Class: Mongo::Grid::FSBucket::Stream::Read

Relationships & Source Files
Super Chains via Extension / Inclusion / Inheritance
Instance Chain: self, Enumerable
Inherits:	Object
Defined in:	lib/mongo/grid/stream/read.rb

Overview

A stream that reads files from the ::Mongo::Grid::FSBucket.

Since:

2.1.0

Class Method Summary

.new(fs, options) ⇒ Read constructor

Create a stream for reading files from the ::Mongo::Grid::FSBucket.

Instance Attribute Summary

#closed? ⇒ true, false readonly

Is the stream closed.
#file_id ⇒ BSON::ObjectId, Object readonly
#fs ⇒ FSBucket readonly
#options ⇒ Hash readonly

Instance Method Summary

#close ⇒ BSON::ObjectId, Object

Close the read stream.
#each {|Each| ... } ⇒ Enumerator

Iterate through chunk data streamed from the ::Mongo::Grid::FSBucket.
#file_info ⇒ File::Info

Get the files collection file information document for the file being read.
#read ⇒ String

Read all file data.
#read_preference ⇒ BSON::Document

Get the read preference.
#ensure_file_info! private
#ensure_open! private
#ensure_readable! private
#raise_unexpected_chunk_length!(chunk) private
#validate!(index, num_chunks, chunk, length_read) private
#validate_length!(index, num_chunks, chunk, length_read) private
#validate_n!(index, chunk) private
#view private

Constructor Details

.new(fs, options) ⇒ `Read`

Create a stream for reading files from the ::Mongo::Grid::FSBucket.

Examples:

Create the stream.

Stream::Read.new(fs, options)

Parameters:

fs (FSBucket) —

The GridFS bucket object.
options (Hash) —

The read stream options.

Options Hash (options):

:file_info_doc (BSON::Document) —

For internal driver use only. A BSON document to use as file information.

Since:

2.1.0

[ GitHub ]

# File 'lib/mongo/grid/stream/read.rb', line 56


def initialize(fs, options)
  @fs = fs
  @options = options.dup
  @file_id = @options.delete(:file_id)
  @options.freeze
  @open = true
end

Instance Attribute Details

#closed? ⇒ `true`, `false` (readonly)

Is the stream closed.

Examples:

Is the stream closd.

stream.closed?

Returns:

(true, false) —

Whether the stream is closed.

Since:

2.1.0

[ GitHub ]

# File 'lib/mongo/grid/stream/read.rb', line 141


def closed?
  !@open
end

#file_id ⇒ `BSON::ObjectId`, `Object` (readonly)

Returns:

(BSON::ObjectId, Object) —

file_id The id of the file being read.

Since:

2.1.0

[ GitHub ]

# File 'lib/mongo/grid/stream/read.rb', line 42


attr_reader :file_id

#fs ⇒ FSBucket (readonly)

Returns:

(FSBucket) —

fs The fs bucket from which this stream reads.

Since:

2.1.0

[ GitHub ]

# File 'lib/mongo/grid/stream/read.rb', line 32


attr_reader :fs

#options ⇒ `Hash` (readonly)

Returns:

(Hash) —

options The stream options.

Since:

2.1.0

[ GitHub ]

# File 'lib/mongo/grid/stream/read.rb', line 37


attr_reader :options

Instance Method Details

#close ⇒ `BSON::ObjectId`, `Object`

Close the read stream.

If the stream is already closed, this method does nothing.

Examples:

Close the stream.

stream.close

Returns:

(BSON::ObjectId, Object) —

The file id.

Since:

2.1.0

[ GitHub ]

# File 'lib/mongo/grid/stream/read.rb', line 125


def close
  if @open
    view.close_query
    @open = false
  end
  file_id
end

#each {|Each| ... } ⇒ `Enumerator`

Iterate through chunk data streamed from the ::Mongo::Grid::FSBucket.

Examples:

Iterate through the chunk data.

stream.each do |data|
  buffer << data
end

Yield Parameters:

Each (Hash) —

chunk of file data.

Returns:

(Enumerator) —

The enumerator.

Raises:

(Error::MissingFileChunk) —

If a chunk is found out of sequence.

Since:

2.1.0

[ GitHub ]

# File 'lib/mongo/grid/stream/read.rb', line 78


def each
  ensure_readable!
  info = file_info
  num_chunks = (info.length + info.chunk_size - 1) / info.chunk_size
  num_read = 0
  if block_given?
    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
      num_read += 1
      length_read += data.size
    end.tap do
      if num_read < num_chunks
        raise Error::MissingFileChunk.new(num_chunks, num_read)
      end
    end
  else
    view.to_enum
  end
end

#ensure_file_info! (private)

Raises:

(Error::FileNotFound)

Since:

2.1.0

[ GitHub ]

# File 'lib/mongo/grid/stream/read.rb', line 196


def ensure_file_info!
  raise Error::FileNotFound.new(file_id, :id) unless file_info
end

#ensure_open! (private)

Raises:

(Error::ClosedStream)

Since:

2.1.0

[ GitHub ]

# File 'lib/mongo/grid/stream/read.rb', line 192


def ensure_open!
  raise Error::ClosedStream.new if closed?
end

#ensure_readable! (private)

Since:

2.1.0

[ GitHub ]

# File 'lib/mongo/grid/stream/read.rb', line 200


def ensure_readable!
  ensure_open!
  ensure_file_info!
end

#file_info ⇒ File::Info

Note:

The file information is cached in the stream. Subsequent calls to file_info will return the same information that the first call returned, and will not query the database again.

