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GroupDocs.Viewer.UI.Api.InMemory.Cache 26.4.0

GroupDocs.Viewer.UI.Api.InMemory.Cache

GroupDocs.Viewer.UI.Api.InMemory.Cache is an in-memory caching implementation that can be used with GroupDocs.Viewer.UI.Api. It provides fast, in-memory caching for document rendering results in your GroupDocs.Viewer.UI application.

Installation

To use InMemory Cache in your ASP.NET Core project:

1. Add the required package to your project:

dotnet add package GroupDocs.Viewer.UI.Api.InMemory.Cache

2. Configure InMemory Cache in your Startup class:

var builder = WebApplication.CreateBuilder(args);

builder.Services
 .AddGroupDocsViewerUI();

builder.Services
 .AddControllers()
 .AddGroupDocsViewerSelfHostApi()
 .AddLocalStorage("./Files")
 .AddInMemoryCache(config =>
 {
 config.SetCacheEntryExpirationTimeoutMinutes(60); // Cache entries expire after 60 minutes
 config.SetGroupCacheEntriesByFile(true); // Group cache entries by file
 });

var app = builder.Build();

app
 .UseRouting()
 .UseEndpoints(endpoints =>
 {
 endpoints.MapGroupDocsViewerUI(options =>
 {
 options.UIPath = "/viewer";
 options.ApiEndpoint = "/viewer-api";
 });
 endpoints.MapGroupDocsViewerApi(options =>
 {
 options.ApiPath = "/viewer-api";
 });
 });

await app.RunAsync();

Configuration Options

The InMemory Cache implementation supports the following configuration options:

• CacheEntryExpirationTimeoutMinutes (Optional): The expiration timeout of each cache entry in minutes. Default is 0, which means cache entries never expire.
• GroupCacheEntriesByFile (Optional): When enabled, eviction of any cache entry leads to eviction of all cache entries for that file. This setting only takes effect when CacheEntryExpirationTimeoutMinutes is greater than zero.

You can also configure these settings through appsettings.json:

{
 "GroupDocsViewerUIApiInMemoryCache": {
 "CacheEntryExpirationTimeoutMinutes": 60,
 "GroupCacheEntriesByFile": true
 }
}

Technical Implementation

The InMemory Cache implementation uses ASP.NET Core's built-in IMemoryCache for storing cached data. Here's how it works:

Cache Key Structure

• Each cache entry is identified by a composite key: {filePath}_{cacheKey}
• The filePath represents the document being cached
• The cacheKey represents the specific cached item (e.g., page thumbnail, page content)

Cache Entry Management

• Cache entries are stored in the application's process memory
• Uses MemoryCacheEntryOptions for controlling entry behavior
• Supports both synchronous and asynchronous operations through IFileCache interface

Expiration Mechanism

When CacheEntryExpirationTimeoutMinutes is set:

1. A CancellationTokenSource is created for each cache entry
2. The token source is configured to cancel after the specified timeout
3. Cache entries are linked to their token source through CancellationChangeToken
4. When the token is cancelled, the cache entry is automatically evicted

File-based Grouping

When GroupCacheEntriesByFile is enabled:

1. A single CancellationTokenSource is shared among all cache entries for a file
2. The token source key is {filePath}__CTS
3. When any cache entry expires, all entries for that file are evicted together
4. This ensures consistency when a file's cache entries need to be invalidated

Memory Management

• Uses ASP.NET Core's built-in memory management
• Automatically handles memory pressure through the framework's eviction policies
• No explicit memory limits are set, relying on the system's available memory
• Cache entries are not persisted between application restarts

Performance Considerations

When using InMemory Cache:

1. Cache size is limited by available system memory
2. Cache is cleared when the application restarts
3. Best suited for:
   • Small to medium-sized document sets
   • Applications with moderate concurrent users
   • Development and testing environments
4. Not recommended for:
   • Large document sets
   • High-traffic production environments
   • Distributed applications

License

This project is licensed under the MIT License - see the file for details.