Add concurrency limits and configuration options for SteamCache

- Introduced maxConcurrentRequests and maxRequestsPerClient fields in the Config struct to manage request limits.
- Updated the SteamCache implementation to utilize these new configuration options for controlling concurrent requests.
- Enhanced the ServeHTTP method to enforce global and per-client rate limiting using semaphores.
- Modified the root command to accept new flags for configuring concurrency limits via command-line arguments.
- Updated tests to reflect changes in the SteamCache initialization and request handling logic.

config/config.go

@@ -11,6 +11,10 @@ type Config struct {
 	// Server configuration
 	ListenAddress string `yaml:"listen_address" default:":80"`
 
+	// Concurrency limits
+	MaxConcurrentRequests int64 `yaml:"max_concurrent_requests" default:"200"`
+	MaxRequestsPerClient  int64 `yaml:"max_requests_per_client" default:"5"`
+
 	// Cache configuration
 	Cache CacheConfig `yaml:"cache"`
 
@@ -65,6 +69,12 @@ func LoadConfig(configPath string) (*Config, error) {
 	if config.ListenAddress == "" {
 		config.ListenAddress = ":80"
 	}
+	if config.MaxConcurrentRequests == 0 {
+		config.MaxConcurrentRequests = 50
+	}
+	if config.MaxRequestsPerClient == 0 {
+		config.MaxRequestsPerClient = 3
+	}
 	if config.Cache.Memory.Size == "" {
 		config.Cache.Memory.Size = "0"
 	}
@@ -88,16 +98,18 @@ func SaveDefaultConfig(configPath string) error {
 	}
 
 	defaultConfig := Config{
-		ListenAddress: ":80",
+		ListenAddress:         ":80",
+		MaxConcurrentRequests: 50, // Reduced for home user (less concurrent load)
+		MaxRequestsPerClient:  3,  // Reduced for home user (more conservative per client)
 		Cache: CacheConfig{
 			Memory: MemoryConfig{
-				Size:        "1GB",
+				Size:        "1GB", // Recommended for systems that can spare 1GB RAM for caching
 				GCAlgorithm: "lru",
 			},
 			Disk: DiskConfig{
-				Size:        "10GB",
+				Size:        "1TB", // Large HDD cache for home user
 				Path:        "./disk",
-				GCAlgorithm: "hybrid",
+				GCAlgorithm: "lru", // Better for gaming patterns (keeps recently played games)
 			},
 		},
 		Upstream: "",