init

src/session/registry.ts

@@ -0,0 +1,78 @@
+import crypto from "node:crypto";
+
+export type SessionBinding = {
+  conversationId: string;
+  sessionId: string;
+  lastUsedAt: number;
+};
+
+export type SessionContext = {
+  conversationId: string;
+  accessToken?: string;
+  projectId?: string;
+};
+
+export class SessionRegistry {
+  private readonly ttlMs: number;
+  private readonly bindings = new Map<string, SessionBinding>();
+
+  constructor(ttlSeconds: number) {
+    this.ttlMs = ttlSeconds * 1000;
+  }
+
+  upsert(context: SessionContext, sessionId: string): SessionBinding {
+    const binding: SessionBinding = {
+      conversationId: context.conversationId,
+      sessionId,
+      lastUsedAt: Date.now(),
+    };
+    this.bindings.set(this.makeKey(context), binding);
+    return binding;
+  }
+
+  get(context: SessionContext): SessionBinding | null {
+    const key = this.makeKey(context);
+    const binding = this.bindings.get(key);
+    if (!binding) {
+      return null;
+    }
+    if (Date.now() - binding.lastUsedAt > this.ttlMs) {
+      this.bindings.delete(key);
+      return null;
+    }
+    binding.lastUsedAt = Date.now();
+    return binding;
+  }
+
+  count(): number {
+    this.evictExpired();
+    return this.bindings.size;
+  }
+
+  evictExpired(): string[] {
+    const expired: string[] = [];
+    const now = Date.now();
+    for (const [key, binding] of this.bindings.entries()) {
+      if (now - binding.lastUsedAt > this.ttlMs) {
+        expired.push(binding.sessionId);
+        this.bindings.delete(key);
+      }
+    }
+    return expired;
+  }
+
+  private makeKey(context: SessionContext): string {
+    const digest = crypto
+      .createHash("sha256")
+      .update(
+        [
+          context.conversationId,
+          context.accessToken ?? "",
+          context.projectId ?? "",
+        ].join("|"),
+      )
+      .digest("hex");
+
+    return digest;
+  }
+}