Hyrex provides automatic retry mechanisms to handle transient failures and ensure reliable task execution.

​
Basic Retry Configuration

Configure retries using the maxRetries option: 
import { HyrexRegistry } from '@hyrex/hyrex';

const hy = new HyrexRegistry();

const resilientTask = hy.task({
    name: 'resilientTask',
    config: {
        maxRetries: 3  // Retry up to 3 times on failure (0-10)
    },
    func: async (data) => {
        // Task that might fail transiently
        const result = await unreliableService.call(data);
        return result;
    }
});

​
Default Behavior

  • Default retries: 3 attempts (configurable 0-10)
  • Retry trigger: Any thrown exception
  • Success condition: Task returns without throwing
  • Backoff strategy: Exponential backoff (built-in)

​
Exponential Backoff

The TypeScript SDK implements exponential backoff automatically:
  • First 5 failures: No delay (offset period)
  • After offset: 1.5s, 3s, 4.5s, 6s… up to 15s max
  • Backoff resets on successful execution
// Task with retries will automatically use exponential backoff
const apiTask = hy.task({
    name: 'apiTask',
    config: {
        maxRetries: 5,
        timeoutSeconds: 30
    },
    func: async (data) => {
        // Failures will retry with increasing delays
        const response = await externalAPI.post(data);
        return response.data;
    }
});

​
Retry Patterns

​
Conditional Retries

Control which errors trigger retries: 
class RetryableError extends Error {}
class PermanentError extends Error {}

const smartTask = hy.task({
    name: 'smartTask',
    config: {
        maxRetries: 3
    },
    func: async (data) => {
        try {
            return await riskyOperation(data);
        } catch (error: any) {
            if (error.code === 'RATE_LIMIT') {
                // This will retry with backoff
                throw new RetryableError('Rate limited, will retry');
            } else if (error.code === 'INVALID_INPUT') {
                // This will still retry (but probably fail again)
                // Consider returning an error instead
                throw new PermanentError('Invalid input, retry won't help');
            }
            // Unknown errors also retry
            throw error;
        }
    }
});

​
Return vs Throw

Control retry behavior with return values: 
const flexibleTask = hy.task({
    name: 'flexibleTask',
    config: {
        maxRetries: 3
    },
    func: async (data) => {
        try {
            const result = await operation(data);
            return { success: true, result };
        } catch (error) {
            // Option 1: Throw to trigger retry
            if (isTransient(error)) {
                throw error;  // Will retry
            }
            
            // Option 2: Return error to complete task
            return { 
                success: false, 
                error: error.message,
                permanent: true  // Won't retry
            };
        }
    }
});

​
Using Attempt Number

Access the current attempt for custom logic: 
import { getHyrexContext } from '@hyrex/hyrex';

const adaptiveTask = hy.task({
    name: 'adaptiveTask',
    config: {
        maxRetries: 3
    },
    func: async (data) => {
        const ctx = getHyrexContext();
        const attemptNumber = ctx.attemptNumber; // 0-based
        
        console.log(`Attempt ${attemptNumber + 1} of ${ctx.maxRetries + 1}`);
        
        // Use different strategies based on attempt
        if (attemptNumber === 0) {
            // First attempt - try primary service
            return await primaryService.process(data);
        } else if (attemptNumber < ctx.maxRetries) {
            // Intermediate attempts - try backup service
            return await backupService.process(data);
        } else {
            // Final attempt - use fallback
            return await fallbackProcessing(data);
        }
    }
});

​
Common Retry Scenarios

​
External API Calls

const apiCallTask = hy.task({
    name: 'apiCall',
    config: {
        maxRetries: 5,
        timeoutSeconds: 30
    },
    func: async ({ endpoint, payload }) => {
        try {
            const response = await fetch(endpoint, {
                method: 'POST',
                body: JSON.stringify(payload),
                headers: { 'Content-Type': 'application/json' }
            });
            
            if (!response.ok) {
                // Non-2xx status codes will retry
                throw new Error(`API error: ${response.status}`);
            }
            
            return await response.json();
        } catch (error) {
            // Network errors, timeouts, etc. will retry
            console.error(`API call failed: ${error.message}`);
            throw error;
        }
    }
});

​
Database Operations

const dbTask = hy.task({
    name: 'dbOperation',
    config: {
        maxRetries: 2,  // Fewer retries for DB operations
        queue: 'database'
    },
    func: async ({ query, params }) => {
        try {
            return await db.execute(query, params);
        } catch (error) {
            if (error.code === 'DEADLOCK_DETECTED') {
                // Deadlocks are retryable
                throw error;
            } else if (error.code === 'CONSTRAINT_VIOLATION') {
                // Don't retry constraint violations
                return { 
                    error: 'Constraint violation',
                    code: error.code,
                    failed: true
                };
            }
            throw error;
        }
    }
});

​
File Processing

const fileTask = hy.task({
    name: 'processFile',
    config: {
        maxRetries: 3,
        timeoutSeconds: 300  // 5 minutes
    },
    func: async ({ fileUrl }) => {
        const ctx = getHyrexContext();
        
        try {
            // Download file
            const file = await downloadFile(fileUrl);
            
            // Process file
            const result = await processFile(file);
            
            // Cleanup
            await cleanup(file);
            
            return result;
        } catch (error) {
            // Log attempt for debugging
            console.error(
                `File processing failed on attempt ${ctx.attemptNumber + 1}:`,
                error.message
            );
            
            // Always cleanup on failure
            await cleanup(file).catch(() => {});
            
            throw error;  // Retry
        }
    }
});

​
Best Practices

  1. Set Appropriate Retry Limits 
    // Quick operations: fewer retries
config: { maxRetries: 2 }

// External services: more retries
config: { maxRetries: 5 }

// Critical operations: max retries
config: { maxRetries: 10 }
  2. Consider Idempotency 
    const idempotentTask = hy.task({
    name: 'chargePayment',
    config: {
        maxRetries: 3,
        idempotencyKey: 'payment-123'  // Prevents duplicate charges
    },
    func: async (data) => {
        // Safe to retry without side effects
        return await paymentGateway.charge(data);
    }
});
  3. Log Retry Attempts 
    const loggingTask = hy.task({
    name: 'withLogging',
    config: { maxRetries: 3 },
    func: async (data) => {
        const ctx = getHyrexContext();
        
        if (ctx.attemptNumber > 0) {
            console.log(`Retry attempt ${ctx.attemptNumber} for task ${ctx.taskId}`);
        }
        
        try {
            return await operation(data);
        } catch (error) {
            console.error(`Attempt ${ctx.attemptNumber} failed:`, error);
            throw error;
        }
    }
});
  4. Handle Final Failures 
    const gracefulTask = hy.task({
    name: 'gracefulFailure',
    config: { maxRetries: 3 },
    func: async (data) => {
        const ctx = getHyrexContext();
        
        try {
            return await riskyOperation(data);
        } catch (error) {
            // On final attempt, return error state
            if (ctx.attemptNumber === ctx.maxRetries) {
                await notifyFailure(ctx.taskId, error);
                return {
                    status: 'failed_permanently',
                    error: error.message,
                    attempts: ctx.attemptNumber + 1
                };
            }
            throw error;  // Retry
        }
    }
});

​
Limitations

  • Max retries: Limited to 10 attempts
  • No custom backoff: Exponential backoff is built-in and not configurable
  • All exceptions retry: Cannot configure which error types retry
  • No retry delay control: Cannot set custom delays between retries

​
Next Steps

Tasks

Configure tasks with retries

Error Handling

Handle errors in tasks

Queues

Route retryable tasks