I am following the blog http://www.venkatbaggu.com/signalr-database-update-notifications-asp-net-mvc-usiing-sql-dependency/ to get a signalR push message out to connected clients.
My debugger never hits the onchange event.
my Global.asax.cs:
string connString = ConfigurationManager.ConnectionStrings["DefaultConnection"].ConnectionString;
protected void Application_Start()
{
// basic stuff
SqlDependency.Start(connString);
var repo = new Repositories.MarkerRepository();
repo.GetAllMarkers(); // to register the dependency
}
My MarkerRepository.cs:
readonly string _connString = ConfigurationManager.ConnectionStrings["DefaultConnection"].ConnectionString;
private MarkersHub _mh = new MarkersHub(); // my signalr hub class
public IEnumerable<House> GetAllMarkers()
{
var markers = new List<House>();
using (var connection = new SqlConnection(_connString))
{
connection.Open();
using (var command = new SqlCommand(#"SELECT * FROM [dbo].Houses", connection))
{
command.Notification = null;
var dependency = new SqlDependency(command);
dependency.OnChange += new OnChangeEventHandler(dependency_OnChange);
if (connection.State == ConnectionState.Closed)
connection.Open();
var reader = command.ExecuteReader();
while (reader.Read())
{
markers.Add(item: new House {
ID = (int)reader["ID"],
Name = (string)reader["Name"],
Code = reader["Code"] != DBNull.Value ? (string)reader["Code"] : "",
Latitude = Convert.ToDouble(reader["Latitude"]),
Longitude = Convert.ToDouble(reader["Longitude"])
});
}
}
}
return markers;
}
private void dependency_OnChange(object sender, SqlNotificationEventArgs e)
{
if (e.Type == SqlNotificationType.Change)
{
_mh.SendMarkers();
}
}
I have had a hit once but it was no change, only a notification for subscribe. I have read a lot about resubscribe, but when it hit this event the sql:
select * from sys.dm_qn_subscriptions
still returns no rows. Not on my db or master. So I think that there is an error in the blog post with the re-subscribe to the on change event? This sample https://msdn.microsoft.com/en-us/library/a52dhwx7(VS.80).aspx does unregister in the onchange event and calls the method which registers a new event. Can someone verify my assumption?
These were the values for the SqlNotificationEventArgs e in my event and told me that my query to depend on, was invalid.
SqlNotificationEventArgs.Type --> SqlNotificationType.Subscribe
SqlNotificationEventArgs.Info --> SqlNotificationInfo.Invalid
SqlNotificationEventArgs.Source --> SqlNotificationSource.Statement
The statement may not use the asterisk () or table_name. syntax to specify columns.
source https://msdn.microsoft.com/en-us/library/ms181122.aspx
How to use DecorateAllWith to decorate with a DynamicProxy all instances implements an interface?
For example:
public class ApplicationServiceInterceptor : IInterceptor
{
public void Intercept(IInvocation invocation)
{
// ...
invocation.Proceed();
// ...
}
}
public class ApplicationServiceConvention : IRegistrationConvention
{
public void Process(Type type, Registry registry)
{
if (type.CanBeCastTo<IApplicationService>() && type.IsInterface)
{
var proxyGenerator = new ProxyGenerator();
// ??? how to use proxyGenerator??
// ???
registry.For(type).DecorateAllWith(???); // How to use DecorateAllWith DynamicProxy ...??
}
}
}
I could decorate some interfaces to concrete types using (for example):
var proxyGenerator = new ProxyGenerator();
registry.For<IApplicationService>().Use<BaseAppService>().DecorateWith(service => proxyGenerator.CreateInterfaceProxyWithTargetInterface(....))
But havent able to using DecorateAll to do this.
To call registry.For<>().Use<>().DecorateWith() I have to do this:
if (type.CanBeCastTo<IApplicationService>() && !type.IsAbstract)
{
var interfaceToProxy = type.GetInterface("I" + type.Name);
if (interfaceToProxy == null)
return null;
var proxyGenerator = new ProxyGenerator();
// Build expression to use registration by reflection
var expression = BuildExpressionTreeToCreateProxy(proxyGenerator, type, interfaceType, new MyInterceptor());
// Register using reflection
var f = CallGenericMethod(registry, "For", interfaceToProxy);
var u = CallGenericMethod(f, "Use", type);
CallMethod(u, "DecorateWith", expression);
}
Only for crazy minds ...
