perf: introduce a terraform template/dynamic parameter render cache on prebuilds path #21201
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,214 @@ | ||
| package dynamicparameters | ||
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| import ( | ||
| "context" | ||
| "fmt" | ||
| "sort" | ||
| "sync" | ||
| "time" | ||
|
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| "github.com/cespare/xxhash/v2" | ||
| "github.com/google/uuid" | ||
| "github.com/prometheus/client_golang/prometheus" | ||
|
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| "github.com/coder/preview" | ||
| "github.com/coder/quartz" | ||
| ) | ||
|
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| // RenderCacheImpl is a simple in-memory cache for preview.Preview results. | ||
| // It caches based on (templateVersionID, ownerID, parameterValues). | ||
| type RenderCacheImpl struct { | ||
| mu sync.RWMutex | ||
| entries map[cacheKey]*cacheEntry | ||
|
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| // Metrics (optional) | ||
| cacheHits prometheus.Counter | ||
| cacheMisses prometheus.Counter | ||
| cacheSize prometheus.Gauge | ||
|
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| // TTL cleanup | ||
| clock quartz.Clock | ||
| ttl time.Duration | ||
| stopOnce sync.Once | ||
| stopCh chan struct{} | ||
| doneCh chan struct{} | ||
| } | ||
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| type cacheEntry struct { | ||
| output *preview.Output | ||
| timestamp time.Time | ||
| } | ||
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| type cacheKey struct { | ||
| templateVersionID uuid.UUID | ||
| ownerID uuid.UUID | ||
| parameterHash uint64 | ||
| } | ||
|
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| // NewRenderCache creates a new render cache with a default TTL of 1 hour. | ||
| func NewRenderCache() *RenderCacheImpl { | ||
| return newCache(quartz.NewReal(), time.Hour, nil, nil, nil) | ||
| } | ||
|
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| // NewRenderCacheWithMetrics creates a new render cache with Prometheus metrics. | ||
| func NewRenderCacheWithMetrics(cacheHits, cacheMisses prometheus.Counter, cacheSize prometheus.Gauge) *RenderCacheImpl { | ||
| return newCache(quartz.NewReal(), time.Hour, cacheHits, cacheMisses, cacheSize) | ||
| } | ||
|
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| func newCache(clock quartz.Clock, ttl time.Duration, cacheHits, cacheMisses prometheus.Counter, cacheSize prometheus.Gauge) *RenderCacheImpl { | ||
| c := &RenderCacheImpl{ | ||
| entries: make(map[cacheKey]*cacheEntry), | ||
| clock: clock, | ||
| cacheHits: cacheHits, | ||
| cacheMisses: cacheMisses, | ||
| cacheSize: cacheSize, | ||
| ttl: ttl, | ||
| stopCh: make(chan struct{}), | ||
| doneCh: make(chan struct{}), | ||
| } | ||
|
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| // Start cleanup goroutine | ||
| go c.cleanupLoop(context.Background()) | ||
|
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| return c | ||
| } | ||
|
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| // NewRenderCacheForTest creates a new render cache for testing purposes. | ||
| func NewRenderCacheForTest() *RenderCacheImpl { | ||
| return NewRenderCache() | ||
| } | ||
|
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| // Close stops the cleanup goroutine and waits for it to finish. | ||
| func (c *RenderCacheImpl) Close() { | ||
| c.stopOnce.Do(func() { | ||
| close(c.stopCh) | ||
| <-c.doneCh | ||
| }) | ||
| } | ||
|
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| func (c *RenderCacheImpl) get(templateVersionID, ownerID uuid.UUID, parameters map[string]string) (*preview.Output, bool) { | ||
| key := makeKey(templateVersionID, ownerID, parameters) | ||
| c.mu.RLock() | ||
| entry, ok := c.entries[key] | ||
| c.mu.RUnlock() | ||
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| if !ok { | ||
| // Record miss | ||
| if c.cacheMisses != nil { | ||
| c.cacheMisses.Inc() | ||
| } | ||
| return nil, false | ||
| } | ||
|
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| // Check if entry has expired | ||
| if c.clock.Since(entry.timestamp) > c.ttl { | ||
| // Expired entry, treat as miss | ||
| if c.cacheMisses != nil { | ||
| c.cacheMisses.Inc() | ||
