[0]) == 0 || len(patLev[1]) == 0 {
return errVmoduleSyntax
}
pattern := patLev[0]
v, err := strconv.Atoi(patLev[1])
if err != nil {
return errors.New("syntax error: expect comma-separated list of filename=N")
}
if v < 0 {
return errors.New("negative value for vmodule level")
}
if v == 0 {
continue // Ignore. It's harmless but no point in paying the overhead.
}
// TODO: check syntax of filter?
filter = append(filter, modulePat{pattern, isLiteral(pattern), Level(v)})
}
logging.mu.Lock()
defer logging.mu.Unlock()
logging.setVState(logging.verbosity, filter, true)
return nil
}
// isLiteral reports whether the pattern is a literal string, that is, has no metacharacters
// that require filepath.Match to be called to match the pattern.
func isLiteral(pattern string) bool {
return !strings.ContainsAny(pattern, `\*?[]`)
}
// traceLocation represents the setting of the -log_backtrace_at flag.
type traceLocation struct {
file string
line int
}
// isSet reports whether the trace location has been specified.
// logging.mu is held.
func (t *traceLocation) isSet() bool {
return t.line > 0
}
// match reports whether the specified file and line matches the trace location.
// The argument file name is the full path, not the basename specified in the flag.
// logging.mu is held.
func (t *traceLocation) match(file string, line int) bool {
if t.line != line {
return false
}
if i := strings.LastIndex(file, "/"); i >= 0 {
file = file[i+1:]
}
return t.file == file
}
func (t *traceLocation) String() string {
// Lock because the type is not atomic. TODO: clean this up.
logging.mu.Lock()
defer logging.mu.Unlock()
return fmt.Sprintf("%s:%d", t.file, t.line)
}
// Get is part of the (Go 1.2) flag.Getter interface. It always returns nil for this flag type since the
// struct is not exported
func (t *traceLocation) Get() interface{} {
return nil
}
var errTraceSyntax = errors.New("syntax error: expect file.go:234")
// Syntax: -log_backtrace_at=gopherflakes.go:234
// Note that unlike vmodule the file extension is included here.
func (t *traceLocation) Set(value string) error {
if value == "" {
// Unset.
t.line = 0
t.file = ""
}
fields := strings.Split(value, ":")
if len(fields) != 2 {
return errTraceSyntax
}
file, line := fields[0], fields[1]
if !strings.Contains(file, ".") {
return errTraceSyntax
}
v, err := strconv.Atoi(line)
if err != nil {
return errTraceSyntax
}
if v <= 0 {
return errors.New("negative or zero value for level")
}
logging.mu.Lock()
defer logging.mu.Unlock()
t.line = v
t.file = file
return nil
}
// flushSyncWriter is the interface satisfied by logging destinations.
type flushSyncWriter interface {
Flush() error
Sync() error
io.Writer
}
func init() {
flag.BoolVar(&logging.toStderr, "logtostderr", false, "log to standard error instead of files")
flag.BoolVar(&logging.alsoToStderr, "alsologtostderr", false, "log to standard error as well as files")
flag.Var(&logging.verbosity, "v", "log level for V logs")
flag.Var(&logging.stderrThreshold, "stderrthreshold", "logs at or above this threshold go to stderr")
flag.Var(&logging.vmodule, "vmodule", "comma-separated list of pattern=N settings for file-filtered logging")
flag.Var(&logging.traceLocation, "log_backtrace_at", "when logging hits line file:N, emit a stack trace")
// Default stderrThreshold is ERROR.
logging.stderrThreshold = errorLog
logging.setVState(0, nil, false)
go logging.flushDaemon()
}
// Flush flushes all pending log I/O.
func Flush() {
logging.lockAndFlushAll()
}
// loggingT collects all the global state of the logging setup.
type loggingT struct {
// Boolean flags. Not handled atomically because the flag.Value interface
// does not let us avoid the =true, and that shorthand is necessary for
// compatibility. TODO: does this matter enough to fix? Seems unlikely.
toStderr bool // The -logtostderr flag.
alsoToStderr bool // The -alsologtostderr flag.
// Level flag. Handled atomically.
stderrThreshold severity // The -stderrthreshold flag.