I start to get very tired of StructureMap, many changes and no documentation, I have been read the source code but ... too many efforts for my objective ...
If someone can give me a bit of light I will be grateful.
Thanks in advance.
In addition ... I post here the real code of my helper to generate the expression tree an register the plugin family:
public static class RegistrationHelper
{
public static void RegisterWithInterceptors(this Registry registry, Type interfaceToProxy, Type concreteType,
IInterceptor[] interceptors, ILifecycle lifecycle = null)
{
var proxyGenerator = new ProxyGenerator();
// Generate expression tree to call DecoreWith of StructureMap SmartInstance type
// registry.For<interfaceToProxy>().Use<concreteType>()
// .DecoreWith(ex => (IApplicationService)
// proxyGenerator.CreateInterfaceProxyWithTargetInterface(interfaceToProxy, ex, interceptors)
var expressionParameter = Expression.Parameter(interfaceToProxy, "ex");
var proxyGeneratorConstant = Expression.Constant(proxyGenerator);
var interfaceConstant = Expression.Constant(interfaceToProxy);
var interceptorConstant = Expression.Constant(interceptors);
var methodCallExpression = Expression.Call(proxyGeneratorConstant,
typeof (ProxyGenerator).GetMethods().First(
met => met.Name == "CreateInterfaceProxyWithTargetInterface"
&& !met.IsGenericMethod && met.GetParameters().Count() == 3),
interfaceConstant,
expressionParameter,
interceptorConstant);
var convert = Expression.Convert(methodCallExpression, interfaceToProxy);
var func = typeof(Func<,>).MakeGenericType(interfaceToProxy, interfaceToProxy);
var expr = Expression.Lambda(func, convert, expressionParameter);
// Register using reflection
registry.CallGenericMethod("For", interfaceToProxy, new[] {(object) lifecycle /*Lifecicle*/})
.CallGenericMethod("Use", concreteType)
.CallNoGenericMethod("DecorateWith", expr);
}
}
public static class CallMethodExtensions
{
/// <summary>
/// Call a method with Generic parameter by reflection (obj.methodName[genericType](parameters)
/// </summary>
/// <returns></returns>
public static object CallGenericMethod(this object obj, string methodName, Type genericType, params object[] parameters)
{
var metod = obj.GetType().GetMethods().First(m => m.Name == methodName && m.IsGenericMethod);
var genericMethod = metod.MakeGenericMethod(genericType);
return genericMethod.Invoke(obj, parameters);
}
/// <summary>
/// Call a method without Generic parameter by reflection (obj.methodName(parameters)
/// </summary>
/// <returns></returns>
public static object CallNoGenericMethod(this object obj, string methodName, params object[] parameters)
{
var method = obj.GetType().GetMethods().First(m => m.Name == methodName && !m.IsGenericMethod);
return method.Invoke(obj, parameters);
}
}
Almost two years later I have needed return this issue for a new project. This time I have solved it this time I have used StructureMap 4.
You can use a custom interceptor policy to decorate an instance in function of his type. You have to implement one interceptor, one interceptor policy and configure it on a registry.
The Interceptor
public class MyExInterceptor : Castle.DynamicProxy.IInterceptor
{
public void Intercept(Castle.DynamicProxy.IInvocation invocation)
{
Console.WriteLine("-- Call to " + invocation.Method);
invocation.Proceed();
}
}
The interceptor policy
public class CustomInterception : IInterceptorPolicy
{
public string Description
{
get { return "good interception policy"; }
}
public IEnumerable<IInterceptor> DetermineInterceptors(Type pluginType, Instance instance)
{
if (pluginType == typeof(IAppService))
{
// DecoratorInterceptor is the simple case of wrapping one type with another
// concrete type that takes the first as a dependency
yield return new FuncInterceptor<IAppService>(i =>
(IAppService)
DynamicProxyHelper.CreateInterfaceProxyWithTargetInterface(typeof(IAppService), i));
}
}
}
Configuration
var container = new Container(_ =>
{
_.Policies.Interceptors(new CustomInterception());
_.For<IAppService>().Use<AppServiceImplementation>();
});
var service = container.GetInstance<IAppService>();
service.DoWork();
You can get a working example on this gist https://gist.github.com/tolemac/3e31b44b7fc7d0b49c6547018f332d68, in the gist you can find three types of decoration, the third is like this answer.
Using it you can configure the decorators of your services easily.
