feat: Add Redis upload cache for multi-replica deployments (#5724)

http/upload_cache_memory.go

@@ -0,0 +1,85 @@
+package fbhttp
+
+import (
+	"context"
+	"fmt"
+	"os"
+	"time"
+
+	"github.com/jellydator/ttlcache/v3"
+)
+
+const uploadCacheTTL = 3 * time.Minute
+
+// UploadCache is an interface for tracking active uploads.
+// Allows for different backends (e.g. in-memory or redis)
+// to support both single instance and multi replica deployments.
+type UploadCache interface {
+	// Register stores an upload with its expected file size
+	Register(filePath string, fileSize int64)
+
+	// Complete removes an upload from the cache
+	Complete(filePath string)
+
+	// GetLength returns the expected file size for an active upload
+	GetLength(filePath string) (int64, error)
+
+	// Touch refreshes the TTL for an active upload
+	Touch(filePath string)
+
+	// Close cleans up any resources
+	Close()
+}
+
+// memoryUploadCache is an upload cache for single replica deployments
+type memoryUploadCache struct {
+	cache *ttlcache.Cache[string, int64]
+}
+
+func newMemoryUploadCache() *memoryUploadCache {
+	cache := ttlcache.New[string, int64]()
+	cache.OnEviction(func(_ context.Context, reason ttlcache.EvictionReason, item *ttlcache.Item[string, int64]) {
+		if reason == ttlcache.EvictionReasonExpired {
+			fmt.Printf("deleting incomplete upload file: \"%s\"\n", item.Key())
+			os.Remove(item.Key())
+		}
+	})
+	go cache.Start()
+
+	return &memoryUploadCache{cache: cache}
+}
+
+func (c *memoryUploadCache) Register(filePath string, fileSize int64) {
+	c.cache.Set(filePath, fileSize, uploadCacheTTL)
+}
+
+func (c *memoryUploadCache) Complete(filePath string) {
+	c.cache.Delete(filePath)
+}
+
+func (c *memoryUploadCache) GetLength(filePath string) (int64, error) {
+	item := c.cache.Get(filePath)
+	if item == nil {
+		return 0, fmt.Errorf("no active upload found for the given path")
+	}
+	return item.Value(), nil
+}
+
+func (c *memoryUploadCache) Touch(filePath string) {
+	c.cache.Touch(filePath)
+}
+
+func (c *memoryUploadCache) Close() {
+	c.cache.Stop()
+}
+
+// NewUploadCache creates a new upload cache.
+// If redisURL is empty, an in-memory cache will be used (suitable for single instance deployments).
+// Otherwise, Redis will be used for the cache (suitable for multi-instance deployments).
+// The redisURL can include credentials, e.g. redis://user:pass@host:port
+func NewUploadCache(redisURL string) (UploadCache, error) {
+	if redisURL != "" {
+		return newRedisUploadCache(redisURL)
+	}
+	return newMemoryUploadCache(), nil
+}