class Bootsnap::LoadPathCache::Cache

def each_requirable
  @mutex.synchronize do
    @index.each do |rel, entry|
      yield "#{entry}/#{rel}"
    end
  end
end

def find(feature)
  reinitialize if stale?
  feature = feature.to_s
  return feature if feature.start_with?(SLASH)
  return File.expand_path(feature) if feature.start_with?('./')
  @mutex.synchronize do
    x = search_index(feature)
    return x if x
    # The feature wasn't found on our preliminary search through the index.
    # We resolve this differently depending on what the extension was.
    case File.extname(feature)
    # If the extension was one of the ones we explicitly cache (.rb and the
    # native dynamic extension, e.g. .bundle or .so), we know it was a
    # failure and there's nothing more we can do to find the file.
    when *CACHED_EXTENSIONS # .rb, .bundle or .so
      nil
    # If no extension was specified, it's the same situation, since we
    # try appending both cachable extensions in search_index. However,
    # there's a special-case for 'enumerator'. Before ruby 1.9, you had
    # to `require 'enumerator'` to use it. In 1.9+, it's pre-loaded, but
    # doesn't correspond to any entry on the filesystem. Ruby lies. So we
    # lie too, forcing our monkeypatch to return false like ruby would.
    when ""
      raise LoadPathCache::ReturnFalse if feature == 'enumerator' || feature == 'thread'
      nil
    # Ruby allows specifying native extensions as '.so' even when DLEXT
    # is '.bundle'. This is where we handle that case.
    when DOT_SO
      x = search_index(feature[0..-4] + DLEXT)
      return x if x
      if DLEXT2
        search_index(feature[0..-4] + DLEXT2)
      end
    else
      # other, unknown extension. For example, `.rake`. Since we haven't
      # cached these, we legitimately need to run the load path search.
      raise LoadPathCache::FallbackScan
    end
  end
end

def has_dir?(dir)
  reinitialize if stale?
  @mutex.synchronize { @dirs[dir] }
end

def initialize(store, path_obj, development_mode: false)
  @development_mode = development_mode
  @store = store
  @mutex = ::Thread::Mutex.new
  @path_obj = path_obj
  reinitialize
end

def now
  Process.clock_gettime(Process::CLOCK_MONOTONIC).to_i
end

def push_paths(sender, *paths)
  return unless sender == @path_obj
  @mutex.synchronize { push_paths_locked(*paths) }
end

def push_paths_locked(*paths)
  @store.transaction do
    paths.each do |path|
      p = Path.new(path)
      entries, dirs = p.entries_and_dirs(@store)
      # push -> low precedence -> set only if unset
      dirs.each    { |dir| @dirs[dir]  ||= true }
      entries.each { |rel| @index[rel] ||= path }
    end
  end
end

def reinitialize(path_obj = @path_obj)
  @mutex.synchronize do
    @path_obj = path_obj
    ChangeObserver.register(self, @path_obj)
    @index = {}
    @dirs = Hash.new(false)
    @generated_at = now
    push_paths_locked(*@path_obj)
  end
end

def search_index(f)
  try_index(f + DOT_RB) || try_index(f + DLEXT) || try_index(f + DLEXT2) || try_index(f)
end

def search_index(f)
  try_index(f + DOT_RB) || try_index(f + DLEXT) || try_index(f)
end

def stale?
  @development_mode && @generated_at + AGE_THRESHOLD < now
end

def try_index(f)
  if p = @index[f]
    p + '/' + f
  end
end

def unshift_paths(sender, *paths)
  return unless sender == @path_obj
  @mutex.synchronize { unshift_paths_locked(*paths) }
end

def unshift_paths_locked(*paths)
  @store.transaction do
    paths.reverse.each do |path|
      p = Path.new(path)
      entries, dirs = p.entries_and_dirs(@store)
      # unshift -> high precedence -> unconditional set
      dirs.each    { |dir| @dirs[dir]  = true }
      entries.each { |rel| @index[rel] = path }
    end
  end
end