gistfile1.cs

using DistributedMutex;
using Microsoft.WindowsAzure.Storage;
using System;
using System.Collections.Generic;
using System.Configuration;
using System.Diagnostics;
using System.Linq;
using System.Threading;
using System.Threading.Tasks;
using System.Web;
using System.Web.Mvc;

namespace LbsTest.Controllers
{
    public class HomeController : Controller
    {
        public async Task<ActionResult> ProbeEndpoint()
        {
            string leaseId = string.Empty; 
            CloudStorageAccount storageAccount = CloudStorageAccount.Parse(ConfigurationManager.ConnectionStrings["CsaMutex"].ConnectionString);
            string container = ConfigurationManager.AppSettings["CsaMutexContainer"];
            string blobName = ConfigurationManager.AppSettings["CsaMutexBlob"];
            BlobSettings blobSettings = new BlobSettings(storageAccount, container, blobName); 
            CancellationToken token = new CancellationToken(false);
            BlobLeaseManager leaseManager = new BlobLeaseManager(blobSettings);

            // Get the lease from the application state
            leaseId = GetCachedLeaseId();

            // If we could not get the lease from application state try to acquire the blob lease
            if (string.IsNullOrEmpty(leaseId))
            {
                leaseId = await leaseManager.AcquireLeaseAsync(token);

                // Cache the lease id
                SetCachedLeaseId(leaseId);
            }

            // Try to Renew the lease
            // If you cannot clear the cache
            if (!string.IsNullOrEmpty(leaseId))
            {
                if (await leaseManager.RenewLeaseAsync(leaseId, token))
                {
                    return new HttpStatusCodeResult(System.Net.HttpStatusCode.OK);
                }
                else 
                {
                    SetCachedLeaseId(string.Empty);
                }
            }
            
            return new HttpStatusCodeResult(System.Net.HttpStatusCode.ServiceUnavailable);
        }

        private void SetCachedLeaseId(string leaseId)
        {
            System.Web.HttpContext.Current.Application.Lock();
            System.Web.HttpContext.Current.Application["leaseId"] = leaseId;
            System.Web.HttpContext.Current.Application.UnLock();        
        }

        private string GetCachedLeaseId()
        {
            string leaseId = string.Empty;
            System.Web.HttpContext.Current.Application.Lock();
            if (System.Web.HttpContext.Current.Application["leaseId"] != null)
            {
                leaseId = System.Web.HttpContext.Current.Application["leaseId"].ToString();
            };
            System.Web.HttpContext.Current.Application.UnLock();
            return leaseId;
        }

    }
}