407 lines
13 KiB
Ruby
407 lines
13 KiB
Ruby
# encoding: UTF-8
|
|
|
|
# Copyright (C) 2008-2010 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.
|
|
|
|
module Mongo
|
|
|
|
# A cursor over query results. Returned objects are hashes.
|
|
class Cursor
|
|
include Mongo::Conversions
|
|
include Enumerable
|
|
|
|
attr_reader :collection, :selector, :fields,
|
|
:order, :hint, :snapshot, :timeout,
|
|
:full_collection_name, :batch_size
|
|
|
|
# Create a new cursor.
|
|
#
|
|
# Note: cursors are created when executing queries using [Collection#find] and other
|
|
# similar methods. Application developers shouldn't have to create cursors manually.
|
|
#
|
|
# @return [Cursor]
|
|
#
|
|
# @core cursors constructor_details
|
|
def initialize(collection, options={})
|
|
@db = collection.db
|
|
@collection = collection
|
|
@connection = @db.connection
|
|
|
|
@selector = convert_selector_for_query(options[:selector])
|
|
@fields = convert_fields_for_query(options[:fields])
|
|
@skip = options[:skip] || 0
|
|
@limit = options[:limit] || 0
|
|
@order = options[:order]
|
|
@hint = options[:hint]
|
|
@snapshot = options[:snapshot]
|
|
@timeout = options[:timeout] || true
|
|
@explain = options[:explain]
|
|
@socket = options[:socket]
|
|
@tailable = options[:tailable] || false
|
|
@batch_size = options[:batch_size] || 0
|
|
|
|
@full_collection_name = "#{@collection.db.name}.#{@collection.name}"
|
|
@cache = []
|
|
@closed = false
|
|
@query_run = false
|
|
end
|
|
|
|
# Get the next document specified the cursor options.
|
|
#
|
|
# @return [Hash, Nil] the next document or Nil if no documents remain.
|
|
def next_document
|
|
refill_via_get_more if num_remaining == 0
|
|
doc = @cache.shift
|
|
|
|
if doc && doc['$err']
|
|
err = doc['$err']
|
|
|
|
# If the server has stopped being the master (e.g., it's one of a
|
|
# pair but it has died or something like that) then we close that
|
|
# connection. The next request will re-open on master server.
|
|
if err == "not master"
|
|
@connection.close
|
|
raise ConnectionFailure, err
|
|
end
|
|
|
|
raise OperationFailure, err
|
|
end
|
|
|
|
doc
|
|
end
|
|
|
|
# Determine whether this cursor has any remaining results.
|
|
#
|
|
# @return [Boolean]
|
|
def has_next?
|
|
num_remaining > 0
|
|
end
|
|
|
|
# Get the size of the result set for this query.
|
|
#
|
|
# @return [Integer] the number of objects in the result set for this query. Does
|
|
# not take limit and skip into account.
|
|
#
|
|
# @raise [OperationFailure] on a database error.
|
|
def count
|
|
command = BSON::OrderedHash["count", @collection.name,
|
|
"query", @selector,
|
|
"fields", @fields]
|
|
response = @db.command(command)
|
|
return response['n'].to_i if Mongo::Support.ok?(response)
|
|
return 0 if response['errmsg'] == "ns missing"
|
|
raise OperationFailure, "Count failed: #{response['errmsg']}"
|
|
end
|
|
|
|
# Sort this cursor's results.
|
|
#
|
|
# This method overrides any sort order specified in the Collection#find
|
|
# method, and only the last sort applied has an effect.
|
|
#
|
|
# @param [Symbol, Array] key_or_list either 1) a key to sort by or 2)
|
|
# an array of [key, direction] pairs to sort by. Direction should
|
|
# be specified as Mongo::ASCENDING (or :ascending / :asc) or Mongo::DESCENDING (or :descending / :desc)
|
|
#
|
|
# @raise [InvalidOperation] if this cursor has already been used.
|
|
#
|
|
# @raise [InvalidSortValueError] if the specified order is invalid.
|
|
def sort(key_or_list, direction=nil)
|
|
check_modifiable
|
|
|
|
if !direction.nil?
|
|
order = [[key_or_list, direction]]
|
|
else
|
|
order = key_or_list
|
|
end
|
|
|
|
@order = order
|
|
self
|
|
end
|
|
|
|
# Limit the number of results to be returned by this cursor.
|
|
#
|
|
# This method overrides any limit specified in the Collection#find method,
|
|
# and only the last limit applied has an effect.
|
|
#
|
|
# @return [Integer] the current number_to_return if no parameter is given.
|
|
#
|
|
# @raise [InvalidOperation] if this cursor has already been used.
|
|
#
|
|
# @core limit limit-instance_method
|
|
def limit(number_to_return=nil)
|
|
return @limit unless number_to_return
|
|
check_modifiable
|
|
raise ArgumentError, "limit requires an integer" unless number_to_return.is_a? Integer
