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# Copyright 2025 Google LLC
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
# https://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.
require "gapic/common/retry_policy"
module Gapic
module Common
##
# Provides a generic mechanism for periodic polling an operation.
#
# Polling intervals are calculated from the provided retry policy.
#
# Supports exponential backoff via `multiplier`, and automatically
# retries gRPC errors listed in `retry_codes`.
#
class PollingHarness
# @return [Gapic::Common::RetryPolicy] The retry policy associated with this instance.
attr_reader :retry_policy
##
# Create new Gapic::Common::PollingHarness instance.
#
# @param retry_policy [Gapic::Common::RetryPolicy] The retry policy to
# use. If not provided, a new retry policy is constructed from the
# given kwargs.
# @param kwargs [keywords] Keyword arguments used to create a new retry
# policy. See {RetryPolicy#initialize}.
#
def initialize retry_policy: nil, **kwargs
@retry_policy = retry_policy ? retry_policy.dup : RetryPolicy.new(**kwargs)
end
##
# Perform polling with exponential backoff. Repeatedly calls the given
# block until it returns a result other than the given sentinel value
# (normally `nil`), then returns that final result.
#
# Uses the retry policy regulate retries, including delays between tries,
# retriable errors, and final timeout. If an error code other than those
# listed in {RetryPolicy#retry_codes} is raised, it is propagated out. If
# the timeout expires, the given timeout result (normally `nil`) is
# returned.
#
# @param wait_sentinel [Object] The return value that should signal the
# polling harness to continue waiting. Any other value is treated as
# a real result and returned. Defaults to `nil`.
# @param timeout_result [Object] The result to return if timeout occurs.
# Defaults to `nil`.
#
# @yieldreturn [Object] The result of the polling logic, either a result
# to return, or the `wait_sentinel` value.
#
def wait wait_sentinel: nil, timeout_result: nil, mock_delay: false
unless block_given?
raise ArgumentError, "No callback provided to wait method."
end
retry_policy.start! mock_delay: mock_delay
loop do
begin
response = yield
return response unless response == wait_sentinel
rescue StandardError => e # Currently retry_error only accounts for ::GRPC::BadStatus.
raise unless retry_policy.retry_error? e
end
retry_policy.perform_delay!
return timeout_result unless retry_policy.retry_with_deadline?
end
end
end
end
end
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