micropelago/pmux
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Refactor logging to expose the default PmuxLogger

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This commit is contained in:
Brian Picciano 2024-10-29 12:03:52 +01:00
parent 65a9123af2
commit 5660a9a623
4 changed files with 103 additions and 84 deletions
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3
main.go
View File

@ -3,7 +3,6 @@ package main
import (
"flag"
"fmt"
"io/ioutil"
"os"
"os/signal"
"syscall"
@ -18,7 +17,7 @@ func main() {
cfgPath := flag.String("c", "./pmux.yml", "Path to config yaml file")
flag.Parse()
cfgB, err := ioutil.ReadFile(*cfgPath)
cfgB, err := os.ReadFile(*cfgPath)
if err != nil {
panic(fmt.Sprintf("couldn't read cfg file at %q: %v", *cfgPath, err))
}

92
pmuxlib/logger.go
View File

@ -4,7 +4,6 @@ import (
"bufio"
"fmt"
"io"
"io/ioutil"
"strings"
"sync"
"time"
@ -13,11 +12,12 @@ import (
// pname used by pmux itself for logging.
const pmuxPName = "pmux"
// characters used to denote different kinds of logs
// Characters used to denote different kinds of logs in the default Pmux
// configuration.
const (
logSepStdout = '›'
logSepStderr = '»'
logSepSys = '~'
LogSepStdout = '›'
LogSepStderr = '»'
LogSepSys = '~'
)
// Logger is used by RunProcess to log process details in realtime. You can use
@ -25,20 +25,26 @@ const (
type Logger interface {
Println(string)
Printf(string, ...interface{})
Close() error
}
// NullLogger is an implementation of Logger which doesn't do anything.
type NullLogger struct{}
func (*NullLogger) Println(string) {}
func (*NullLogger) Printf(string, ...interface{}) {}
var _ Logger = NullLogger{}
func (NullLogger) Println(string) {}
func (NullLogger) Printf(string, ...interface{}) {}
func (NullLogger) Close() error { return nil }
// PlainLogger implements Logger by writing each line directly to the given
// io.Writer as-is.
type PlainLogger struct {
io.Writer
io.WriteCloser
}
var _ Logger = PlainLogger{}
func (l PlainLogger) Println(line string) {
fmt.Fprintln(l, line)
}
@ -47,7 +53,15 @@ func (l PlainLogger) Printf(str string, args ...interface{}) {
fmt.Fprintf(l, str, args...)
}
type logger struct {
func (l PlainLogger) Close() error {
return l.WriteCloser.Close()
}
// PmuxLogger is used by the pmux process itself for logging. It can prefix log
// lines with a timestamp, the name of the process being logged, and a custom
// separator in front of the log line to help delineate one kind of log from
// another.
type PmuxLogger struct {
timeFmt string
l *sync.Mutex
@ -61,16 +75,21 @@ type logger struct {
sep rune
}
func newLogger(
out io.Writer,
sep rune,
timeFmt string,
) *logger {
var _ Logger = (*PmuxLogger)(nil)
pname := pmuxPName
maxPNameLen := uint64(len(pname))
// NewPmuxLogger returns a PmuxLogger which will write lines to the given
// io.Writer, separating metadata from the line itself using the given
// separator.
//
// If timeFmt is not empty string then the timestamp of each line will be output
// using that format.
func NewPmuxLogger(out io.Writer, sep rune, timeFmt string) *PmuxLogger {
var (
pname = pmuxPName
maxPNameLen = uint64(len(pname))
)
l := &logger{
return &PmuxLogger{
timeFmt: timeFmt,
maxPNameLen: &maxPNameLen,
l: new(sync.Mutex),
@ -79,17 +98,23 @@ func newLogger(
pname: pname,
sep: sep,
}
return l
}
func (l *logger) withSep(sep rune) *logger {
// WithSep returns a copy of the PmuxLogger which uses the given separator. The
// original PmuxLogger will continue to function normally.
func (l *PmuxLogger) WithSep(sep rune) *PmuxLogger {
l2 := *l
l2.sep = sep
return &l2
}
func (l *logger) withPName(pname string) *logger {
// WithProcessName returns a copy of the PmuxLogger which will prefix log lines
// with the given process name.
//
// All PmuxLoggers which are spawned using a With* method, including the
// original, will left pad their process name to the length of the longest
// process name in the group.
func (l *PmuxLogger) WithProcessName(pname string) *PmuxLogger {
l2 := *l
l2.pname = pname
@ -103,27 +128,26 @@ func (l *logger) withPName(pname string) *logger {
return &l2
}
func (l *logger) Close() {
// Close flushes all buffered log data, and sets the logger to discard all
// future print calls.
//
// PmuxLoggers created via With* methods should be each closed individually.
func (l *PmuxLogger) Close() error {
l.l.Lock()
defer l.l.Unlock()
l.outBuf.Flush()
if syncer, ok := l.out.(interface{ Sync() error }); ok {
_ = syncer.Sync()
} else if flusher, ok := l.out.(interface{ Flush() error }); ok {
_ = flusher.Flush()
}
err := l.outBuf.Flush()
// this generally shouldn't be necessary, but we could run into cases (e.g.
// during a force-kill) where further Prints are called after a Close. These
// should just do nothing.
l.out = ioutil.Discard
l.out = io.Discard
l.outBuf = bufio.NewWriter(l.out)
return err
}
func (l *logger) println(line string) {
func (l *PmuxLogger) println(line string) {
l.l.Lock()
defer l.l.Unlock()
@ -149,10 +173,10 @@ func (l *logger) println(line string) {
l.outBuf.Flush()
}
func (l *logger) Println(line string) {
func (l *PmuxLogger) Println(line string) {
l.println(line)
}
func (l *logger) Printf(msg string, args ...interface{}) {
func (l *PmuxLogger) Printf(msg string, args ...interface{}) {
l.Println(fmt.Sprintf(msg, args...))
}