|
|
|
|
@limit = number_to_return
|
|
self
|
|
end
|
|
|
|
# Skips the first +number_to_skip+ results of this cursor.
|
|
# Returns the current number_to_skip if no parameter is given.
|
|
#
|
|
# This method overrides any skip specified in the Collection#find method,
|
|
# and only the last skip applied has an effect.
|
|
#
|
|
# @return [Integer]
|
|
#
|
|
# @raise [InvalidOperation] if this cursor has already been used.
|
|
def skip(number_to_skip=nil)
|
|
return @skip unless number_to_skip
|
|
check_modifiable
|
|
raise ArgumentError, "skip requires an integer" unless number_to_skip.is_a? Integer
|
|
|
|
@skip = number_to_skip
|
|
self
|
|
end
|
|
|
|
# Iterate over each document in this cursor, yielding it to the given
|
|
# block.
|
|
#
|
|
# Iterating over an entire cursor will close it.
|
|
#
|
|
# @yield passes each document to a block for processing.
|
|
#
|
|
# @example if 'comments' represents a collection of comments:
|
|
# comments.find.each do |doc|
|
|
# puts doc['user']
|
|
# end
|
|
def each
|
|
num_returned = 0
|
|
while has_next? && (@limit <= 0 || num_returned < @limit)
|
|
yield next_document
|
|
num_returned += 1
|
|
end
|
|
end
|
|
|
|
# Receive all the documents from this cursor as an array of hashes.
|
|
#
|
|
# Note: use of this method is discouraged - in most cases, it's much more
|
|
# efficient to retrieve documents as you need them by iterating over the cursor.
|
|
#
|
|
# @return [Array] an array of documents.
|
|
#
|
|
# @raise [InvalidOperation] if this cursor has already been used or if
|
|
# this method has already been called on the cursor.
|
|
def to_a
|
|
raise InvalidOperation, "can't call Cursor#to_a on a used cursor" if @query_run
|
|
rows = []
|
|
num_returned = 0
|
|
while has_next? && (@limit <= 0 || num_returned < @limit)
|
|
rows << next_document
|
|
num_returned += 1
|
|
end
|
|
rows
|
|
end
|
|
|
|
# Get the explain plan for this cursor.
|
|
#
|
|
# @return [Hash] a document containing the explain plan for this cursor.
|
|
#
|
|
# @core explain explain-instance_method
|
|
def explain
|
|
c = Cursor.new(@collection, query_options_hash.merge(:limit => -@limit.abs, :explain => true))
|
|
explanation = c.next_document
|
|
c.close
|
|
|
|
explanation
|
|
end
|
|
|
|
# Close the cursor.
|
|
#
|
|
# Note: if a cursor is read until exhausted (read until Mongo::Constants::OP_QUERY or
|
|
# Mongo::Constants::OP_GETMORE returns zero for the cursor id), there is no need to
|
|
# close it manually.
|
|
#
|
|
# Note also: Collection#find takes an optional block argument which can be used to
|
|
# ensure that your cursors get closed.
|
|
#
|
|
# @return [True]
|
|
def close
|
|
if @cursor_id
|
|
message = BSON::ByteBuffer.new([0, 0, 0, 0])
|
|
message.put_int(1)
|
|
message.put_long(@cursor_id)
|
|
@connection.send_message(Mongo::Constants::OP_KILL_CURSORS, message, "cursor.close #{@cursor_id}")
|
|
end
|
|
@cursor_id = 0
|
|
@closed = true
|
|
end
|
|
|
|
# Is this cursor closed?
|
|
#
|
|
# @return [Boolean]
|
|
def closed?; @closed; end
|
|
|
|
# Returns an integer indicating which query options have been selected.
|
|
#
|
|
# @return [Integer]
|
|
#
|
|
# @see http://www.mongodb.org/display/DOCS/Mongo+Wire+Protocol#MongoWireProtocol-Mongo::Constants::OPQUERY
|
|
# The MongoDB wire protocol.
|
|
def query_opts
|
|
opts = 0
|
|
opts |= Mongo::Constants::OP_QUERY_NO_CURSOR_TIMEOUT unless @timeout
|
|
opts |= Mongo::Constants::OP_QUERY_SLAVE_OK if @connection.slave_ok?
|
|
opts |= Mongo::Constants::OP_QUERY_TAILABLE if @tailable
|
|
opts
|
|
end
|
|
|
|
# Get the query options for this Cursor.
|
|
#
|
|
# @return [Hash]
|
|
def query_options_hash
|
|
{ :selector => @selector,
|
|
:fields => @fields,
|
|
:skip => @skip_num,
|
|
:limit => @limit_num,
|
|
:order => @order,
|
|
:hint => @hint,
|
|
:snapshot => @snapshot,
|
|
:timeout => @timeout }
|
|
end
|
|
|
|
# Clean output for inspect.
|
|
def inspect
|
|
"<Mongo::Cursor:0x#{object_id.to_s(16)} namespace='#{@db.name}.#{@collection.name}' " +
|
|
"@selector=#{@selector.inspect}>"
|
|
end
|
|
|
|
private
|
|
|
|
# Convert the +:fields+ parameter from a single field name or an array
|
|
# of fields names to a hash, with the field names for keys and '1' for each
|
|
# value.
|
|
def convert_fields_for_query(fields)
|
|
case fields
|
|
when String, Symbol
|
|
{fields => 1}
|
|
when Array
|
|
return nil if fields.length.zero?
