Fixes #77 - settimout

SETTIMEOUT_LIMIT_FIX.md

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+# setTimeout Limit Fix for Pulse
+
+## Problem
+
+JavaScript's `setTimeout` function has a maximum delay value of `2^31 - 1` milliseconds (approximately 24.8 days). When a value larger than this is passed to `setTimeout`, the behavior becomes unpredictable and the timeout may fire immediately or not at all.
+
+In Pulse, when jobs are scheduled for dates beyond this limit, the original code would pass the raw time difference to `setTimeout`, causing unpredictable behavior for long-term scheduled jobs.
+
+## Solution
+
+The fix implemented in `src/utils/process-jobs.ts` adds a check for the setTimeout limit:
+
+```typescript
+// JavaScript's setTimeout has a maximum value of 2^31 - 1 milliseconds (approximately 24.8 days)
+// If the delay exceeds this limit, setTimeout behaves unpredictably
+const MAX_TIMEOUT = Math.pow(2, 31) - 1;
+
+if (runIn > MAX_TIMEOUT) {
+  // For jobs scheduled beyond the setTimeout limit, use a shorter timeout and re-check periodically
+  const checkInterval = Math.min(MAX_TIMEOUT, 24 * 60 * 60 * 1000); // Check every 24 hours or at the limit
+  debug('[%s:%s] nextRunAt exceeds setTimeout limit (%d > %d), scheduling periodic check in %d ms', 
+        job.attrs.name, job.attrs._id, runIn, MAX_TIMEOUT, checkInterval);
+
+  setTimeout(() => {
+    // Re-enqueue the job for processing, which will re-evaluate the timing
+    enqueueJobs(job);
+  }, checkInterval);
+} else {
+  debug('[%s:%s] nextRunAt is in the future, calling setTimeout(%d)', job.attrs.name, job.attrs._id, runIn);
+  setTimeout(jobProcessing, runIn);
+}
+```
+
+## How It Works
+
+1. **Check the delay**: Before calling `setTimeout`, we check if the delay exceeds the maximum safe value.
+
+2. **Periodic re-evaluation**: For jobs scheduled beyond the limit, instead of using the full delay, we schedule a periodic check (every 24 hours or at the maximum safe timeout value, whichever is smaller).
+
+3. **Re-enqueue**: When the periodic check fires, it re-enqueues the job for processing, which causes the timing to be re-evaluated. This continues until the job's scheduled time is within the safe setTimeout range.
+
+## Benefits
+
+- **Predictable behavior**: Jobs scheduled far in the future will now behave predictably
+- **No immediate execution**: Jobs won't accidentally fire immediately due to setTimeout overflow
+- **Efficient**: Uses the maximum safe timeout value to minimize the number of periodic checks
+- **Backward compatible**: Jobs scheduled within the 24.8-day limit continue to work exactly as before
+
+## Testing
+
+The fix includes comprehensive tests in `test/unit/setTimeout-limits.spec.ts`:
+
+- Unit tests that verify the setTimeout limit logic
+- Tests that confirm values exceeding the limit are handled correctly
+- Demonstration script showing the fix in action
+
+Run the tests:
+```bash
+npm test -- test/unit/setTimeout-limits.spec.ts
+```
+
+Run the demonstration:
+```bash
+npx tsx examples/setTimeout-limit-demo.ts
+```
+
+## Impact
+
+This fix ensures that Pulse can reliably handle jobs scheduled weeks, months, or even years in the future without the unpredictable behavior caused by JavaScript's setTimeout limitations.

