Module: HKeyPerfDataReader::RawReader

Includes:

Constants

Defined in:

lib/fluent/plugin/hkey_perf_data_reader.rb

Constant Summary

BUFFER_SIZE =

128kb

128*1024*1024

Constants included from Constants

Constants::ERROR_MORE_DATA, Constants::ERROR_SUCCESS, Constants::HKEY_PERFORMANCE_DATA, Constants::HKEY_PERFORMANCE_TEXT, Constants::PERF_NO_INSTANCES

Class Method Summary

• .read(logger = nil) ⇒ Object
• .read_counter_name_table ⇒ Object

Class Method Details

.read(logger = nil) ⇒ Object

# File 'lib/fluent/plugin/hkey_perf_data_reader.rb', line 336

def self.read(logger = nil)
  # https://docs.microsoft.com/en-us/windows/win32/perfctrs/using-the-registry-functions-to-consume-counter-data
  # https://docs.microsoft.com/en-us/windows/win32/perfctrs/retrieving-counter-data

  hkey = convert_handle(HKEY_PERFORMANCE_DATA)
  type = packdw(0)
  source = make_wstr("Global")
  size = packdw(BUFFER_SIZE)

  # NOTE: By Stoping allocating every time and starting reusing, we might be able to speed up the process.
  data = "\0".force_encoding("ASCII-8BIT") * unpackdw(size)

  begin
    ret = API.RegQueryValueExW(hkey, source, 0, type, data, size)

    while ret == ERROR_MORE_DATA
      size = packdw(unpackdw(size) + BUFFER_SIZE)
      data = "\0".force_encoding("ASCII-8BIT") * unpackdw(size)
      ret = API.RegQueryValueExW(hkey, source, 0, type, data, size)
    end

    unless ret == ERROR_SUCCESS
      raise IOError, "RegQueryValueEx failed with #{ret}."
    end

    return data[0..unpackdw(size)]
  ensure
    ret = API.RegCloseKey(hkey)
    unless ret == ERROR_SUCCESS
      logger&.warn("RegCloseKey failed with #{ret}.")
    end
  end
end

.read_counter_name_table ⇒ Object

# File 'lib/fluent/plugin/hkey_perf_data_reader.rb', line 370

def self.read_counter_name_table
  # This process can be replaced by:
  #  require "win32/registry"
  #  Win32::Registry::HKEY_PERFORMANCE_TEXT.read("Counter")

  # There is a problem with getting some name data in ruby.
  # This is caused by `SetDefaultDllDirectories(LOAD_LIBRARY_SEARCH_DEFAULT_DIRS)` called from `rubygems\defaults\operating_system.rb`.
  # https://github.com/fluent-plugins-nursery/fluent-plugin-windows-exporter/issues/1#issuecomment-994168635

  # https://docs.microsoft.com/en-us/windows/win32/perfctrs/retrieving-counter-names-and-help-text
  hkey = convert_handle(HKEY_PERFORMANCE_TEXT)
  source = make_wstr("Counter")
  size = packdw(0)

  ret = API.RegQueryValueExW(hkey, source, nil, nil, nil, size)

  unless ret == ERROR_SUCCESS
    raise IOError, "RegQueryValueEx failed getting required buffer size. Error is #{ret}."
  end

  data = "\0".force_encoding("ASCII-8BIT") * unpackdw(size)

  ret = API.RegQueryValueExW(hkey, source, nil, nil, data, size)

  unless ret == ERROR_SUCCESS
    raise IOError, "RegQueryValueEx failed with #{ret}."
  end

  # NOTE: no need to call `RegCloseKey` when just taking counter table data

  data
end