//提交
private void CommitTransfer(TransactionDocument txn, TimeSpan maxTxnTime)
{
DateTime now = DateTime.Now.ToUniversalTime();
DateTime cutOff = now - maxTxnTime;
//更新事务文档
FilterDefinitionBuilder <TransactionDocument> filterBuilder = Builders <TransactionDocument> .Filter;
FilterDefinition <TransactionDocument> filter1 = filterBuilder.Eq(m => m._id, txn._id);
FilterDefinition <TransactionDocument> filter2 = filterBuilder.Gt(m => m.Ts, cutOff);
FilterDefinition <TransactionDocument> filter = filterBuilder.And(new FilterDefinition <TransactionDocument>[] { filter1, filter2 });
var update = Builders <TransactionDocument> .Update.Set(m => m.State, "commit");
UpdateResult updateResult = mongoDBService.DocumentUpdate(TransactionCollectionName, filter, update);
bool isSuccess = updateResult.ModifiedCount > 0 && updateResult.ModifiedCount == updateResult.MatchedCount ?
true : false;
if (!isSuccess)
{
throw new Exception("修改事务文档失败");
}
else
{
RetireTransaction(txn);
}
}
//准备转账
private TransactionDocument PrepareTransfer(double amt, string source, string destination)
{
string strGUID = System.Guid.NewGuid().ToString("N"); //类似e0a953c3ee6040eaa9fae2b667060e09
//创建事务文档
TransactionDocument tDoc = new TransactionDocument
{
_id = strGUID, //这个应该是随机生成的一个串
State = "new",
Ts = DateTime.Now,
Amt = amt,
Src = source,
Dst = destination
};
//将事务文档插入事务集合
bool isSu = mongoDBService.Insert(TransactionCollectionName, tDoc);
if (!isSu)
{
throw new Exception("构建事务文档失败！");
}
FilterDefinitionBuilder <Account> filterBuilder = Builders <Account> .Filter;
//更新source账户
FilterDefinition <Account> filterS = filterBuilder.Eq(m => m._id, source) & filterBuilder.Gte(m => m.Balance, amt);
UpdateDefinition <Account> updateS = Builders <Account> .Update.Push(m => m.Txns, tDoc._id).Inc(m => m.Balance, -amt);
UpdateResult updateResult = mongoDBService.DocumentUpdate(AccountsCollectionName, filterS, updateS);
//检测更新是否成功
bool isSuccess = updateResult.ModifiedCount > 0 && updateResult.ModifiedCount == updateResult.MatchedCount?
true:false;
if (!isSuccess)
{
mongoDBService.Delete <TransactionDocument>(TransactionCollectionName, m => m._id == tDoc._id);
throw new Exception("更新source账户失败");
}
//更新destination账户
FilterDefinition <Account> filterD = filterBuilder.Eq(m => m._id, destination);
var updateD = Builders <Account> .Update.Push(m => m.Txns, tDoc._id).Inc(m => m.Balance, amt);
UpdateResult updateResultD = mongoDBService.DocumentUpdate(AccountsCollectionName, filterD, updateD);
bool isSuccessD = updateResultD.ModifiedCount > 0 && updateResultD.ModifiedCount == updateResultD.MatchedCount ?
true : false;
if (!isSuccessD)
{
throw new Exception("更新destination账户失败");
}
return(tDoc);
}
public void Transfer(double amt, string source, string destination, TimeSpan maxTxnTime)
{
try
{
//准备转账
TransactionDocument txn = PrepareTransfer(amt, source, destination);
CommitTransfer(txn, maxTxnTime);
}
catch (Exception ex)
{
Console.WriteLine(ex.Message);
}
}
//收回事务
//事务收回方法也是幂等的
private void RetireTransaction(TransactionDocument txn)
{
FilterDefinitionBuilder <Account> filterBuilder = Builders <Account> .Filter;
FilterDefinition <Account> filter = filterBuilder.Eq(m => m._id, txn.Src);//source
var update = Builders <Account> .Update.Pull(m => m.Txns, txn._id);
mongoDBService.DocumentUpdate(AccountsCollectionName, filter, update);
FilterDefinition <Account> filterD = filterBuilder.Eq(m => m._id, txn.Dst);//dest
var updateD = Builders <Account> .Update.Pull(m => m.Txns, txn._id);
mongoDBService.DocumentUpdate(AccountsCollectionName, filterD, updateD);
mongoDBService.Delete <TransactionDocument>(TransactionCollectionName, m => m._id == txn._id);
}
//回滚
//这里的回滚方法是“幂等的”
private void RollbackTransfer(TransactionDocument txn)
{
//恢复账户信息
FilterDefinitionBuilder <Account> filterBuilder = Builders <Account> .Filter;
FilterDefinition <Account> filter1 = filterBuilder.Eq(m => m._id, txn.Src);//source
FilterDefinition <Account> filter2 = filterBuilder.Where(m => m.Txns.Contains(txn._id));
FilterDefinition <Account> filter = filterBuilder.And(new FilterDefinition <Account>[] { filter1, filter2 });
var update = Builders <Account> .Update.Inc(m => m.Balance, txn.Amt).Pull(m => m.Txns, txn._id);
mongoDBService.DocumentUpdate(AccountsCollectionName, filter, update);
FilterDefinition <Account> filterD1 = filterBuilder.Eq(m => m._id, txn.Dst);//dest
FilterDefinition <Account> filterD2 = filterBuilder.Where(m => m.Txns.Contains(txn._id));
FilterDefinition <Account> filterD = filterBuilder.And(new FilterDefinition <Account>[] { filterD1, filterD2 });
var updateD = Builders <Account> .Update.Inc(m => m.Balance, -txn.Amt).Pull(m => m.Txns, txn._id);
mongoDBService.DocumentUpdate(AccountsCollectionName, filterD, updateD);
//删除事务文档
mongoDBService.Delete <TransactionDocument>(TransactionCollectionName, m => m._id == txn._id);
}