NAME
    Try::Tiny::Retry - Extends Try::Tiny to allow retries

VERSION
    version 0.001

SYNOPSIS
    Use just like Try::Tiny, but with "retry" instead of "try". By default,
    "retry" will try 10 times with exponential backoff:

        use Try::Tiny::Retry;

        retry   { ... }
        catch   { ... }
        finally { ... };

    Or, you can retry only if the error matches some conditions:

        use Try::Tiny::Retry;

        retry     { ... }
        retry_if  { /^could not connect/ }
        catch     { ... };

    Or, you can customize the number of tries and delay timing:

        use Try::Tiny::Retry ':all';

        retry       { ... }
        delay_exp   { 5, 1e6 } # 5 tries, 1 second exponential-backoff
        catch       { ... };

DESCRIPTION
    This module extends Try::Tiny to allow for retrying a block of code
    several times before failing. Otherwise, it works seamlessly like
    Try::Tiny.

    By default, Try::Tiny::Retry exports "retry" and "retry_if", plus "try",
    "catch" and "finally" from Try::Tiny. You can optionally export "delay"
    or "delay_exp". Or you can get everything with the ":all" tag.

FUNCTIONS
  retry
        retry    { ... }  # code that might fail
        retry_if { ... }  # conditions to be met for a retry
        delay    { ... }  # control repeats and intervals between retries
        catch    { ... }; # handler if all retries fail

    The "retry" function works just like "try" from Try::Tiny, except that
    if an exception is thrown, the block may be executed again, depending on
    the "retry_if" and "delay" blocks.

    By default, if no "retry_if" blocks are provided, retries depend only on
    the "delay" block.

    If no "delay" block is provided, the default will be 10 tries with a
    random delay up to 100 milliseconds with an exponential backoff. (See
    "delay_exp".) This has an expected cumulative delay of around 25 seconds
    if all retries fail.

  retry_if
        retry    { ... }
        retry_if { /^could not connect/ }
        catch    { ... };

    A "retry_if" block controls whether a retry should be attempted.

    The block is passed the cumulative number of attempts as an argument.
    The exception caught is provided in $_, just as with "catch". It should
    return a true value if a retry should be attempted.

    Multiple "retry_if" blocks may be provided. Only one needs to evaluate
    to true to enable a retry.

    Using a "retry_if" block based on the retry count is an alternate way to
    allow fewer (but not greater) tries than the default "delay" function,
    but with the default exponential backoff behavior. These are effectively
    equivalent:

        retry     { ... }
        retry_if  { shift() < 3 };

        retry     { ... }
        delay_exp { 3, 1e5 };

  delay
        retry { ... }
        delay {
            return if $_[0] >= 3; # only three tries
            sleep 1;              # constant delay between tries
        }
        catch { ... };

    The "delay" block is executed when the "retry" block throws an exception
    to determine if a retry should be attempted and to manage the delay
    between attempts.

    The block is passed the cumulative number of attempts as an argument. If
    the "delay" block returns an undefined value, no further retries will be
    made and the most recent exception will be rethrown.

    Only one "delay" block is allowed.

  delay_exp
        retry     { ... }
        delay_exp { 3, 10000 } # 3 tries, 10000 µsec
        catch     { ... };

    This function is an exponential-backoff delay-function generator. The
    delay between attempts is randomly selected between 0 and an upper
    bound. The upper bound doubles after each failure.

    It requires a code block as an argument. The block will be evaluated in
    list context and must return two elements. The first element is the
    number of tries allowed. The second element is the starting upper bound
    in microseconds.

    Given number of tries "N" and upper bound "U", the expected cumulative
    delay time if all attempts fail is "0.5 * U * ( 2^(N-1) - 1 )".

SEE ALSO
    There are other retry modules on CPAN, but none of them worked
    seamlessly with Try::Tiny.

    *   Action::Retry — OO (Moo) or functional; various delay strategies;
        supports conditions

    *   AnyEvent::Retry — OO (Moose) and event-driven; various delay
        strategies

    *   Attempt — functional; simple retry count with constant sleep time

    *   Retry — OO (Moose) with fixed exponential backoff; supports
        callbacks on every iteration

    *   Sub::Retry — functional; simple retry count with constant sleep
        time; supports conditions

SUPPORT
  Bugs / Feature Requests
    Please report any bugs or feature requests through the issue tracker at
    <https://github.com/dagolden/Try-Tiny-Retry/issues>. You will be
    notified automatically of any progress on your issue.

  Source Code
    This is open source software. The code repository is available for
    public review and contribution under the terms of the license.

    <https://github.com/dagolden/Try-Tiny-Retry>

      git clone https://github.com/dagolden/Try-Tiny-Retry.git

AUTHOR
    David Golden <dagolden@cpan.org>

COPYRIGHT AND LICENSE
    This software is Copyright (c) 2013 by David Golden.

    This is free software, licensed under:

      The Apache License, Version 2.0, January 2004