// freeList is a list of byte buffers, maintained under freeListMu.
freeList *buffer
// freeListMu maintains the free list. It is separate from the main mutex
// so buffers can be grabbed and printed to without holding the main lock,
// for better parallelization.
freeListMu sync.Mutex
// mu protects the remaining elements of this structure and is
// used to synchronize logging.
mu sync.Mutex
// file holds writer for each of the log types.
file [numSeverity]flushSyncWriter
// pcs is used in V to avoid an allocation when computing the caller's PC.
pcs [1]uintptr
// vmap is a cache of the V Level for each V() call site, identified by PC.
// It is wiped whenever the vmodule flag changes state.
vmap map[uintptr]Level
// filterLength stores the length of the vmodule filter chain. If greater
// than zero, it means vmodule is enabled. It may be read safely
// using sync.LoadInt32, but is only modified under mu.
filterLength int32
// traceLocation is the state of the -log_backtrace_at flag.
traceLocation traceLocation
// These flags are modified only under lock, although verbosity may be fetched
// safely using atomic.LoadInt32.
vmodule moduleSpec // The state of the -vmodule flag.
verbosity Level // V logging level, the value of the -v flag/
}
// buffer holds a byte Buffer for reuse. The zero value is ready for use.
type buffer struct {
bytes.Buffer
tmp [64]byte // temporary byte array for creating headers.
next *buffer
}
var logging loggingT
// setVState sets a consistent state for V logging.
// l.mu is held.
func (l *loggingT) setVState(verbosity Level, filter []modulePat, setFilter bool) {
// Turn verbosity off so V will not fire while we are in transition.
logging.verbosity.set(0)
// Ditto for filter length.
atomic.StoreInt32(&logging.filterLength, 0)
// Set the new filters and wipe the pc->Level map if the filter has changed.
if setFilter {
logging.vmodule.filter = filter
logging.vmap = make(map[uintptr]Level)
}
// Things are consistent now, so enable filtering and verbosity.
// They are enabled in order opposite to that in V.
atomic.StoreInt32(&logging.filterLength, int32(len(filter)))
logging.verbosity.set(verbosity)
}
// getBuffer returns a new, ready-to-use buffer.
func (l *loggingT) getBuffer() *buffer {
l.freeListMu.Lock()
b := l.freeList
if b != nil {
l.freeList = b.next
}
l.freeListMu.Unlock()
if b == nil {
b = new(buffer)
} else {
b.next = nil
b.Reset()
}
return b
}
// putBuffer returns a buffer to the free list.
func (l *loggingT) putBuffer(b *buffer) {
if b.Len() >= 256 {
// Let big buffers die a natural death.
return
}
l.freeListMu.Lock()
b.next = l.freeList
l.freeList = b
l.freeListMu.Unlock()
}
var timeNow = time.Now // Stubbed out for testing.
/*
header formats a log header as defined by the C++ implementation.
It returns a buffer containing the formatted header and the user's file and line number.
Log lines have this form:
Lmmdd hh:mm:ss.uuuuuu threadid file:line] msg...
where the fields are defined as follows:
L A single character, representing the log level (eg 'I' for INFO)
mm The month (zero padded; ie May is '05')
dd The day (zero padded)
hh:mm:ss.uuuuuu Time in hours, minutes and fractional seconds
threadid The space-padded thread ID as returned by GetTID()
file The file name
line The line number
msg The user-supplied message
*/
func (l *loggingT) header(s severity) (*buffer, string, int) {
_, file, line, ok := runtime.Caller(3) // It's always the same number of frames to the user's call.
if !ok {
file = "???"
line = 1
} else {
slash := strings.LastIndex(file, "/")
if slash >= 0 {
file = file[slash+1:]
}
}
return l.formatHeader(s, file, line), file, line
}
// formatHeader formats a log header using the provided file name and line number.
func (l *loggingT) formatHeader(s severity, file string, line int) *buffer {
now := timeNow()
if line < 0 {
line = 0 // not a real line number, but acceptable to someDigits
}
if s > fatalLog {
s = infoLog // for safety.
}
buf := l.getBuffer()
// Avoid Fprintf, for speed. The format is so simple that we can do it quickly by hand.
// It's worth about 3X. Fprintf is hard.
