Advanced thread-safe generic wrapper for System.Runtime.Caching with comprehensive features including cache groups, dependency management, automatic population, and persistent disk storage.
Key Features:
• Cache groups for organized data management
• Dependency relationships between cache groups
• Automatic cache population with custom methods
• Persistent cache storage that survives application restarts
• Retrieve all items from a group with GetAllByGroup()
• Comprehensive metadata and monitoring with GetAllCacheMetadata()
• Detailed statistics and disk usage analysis
• Multiple expiration strategies (sliding/absolute)
• Auto-refresh with configurable intervals
• Thread-safe operations with minimal lock contention
• JSON-based serialization for persistent storage
Perfect for high-performance applications requiring sophisticated caching patterns, data persistence, and comprehensive monitoring capabilities.
A thread-safe, generic wrapper for System.Runtime.Caching that simplifies cache access and supports powerful caching patterns.
Overview
CacheUtility provides an easy-to-use abstraction over the standard .NET memory cache with additional features:
Automatic cache population
Various expiration strategies
Thread-safe operations
Support for cache groups
Dependency relationships between cache groups
Automatic background refresh functionality
Basic usage
Note: All examples assume you have added the using statement:
using CacheUtility;
Simple caching
The most common pattern is to request an item from the cache, providing a function to generate the item if it doesn't exist:
// Basic usage with default 30-minute sliding expiration
var result = Cache.Get("MyKey", "MyGroupName", () =>
{
return MyLongRunningTask();
});
Caching with expiration
// With custom sliding expiration
var result = Cache.Get("MyKey", "MyGroupName", TimeSpan.FromHours(1), () =>
{
return MyLongRunningTask();
});
// With absolute expiration
var result = Cache.Get("MyKey", "MyGroupName", DateTime.Now.AddDays(1), () =>
{
return MyLongRunningTask();
});
Basic examples
Caching user data
// Cache user data with a sliding expiration
var userData = Cache.Get($"User_{userId}", "UserProfiles", TimeSpan.FromMinutes(30), () =>
{
return database.GetUserById(userId);
});
Caching application settings
// Cache application settings with absolute expiration
var settings = Cache.Get("GlobalSettings", "AppConfig", DateTime.Now.AddHours(12), () =>
{
return configurationService.LoadSettings();
});
Async operations
For async operations, you can use the utility with async/await:
var result = await Cache.Get("MyKey", "MyGroupName", async () =>
{
return await MyLongRunningTaskAsync();
});
Cache management
Removing individual items
Remove a specific item from the cache:
Cache.Remove("MyKey", "MyGroupName");
Group operations
Remove an entire group of cached items:
Cache.RemoveGroup("MyGroupName");
Remove multiple groups:
Cache.RemoveGroup("GroupA", "GroupB", "GroupC");
Retrieving all items from a group
Get all cached items that belong to a specific group:
var allItems = Cache.GetAllByGroup("MyGroupName");
// Iterate through all items in the group
foreach (var kvp in allItems)
{
Console.WriteLine($"Key: {kvp.Key}, Value: {kvp.Value}");
}
// Access specific items if you know the key
if (allItems.ContainsKey("MySpecificKey"))
{
var specificItem = allItems["MySpecificKey"];
}
Cache metadata and monitoring
Get detailed metadata about cached items for monitoring, debugging, or displaying in management interfaces:
// Get metadata for all cached items
var allMetadata = Cache.GetAllCacheMetadata();
foreach (var metadata in allMetadata)
{
Console.WriteLine($"Key: {metadata.CacheKey}");
Console.WriteLine($" Group: {metadata.GroupName}");
Console.WriteLine($" Type: {metadata.DataType}");
Console.WriteLine($" Size: {metadata.EstimatedMemorySize:N0} bytes");
Console.WriteLine($" Last Refresh: {metadata.LastRefreshTime:yyyy-MM-dd HH:mm:ss}");
Console.WriteLine($" Refresh Interval: {metadata.RefreshInterval}");
Console.WriteLine($" Is Refreshing: {metadata.IsRefreshing}");