|
|
returning({}) do |hash|
|
|
fields.each { |field| hash[field] = 1 }
|
|
end
|
|
when Hash
|
|
return fields
|
|
end
|
|
end
|
|
|
|
# Set the query selector hash. If the selector is a Code or String object,
|
|
# the selector will be used in a $where clause.
|
|
# See http://www.mongodb.org/display/DOCS/Server-side+Code+Execution
|
|
def convert_selector_for_query(selector)
|
|
case selector
|
|
when Hash
|
|
selector
|
|
when nil
|
|
{}
|
|
when BSON::Code
|
|
warn "Collection#find will no longer take a JavaScript string in future versions. " +
|
|
"Please specify your $where query explicitly."
|
|
{"$where" => selector}
|
|
when String
|
|
warn "Collection#find will no longer take a JavaScript string in future versions. " +
|
|
"Please specify your $where query explicitly."
|
|
{"$where" => BSON::Code.new(selector)}
|
|
end
|
|
end
|
|
|
|
# Return a number of documents remaining for this cursor.
|
|
def num_remaining
|
|
refill_via_get_more if @cache.length == 0
|
|
@cache.length
|
|
end
|
|
|
|
def refill_via_get_more
|
|
return if send_initial_query || @cursor_id.zero?
|
|
message = BSON::ByteBuffer.new([0, 0, 0, 0])
|
|
|
|
# DB name.
|
|
BSON::BSON_RUBY.serialize_cstr(message, "#{@db.name}.#{@collection.name}")
|
|
|
|
# Number of results to return.
|
|
message.put_int(@batch_size)
|
|
|
|
# Cursor id.
|
|
message.put_long(@cursor_id)
|
|
results, @n_received, @cursor_id = @connection.receive_message(Mongo::Constants::OP_GET_MORE, message, "cursor.get_more()", @socket)
|
|
@cache += results
|
|
close_cursor_if_query_complete
|
|
end
|
|
|
|
# Run query the first time we request an object from the wire
|
|
def send_initial_query
|
|
if @query_run
|
|
false
|
|
else
|
|
message = construct_query_message
|
|
results, @n_received, @cursor_id = @connection.receive_message(Mongo::Constants::OP_QUERY, message,
|
|
(query_log_message if @connection.logger), @socket)
|
|
@cache += results
|
|
@query_run = true
|
|
close_cursor_if_query_complete
|
|
true
|
|
end
|
|
end
|
|
|
|
def construct_query_message
|
|
message = BSON::ByteBuffer.new
|
|
message.put_int(query_opts)
|
|
BSON::BSON_RUBY.serialize_cstr(message, "#{@db.name}.#{@collection.name}")
|
|
message.put_int(@skip)
|
|
message.put_int(@limit)
|
|
spec = query_contains_special_fields? ? construct_query_spec : @selector
|
|
message.put_array(BSON::BSON_CODER.serialize(spec, false).to_a)
|
|
message.put_array(BSON::BSON_CODER.serialize(@fields, false).to_a) if @fields
|
|
message
|
|
end
|
|
|
|
def query_log_message
|
|
"#{@db.name}['#{@collection.name}'].find(#{@selector.inspect}, #{@fields ? @fields.inspect : '{}'})" +
|
|
"#{@skip != 0 ? ('.skip(' + @skip.to_s + ')') : ''}#{@limit != 0 ? ('.limit(' + @limit.to_s + ')') : ''}" +
|
|
"#{@order ? ('.sort(' + @order.inspect + ')') : ''}"
|
|
end
|
|
|
|
def construct_query_spec
|
|
return @selector if @selector.has_key?('$query')
|
|
spec = BSON::OrderedHash.new
|
|
spec['$query'] = @selector
|
|
spec['$orderby'] = Mongo::Support.format_order_clause(@order) if @order
|
|
spec['$hint'] = @hint if @hint && @hint.length > 0
|
|
spec['$explain'] = true if @explain
|
|
spec['$snapshot'] = true if @snapshot
|
|
spec
|
|
end
|
|
|
|
# Returns true if the query contains order, explain, hint, or snapshot.
|
|
def query_contains_special_fields?
|
|
@order || @explain || @hint || @snapshot
|
|
end
|
|
|
|
def to_s
|
|
"DBResponse(flags=#@result_flags, cursor_id=#@cursor_id, start=#@starting_from)"
|
|
end
|
|
|
|
def close_cursor_if_query_complete
|
|
close if @limit > 0 && @n_received >= @limit
|
|
end
|
|
|
|
def check_modifiable
|
|
if @query_run || @closed
|
|
raise InvalidOperation, "Cannot modify the query once it has been run or closed."
|
|
end
|
|
end
|
|
end
|
|
end
|