fix: use async fs operations to avoid blocking the main program loop

components/client/typescript/src/predicates.ts

@@ -1,4 +1,4 @@
-import * as fs from 'fs';
+import * as fs from 'fs/promises';
 import * as path from 'path';
 import { logger } from './util/logger';
 import {
@@ -17,17 +17,32 @@ const RegisteredPredicates = new Map<string, Predicate>();
 
 const CompiledPredicateSchema = TypeCompiler.Compile(PredicateSchema);
 
+// Async version of fs.existsSync
+async function pathExists(path: string): Promise<boolean> {
+  try {
+    await fs.access(path);
+    return true;
+  } catch (error) {
+    if ((error as NodeJS.ErrnoException).code === 'ENOENT') {
+      return false;
+    }
+    throw error; // Re-throw other errors (e.g., permission issues)
+  }
+}
+
 /**
  * Looks on disk and returns a map of registered Predicates, where the key is the predicate `name`
  * as defined by the user.
  */
-export function recallPersistedPredicatesFromDisk(basePath: string): Map<string, Predicate> {
+export async function recallPersistedPredicatesFromDisk(
+  basePath: string
+): Promise<Map<string, Predicate>> {
   RegisteredPredicates.clear();
   try {
-    if (!fs.existsSync(basePath)) return RegisteredPredicates;
-    for (const file of fs.readdirSync(basePath)) {
+    if (!(await pathExists(basePath))) return RegisteredPredicates;
+    for (const file of await fs.readdir(basePath)) {
       if (file.endsWith('.json')) {
-        const text = fs.readFileSync(path.join(basePath, file), 'utf-8');
+        const text = await fs.readFile(path.join(basePath, file), 'utf-8');
         const predicate = JSON.parse(text) as JSON;
         if (CompiledPredicateSchema.Check(predicate)) {
           logger.info(
@@ -44,11 +59,11 @@ export function recallPersistedPredicatesFromDisk(basePath: string): Map<string,
   return RegisteredPredicates;
 }
 
-export function savePredicateToDisk(basePath: string, predicate: Predicate) {
+export async function savePredicateToDisk(basePath: string, predicate: Predicate) {
   const predicatePath = `${basePath}/predicate-${encodeURIComponent(predicate.name)}.json`;
   try {
-    fs.mkdirSync(basePath, { recursive: true });
-    fs.writeFileSync(predicatePath, JSON.stringify(predicate, null, 2));
+    await fs.mkdir(basePath, { recursive: true });
+    await fs.writeFile(predicatePath, JSON.stringify(predicate, null, 2));
     logger.info(
       `ChainhookEventObserver persisted predicate '${predicate.name}' (${predicate.uuid}) to disk`
     );
@@ -60,13 +75,18 @@ export function savePredicateToDisk(basePath: string, predicate: Predicate) {
   }
 }
 
-function deletePredicateFromDisk(basePath: string, predicate: Predicate) {
+async function deletePredicateFromDisk(basePath: string, predicate: Predicate) {
   const predicatePath = `${basePath}/predicate-${encodeURIComponent(predicate.name)}.json`;
-  if (fs.existsSync(predicatePath)) {
-    fs.rmSync(predicatePath);
+  try {
+    await fs.rm(predicatePath);
     logger.info(
       `ChainhookEventObserver deleted predicate '${predicate.name}' (${predicate.uuid}) from disk`
     );
+  } catch (error: unknown) {
+    // ignore if the file doesn't exist
+    if ((error as NodeJS.ErrnoException).code !== 'ENOENT') {
+      logger.error(error, `Failed to delete predicate`);
+    }
   }
 }
 
@@ -165,7 +185,7 @@ async function registerPredicate(
     logger.info(
       `ChainhookEventObserver registered '${newPredicate.name}' predicate (${newPredicate.uuid})`
     );
-    savePredicateToDisk(observer.predicate_disk_file_path, newPredicate);
+    await savePredicateToDisk(observer.predicate_disk_file_path, newPredicate);
     RegisteredPredicates.set(newPredicate.name, newPredicate);
   } catch (error) {
     logger.error(error, `ChainhookEventObserver unable to register predicate`);
@@ -190,7 +210,7 @@ async function removePredicate(
       throwOnError: true,
     });
     logger.info(`ChainhookEventObserver removed predicate '${predicate.name}' (${predicate.uuid})`);
-    deletePredicateFromDisk(observer.predicate_disk_file_path, predicate);
+    await deletePredicateFromDisk(observer.predicate_disk_file_path, predicate);
   } catch (error) {
     logger.error(error, `ChainhookEventObserver unable to deregister predicate`);
   }
@@ -207,7 +227,7 @@ export async function registerAllPredicatesOnObserverReady(
     logger.info(`ChainhookEventObserver does not have predicates to register`);
     return;
   }
-  const diskPredicates = recallPersistedPredicatesFromDisk(observer.predicate_disk_file_path);
+  const diskPredicates = await recallPersistedPredicatesFromDisk(observer.predicate_disk_file_path);
   for (const predicate of predicates)
     await registerPredicate(predicate, diskPredicates, observer, chainhook);
 }
@@ -217,7 +237,7 @@ export async function removeAllPredicatesOnObserverClose(
   observer: EventObserverOptions,
   chainhook: ChainhookNodeOptions
 ) {
-  const diskPredicates = recallPersistedPredicatesFromDisk(observer.predicate_disk_file_path);
+  const diskPredicates = await recallPersistedPredicatesFromDisk(observer.predicate_disk_file_path);
   if (diskPredicates.size === 0) {
     logger.info(`ChainhookEventObserver does not have predicates to close`);
     return;

components/client/typescript/tests/predicates.test.ts

@@ -83,7 +83,7 @@ describe('predicates', () => {
     await server.start([testPredicate], async () => {});
 
     expect(fs.existsSync(`${observer.predicate_disk_file_path}/predicate-test.json`)).toBe(true);
-    const disk = recallPersistedPredicatesFromDisk(observer.predicate_disk_file_path);
+    const disk = await recallPersistedPredicatesFromDisk(observer.predicate_disk_file_path);
     const storedPredicate = disk.get('test');
     expect(storedPredicate).not.toBeUndefined();
     expect(storedPredicate?.name).toBe(testPredicate.name);
@@ -102,8 +102,8 @@ describe('predicates', () => {
   });
 
   describe('pre-stored', () => {
-    beforeEach(() => {
-      savePredicateToDisk(observer.predicate_disk_file_path, {
+    beforeEach(async () => {
+      await savePredicateToDisk(observer.predicate_disk_file_path, {
         uuid: 'e2777d77-473a-4c1d-9012-152deb36bf4c',
         name: 'test',
         version: 1,
@@ -164,7 +164,7 @@ describe('predicates', () => {
 
       mockAgent.assertNoPendingInterceptors();
       expect(fs.existsSync(`${observer.predicate_disk_file_path}/predicate-test.json`)).toBe(true);
-      const disk = recallPersistedPredicatesFromDisk(observer.predicate_disk_file_path);
+      const disk = await recallPersistedPredicatesFromDisk(observer.predicate_disk_file_path);
       const storedPredicate = disk.get('test');
       // Should have a different uuid
       expect(storedPredicate?.uuid).not.toBe('e2777d77-473a-4c1d-9012-152deb36bf4c');