Get the files collection file information document for the file being read.

Returns:

(File::Info) —

The file information object.

Since:

2.1.0

[ GitHub ]

# File 'lib/mongo/grid/stream/read.rb', line 179


def file_info
  @file_info ||= begin
    doc = options[:file_info_doc] || fs.files_collection.find(_id: file_id).first
    if doc
      File::Info.new(Options::Mapper.transform(doc, File::Info::MAPPINGS.invert))
    else
      nil
    end
  end
end

#raise_unexpected_chunk_length!(chunk) (private)

Raises:

(Error::UnexpectedChunkLength)

Since:

2.1.0

[ GitHub ]

# File 'lib/mongo/grid/stream/read.rb', line 222


def raise_unexpected_chunk_length!(chunk)
  close
  raise Error::UnexpectedChunkLength.new(file_info.chunk_size, chunk)
end

#read ⇒ `String`

Read all file data.

Examples:

Read the file data.

stream.read

Returns:

(String) —

The file data.

Raises:

(Error::MissingFileChunk) —

If a chunk is found out of sequence.

Since:

2.1.0

[ GitHub ]

# File 'lib/mongo/grid/stream/read.rb', line 111


def read
  to_a.join
end

#read_preference ⇒ `BSON::Document`

Note:

This method always returns a BSON::Document instance, even though the constructor specifies the type of :read as a Hash, not as a BSON::Document.

Get the read preference.

Returns:

(BSON::Document) —
The read preference. The document may have the following fields:
- :mode – read preference specified as a symbol; valid values are :primary, :primary_preferred, :secondary, :secondary_preferred and :nearest.
- :tag_sets – an array of hashes.
- :local_threshold.

Since:

2.1.0

[ GitHub ]

# File 'lib/mongo/grid/stream/read.rb', line 158


def read_preference
  @read_preference ||= begin
    pref = options[:read] || fs.read_preference
    if BSON::Document === pref
      pref
    else
      BSON::Document.new(pref)
    end
  end
end

#validate!(index, num_chunks, chunk, length_read) (private)

Since:

2.1.0

[ GitHub ]

# File 'lib/mongo/grid/stream/read.rb', line 217


def validate!(index, num_chunks, chunk, length_read)
  validate_n!(index, chunk)
  validate_length!(index, num_chunks, chunk, length_read)
end

#validate_length!(index, num_chunks, chunk, length_read) (private)

Since:

2.1.0

[ GitHub ]

# File 'lib/mongo/grid/stream/read.rb', line 227


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

#validate_n!(index, chunk) (private)

Since:

2.1.0

[ GitHub ]

# File 'lib/mongo/grid/stream/read.rb', line 240


def validate_n!(index, chunk)
  unless index == chunk.n
    close
    raise Error::MissingFileChunk.new(index, chunk)
  end
end

#view (private)

Since:

2.1.0

[ GitHub ]

# File 'lib/mongo/grid/stream/read.rb', line 205


def view
  @view ||= begin
    opts = if read_preference
      options.merge(read: read_preference)
    else
      options
    end

    fs.chunks_collection.find({ :files_id => file_id }, opts).sort(:n => 1)
  end
end

Class: Mongo::Grid::FSBucket::Stream::Read

Overview

Class Method Summary

Instance Attribute Summary

Instance Method Summary

Constructor Details

.new(fs, options) ⇒ Read

Instance Attribute Details

#closed? ⇒ true, false (readonly)

#file_id ⇒ BSON::ObjectId, Object (readonly)

#fs ⇒ FSBucket (readonly)

#options ⇒ Hash (readonly)

Instance Method Details

#close ⇒ BSON::ObjectId, Object

#each {|Each| ... } ⇒ Enumerator

#ensure_file_info! (private)

#ensure_open! (private)

#ensure_readable! (private)

#file_info ⇒ File::Info

#raise_unexpected_chunk_length!(chunk) (private)

#read ⇒ String

#read_preference ⇒ BSON::Document

#validate!(index, num_chunks, chunk, length_read) (private)

#validate_length!(index, num_chunks, chunk, length_read) (private)

#validate_n!(index, chunk) (private)

#view (private)

.new(fs, options) ⇒ `Read`

#closed? ⇒ `true`, `false` (readonly)

#file_id ⇒ `BSON::ObjectId`, `Object` (readonly)

#options ⇒ `Hash` (readonly)

#close ⇒ `BSON::ObjectId`, `Object`

#each {|Each| ... } ⇒ `Enumerator`

#read ⇒ `String`

#read_preference ⇒ `BSON::Document`