more robust lightning client

1 files changed, 85 insertions, 3 deletions

diff --git a/lib/ln.ts b/lib/ln.ts
index c4ab40fd..1e190c31 100644
--- a/lib/ln.ts
+++ b/lib/ln.ts
@@ -1,5 +1,87 @@
 import config from "$config";
 
-const { LightningClient } = (await import("@asoltys/clightning-client")).default;
-export default new LightningClient(config.lightning);
-export const lnb = new LightningClient(config.lightningb);
+const mod = (await import("@asoltys/clightning-client")).default;
+const { LightningClient } = mod as { LightningClient: any };
+
+class LightningUnavailableError extends Error {
+  code = "LIGHTNING_UNAVAILABLE" as const;
+  constructor(msg: string) {
+    super(msg);
+    this.name = "LightningUnavailableError";
+  }
+}
+
+function isUnavailable(e: any) {
+  const code = e?.code ?? e?.errno;
+  return code === "ENOENT" || code === 2 || code === "ECONNREFUSED";
+}
+
+function isSocketDied(e: any) {
+  const code = e?.code ?? e?.errno;
+  return code === "EPIPE" || code === "ECONNRESET" || code === "ENOENT" || code === 2;
+}
+
+function lightningProxy(rpcPath: string) {
+  let client: any = null;
+
+  let nextTryAt = 0;
+  let backoff = 250;
+  const maxBackoff = 5000;
+
+  function ensure() {
+    if (client) return client;
+
+    const now = Date.now();
+    if (now < nextTryAt) {
+      throw new LightningUnavailableError(`Lightning not ready at ${rpcPath}`);
+    }
+
+    try {
+      client = new LightningClient(rpcPath);
+      backoff = 250;
+      nextTryAt = 0;
+      return client;
+    } catch (e: any) {
+      nextTryAt = Date.now() + backoff;
+      backoff = Math.min(maxBackoff, Math.floor(backoff * 1.8));
+
+      if (isUnavailable(e)) {
+        throw new LightningUnavailableError(
+          `Lightning RPC unavailable at ${rpcPath} (${e?.code ?? e?.errno ?? "error"})`
+        );
+      }
+      throw e;
+    }
+  }
+
+  return new Proxy(
+    {},
+    {
+      get(_t, prop: string | symbol) {
+        if (prop === "toString") return () => "[LightningProxy]";
+        if (prop === Symbol.toStringTag) return "LightningProxy";
+
+        return async (...args: any[]) => {
+          const c = ensure();
+          const v = c[prop as any];
+
+          if (typeof v !== "function") return v;
+
+          try {
+            return await v.apply(c, args);
+          } catch (e: any) {
+            if (isSocketDied(e)) client = null;
+            throw e;
+          }
+        };
+      },
+    }
+  );
+}
+
+// exports preserved
+const ln = lightningProxy(config.lightning);
+export default ln;
+
+export const lnb = lightningProxy(config.lightningb);
+export { LightningUnavailableError };