_, month, day := now.Date()
hour, minute, second := now.Clock()
// Lmmdd hh:mm:ss.uuuuuu threadid file:line]
buf.tmp[0] = severityChar[s]
buf.twoDigits(1, int(month))
buf.twoDigits(3, day)
buf.tmp[5] = ' '
buf.twoDigits(6, hour)
buf.tmp[8] = ':'
buf.twoDigits(9, minute)
buf.tmp[11] = ':'
buf.twoDigits(12, second)
buf.tmp[14] = '.'
buf.nDigits(6, 15, now.Nanosecond()/1000, '0')
buf.tmp[21] = ' '
buf.nDigits(5, 22, pid, ' ') // TODO: should be TID
buf.tmp[27] = ' '
buf.Write(buf.tmp[:28])
buf.WriteString(file)
buf.tmp[0] = ':'
n := buf.someDigits(1, line)
buf.tmp[n+1] = ']'
buf.tmp[n+2] = ' '
buf.Write(buf.tmp[:n+3])
return buf
}
// Some custom tiny helper functions to print the log header efficiently.
const digits = "0123456789"
// twoDigits formats a zero-prefixed two-digit integer at buf.tmp[i].
func (buf *buffer) twoDigits(i, d int) {
buf.tmp[i+1] = digits[d%10]
d /= 10
buf.tmp[i] = digits[d%10]
}
// nDigits formats an n-digit integer at buf.tmp[i],
// padding with pad on the left.
// It assumes d >= 0.
func (buf *buffer) nDigits(n, i, d int, pad byte) {
j := n - 1
for ; j >= 0 && d > 0; j-- {
buf.tmp[i+j] = digits[d%10]
d /= 10
}
for ; j >= 0; j-- {
buf.tmp[i+j] = pad
}
}
// someDigits formats a zero-prefixed variable-width integer at buf.tmp[i].
func (buf *buffer) someDigits(i, d int) int {
// Print into the top, then copy down. We know there's space for at least
// a 10-digit number.
j := len(buf.tmp)
for {
j--
buf.tmp[j] = digits[d%10]
d /= 10
if d == 0 {
break
}
}
return copy(buf.tmp[i:], buf.tmp[j:])
}
func (l *loggingT) println(s severity, args ...interface{}) {
buf, file, line := l.header(s)
fmt.Fprintln(buf, args...)
l.output(s, buf, file, line, false)
}
func (l *loggingT) print(s severity, args ...interface{}) {
buf, file, line := l.header(s)
fmt.Fprint(buf, args...)
if buf.Bytes()[buf.Len()-1] != '\n' {
buf.WriteByte('\n')
}
l.output(s, buf, file, line, false)
}
func (l *loggingT) printf(s severity, format string, args ...interface{}) {
buf, file, line := l.header(s)
fmt.Fprintf(buf, format, args...)
if buf.Bytes()[buf.Len()-1] != '\n' {
buf.WriteByte('\n')
}
l.output(s, buf, file, line, false)
}
// printWithFileLine behaves like print but uses the provided file and line number. If
// alsoLogToStderr is true, the log message always appears on standard error; it
// will also appear in the log file unless --logtostderr is set.
func (l *loggingT) printWithFileLine(s severity, file string, line int, alsoToStderr bool, args ...interface{}) {
buf := l.formatHeader(s, file, line)
fmt.Fprint(buf, args...)
if buf.Bytes()[buf.Len()-1] != '\n' {
buf.WriteByte('\n')
}
l.output(s, buf, file, line, alsoToStderr)
}
// output writes the data to the log files and releases the buffer.
func (l *loggingT) output(s severity, buf *buffer, file string, line int, alsoToStderr bool) {
l.mu.Lock()
if l.traceLocation.isSet() {
if l.traceLocation.match(file, line) {
buf.Write(stacks(false))
}
}
data := buf.Bytes()
if l.toStderr {
os.Stderr.Write(data)
} else {
if alsoToStderr || l.alsoToStderr || s >= l.stderrThreshold.get() {
os.Stderr.Write(data)
}
if l.file[s] == nil {
if err := l.createFiles(s); err != nil {
os.Stderr.Write(data) // Make sure the message appears somewhere.
l.exit(err)
}
}
switch s {
case fatalLog:
l.file[fatalLog].Write(data)
fallthrough
case errorLog:
l.file[errorLog].Write(data)
fallthrough
case warningLog:
l.file[warningLog].Write(data)
fallthrough
case infoLog:
l.file[infoLog].Write(data)
}
}
if s == fatalLog {
// Make sure we see the trace for the current goroutine on standard error.
if !l.toStderr {
os.Stderr.Write(stacks(false))
}
// Write the stack trace for all goroutines to the files.
trace := stacks(true)
logExitFunc = func(error) {} // If we get a write error, we'll still exit below.
for log := fatalLog; log >= infoLog; log-- {
if f := l.file[log]; f != nil { // Can be nil if -logtostderr is set.
f.Write(trace)
}
}
l.mu.Unlock()
timeoutFlush(10 * time.Second)
os.Exit(255) // C++ uses -1, which is silly because it's anded with 255 anyway.
