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retry.rb
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retry.rb
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module Resque
module Plugins
# If you want your job to retry on failure, simply extend your module/class
# with this module:
#
# class DeliverWebHook
# extend Resque::Plugins::Retry # allows 1 retry by default.
# @queue = :web_hooks
#
# def self.perform(url, hook_id, hmac_key)
# heavy_lifting
# end
# end
#
# Easily do something custom:
#
# class DeliverWebHook
# extend Resque::Plugins::Retry
# @queue = :web_hooks
#
# @retry_limit = 8 # default: 1
# @retry_delay = 60 # default: 0
#
# # used to build redis key, for counting job attempts.
# def self.retry_identifier(url, hook_id, hmac_key)
# "#{url}-#{hook_id}"
# end
#
# def self.perform(url, hook_id, hmac_key)
# heavy_lifting
# end
# end
#
module Retry
# Copy retry criteria checks on inheritance.
def inherited(subclass)
super(subclass)
subclass.instance_variable_set("@retry_criteria_checks", retry_criteria_checks.dup)
end
# @abstract You may override to implement a custom retry identifier,
# you should consider doing this if your job arguments
# are many/long or may not cleanly convert to strings.
#
# Builds a retry identifier using the job arguments. This identifier
# is used as part of the redis key.
#
# @param [Array] args job arguments
# @return [String] job identifier
def retry_identifier(*args)
args_string = args.join('-')
args_string.empty? ? nil : args_string
end
# Builds the redis key to be used for keeping state of the job
# attempts.
#
# @return [String] redis key
def redis_retry_key(*args)
['resque-retry', name, retry_identifier(*args)].compact.join(":").gsub(/\s/, '')
end
# Maximum number of retrys we can attempt to successfully perform the job.
#
# A retry limit of 0 will *never* retry.
# A retry limit of -1 or below will retry forever.
#
# @return [Fixnum]
def retry_limit
@retry_limit ||= 1
end
# Number of retry attempts used to try and perform the job.
#
# The real value is kept in Redis, it is accessed and incremented using
# a before_perform hook.
#
# @return [Fixnum] number of attempts
def retry_attempt
@retry_attempt ||= 0
end
# @abstract
# Number of seconds to delay until the job is retried.
#
# @return [Number] number of seconds to delay
def retry_delay(exception_class = nil)
if @retry_exceptions.is_a?(Hash)
delay = @retry_exceptions[exception_class] || 0
# allow an array of delays.
delay.is_a?(Array) ? delay[retry_attempt] || delay.last : delay
else
@retry_delay ||= 0
end
end
# @abstract
# Number of seconds to sleep after job is requeued
#
# @return [Number] number of seconds to sleep
def sleep_after_requeue
@sleep_after_requeue ||= 0
end
# @abstract
# Modify the arguments used to retry the job. Use this to do something
# other than try the exact same job again.
#
# @return [Array] new job arguments
def args_for_retry(*args)
args
end
# Convenience method to test whether you may retry on a given exception.
#
# @return [Boolean]
def retry_exception?(exception)
return true if retry_exceptions.nil?
!! retry_exceptions.any? { |ex| ex >= exception }
end
# @abstract
# Controls what exceptions may be retried.
#
# Default: `nil` - this will retry all exceptions.
#
# @return [Array, nil]
def retry_exceptions
if @retry_exceptions.is_a?(Hash)
@retry_exceptions.keys
else
@retry_exceptions ||= nil
end
end
# Test if the retry criteria is valid.
#
# @param [Exception] exception
# @param [Array] args job arguments
# @return [Boolean]
def retry_criteria_valid?(exception, *args)
# if the retry limit was reached, dont bother checking anything else.
return false if retry_limit_reached?
# We always want to retry if the exception matches.
should_retry = retry_exception?(exception.class)
# call user retry criteria check blocks.
retry_criteria_checks.each do |criteria_check|
should_retry ||= !!instance_exec(exception, *args, &criteria_check)
end
should_retry
end
# Retry criteria checks.
#
# @return [Array]
def retry_criteria_checks
@retry_criteria_checks ||= []
@retry_criteria_checks
end
# Test if the retry limit has been reached.
#
# @return [Boolean]
def retry_limit_reached?
if retry_limit == 0
true
elsif retry_limit > 0
true if retry_attempt >= retry_limit
else
false
end
end
# Register a retry criteria check callback to be run before retrying
# the job again.
#
# If any callback returns `true`, the job will be retried.
#
# @example Using a custom retry criteria check.
#
# retry_criteria_check do |exception, *args|
# if exception.message =~ /InvalidJobId/
# # don't retry if we got passed a invalid job id.
# false
# else
# true
# end
# end
#
# @yield [exception, *args]
# @yieldparam exception [Exception] the exception that was raised
# @yieldparam args [Array] job arguments
# @yieldreturn [Boolean] false == dont retry, true = can retry
def retry_criteria_check(&block)
retry_criteria_checks << block
end
# Retries the job.
def try_again(exception, *args)
# some plugins define retry_delay and have it take no arguments, so rather than break those,
# we'll just check here to see whether it takes the additional exception class argument or not
temp_retry_delay = ([-1, 1].include?(method(:retry_delay).arity) ? retry_delay(exception.class) : retry_delay)
retry_in_queue = @retry_job_class ? @retry_job_class : self
if temp_retry_delay <= 0
# If the delay is 0, no point passing it through the scheduler
Resque.enqueue(retry_in_queue, *args_for_retry(*args))
else
Resque.enqueue_in(temp_retry_delay, retry_in_queue, *args_for_retry(*args))
end
sleep(sleep_after_requeue) if sleep_after_requeue > 0
clean_retry_key(*args) if @retry_job_class
end
# Resque before_perform hook.
#
# Increments and sets the `@retry_attempt` count.
def before_perform_retry(*args)
retry_key = redis_retry_key(*args)
Resque.redis.setnx(retry_key, -1) # default to -1 if not set.
@retry_attempt = Resque.redis.incr(retry_key) # increment by 1.
end
# Resque after_perform hook.
#
# Deletes retry attempt count from Redis.
def after_perform_retry(*args)
clean_retry_key(*args)
end
# Resque on_failure hook.
#
# Checks if our retry criteria is valid, if it is we try again.
# Otherwise the retry attempt count is deleted from Redis.
def on_failure_retry(exception, *args)
if retry_criteria_valid?(exception, *args)
try_again(exception, *args)
else
clean_retry_key(*args)
end
end
def instance_exec(*args, &block)
mname = "__instance_exec_#{Thread.current.object_id.abs}"
class << self; self end.class_eval{ define_method(mname, &block) }
begin
ret = send(mname, *args)
ensure
class << self; self end.class_eval{ undef_method(mname) } rescue nil
end
ret
end
def clean_retry_key(*args)
Resque.redis.del(redis_retry_key(*args))
end
end
end
end