google-api-ruby-client/lib/google/apis/core/download.rb

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# Copyright 2015 Google Inc.
#
# 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
#
# http://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 'google/apis/core/api_command'
require 'google/apis/errors'
require 'addressable/uri'
module Google
module Apis
module Core
# Streaming/resumable media download support
class DownloadCommand < ApiCommand
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RANGE_HEADER = 'Range'
OK_STATUS = [200, 201, 206]
# File or IO to write content to
# @return [String, File, #write]
attr_accessor :download_dest
# Ensure the download destination is a writable stream.
#
# @return [void]
def prepare!
@state = :start
@download_url = nil
@offset = 0
if download_dest.respond_to?(:write)
@download_io = download_dest
@close_io_on_finish = false
elsif download_dest.is_a?(String)
@download_io = File.open(download_dest, 'wb')
@close_io_on_finish = true
else
@download_io = StringIO.new('', 'wb')
@close_io_on_finish = false
end
super
end
# Close IO stream when command done. Only closes the stream if it was opened by the command.
def release!
@download_io.close if @close_io_on_finish
end
# Execute the upload request once. Overrides the default implementation to handle streaming/chunking
# of file content.
#
# @private
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# @param [HTTPClient] client
# HTTP client
# @yield [result, err] Result or error if block supplied
# @return [Object]
# @raise [Google::Apis::ServerError] An error occurred on the server and the request can be retried
# @raise [Google::Apis::ClientError] The request is invalid and should not be retried without modification
# @raise [Google::Apis::AuthorizationError] Authorization is required
def execute_once(client, &block)
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request_header = header.dup
apply_request_options(request_header)
download_offset = nil
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if @offset > 0
logger.debug { sprintf('Resuming download from offset %d', @offset) }
request_header[RANGE_HEADER] = sprintf('bytes=%d-', @offset)
end
http_res = client.get(url.to_s,
query: query,
header: request_header,
follow_redirect: true) do |res, chunk|
status = res.http_header.status_code.to_i
next unless OK_STATUS.include?(status)
download_offset ||= (status == 206 ? @offset : 0)
download_offset += chunk.bytesize
if download_offset - chunk.bytesize == @offset
next_chunk = chunk
else
# Oh no! Requested a chunk, but received the entire content
chunk_index = @offset - (download_offset - chunk.bytesize)
next_chunk = chunk.byteslice(chunk_index..-1)
next if next_chunk.nil?
end
# logger.debug { sprintf('Writing chunk (%d bytes, %d total)', chunk.length, bytes_read) }
@download_io.write(next_chunk)
@offset += next_chunk.bytesize
end
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@download_io.flush
if @close_io_on_finish
result = nil
else
result = @download_io
end
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check_status(http_res.status.to_i, http_res.header, http_res.body)
success(result, &block)
rescue => e
@download_io.flush
error(e, rethrow: true, &block)
end
end
end
end
end