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Allowing to perform analysis of references to an object.
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,149 @@ | ||
| require 'json' | ||
| require 'readline' | ||
| require 'set' | ||
|
|
||
| module Heapy | ||
|
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||
| # Follows references to given object addresses and prints | ||
| # them as a reference stack. | ||
| # Since multiple reference stacks are possible, it will preferably | ||
| # try to print a stack that leads to a root node, since reference chains | ||
| # leading to a root node will make an object non-collectible by GC. | ||
| # | ||
| # In case no chain to a root node can be found one possible stack is printed | ||
| # as a fallback. | ||
| class ReferenceExplorer | ||
| def initialize(filename) | ||
| @objects = {} | ||
| @reverse_references = {} | ||
| @virtual_root_address = 0 | ||
| File.open(filename) do |f| | ||
| f.each.with_index do |line, i| | ||
| o = JSON.parse(line) | ||
| addr = add_object(o) | ||
| add_reverse_references(o, addr) | ||
| end | ||
| end | ||
| end | ||
|
|
||
| def drill_down_list(addresses) | ||
| addresses.each { |addr| drill_down(addr) } | ||
| end | ||
|
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||
| def drill_down_interactive | ||
| while buf = Readline.readline("Enter address > ", true) | ||
| drill_down(buf) | ||
| end | ||
| end | ||
|
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||
| def drill_down(addr_string) | ||
| addr = addr_string.to_i(16) | ||
| puts | ||
|
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||
| chain = find_root_chain(addr) | ||
| unless chain | ||
| puts 'Could not find a reference chain leading to a root node. Searching for a non-specific chain now.' | ||
| puts | ||
| chain = find_any_chain(addr) | ||
| end | ||
|
|
||
| puts '## Reference chain' | ||
| chain.each do |ref| | ||
| puts format_object(ref) | ||
| end | ||
|
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||
| puts | ||
| puts "## All references to #{addr_string}" | ||
| refs = @reverse_references[addr] || [] | ||
| refs.each do |ref| | ||
| puts " * #{format_object(ref)}" | ||
| end | ||
|
|
||
| puts | ||
| end | ||
|
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| def inspect | ||
| "<ReferenceExplorer #{@objects.size} objects; #{@reverse_references.size} back-refs>" | ||
| end | ||
|
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||
| private | ||
|
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| def add_object(o) | ||
| addr = o['address']&.to_i(16) | ||
| if !addr && o['type'] == 'ROOT' | ||
| addr = @virtual_root_address | ||
| o['name'] ||= o['root'] | ||
| @virtual_root_address += 1 | ||
| end | ||
|
|
||
| return unless addr | ||
|
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||
| simple_object = o.slice('type', 'file', 'name', 'class', 'length', 'imemo_type') | ||
| simple_object['class'] = simple_object['class'].to_i(16) if simple_object.key?('class') | ||
| simple_object['file'] = o['file'] + ":#{o['line']}" if o.key?('file') && o.key?('line') | ||
|
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| @objects[addr] = simple_object | ||
|
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| addr | ||
| end | ||
|
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||
| def add_reverse_references(o, addr) | ||
| return unless o.key?('references') | ||
| o.fetch('references').map { |r| r.to_i(16) }.each do |ref| | ||
| (@reverse_references[ref] ||= []) << addr | ||
| end | ||
| end | ||
|
|
||
| def find_root_chain(addr, known_addresses = Set.new) | ||
| known_addresses << addr | ||
|
|
||
| return [addr] if addr < @virtual_root_address # assumption: only root objects have smallest possible addresses | ||
|
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||
| references = @reverse_references[addr] || [] | ||
|
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| references.reject { |a| known_addresses.include?(a) }.each do |ref| | ||
| path = find_root_chain(ref, known_addresses) | ||
| return [addr] + path if path | ||
| end | ||
|
|
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| nil | ||
| end | ||
|
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| def find_any_chain(addr, known_addresses = Set.new) | ||
| known_addresses << addr | ||
|
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| references = @reverse_references[addr] || [] | ||
|
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| next_ref = references.reject { |a| known_addresses.include?(a) }.first | ||
| if next_ref | ||
| [addr] + find_any_chain(next_ref, known_addresses) | ||
| else | ||
| [] | ||
| end | ||
| end | ||
|
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||
| def format_path(path) | ||
| return '' unless path | ||
|
|
||
| path.split('/').reverse.take(4).reverse.join('/') | ||
| end | ||
|
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||
| def format_object(addr) | ||
| obj = @objects[addr] | ||
| return "<Unknown 0x#{addr.to_s(16)}>" unless obj | ||
|
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||
| desc = if obj['name'] | ||
| obj['name'] | ||
| elsif obj['type'] == 'OBJECT' | ||
| @objects.dig(obj['class'], 'name') | ||
| elsif obj['type'] == 'ARRAY' | ||
| "#{obj['length']} items" | ||
| elsif obj['type'] == 'IMEMO' | ||
| obj['imemo_type'] | ||
| end | ||
| desc = desc ? " #{desc}" : '' | ||
| addr = addr ? " 0x#{addr.to_s(16).upcase}" : '' | ||
| "<#{obj['type']}#{desc}#{addr}> (allocated at #{format_path obj['file']})" | ||
| end | ||
| end | ||
| end |