104 lines
3.7 KiB
Ruby
104 lines
3.7 KiB
Ruby
module ActiveSupport
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# Backtraces often include many lines that are not relevant for the context
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# under review. This makes it hard to find the signal amongst the backtrace
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# noise, and adds debugging time. With a BacktraceCleaner, filters and
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# silencers are used to remove the noisy lines, so that only the most relevant
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# lines remain.
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#
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# Filters are used to modify lines of data, while silencers are used to remove
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# lines entirely. The typical filter use case is to remove lengthy path
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# information from the start of each line, and view file paths relevant to the
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# app directory instead of the file system root. The typical silencer use case
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# is to exclude the output of a noisy library from the backtrace, so that you
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# can focus on the rest.
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#
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# bc = BacktraceCleaner.new
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# bc.add_filter { |line| line.gsub(Rails.root.to_s, '') } # strip the Rails.root prefix
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# bc.add_silencer { |line| line =~ /mongrel|rubygems/ } # skip any lines from mongrel or rubygems
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# bc.clean(exception.backtrace) # perform the cleanup
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#
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# To reconfigure an existing BacktraceCleaner (like the default one in Rails)
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# and show as much data as possible, you can always call
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# <tt>BacktraceCleaner#remove_silencers!</tt>, which will restore the
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# backtrace to a pristine state. If you need to reconfigure an existing
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# BacktraceCleaner so that it does not filter or modify the paths of any lines
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# of the backtrace, you can call <tt>BacktraceCleaner#remove_filters!</tt>
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# These two methods will give you a completely untouched backtrace.
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#
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# Inspired by the Quiet Backtrace gem by Thoughtbot.
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class BacktraceCleaner
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def initialize
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@filters, @silencers = [], []
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end
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# Returns the backtrace after all filters and silencers have been run
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# against it. Filters run first, then silencers.
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def clean(backtrace, kind = :silent)
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filtered = filter_backtrace(backtrace)
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case kind
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when :silent
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silence(filtered)
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when :noise
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noise(filtered)
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else
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filtered
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end
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end
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alias :filter :clean
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# Adds a filter from the block provided. Each line in the backtrace will be
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# mapped against this filter.
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#
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# # Will turn "/my/rails/root/app/models/person.rb" into "/app/models/person.rb"
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# backtrace_cleaner.add_filter { |line| line.gsub(Rails.root, '') }
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def add_filter(&block)
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@filters << block
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end
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# Adds a silencer from the block provided. If the silencer returns +true+
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# for a given line, it will be excluded from the clean backtrace.
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#
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# # Will reject all lines that include the word "mongrel", like "/gems/mongrel/server.rb" or "/app/my_mongrel_server/rb"
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# backtrace_cleaner.add_silencer { |line| line =~ /mongrel/ }
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def add_silencer(&block)
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@silencers << block
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end
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# Removes all silencers, but leaves in the filters. Useful if your
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# context of debugging suddenly expands as you suspect a bug in one of
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# the libraries you use.
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def remove_silencers!
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@silencers = []
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end
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# Removes all filters, but leaves in the silencers. Useful if you suddenly
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# need to see entire filepaths in the backtrace that you had already
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# filtered out.
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def remove_filters!
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@filters = []
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end
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private
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def filter_backtrace(backtrace)
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@filters.each do |f|
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backtrace = backtrace.map { |line| f.call(line) }
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end
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backtrace
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end
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def silence(backtrace)
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@silencers.each do |s|
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backtrace = backtrace.reject { |line| s.call(line) }
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end
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backtrace
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end
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def noise(backtrace)
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backtrace - silence(backtrace)
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end
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end
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end
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