public async Task Delete(ScaleUpRequestEntity entry)
{
if (entry == null)
{
_logger.LogWarning("ScaleUpStore was asked to delete a null entry, returning");
return;
}
try
{
_logger.LogDebug("Deleting entry '{0}:{1}' from storage", entry.EnvironmentName, entry.PoolName);
var operation = TableOperation.Delete(entry);
await _table.ExecuteAsync(operation);
_logger.LogDebug("Entry '{0}:{1}' deleted", entry.EnvironmentName, entry.PoolName);
}
catch (StorageException ex) when(ex.RequestInformation.HttpStatusCode == 404)
{
// whole table is gone
}
catch (Exception ex)
{
// TODO: correctly handle this. This may fail due to eTag.
// if so read it again and delete.
_logger.LogError(ex, "Failed to delete storage entry");
}
}
public async Task Add(string envName, string poolName, int requested)
{
async Task AddRequest()
{
var scaleUpEntry = await Get(envName, poolName, CancellationToken.None);
if (scaleUpEntry == null)
{
// no entry exists so add it
scaleUpEntry =
new ScaleUpRequestEntity(envName, poolName)
{
TargetNodes = requested,
};
await InsertOrMergeEntry(scaleUpEntry);
}
else
{
bool changed = false;
if (requested > scaleUpEntry.TargetNodes)
{
changed = true;
scaleUpEntry.TargetNodes = requested;
}
// if limits were lower then the request is ignored
if (changed)
{
await InsertOrMergeEntry(scaleUpEntry);
}
}
}
// we will attempt up to 5 times
// this should be plenty as there is a large delay on the processor side
StorageException lastEx = null;
for (int i = 0; i < 5; ++i)
{
try
{
await AddRequest();
return;
}
catch (StorageException ex)
when(ex.RequestInformation.HttpStatusCode == (int)HttpStatusCode.PreconditionFailed)
{
// etag mismatch, try again
lastEx = ex;
}
}
// give up:
_logger.LogError(lastEx, "Unable to insert scale request");
throw lastEx;
}
private async Task InsertOrMergeEntry(ScaleUpRequestEntity entry)
{
// TODO: catch and retry if it fails as another request could have already added one
// for the same environment and pool
await _table.CreateIfNotExistsAsync();
var operation = TableOperation.InsertOrMerge(entry);
await _table.ExecuteAsync(operation);
}
