552 lines
15 KiB
Ruby
552 lines
15 KiB
Ruby
# --
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# Copyright (C) 2008-2009 10gen Inc.
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#
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# Licensed under the Apache License, Version 2.0 (the "License");
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# you may not use this file except in compliance with the License.
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# You may obtain a copy of the License at
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#
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# http://www.apache.org/licenses/LICENSE-2.0
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#
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# Unless required by applicable law or agreed to in writing, software
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# distributed under the License is distributed on an "AS IS" BASIS,
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# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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# See the License for the specific language governing permissions and
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# limitations under the License.
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# ++
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require 'mongo/types/objectid'
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require 'mongo/util/ordered_hash'
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require 'mongo/gridfs/chunk'
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module GridFS
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# GridStore is an IO-like class that provides input and output for
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# streams of data to MongoDB.
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#
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# @example
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#
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# include GridFS
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#
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# #Store the text "Hello, world!" in the grid store.
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# GridStore.open(database, 'filename', 'w') do |f|
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# f.puts "Hello, world!"
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# end
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#
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# # Output "Hello, world!"
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# GridStore.open(database, 'filename', 'r') do |f|
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# puts f.read
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# end
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#
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# # Add text to the grid store.
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# GridStore.open(database, 'filename', 'w+') do |f|
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# f.puts "But wait, there's more!"
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# end
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#
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# # Retrieve everything, outputting "Hello, world!\nBut wait, there's more!\n"
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# GridStore.open(database, 'filename', 'r') do |f|
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# puts f.read
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# end
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class GridStore
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DEFAULT_ROOT_COLLECTION = 'fs'
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DEFAULT_CONTENT_TYPE = 'text/plain'
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include Enumerable
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attr_accessor :filename
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# Array of strings; may be +nil+
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attr_accessor :aliases
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# Default is DEFAULT_CONTENT_TYPE
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attr_accessor :content_type
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# Size of file in bytes
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attr_reader :length
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attr_accessor :metadata
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attr_reader :files_id
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# Time that the file was first saved.
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attr_reader :upload_date
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attr_reader :chunk_size
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attr_accessor :lineno
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attr_reader :md5
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# Determine whether a given file exists in the GridStore.
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#
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# @param [Mongo::DB] a MongoDB database.
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# @param [String] name the filename.
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# @param [String] root_collection the name of the gridfs root collection.
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#
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# @return [Boolean]
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def self.exist?(db, name, root_collection=DEFAULT_ROOT_COLLECTION)
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db.collection("#{root_collection}.files").find({'filename' => name}).next_document != nil
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end
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# Open a GridFS file for reading, writing, or appending. Note that
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# this method must be used with a block.
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#
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# @param [Mongo::DB] a MongoDB database.
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# @param [String] name the filename.
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# @param [String] mode one of 'r', 'w', or 'w+' for reading, writing,
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# and appending, respectively.
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# @param [Hash] options any of the options available on
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# GridStore initialization.
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#
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# @see GridStore#initialize.
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# @see The various GridStore class methods, e.g., GridStore.open, GridStore.read etc.
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def self.open(db, name, mode, options={})
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gs = self.new(db, name, mode, options)
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result = nil
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begin
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result = yield gs if block_given?
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ensure
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gs.close
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end
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result
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end
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# Read a file stored in GridFS.
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#
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# @param [Mongo::DB] db a MongoDB database.
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# @param [String] name the name of the file.
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# @param [Integer] length the number of bytes to read.
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# @param [Integer] offset the number of bytes beyond the
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# beginning of the file to start reading.
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#
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# @return [String] the file data
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def self.read(db, name, length=nil, offset=nil)
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GridStore.open(db, name, 'r') do |gs|
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gs.seek(offset) if offset
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gs.read(length)
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end
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end
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# List the contents of all GridFS files stored in the given db and
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# root collection.
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#
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# @param [Mongo::DB] db a MongoDB database.
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# @param [String] root_collection the name of the root collection.
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#
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# @return [Array]
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def self.list(db, root_collection=DEFAULT_ROOT_COLLECTION)
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db.collection("#{root_collection}.files").find().map do |f|
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f['filename']
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end
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end
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# Get each line of data from the specified file
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# as an array of strings.
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#
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# @param [Mongo::DB] db a MongoDB database.
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# @param [String] name the filename.
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# @param [String, Reg] separator
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#
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# @return [Array]
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def self.readlines(db, name, separator=$/)
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GridStore.open(db, name, 'r') do |gs|
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gs.readlines(separator)
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end
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end
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# Remove one for more files from the given db.
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#
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# @param [Mongo::Database] db a MongoDB database.
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# @param [Array<String>] names the filenames to remove
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#
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# @return [True]
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def self.unlink(db, *names)
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names.each do |name|
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gs = GridStore.new(db, name)
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gs.send(:delete_chunks)
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gs.collection.remove('_id' => gs.files_id)
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end
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end
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class << self
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alias_method :delete, :unlink
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end
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# Rename a file in this collection. Note that this method uses
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# Collection#update, which means that you will not be notified
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#
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# @param [Mongo::DB] a MongoDB database.
