Merge pull request #10 from ppluijten/master

Checking if append blobs exist before appending to them

Author: ob1dev

src/Sitecore.Azure.Diagnostics/Appenders/AzureBlobStorageAppender.cs

@@ -4,6 +4,7 @@
 using System.Linq;
 using log4net.Appender;
 using log4net.spi;
+using Microsoft.WindowsAzure.Storage;
 using Microsoft.WindowsAzure.Storage.Blob;
 using Sitecore.Azure.Diagnostics.Storage;
 
@@ -105,9 +106,25 @@ protected override void Append(LoggingEvent loggingEvent)
       var blob = this.Blob as CloudAppendBlob;
       string message = this.RenderLoggingEvent(loggingEvent);
 
+      CreateBlobIfNotExists(blob);
       blob.AppendText(message);
     }    
 
+    /// <summary>
+    /// Creates a new blob for the specified <see cref="CloudAppendBlob" /> if it does not already exist.
+    /// </summary>
+    /// <param name="blob">The <see cref="CloudAppendBlob" />.</param>
+    /// <param name="accessCondition">The access condition.</param>
+    /// <param name="blobRequestOptions">The blob request options.</param>
+    /// <param name="operationContext">The operation context.</param>
+    protected static void CreateBlobIfNotExists(CloudAppendBlob blob, AccessCondition accessCondition = null, BlobRequestOptions blobRequestOptions = null, OperationContext operationContext = null)
+    {
+        if (!blob.Exists(blobRequestOptions, operationContext))
+        {
+            blob.CreateOrReplace(accessCondition, blobRequestOptions, operationContext);
+        }
+    }
+
     /// <summary>
     /// Gets the new cloud blob for diagnostic messages.
     /// </summary>