Console.WriteLine($" Populate Method: {metadata.PopulateMethodName ?? "Unknown"}");
if (metadata.CollectionCount.HasValue)
{
Console.WriteLine($" Items in Collection: {metadata.CollectionCount}");
}
}
// You can filter the results as needed
var userDataItems = allMetadata.Where(m => m.GroupName == "UserProfiles");
Available metadata properties
Each CacheItemMetadata object contains:
CacheKey: Original cache key (without group prefix)
GroupName: Cache group name
DataType: Type name of the cached object
EstimatedMemorySize: Estimated memory usage in bytes (using JSON serialization)
LastRefreshTime: When the data was last refreshed
LastRefreshAttempt: When the last refresh was attempted (regardless of success)
RefreshInterval: Auto-refresh interval
IsRefreshing: Whether a refresh operation is currently in progress
RefreshStartTime: When the current refresh operation started
CollectionCount: Number of items if the cached object is a collection
PopulateMethodName: Name of the method used to populate/refresh the cache item
RemovalCallbackName: Name of the removal callback method (currently not available due to MemoryCache limitations)
Populate method names
The PopulateMethodName property helps identify which methods are used to populate cache items:
Remove multiple items that contain specific strings:
Cache.Remove(new List<string> { "UserProfile", "123" }, "UserData");
// This will remove any cache key containing both "UserProfile" and "123"
Working with multiple cached items
// Cache some user data
Cache.Get("User1", "UserData", () => GetUserInfo(1));
Cache.Get("User2", "UserData", () => GetUserInfo(2));
Cache.Get("User3", "UserData", () => GetUserInfo(3));
// Get all cached items from the group
var allUsers = Cache.GetAllByGroup("UserData");
Console.WriteLine($"Found {allUsers.Count} cached users");
// Process each cached item
foreach (var user in allUsers)
{
Console.WriteLine($"User Key: {user.Key}, Data: {user.Value}");
}
Advanced features
Automatic data refresh
CacheUtility supports automatic background refresh of cached data at specified intervals. This feature ensures your cache stays up-to-date with fresh data while maintaining high performance by serving existing data immediately, even during refresh operations.
Key benefits:
Non-blocking: Cache calls return immediately with existing data, even when refresh is in progress
High availability: Your application remains responsive during slow data refresh operations
Automatic updates: Data stays fresh without manual intervention
// Cache data with automatic refresh every 5 minutes
var userData = Cache.Get("user_123", "UserProfiles",
TimeSpan.FromHours(1), // Sliding expiration
() => database.GetUserById(123), // Populate method
refresh: TimeSpan.FromMinutes(5) // Refresh interval
);
Non-blocking behavior example
// Even if GetExpensiveData() takes 10 seconds to execute,
// subsequent cache calls will return immediately with existing data
var expensiveData = Cache.Get("expensive_key", "DataGroup",
TimeSpan.FromMinutes(30),
() => GetExpensiveDataFromAPI(), // Slow operation
refresh: TimeSpan.FromMinutes(2)
);
// This call returns instantly, even if refresh is running in background
var sameData = Cache.Get("expensive_key", "DataGroup",
TimeSpan.FromMinutes(30),
() => GetExpensiveDataFromAPI(),
refresh: TimeSpan.FromMinutes(2)
);
Real-world refresh scenarios
API data caching:
var weatherData = Cache.Get($"weather_{cityId}", "WeatherCache",
TimeSpan.FromHours(2), // Cache for 2 hours max, after the cache item last has been accessed
() => weatherAPI.GetCurrentWeather(cityId),
refresh: TimeSpan.FromMinutes(15) // Refresh every 15 minutes
);
var config = Cache.Get("app_config", "Configuration",
TimeSpan.FromDays(1),
() => configService.LoadConfiguration(),
refresh: TimeSpan.FromMinutes(30) // Check for config updates every 30 minutes
);
Cache removal callbacks
CacheUtility supports optional removal callbacks that are invoked when cached items are removed from the cache. This is useful for cleanup operations, logging, or triggering dependent actions.