}
l.putBuffer(buf)
l.mu.Unlock()
if stats := severityStats[s]; stats != nil {
atomic.AddInt64(&stats.lines, 1)
atomic.AddInt64(&stats.bytes, int64(len(data)))
}
}
// timeoutFlush calls Flush and returns when it completes or after timeout
// elapses, whichever happens first. This is needed because the hooks invoked
// by Flush may deadlock when glog.Fatal is called from a hook that holds
// a lock.
func timeoutFlush(timeout time.Duration) {
done := make(chan bool, 1)
go func() {
Flush() // calls logging.lockAndFlushAll()
done <- true
}()
select {
case <-done:
case <-time.After(timeout):
fmt.Fprintln(os.Stderr, "glog: Flush took longer than", timeout)
}
}
// stacks is a wrapper for runtime.Stack that attempts to recover the data for all goroutines.
func stacks(all bool) []byte {
// We don't know how big the traces are, so grow a few times if they don't fit. Start large, though.
n := 10000
if all {
n = 100000
}
var trace []byte
for i := 0; i < 5; i++ {
trace = make([]byte, n)
nbytes := runtime.Stack(trace, all)
if nbytes < len(trace) {
return trace[:nbytes]
}
n *= 2
}
return trace
}
// logExitFunc provides a simple mechanism to override the default behavior
// of exiting on error. Used in testing and to guarantee we reach a required exit
// for fatal logs. Instead, exit could be a function rather than a method but that
// would make its use clumsier.
var logExitFunc func(error)
// exit is called if there is trouble creating or writing log files.
// It flushes the logs and exits the program; there's no point in hanging around.
// l.mu is held.
func (l *loggingT) exit(err error) {
fmt.Fprintf(os.Stderr, "log: exiting because of error: %s\n", err)
// If logExitFunc is set, we do that instead of exiting.
if logExitFunc != nil {
logExitFunc(err)
return
}
l.flushAll()
os.Exit(2)
}
// syncBuffer joins a bufio.Writer to its underlying file, providing access to the
// file's Sync method and providing a wrapper for the Write method that provides log
// file rotation. There are conflicting methods, so the file cannot be embedded.
// l.mu is held for all its methods.
type syncBuffer struct {
logger *loggingT
*bufio.Writer
file *os.File
sev severity
nbytes uint64 // The number of bytes written to this file
}
func (sb *syncBuffer) Sync() error {
return sb.file.Sync()
}
func (sb *syncBuffer) Write(p []byte) (n int, err error) {
if sb.nbytes+uint64(len(p)) >= MaxSize {
if err := sb.rotateFile(time.Now()); err != nil {
sb.logger.exit(err)
}
}
n, err = sb.Writer.Write(p)
sb.nbytes += uint64(n)
if err != nil {
sb.logger.exit(err)
}
return
}
// rotateFile closes the syncBuffer's file and starts a new one.
func (sb *syncBuffer) rotateFile(now time.Time) error {
if sb.file != nil {
sb.Flush()
sb.file.Close()
}
var err error
sb.file, _, err = create(severityName[sb.sev], now)
sb.nbytes = 0
if err != nil {
return err
}
sb.Writer = bufio.NewWriterSize(sb.file, bufferSize)
// Write header.
var buf bytes.Buffer
fmt.Fprintf(&buf, "Log file created at: %s\n", now.Format("2006/01/02 15:04:05"))
fmt.Fprintf(&buf, "Running on machine: %s\n", host)
fmt.Fprintf(&buf, "Binary: Built with %s %s for %s/%s\n", runtime.Compiler, runtime.Version(), runtime.GOOS, runtime.GOARCH)
fmt.Fprintf(&buf, "Log line format: [IWEF]mmdd hh:mm:ss.uuuuuu threadid file:line] msg\n")
n, err := sb.file.Write(buf.Bytes())
sb.nbytes += uint64(n)
return err
}
// bufferSize sizes the buffer associated with each log file. It's large
// so that log records can accumulate without the logging thread blocking
// on disk I/O. The flushDaemon will block instead.
const bufferSize = 256 * 1024
// createFiles creates all the log files for severity from sev down to infoLog.
