Go: how to create an in-memory cache for a REST API

In-memory caches are a crucial component for improving the performance of a REST API. In Go, you can easily implement an in-memory cache to temporarily store data frequently requested by clients, thus reducing the load on your server and improving the overall responsiveness of the API. In this article, we will explore how to implement an in-memory cache for a REST API using the Go programming language.

To get started, import the Go libraries needed to create an in-memory cache. The sync package will help us securely manage concurrent cache access:

import (
     "sync"
)

Create a structure representing the in-memory cache. This structure should include a map to store the data and a mutex to ensure secure concurrent access:

type MemoryCache struct {
     cache map[string]interface{}
     mutex sync.RWMutex
}

In your main code, initialize a new instance of MemoryCache:

func main() {
     cache := MemoryCache{
         cache: make(map[string]interface{}),
     }
     // ...
}

When you receive an API request, first check whether the requested data is already in the cache. If yes, return them directly. If not, perform computation or data retrieval and add it to the cache for future requests:

func (c *MemoryCache) Get(key string) (interface{}, bool) {
     c.mutex.RLock()
     defer c.mutex.RUnlock()

     data, exists := c.cache[key]
     return data, exists
}

func (c *MemoryCache) Set(key string, data interface{}) {
     c.mutex.Lock()
     defer c.mutex.Unlock()

     c.cache[key] = data
}

In your API routes, first check whether the requested data is present in the cache. If they are, return the data from the cache. Otherwise, run the request handling logic as usual and add the results to the cache for future requests:

func yourAPIRouteHandler(w http.ResponseWriter, r *http.Request) {
     key := r.URL.String()

     // Search cache
     if data, exists := cache.Get(key); exists {
         // Data found in cache, return it
         respondWithJSON(w, http.StatusOK, data)
         return
     }

     // Data not found in cache, execute request handling logic
     result := fetchFromDatabaseOrComputeData()

     // Add the results to the cache for future requests
     cache.Set(key, result)

     respondWithJSON(w, http.StatusOK, result)
}

Conclusions

Implementing an in-memory cache for a REST API in Go is an effective way to improve performance and reduce load on your server. By using mutex synchronization, you can ensure safe concurrent access to the cache. Make sure you handle the logic of adding and retrieving data from the cache appropriately in your API routes.