418 lines
11 KiB
Ruby
418 lines
11 KiB
Ruby
require 'mongo/types/dbref'
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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 XGen
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module Mongo
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module GridFS
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# GridStore is an IO-like object that provides input and output for
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# streams of data to Mongo. See Mongo's documentation about GridFS for
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# storage implementation details.
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#
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# Example code:
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#
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# require 'mongo/gridfs'
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# GridStore.open(database, 'filename', 'w') { |f|
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# f.puts "Hello, world!"
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# }
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# GridStore.open(database, 'filename, 'r') { |f|
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# puts f.read # => Hello, world!\n
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# }
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# GridStore.open(database, 'filename', 'w+') { |f|
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# f.puts "But wait, there's more!"
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# }
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# GridStore.open(database, 'filename, 'r') { |f|
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# puts f.read # => Hello, world!\nBut wait, there's more!\n
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# }
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class GridStore
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DEFAULT_ROOT_COLLECTION = 'gridfs'
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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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attr_reader :object_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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class << self
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def exist?(db, name)
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db.collection('_files').find({'filename' => name}).next_object.nil?
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end
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def 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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def read(db, name, length=nil, offset=nil)
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GridStore.open(db, name, 'r') { |gs|
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gs.seek(offset) if offset
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gs.read(length)
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}
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end
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def readlines(db, name, separator=$/)
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GridStore.open(db, name, 'r') { |gs|
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gs.readlines(separator)
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}
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end
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def unlink(db, *names)
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names.each { |name|
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gs = GridStore.new(db, name)
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gs.send(:delete_chunks)
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db.collection('_files').remove('_id' => gs.object_id)
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}
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end
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alias_method :delete, :unlink
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end
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#---
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# ================================================================
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#+++
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# Mode may only be 'r', 'w', or 'w+'.
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#
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# Options:
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#
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# :chunk_size :: Ignored if mode is 'r' or 'w+'. Sets chunk size for
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# files opened for writing ('w'). See also #chunk_size=
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# which may only be called before any data is written.
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#
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# :content_type :: Ignored if mode is 'r' or 'w+'. String. Default
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# value is DEFAULT_CONTENT_TYPE. See also
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# #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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doc = @db.collection('_files').find({'filename' => @filename}).next_object
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if doc
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@object_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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fc_id = doc['next']
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if fc_id
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coll = @db.collection('_chunks')
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row = coll.find({'_id' => fc_id.object_id}).next_object
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@first_chunk = row ? Chunk.new(coll, row) : nil
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else
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@first_chunk = nil
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end
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else
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@upload_date = Time.new
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@chunk_size = Chunk::DEFAULT_CHUNK_SIZE
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@content_type = DEFAULT_CONTENT_TYPE
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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 = @first_chunk
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when 'w'
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delete_chunks
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@first_chunk = @curr_chunk = nil
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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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when 'w+'
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@curr_chunk = find_last_chunk
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@curr_chunk.pos = @curr_chunk.data.length if @curr_chunk
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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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# Change chunk size. Can only change if the file is opened for write
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# and the first chunk's size is zero.
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def chunk_size=(size)
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unless @mode[0] == ?w && @first_chunk == 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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#---
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# ================ reading ================
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#+++
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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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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 = @curr_chunk.next
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end
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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 = 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 = 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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buf ||= ''
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byte = 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 = 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 readchar
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byte = 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 = getc
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while byte
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yield byte
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byte = 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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end
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#---
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# ================ writing ================
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#+++
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def putc(byte)
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chunks = @db.collection('_chunks')
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if @curr_chunk == nil
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@first_chunk = @curr_chunk = Chunk.new(chunks, 'cn' => 1)
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elsif @curr_chunk.pos == @chunk_size
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prev_chunk = @curr_chunk
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@curr_chunk = Chunk.new(chunks, 'cn' => prev_chunk.chunk_number + 1)
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prev_chunk.next = @curr_chunk
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prev_chunk.save
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end
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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 = [$_] if objs == nil || objs.empty?
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objs.each { |obj|
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str = obj.to_s
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str.each_byte { |byte| putc(byte) }
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}
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nil
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end
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def puts(*objs)
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if objs == nil || objs.empty?
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putc(10)
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else
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print(*objs.collect{ |obj|
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str = obj.to_s
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str << "\n" unless str =~ /\n$/
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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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# Writes +string+ as bytes and returns the number of bytes written.
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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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count = 0
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string.each_byte { |byte|
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putc byte
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count += 1
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}
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count
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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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#---
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# ================ status ================
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#+++
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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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@curr_chunk == nil || (@curr_chunk.eof? && !@curr_chunk.has_next?)
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end
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alias_method :eof?, :eof
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#---
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# ================ positioning ================
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#+++
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def rewind
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if @curr_chunk != @first_chunk
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@curr_chunk.save unless @curr_chunk == nil || @curr_chunk.empty?
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@curr_chunk == @first_chunk
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end
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@curr_chunk.pos = 0
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@lineno = 0
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# TODO if writing, delete all other chunks on first write
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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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# tell + pos
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# when IO::SEEK_END
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# @curr_chunk.save if @curr_chunk
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# target_chunk_num = ((pos / @chunk_size) + 1).to_i
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# target_chunk_pos = pos % @chunk_size
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# if @curr_chunk == nil || @curr_chunk.chunk_number != target_chunk_num
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# end
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# @curr_chunk.pos = target_chunk_pos
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# 0
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# TODO
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raise "not yet implemented"
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end
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def tell
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return 0 unless @curr_chunk
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@chunk_size * (@curr_chunk.chunk_number - 1) + @curr_chunk.pos
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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
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end
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files = @db.collection('_files')
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if @object_id
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files.remove('_id' => @object_id)
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else
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@object_id = XGen::Mongo::Driver::ObjectID.new
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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'] = @object_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 - 1) * @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['next'] = XGen::Mongo::Driver::DBRef.new(nil, nil, @db, '_chunks', @first_chunk.object_id) if @first_chunk
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h
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end
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def find_last_chunk
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chunk = @curr_chunk || @first_chunk
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while chunk.has_next?
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chunk = chunk.next
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end
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chunk
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end
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def save_chunk(chunk)
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chunks = @db.collection('_chunks')
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end
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def delete_chunks
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chunk = @first_chunk
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coll = @db.collection('_chunks')
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while chunk
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next_chunk = chunk.next
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coll.remove({'_id' => chunk.object_id})
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chunk = next_chunk
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end
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@first_chunk = @curr_chunk = nil
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end
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end
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end
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end
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end
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