/// <summary>
/// Commits the header information which essentially commits any transactions that occured
/// related to that header.
/// </summary>
/// <param name="newCommit">the new commit to write</param>
/// <param name="headerStartOffsetBytes">where in the blob the new commit will be written</param>
/// <param name="blob">blob header applies to</param>
/// <param name="header">the new header data</param>
/// <returns></returns>
private void CommitNewMessage(WrappedPageBlob blob, byte[] newCommit, StreamBlobHeader header, int offsetBytes)
{
newCommit = newCommit ?? new byte[0];
var serializedHeader = _serializer.Serialize(header);
var writeStartLocationAligned = GetPageAlignedSize(offsetBytes);
var amountToWriteAligned = GetPageAlignedSize(serializedHeader.Length + newCommit.Length);
var totalSpaceNeeded = writeStartLocationAligned + amountToWriteAligned;
var totalBlobLength = blob.Properties.Length;
if (totalBlobLength < totalSpaceNeeded)
{
blob.Resize(totalSpaceNeeded);
totalBlobLength = blob.Properties.Length;
}
// set the header definition to make it all official
var headerDefinitionMetadata = new HeaderDefinitionMetadata();
headerDefinitionMetadata.HeaderSizeInBytes = serializedHeader.Length;
headerDefinitionMetadata.HeaderStartLocationOffsetBytes = writeStartLocationAligned + newCommit.Length;
blob.Metadata[_isEventStreamAggregateKey] = "yes";
blob.Metadata[_hasUndispatchedCommitsKey] = header.PageBlobCommitDefinitions.Any((x) => !x.IsDispatched).ToString();
if (blob.Metadata.ContainsKey(_primaryHeaderDefinitionKey))
{
blob.Metadata[_fallbackHeaderDefinitionKey] = blob.Metadata[_primaryHeaderDefinitionKey];
}
blob.Metadata[_primaryHeaderDefinitionKey] = Convert.ToBase64String(headerDefinitionMetadata.GetRaw());
blob.SetMetadata();
using (var ms = new MemoryStream(amountToWriteAligned))
{
ms.Write(newCommit, 0, newCommit.Length);
ms.Write(serializedHeader, 0, serializedHeader.Length);
var remainder = (ms.Position % _blobPageSize);
var fillSpace = amountToWriteAligned - newCommit.Length - serializedHeader.Length;
if (fillSpace != 0)
{
ms.Position += fillSpace - 1;
ms.WriteByte(0);
}
ms.Position = 0;
blob.Write(ms, writeStartLocationAligned);
}
}
/// <summary>
/// Commits the header information which essentially commits any transactions that occurred
/// related to that header.
/// </summary>
/// <param name="newCommit">the new commit to write</param>
/// <param name="blob">blob header applies to</param>
/// <param name="updatedHeader">the new header to be serialized out</param>
/// <param name="currentGoodHeaderDefinition">the definition for the current header, before this change is committed</param>
/// <param name="nonAlignedBytesUsedAlready">non aligned offset of index where last commit data is stored (not inclusive of header)</param>
/// <returns></returns>
private void CommitNewMessage(WrappedPageBlob blob, byte[] newCommit,
StreamBlobHeader updatedHeader, HeaderDefinitionMetadata currentGoodHeaderDefinition,
int nonAlignedBytesUsedAlready)
{
newCommit = newCommit ?? new byte[0];
var serializedHeader = _serializer.Serialize(updatedHeader);
var writeStartLocationAligned = GetPageAlignedSize(nonAlignedBytesUsedAlready);
var amountToWriteAligned = GetPageAlignedSize(serializedHeader.Length + newCommit.Length);
var totalSpaceNeeded = writeStartLocationAligned + amountToWriteAligned;
var newHeaderStartLocationNonAligned = writeStartLocationAligned + newCommit.Length;
var totalBlobLength = blob.Properties.Length;
if (totalBlobLength < totalSpaceNeeded)
{
blob.Resize(totalSpaceNeeded);
totalBlobLength = blob.Properties.Length;
}
// set the header definition to make it all official
bool isFirstWrite = currentGoodHeaderDefinition.HeaderSizeInBytes == 0;
var headerDefinitionMetadata = new HeaderDefinitionMetadata();
headerDefinitionMetadata.HeaderSizeInBytes = serializedHeader.Length;
headerDefinitionMetadata.HeaderStartLocationOffsetBytes = writeStartLocationAligned + newCommit.Length;
blob.Metadata[_isEventStreamAggregateKey] = "yes";
blob.Metadata[_hasUndispatchedCommitsKey] = updatedHeader.PageBlobCommitDefinitions.Any((x) => !x.IsDispatched).ToString();
if (!isFirstWrite)
{
blob.Metadata[_secondaryHeaderDefinitionKey] = Convert.ToBase64String(currentGoodHeaderDefinition.GetRaw());
// this is a thirt layer backup in the case we have a issue in the middle of this upcoming write operation.
var tempHeaderDefinition = currentGoodHeaderDefinition.Clone();
tempHeaderDefinition.HeaderStartLocationOffsetBytes = newHeaderStartLocationNonAligned;
blob.Metadata[_terciaryHeaderDefintionKey] = Convert.ToBase64String(tempHeaderDefinition.GetRaw());
blob.Metadata[_firstWriteCompletedKey] = "t";
}
else
{
blob.Metadata[_firstWriteCompletedKey] = "f";
}
blob.Metadata[_primaryHeaderDefinitionKey] = Convert.ToBase64String(headerDefinitionMetadata.GetRaw());
blob.SetMetadata();
using (var ms = CreateAndFillStreamAligned(amountToWriteAligned, newCommit, serializedHeader))
{ blob.Write(ms, writeStartLocationAligned, newHeaderStartLocationNonAligned, currentGoodHeaderDefinition); }
// we pay the cost of an extra call for our first ever write (this is effectively creation of the aggregate.
// we do this because we actually host our header in the blob, but the reference to that header in our metadata.
// we set the metadata with the potential states prior to actually writing the new header. If this was the first
// ever write and we set the metadata, but then fail to write the header, we can get in a state where the aggregate
// becomes unusable because it believes there should be a header according to the metadata.
// For that reason we must record when our first write completes
if (isFirstWrite)
{
blob.Metadata[_firstWriteCompletedKey] = "t";
blob.SetMetadata();
}
}