f46b678acf qt: lock cs_main, m_cached_tip_mutex in that order (Vasil Dimov)
Pull request description:
Always lock the mutexes `cs_main` and `m_cached_tip_mutex` in
the same order: `cs_main`, `m_cached_tip_mutex`. Otherwise we may end up
in a deadlock.
`ClientModel::m_cached_tip_blocks` is protected by
`ClientModel::m_cached_tip_mutex`. There are two access paths that
lock the two mutexes in opposite order:
```
validation.cpp:2868 CChainState::ActivateBestChain(): lock cs_main
validation.cpp:2916 CChainState::ActivateBestChain(): call uiInterface.NotifyBlockTip()
ui_interface.cpp:52 CClientUIInterface::NotifyBlockTip(): go deep in boost
...
qt/clientmodel.cpp:255 BlockTipChanged(): lock m_cached_tip_mutex
```
and
```
qt/clientmodel.cpp:119 ClientModel::getBestBlockHash(): lock m_cached_tip_mutex
qt/clientmodel.cpp:121 ClientModel::getBestBlockHash(): call m_node.getBestBlockHash()
interfaces/node.cpp:200 NodeImpl::getBestBlockHash(): lock cs_main
```
From `debug.log`:
```
POTENTIAL DEADLOCK DETECTED
Previous lock order was:
m_cs_chainstate validation.cpp:2851
(1) cs_main validation.cpp:2868
::mempool.cs validation.cpp:2868
(2) clientmodel->m_cached_tip_mutex qt/clientmodel.cpp:255
Current lock order is:
(2) m_cached_tip_mutex qt/clientmodel.cpp:119
(1) ::cs_main interfaces/node.cpp:200
```
The possible deadlock was introduced in #17993
ACKs for top commit:
jonasschnelli:
Tested ACK f46b678acf
Tree-SHA512: 904f24b39bdc97c4d0ecb897a6980d8d479814535eb167e23105238800ea2f1f85273e3370cf894db58bc597f94c4f2e81fb68d0ff3362d468c16af5ce8f5d78
Contains Designer UI files. They are created with Qt Creator, but can be edited using any text editor.
locale
Contains translations. They are periodically updated. The process is described here.
res
Resources such as the icon.
test
Tests.
bitcoingui.(h/cpp)
Represents the main window of the Bitcoin UI.
*model.(h/cpp)
The model. When it has a corresponding controller, it generally inherits from QAbstractTableModel. Models that are used by controllers as helpers inherit from other Qt classes like QValidator.
ClientModel is used by the main application bitcoingui and several models like peertablemodel.
*page.(h/cpp)
A controller. :NAMEpage.cpp generally includes :NAMEmodel.h and forms/:NAME.page.ui with a similar :NAME.
*dialog.(h/cpp)
Various dialogs, e.g. to open a URL. Inherit from QDialog.
paymentserver.(h/cpp)
Used to process BIP21 payment URI requests. Also handles URI based application switching (e.g. when following a bitcoin:... link from a browser).
walletview.(h/cpp)
Represents the view to a single wallet.
Other .h/cpp files
UI elements like BitcoinAmountField, which inherit from QWidget.
bitcoinstrings.cpp: automatically generated
bitcoinunits.(h/cpp): BTC / mBTC / etc handling
callback.h
guiconstants.h: UI colors, app name, etc
guiutil.h: several helper functions
macdockiconhandler.(h/mm): macOS dock icon handler
macnotificationhandler.(h/mm): display notifications in macOS
Contribute
See CONTRIBUTING.md for general guidelines. Specifically for Qt:
don't change local/bitcoin_en.ts; this happens automatically
Using Qt Creator as IDE
You can use Qt Creator as an IDE. This is especially useful if you want to change
the UI layout.
Download and install the community edition of Qt Creator.
Uncheck everything except Qt Creator during the installation process.
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