Optimize resource usage in waveform generation and image cache
- Replace sleep-based polling in waveform generation with channel-based synchronization to reduce CPU usage and improve responsiveness - Add sync.Pool for audio buffers in waveform analysis to reduce memory allocations - Fix critical bug in ImageCache where struct field updates were not being persisted to the map, causing LRU tracking to fail - Optimize ImageCache evictOne() to use single pass instead of two separate iterations through all cache items - Upgrade read locks to write locks in ImageCache Get methods to ensure struct updates are properly saved
This commit is contained in:
Gianluca Boiano
+33
-18
@@ -51,11 +51,13 @@ func (i *ImageCache) SetWithTTL(key string, val image.Image, ttl time.Duration)
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i.mu.Lock()
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defer i.mu.Unlock()
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now := time.Now().Unix()
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if v, ok := i.cache[key]; ok {
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v.val = val
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v.ttl = ttl
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v.expiresAt = time.Now().Add(v.ttl).Unix()
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v.lastAccessed = time.Now().Unix()
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v.lastAccessed = now
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i.cache[key] = v // Update the map with modified struct
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return
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}
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if len(i.cache) == i.MaxSize {
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@@ -65,7 +67,7 @@ func (i *ImageCache) SetWithTTL(key string, val image.Image, ttl time.Duration)
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val: val,
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ttl: ttl,
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expiresAt: time.Now().Add(ttl).Unix(),
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lastAccessed: time.Now().Unix(),
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lastAccessed: now,
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}
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}
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@@ -86,14 +88,15 @@ func (i *ImageCache) Get(key string) (image.Image, error) {
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}
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func (i *ImageCache) GetResetTTL(key string, resetTTL bool) (image.Image, error) {
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i.mu.RLock()
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defer i.mu.RUnlock()
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i.mu.Lock()
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defer i.mu.Unlock()
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if v, ok := i.cache[key]; ok {
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v.lastAccessed = time.Now().Unix()
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if resetTTL {
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v.expiresAt = time.Now().Add(v.ttl).Unix()
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}
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i.cache[key] = v // Update the map with modified struct
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return v.val, nil
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}
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return nil, ErrNotFound
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@@ -101,26 +104,29 @@ func (i *ImageCache) GetResetTTL(key string, resetTTL bool) (image.Image, error)
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// Gets the image if it exists and extends TTL to time.Now + ttl iff the image would expire before then
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func (i *ImageCache) GetExtendTTL(key string, ttl time.Duration) (image.Image, error) {
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i.mu.RLock()
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defer i.mu.RUnlock()
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i.mu.Lock()
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defer i.mu.Unlock()
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if v, ok := i.cache[key]; ok {
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v.lastAccessed = time.Now().Unix()
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if v.expiresAt < time.Now().Add(ttl).Unix() {
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v.expiresAt = time.Now().Add(ttl).Unix()
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newExpiry := time.Now().Add(ttl).Unix()
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if v.expiresAt < newExpiry {
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v.expiresAt = newExpiry
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}
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i.cache[key] = v // Update the map with modified struct
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return v.val, nil
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}
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return nil, ErrNotFound
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}
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func (i *ImageCache) GetWithNewTTL(key string, newTtl time.Duration) (image.Image, error) {
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i.mu.RLock()
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defer i.mu.RUnlock()
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i.mu.Lock()
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defer i.mu.Unlock()
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if v, ok := i.cache[key]; ok {
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v.lastAccessed = time.Now().Unix()
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v.expiresAt = time.Now().Add(newTtl).Unix()
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v.ttl = newTtl
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i.cache[key] = v // Update the map with modified struct
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return v.val, nil
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}
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return nil, ErrNotFound
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@@ -137,24 +143,33 @@ func (i *ImageCache) Clear() {
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func (i *ImageCache) evictOne() {
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now := time.Now().Unix()
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var lruKey string
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lruTime := now
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lruTime := now + 1 // Initialize to future time so any item will be less
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var lruExpiredKey string
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lruExpiredTime := now
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lruExpiredTime := now + 1 // Initialize to future time
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hasExpired := false
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// Single pass through the cache to find both LRU expired and LRU items
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for k, v := range i.cache {
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if v.expiresAt < now && v.lastAccessed < lruExpiredTime {
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lruExpiredTime = v.lastAccessed
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lruExpiredKey = k
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if v.expiresAt < now {
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// This item is expired
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if v.lastAccessed < lruExpiredTime {
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lruExpiredTime = v.lastAccessed
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lruExpiredKey = k
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hasExpired = true
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}
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}
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// Track LRU regardless of expiration
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if v.lastAccessed < lruTime {
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lruTime = v.lastAccessed
