name / image / info -data in Profile is broken, with high probability that it is because of stopping the node.

[chhsiao1981]

Version information:

Gptt
Version: 0.2.0
Git Commit: 6ffbb92
Architecture: amd64
Go Version: go1.11.1
Operating System: linux

Type:

Bug

Description:

Sometimes the data of name / image / info in Profile is broken and unavailable to access.
Need to check:

1. What happened to the underlying raw data in db.
2. Is it because of not correct implementation in graceful shutdown?
3. Or something went wrong when syncing？～
4. Or how to know that some data is broken？～ (able to get data, but unable to unmarshal)
5. How to do resync when data is broken？

#240

[chhsiao1981]

1. Found the following anomaly record:

key: b'.urig\xed\xf1\xf8r\x11\r\xf5\x96\xb8\xa7\x00\xde\xb35\xe3\x92\x07\x92\xeb\xc1 \xe9\xaa\xfb\x95\xc1\x93$\xe8[ )9G\x80\xa21:\xdf\x8e\xd05\xfev,>i\xbfzs\xc4\x16\x16\xd3fc\xa1k\x9cY"\xc8\xe9\xc6\x02\x88\x1d\xe3=\x9fj\xcc*.b8\xc9\K\x1b'

val: b'QMT/F7NeOCmJq6SQN9lX891EuO"],"UT":{"T":1551919303,"NT":863591202}}\x01-.umdb\xcc\x9cF)|\xa5F\o\xf3\x9a\x93k\xca]d7\x106\xbc\x04\x0cO\xf1{5\xe3\x82\x98\x9a\xbaI\x03}\x95\x7f=\xd4K\x8e\xf5\x03{"b":{"V":2,"ID":"BAfNMz9ioVj1Kq87CuUk83HG2qiAc9Wk8ts5LFVxSHAbQwHme'

The data is corrupted.

Strangely only the account-data is corrupted.
It's possible that it's due to that the account information is excessively accessed and some race condition happened when shutting-down the node.

2. Found that DBUserNodeInfoPrefix is assigned incorrectly, conflict with DBUserImgPrefix.

TODO:

1. fix DBUserNodeInfoPrefix.
2. change the setup and do not close the DB in stop.

[chhsiao1981]

Found more fundamental issue about pttdb:

We use LDBBatch for most of db-operation, but it looks like Batch is not threadsafe (Batch.Put and Batch.Reset)

Need to fix the db-operation first:

For LDBBatch.PutAllWithKeyIndex, LDBBatch.PutAll, LDBBatch.TryPutAll, LDBBatch.TryPutAllSameUT, LDBBatch.ForcePutAll: have new leveldb.Batch in every call of the functions.

https://github.com/ailabstw/go-pttai/blob/master/pttdb/ldb_database.go

https://github.com/syndtr/goleveldb/blob/master/leveldb/batch.go#L163

[chhsiao1981]

Confirmed that unable to send packet over 64k.

The max size of our packet may lead to 10M.
We need to segment the packets before sending the data.

https://github.com/pion/sctp/blob/master/stream.go#L146
(from https://github.com/pion/datachannel/blob/master/datachannel.go#L262)
(from https://github.com/ailabstw/go-pttai/blob/master/p2p/webrtc/webrtc_conn.go#L91)