// l.mu is held.
func (l *loggingT) createFiles(sev severity) error {
now := time.Now()
// Files are created in decreasing severity order, so as soon as we find one
// has already been created, we can stop.
for s := sev; s >= infoLog && l.file[s] == nil; s-- {
sb := &syncBuffer{
logger: l,
sev: s,
}
if err := sb.rotateFile(now); err != nil {
return err
}
l.file[s] = sb
}
return nil
}
const flushInterval = 30 * time.Second
// flushDaemon periodically flushes the log file buffers.
func (l *loggingT) flushDaemon() {
for _ = range time.NewTicker(flushInterval).C {
l.lockAndFlushAll()
}
}
// lockAndFlushAll is like flushAll but locks l.mu first.
func (l *loggingT) lockAndFlushAll() {
l.mu.Lock()
l.flushAll()
l.mu.Unlock()
}
// flushAll flushes all the logs and attempts to "sync" their data to disk.
// l.mu is held.
func (l *loggingT) flushAll() {
// Flush from fatal down, in case there's trouble flushing.
for s := fatalLog; s >= infoLog; s-- {
file := l.file[s]
if file != nil {
file.Flush() // ignore error
file.Sync() // ignore error
}
}
}
// CopyStandardLogTo arranges for messages written to the Go "log" package's
// default logs to also appear in the Google logs for the named and lower
// severities. Subsequent changes to the standard log's default output location
// or format may break this behavior.
//
// Valid names are "INFO", "WARNING", "ERROR", and "FATAL". If the name is not
// recognized, CopyStandardLogTo panics.
func CopyStandardLogTo(name string) {
sev, ok := severityByName(name)
if !ok {
panic(fmt.Sprintf("log.CopyStandardLogTo(%q): unrecognized severity name", name))
}
// Set a log format that captures the user's file and line:
// d.go:23: message
stdLog.SetFlags(stdLog.Lshortfile)
stdLog.SetOutput(logBridge(sev))
}
// logBridge provides the Write method that enables CopyStandardLogTo to connect
// Go's standard logs to the logs provided by this package.
type logBridge severity
// Write parses the standard logging line and passes its components to the
// logger for severity(lb).
func (lb logBridge) Write(b []byte) (n int, err error) {
var (
file = "???"
line = 1
text string
)
// Split "d.go:23: message" into "d.go", "23", and "message".
if parts := bytes.SplitN(b, []byte{':'}, 3); len(parts) != 3 || len(parts[0]) < 1 || len(parts[2]) < 1 {
text = fmt.Sprintf("bad log format: %s", b)
} else {
file = string(parts[0])
text = string(parts[2][1:]) // skip leading space
line, err = strconv.Atoi(string(parts[1]))
if err != nil {
text = fmt.Sprintf("bad line number: %s", b)
line = 1
}
}
// printWithFileLine with alsoToStderr=true, so standard log messages
// always appear on standard error.
logging.printWithFileLine(severity(lb), file, line, true, text)
return len(b), nil
}
// setV computes and remembers the V level for a given PC
// when vmodule is enabled.
// File pattern matching takes the basename of the file, stripped
// of its .go suffix, and uses filepath.Match, which is a little more
// general than the *? matching used in C++.
// l.mu is held.
func (l *loggingT) setV(pc uintptr) Level {
fn := runtime.FuncForPC(pc)
file, _ := fn.FileLine(pc)
// The file is something like /a/b/c/d.go. We want just the d.
if strings.HasSuffix(file, ".go") {
file = file[:len(file)-3]
}
if slash := strings.LastIndex(file, "/"); slash >= 0 {
file = file[slash+1:]
}
for _, filter := range l.vmodule.filter {
if filter.match(file) {
l.vmap[pc] = filter.level
return filter.level
}
}
l.vmap[pc] = 0
return 0
}
// Verbose is a boolean type that implements Infof (like Printf) etc.
// See the documentation of V for more information.
type Verbose bool
// V reports whether verbosity at the call site is at least the requested level.
// The returned value is a boolean of type Verbose, which implements Info, Infoln
// and Infof. These methods will write to the Info log if called.
// Thus, one may write either
// if glog.V(2) { glog.Info("log this") }
// or
// glog.V(2).Info("log this")
// The second form is shorter but the first is cheaper if logging is off because it does
// not evaluate its arguments.
//
// Whether an individual call to V generates a log record depends on the setting of
// the -v and --vmodule flags; both are off by default. If the level in the call to
// V is at least the value of -v, or of -vmodule for the source file containing the
// call, the V call will log.
func V(level Level) Verbose {
// This function tries hard to be cheap unless there's work to do.