38
pmuxlib/pmuxlib.go
View File

@ -22,31 +22,30 @@ type Config struct {
// a leftover zombie child process.
type Pmux struct {
processes map[string]*Process
sysLogger Logger
stdoutLogger, stderrLogger, sysLogger Logger
}
// NewPmux starts a Pmux with the given configuration.
func NewPmux(cfg Config, stdout, stderr io.Writer) *Pmux {
stdoutLogger := newLogger(stdout, logSepStdout, cfg.TimeFormat)
defer stdoutLogger.Close()
var (
stdoutLogger = NewPmuxLogger(stdout, LogSepStdout, cfg.TimeFormat)
stderrLogger = NewPmuxLogger(stderr, LogSepStderr, cfg.TimeFormat)
sysLogger = stderrLogger.WithSep(LogSepSys)
stderrLogger := newLogger(stderr, logSepStderr, cfg.TimeFormat)
defer stderrLogger.Close()
sysLogger := stderrLogger.withSep(logSepSys)
p := &Pmux{
p = &Pmux{
processes: map[string]*Process{},
stdoutLogger: stdoutLogger,
stderrLogger: stderrLogger,
sysLogger: sysLogger,
}
)
for name, cfgProc := range cfg.Processes {
stdoutLogger := stdoutLogger.withPName(name)
stderrLogger := stderrLogger.withPName(name)
sysLogger := sysLogger.withPName(name)
p.processes[name] = NewProcess(
cfgProc, stdoutLogger, stderrLogger, sysLogger,
)
cfgProc.StdoutLogger = stdoutLogger.WithProcessName(name)
cfgProc.StderrLogger = stderrLogger.WithProcessName(name)
cfgProc.SysLogger = sysLogger.WithProcessName(name)
p.processes[name] = NewProcess(cfgProc)
}
return p
@ -97,5 +96,14 @@ func (p *Pmux) Stop() {
wg.Wait()
}
if err := p.stdoutLogger.Close(); err != nil {
p.sysLogger.Printf("Closing stdout logger failed: %v", err)
}
if err := p.stderrLogger.Close(); err != nil {
p.sysLogger.Printf("Closing stderr logger failed: %v", err)
}
p.sysLogger.Println("exited gracefully, ciao!")
_ = p.sysLogger.Close()
}

