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# Copyright (C) 2014-2017 MongoDB, 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.
module Mongo
module Grid
class FSBucket
module Stream
# A stream that reads files from the FSBucket.
#
# @since 2.1.0
class Read
include Enumerable
# @return [ FSBucket ] fs The fs bucket from which this stream reads.
#
# @since 2.1.0
attr_reader :fs
# @return [ Hash ] options The stream options.
#
# @since 2.1.0
attr_reader :options
# @return [ BSON::ObjectId, Object ] file_id The id of the file being read.
#
# @since 2.1.0
attr_reader :file_id
# Create a stream for reading files from the FSBucket.
#
# @example Create the stream.
# Stream::Read.new(fs, options)
#
# @param [ FSBucket ] fs The GridFS bucket object.
# @param [ Hash ] options The read stream options.
#
# @since 2.1.0
def initialize(fs, options)
@fs = fs
@options = options.dup
@file_id = @options.delete(:file_id)
@open = true
end
# Iterate through chunk data streamed from the FSBucket.
#
# @example Iterate through the chunk data.
# stream.each do |data|
# buffer << data
# end
#
# @return [ Enumerator ] The enumerator.
#
# @raise [ Error::MissingFileChunk ] If a chunk is found out of sequence.
#
# @yieldparam [ Hash ] Each chunk of file data.
#
# @since 2.1.0
def each
ensure_readable!
num_chunks = (file_info.length + file_info.chunk_size - 1) / file_info.chunk_size
view.each_with_index.reduce(0) do |length_read, (doc, index)|
chunk = Grid::File::Chunk.new(doc)
validate!(index, num_chunks, chunk, length_read)
data = chunk.data.data
yield data
length_read += data.size
end if block_given?
view.to_enum
end
# Read all file data.
#
# @example Read the file data.
# stream.read
#
# @return [ String ] The file data.
#
# @raise [ Error::MissingFileChunk ] If a chunk is found out of sequence.
#
# @since 2.1.0
def read
to_a.join
end
# Close the read stream.
#
# @example Close the stream.
# stream.close
#
# @return [ BSON::ObjectId, Object ] The file id.
#
# @raise [ Error::ClosedStream ] If the stream is already closed.
#
# @since 2.1.0
def close
ensure_open!
view.close_query
@open = false
file_id
end
# Is the stream closed.
#
# @example Is the stream closd.
# stream.closed?
#
# @return [ true, false ] Whether the stream is closed.
#
# @since 2.1.0
def closed?
!@open
end
# Get the read preference used when streaming.
#
# @example Get the read preference.
# stream.read_preference
#
# @return [ Mongo::ServerSelector ] The read preference.
#
# @since 2.1.0
def read_preference
@read_preference ||= options[:read] || fs.read_preference
end
# Get the files collection file information document for the file being read.
#
# @example Get the file info document.
# stream.file_info
#
# @return [ Hash ] The file info document.
#
# @since 2.1.0
def file_info
doc = fs.files_collection.find(_id: file_id).first
if doc
@file_info ||= File::Info.new(Options::Mapper.transform(doc, File::Info::MAPPINGS.invert))
end
end
private
def ensure_open!
raise Error::ClosedStream.new if closed?
end
def ensure_file_info!
raise Error::FileNotFound.new(file_id, :id) unless file_info
end
def ensure_readable!
ensure_open!
ensure_file_info!
end
def view
@view ||= (opts = options.merge(read: read_preference) if read_preference
fs.chunks_collection.find({ :files_id => file_id }, opts || options).sort(:n => 1))
end
def validate!(index, num_chunks, chunk, length_read)
validate_n!(index, chunk)
validate_length!(index, num_chunks, chunk, length_read)
end
def raise_unexpected_chunk_length!(chunk)
close
raise Error::UnexpectedChunkLength.new(file_info.chunk_size, chunk)
end
def validate_length!(index, num_chunks, chunk, length_read)
if num_chunks > 0 && chunk.data.data.size > 0
raise Error::ExtraFileChunk.new unless index < num_chunks
if index == num_chunks - 1
unless chunk.data.data.size + length_read == file_info.length
raise_unexpected_chunk_length!(chunk)
end
elsif chunk.data.data.size != file_info.chunk_size
raise_unexpected_chunk_length!(chunk)
end
end
end
def validate_n!(index, chunk)
unless index == chunk.n
close
raise Error::MissingFileChunk.new(index, chunk)
end
end
end
end
end
end
end
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