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|
package logger
import (
"fmt"
"sync"
)
type stdMsg struct {
level LogLevel
msg string
}
type jsonMsg []byte
func (m jsonMsg) Level() LogLevel {
return 0
}
func (m jsonMsg) String() string {
return string(m)
}
type LogMsg interface {
Level() LogLevel
fmt.Stringer
}
func (m stdMsg) Level() LogLevel {
return m.level
}
func (m stdMsg) String() string {
return m.msg
}
var (
logMessageC = make(chan LogMsg)
addSystemC = make(chan LogSystem)
flushC = make(chan chan struct{})
resetC = make(chan chan struct{})
)
func init() {
go dispatchLoop()
}
// each system can buffer this many messages before
// blocking incoming log messages.
const sysBufferSize = 500
func dispatchLoop() {
var (
systems []LogSystem
systemIn []chan LogMsg
systemWG sync.WaitGroup
)
bootSystem := func(sys LogSystem) {
in := make(chan LogMsg, sysBufferSize)
systemIn = append(systemIn, in)
systemWG.Add(1)
go sysLoop(sys, in, &systemWG)
}
for {
select {
case msg := <-logMessageC:
for _, c := range systemIn {
c <- msg
}
case sys := <-addSystemC:
systems = append(systems, sys)
bootSystem(sys)
case waiter := <-resetC:
// reset means terminate all systems
for _, c := range systemIn {
close(c)
}
systems = nil
systemIn = nil
systemWG.Wait()
close(waiter)
case waiter := <-flushC:
// flush means reboot all systems
for _, c := range systemIn {
close(c)
}
systemIn = nil
systemWG.Wait()
for _, sys := range systems {
bootSystem(sys)
}
close(waiter)
}
}
}
func sysLoop(sys LogSystem, in <-chan LogMsg, wg *sync.WaitGroup) {
for msg := range in {
sys.LogPrint(msg)
}
wg.Done()
}
// Reset removes all active log systems.
// It blocks until all current messages have been delivered.
func Reset() {
waiter := make(chan struct{})
resetC <- waiter
<-waiter
}
// Flush waits until all current log messages have been dispatched to
// the active log systems.
func Flush() {
waiter := make(chan struct{})
flushC <- waiter
<-waiter
}
// AddLogSystem starts printing messages to the given LogSystem.
func AddLogSystem(sys LogSystem) {
addSystemC <- sys
}
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