How to implement a caching mechanism with promises

26 Oct 2023

References

Caching is a technique used to store and retrieve expensive or time-consuming computations or data. By caching the results, you can significantly improve the performance and efficiency of your application. In this blog post, we will explore how to implement a caching mechanism using promises in JavaScript.

What are Promises?

Promises are a fundamental feature in JavaScript for handling asynchronous operations. They represent a value that may not be available yet but will be resolved in the future. Promises allow you to chain multiple asynchronous operations together, making your code more readable and easier to manage.

Implementing a Simple Cache

To implement a caching mechanism, we can leverage the power of promises. Here’s a simple example that demonstrates caching the result of an expensive computation using promises:

const cache = {};

function computeExpensiveValue(key) {
  return new Promise((resolve, reject) => {
    if (cache[key]) {
      resolve(cache[key]);
    } else {
      // Perform expensive computation
      const result = /* Your expensive computation logic */;
      cache[key] = result;
      resolve(result);
    }
  });
}

// Usage
computeExpensiveValue("myKey")
  .then((result) => {
    console.log(result);
  })
  .catch((error) => {
    console.error(error);
  });

In the above code, we maintain a cache object to store the results of expensive computations. When computeExpensiveValue is called with a key, it checks if the value is already in the cache. If it is, the promise is immediately resolved with the cached value. Otherwise, the expensive computation is performed, and the result is stored in the cache before resolving the promise.

Expanding the Caching Mechanism

The above example demonstrates a basic caching mechanism, but you can enhance it based on your requirements. Here are a few ideas to consider:

Expiration Time

You can introduce an expiration time for cached values to ensure that the data remains fresh. You can add a timestamp or duration to each cache entry and check for expiration when retrieving values.

Cache Invalidation

Implement a mechanism to invalidate cached values when the underlying data changes. This can be achieved by defining dependencies and updating the cache accordingly.

Cache Size Limit

To avoid memory overflow, you can set a limit on the number of items stored in the cache. When the limit is reached, you can remove the least recently used (LRU) entry to make room for new items.

Conclusion

Using promises, we can implement a caching mechanism to optimize the performance of our applications. By avoiding repetitive and expensive computations, we can improve efficiency and responsiveness. However, keep in mind that caching introduces its own set of challenges, such as cache invalidation and managing cache size. A well-designed caching mechanism can greatly benefit your application’s overall performance.

#References