PlayerList bug makes players invisible.

[BillSchumacher]

Client version: 1.12.2
Server OS: Windows/Linux/macOS/BSD/...
Commit id: 0dd172b (Found at the top of the server's console output)

Expected behavior

Connected players should see new players.
All players should appear in player list and be visible

Actual behavior

Only new players see connected players.
One player appears in player list.

Steps to reproduce the behavior

Compile and run. Connect two clients.

Working on it, will submit PR when I got it figured out.

[BillSchumacher]

Update

On Cuberite players had changed worlds a few times and teleported, I get different output from a fresh install.

Using pyCraft I have verified that connected clients do not receive any "player list item" packets when another user connects after failure condition is reached.

I also tested with a fresh spigot server and a fresh cuberite server.

Logs (SpigotMC):

Connected

1512198818.81 0x23 JoinGamePacket {'entity_id': 651, 'reduced_debug_info': False, 'difficulty': 1, 'game_mode': 0, 'max_players': 20, 'level_type': u'default', 'dimension': 0}
Position: 1
Data: {"extra":[{"color":"yellow","text":"Connect_Player joined the game"}],"text":""}

(u'Connected_Player', 0, 0, None)
('list action: ', 0)
1512198818.81 0x2E PlayerListItemPacket

(u'Connected_Player', 0, 0, None)
('list action: ', 0)
1512198818.81 0x2E PlayerListItemPacket

1512198819.21 0x2F PlayerPositionAndLookPacket {'teleport_id': 1, 'yaw': 2.7448678016662598, 'flags': 0, 'pitch': 0.0, 'y': 64.0, 'x': 240.5, 'z': 230.5}

('list action: ', 1)
1512198827.86 0x2E PlayerListItemPacket

('list action: ', 1)
1512198827.86 0x2E PlayerListItemPacket

Position: 1
Data: {"extra":[{"color":"yellow","text":"New_Player joined the game"}],"text":""}
(u'New_Player', 0, 0, None)
('list action: ', 0)
1512198827.86 0x2E PlayerListItemPacket

('list action: ', 4)
1512198833.49 0x2E PlayerListItemPacket
Position: 1
Data: {"extra":[{"color":"yellow","text":"New_Player left the game"}],"text":""}

('list action: ', 2)
1512198834.28 0x2E PlayerListItemPacket

New Player

1512198827.84 0x23 JoinGamePacket {'entity_id': 720, 'reduced_debug_info': False, 'difficulty': 1, 'game_mode': 0, 'max_players': 20, 'level_type': u'default', 'dimension': 0}
Position: 1
Data: {"extra":[{"color":"yellow","text":"New_Player joined the game"}],"text":""}

(u'Connected_Player', 0, 141, None)
('list action: ', 0)
1512198827.84 0x2E PlayerListItemPacket

(u'New_Player', 0, 0, None)
('list action: ', 0)
1512198827.84 0x2E PlayerListItemPacket

(u'New_Player', 0, 0, None)
('list action: ', 0)
1512198827.84 0x2E PlayerListItemPacket

1512198828.5 0x2F PlayerPositionAndLookPacket {'teleport_id': 1, 'yaw': -35.718074798583984, 'flags': 0, 'pitch': 5.100000381469727, 'y': 64.0, 'x': 251.5, 'z': 242.5}
^CBye!

Logs (Cuberite)

Connected

Position: 0
Data: {"extra":[{"text":"§6Welcome to the Cuberite test server!"}],"text":""}

Position: 0
Data: {"extra":[{"text":"§6"},{"clickEvent":{"action":"open_url","value":"http://www.cuberite.org/"},"text":"http://www.cuberite.org/"}],"text":""}

Position: 0
Data: {"extra":[{"text":"§6Type /help for all commands"}],"text":""}

1512199499.27 0x23 JoinGamePacket {'entity_id': 45, 'reduced_debug_info': False, 'difficulty': 2, 'game_mode': 0, 'max_players': 100, 'level_type': u'default', 'dimension': 0}

(u'Connected_Player', 0, 0, None)
('list action: ', 0)
1512199499.27 0x2E PlayerListItemPacket

1512199499.27 0x2F PlayerPositionAndLookPacket {'teleport_id': 1, 'yaw': 0.0, 'flags': 0, 'pitch': 0.0, 'y': 62.0, 'x': 0.5, 'z': -15.5}

