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appender.go
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appender.go
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package logo
import (
"bufio"
"bytes"
"fmt"
"io"
"os"
"path/filepath"
"strings"
"sync"
"time"
)
var defaultFormat = "%date %severity (%file:%line) - %message%newline"
// Appender is the interface describing a logger appender.
// Each logger may have one or more appenders and will call Append
// passing in a LogMessage. Append will format the message using
// the native format for the logger (normally defaultformat), or a
// custom format specified with SetFormat. Custom format strings comprise
// one or more percent tags. For example, %severity will include the
// log message severity. Many tags have shorthand too, e.g. %s has the
// same effect as %severity.
// SetFilters adds another level of granularity, restricting logging to
// messages which have a severity in the accepted list. For example, to
// restrict an appender to log only debug and warning messages:
// appender.SetFilters("debug", "warn")
// Close is called when the log manager is closed; Appender implementations
// must use this to flush and close any open files, connections, etc.
type Appender interface {
Append(m *LogMessage)
SetFormat(format string) error
Close()
SetFilters(f ...string)
}
// EmptyAppender is used for testing.
// All methods succeed, but perform no action.
var EmptyAppender = &emptyAppender{}
type emptyAppender struct{}
func (a *emptyAppender) Append(m *LogMessage) {}
func (a *emptyAppender) Close() {}
func (a *emptyAppender) SetFormat(format string) error { return nil }
func (a *emptyAppender) SetFilters(f ...string) {}
// ConsoleAppender writes formatted log messages to StdErr using the default format.
var ConsoleAppender = newConsoleAppender()
func newConsoleAppender() *consoleAppender {
a := consoleAppender{
out: os.Stderr,
}
a.SetFormat(defaultFormat)
a.SetFilters(severityName...)
return &a
}
type consoleAppender struct {
mu sync.Mutex
out io.Writer
formatters []Formatter
filters map[severity]bool
}
func (a *consoleAppender) SetFormat(format string) error {
f, err := extract(format)
if err != nil {
return err
}
a.formatters = f
return nil
}
func (a *consoleAppender) Append(m *LogMessage) {
m.Reset()
if !a.filters[m.severity] {
return
}
for _, f := range a.formatters {
f.Format(m)
}
a.Write(m.Bytes())
}
func (a *consoleAppender) Write(p []byte) (n int, err error) {
a.mu.Lock()
defer a.mu.Unlock()
return a.out.Write(p)
}
func (a *consoleAppender) SetFilters(f ...string) {
a.filters = make(map[severity]bool)
for _, n := range f {
s := severityFromName(n)
a.filters[s] = true
}
}
func (a *consoleAppender) Close() {
// to satisfy interface
}
// RollingFileConfig holds key parameters for configuring a RollingFileAppender.
// Filename must include the full path and logfile name. If only the file name
// is supplied, logging will be to the current directory.
// MaxFileSize is the maximum size in MB for an individual log file, before the
// appender rolls to a new file. New files can be created before an existing
// reaches its maximum size because of the way RollingFileAppender always
// creates new files at application start.
// New files are created with a date-time.PID suffix. For example, if the
// filename is "my.log", then log files will be named something like:
//
// my.log.20160726-091757.3160
//
// In certain environments, it is necessary to retain the original file
// extension. This can be achieved by setting the PreserveExtension property
// which would produce:
//
// my.20160726-091757.3160.log
type RollingFileConfig struct {
Filename string
MaxFileSize int
PreserveExtension bool
}
type rollingFileAppender struct {
*bufio.Writer
mu sync.Mutex
filename string
ext string
file *os.File
// TODO: split filename into dir & file parts
//directory *string
bytes uint64
max uint64
formatters []Formatter
filters map[severity]bool
}
// RollingFileAppender returns a new rollingfile appender instance.
// RollingFileAppender writes formatted log messages to the file specified in
// config. RollingFileAppender will create a new file each time the maximum
// filesize limit has been reached. New files are created with a date-time (and
// PID) based suffix, but the original filename extension can be preserved if
// required by setting the PreserveExtension config property.
//
// Old files are not deleted by this appender; it is up to the consumer to handle
// any purging.
//
// Note that RollingFileAppender will always create a new file at application
// start, and never opens an existing file to append to it. If an application is
// started and stopped quickly several times, then this will result in the
// creation of the same number of log files; even though max bytes may not have
// been written to any of them.
// RollingFileAppender buffers messages to improve performance and reduce
// blocking. Buffered data is written to disk every 30 seconds and when Close
// is called.
