class Bosh::Retryable

Public Class Methods

new(options = {}) click to toggle source
# File lib/common/retryable.rb, line 5
def initialize(options = {})
  opts = validate_options(options)

  @ensure_callback = opts[:ensure]
  @matching        = opts[:matching]
  @try_count       = 0
  @retry_exception = nil
  @retry_limit     = opts[:tries]
  @sleeper         = opts[:sleep]

  @matchers = Array(opts[:on]).map do |klass_or_matcher|
    if klass_or_matcher.is_a?(Class)
      ErrorMatcher.by_class(klass_or_matcher)
    else
      klass_or_matcher
    end
  end
end

Public Instance Methods

retryer(&blk) click to toggle source

Loops until the block returns a true value

# File lib/common/retryable.rb, line 25
def retryer(&blk)
  loop do
    @try_count += 1
    y = blk.call(@try_count, @retry_exception)
    @retry_exception = nil # no exception was raised in the block
    return y if y
    raise Bosh::Common::RetryCountExceeded if @try_count >= @retry_limit
    wait
  end
rescue Exception => exception
  raise unless @matchers.any? { |m| m.matches?(exception) }
  raise unless exception.message =~ @matching
  raise if @try_count >= @retry_limit

  @retry_exception = exception
  wait
  retry
ensure
  @ensure_callback.call(@try_count)
end

Private Instance Methods

default_options() click to toggle source
# File lib/common/retryable.rb, line 55
def default_options
  {
    tries: 2,
    sleep: exponential_sleeper,
    on: [],
    matching: /.*/,
    ensure: Proc.new {},
  }
end
exponential_sleeper() click to toggle source
# File lib/common/retryable.rb, line 73
def exponential_sleeper
  lambda { |tries, _| [2**(tries-1), 10].min } # 1, 2, 4, 8, 10, 10..10 seconds
end
sleep(*args, &blk) click to toggle source
# File lib/common/retryable.rb, line 77
def sleep(*args, &blk)
  Kernel.sleep(*args, &blk)
end
validate_options(options) click to toggle source
# File lib/common/retryable.rb, line 48
def validate_options(options)
  merged_options = default_options.merge(options)
  invalid_options = merged_options.keys - default_options.keys
  raise ArgumentError.new("Invalid options: #{invalid_options.join(", ")}") unless invalid_options.empty?
  merged_options
end
wait() click to toggle source
# File lib/common/retryable.rb, line 65
def wait
  sleep(@sleeper.respond_to?(:call) ? @sleeper.call(@try_count, @retry_exception) : @sleeper)
rescue Exception => exception
  raise unless @matchers.any? { |m| m.matches?(exception) }
  # SignalException could be raised while sleeping, so if you want to catch it,
  # it need to be passed in the list of exceptions to ignore
end