require 'mongo/types/objectid' require 'mongo/util/ordered_hash' require 'mongo/gridfs/chunk' module XGen module Mongo module GridFS # GridStore is an IO-like object that provides input and output for # streams of data to Mongo. See Mongo's documentation about GridFS for # storage implementation details. # # Example code: # # require 'mongo/gridfs' # GridStore.open(database, 'filename', 'w') { |f| # f.puts "Hello, world!" # } # GridStore.open(database, 'filename, 'r') { |f| # puts f.read # => Hello, world!\n # } # GridStore.open(database, 'filename', 'w+') { |f| # f.puts "But wait, there's more!" # } # GridStore.open(database, 'filename, 'r') { |f| # puts f.read # => Hello, world!\nBut wait, there's more!\n # } class GridStore DEFAULT_ROOT_COLLECTION = 'gridfs' DEFAULT_CONTENT_TYPE = 'text/plain' include Enumerable attr_accessor :filename # Array of strings; may be +nil+ attr_accessor :aliases # Default is DEFAULT_CONTENT_TYPE attr_accessor :content_type attr_accessor :metadata attr_reader :files_id # Time that the file was first saved. attr_reader :upload_date attr_reader :chunk_size attr_accessor :lineno class << self def exist?(db, name, root_collection=DEFAULT_ROOT_COLLECTION) db.collection("#{root_collection}.files").find({'filename' => name}).next_object != nil end def open(db, name, mode, options={}) gs = self.new(db, name, mode, options) result = nil begin result = yield gs if block_given? ensure gs.close end result end def read(db, name, length=nil, offset=nil) GridStore.open(db, name, 'r') { |gs| gs.seek(offset) if offset gs.read(length) } end def readlines(db, name, separator=$/) GridStore.open(db, name, 'r') { |gs| gs.readlines(separator) } end def unlink(db, *names) names.each { |name| gs = GridStore.new(db, name) gs.send(:delete_chunks) gs.collection.remove('_id' => gs.files_id) } end alias_method :delete, :unlink end #--- # ================================================================ #+++ # Mode may only be 'r', 'w', or 'w+'. # # Options. Descriptions start with a list of the modes for which that # option is legitimate. # # :root :: (r, w, w+) Name of root collection to use, instead of # DEFAULT_ROOT_COLLECTION. # # :metadata:: (w, w+) A hash containing any data you want persisted as # this file's metadata. See also metadata= # # :chunk_size :: (w) Sets chunk size for files opened for writing # See also chunk_size= which may only be called before # any data is written. # # :content_type :: (w) Default value is DEFAULT_CONTENT_TYPE. See # also #content_type= def initialize(db, name, mode='r', options={}) @db, @filename, @mode = db, name, mode @root = options[:root] || DEFAULT_ROOT_COLLECTION doc = collection.find({'filename' => @filename}).next_object if doc @files_id = doc['_id'] @content_type = doc['contentType'] @chunk_size = doc['chunkSize'] @upload_date = doc['uploadDate'] @aliases = doc['aliases'] @length = doc['length'] @metadata = doc['metadata'] else @files_id = XGen::Mongo::Driver::ObjectID.new @content_type = DEFAULT_CONTENT_TYPE @chunk_size = Chunk::DEFAULT_CHUNK_SIZE @length = 0 end case mode when 'r' @curr_chunk = nth_chunk(0) @position = 0 when 'w' chunk_collection.create_index("chunk_index", ['files_id', 'n']) delete_chunks @curr_chunk = Chunk.new(self, 'n' => 0) @content_type = options[:content_type] if options[:content_type] @chunk_size = options[:chunk_size] if options[:chunk_size] @metadata = options[:metadata] if options[:metadata] @position = 0 when 'w+' chunk_collection.create_index("chunk_index", ['files_id', 'n']) @curr_chunk = nth_chunk(last_chunk_number) || Chunk.new(self, 'n' => 0) # might be empty @curr_chunk.pos = @curr_chunk.data.length if @curr_chunk @metadata = options[:metadata] if options[:metadata] @position = @length else raise "error: illegal mode #{mode}" end @lineno = 0 @pushback_byte = nil end def collection @db.collection("#{@root}.files") end # Returns collection used for storing chunks. Depends on value of # @root. def chunk_collection @db.collection("#{@root}.chunks") end # Change chunk size. Can only change if the file is opened for write # and