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125 lines
2.9 KiB
Go
125 lines
2.9 KiB
Go
package logging
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import (
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"container/ring"
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"fmt"
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"sync"
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"github.com/google/uuid"
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"github.com/rs/zerolog"
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)
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// DefaultBufferSize is the number of log lines to keep in memory.
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const (
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DefaultBufferSize = 1000
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)
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var (
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broadcaster *LogBroadcaster
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broadcastMu sync.Once
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)
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// LogBroadcaster captures log writes, buffers them, and broadcasts them to subscribers.
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type LogBroadcaster struct {
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mu sync.RWMutex
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buffer *ring.Ring
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subscribers map[string]chan string
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}
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// GetBroadcaster returns the singleton broadcaster instance.
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func GetBroadcaster() *LogBroadcaster {
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broadcastMu.Do(func() {
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broadcaster = &LogBroadcaster{
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buffer: ring.New(DefaultBufferSize),
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subscribers: make(map[string]chan string),
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}
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})
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return broadcaster
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}
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// Write implements io.Writer. It writes to the internal buffer and notifies subscribers.
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func (b *LogBroadcaster) Write(p []byte) (n int, err error) {
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// Copy slice to avoid race conditions if p is reused
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msg := string(p)
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b.mu.Lock()
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defer b.mu.Unlock()
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// 1. Write to ring buffer
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b.buffer.Value = msg
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b.buffer = b.buffer.Next()
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// 2. Broadcast to subscribers
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for id, ch := range b.subscribers {
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select {
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case ch <- msg:
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// Sent successfully
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default:
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// Channel blocked, too slow consumer.
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// In a real production system we might drop the client,
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// here we just skip this message for them to avoid blocking writer.
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// Ideally we should warn or close their channel.
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fmt.Printf("logging: subscriber %s blocked, dropping message\n", id)
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}
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}
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return len(p), nil
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}
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// Subscribe adds a new subscriber and returns a channel of log lines
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// plus a snapshot of the current history.
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func (b *LogBroadcaster) Subscribe() (string, chan string, []string) {
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b.mu.Lock()
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defer b.mu.Unlock()
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id := uuid.NewString()
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ch := make(chan string, 1000) // Large buffer to prevent blocking
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b.subscribers[id] = ch
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// Generate history snapshot
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history := make([]string, 0, DefaultBufferSize)
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b.buffer.Do(func(p interface{}) {
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if p != nil {
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history = append(history, p.(string))
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}
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})
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return id, ch, history
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}
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// Unsubscribe removes a subscriber.
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func (b *LogBroadcaster) Unsubscribe(id string) {
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b.mu.Lock()
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defer b.mu.Unlock()
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if ch, ok := b.subscribers[id]; ok {
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close(ch)
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delete(b.subscribers, id)
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}
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}
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// GetHistory returns the current in-memory log log history.
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func (b *LogBroadcaster) GetHistory() []string {
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b.mu.RLock()
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defer b.mu.RUnlock()
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history := make([]string, 0, DefaultBufferSize)
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b.buffer.Do(func(p interface{}) {
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if p != nil {
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history = append(history, p.(string))
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}
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})
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return history
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}
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// SetGlobalLevel updates the global zerolog level at runtime.
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func SetGlobalLevel(level string) {
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mu.Lock()
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defer mu.Unlock()
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zerolog.SetGlobalLevel(parseLevel(level))
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}
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// GetGlobalLevel returns the current global level string.
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func GetGlobalLevel() string {
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return zerolog.GlobalLevel().String()
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}
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