public async Task <FunctionResult> ExecuteAsync(IStorageBlob value, CancellationToken cancellationToken)
{
// Avoid unnecessary network calls for non-matches. First, check to see if the blob matches this trigger.
IReadOnlyDictionary <string, object> bindingData = _input.CreateBindingData(value.ToBlobPath());
if (bindingData == null)
{
// Blob is not a match for this trigger.
return(new FunctionResult(true));
}
// Next, check to see if the blob currently exists (and, if so, what the current ETag is).
string possibleETag = await _eTagReader.GetETagAsync(value, cancellationToken);
if (possibleETag == null)
{
// If the blob doesn't exist and have an ETag, don't trigger on it.
return(new FunctionResult(true));
}
IStorageBlockBlob receiptBlob = _receiptManager.CreateReference(_hostId, _functionId, value.Container.Name,
value.Name, possibleETag);
// Check for the completed receipt. If it's already there, noop.
BlobReceipt unleasedReceipt = await _receiptManager.TryReadAsync(receiptBlob, cancellationToken);
if (unleasedReceipt != null && unleasedReceipt.IsCompleted)
{
return(new FunctionResult(true));
}
else if (unleasedReceipt == null)
{
// Try to create (if not exists) an incomplete receipt.
if (!await _receiptManager.TryCreateAsync(receiptBlob, cancellationToken))
{
// Someone else just created the receipt; wait to try to trigger until later.
// Alternatively, we could just ignore the return result and see who wins the race to acquire the
// lease.
return(new FunctionResult(false));
}
}
string leaseId = await _receiptManager.TryAcquireLeaseAsync(receiptBlob, cancellationToken);
if (leaseId == null)
{
// If someone else owns the lease and just took over this receipt or deleted it;
// wait to try to trigger until later.
return(new FunctionResult(false));
}
ExceptionDispatchInfo exceptionInfo;
try
{
// Check again for the completed receipt. If it's already there, noop.
BlobReceipt receipt = await _receiptManager.TryReadAsync(receiptBlob, cancellationToken);
Debug.Assert(receipt != null); // We have a (30 second) lease on the blob; it should never disappear on us.
if (receipt.IsCompleted)
{
await _receiptManager.ReleaseLeaseAsync(receiptBlob, leaseId, cancellationToken);
return(new FunctionResult(true));
}
// We've successfully acquired a lease to enqueue the message for this blob trigger. Enqueue the message,
// complete the receipt and release the lease.
// Enqueue a message: function ID + blob path + ETag
BlobTriggerMessage message = new BlobTriggerMessage
{
FunctionId = _functionId,
BlobType = value.BlobType,
ContainerName = value.Container.Name,
BlobName = value.Name,
ETag = possibleETag
};
await _queueWriter.EnqueueAsync(message, cancellationToken);
// Complete the receipt & release the lease
await _receiptManager.MarkCompletedAsync(receiptBlob, leaseId, cancellationToken);
await _receiptManager.ReleaseLeaseAsync(receiptBlob, leaseId, cancellationToken);
return(new FunctionResult(true));
}
catch (Exception exception)
{
exceptionInfo = ExceptionDispatchInfo.Capture(exception);
}
Debug.Assert(exceptionInfo != null);
await _receiptManager.ReleaseLeaseAsync(receiptBlob, leaseId, cancellationToken);
exceptionInfo.Throw();
FunctionResult result = new FunctionResult(exceptionInfo.SourceException);
return(result); // Keep the compiler happy; we'll never get here.
}
public async Task <FunctionResult> ExecuteAsync(BlobTriggerExecutorContext context, CancellationToken cancellationToken)
{
BlobBaseClient value = context.Blob.BlobClient;
BlobTriggerScanSource triggerSource = context.TriggerSource;
string pollId = context.PollId;
// Avoid unnecessary network calls for non-matches. First, check to see if the blob matches this trigger.