//
// RollingFileAppender uses the default format.
func RollingFileAppender(config RollingFileConfig) (Appender, error) {
m := uint64(config.MaxFileSize) * 1024 * 1024 // megabytes
a := rollingFileAppender{
filename: config.Filename,
max: m,
}
if config.PreserveExtension {
a.ext = filepath.Ext(a.filename)
a.filename = strings.TrimSuffix(a.filename, a.ext)
}
a.SetFormat(defaultFormat)
a.SetFilters(severityName...)
// if a.directory == nil {
// dir := filepath.Join(os.TempDir(), filepath.Base(os.Args[0]))
// a.directory = &dir
// }
err := a.rotate()
if err != nil {
return nil, err
}
go a.flusher()
return &a, nil
}
func (a *rollingFileAppender) SetFormat(format string) error {
f, err := extract(format)
if err != nil {
return err
}
a.formatters = f
return nil
}
func (a *rollingFileAppender) SetFilters(f ...string) {
a.filters = make(map[severity]bool)
for _, n := range f {
s := severityFromName(n)
a.filters[s] = true
}
}
func (a *rollingFileAppender) Append(m *LogMessage) {
m.Reset()
if !a.filters[m.severity] {
return
}
for _, f := range a.formatters {
f.Format(m)
}
a.Write(m.Bytes())
}
func (a *rollingFileAppender) Write(p []byte) (n int, err error) {
a.mu.Lock()
defer a.mu.Unlock()
if a.bytes+uint64(len(p)) >= a.max {
// TODO: consider what to do with any error from rotate().
// Just ignore and continue or exit the program?
// TODO: Call a LogRotateError() stub
a.rotate()
}
n, err = a.Writer.Write(p)
// TODO: Keep track of number of bytes written since last flush
// and force if 95% of max?
a.bytes += uint64(n)
return
}
const flushInterval = 30 * time.Second
func (a *rollingFileAppender) flusher() {
for _ = range time.NewTicker(flushInterval).C {
a.mu.Lock()
if a.Writer != nil {
a.Flush()
a.file.Sync()
}
a.mu.Unlock()
}
}
const bufferSize = 256 * 1024
func (a *rollingFileAppender) rotate() error {
if a.file != nil {
a.Close()
}
a.bytes = 0
name := logname(a.filename, a.ext)
var err error
a.file, err = os.Create(name)
if err != nil {
return err
}
//a.Writer = bufio.NewWriter(a.file) // default size is 4096
a.Writer = bufio.NewWriterSize(a.file, bufferSize)
//n, err := a.file.WriteString("New log created!\n")
//a.bytes = uint64(n)
return nil
}
var pid = os.Getpid()
func logname(fname string, ext string) string {
t := timenow().UTC()
return fmt.Sprintf("%s.%04d%02d%02d-%02d%02d%02d.%d%s",
fname,
t.Year(),
t.Month(),
t.Day(),
t.Hour(),
t.Minute(),
t.Second(),
pid,
ext)
}
func (a *rollingFileAppender) Close() {
if a.Writer != nil {
a.Flush()
a.file.Close()
a.Writer = nil
a.file = nil
}
}
// TestAppender is used for testing.
// Applications can specify this appender and verify logger calls
// by examining the properties: Messages, Format and Closed.
var TestAppender = newTestAppender()
func newTestAppender() *testAppender {
b := new(bytes.Buffer)
a := testAppender{
buf: b,
consoleAppender: &consoleAppender{out: b},
}
a.SetFormat(defaultFormat)
a.SetFilters(severityName...)
return &a
}
type testAppender struct {
*consoleAppender
logMessages []*LogMessage
Closed bool
Format string
Messages []string
buf *bytes.Buffer
}
func (a *testAppender) Append(m *LogMessage) {
n := &LogMessage{
format: m.format,
severity: m.severity,
name: m.name,
file: m.file,
line: m.line,
ctx: m.ctx,
timestamp: m.timestamp,
properties: make(map[string]interface{}, len(m.properties)),
}
for _, a := range m.args {
n.args = append(n.args, a)
}
for k, v := range m.properties {
n.properties[k] = v
}
a.logMessages = append(a.logMessages, n)
a.buf.Reset()
a.consoleAppender.Append(m)
s := string(a.buf.Bytes())
a.Messages = append(a.Messages, s)
}
func (a *testAppender) Close() {
a.consoleAppender.Close()
a.Closed = true
}
func (a *testAppender) SetFormat(format string) error {
a.Format = format
return a.consoleAppender.SetFormat(format)
}
func (a *testAppender) SetFilters(f ...string) {
a.consoleAppender.SetFilters(f...)
}
func (a *testAppender) Reset() {
a.logMessages = []*LogMessage{}
a.Messages = []string{}
a.Closed = false
a.buf.Reset()
a.SetFormat(defaultFormat)
}