a-azure-lock

A blob lock written in ASP.NET and C# to use in multi-instance applications on Azure. A blob lock needs a connection string to the storage account, a container name and a name for the blob file, these settings is added as options to the constructor.

You can upload a stream of content to the locked cloud block blob and download the contents from the locked cloud block blob as a stream. You can write text to and read text from the locked cloud block blob.

If you want to test the lock with the test program, add a appsettings.Development.json (copy of appsettings.json) or modify the appsettings.json file.

This blob lock is available as a NuGet package: a-azure-lock (NuGet Gallery)

Example, Create a lock or wait for the lock to be released:

// Add options
BlobLockOptions options = new BlobLockOptions();
options.connection_string = this.configuration.GetSection("AppSettings")["AzureStorageAccount"];
options.container_name = "test-locks";
options.blob_name = "test.lck";

// Use a blob lock, the lock is disposed by the using block
using (BlobLock blobLock = new BlobLock(options))
{
	// Do work inside a blob lock
	if (await blobLock.CreateOrWait() == true)
	{
		Logger.LogMessage("Thread " + threadId.ToString() + ": Has lock for 1 minute. Date: " + DateTime.UtcNow.ToString("s"));

		// Read from the blob
		Logger.LogMessage("Text: " + await blobLock.ReadFrom());

		// Sleep for 1 minute
		await Task.Delay(TimeSpan.FromSeconds(60));
	}
}

Example, Create a lock or skip if the lock is taken:

// Add options
BlobLockOptions options = new BlobLockOptions();
options.connection_string = this.configuration.GetSection("AppSettings")["AzureStorageAccount"];
options.container_name = "test-locks";
options.blob_name = "test.lck";

// Use a blob lock, the lock is disposed by the using block
using (BlobLock blobLock = new BlobLock(options))
{
	// Do work inside a blob lock
	if (await blobLock.CreateOrSkip() == true)
	{
		Logger.LogMessage("Thread " + threadId.ToString() + ": Has lock for 1 minute.");

		// Sleep for 1 minute
		await Task.Delay(TimeSpan.FromSeconds(60));

		// Write to the blob
		await blobLock.WriteTo(threadId.ToString());
	}
	else
	{
		Logger.LogMessage("Thread " + threadId.ToString() + ": Does not wait for the lock to be released.");
	}
}

Example, Upload a stream (image):

// Add options
BlobLockOptions options = new BlobLockOptions()
{
	connection_string = this.configuration.GetSection("AppSettings")["AzureStorageAccount"],
	container_name = "test-locks",
	blob_name = "image.jpg"
};

// Use a blob lock, the lock is disposed by the using block
using (BlobLock blobLock = new BlobLock(options))
{
	// Do work inside a blob lock
	if (await blobLock.CreateOrSkip() == true)
	{
		Logger.LogMessage("Thread " + threadId.ToString() + ": Has lock for 1 minute.");

		// Upload the image
		using (FileStream fileStream = File.OpenRead("D:\\Bilder\\1960.jpg"))
		{
			await blobLock.WriteTo(fileStream);
		}

		Logger.LogMessage("Thread " + threadId.ToString() + ": Image has been uploaded.");
	}
	else
	{
		Logger.LogMessage("Thread " + threadId.ToString() + ": Does not wait for the lock to be released.");
	}
}

Example, Download a stream (image):

// Add options
BlobLockOptions options = new BlobLockOptions()
{
	connection_string = this.configuration.GetSection("AppSettings")["AzureStorageAccount"],
	container_name = "test-locks",
	blob_name = "image.jpg"
};

// Use a blob lock, the lock is disposed by the using block
using (BlobLock blobLock = new BlobLock(options))
{
	// Do work inside a blob lock
	if (await blobLock.CreateOrSkip() == true)
	{
		Logger.LogMessage("Thread " + threadId.ToString() + ": Has lock for 1 minute.");

		// Download an image to a file
		using (FileStream fileStream = File.OpenWrite("D:\\Bilder\\Azure-blob-image.jpg"))
		{
			await blobLock.ReadFrom(fileStream);
		}

		Logger.LogMessage("Thread " + threadId.ToString() + ": Image has been downloaded.");
	}
	else
	{
		Logger.LogMessage("Thread " + threadId.ToString() + ": Does not wait for the lock to be released.");
	}
}