It has been decided by the ASP.NET Web API team to use the JSON.NET library for model binding JSON data. However, "normal" MVC controllers still use the inferior JsonDataContractSerializer. This causes issues with parsing dates, and is causing me much headache.
See this for reference:
http://www.devcurry.com/2013/04/json-dates-are-different-in-aspnet-mvc.html
The author chooses to solve the issue in the Knockout layer on the client. But I would prefer to solve this by using the same JSON.NET model binder in MVC controllers as in Web API controllers.
How do I substitute a different JSON model binder into ASP.NET MVC? Specifically, the JSON.NET library. Using the same model binder from Web API would be ideal if possible.
I have done this, and also heavily customized the serialization that Json.NET is doing, by:
Replace the default formatter in global.asax.cs, Application_Start:
GlobalConfiguration.Configuration.Formatters.Remove(GlobalConfiguration.Configuration.Formatters.JsonFormatter);
GlobalConfiguration.Configuration.Formatters.Add(new CustomJsonMediaTypeFormatter());
And my CustomJsonMediaTypeFormatter is:
public static class CustomJsonSettings
{
private static JsonSerializerSettings _settings;
public static JsonSerializerSettings Instance
{
get
{
if (_settings == null)
{
var settings = new JsonSerializerSettings();
// Must convert times coming from the client (always in UTC) to local - need both these parts:
settings.Converters.Add(new IsoDateTimeConverter { DateTimeStyles = System.Globalization.DateTimeStyles.AssumeUniversal }); // Critical part 1
settings.DateTimeZoneHandling = DateTimeZoneHandling.Local; // Critical part 2
// Skip circular references
settings.ReferenceLoopHandling = ReferenceLoopHandling.Ignore;
// Handle special cases in json (self-referencing loops, etc)
settings.ContractResolver = new CustomJsonResolver();
_settings = settings;
}
return _settings;
}
}
}
public class CustomJsonMediaTypeFormatter : MediaTypeFormatter
{
public JsonSerializerSettings _jsonSerializerSettings;
public CustomJsonMediaTypeFormatter()
{
_jsonSerializerSettings = CustomJsonSettings.Instance;
// Fill out the mediatype and encoding we support
SupportedMediaTypes.Add(new MediaTypeHeaderValue("application/json"));
SupportedEncodings.Add(new UTF8Encoding(false, true));
}
public override bool CanReadType(Type type)
{
return true;
}
public override bool CanWriteType(Type type)
{
return true;
}
public override Task<object> ReadFromStreamAsync(Type type, Stream stream, HttpContent content, IFormatterLogger formatterLogger)
{
// Create a serializer
JsonSerializer serializer = JsonSerializer.Create(_jsonSerializerSettings);
// Create task reading the content
return Task.Factory.StartNew(() =>
{
using (StreamReader streamReader = new StreamReader(stream, SupportedEncodings.First()))
{
using (JsonTextReader jsonTextReader = new JsonTextReader(streamReader))
{
return serializer.Deserialize(jsonTextReader, type);
}
}
});
}
public override Task WriteToStreamAsync(Type type, object value, Stream stream, HttpContent content, TransportContext transportContext)
{
// Create a serializer
JsonSerializer serializer = JsonSerializer.Create(_jsonSerializerSettings);
// Create task writing the serialized content
return Task.Factory.StartNew(() =>
{
using (StreamWriter streamWriter = new StreamWriter(stream, SupportedEncodings.First()))
{
using (JsonTextWriter jsonTextWriter = new JsonTextWriter(streamWriter))
{
serializer.Serialize(jsonTextWriter, value);
}
}
});
}
}
And finally, the CustomJsonResolver:
public class CustomJsonResolver : DefaultContractResolver
{
protected override IList<JsonProperty> CreateProperties(Type type, Newtonsoft.Json.MemberSerialization memberSerialization)
{
var list = base.CreateProperties(type, memberSerialization);
// Custom stuff for my app
if (type == typeof(Foo))
{
RemoveProperty(list, "Bar");
RemoveProperty(list, "Bar2");
}
return list;
}
private void RemoveProperty(IList<JsonProperty> list, string propertyName)
{
var rmc = list.FirstOrDefault(x => x.PropertyName == propertyName);
if (rmc != null)
{
list.Remove(rmc);
}
}
}
The JsonNetValueProviderFactory proposed here works better than the others I've tried (I had issues with arrays using Greg Ennis' one for example). This link also propose a solution to return Json from an action.