IReadOnlyDictionary <string, object> bindingData = _input.CreateBindingData(value.ToBlobPath());
if (bindingData == null)
{
string pattern = new BlobPath(_input.ContainerNamePattern, _input.BlobNamePattern).ToString();
Logger.BlobDoesNotMatchPattern(_logger, _functionDescriptor.LogName, value.Name, pattern, pollId, triggerSource);
// Blob is not a match for this trigger.
return(new FunctionResult(true));
}
// Next, check to see if the blob currently exists (and, if so, what the current ETag is).
BlobProperties blobProperties = await value.FetchPropertiesOrNullIfNotExistAsync(cancellationToken).ConfigureAwait(false);
string possibleETag = null;
if (blobProperties != null)
{
possibleETag = blobProperties.ETag.ToString();
}
if (possibleETag == null)
{
Logger.BlobHasNoETag(_logger, _functionDescriptor.LogName, value.Name, pollId, triggerSource);
// If the blob doesn't exist and have an ETag, don't trigger on it.
return(new FunctionResult(true));
}
var receiptBlob = _receiptManager.CreateReference(_hostId, _functionDescriptor.Id, value.BlobContainerName,
value.Name, possibleETag);
// Check for the completed receipt. If it's already there, noop.
BlobReceipt unleasedReceipt = await _receiptManager.TryReadAsync(receiptBlob, cancellationToken).ConfigureAwait(false);
if (unleasedReceipt != null && unleasedReceipt.IsCompleted)
{
Logger.BlobAlreadyProcessed(_logger, _functionDescriptor.LogName, value.Name, possibleETag, pollId, triggerSource);
return(new FunctionResult(true));
}
else if (unleasedReceipt == null)
{
// Try to create (if not exists) an incomplete receipt.
if (!await _receiptManager.TryCreateAsync(receiptBlob, cancellationToken).ConfigureAwait(false))
{
// Someone else just created the receipt; wait to try to trigger until later.
// Alternatively, we could just ignore the return result and see who wins the race to acquire the
// lease.
return(new FunctionResult(false));
}
}
string leaseId = await _receiptManager.TryAcquireLeaseAsync(receiptBlob, cancellationToken).ConfigureAwait(false);
if (leaseId == null)
{
// If someone else owns the lease and just took over this receipt or deleted it;
// wait to try to trigger until later.
return(new FunctionResult(false));
}
try
{
// Check again for the completed receipt. If it's already there, noop.
BlobReceipt receipt = await _receiptManager.TryReadAsync(receiptBlob, cancellationToken).ConfigureAwait(false);
Debug.Assert(receipt != null); // We have a (30 second) lease on the blob; it should never disappear on us.
if (receipt.IsCompleted)
{
Logger.BlobAlreadyProcessed(_logger, _functionDescriptor.LogName, value.Name, possibleETag, pollId, triggerSource);
await _receiptManager.ReleaseLeaseAsync(receiptBlob, leaseId, cancellationToken).ConfigureAwait(false);
return(new FunctionResult(true));
}
// We've successfully acquired a lease to enqueue the message for this blob trigger. Enqueue the message,
// complete the receipt and release the lease.
// Enqueue a message: function ID + blob path + ETag
BlobTriggerMessage message = new BlobTriggerMessage
{
FunctionId = _functionDescriptor.Id,
BlobType = blobProperties.BlobType,
ContainerName = value.BlobContainerName,
BlobName = value.Name,
ETag = possibleETag
};
var(queueName, messageId) = await _queueWriter.EnqueueAsync(message, cancellationToken).ConfigureAwait(false);
Logger.BlobMessageEnqueued(_logger, _functionDescriptor.LogName, value.Name, messageId, queueName, pollId, triggerSource);
// Complete the receipt
await _receiptManager.MarkCompletedAsync(receiptBlob, leaseId, cancellationToken).ConfigureAwait(false);
return(new FunctionResult(true));
}
finally
{
await _receiptManager.ReleaseLeaseAsync(receiptBlob, leaseId, cancellationToken).ConfigureAwait(false);
}
}