Let us see a more practical example to get a better understanding of the Singleton pattern. Assume that we are tasked with managing a system wide cache. A simple way to handle this would be as follows:
The above implementation might work if we are going to use a single instance of the CacheManager class throughout the entire application. But if we create multiple instances of the CacheManager class, we may encounter the following issues:
- Inconsistent cache data: Each instance would have its own separate cache, leading to inconsistent data across different parts of the application.
- Resource wastage: Multiple instances would consume additional memory and resources to maintain their individual caches, resulting in inefficient resource usage.
- Synchronization challenges: If multiple instances modify the cache concurrently, it can lead to synchronization issues and data inconsistencies.
In this scenario, by using a singleton class, we can ensure that there is a single, shared instance of the cache manager throughout the application.
In this example, we have a CacheManager class that includes the Singleton module. The class ensures that only one instance of the cache manager is created and shared across the application.
Using the singleton class, we can store and retrieve cached data from anywhere in the application like this:
Singleton objects are often used for managing global state or resources that should have only one instance. For example, you might use a singleton to handle database connections, configuration settings, or logging functionality.