Module Caching

By default, Nidus creates and destroys module instances on every request (DisposeRouteModule). Module caching pins selected modules so their instances survive across requests, avoiding repeated construction of expensive services.

Enabling caching

Memory cache for specific modules

GetNidus
  .UseCache(
    TModuleCacheManager.Create,
    [TUserModule, TOrderModule])   // pinned modules
  .Start(TAppModule.Create);

Source: TNidus.UseCache(ACache, AModules) calls ACache.SetPolicy(AModules).

Cache all modules

GetNidus
  .UseCache(TModuleCacheManager.Create)
  .Start(TAppModule.Create);

// Then enable globally:
GetNidus.Cache.EnableAll;

Or use the sentinel class in SetPolicy:

GetNidus.Cache.SetPolicy([TNidusCacheAll]);

TNidusCacheAll is a marker class defined in Nidus.Module.Cache.Interfaces; passing it sets FCacheAll := True.

Cache API (IModuleCache)

var LCache := GetNidus.Cache;  // returns IModuleCache

// Pin additional modules at runtime
LCache.SetPolicy([TReportModule]);

// Enable caching for all modules
LCache.EnableAll;

// Disable caching and evict all cached instances
LCache.DisableAll;

// Evict a single module's cached instance
LCache.Invalidate(TUserModule);

// Check whether a module is cached
if LCache.IsEnabledFor(TUserModule) then ...;

// Evict all cached instances (without changing policy)
LCache.Clear;

How DisposeRouteModule respects the cache

TModuleProvider.DisposeModule checks IModuleCache.IsEnabledFor(LRoute.Module) before calling FreeAndNil(LRoute.ModuleInstance). If the module is cached, the instance is kept alive and reused on the next matching request.

TModuleCacheManager internals

Field	Type	Role
FInstances	TObjectDictionary<string, TObject>	Live cached instances, owns values
FEnabled	TDictionary<string, Byte>	Set of enabled module keys
FCacheAll	Boolean	Fast-path "cache everything" flag
FLock	TCriticalSection	Thread-safety for all operations

ResolveInstance(AModuleClass, AFactory) is the core method: if the class is cached and an instance exists, it returns the existing one; otherwise it calls AFactory() and stores the result.

Source: Nidus.Module.Cache — TModuleCacheManager.