In many applications, there are cases where certain computations or operations can be time-consuming and resource-intensive. One way to optimize such scenarios is by implementing a caching mechanism. Caching helps store the results of expensive computations so that subsequent requests can be served faster.

In this blog post, we will explore how to implement a caching mechanism specifically for expensive computations that are being handled asynchronously using promises.

Table of Contents

• Understanding the problem
• Designing the caching mechanism
• Implementing the caching mechanism
• Testing the caching mechanism
• Conclusion

Understanding the problem

Expensive computations can range from complex mathematical calculations to requesting data from external APIs. These computations can take a significant amount of time and resources which can negatively impact the performance of an application.

Without caching, each time a request is made for the same computation, the entire computation has to be executed from scratch. This can lead to decreased performance and increased response times.

Designing the caching mechanism

To implement a caching mechanism, we need to consider the following requirements:

1. The cache should be able to store the result of a computation along with its input parameters.
2. The cache should be able to retrieve the cached result when the same computation is requested again.
3. The cache should have a configurable expiration time to ensure that the cached results are refreshed periodically.
4. The cache should be able to handle multiple concurrent requests for the same computation efficiently.

Implementing the caching mechanism

We’ll start by creating a Cache class that will handle the caching functionality. This class will have methods to store and retrieve cached results based on the input parameters.

class Cache {
  constructor() {
    this.cache = new Map();
  }

  compute(key, computeFunction, expirationTime) {
    if (this.cache.has(key)) {
      const cachedResult = this.cache.get(key);
      // Check if the cached result has expired
      if (cachedResult.timestamp + expirationTime > Date.now()) {
        return Promise.resolve(cachedResult.result);
      }
    }

    // Compute the result using the provided computeFunction
    const resultPromise = computeFunction();
    resultPromise.then(result => {
      // Store the computed result in the cache
      this.cache.set(key, { result, timestamp: Date.now() });
    });

    return resultPromise;
  }
}

In the compute method of the Cache class, we check if the key already exists in the cache. If it does, we check if the cached result has expired based on the expiration time.

If the cached result is still valid, we return it immediately. Otherwise, we compute the result using the provided computeFunction and store the result in the cache for future use.

Testing the caching mechanism

Let’s see an example of how to use the caching mechanism:

// Create an instance of the Cache class
const cache = new Cache();

// Expensive computation function
function computeExpensiveResult() {
  return new Promise(resolve => {
    // Simulating an expensive computation with a delay
    setTimeout(() => {
      const result = Math.random();
      resolve(result);
    }, 3000); // Simulating a 3-second computation
  });
}

// Use the cache to compute and store the result
const computationPromise1 = cache.compute('computation1', computeExpensiveResult, 5000);
const computationPromise2 = cache.compute('computation1', computeExpensiveResult, 5000);

computationPromise1.then(result => {
  console.log('First computation result:', result);
});

computationPromise2.then(result => {
  console.log('Second computation result:', result);
});

In the above example, we create an instance of the Cache class and define the computeExpensiveResult function that simulates an expensive computation with a delay. We use the compute method of the cache to compute and store the result.

Since both computationPromise1 and computationPromise2 use the same key, the second computation uses the cached result from the first computation instead of recomputing it.

Conclusion

Implementing a caching mechanism for expensive computations can significantly improve the performance of an application by reducing the response time for subsequent requests. By leveraging promises and a well-designed caching mechanism, we can efficiently handle and cache the results of expensive computations, resulting in faster and more responsive applications.

By using caching, we can minimize the load on the system and provide a seamless user experience. Try implementing a similar caching mechanism in your own applications and see the performance improvements for yourself.

#references #caching