mongo-ruby-driver/lib/mongo/gridfs/grid_store.rb

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# --
# Copyright (C) 2008-2009 10gen Inc.
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
# http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.
# ++
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require 'mongo/types/objectid'
require 'mongo/util/ordered_hash'
require 'mongo/gridfs/chunk'
module GridFS
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# 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 = 'fs'
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
attr_reader :md5
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
# List the contains of all GridFS files stored in the given db and
# root collection.
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#
# :db :: the database to use
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#
# :root_collection :: the root collection to use
def list(db, root_collection=DEFAULT_ROOT_COLLECTION)
db.collection("#{root_collection}.files").find().map { |f|
f['filename']
}
end
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def readlines(db, name, separator=$/)
GridStore.open(db, name, 'r') { |gs|
gs.readlines(separator)
}
end
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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
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end
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#---
# ================================================================
#+++
# 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']
@md5 = doc['md5']
else
@files_id = Mongo::ObjectID.new
@content_type = DEFAULT_CONTENT_TYPE
@chunk_size = Chunk::DEFAULT_CHUNK_SIZE
@length = 0
end
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case mode
when 'r'
@curr_chunk = nth_chunk(0)
@position = 0
when 'w'
chunk_collection.create_index([['files_id', Mongo::ASCENDING], ['n', Mongo::ASCENDING]])
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([['files_id', Mongo::ASCENDING], ['n', Mongo::ASCENDING]])
@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
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@lineno = 0
@pushback_byte = nil
end
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def collection
@db.collection("#{@root}.files")
end
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# Returns collection used for storing chunks. Depends on value of
# @root.
def chunk_collection
@db.collection("#{@root}.chunks")
end
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# 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
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#---
# ================ 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)
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end
@position += 1
@curr_chunk.getc
end
end
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def gets(separator=$/)
str = ''
byte = self.getc
return nil if byte == nil # EOF
while byte != nil
s = byte.chr
str << s
break if s == separator
byte = self.getc
end
@lineno += 1
str
end
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def read(len=nil, buf=nil)
buf ||= ''
byte = self.getc
while byte != nil && (len == nil || len > 0)
buf << byte.chr
len -= 1 if len
byte = self.getc if (len == nil || len > 0)
end
buf
end
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def readchar
byte = self.getc
raise EOFError.new if byte == nil
byte
end
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def readline(separator=$/)
line = gets
raise EOFError.new if line == nil
line
end
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def readlines(separator=$/)
read.split(separator).collect { |line| "#{line}#{separator}" }
end
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def each
line = gets
while line
yield line
line = gets
end
end
alias_method :each_line, :each
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def each_byte
byte = self.getc
while byte
yield byte
byte = self.getc
end
end
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def ungetc(byte)
@pushback_byte = byte
@position -= 1
end
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#---
# ================ writing ================
#+++
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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
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def print(*objs)
objs = [$_] if objs == nil || objs.empty?
objs.each { |obj|
str = obj.to_s
str.each_byte { |byte| self.putc(byte) }
}
nil
end
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def puts(*objs)
if objs == nil || objs.empty?
self.putc(10)
else
print(*objs.collect{ |obj|
str = obj.to_s
str << "\n" unless str =~ /\n$/
str
})
end
nil
end
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def <<(obj)
write(obj.to_s)
end
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# 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|
self.putc byte
count += 1
}
count
end
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# A no-op.
def flush
end
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#---
# ================ status ================
#+++
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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)
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end
end
@curr_chunk.pos = 0
@lineno = 0
@position = 0
end
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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
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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)
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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
md5_command = OrderedHash.new
md5_command['filemd5'] = @files_id
md5_command['root'] = @root
h['md5'] = @db.db_command(md5_command)['md5']
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 || {})
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end
def last_chunk_number
(@length / @chunk_size).to_i
end
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end
end