I have almost exactly the same scenario described by Nathon Taylor in ASP.NET MVC - Sharing Session State Between Controllers. The problem is that if I save the path to the images inside a Session variable List<string> it is not being defined back in the ItemController so all the paths are being lost... Here's my setup:
Inside ImageController I have the Upload() action method:
public ActionResult Upload()
{
var newFile = System.Web.HttpContext.Current.Request.Files["Filedata"];
string guid = Guid.NewGuid() + newFile.FileName;
string itemImagesFolder = Server.MapPath(Url.Content("~/Content/ItemImages/"));
string fileName = itemImagesFolder + "originals/" + guid;
newFile.SaveAs(fileName);
var resizePath = itemImagesFolder + "temp/";
string finalPath;
foreach (var dim in _dimensions)
{
var resizedPath = _imageService.ResizeImage(fileName, resizePath, dim.Width + (dim.Width * 10/100), guid);
var bytes = _imageService.CropImage(resizedPath, dim.Width, dim.Height, 0, 0);
finalPath = itemImagesFolder + dim.Title + "/" + guid;
_imageService.SaveImage(bytes, finalPath);
}
AddToSession(guid);
var returnPath = Url.Content("~/Content/ItemImages/150x150/" + guid);
return Content(returnPath);
}
private void AddToSession(string fileName)
{
if(Session[SessionKeys.Images] == null)
{
var imageList = new List<string>();
Session[SessionKeys.Images] = imageList;
}
((List<string>)Session[SessionKeys.Images]).Add(fileName);
}
Then inside my ItemController I have the New() action method which has the following code:
List<string> imageNames;
var images = new List<Image>();
if (Session[SessionKeys.Images] != null) //always returns false
{
imageNames = Session[SessionKeys.Images] as List<string>;
int rank = 1;
foreach (var name in imageNames)
{
var img = new Image {Name = name, Rank = rank};
images.Add(img);
rank++;
}
}
Ok so why is this happening and how do I solve it?
Also, I was thinking of whether I could move the ActionMethod that takes care of the upload of the images into the ItemController and store the image paths inside a List property on the ItemController itself, would that actually work? Note though, that images are being uploaded and taken care of via an AJAX request. Then when the user submits the item entry form, all the data about the Item along with the images should be saved to the database...
Update:
I've updated the code. Also I think I should add that I'm using StructureMap as my controller factorory. Could it be a scoping issue? What is the default scope that is usually used by StructureMap?
public class StructureMapDependencyResolver : IDependencyResolver
{
public StructureMapDependencyResolver(IContainer container)
{
_container = container;
}
public object GetService(Type serviceType)
{
if (serviceType.IsAbstract || serviceType.IsInterface)
{
return _container.TryGetInstance(serviceType);
}
else
{
return _container.GetInstance(serviceType);
}
}
public IEnumerable<object> GetServices(Type serviceType)
{
return _container.GetAllInstances<object>()
.Where(s => s.GetType() == serviceType);
}
private readonly IContainer _container;
}
And inside my Global.asax file:
private static IContainer ConfigureStructureMap()
{
ObjectFactory.Configure(x =>
{
x.For<IDatabaseFactory>().Use<EfDatabaseFactory>();
x.For<IUnitOfWork>().Use<UnitOfWork>();
x.For<IGenericMethodsRepository>().Use<GenericMethodsRepository>();
x.For<IUserService>().Use<UsersManager>();
x.For<IBiddingService>().Use<BiddingService>();
x.For<ISearchService>().Use<SearchService>();
x.For<IFaqService>().Use<FaqService>();
x.For<IItemsService>().Use<ItemsService>();
x.For<IMessagingService>().Use<MessagingService>();
x.For<IStaticQueriesService>().Use<StaticQueriesService>();
x.For < IImagesService<Image>>().Use<ImagesService>();
x.For<ICommentingService>().Use<CommentingService>();
x.For<ICategoryService>().Use<CategoryService>();
x.For<IHelper>().Use<Helper>();
x.For<HttpContext>().HttpContextScoped().Use(HttpContext.Current);
x.For(typeof(Validator<>)).Use(typeof(NullValidator<>));
x.For<Validator<Rating>>().Use<RatingValidator>();
x.For<Validator<TopLevelCategory>>().Use<TopLevelCategoryValidator>();
});
Func<Type, IValidator> validatorFactory = type =>
{
var valType = typeof(Validator<>).MakeGenericType(type);
return (IValidator)ObjectFactory.GetInstance(valType);
};
ObjectFactory.Configure(x => x.For<IValidationProvider>().Use(() => new ValidationProvider(validatorFactory)));
return ObjectFactory.Container;
}
Any thoughts?
