NAME

    Action::CircuitBreaker - Module to try to perform an action, with an
    option to suspend execution after a number of failures.

VERSION

    version 0.1

SYNOPSIS

      # Will execute the code, as the circuit will be closed by default.
    
      # OO interface
      use Action::CircuitBreaker;
      Action::CircuitBreaker->new()->run(sub { do_stuff; });

ATTRIBUTES

 error_if_code

      ro, CodeRef

    The code to run to check if the error should count towards the circuit
    breaker. It defaults to:

      # Returns true if there were an exception evaluating to something true
      sub { $_[0] }

    It will be given these arguments:

      * as first argument, a scalar which is the value of any exception
      that were raised by the $attempt_code. Otherwise, undef.

      * as second argument, a HashRef, which contains these keys:

    action_retry

      it's a reference on the ActionRetry instance. That way you can have
      access to the other attributes.

    attempt_result

      It's a scalar, which is the result of $attempt_code. If $attempt_code
      returned a list, then the scalar is the reference on this list.

    attempt_parameters

      It's the reference on the parameters that were given to
      $attempt_code.

    error_if_code return value will be interpreted as a boolean : true
    return value means the execution of $attempt_code was a failure and
    should count towards breaking the ciruit. False means it went well.

    Here is an example of code that gets the arguments properly:

      my $action = Action::CircuitBreaker->new(
        error_if_code => sub {
          my ($error, $h) = @_;
    
          my $attempt_code_result = $h->{attempt_result};
          my $attempt_code_params = $h->{attempt_parameters};
    
          my @results = @$attempt_code_result;
          # will contains (2, 4);
    
          my @original_parameters = @$attempt_code_params;
          # will contains (1, 2);
    
        }
      );
      my @results = $action->run(sub { print @_; }, 1, 2);

 on_failure_code

      ro, CodeRef, optional

    If given, will be executed when an execution fails.

    It will be given the same arguments as error_if_code. See error_if_code
    for their descriptions

 on_circuit_open

      ro, CodeRef, optional

    If given, will be executed the circuit gets opened.

    It will be given the same arguments as error_if_code. See error_if_code
    for their descriptions

 on_circuit_close

      ro, CodeRef, optional

    If given, will be executed the circuit gets closed again.

    It will be given no arguments

 max_retries_number

      ro, int, optional

    Maximum number of retries before opening circuit.

 open_time

      ro, int, optional

    Time in number of seconds to open the circuit for after
    max_retries_number have failed.

METHODS

 run

    Does the following:

    step 1

      Tests the value of _circuit_open_until. If it is positive and the
      current timestamp is before the value, an error is thrown, because
      the circuit is still open. If the value is positive, but before the
      current timestamp, the circuit is closed (by setting
      _circuit_open_until to 0) and optionally, on_circuit_close is run.

    step 2

      If the value of _circuit_open_until is 0, the circuit is closed, and
      the passed sub gets executed. Then it runs the error_if_code CodeRef
      in scalar context, giving it as arguments $error, and the return
      values of $attempt_code. If it returns true, we consider that it was
      a failure, and move to step 3. Otherwise, we consider it means
      success, and return the return values of $attempt_code.

    step 3

      Increase the value of _current_retries_number and check whether it is
      larger than max_retries_number. If it is, then open the circuit by
      setting _circuit_open_until to the current time plus open_time, and
      optionally run on_circuit_open. Then, die with the $error from
      $attempt_code.

    step 4

      Runs the on_failure_code CodeRef in the proper context, giving it as
      arguments $error, and the return values of $attempt_code, and returns
      the results back to the caller.

    Arguments passed to run() will be passed to $attempt_code. They will
    also passed to on_failure_code as well if the case arises.

SEE ALSO

    This code is heavily based on Action::Retry.

AUTHOR

    hangy

COPYRIGHT AND LICENSE

    This software is copyright (c) 2018 by hangy.

    This is free software; you can redistribute it and/or modify it under
    the same terms as the Perl 5 programming language system itself.

