My experience recently playing around with our locking behaviour is
that, while mostly seamless and not seen by users, it's leaks
implementation details a bit too heavily.
As a result, the following improvements are in this commit:
- Ensure that, whenever possible, we tell the user the actual command
that is holding a given lock instead of the lock name (an internal
implementation detail)
- Make the locking error output a little more consistent and user
friendly
- Add a `DownloadLock` class to simplify locking downloads
- Add a `HOMEBREW_LOCK_CONTEXT` variable to allow adding additional
context for logging error messages
- Lock paths and leave deciding how this translates to lock names up
to the locking code itself
- Lock the Cellar/Caskroom paths explicitly rather than implicitly
Co-authored-by: Carlo Cabrera <30379873+carlocab@users.noreply.github.com>
We're seeing type errors when building formulae that use something
like `xcodebuild ..., "-arch", Hardware::CPU.arch`, since `CPU.arch`
is a symbol. We've been addressing these issues by calling `#to_s` on
the value but there was some talk about simply expanding the type
signatures to accommodate anything that will be cast to a `String`.
There's maybe still an argument to be made for doing string conversion
in formulae but expanding the type signatures will resolve a number of
existing type errors if we simply want to rely on implicit type
casting.
Past that, this also updates the type signature for `BuildError` to
align with the `#system` signature changes, as we receive a type error
otherwise.
- For some of these I changed `context` to `describe` as it fit better
rather than contriving a "when", "with" or "without", or massively
restructuring the tests.
The refactor in 6e8f5d0958247e4b4d629866099ed2836a0e0863 means that the
exception no longer exposes the name of the package with multiple versions,
and as a result the rescuer is unable to print this information.
Because we now have a path in which MultipleVersionsInstalledError doesn't
have the name at all, we can't reasonably restore the old behaviour.
And since rack resolution happens purely internal to the function that
raises the exception, the caller has no way to know what name to use.
However, since the exception text gets printed anyway, we can just move
this text into the exception itself.
Fixes the following error:
```
Error: mpd has multiple installed versions
Error: undefined method `name' for #<MultipleVersionsInstalledError:0x00007fc6009d8870>
/usr/local/Homebrew/Library/Homebrew/cmd/uninstall.rb:137:in `rescue in uninstall'
/usr/local/Homebrew/Library/Homebrew/cmd/uninstall.rb:135:in `uninstall'
/usr/local/Homebrew/Library/Homebrew/brew.rb:119:in `<main>'
```
