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e3a1a9dccf
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>
77 lines
1.7 KiB
Ruby
77 lines
1.7 KiB
Ruby
# typed: true
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# frozen_string_literal: true
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require "fcntl"
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# A lock file to prevent multiple Homebrew processes from modifying the same path.
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class LockFile
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attr_reader :path
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sig { params(type: Symbol, locked_path: Pathname).void }
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def initialize(type, locked_path)
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@locked_path = locked_path
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lock_name = locked_path.basename.to_s
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@path = HOMEBREW_LOCKS/"#{lock_name}.#{type}.lock"
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@lockfile = nil
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end
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def lock
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@path.parent.mkpath
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create_lockfile
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return if @lockfile.flock(File::LOCK_EX | File::LOCK_NB)
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raise OperationInProgressError, @locked_path
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end
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def unlock
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return if @lockfile.nil? || @lockfile.closed?
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@lockfile.flock(File::LOCK_UN)
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@lockfile.close
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end
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def with_lock
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lock
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yield
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ensure
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unlock
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end
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private
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def create_lockfile
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return if @lockfile.present? && !@lockfile.closed?
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begin
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@lockfile = @path.open(File::RDWR | File::CREAT)
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rescue Errno::EMFILE
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odie "The maximum number of open files on this system has been reached. Use `ulimit -n` to increase this limit."
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end
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@lockfile.fcntl(Fcntl::F_SETFD, Fcntl::FD_CLOEXEC)
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end
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end
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# A lock file for a formula.
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class FormulaLock < LockFile
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sig { params(rack_name: String).void }
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def initialize(rack_name)
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super(:formula, HOMEBREW_CELLAR/rack_name)
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end
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end
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# A lock file for a cask.
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class CaskLock < LockFile
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sig { params(cask_token: String).void }
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def initialize(cask_token)
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super(:cask, HOMEBREW_PREFIX/"Caskroom/#{cask_token}")
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end
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end
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# A lock file for a download.
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class DownloadLock < LockFile
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sig { params(download_path: Pathname).void }
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def initialize(download_path)
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super(:download, download_path)
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end
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end
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