// The fast path is two atomic loads and compares.
// Here is a cheap but safe test to see if V logging is enabled globally.
if logging.verbosity.get() >= level {
return Verbose(true)
}
// It's off globally but it vmodule may still be set.
// Here is another cheap but safe test to see if vmodule is enabled.
if atomic.LoadInt32(&logging.filterLength) > 0 {
// Now we need a proper lock to use the logging structure. The pcs field
// is shared so we must lock before accessing it. This is fairly expensive,
// but if V logging is enabled we're slow anyway.
logging.mu.Lock()
defer logging.mu.Unlock()
if runtime.Callers(2, logging.pcs[:]) == 0 {
return Verbose(false)
}
v, ok := logging.vmap[logging.pcs[0]]
if !ok {
v = logging.setV(logging.pcs[0])
}
return Verbose(v >= level)
}
return Verbose(false)
}
// Info is equivalent to the global Info function, guarded by the value of v.
// See the documentation of V for usage.
func (v Verbose) Info(args ...interface{}) {
if v {
logging.print(infoLog, args...)
}
}
// Infoln is equivalent to the global Infoln function, guarded by the value of v.
// See the documentation of V for usage.
func (v Verbose) Infoln(args ...interface{}) {
if v {
logging.println(infoLog, args...)
}
}
// Infof is equivalent to the global Infof function, guarded by the value of v.
// See the documentation of V for usage.
func (v Verbose) Infof(format string, args ...interface{}) {
if v {
logging.printf(infoLog, format, args...)
}
}
// Info logs to the INFO log.
// Arguments are handled in the manner of fmt.Print; a newline is appended if missing.
func Info(args ...interface{}) {
logging.print(infoLog, args...)
}
// Infoln logs to the INFO log.
// Arguments are handled in the manner of fmt.Println; a newline is appended if missing.
func Infoln(args ...interface{}) {
logging.println(infoLog, args...)
}
// Infof logs to the INFO log.
// Arguments are handled in the manner of fmt.Printf; a newline is appended if missing.
func Infof(format string, args ...interface{}) {
logging.printf(infoLog, format, args...)
}
// Warning logs to the WARNING and INFO logs.
// Arguments are handled in the manner of fmt.Print; a newline is appended if missing.
func Warning(args ...interface{}) {
logging.print(warningLog, args...)
}
// Warningln logs to the WARNING and INFO logs.
// Arguments are handled in the manner of fmt.Println; a newline is appended if missing.
func Warningln(args ...interface{}) {
logging.println(warningLog, args...)
}
// Warningf logs to the WARNING and INFO logs.
// Arguments are handled in the manner of fmt.Printf; a newline is appended if missing.
func Warningf(format string, args ...interface{}) {
logging.printf(warningLog, format, args...)
}
// Error logs to the ERROR, WARNING, and INFO logs.
// Arguments are handled in the manner of fmt.Print; a newline is appended if missing.
func Error(args ...interface{}) {
logging.print(errorLog, args...)
}
// Errorln logs to the ERROR, WARNING, and INFO logs.
// Arguments are handled in the manner of fmt.Println; a newline is appended if missing.
func Errorln(args ...interface{}) {
logging.println(errorLog, args...)
}
// Errorf logs to the ERROR, WARNING, and INFO logs.
// Arguments are handled in the manner of fmt.Printf; a newline is appended if missing.
func Errorf(format string, args ...interface{}) {
logging.printf(errorLog, format, args...)
}
// Fatal logs to the FATAL, ERROR, WARNING, and INFO logs,
// including a stack trace of all running goroutines, then calls os.Exit(255).
// Arguments are handled in the manner of fmt.Print; a newline is appended if missing.
func Fatal(args ...interface{}) {
logging.print(fatalLog, args...)
}
// Fatalln logs to the FATAL, ERROR, WARNING, and INFO logs,
// including a stack trace of all running goroutines, then calls os.Exit(255).
// Arguments are handled in the manner of fmt.Println; a newline is appended if missing.
func Fatalln(args ...interface{}) {
logging.println(fatalLog, args...)
}
// Fatalf logs to the FATAL, ERROR, WARNING, and INFO logs,
// including a stack trace of all running goroutines, then calls os.Exit(255).
// Arguments are handled in the manner of fmt.Printf; a newline is appended if missing.
func Fatalf(format string, args ...interface{}) {
logging.printf(fatalLog, format, args...)
}