~sircmpwn/aerc

Add distinct keybindings for each compose view
Send emails asyncronously
Implement sending emails /o/
Add :send-message, prepares & writes email to /tmp
Remove leftover debug logging
Handle external message deletions
Handle incoming emails gracefully
Spec out review message screen
Populate "From" header from config for new emails
Add outgoing account configuration
Implement :{next,prev}-field in compose view
Expand compose focus handling a bit
Add initial compose widget
Move aerc to dedicated mailing list
"Press any key to close" for completed processes
Refactor ctx stashing out of exline
Split ex line text handling into dedicated widget
lib/ui: fix UI.Exit race condition

UI.Exit can be accessed from goroutines drawing, goroutines executing
commands and goroutines waiting for events.

    Write at 0x00c0002b2040 by main goroutine:
      main.main.func1()
          /home/simon/src/aerc2/aerc.go:76 +0x33d
      git.sr.ht/~sircmpwn/aerc2/widgets.(*Aerc).BeginExCommand.func1()
          /home/simon/src/aerc2/widgets/aerc.go:245 +0x89
      git.sr.ht/~sircmpwn/aerc2/widgets.(*ExLine).Event()
          /home/simon/src/aerc2/widgets/exline.go:131 +0x442
      git.sr.ht/~sircmpwn/aerc2/widgets.(*Aerc).Event()
          /home/simon/src/aerc2/widgets/aerc.go:116 +0x83c
      git.sr.ht/~sircmpwn/aerc2/widgets.(*Aerc).simulate()
          /home/simon/src/aerc2/widgets/aerc.go:109 +0x12a
      git.sr.ht/~sircmpwn/aerc2/widgets.(*Aerc).Event()
          /home/simon/src/aerc2/widgets/aerc.go:142 +0x722
      git.sr.ht/~sircmpwn/aerc2/lib/ui.(*UI).Tick()
          /home/simon/src/aerc2/lib/ui/ui.go:75 +0x33f
      main.main()
          /home/simon/src/aerc2/aerc.go:94 +0x497

    Previous read at 0x00c0002b2040 by goroutine 19:
      git.sr.ht/~sircmpwn/aerc2/lib/ui.Initialize.func1()
          /home/simon/src/aerc2/lib/ui/ui.go:45 +0x97

    Goroutine 19 (running) created at:
      git.sr.ht/~sircmpwn/aerc2/lib/ui.Initialize()
          /home/simon/src/aerc2/lib/ui/ui.go:44 +0x372
      main.main()
          /home/simon/src/aerc2/aerc.go:87 +0x3a9
lib/ui: fix Grid race condition

This was is more complicated than others. The cells list is accessed by
multiple goroutines:

- Some change the Grid's contents via AddChild/RemoveChild
- Some call Draw
- Some invalidate the grid via Invalidate

Invalidate calls are tricky to handle because they will also invalidate all
child cells. This will inturn trigger the cellInvalidated callback, which needs
to read the list of cells.

For this reason, we use a sync.RWLock which allows multiple concurrent reads.

Below is the race fixed by this commit.

    Read at 0x00c0000bc3d0 by goroutine 7:
      git.sr.ht/~sircmpwn/aerc2/lib/ui.(*Grid).cellInvalidated()
          /home/simon/src/aerc2/lib/ui/grid.go:181 +0x45
      git.sr.ht/~sircmpwn/aerc2/lib/ui.(*Grid).cellInvalidated-fm()
          /home/simon/src/aerc2/lib/ui/grid.go:179 +0x55
      git.sr.ht/~sircmpwn/aerc2/lib/ui.(*Invalidatable).DoInvalidate()
          /home/simon/src/aerc2/lib/ui/invalidatable.go:22 +0x85
      git.sr.ht/~sircmpwn/aerc2/lib/ui.(*Bordered).contentInvalidated-fm()
          /home/simon/src/aerc2/lib/ui/borders.go:39 +0x56
      git.sr.ht/~sircmpwn/aerc2/lib/ui.(*Invalidatable).DoInvalidate()
          /home/simon/src/aerc2/lib/ui/invalidatable.go:22 +0x85
      git.sr.ht/~sircmpwn/aerc2/widgets.NewDirectoryList.func1()
          /home/simon/src/aerc2/widgets/dirlist.go:81 +0x55
      git.sr.ht/~sircmpwn/aerc2/lib/ui.(*Invalidatable).DoInvalidate()
          /home/simon/src/aerc2/lib/ui/invalidatable.go:22 +0x85
      git.sr.ht/~sircmpwn/aerc2/widgets.(*Spinner).Start.func1()
          /home/simon/src/aerc2/widgets/spinner.go:88 +0x82

    Previous write at 0x00c0000bc3d0 by main goroutine:
      [failed to restore the stack]

    Goroutine 7 (running) created at:
      git.sr.ht/~sircmpwn/aerc2/widgets.(*Spinner).Start()
          /home/simon/src/aerc2/widgets/spinner.go:46 +0x98
      git.sr.ht/~sircmpwn/aerc2/widgets.NewDirectoryList()
          /home/simon/src/aerc2/widgets/dirlist.go:37 +0x28b
      git.sr.ht/~sircmpwn/aerc2/widgets.NewAccountView()
          /home/simon/src/aerc2/widgets/account.go:49 +0x5ca
      git.sr.ht/~sircmpwn/aerc2/widgets.NewAerc()
          /home/simon/src/aerc2/widgets/aerc.go:60 +0x807
      main.main()
          /home/simon/src/aerc2/aerc.go:65 +0x33e
lib/msgstore: protect with a mutex

MessageStore has a lot of exported fields that can be read from the outside.
Each read must be protected, because a call from Update could happen at any
time.
widgets/msglist: fix MessageList.store race

This field could be written to in the middle of a Draw call, which reads it
multiple times. Use an atomic variable instead.
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