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lruKey = k
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}
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}
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if lruExpiredTime < now {
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// deleting LRU expired item
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if hasExpired {
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// Prefer deleting LRU expired item
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delete(i.cache, lruExpiredKey)
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} else {
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// no expired items, delete LRU non-expired item
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// No expired items, delete LRU non-expired item
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delete(i.cache, lruKey)
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}
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}
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@@ -25,6 +25,13 @@ type WaveformImageGenerator struct {
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audioCache *AudioCache
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}
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// Buffer pool for waveform analysis to reduce allocations
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var audioBufferPool = sync.Pool{
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New: func() any {
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return &audio.IntBuffer{Data: make([]int, 4096)}
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},
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}
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type WaveformImage = image.NRGBA
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func NewWaveformImage() *WaveformImage {
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@@ -192,13 +199,19 @@ func (w *WaveformImageGenerator) StartWaveformGeneration(item *mediaprovider.Tra
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}
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// Start analyzing the converted wav file
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data := &waveformData{}
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data := &waveformData{notify: make(chan struct{}, 1)}
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go func() {
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err := analyzeWavFile(ctx, transcodeFile, data, item.Duration.Milliseconds(), func() bool { return wavConvertDone })
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if err != nil {
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job.setError(err)
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}
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data.done = true
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// Final notification that processing is complete
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select {
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case data.notify <- struct{}{}:
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default:
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}
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close(data.notify)
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}()
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// Start generating the waveform image
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@@ -216,6 +229,7 @@ type waveformData struct {
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progress int // first invalid index for Peak/RMS data
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done bool
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notify chan struct{} // signals when new data is available
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}
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func generateWaveformImage(ctx context.Context, data *waveformData, job *WaveformImageJob) {
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@@ -227,14 +241,18 @@ func generateWaveformImage(ctx context.Context, data *waveformData, job *Wavefor
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translucentColor := color.NRGBA{R: 255, G: 255, B: 255, A: 128}
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for x := range 1024 {
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for data.progress <= x {
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if data.done {
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return
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}
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if ctx.Err() != nil {
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// Wait for data to be available instead of polling
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for data.progress <= x && !data.done {
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select {
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case <-ctx.Done():
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return // expired
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case <-data.notify:
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// New data available or processing complete
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}
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time.Sleep(50 * time.Millisecond)
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}
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if data.progress <= x {
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return // done but data not available for this x
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}
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rmsPixels := int(data.RMS[x]) * centerY / 255
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@@ -282,7 +300,10 @@ func analyzeWavFile(ctx context.Context, transcodeFile string, data *waveformDat
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return err
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}
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buf := &audio.IntBuffer{Data: make([]int, 4096)}
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// Get buffer from pool to reduce allocations
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buf := audioBufferPool.Get().(*audio.IntBuffer)
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defer audioBufferPool.Put(buf)
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curChunk := 0
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chunkSamples := make([]float64, 0, samplesPerChunk)
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bytesPerSample := int64(2 * format.NumChannels) // 16-bit = 2 bytes per channel
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@@ -353,6 +374,11 @@ func analyzeWavFile(ctx context.Context, transcodeFile string, data *waveformDat
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}
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curChunk++
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data.progress = curChunk
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// Notify that new data is available (non-blocking)
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select {
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case data.notify <- struct{}{}:
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default:
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}
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chunkSamples = chunkSamples[:0]
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if curChunk >= 1024 {
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break
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@@ -367,6 +393,11 @@ func analyzeWavFile(ctx context.Context, transcodeFile string, data *waveformDat
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data.Peak[curChunk] = float64ToByte(peak)
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data.RMS[curChunk] = float64ToByte(rms)
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data.progress = curChunk + 1
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// Notify that final data is available (non-blocking)
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select {
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case data.notify <- struct{}{}:
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default:
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}
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}
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return nil
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