| } | ||
| return nil, false | ||
| } | ||
|
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| // Record hit and refresh timestamp | ||
| if c.cacheHits != nil { | ||
| c.cacheHits.Inc() | ||
| } | ||
|
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| // Refresh timestamp on hit to keep frequently accessed entries alive | ||
| c.mu.Lock() | ||
| entry.timestamp = c.clock.Now() | ||
| c.mu.Unlock() | ||
|
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| return entry.output, true | ||
| } | ||
|
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| func (c *RenderCacheImpl) put(templateVersionID, ownerID uuid.UUID, parameters map[string]string, output *preview.Output) { | ||
| key := makeKey(templateVersionID, ownerID, parameters) | ||
| c.mu.Lock() | ||
| defer c.mu.Unlock() | ||
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| c.entries[key] = &cacheEntry{ | ||
| output: output, | ||
| timestamp: c.clock.Now(), | ||
| } | ||
|
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| // Update cache size metric | ||
| if c.cacheSize != nil { | ||
| c.cacheSize.Set(float64(len(c.entries))) | ||
| } | ||
| } | ||
|
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| func makeKey(templateVersionID, ownerID uuid.UUID, parameters map[string]string) cacheKey { | ||
| return cacheKey{ | ||
| templateVersionID: templateVersionID, | ||
| ownerID: ownerID, | ||
| parameterHash: hashParameters(parameters), | ||
| } | ||
| } | ||
|
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| // hashParameters creates a deterministic hash of the parameter map. | ||
| func hashParameters(params map[string]string) uint64 { | ||
| if len(params) == 0 { | ||
| return 0 | ||
| } | ||
|
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| // Sort keys for deterministic hashing | ||
| keys := make([]string, 0, len(params)) | ||
| for k := range params { | ||
| keys = append(keys, k) | ||
| } | ||
| sort.Strings(keys) | ||
|
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| // Hash the sorted key-value pairs | ||
| var b string | ||
| for _, k := range keys { | ||
| b += fmt.Sprintf("%s:%s,", k, params[k]) | ||
| } | ||
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| return xxhash.Sum64String(b) | ||
| } | ||
|
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| // cleanupLoop runs periodically to remove expired cache entries. | ||
| func (c *RenderCacheImpl) cleanupLoop(ctx context.Context) { | ||
| defer close(c.doneCh) | ||
|
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| // Run cleanup every 15 minutes | ||
| cleanupFunc := func() error { | ||
| c.cleanup() | ||
| return nil | ||
| } | ||
|
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| // Run once immediately | ||
| _ = cleanupFunc() | ||
|
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| // Create a cancellable context for the ticker | ||
| tickerCtx, cancel := context.WithCancel(ctx) | ||
| defer cancel() | ||
|
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| // Create ticker for periodic cleanup | ||
| tkr := c.clock.TickerFunc(tickerCtx, 15*time.Minute, cleanupFunc, "render-cache-cleanup") | ||
|
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| // Wait for stop signal | ||
| <-c.stopCh | ||
| cancel() | ||
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| _ = tkr.Wait() | ||
| } | ||
|
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| // cleanup removes expired entries from the cache. | ||
| func (c *RenderCacheImpl) cleanup() { | ||
| c.mu.Lock() | ||
| defer c.mu.Unlock() | ||
|
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| now := c.clock.Now() | ||
| for key, entry := range c.entries { | ||
| if now.Sub(entry.timestamp) > c.ttl { | ||
| delete(c.entries, key) | ||
| } | ||
| } | ||
|
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| // Update cache size metric after cleanup | ||
| if c.cacheSize != nil { | ||
| c.cacheSize.Set(float64(len(c.entries))) | ||
| } | ||
| } | ||
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The pattern we use other places is we keep the metrics on the
RenderCacheImpl. Then callcache.Register(prometheusregistry)from outside. Or just pass in the prometheus registry toNew.If the registry is
nil, like in tests, just don't attach the metrics.