bisect-toolchain-snapshot.rb

# $ ruby ./bisect-toolchain-snapshot.rb swift-wasm-DEVELOPMENT-SNAPSHOT-2021-12-12-a swift-wasm-DEVELOPMENT-SNAPSHOT-2022-04-06-a run.sh --workdir /tmp/toolchain-bisect

require "date"
require "net/http"
require "json"
require "tmpdir"

def bisect_date_seq(candidates)
  bad = 0
  good = candidates.length - 1
  loop do
    mid = bad + (good - bad) / 2
    break if mid == good or mid == bad
    puts "select #{candidates[mid]["tag_name"]}, good = #{candidates[good]["tag_name"]}, bad = #{candidates[bad]["tag_name"]}"
    ok = yield candidates[mid]
    if ok
      good = mid
    else
      bad = mid
    end
  end
  candidates[bad]
end

def snapshot_exist?(tag_name, date)
  uri = URI.parse("https://api.github.com/repos/swiftwasm/swift/releases/tags/#{tag_name}")
  p uri
  response = Net::HTTP.get_response(uri)
  if response.code == "200"
    true
  else
    puts "Got #{response}"
    false
  end
end

def fetch_snapshot(tag_name, workdir)
  snapshot_uri = "https://github.com/swiftwasm/swift/releases/download/#{tag_name}/#{tag_name}-ubuntu20.04_x86_64.tar.gz"
  dir = File.join(workdir, tag_name)
  toolchain_dir = File.join(dir, tag_name)
  return toolchain_dir if Dir.exist?(toolchain_dir)
  Dir.mkdir(dir) unless Dir.exist?(dir)

  puts "Fetching #{snapshot_uri} in #{dir} ..."
  Dir.chdir(dir) do
    raise "failed to fetch" unless system("curl -L #{snapshot_uri} | tar xz")
  end
  toolchain_dir
end

def github_get_response(uri)
  headers = {}
  headers["Authorization"] = "token #{ENV["GITHUB_TOKEN"]}" if ENV["GITHUB_TOKEN"]
  http = Net::HTTP.new(uri.host, uri.port)
  http.use_ssl = uri.scheme === "https"
  http.get(uri, headers)
end

def fetch_all_candidates(new, old)
  page = 1
  found_new = false
  found_old = false
  candidates = []
  loop do
    uri = URI.parse("https://api.github.com/repos/swiftwasm/swift/releases?page=#{page}&per_page=30")
    response = github_get_response(uri)

    abort "bad response code #{response.code}" unless response.code == "200"
    releases = JSON.parse(response.body)
    releases.each do |release|
      next unless release["tag_name"].start_with?("swift-wasm-DEVELOPMENT-SNAPSHOT")
      found_new ||= release["tag_name"] == new
      found_old ||= release["tag_name"] == old
      candidates.push(release) if found_new && !found_old
    end
    page += 1
    break if found_new and found_old
  end

  candidates
end

require "optparse"

opts = OptionParser.new
workdir = nil
opts.on("--workdir DIR") { |v| workdir = v }
opts.parse!(ARGV)

workdir ||= Dir.mktmpdir("toolchain-bisect") 

bad_date  = ARGV[0]
good_date = ARGV[1]
cmd = ARGV[2]

unless File.exist?(".cache-candidates.json")
  candidates = fetch_all_candidates(good_date, bad_date)
  File.write(".cache-candidates.json", JSON.dump(candidates))
else
  candidates = JSON.parse(File.read(".cache-candidates.json"))
end

oldest_bad = bisect_date_seq(candidates) do |candidate|
  dir = fetch_snapshot(candidate["tag_name"], workdir)
  new_bin_path = "#{dir}/usr/bin"
  puts "Adding #{new_bin_path}, then testing..." if $VERBOSE
  ok = system({"PATH" => "#{new_bin_path}#{File::PATH_SEPARATOR}#{ENV['PATH']}"}, cmd, chdir: dir)
  puts "#{candidate["tag_name"]} is #{ok ? "good" : "bad"}"
  ok
end

puts "#{oldest_bad["tag_name"]} is the oldest bad snapshot"