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# @param [String] src the name of the source file.
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# @param [String] dest the name of the destination file.
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# @param [String] root_collection the name of the default root collection.
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def self.mv(db, src, dest, root_collection=DEFAULT_ROOT_COLLECTION)
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db.collection("#{root_collection}.files").update({ :filename => src }, { '$set' => { :filename => dest } })
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end
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# Initialize a GridStore instance for reading, writing, or modifying a given file.
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# Note that it's often easier to work with the various GridStore class methods (open, read, etc.).
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#
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# @param [Mongo::DB] db a MongoDB database.
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# @param [String] name a filename.
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# @param [String] mode either 'r', 'w', or 'w+' for reading, writing, or appending, respectively.
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#
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# @option options [String] :root DEFAULT_ROOT_COLLECTION ('r', 'w', 'w+') the name of the root collection to use.
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#
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# @option options [String] :metadata ({}) (w, w+) A hash containing any data you want persisted as
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# this file's metadata.
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#
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# @option options [Integer] :chunk_size (Chunk::DEFAULT_CHUNK_SIZE) (w) Sets chunk size for files opened for writing.
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# See also GridStore#chunk_size=.
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#
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# @option options [String] :content_type ('text/plain') Set the content type stored as the
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# file's metadata. See also GridStore#content_type=.
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def initialize(db, name, mode='r', options={})
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@db, @filename, @mode = db, name, mode
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@root = options[:root] || DEFAULT_ROOT_COLLECTION
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doc = collection.find({'filename' => @filename}).next_document
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if doc
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@files_id = doc['_id']
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@content_type = doc['contentType']
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@chunk_size = doc['chunkSize']
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@upload_date = doc['uploadDate']
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@aliases = doc['aliases']
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@length = doc['length']
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@metadata = doc['metadata']
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@md5 = doc['md5']
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else
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@files_id = Mongo::ObjectID.new
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@content_type = DEFAULT_CONTENT_TYPE
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@chunk_size = Chunk::DEFAULT_CHUNK_SIZE
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@length = 0
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end
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case mode
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when 'r'
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@curr_chunk = nth_chunk(0)
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@position = 0
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when 'w'
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chunk_collection.create_index([['files_id', Mongo::ASCENDING], ['n', Mongo::ASCENDING]])
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delete_chunks
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@curr_chunk = Chunk.new(self, 'n' => 0)
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@content_type = options[:content_type] if options[:content_type]
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@chunk_size = options[:chunk_size] if options[:chunk_size]
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@metadata = options[:metadata] if options[:metadata]
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@position = 0
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when 'w+'
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chunk_collection.create_index([['files_id', Mongo::ASCENDING], ['n', Mongo::ASCENDING]])
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@curr_chunk = nth_chunk(last_chunk_number) || Chunk.new(self, 'n' => 0) # might be empty
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@curr_chunk.pos = @curr_chunk.data.length if @curr_chunk
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@metadata = options[:metadata] if options[:metadata]
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@position = @length
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else
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raise "error: illegal mode #{mode}"
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end
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@lineno = 0
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@pushback_byte = nil
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end
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# Get the files collection referenced by this GridStore instance.
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#
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# @return [Mongo::Collection]
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def collection
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@db.collection("#{@root}.files")
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end
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# Get the chunk collection referenced by this GridStore.
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#
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# @return [Mongo::Collection]
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def chunk_collection
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@db.collection("#{@root}.chunks")
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end
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# Change the chunk size. This is permitted only when the file is opened for write
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# and no data has yet been written.
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#
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# @param [Integer] size the new chunk size, in bytes.
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#
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# @return [Integer] the new chunk size.
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def chunk_size=(size)
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unless @mode[0] == ?w && @position == 0 && @upload_date == nil
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raise "error: can only change chunk size if open for write and no data written."
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end
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@chunk_size = size
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end
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# ================ reading ================
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def getc
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if @pushback_byte
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byte = @pushback_byte
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@pushback_byte = nil
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@position += 1
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byte
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elsif eof?
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nil
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else
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if @curr_chunk.eof?
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@curr_chunk = nth_chunk(@curr_chunk.chunk_number + 1)
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end
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@position += 1
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@curr_chunk.getc
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end
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end
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def gets(separator=$/)
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str = ''
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byte = self.getc
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return nil if byte == nil # EOF
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while byte != nil
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s = byte.chr
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str << s
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break if s == separator
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byte = self.getc
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end
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@lineno += 1
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str
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end
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def read(len=nil, buf=nil)
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if len
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read_partial(len, buf)
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else
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read_all(buf)
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end
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end
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def readchar
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byte = self.getc
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raise EOFError.new if byte == nil
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byte
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end
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def readline(separator=$/)
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line = gets
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raise EOFError.new if line == nil
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line
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end
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def readlines(separator=$/)
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read.split(separator).collect { |line| "#{line}#{separator}" }
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end
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def each
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line = gets
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while line
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yield line
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line = gets
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end
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end
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alias_method :each_line, :each
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def each_byte
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byte = self.getc
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while byte
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yield byte
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byte = self.getc
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end
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end
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def ungetc(byte)
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@pushback_byte = byte
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@position -= 1
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end
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# ================ writing ================
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def putc(byte)
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if @curr_chunk.pos == @chunk_size
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prev_chunk_number = @curr_chunk.chunk_number
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@curr_chunk.save
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@curr_chunk = Chunk.new(self, 'n' => prev_chunk_number + 1)
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end
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@position += 1
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@curr_chunk.putc(byte)
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end
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def print(*objs)
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objs = [$_] if objs == nil || objs.empty?
