45 lines
1.7 KiB
Ruby
45 lines
1.7 KiB
Ruby
# frozen_string_literal: true
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# Monkey patch of Enumerator#next to get better stack traces
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# when an error is raised from within a Fiber.
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# https://bugs.ruby-lang.org/issues/16829
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module EnumeratorNextPatch
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%w(next next_values peek peek_values).each do |name|
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define_method(name) do |*args|
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gitlab_patch_backtrace_marker { super(*args) }
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rescue Exception => err # rubocop: disable Lint/RescueException
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err.set_backtrace(err.backtrace + caller) unless
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has_gitlab_patch_backtrace_marker?(err.backtrace) && backtrace_matches_caller?(err.backtrace)
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raise
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end
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end
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private
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def gitlab_patch_backtrace_marker
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yield
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end
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# This function tells us whether the exception was generated by #next itself or by something in
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# the Fiber that it invokes. If it's generated by #next, then the backtrace will have
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# #gitlab_patch_backtrace_marker as the third item down the trace (since
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# #gitlab_patch_backtrace_marker calls a block, which in turn calls #next.) If it's generated
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# by the Fiber that #next invokes, then it won't contain this marker.
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def has_gitlab_patch_backtrace_marker?(backtrace)
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match = %r(^(.*):[0-9]+:in `gitlab_patch_backtrace_marker'$).match(backtrace[2])
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!!match && match[1] == __FILE__
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end
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# This function makes sure that the rest of the stack trace matches in order to avoid missing
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# an exception that was generated by calling #next on another Enumerator inside the Fiber.
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# This might miss some *very* contrived scenarios involving recursion, but exceptions don't
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# provide Fiber information, so it's the best we can do.
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def backtrace_matches_caller?(backtrace)
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backtrace[3..] == caller[1..]
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end
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end
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Enumerator.prepend(EnumeratorNextPatch)
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