Class: Moped::GridFS::File

Inherits:
Object
  • Object
show all
Includes:
AccessModes, Bucketable, Inspectable
Defined in:
lib/moped/gridfs/file.rb

Constant Summary collapse

EMPTINESS = 
''.force_encoding('BINARY')
DEFAULT_CHUNK_SIZE = 
255 * 1024

Constants included from AccessModes

AccessModes::ACCESS_MODES

Instance Attribute Summary collapse

Instance Method Summary collapse

Methods included from AccessModes

#append?, #read_only?, #read_write?, #readable?, #writable?, #write_only?

Methods included from Bucketable

#chunks_collection, #files_collection

Constructor Details

#initialize(bucket, mode, selector) ⇒ File

Returns a new instance of File.

Raises:

  • (ArgumentError) 


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# File 'lib/moped/gridfs/file.rb', line 14

def initialize(bucket, mode, selector)
  selector = parse_selector(selector)
  @mode = mode
  @bucket = bucket
  @cached_chunk = nil
  @pos = 0

  raise ArgumentError.new("Invalid access mode #{mode}") unless ACCESS_MODES.include?(mode)

  document = files_collection.find(selector).first

  raise "No such file" if need_file? and !document

  if document and truncate?
    chunks_collection.find(files_id: document['_id']).remove_all
    files_collection.find(_id: document['_id']).remove_all

    @attributes = normalize_attributes(selector)
  else
    @attributes = normalize_attributes(document || selector)
    @attributes.freeze if read_only?
  end

  define_dynamic_accessors

  file_query.upsert(attributes) if writable?

  @pos = length if append_only?
end

Instance Attribute Details

#attributes ⇒ Object (readonly)

Returns the value of attribute attributes.



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# File 'lib/moped/gridfs/file.rb', line 12

def attributes
  @attributes
end

#bucket ⇒ Object (readonly)

Returns the value of attribute bucket.



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# File 'lib/moped/gridfs/file.rb', line 12

def bucket
  @bucket
end

#mode ⇒ Object (readonly)

Returns the value of attribute mode.



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# File 'lib/moped/gridfs/file.rb', line 12

def mode
  @mode
end

#pos ⇒ Object Also known as: tell

Returns the value of attribute pos.



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# File 'lib/moped/gridfs/file.rb', line 12

def pos
  @pos
end

Instance Method Details

#default_chunk_size ⇒ Object 



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# File 'lib/moped/gridfs/file.rb', line 139

def default_chunk_size
  DEFAULT_CHUNK_SIZE
end

#eof? ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/moped/gridfs/file.rb', line 58

def eof?
  raise "Not opened for reading" if write_only?

  pos >= length
end

#inspect ⇒ Object 



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# File 'lib/moped/gridfs/file.rb', line 143

def inspect
  build_inspect_string(bucket: bucket.name, _id: _id, mode: mode, filename: filename, length: length)
end

#read(size = length) ⇒ Object 



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# File 'lib/moped/gridfs/file.rb', line 66

def read(size = length)
  raise "Not opened for reading" if write_only?

  check_negative_value(size)

  chunk_number = pos / chunk_size
  chunk_offset = pos % chunk_size

  data = EMPTINESS

  loop do
    break if data.size >= size
    break unless read_chunk(chunk_number)
    buffer = @cached_chunk[:data][chunk_offset..-1]
    data.empty? ? (data = buffer) : (data << buffer)
    chunk_number += 1
    chunk_offset = 0
  end

  data = data[0..size - 1]
  @pos += data.size
  data
end

#rewind ⇒ Object 



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# File 'lib/moped/gridfs/file.rb', line 54

def rewind
  self.pos = 0
end

#write(data) ⇒ Object 



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# File 'lib/moped/gridfs/file.rb', line 90

def write(data)
  raise "Not opened for writing" if read_only?

  data.force_encoding('BINARY') if data.respond_to?(:force_encoding)

  @pos = length if @pos > length
  @pos = length if append?

  chunk_number = pos / chunk_size
  chunk_offset = pos % chunk_size
  written = data.size
  new_length = 0

  loop do
    if buffer = read_chunk(chunk_number)
      data = (chunk_offset.zero? ? EMPTINESS : buffer[0..chunk_offset - 1]) + data + (buffer[chunk_offset + data.size..-1] || EMPTINESS)
    end

    to_write = data[0..chunk_size - 1] || EMPTINESS

    break if to_write.empty?

    new_length = chunk_number * chunk_size + write_chunk(chunk_number, to_write)

    data = data[chunk_size..-1] || EMPTINESS

    break if data.empty?

    chunk_number += 1
    chunk_offset = 0
  end

  # Update internal position
  @pos += written

  # Calculate new md5 (if needed)
  md5 = bucket.md5(@attributes[:_id]) if written > 0

  # Update if something changed
  updates = {}
  updates[:md5] = md5 if md5
  updates[:length] = new_length if new_length > length
  change_attributes(updates) if updates.any?

  written
end