public ITransaction Setup(IEnumerable <object> items)
{
var txnEntries = items.Select(x =>
{
var type = x.GetType().Name;
var id = _idAccessor.GetId(x)?.ToString();
var rev = _revisionAccessor.GetRevision(x)?.ToString();
var txn = new TransactionEntry()
{
DateTime = DateTime.UtcNow,
Id = $"{id}-{type}",
ActualId = id,
ActualRev = rev,
Type = type
};
return(txn);
});
var transaction = new Transaction(_couchDb, _idAccessor, _revisionAccessor);
try
{
transaction.Init(txnEntries);
}
catch (Exception e)
{
transaction.Rollback(e);
throw;
}
return(transaction);
}
public Task Execute(IEnumerable <CommitContext> items, Next <IEnumerable <CommitContext> > next)
{
items = items.ToList(); //ensure 1 iteration over list. (tasks to run once)
//do not call the db if we have no items to transact on.
if (!items.Any())
{
return(Task.CompletedTask);
}
//setup the items for the database commit.
var entityUpdates = new Dictionary <string, object>();
var docRequests = new List <BulkDocRequest>();
foreach (var bulkContext in items)
{
var entry = new BulkDocRequest
{
Content = bulkContext.Entity,
Id = bulkContext.Key.CouchDbId
};
switch (bulkContext.ActionType)
{
case ActionType.Add:
break;
case ActionType.Update:
break;
case ActionType.Delete:
entry.Rev = (string)_revisionAccessor.GetRevision(bulkContext.Entity);
entry.Delete = true;
break;
default:
throw new ArgumentOutOfRangeException();
}
docRequests.Add(entry);
entityUpdates.Add(entry.Id, bulkContext.Entity);
}
//apply the commit
var request = new BulkDocsRequest {
Docs = docRequests
};
var updates = _couchDb.BulkApplyChanges(request);
//update any revisions!
foreach (var update in updates)
{
var entity = entityUpdates[update.Id];
_revisionAccessor.SetRevision(entity, update.Rev);
}
return(Task.CompletedTask);
}
public void Init(IEnumerable <TransactionEntry> txnEntries)
{
_txnEntries = new Dictionary <string, TransactionEntry>();
foreach (var txnEntry in txnEntries)
{
txnEntry.TransactionId = _id;
_txnEntries.Add(txnEntry.ActualId, txnEntry);
}
var now = DateTime.UtcNow;
bool HasExpired(DateTime time) => new TimeSpan(now.Ticks - time.Ticks).TotalSeconds > 5;
var existingTransactionEntries = _couchDb
.LoadAllEntities(
new AllDocsRequest()
{
Keys = _txnEntries.Values.Select(x => x.Id) //checking against transaction key for documents
})
.Rows
.Select(x => x.Doc)
.Cast <TransactionEntry>()
.ToList();
var hasTransactionLockConflict = existingTransactionEntries.Any(x => HasExpired(x.DateTime));
if (hasTransactionLockConflict)
{
throw new TransactionException(existingTransactionEntries.Select(x => x.Id).ToList());
}
var payload = new BulkDocsRequest()
{
Docs = _txnEntries.Values.Select(
txn => new BulkDocRequest()
{
Id = txn.Id,
Content = txn
})
};
_results = _couchDb.BulkApplyChanges(payload).ToList();
//now we have a txn (lock) we confirm the target docs are still on the same rev
var conflictingDocs = _couchDb.LoadAllEntities(
new AllDocsRequest()
{
Keys = _txnEntries.Values.Select(x => x.ActualId)
})
.Rows
.Select(x => x.Doc)
.Select(x => new
{
Id = _idAccessor.GetId(x).ToString(),
Rev = _revisionAccessor.GetRevision(x)?.ToString()
})
.Where(x =>
{
if (!_txnEntries.TryGetValue(x.Id, out var entry))
{
return(false);
}
return(entry.ActualRev != x.Rev);
})
.ToList();
if (conflictingDocs.Any())
{
throw new AggregateException(conflictingDocs.Select(x => new ConflictException(x.Id, x.Rev, "conflict", "stale reference")));
}
}