Merge pull request #377 from kleros/refactor/lockfile

refactor/lockfile

relayer-cli/src/utils/lock.test.ts

@@ -0,0 +1,84 @@
+import { claimLock, getLockFilePath, LockfileExistsError, releaseLock } from "./lock";
+
+describe("Lock", () => {
+  describe("getLockFilePath", () => {
+    it("should return the lock file path for a given network and chain id", () => {
+      const network = "mainnet";
+      const chainId = 1;
+
+      const result = getLockFilePath(network, chainId);
+      expect(result).toBe("./state/mainnet_1.pid");
+    });
+
+    it("should ensure the network name is lowercase", () => {
+      const network = "MAINNET";
+      const chainId = 1;
+
+      const result = getLockFilePath(network, chainId);
+      expect(result).toBe("./state/mainnet_1.pid");
+    });
+  });
+
+  describe("claimLock", () => {
+    const network = "mainnet";
+    const chainId = 1;
+    const expectedLockFilePath = getLockFilePath(network, chainId);
+
+    it("should throw an error if the lockfile already exists", () => {
+      const deps = {
+        fileExistsFn: jest.fn().mockReturnValue(true),
+      };
+
+      expect(() => claimLock(network, chainId, deps)).toThrow(LockfileExistsError);
+    });
+
+    it("should write a file with the PID if none exists", () => {
+      const deps = {
+        fileExistsFn: jest.fn().mockReturnValue(false),
+        writeFileFn: jest.fn(),
+      };
+
+      claimLock(network, chainId, deps);
+
+      expect(deps.fileExistsFn).toHaveBeenCalledTimes(1);
+      expect(deps.writeFileFn).toHaveBeenCalledTimes(1);
+
+      const [path, pid] = deps.writeFileFn.mock.calls[0];
+      expect(path).toBe(expectedLockFilePath);
+      expect(pid).toBe(process.pid.toString());
+    });
+  });
+
+  describe("releaseLock", () => {
+    const network = "mainnet";
+    const chainId = 1;
+    const expectedLockFilePath = getLockFilePath(network, chainId);
+
+    it("should remove the lockfile if it exists", () => {
+      const deps = {
+        fileExistsFn: jest.fn().mockReturnValue(true),
+        unlinkFileFn: jest.fn(),
+      };
+
+      releaseLock(network, chainId, deps);
+
+      expect(deps.fileExistsFn).toHaveBeenCalledTimes(1);
+      expect(deps.unlinkFileFn).toHaveBeenCalledTimes(1);
+
+      const [path] = deps.unlinkFileFn.mock.calls[0];
+      expect(path).toBe(expectedLockFilePath);
+    });
+
+    it("should do nothing if the file does not exist", () => {
+      const deps = {
+        fileExistsFn: jest.fn().mockReturnValue(false),
+        unlinkFileFn: jest.fn(),
+      };
+
+      releaseLock(network, chainId, deps);
+
+      expect(deps.fileExistsFn).toHaveBeenCalledTimes(1);
+      expect(deps.unlinkFileFn).not.toHaveBeenCalled();
+    });
+  });
+});

relayer-cli/src/utils/lock.ts

@@ -0,0 +1,85 @@
+import fs from "fs";
+
+/**
+ * Returns the lock file path for a given network and chain id
+ *
+ * @param network - The network name
+ * @param chainId - The numerical identifier of the chain
+ * @returns The lock file path
+ *
+ * @example
+ * getLockFilePath('goerli', 1); // './state/goerli_1.pid'
+ */
+export function getLockFilePath(network: string, chainId: number) {
+  return `./state/${network.toLowerCase()}_${chainId}.pid`;
+}
+
+export class LockfileExistsError extends Error {
+  constructor(path: string) {
+    super();
+    this.message = `The application tried to claim the lockfile ${path} but it already exists. Please ensure no other instance is running and delete the lockfile before starting a new one.`;
+    this.name = "OnlyOneProcessError";
+  }
+}
+
+type ClaimLockDependencies = {
+  fileExistsFn?: typeof fs.existsSync;
+  writeFileFn?: typeof fs.writeFileSync;
+};
+
+/**
+ * Ensures there is only one process running at the same time for a given lock file.
+ *
+ * If the lock file exists, thrown an error. If it does not exists, creates it with the current process id.
+ *
+ * @param network - The network name
+ * @param chain - The chain id
+ * @param dependencies - FS methods to be used
+ *
+ * @example
+ * claimLock('/opt/app/lock.pid');
+ */
+export function claimLock(
+  network: string,
+  chain: number,
+  dependencies: ClaimLockDependencies = {
+    fileExistsFn: fs.existsSync,
+    writeFileFn: fs.writeFileSync,
+  }
+) {
+  const path = getLockFilePath(network, chain);
+  const { fileExistsFn, writeFileFn } = dependencies;
+
+  if (fileExistsFn(path)) throw new LockfileExistsError(path);
+  writeFileFn(path, process.pid.toString(), { encoding: "utf8" });
+}
+
+type ReleaseLockDependencies = {
+  fileExistsFn?: typeof fs.existsSync;
+  unlinkFileFn?: typeof fs.unlinkSync;
+};
+
+/**
+ * Ensures the lock file is removed
+ *
+ * @param network - The network name
+ * @param chainId - The numerical identifier of the chain
+ * @param dependencies - FS methods to be used
+ *
+ * @example
+ * releaseLock('/opt/app/lock.pid');
+ */
+export function releaseLock(
+  network: string,
+  chain: number,
+  dependencies: ReleaseLockDependencies = {
+    fileExistsFn: fs.existsSync,
+    unlinkFileFn: fs.unlinkSync,
+  }
+) {
+  const { fileExistsFn, unlinkFileFn } = dependencies;
+  const path = getLockFilePath(network, chain);
+
+  if (!fileExistsFn(path)) return;
+  unlinkFileFn(path);
+}

relayer-cli/src/utils/relayerHelpers.ts

@@ -1,14 +1,9 @@
 import * as fs from "fs";
+import { claimLock, releaseLock } from "./lock";
 import ShutdownManager from "./shutdownManager";
 
 async function initialize(chainId: number, network: string): Promise<number> {
-  const lockFileName = "./state/" + network + "_" + chainId + ".pid";
-
-  if (fs.existsSync(lockFileName)) {
-    console.log("Skipping chain with process already running, delete pid file to force", chainId);
-    throw new Error("Already running");
-  }
-  fs.writeFileSync(lockFileName, process.pid.toString(), { encoding: "utf8" });
+  claimLock(network, chainId);
 
   // STATE_DIR is absolute path of the directory where the state files are stored
   // STATE_DIR must have trailing slash
@@ -39,10 +34,7 @@ async function updateStateFile(chainId: number, createdTimestamp: number, nonceF
   };
   fs.writeFileSync(chain_state_file, JSON.stringify(json), { encoding: "utf8" });
 
-  const lockFileName = "./state/" + network + "_" + chainId + ".pid";
-  if (fs.existsSync(lockFileName)) {
-    fs.unlinkSync(lockFileName);
-  }
+  releaseLock(network, chainId);
 }
 
 async function setupExitHandlers(chainId: number, shutdownManager: ShutdownManager, network: string) {