♻️ refactor: split src into internal packages and cmd

internal/render/cache.go

@@ -0,0 +1,232 @@
+package render
+
+import (
+	"bytes"
+	"container/list"
+	"sync"
+	"sync/atomic"
+	"time"
+)
+
+type cacheKey struct {
+	setID           int
+	index           int
+	width           int
+	height          int
+	keepAspectRatio bool
+	tier            ColorTier
+}
+
+type cacheShard struct {
+	mu       sync.Mutex
+	maxBytes int64
+	size     int64
+	entries  map[cacheKey]*list.Element
+	order    *list.List
+}
+
+type Cache struct {
+	shards     []cacheShard
+	size       atomic.Int64
+	hits       atomic.Uint64
+	misses     atomic.Uint64
+	evictions  atomic.Uint64
+	rejections atomic.Uint64
+	renders    atomic.Uint64
+	renderNs   atomic.Uint64
+}
+
+type cacheEntry struct {
+	key   cacheKey
+	ascii []byte
+	cost  int64
+}
+
+func entryCost(_ cacheKey, ascii []byte) int64 {
+	return int64(cap(ascii)) + 160
+}
+
+func NewCache(maxBytes int64) *Cache {
+	if maxBytes <= 0 {
+		return nil
+	}
+	shardCount := int(min(int64(16), max(int64(1), maxBytes/(1<<20))))
+	cache := &Cache{shards: make([]cacheShard, shardCount)}
+	for i := range cache.shards {
+		cache.shards[i] = cacheShard{
+			maxBytes: maxBytes / int64(shardCount),
+			entries:  make(map[cacheKey]*list.Element),
+			order:    list.New(),
+		}
+	}
+	return cache
+}
+
+func (c *Cache) shard(key cacheKey) *cacheShard {
+	hash := uint64(key.setID)*0x9e3779b185ebca87 ^ uint64(key.index)*0xc2b2ae3d27d4eb4f
+	hash ^= uint64(key.width)<<32 | uint64(uint32(key.height))
+	hash ^= uint64(key.tier)<<1 | uint64(boolToInt(key.keepAspectRatio))
+	return &c.shards[hash%uint64(len(c.shards))]
+}
+
+func boolToInt(value bool) int {
+	if value {
+		return 1
+	}
+	return 0
+}
+
+func (c *Cache) get(key cacheKey) ([]byte, bool) {
+	if c == nil {
+		return nil, false
+	}
+	shard := c.shard(key)
+	shard.mu.Lock()
+	defer shard.mu.Unlock()
+	el, ok := shard.entries[key]
+	if !ok {
+		c.misses.Add(1)
+		return nil, false
+	}
+	c.hits.Add(1)
+	shard.order.MoveToBack(el)
+	return el.Value.(*cacheEntry).ascii, true
+}
+
+func (c *Cache) put(key cacheKey, ascii []byte) {
+	if c == nil {
+		return
+	}
+	shard := c.shard(key)
+	cost := entryCost(key, ascii)
+	if cost > shard.maxBytes {
+		c.rejections.Add(1)
+		return
+	}
+	shard.mu.Lock()
+	defer shard.mu.Unlock()
+	if _, ok := shard.entries[key]; ok {
+		return
+	}
+	shard.entries[key] = shard.order.PushBack(&cacheEntry{key: key, ascii: ascii, cost: cost})
+	shard.size += cost
+	c.size.Add(cost)
+	for shard.size > shard.maxBytes {
+		oldest := shard.order.Front()
+		shard.order.Remove(oldest)
+		evicted := oldest.Value.(*cacheEntry)
+		delete(shard.entries, evicted.key)
+		shard.size -= evicted.cost
+		c.size.Add(-evicted.cost)
+		c.evictions.Add(1)
+	}
+}
+
+type CacheStats struct {
+	SizeBytes  int64
+	Hits       uint64
+	Misses     uint64
+	Evictions  uint64
+	Rejections uint64
+	Renders    uint64
+	RenderTime time.Duration
+}
+
+func (c *Cache) Stats() CacheStats {
+	if c == nil {
+		return CacheStats{}
+	}
+	return CacheStats{
+		SizeBytes:  c.size.Load(),
+		Hits:       c.hits.Load(),
+		Misses:     c.misses.Load(),
+		Evictions:  c.evictions.Load(),
+		Rejections: c.rejections.Load(),
+		Renders:    c.renders.Load(),
+		RenderTime: time.Duration(c.renderNs.Load()),
+	}
+}
+
+type Renderer struct {
+	setID       int
+	colorFrames [][]byte
+	options     Options
+	rampLUT     *[101][]byte
+	cache       *Cache
+
+	inflightMu sync.Mutex
+	inflight   map[cacheKey]*renderCall
+}
+
+type renderCall struct {
+	done  chan struct{}
+	value []byte
+	err   error
+}
+
+func NewRenderer(setID int, colorFrames [][]byte, options Options, cache *Cache) *Renderer {
+	ramp := []rune(resolveCharset(options.Charset))
+	return &Renderer{
+		setID:       setID,
+		colorFrames: colorFrames,
+		options:     options,
+		rampLUT:     buildRampLUT(ramp, options),
+		cache:       cache,
+		inflight:    make(map[cacheKey]*renderCall),
+	}
+}
+
+func (r *Renderer) Render(index, width, height int, keepAspectRatio bool, tier ColorTier) ([]byte, error) {
+	key := cacheKey{r.setID, index, width, height, keepAspectRatio, tier}
+	if ascii, ok := r.cache.get(key); ok {
+		return ascii, nil
+	}
+
+	r.inflightMu.Lock()
+	if call, ok := r.inflight[key]; ok {
+		r.inflightMu.Unlock()
+		<-call.done
+		return call.value, call.err
+	}
+	call := &renderCall{done: make(chan struct{})}
+	r.inflight[key] = call
+	r.inflightMu.Unlock()
+	defer func() {
+		r.inflightMu.Lock()
+		delete(r.inflight, key)
+		r.inflightMu.Unlock()
+		close(call.done)
+	}()
+
+	if ascii, ok := r.cache.get(key); ok {
+		call.value = ascii
+		return ascii, nil
+	}
+
+	started := time.Now()
+	pix := getPixBuf(4 * width * height)
+	img, err := resizeFrame(r.colorFrames[index], pix, width, height, keepAspectRatio)
+	if err != nil {
+		putPixBuf(pix)
+		call.err = err
+		return nil, err
+	}
+	var ascii []byte
+	if tier == ColorTierNone {
+		ascii = frameToAscii(img, r.rampLUT)
+	} else {
+		ascii = frameToAnsi(img, r.rampLUT, tier)
+	}
+	putPixBuf(pix)
+
+	if r.cache != nil && cap(ascii) > len(ascii)+len(ascii)/4 {
+		ascii = bytes.Clone(ascii)
+	}
+	r.cache.put(key, ascii)
+	if r.cache != nil {
+		r.cache.renders.Add(1)
+		r.cache.renderNs.Add(uint64(time.Since(started)))
+	}
+	call.value = ascii
+	return ascii, nil
+}