Class: ActiveSupport::BacktraceCleaner
Relationships & Source Files | |
Extension / Inclusion / Inheritance Descendants | |
Subclasses:
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Inherits: | Object |
Defined in: | activesupport/lib/active_support/backtrace_cleaner.rb |
Overview
Backtrace Cleaner
Backtraces often include many lines that are not relevant for the context under review. This makes it hard to find the signal amongst the backtrace noise, and adds debugging time. With a BacktraceCleaner
, filters and silencers are used to remove the noisy lines, so that only the most relevant lines remain.
Filters are used to modify lines of data, while silencers are used to remove lines entirely. The typical filter use case is to remove lengthy path information from the start of each line, and view file paths relevant to the app directory instead of the file system root. The typical silencer use case is to exclude the output of a noisy library from the backtrace, so that you can focus on the rest.
bc = ActiveSupport::BacktraceCleaner.new
root = "#{Rails.root}/"
bc.add_filter { |line| line.delete_prefix(root) } # strip the Rails.root prefix
bc.add_silencer { |line| /puma|rubygems/.match?(line) } # skip any lines from puma or rubygems
bc.clean(exception.backtrace) # perform the cleanup
To reconfigure an existing BacktraceCleaner
(like the default one in Rails) and show as much data as possible, you can always call #remove_silencers!, which will restore the backtrace to a pristine state. If you need to reconfigure an existing BacktraceCleaner
so that it does not filter or modify the paths of any lines of the backtrace, you can call #remove_filters! These two methods will give you a completely untouched backtrace.
Inspired by the Quiet Backtrace gem by thoughtbot.
Constant Summary
-
FORMATTED_GEMS_PATTERN =
# File 'activesupport/lib/active_support/backtrace_cleaner.rb', line 111/\A[^\/]+ \([\w.]+\) /
Class Method Summary
- .new ⇒ BacktraceCleaner constructor
Instance Method Summary
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#add_filter(&block)
Adds a filter from the block provided.
-
#add_silencer(&block)
Adds a silencer from the block provided.
-
#clean(backtrace, kind = :silent)
(also: #filter)
Returns the backtrace after all filters and silencers have been run against it.
-
#clean_frame(frame, kind = :silent)
Returns the frame with all filters applied.
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#filter(backtrace, kind = :silent)
Alias for #clean.
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#remove_filters!
Removes all filters, but leaves in the silencers.
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#remove_silencers!
Removes all silencers, but leaves in the filters.
- #add_core_silencer private
- #add_gem_filter private
- #add_gem_silencer private
- #add_stdlib_silencer private
- #filter_backtrace(backtrace) private
- #initialize_copy(_other) private
- #noise(backtrace) private
- #silence(backtrace) private
Constructor Details
.new ⇒ BacktraceCleaner
# File 'activesupport/lib/active_support/backtrace_cleaner.rb', line 35
def initialize @filters, @silencers = [], [] add_core_silencer add_gem_filter add_gem_silencer add_stdlib_silencer end
Instance Method Details
#add_core_silencer (private)
[ GitHub ]# File 'activesupport/lib/active_support/backtrace_cleaner.rb', line 127
def add_core_silencer add_silencer { |line| line.include?("<internal:") } end
#add_filter(&block)
# File 'activesupport/lib/active_support/backtrace_cleaner.rb', line 83
def add_filter(&block) @filters << block end
#add_gem_filter (private)
[ GitHub ]# File 'activesupport/lib/active_support/backtrace_cleaner.rb', line 118
def add_gem_filter gems_paths = (Gem.path | [Gem.default_dir]).map { |p| Regexp.escape(p) } return if gems_paths.empty? gems_regexp = %r{\A(#{gems_paths.join('|')})/(bundler/)?gems/([^/])-([\w.])/(.*)} gems_result = '\3 (\4) \5' add_filter { |line| line.sub(gems_regexp, gems_result) } end
#add_gem_silencer (private)
[ GitHub ]# File 'activesupport/lib/active_support/backtrace_cleaner.rb', line 131
def add_gem_silencer add_silencer { |line| FORMATTED_GEMS_PATTERN.match?(line) } end
#add_silencer(&block)
Adds a silencer from the block provided. If the silencer returns true
for a given line, it will be excluded from the clean backtrace.
# Will reject all lines that include the word "puma", like "/gems/puma/server.rb" or "/app/my_puma_server/rb"
backtrace_cleaner.add_silencer { |line| /puma/.match?(line) }
# File 'activesupport/lib/active_support/backtrace_cleaner.rb', line 92
def add_silencer(&block) @silencers << block end
#add_stdlib_silencer (private)
[ GitHub ]# File 'activesupport/lib/active_support/backtrace_cleaner.rb', line 135
def add_stdlib_silencer add_silencer { |line| line.start_with?(RbConfig::CONFIG["rubylibdir"]) } end
#clean(backtrace, kind = :silent) Also known as: #filter
Returns the backtrace after all filters and silencers have been run against it. Filters run first, then silencers.
# File 'activesupport/lib/active_support/backtrace_cleaner.rb', line 45
def clean(backtrace, kind = :silent) filtered = filter_backtrace(backtrace) case kind when :silent silence(filtered) when :noise noise(filtered) else filtered end end
#clean_frame(frame, kind = :silent)
Returns the frame with all filters applied. returns nil
if the frame was silenced.
# File 'activesupport/lib/active_support/backtrace_cleaner.rb', line 61
def clean_frame(frame, kind = :silent) frame = frame.to_s @filters.each do |f| frame = f.call(frame.to_s) end case kind when :silent frame unless @silencers.any? { |s| s.call(frame) } when :noise frame if @silencers.any? { |s| s.call(frame) } else frame end end
#filter(backtrace, kind = :silent)
Alias for #clean.
# File 'activesupport/lib/active_support/backtrace_cleaner.rb', line 57
alias :filter :clean
#filter_backtrace(backtrace) (private)
[ GitHub ]# File 'activesupport/lib/active_support/backtrace_cleaner.rb', line 139
def filter_backtrace(backtrace) @filters.each do |f| backtrace = backtrace.map { |line| f.call(line.to_s) } end backtrace end
#initialize_copy(_other) (private)
[ GitHub ]# File 'activesupport/lib/active_support/backtrace_cleaner.rb', line 113
def initialize_copy(_other) @filters = @filters.dup @silencers = @silencers.dup end
#noise(backtrace) (private)
[ GitHub ]# File 'activesupport/lib/active_support/backtrace_cleaner.rb', line 155
def noise(backtrace) backtrace.select do |line| @silencers.any? do |s| s.call(line.to_s) end end end
#remove_filters!
Removes all filters, but leaves in the silencers. Useful if you suddenly need to see entire filepaths in the backtrace that you had already filtered out.
# File 'activesupport/lib/active_support/backtrace_cleaner.rb', line 106
def remove_filters! @filters = [] end
#remove_silencers!
Removes all silencers, but leaves in the filters. Useful if your context of debugging suddenly expands as you suspect a bug in one of the libraries you use.
# File 'activesupport/lib/active_support/backtrace_cleaner.rb', line 99
def remove_silencers! @silencers = [] end
#silence(backtrace) (private)
[ GitHub ]# File 'activesupport/lib/active_support/backtrace_cleaner.rb', line 147
def silence(backtrace) @silencers.each do |s| backtrace = backtrace.reject { |line| s.call(line.to_s) } end backtrace end