[ASP.NET Core] In-Memory caching

 ASP.NET Core   In Memory Caching

▌Introduction

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In-memory cache makes faster response and better user experience.

Let’s see how to use it in ASP.NET Core.

▌Environment

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▋.NET Core 2.0.0 preview 1

▌Implement

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▋Register service

▋Startup.cs

public void ConfigureServices(IServiceCollection services) {      services.AddMemoryCache(); }

▋Inject IMemoryCache

▋Controller

private IMemoryCache _cache; public CachedemoController(IMemoryCache memoryCache) {    this._cache = memoryCache; }

I create a Dictionary to store my cache keys.

private IMemoryCache _cache; private Dictionary<string, string> _cacheKeys = null; public CachedemoController(IMemoryCache memoryCache) {      this._cache = memoryCache;      this._cacheKeys = new Dictionary<string, string>();      this._cacheKeys.Add("Datetime1", "Datetime1");      this._cacheKeys.Add("Datetime2", "Datetime2"); }

▋Create or read in-memory cache

DateTime cacheDatetime1; var key = this._cacheKeys["Datetime1"].ToString(); if (!this._cache.TryGetValue(key, out cacheDatetime1)) {    //Get value     cacheDatetime1 = DateTime.Now;    // Set cache options    var cacheEntryOptions = new MemoryCacheEntryOptions()         .SetAbsoluteExpiration(TimeSpan.FromSeconds(5));         //.SetSlidingExpiration(TimeSpan.FromSeconds(5));    // Save data in cache.    _cache.Set(key, cacheDatetime1, cacheEntryOptions); }

                            

The difference between AbsoluteExpiration and SlidingExpiration is,

1.  In SlidingExpiration the expired time will reset to 5 sec again when the cache is hit and not expired.

2.  AbsoluteExpiration means the cache will be cleared definitely after 5 sec.

An easy way to achieve the above goal is using GetOrCreate method, see the following codes.

▋Using GetOrCreate method

var cacheDatetime2 = _cache.GetOrCreate(this._cacheKeys["Datetime2"], entry => {       entry.AbsoluteExpirationRelativeToNow = TimeSpan.FromSeconds(5);       return DateTime.Now; });

▋Just Get

var getDatetime = _cache.Get(this._cacheKeys["Datetime2"]);

▋Sample

I create a sample to show how these methods work.

The full sample codes is as following.

▋View

<h2>Non Cached Datetime : @ViewBag.CurrentDatetime</h2> <h2>Cached Datetime1 : @ViewBag.CurrentDatetime1</h2> <h2>Cached Datetime2 : @ViewBag.CurrentDatetime2</h2>

▋Controller

[Route("[action]")] public IActionResult Now([FromQuery]string clear) {             var clearKey = this._cacheKeys.ToList().TakeWhile(x => x.Key.Equals(clear)).FirstOrDefault();             if (!clearKey.Equals(default(KeyValuePair<string, string>)))             { this._cache.Remove(clearKey.Value); }             #region Traditional way             DateTime cacheDatetime1;             var key = this._cacheKeys["Datetime1"].ToString();             if (!this._cache.TryGetValue(key, out cacheDatetime1))             {                 //Get value                 cacheDatetime1 = DateTime.Now;                 // Set cache options                 var cacheEntryOptions = new MemoryCacheEntryOptions()                     // .SetSlidingExpiration(TimeSpan.FromSeconds(5));                     .SetAbsoluteExpiration(TimeSpan.FromSeconds(5));                 // Save data in cache.                 _cache.Set(key, cacheDatetime1, cacheEntryOptions);             }             #endregion             #region Use GetOrCreate method             var cacheDatetime2 = _cache.GetOrCreate(this._cacheKeys["Datetime2"], entry =>             {                 entry.AbsoluteExpirationRelativeToNow = TimeSpan.FromSeconds(5);                 // entry.SlidingExpiration = TimeSpan.FromSeconds(5);                 return DateTime.Now;             });             #endregion             ViewBag.CurrentDatetime = DateTime.Now.ToString("yyyy/MM/dd HH:mm:ss");             ViewBag.CurrentDatetime1 = cacheDatetime1.ToString("yyyy/MM/dd HH:mm:ss");             ViewBag.CurrentDatetime2 = cacheDatetime2.ToString("yyyy/MM/dd HH:mm:ss");             return View(); }

▋Demo

▌Reference

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▋Introduction to in-memory caching in ASP.NET Core