LeaseExtensions.cs

using Microsoft.WindowsAzure.StorageClient;
using Microsoft.WindowsAzure.StorageClient.Protocol;
using System;
using System.IO;
using System.Threading;
using System.Net;

namespace smarx.WazStorageExtensions
{
    public static class LeaseBlobExtensions
    {
        public static string TryAcquireLease(this CloudBlob blob)
        {
            try { return blob.AcquireLease(); }
            catch (WebException e)
            {
                if ((e.Response == null) || ((HttpWebResponse)e.Response).StatusCode != HttpStatusCode.Conflict) // 409, already leased
                {
                    throw;
                }
                e.Response.Close();
                return null;
            }
        }

        public static string AcquireLease(this CloudBlob blob)
        {
            var creds = blob.ServiceClient.Credentials;
            var transformedUri = new Uri(creds.TransformUri(blob.Uri.AbsoluteUri));
            var req = BlobRequest.Lease(transformedUri,
                90, // timeout (in seconds)
                LeaseAction.Acquire, // as opposed to "break" "release" or "renew"
                null); // name of the existing lease, if any
            blob.ServiceClient.Credentials.SignRequest(req);
            using (var response = req.GetResponse())
            {
                return response.Headers["x-ms-lease-id"];
            }
        }

        private static void DoLeaseOperation(CloudBlob blob, string leaseId, LeaseAction action)
        {
            var creds = blob.ServiceClient.Credentials;
            var transformedUri = new Uri(creds.TransformUri(blob.Uri.AbsoluteUri));
            var req = BlobRequest.Lease(transformedUri, 90, action, leaseId);
            creds.SignRequest(req);
            req.GetResponse().Close();
        }

        public static void ReleaseLease(this CloudBlob blob, string leaseId)
        {
            DoLeaseOperation(blob, leaseId, LeaseAction.Release);
        }

        public static bool TryRenewLease(this CloudBlob blob, string leaseId)
        {
            try { blob.RenewLease(leaseId); return true; }
            catch { return false; }
        }

        public static void RenewLease(this CloudBlob blob, string leaseId)
        {
            DoLeaseOperation(blob, leaseId, LeaseAction.Renew);
        }

        public static void BreakLease(this CloudBlob blob)
        {
            DoLeaseOperation(blob, null, LeaseAction.Break);
        }

        // NOTE: This method doesn't do everything that the regular UploadText does.
        // Notably, it doesn't update the BlobProperties of the blob (with the new
        // ETag and LastModifiedTimeUtc). It also, like all the methods in this file,
        // doesn't apply any retry logic. Use this at your own risk!
        public static void UploadText(this CloudBlob blob, string text, string leaseId)
        {
            string url = blob.Uri.AbsoluteUri;
            if (blob.ServiceClient.Credentials.NeedsTransformUri)
            {
                url = blob.ServiceClient.Credentials.TransformUri(url);
            }
            var req = BlobRequest.Put(new Uri(blob.ServiceClient.Credentials.TransformUri(blob.Uri.AbsoluteUri)),
                90, new BlobProperties(), BlobType.BlockBlob, leaseId, 0);
            using (var writer = new StreamWriter(req.GetRequestStream()))
            {
                writer.Write(text);
            }
            blob.ServiceClient.Credentials.SignRequest(req);
            req.GetResponse().Close();
        }

        public static void SetMetadata(this CloudBlob blob, string leaseId)
        {
            var req = BlobRequest.SetMetadata(new Uri(blob.ServiceClient.Credentials.TransformUri(blob.Uri.AbsoluteUri)), 90, leaseId);
            foreach (string key in blob.Metadata.Keys)
            {
                req.Headers.Add("x-ms-meta-" + key, blob.Metadata[key]);
            }
            blob.ServiceClient.Credentials.SignRequest(req);
            req.GetResponse().Close();
        }
    }
}