1512199499.38 0x2F PlayerPositionAndLookPacket {'teleport_id': 2, 'yaw': 0.0, 'flags': 0, 'pitch': 0.0, 'y': 62.0, 'x': 0.5, 'z': -15.5}

('list action: ', 2)
1512199500.27 0x2E PlayerListItemPacket

('list action: ', 2)
1512199501.31 0x2E PlayerListItemPacket

('list action: ', 2)
1512199502.64 0x2E PlayerListItemPacket

('list action: ', 2)
1512199504.38 0x2E PlayerListItemPacket
Position: 0
Data: {"extra":[{"text":"§e[JOIN] §fNew_Player has joined the game"}],"text":""}

(u'New_Player', 0, 0, None)
('list action: ', 0)
1512199505.25 0x2E PlayerListItemPacket

('list action: ', 2)
1512199506.16 0x2E PlayerListItemPacket

('list action: ', 2)
1512199507.07 0x2E PlayerListItemPacket

('list action: ', 2)
1512199507.88 0x2E PlayerListItemPacket

('list action: ', 2)
1512199508.83 0x2E PlayerListItemPacket

('list action: ', 2)
1512199509.57 0x2E PlayerListItemPacket

('list action: ', 2)
1512199510.41 0x2E PlayerListItemPacket

('list action: ', 2)
1512199511.2 0x2E PlayerListItemPacket
^CBye!

New Player

Position: 0
Data: {"extra":[{"text":"§6Welcome to the Cuberite test server!"}],"text":""}

Position: 0
Data: {"extra":[{"text":"§6"},{"clickEvent":{"action":"open_url","value":"http://www.cuberite.org/"},"text":"http://www.cuberite.org/"}],"text":""}

Position: 0
Data: {"extra":[{"text":"§6Type /help for all commands"}],"text":""}

1512199503.83 0x23 JoinGamePacket {'entity_id': 53, 'reduced_debug_info': False, 'difficulty': 2, 'game_mode': 0, 'max_players': 100, 'level_type': u'default', 'dimension': 0}

(u'New_Player', 0, 0, None)
('list action: ', 0)
1512199503.83 0x2E PlayerListItemPacket

(u'Connected_Player', 0, 0, None)
('list action: ', 0)
1512199503.83 0x2E PlayerListItemPacket

1512199503.83 0x2F PlayerPositionAndLookPacket {'teleport_id': 1, 'yaw': 0.0, 'flags': 0, 'pitch': 0.0, 'y': 62.0, 'x': 0.5, 'z': -15.5}

1512199503.89 0x2F PlayerPositionAndLookPacket {'teleport_id': 2, 'yaw': 0.0, 'flags': 0, 'pitch': 0.0, 'y': 62.0, 'x': 0.5, 'z': -15.5}

('list action: ', 2)
1512199504.34 0x2E PlayerListItemPacket

('list action: ', 2)
1512199504.88 0x2E PlayerListItemPacket

('list action: ', 2)
1512199505.33 0x2E PlayerListItemPacket

('list action: ', 2)
1512199505.89 0x2E PlayerListItemPacket

('list action: ', 2)
1512199506.36 0x2E PlayerListItemPacket

('list action: ', 2)
1512199506.94 0x2E PlayerListItemPacket

('list action: ', 2)
1512199507.57 0x2E PlayerListItemPacket
^CBye!

It seems like the behavior is a little off. Cuberite sends two PlayerPositionAndLook packets when a clients connected and sends ping update much more frequently(maybe because c++ is faster?).

Additionally, SpigotMC sends player list update packets when a player joins.

I meant to have the player spawn packets captured as well but am all out of time for tonight.

[mathiascode]

Should be fixed now.

[mathiascode]

World-change issue of invisible players should be fixed, but otherwise this issue still happens.

[tigerw]

One potential issue I see is if two players are joining at the same time, both in limbo waiting to be added to a world, they won't be able to add each other to their own list via BroadcastPlayerListAddPlayer. This doesn't explain why an already connected player doesn't see the right state though.

[tigerw]

I guess this means an already connected player that's doing world travel (i.e. in limbo) won't get updates from any players who connected at that moment, not sure if this is the issue.