examples/setTimeout-limit-demo.ts

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+/**
+ * Demonstration of the setTimeout limit fix in Pulse
+ * 
+ * This example shows how Pulse now handles jobs scheduled beyond
+ * JavaScript's setTimeout maximum value (2^31 - 1 milliseconds ≈ 24.8 days)
+ */
+
+import { Pulse } from '../src';
+import { MongoMemoryServer } from 'mongodb-memory-server';
+import { MongoClient } from 'mongodb';
+
+async function demonstrateSetTimeoutLimitFix() {
+  console.log('🚀 Demonstrating setTimeout limit fix in Pulse\n');
+
+  // Setup in-memory MongoDB
+  const mongod = await MongoMemoryServer.create();
+  const uri = mongod.getUri();
+  const mongo = await MongoClient.connect(uri);
+
+  // Create Pulse instance
+  const pulse = new Pulse({ mongo: mongo.db() });
+
+  // Define a simple job
+  pulse.define('futureJob', async (job) => {
+    console.log(`✅ Job executed: ${job.attrs.data?.message}`);
+    return 'completed';
+  });
+
+  // Constants
+  const MAX_TIMEOUT = Math.pow(2, 31) - 1;
+  const ONE_DAY_MS = 24 * 60 * 60 * 1000;
+  const TEN_DAYS_MS = 10 * ONE_DAY_MS;
+  const THIRTY_DAYS_MS = 30 * ONE_DAY_MS;
+  const ONE_YEAR_MS = 365 * ONE_DAY_MS;
+
+  console.log(`📊 setTimeout limits:`);
+  console.log(`   Maximum setTimeout value: ${MAX_TIMEOUT.toLocaleString()} ms (≈ ${(MAX_TIMEOUT / ONE_DAY_MS).toFixed(1)} days)`);
+  console.log(`   10 days: ${TEN_DAYS_MS.toLocaleString()} ms (within limit: ${TEN_DAYS_MS < MAX_TIMEOUT})`);
+  console.log(`   30 days: ${THIRTY_DAYS_MS.toLocaleString()} ms (within limit: ${THIRTY_DAYS_MS < MAX_TIMEOUT})`);
+  console.log(`   1 year: ${ONE_YEAR_MS.toLocaleString()} ms (within limit: ${ONE_YEAR_MS < MAX_TIMEOUT})\n`);
+
+  // Mock setTimeout to track calls
+  const originalSetTimeout = global.setTimeout;
+  const setTimeoutCalls: number[] = [];
+
+  global.setTimeout = ((callback: any, delay: number) => {
+    if (typeof delay === 'number') {
+      setTimeoutCalls.push(delay);
+      console.log(`⏰ setTimeout called with delay: ${delay.toLocaleString()} ms (within limit: ${delay <= MAX_TIMEOUT})`);
+    }
+    return originalSetTimeout(callback, Math.min(delay, 1000)); // Use short delay for demo
+  }) as any;
+
+  try {
+    // Start Pulse
+    await pulse.start();
+
+    console.log('📅 Scheduling jobs with different future dates:\n');
+
+    // Schedule job 10 days in the future (within setTimeout limit)
+    const tenDaysJob = pulse.create('futureJob', { message: 'Job scheduled 10 days ahead' });
+    tenDaysJob.schedule(new Date(Date.now() + TEN_DAYS_MS));
+    await tenDaysJob.save();
+    console.log('✓ Scheduled job 10 days in the future');
+
+    // Schedule job 30 days in the future (exceeds setTimeout limit)
+    const thirtyDaysJob = pulse.create('futureJob', { message: 'Job scheduled 30 days ahead' });
+    thirtyDaysJob.schedule(new Date(Date.now() + THIRTY_DAYS_MS));
+    await thirtyDaysJob.save();
+    console.log('✓ Scheduled job 30 days in the future');
+
+    // Schedule job 1 year in the future (far exceeds setTimeout limit)
+    const oneYearJob = pulse.create('futureJob', { message: 'Job scheduled 1 year ahead' });
+    oneYearJob.schedule(new Date(Date.now() + ONE_YEAR_MS));
+    await oneYearJob.save();
+    console.log('✓ Scheduled job 1 year in the future');
+
+    // Give Pulse time to process the jobs
+    await new Promise(resolve => setTimeout(resolve, 2000));
+
+    console.log('\n📈 setTimeout call analysis:');
+    console.log(`   Total setTimeout calls: ${setTimeoutCalls.length}`);
+
+    const validCalls = setTimeoutCalls.filter(delay => delay <= MAX_TIMEOUT);
+    const invalidCalls = setTimeoutCalls.filter(delay => delay > MAX_TIMEOUT);
+
+    console.log(`   Calls within limit: ${validCalls.length}`);
+    console.log(`   Calls exceeding limit: ${invalidCalls.length}`);
+
+    if (invalidCalls.length === 0) {
+      console.log('✅ SUCCESS: All setTimeout calls are within the safe limit!');
+    } else {
+      console.log('❌ ISSUE: Some setTimeout calls exceed the safe limit');
+      invalidCalls.forEach(delay => {
+        console.log(`      - ${delay.toLocaleString()} ms (${(delay / ONE_DAY_MS).toFixed(1)} days)`);
+      });
+    }
+
+  } finally {
+    // Cleanup
+    global.setTimeout = originalSetTimeout;
+    await pulse.stop();
+    await mongo.close();
+    await mongod.stop();
+  }
+}
+
+// Run the demonstration
+if (require.main === module) {
+  demonstrateSetTimeoutLimitFix()
+    .then(() => {
+      console.log('\n🎉 Demonstration completed!');
+      process.exit(0);
+    })
+    .catch((error) => {
+      console.error('❌ Error during demonstration:', error);
+      process.exit(1);
+    });
+}
+
+export { demonstrateSetTimeoutLimitFix };