no data has yet been written. def chunk_size=(size) unless @mode[0] == ?w && @position == 0 && @upload_date == nil raise "error: can only change chunk size if open for write and no data written." end @chunk_size = size end #--- # ================ reading ================ #+++ def getc if @pushback_byte byte = @pushback_byte @pushback_byte = nil @position += 1 byte elsif eof? nil else if @curr_chunk.eof? @curr_chunk = nth_chunk(@curr_chunk.chunk_number + 1) end @position += 1 @curr_chunk.getc end end def gets(separator=$/) str = '' byte = getc return nil if byte == nil # EOF while byte != nil s = byte.chr str << s break if s == separator byte = getc end @lineno += 1 str end def read(len=nil, buf=nil) buf ||= '' byte = getc while byte != nil && (len == nil || len > 0) buf << byte.chr len -= 1 if len byte = getc if (len == nil || len > 0) end buf end def readchar byte = getc raise EOFError.new if byte == nil byte end def readline(separator=$/) line = gets raise EOFError.new if line == nil line end def readlines(separator=$/) read.split(separator).collect { |line| "#{line}#{separator}" } end def each line = gets while line yield line line = gets end end alias_method :each_line, :each def each_byte byte = getc while byte yield byte byte = getc end end def ungetc(byte) @pushback_byte = byte @position -= 1 end #--- # ================ writing ================ #+++ def putc(byte) if @curr_chunk.pos == @chunk_size prev_chunk_number = @curr_chunk.chunk_number @curr_chunk.save @curr_chunk = Chunk.new(self, 'n' => prev_chunk_number + 1) end @position += 1 @curr_chunk.putc(byte) end def print(*objs) objs = [$_] if objs == nil || objs.empty? objs.each { |obj| str = obj.to_s str.each_byte { |byte| putc(byte) } } nil end def puts(*objs) if objs == nil || objs.empty? putc(10) else print(*objs.collect{ |obj| str = obj.to_s str << "\n" unless str =~ /\n$/ str }) end nil end def <<(obj) write(obj.to_s) end # Writes +string+ as bytes and returns the number of bytes written. def write(string) raise "#@filename not opened for write" unless @mode[0] == ?w count = 0 string.each_byte { |byte| putc byte count += 1 } count end # A no-op. def flush end #--- # ================ status ================ #+++ def eof raise IOError.new("stream not open for reading") unless @mode[0] == ?r @position >= @length end alias_method :eof?, :eof #--- # ================ positioning ================ #+++ def rewind if @curr_chunk.chunk_number != 0 if @mode[0] == ?w delete_chunks @curr_chunk = Chunk.new(self, 'n' => 0) else @curr_chunk == nth_chunk(0) end end @curr_chunk.pos = 0 @lineno = 0 @position = 0 end def seek(pos, whence=IO::SEEK_SET) target_pos = case whence when IO::SEEK_CUR @position + pos when IO::SEEK_END @length - pos when IO::SEEK_SET pos end new_chunk_number = (target_pos / @chunk_size).to_i if new_chunk_number != @curr_chunk.chunk_number @curr_chunk.save if @mode[0] == ?w @curr_chunk = nth_chunk(new_chunk_number) end @position = target_pos @curr_chunk.pos = @position % @chunk_size 0 end def tell @position end #--- # ================ closing ================ #+++ def close if @mode[0] == ?w if @curr_chunk @curr_chunk.truncate @curr_chunk.save if @curr_chunk.pos > 0 end files = collection if @upload_date files.remove('_id' => @files_id) else @upload_date = Time.now end files.insert(to_mongo_object) end @db = nil end def closed? @db == nil end #--- # ================ protected ================ #+++ protected def to_mongo_object h = OrderedHash.new h['_id'] = @files_id h['filename'] = @filename h['contentType'] = @content_type h['length'] = @curr_chunk ? @curr_chunk.chunk_number * @chunk_size + @curr_chunk.pos : 0 h['chunkSize'] = @chunk_size h['uploadDate'] = @upload_date h['aliases'] = @aliases h['metadata'] = @metadata h end def delete_chunks chunk_collection.remove({'files_id' => @files_id}) if @files_id @curr_chunk = nil end def nth_chunk(n) mongo_chunk = chunk_collection.find({'files_id' => @files_id, 'n' => n}).next_object Chunk.new(self, mongo_chunk || {}) end def last_chunk_number (@length / @chunk_size).to_i end end end end end