I just added this to Global.asax.cs
protected void Session_Start()
{
}
It seems that this fixed the issue. I set a breakpoint that gets hit only once per session (as expected).
One possible reason for this is that the application domain restarts between the first and the second actions and because session is stored in memory it will be lost. This could happen if you recompile the application between the two. Try putting a breakpoints in the Application_Start and Session_Start callbacks in Global.asax and see if they are called twice.
Are you ever using it other than accessing HttpContext.Current directly in your code? In other words, are there any places where you're injecting the HttpContext for the sake of mocking in unit tests?
If you're only accessing it directly in your methods, then there's no reason to have the entry x.For<HttpContext>().HttpContextScoped().Use(HttpContext.Current); in you application startup. I wonder if it would start working if you removed it.
I have read lots of information about page caching and partial page caching in a MVC application. However, I would like to know how you would cache data.
In my scenario I will be using LINQ to Entities (entity framework). On the first call to GetNames (or whatever the method is) I want to grab the data from the database. I want to save the results in cache and on the second call to use the cached version if it exists.
Can anyone show an example of how this would work, where this should be implemented (model?) and if it would work.
I have seen this done in traditional ASP.NET apps , typically for very static data.
Here's a nice and simple cache helper class/service I use:
using System.Runtime.Caching;
public class InMemoryCache: ICacheService
{
public T GetOrSet<T>(string cacheKey, Func<T> getItemCallback) where T : class
{
T item = MemoryCache.Default.Get(cacheKey) as T;
if (item == null)
{
item = getItemCallback();
MemoryCache.Default.Add(cacheKey, item, DateTime.Now.AddMinutes(10));
}
return item;
}
}
interface ICacheService
{
T GetOrSet<T>(string cacheKey, Func<T> getItemCallback) where T : class;
}
Usage:
cacheProvider.GetOrSet("cache key", (delegate method if cache is empty));
Cache provider will check if there's anything by the name of "cache id" in the cache, and if there's not, it will call a delegate method to fetch data and store it in cache.
Example:
var products=cacheService.GetOrSet("catalog.products", ()=>productRepository.GetAll())
Reference the System.Web dll in your model and use System.Web.Caching.Cache
public string[] GetNames()
{
string[] names = Cache["names"] as string[];
if(names == null) //not in cache
{
names = DB.GetNames();
Cache["names"] = names;
}
return names;
}
A bit simplified but I guess that would work. This is not MVC specific and I have always used this method for caching data.
I'm referring to TT's post and suggest the following approach:
Reference the System.Web dll in your model and use System.Web.Caching.Cache
public string[] GetNames()
{
var noms = Cache["names"];
if(noms == null)
{
noms = DB.GetNames();
Cache["names"] = noms;
}
return ((string[])noms);
}
You should not return a value re-read from the cache, since you'll never know if at that specific moment it is still in the cache. Even if you inserted it in the statement before, it might already be gone or has never been added to the cache - you just don't know.
So you add the data read from the database and return it directly, not re-reading from the cache.
For .NET 4.5+ framework
add reference: System.Runtime.Caching
add using statement:
using System.Runtime.Caching;
public string[] GetNames()
{
var noms = System.Runtime.Caching.MemoryCache.Default["names"];
if(noms == null)
{
noms = DB.GetNames();
System.Runtime.Caching.MemoryCache.Default["names"] = noms;
}
return ((string[])noms);
}
In the .NET Framework 3.5 and earlier versions, ASP.NET provided an in-memory cache implementation in the System.Web.Caching namespace. In previous versions of the .NET Framework, caching was available only in the System.Web namespace and therefore required a dependency on ASP.NET classes. In the .NET Framework 4, the System.Runtime.Caching namespace contains APIs that are designed for both Web and non-Web applications.
