Add first cut at a pool

master/proxy.go

@@ -0,0 +1,48 @@
+package main
+
+import (
+	"log"
+	"net/http"
+	"net/http/httputil"
+	"net/url"
+)
+
+// startProxy starts an HTTP reverse proxy that forwards requests to workers.
+// It acquires a worker from the pool for each request and releases it when done.
+func startProxy(listenAddr string, pool *WorkerPool) {
+	handler := http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		// Acquire a worker (blocks if none available)
+		workerAddr, ok := pool.Acquire()
+		if !ok {
+			http.Error(w, "Service unavailable", http.StatusServiceUnavailable)
+			return
+		}
+
+		// Ensure we release the worker when done
+		defer pool.Release(workerAddr)
+
+		// Create reverse proxy to the worker
+		targetURL, err := url.Parse("http://" + workerAddr)
+		if err != nil {
+			log.Printf("[proxy] Failed to parse worker URL %s: %v", workerAddr, err)
+			http.Error(w, "Internal server error", http.StatusInternalServerError)
+			return
+		}
+
+		proxy := httputil.NewSingleHostReverseProxy(targetURL)
+
+		// Custom error handler
+		proxy.ErrorHandler = func(w http.ResponseWriter, r *http.Request, err error) {
+			log.Printf("[proxy] Error proxying to %s: %v", workerAddr, err)
+			http.Error(w, "Bad gateway", http.StatusBadGateway)
+		}
+
+		log.Printf("[proxy] %s %s -> %s", r.Method, r.URL.Path, workerAddr)
+		proxy.ServeHTTP(w, r)
+	})
+
+	log.Printf("[proxy] Listening on %s", listenAddr)
+	if err := http.ListenAndServe(listenAddr, handler); err != nil {
+		log.Fatalf("[proxy] Failed to start: %v", err)
+	}
+}