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objs.each { |obj|
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str = obj.to_s
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str.each_byte { |byte| self.putc(byte) }
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}
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nil
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end
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def puts(*objs)
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if objs == nil || objs.empty?
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self.putc(10)
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else
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print(*objs.collect{ |obj|
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str = obj.to_s
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str << "\n" unless str =~ /\n$/
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str
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})
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end
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nil
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end
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def <<(obj)
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write(obj.to_s)
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end
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def write(string)
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raise "#@filename not opened for write" unless @mode[0] == ?w
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to_write = string.length
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while (to_write > 0) do
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if @curr_chunk && @curr_chunk.data.position == @chunk_size
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prev_chunk_number = @curr_chunk.chunk_number
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@curr_chunk = GridFS::Chunk.new(self, 'n' => prev_chunk_number + 1)
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end
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chunk_available = @chunk_size - @curr_chunk.data.position
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step_size = (to_write > chunk_available) ? chunk_available : to_write
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@curr_chunk.data.put_array(ByteBuffer.new(string[-to_write,step_size]).to_a)
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to_write -= step_size
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@curr_chunk.save
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end
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string.length - to_write
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end
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# A no-op.
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def flush
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end
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# ================ status ================
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def eof
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raise IOError.new("stream not open for reading") unless @mode[0] == ?r
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@position >= @length
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end
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alias_method :eof?, :eof
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# ================ positioning ================
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def rewind
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if @curr_chunk.chunk_number != 0
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if @mode[0] == ?w
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delete_chunks
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@curr_chunk = Chunk.new(self, 'n' => 0)
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else
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@curr_chunk == nth_chunk(0)
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end
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end
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@curr_chunk.pos = 0
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@lineno = 0
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@position = 0
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end
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def seek(pos, whence=IO::SEEK_SET)
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target_pos = case whence
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when IO::SEEK_CUR
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@position + pos
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when IO::SEEK_END
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@length + pos
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when IO::SEEK_SET
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pos
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end
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new_chunk_number = (target_pos / @chunk_size).to_i
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if new_chunk_number != @curr_chunk.chunk_number
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@curr_chunk.save if @mode[0] == ?w
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@curr_chunk = nth_chunk(new_chunk_number)
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end
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@position = target_pos
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@curr_chunk.pos = @position % @chunk_size
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0
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end
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def tell
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@position
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end
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#---
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# ================ closing ================
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#+++
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def close
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if @mode[0] == ?w
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if @curr_chunk
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@curr_chunk.truncate
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@curr_chunk.save if @curr_chunk.pos > 0
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end
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files = collection
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if @upload_date
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files.remove('_id' => @files_id)
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else
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@upload_date = Time.now
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end
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files.insert(to_mongo_object)
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end
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@db = nil
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end
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def closed?
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@db == nil
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end
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#---
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# ================ protected ================
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#+++
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protected
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def to_mongo_object
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h = OrderedHash.new
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h['_id'] = @files_id
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h['filename'] = @filename
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h['contentType'] = @content_type
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h['length'] = @curr_chunk ? @curr_chunk.chunk_number * @chunk_size + @curr_chunk.pos : 0
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h['chunkSize'] = @chunk_size
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h['uploadDate'] = @upload_date
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h['aliases'] = @aliases
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h['metadata'] = @metadata
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md5_command = OrderedHash.new
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md5_command['filemd5'] = @files_id
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md5_command['root'] = @root
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h['md5'] = @db.command(md5_command)['md5']
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h
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end
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def read_partial(len, buf=nil)
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buf ||= ''
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byte = self.getc
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while byte != nil && (len == nil || len > 0)
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buf << byte.chr
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len -= 1 if len
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byte = self.getc if (len == nil || len > 0)
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end
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buf
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end
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def read_all(buf=nil)
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buf ||= ''
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while true do
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if (@curr_chunk.pos > 0)
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data = @curr_chunk.data.to_s
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buf += data[@position, data.length]
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else
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buf += @curr_chunk.data.to_s
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end
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break if @curr_chunk.chunk_number == last_chunk_number
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@curr_chunk = nth_chunk(@curr_chunk.chunk_number + 1)
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end
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buf
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end
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def delete_chunks
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chunk_collection.remove({'files_id' => @files_id}) if @files_id
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@curr_chunk = nil
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end
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def nth_chunk(n)
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mongo_chunk = chunk_collection.find({'files_id' => @files_id, 'n' => n}).next_document
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Chunk.new(self, mongo_chunk || {})
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end
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def last_chunk_number
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(@length / @chunk_size).to_i
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end
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end
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end
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