More info:
https://msdn.microsoft.com/en-us/library/dd997357(v=vs.110).aspx
https://learn.microsoft.com/en-us/dotnet/framework/performance/caching-in-net-framework-applications
Steve Smith did two great blog posts which demonstrate how to use his CachedRepository pattern in ASP.NET MVC. It uses the repository pattern effectively and allows you to get caching without having to change your existing code.
http://ardalis.com/Introducing-the-CachedRepository-Pattern
http://ardalis.com/building-a-cachedrepository-via-strategy-pattern
In these two posts he shows you how to set up this pattern and also explains why it is useful. By using this pattern you get caching without your existing code seeing any of the caching logic. Essentially you use the cached repository as if it were any other repository.
I have used it in this way and it works for me.
https://msdn.microsoft.com/en-us/library/system.web.caching.cache.add(v=vs.110).aspx
parameters info for system.web.caching.cache.add.
public string GetInfo()
{
string name = string.Empty;
if(System.Web.HttpContext.Current.Cache["KeyName"] == null)
{
name = GetNameMethod();
System.Web.HttpContext.Current.Cache.Add("KeyName", name, null, DateTime.Noew.AddMinutes(5), Cache.NoSlidingExpiration, CacheitemPriority.AboveNormal, null);
}
else
{
name = System.Web.HttpContext.Current.Cache["KeyName"] as string;
}
return name;
}
AppFabric Caching is distributed and an in-memory caching technic that stores data in key-value pairs using physical memory across multiple servers. AppFabric provides performance and scalability improvements for .NET Framework applications. Concepts and Architecture
Extending #Hrvoje Hudo's answer...
Code:
using System;
using System.Runtime.Caching;
public class InMemoryCache : ICacheService
{
public TValue Get<TValue>(string cacheKey, int durationInMinutes, Func<TValue> getItemCallback) where TValue : class
{
TValue item = MemoryCache.Default.Get(cacheKey) as TValue;
if (item == null)
{
item = getItemCallback();
MemoryCache.Default.Add(cacheKey, item, DateTime.Now.AddMinutes(durationInMinutes));
}
return item;
}
public TValue Get<TValue, TId>(string cacheKeyFormat, TId id, int durationInMinutes, Func<TId, TValue> getItemCallback) where TValue : class
{
string cacheKey = string.Format(cacheKeyFormat, id);
TValue item = MemoryCache.Default.Get(cacheKey) as TValue;
if (item == null)
{
item = getItemCallback(id);
MemoryCache.Default.Add(cacheKey, item, DateTime.Now.AddMinutes(durationInMinutes));
}
return item;
}
}
interface ICacheService
{
TValue Get<TValue>(string cacheKey, Func<TValue> getItemCallback) where TValue : class;
TValue Get<TValue, TId>(string cacheKeyFormat, TId id, Func<TId, TValue> getItemCallback) where TValue : class;
}
Examples
Single item caching (when each item is cached based on its ID because caching the entire catalog for the item type would be too intensive).
Product product = cache.Get("product_{0}", productId, 10, productData.getProductById);
Caching all of something
IEnumerable<Categories> categories = cache.Get("categories", 20, categoryData.getCategories);
Why TId
The second helper is especially nice because most data keys are not composite. Additional methods could be added if you use composite keys often. In this way you avoid doing all sorts of string concatenation or string.Formats to get the key to pass to the cache helper. It also makes passing the data access method easier because you don't have to pass the ID into the wrapper method... the whole thing becomes very terse and consistant for the majority of use cases.
Here's an improvement to Hrvoje Hudo's answer. This implementation has a couple of key improvements:
Cache keys are created automatically based on the function to update data and the object passed in that specifies dependencies
Pass in time span for any cache duration
Uses a lock for thread safety
Note that this has a dependency on Newtonsoft.Json to serialize the dependsOn object, but that can be easily swapped out for any other serialization method.