44
pmuxlib/process.go
View File

@ -56,7 +56,12 @@ type ProcessConfig struct {
// Processes will not be shut down until all processes with a higher group
// number are already shut down. Processes with the same group number will
// be shut down simultaneously.
Group int
Group int `yaml:"group"`
// Where to send stdout, stderr log lines, and lines from pmux itself.
StdoutLogger Logger `yaml:"-"`
StderrLogger Logger `yaml:"-"`
SysLogger Logger `yaml:"-"`
}
func (cfg ProcessConfig) withDefaults() ProcessConfig {
@ -103,13 +108,7 @@ func sigProcessGroup(sysLogger Logger, proc *os.Process, sig syscall.Signal) {
//
// The stdout and stderr of the process will be written to the corresponding
// Loggers. Various runtime events will be written to the sysLogger.
func RunProcessOnce(
ctx context.Context,
stdoutLogger, stderrLogger, sysLogger Logger,
cfg ProcessConfig,
) (
int, error,
) {
func RunProcessOnce(ctx context.Context, cfg ProcessConfig) (int, error) {
cfg = cfg.withDefaults()
@ -169,8 +168,8 @@ func RunProcessOnce(
}
defer stderr.Close()
fwdOutPipe(stdoutLogger, stdout)
fwdOutPipe(stderrLogger, stderr)
fwdOutPipe(cfg.StdoutLogger, stdout)
fwdOutPipe(cfg.StderrLogger, stderr)
if err := cmd.Start(); err != nil {
return -1, fmt.Errorf("starting process: %w", err)
@ -182,14 +181,14 @@ func RunProcessOnce(
select {
case <-ctx.Done():
sigProcessGroup(sysLogger, proc, syscall.SIGINT)
sigProcessGroup(cfg.SysLogger, proc, syscall.SIGINT)
case <-stopCh:
return
}
select {
case <-time.After(cfg.SigKillWait):
sigProcessGroup(sysLogger, proc, syscall.SIGKILL)
sigProcessGroup(cfg.SysLogger, proc, syscall.SIGKILL)
case <-stopCh:
}
@ -225,21 +224,14 @@ func RunProcessOnce(
// Loggers. Various runtime events will be written to the sysLogger.
type Process struct {
cfg ProcessConfig
stdoutLogger, stderrLogger, sysLogger Logger
stopFn context.CancelFunc
doneCh chan struct{}
}
// NewProcess returns a new Process instance based on the given config.
func NewProcess(
cfg ProcessConfig, stdoutLogger, stderrLogger, sysLogger Logger,
) *Process {
func NewProcess(cfg ProcessConfig) *Process {
p := &Process{
cfg: cfg.withDefaults(),
stdoutLogger: stdoutLogger,
stderrLogger: stderrLogger,
sysLogger: sysLogger,
}
p.run()
return p
@ -261,18 +253,14 @@ func (p *Process) restartLoop(ctx context.Context) {
for {
start := time.Now()
exitCode, err := RunProcessOnce(
ctx,
p.stdoutLogger, p.stderrLogger, p.sysLogger,
p.cfg,
)
exitCode, err := RunProcessOnce(ctx, p.cfg)
took := time.Since(start)
// TODO check if error was due to StartAfterFunc, change the log if so.
if err != nil {
p.sysLogger.Printf("exited: %v", err)
p.cfg.SysLogger.Printf("exited: %v", err)
} else {
p.sysLogger.Printf("exit code: %d", exitCode)
p.cfg.SysLogger.Printf("exit code: %d", exitCode)
}
if err := ctx.Err(); err != nil {
@ -293,7 +281,7 @@ func (p *Process) restartLoop(ctx context.Context) {
wait = p.cfg.MaxWait
}
p.sysLogger.Printf("will restart process in %v", wait)
p.cfg.SysLogger.Printf("will restart process in %v", wait)
select {
case <-time.After(wait):