Basic removal callback
var result = Cache.Get("MyKey", "MyGroupName",
DateTime.Now.AddHours(1), // Either Absolute expiration
TimeSpan.FromMinutes(10), // Or Sliding expiration
CacheItemPriority.Default, // Priority
() => MyLongRunningTask(),
removedCallback: (args) => // Optional callback
{
Console.WriteLine($"Cache item removed. Key: {args.CacheItem.Key}, Reason: {args.RemovedReason}");
});
Removal reasons
The callback provides a CacheEntryRemovedArguments object that contains:
CacheItem: The cache item that was removed
RemovedReason: The reason for removal (Removed, Expired, Evicted, ChangeMonitorChanged)
Common removal reasons:
Removed: Item was explicitly removed
Expired: Item expired (absolute or sliding expiration)
Evicted: Item was evicted due to memory pressure
ChangeMonitorChanged: Item was removed due to a dependency change
Practical callback examples
Cleanup resources:
var fileData = Cache.Get("FileData", "Files",
TimeSpan.FromMinutes(30),
CacheItemPriority.Default,
() => LoadFileData("myfile.txt"),
removedCallback: (args) =>
{
if (args.CacheItem.Value is IDisposable disposable)
{
disposable.Dispose();
}
});
Trigger dependent operations:
var config = Cache.Get("AppConfig", "Configuration",
DateTime.Now.AddHours(12),
() => LoadConfiguration(),
removedCallback: (args) =>
{
// Refresh dependent services when configuration changes
if (args.RemovedReason == CacheEntryRemovedReason.Expired)
{
RefreshDependentServices();
}
});
Cache dependencies
Set up dependencies between cache groups so that when one group is cleared, its dependent groups are also cleared:
// Set up dependencies
Cache.SetDependencies("ParentGroup", "ChildGroup1", "ChildGroup2");
// Now when ParentGroup is removed, ChildGroup1 and ChildGroup2 will also be removed
Cache.RemoveGroup("ParentGroup");
Cascading cache invalidation
// Set up dependencies
Cache.SetDependencies("UserData", "UserProfiles", "UserPreferences", "UserActivity");
Cache.SetDependencies("UserProfiles", "ProfilePhotos");
// Now when UserData is cleared, all dependent caches are also cleared
Cache.RemoveGroup("UserData");
// This will clear UserData, UserProfiles, ProfilePhotos, UserPreferences, and UserActivity
Best practices
Group related items: Use meaningful group names to organize related cache items.
Consider expiration strategies: Choose between sliding expiration (reset on access) and absolute expiration (fixed time) based on your use case.
Set dependencies: Use cache dependencies to maintain consistency between related data.
Use short keys: Keep your cache keys concise but descriptive.
Choose appropriate refresh intervals:
Balance data freshness needs with system resources
Use longer intervals for stable data, shorter for rapidly changing data
Consider the cost of your populate method when setting refresh frequency
Remember that refresh happens in background, so cache remains available
Use removal callbacks wisely:
Use callbacks for cleanup operations (disposing resources, closing connections)
Consider performance impact - callbacks are executed synchronously
Avoid heavy operations in callbacks to prevent blocking cache operations
Use callbacks for logging and monitoring cache behavior
Performance considerations
The CacheUtility uses locks to ensure thread safety, but is designed to minimize lock contention.
Populate methods are only called once per cache miss, even under high concurrency.
Refresh operations are non-blocking: Cache calls return immediately with existing data, even during background refresh.
Background refresh uses Task.Run() to prevent blocking the main thread.
Multiple concurrent refresh requests for the same cache key are automatically deduplicated.
Consider memory usage when caching large objects or collections.
When to use cache groups vs. key prefixes
Cache groups: Use when you need to invalidate multiple related items at once.
Key prefixes: Use within your keys when you want to organize items but may need more granular control.
Memory management
The CacheUtility is built on top of .NET's MemoryCache, which has built-in memory pressure detection. However, be mindful of:
Setting appropriate cache priorities
Using reasonable expiration times
Caching only necessary data
Thread safety
All operations in CacheUtility are thread-safe. The implementation uses ReaderWriterLockSlim for efficient concurrent access and CacheLock for synchronizing modifications to the cache.