ICache.cs
public interface ICache
{
T GetOrSet<T>(Func<T> getItemCallback, object dependsOn, TimeSpan duration) where T : class;
}
InMemoryCache.cs
using System;
using System.Reflection;
using System.Runtime.Caching;
using Newtonsoft.Json;
public class InMemoryCache : ICache
{
private static readonly object CacheLockObject = new object();
public T GetOrSet<T>(Func<T> getItemCallback, object dependsOn, TimeSpan duration) where T : class
{
string cacheKey = GetCacheKey(getItemCallback, dependsOn);
T item = MemoryCache.Default.Get(cacheKey) as T;
if (item == null)
{
lock (CacheLockObject)
{
item = getItemCallback();
MemoryCache.Default.Add(cacheKey, item, DateTime.Now.Add(duration));
}
}
return item;
}
private string GetCacheKey<T>(Func<T> itemCallback, object dependsOn) where T: class
{
var serializedDependants = JsonConvert.SerializeObject(dependsOn);
var methodType = itemCallback.GetType();
return methodType.FullName + serializedDependants;
}
}
Usage:
var order = _cache.GetOrSet(
() => _session.Set<Order>().SingleOrDefault(o => o.Id == orderId)
, new { id = orderId }
, new TimeSpan(0, 10, 0)
);
public sealed class CacheManager
{
private static volatile CacheManager instance;
private static object syncRoot = new Object();
private ObjectCache cache = null;
private CacheItemPolicy defaultCacheItemPolicy = null;
private CacheEntryRemovedCallback callback = null;
private bool allowCache = true;
private CacheManager()
{
cache = MemoryCache.Default;
callback = new CacheEntryRemovedCallback(this.CachedItemRemovedCallback);
defaultCacheItemPolicy = new CacheItemPolicy();
defaultCacheItemPolicy.AbsoluteExpiration = DateTime.Now.AddHours(1.0);
defaultCacheItemPolicy.RemovedCallback = callback;
allowCache = StringUtils.Str2Bool(ConfigurationManager.AppSettings["AllowCache"]); ;
}
public static CacheManager Instance
{
get
{
if (instance == null)
{
lock (syncRoot)
{
if (instance == null)
{
instance = new CacheManager();
}
}
}
return instance;
}
}
public IEnumerable GetCache(String Key)
{
if (Key == null || !allowCache)
{
return null;
}
try
{
String Key_ = Key;
if (cache.Contains(Key_))
{
return (IEnumerable)cache.Get(Key_);
}
else
{
return null;
}
}
catch (Exception)
{
return null;
}
}
public void ClearCache(string key)
{
AddCache(key, null);
}
public bool AddCache(String Key, IEnumerable data, CacheItemPolicy cacheItemPolicy = null)
{
if (!allowCache) return true;
try
{
if (Key == null)
{
return false;
}
if (cacheItemPolicy == null)
{
cacheItemPolicy = defaultCacheItemPolicy;
}
String Key_ = Key;
lock (Key_)
{
return cache.Add(Key_, data, cacheItemPolicy);
}
}
catch (Exception)
{
return false;
}
}
private void CachedItemRemovedCallback(CacheEntryRemovedArguments arguments)
{
String strLog = String.Concat("Reason: ", arguments.RemovedReason.ToString(), " | Key-Name: ", arguments.CacheItem.Key, " | Value-Object: ", arguments.CacheItem.Value.ToString());
LogManager.Instance.Info(strLog);
}
}
I use two classes. First one the cache core object:
public class Cacher<TValue>
where TValue : class
{
#region Properties
private Func<TValue> _init;
public string Key { get; private set; }
public TValue Value
{
get
{
var item = HttpRuntime.Cache.Get(Key) as TValue;
if (item == null)
{
item = _init();
HttpContext.Current.Cache.Insert(Key, item);
}
return item;
}
}
#endregion
#region Constructor
public Cacher(string key, Func<TValue> init)
{
Key = key;
_init = init;
}
#endregion
#region Methods
public void Refresh()
{
HttpRuntime.Cache.Remove(Key);
}
#endregion
}
Second one is list of cache objects:
public static class Caches
{
static Caches()
{
Languages = new Cacher<IEnumerable<Language>>("Languages", () =>
{
using (var context = new WordsContext())
{
return context.Languages.ToList();
}
});
}
public static Cacher<IEnumerable<Language>> Languages { get; private set; }
}
I will say implementing Singleton on this persisting data issue can be a solution for this matter in case you find previous solutions much complicated
public class GPDataDictionary
{
private Dictionary<string, object> configDictionary = new Dictionary<string, object>();
/// <summary>
/// Configuration values dictionary
/// </summary>
public Dictionary<string, object> ConfigDictionary
{
get { return configDictionary; }
}
private static GPDataDictionary instance;
public static GPDataDictionary Instance
{
get
{
if (instance == null)
{
instance = new GPDataDictionary();
}
return instance;
}
}
// private constructor
private GPDataDictionary() { }
} // singleton
HttpContext.Current.Cache.Insert("subjectlist", subjectlist);
You can also try and use the caching built into ASP MVC:
Add the following attribute to the controller method you'd like to cache:
[OutputCache(Duration=10)]
In this case the ActionResult of this will be cached for 10 seconds.
More on this here