RUBY-312 Enable exhaust-mode queries.

lib/mongo/connection.rb

@@ -462,11 +462,13 @@ module Mongo
     # @param [Socket] socket a socket to use in lieu of checking out a new one.
     # @param [Boolean] command (false) indicate whether this is a command. If this is a command,
     #   the message will be sent to the primary node.
+    # @param [Boolean] command (false) indicate whether the cursor should be exhausted. Set
+    #   this to true only when the OP_QUERY_EXHAUST flag is set.
     #
     # @return [Array]
     #   An array whose indexes include [0] documents returned, [1] number of document received,
     #   and [3] a cursor_id.
-    def receive_message(operation, message, log_message=nil, socket=nil, command=false, read=:primary)
+    def receive_message(operation, message, log_message=nil, socket=nil, command=false, read=:primary, exhaust=false)
       request_id = add_message_headers(message, operation)
       packed_message = message.to_s
       begin
@@ -489,7 +491,7 @@ module Mongo
         result = ''
         @safe_mutexes[sock].synchronize do
           send_message_on_socket(packed_message, sock)
-          result = receive(sock, request_id)
+          result = receive(sock, request_id, exhaust)
         end
       ensure
         if should_checkin
@@ -785,21 +787,38 @@ module Mongo
 
     ## Low-level connection methods.
 
-    def receive(sock, expected_response)
+    def receive(sock, cursor_id, exhaust)
       begin
-      receive_header(sock, expected_response)
+        if exhaust
+          docs = []
+          num_received = 0
+
+          while(cursor_id != 0) do
+            receive_header(sock, cursor_id, exhaust)
             number_received, cursor_id = receive_response_header(sock)
-      read_documents(number_received, cursor_id, sock)
+            new_docs, n = read_documents(number_received, sock)
+            docs += new_docs
+            num_received += n
+          end
+
+          return [docs, num_received, cursor_id]
+        else
+          receive_header(sock, cursor_id, exhaust)
+          number_received, cursor_id = receive_response_header(sock)
+          docs, num_received = read_documents(number_received, sock)
+
+          return [docs, num_received, cursor_id]
+        end
       rescue Mongo::ConnectionFailure => ex
         close
         raise ex
       end
     end
 
-    def receive_header(sock, expected_response)
+    def receive_header(sock, expected_response, exhaust=false)
       header = receive_message_on_socket(16, sock)
       size, request_id, response_to = header.unpack('VVV')
-      if expected_response != response_to
+      if !exhaust && expected_response != response_to
         raise Mongo::ConnectionFailure, "Expected response #{expected_response} but got #{response_to}"
       end
 
@@ -831,7 +850,7 @@ module Mongo
       end
     end
 
-    def read_documents(number_received, cursor_id, sock)
+    def read_documents(number_received, sock)
       docs = []
       number_remaining = number_received
       while number_remaining > 0 do
@@ -841,7 +860,7 @@ module Mongo
         number_remaining -= 1
         docs << BSON::BSON_CODER.deserialize(buf)
       end
-      [docs, number_received, cursor_id]
+      [docs, number_received]
     end
 
     # Constructs a getlasterror message. This method is used exclusively by

lib/mongo/cursor.rb

@@ -115,7 +115,14 @@ module Mongo
     #
     # @return [Hash, Nil] the next document or Nil if no documents remain.
     def next
-      refresh if @cache.length == 0
+      if @cache.length == 0
+        if @query_run && (@options & OP_QUERY_EXHAUST != 0)
+          close
+          return nil
+        else
+          refresh
+        end
+      end
       doc = @cache.shift
 
       if doc && doc['$err']
@@ -428,7 +435,15 @@ module Mongo
 
     # Return the number of documents remaining for this cursor.
     def num_remaining
-      refresh if @cache.length == 0
+      if @cache.length == 0
+        if @query_run && (@options & OP_QUERY_EXHAUST != 0)
+          close
+          return 0
+        else
+          refresh
+        end
+      end
+
       @cache.length
     end
 
@@ -470,7 +485,8 @@ module Mongo
         message = construct_query_message
         @connection.instrument(:find, instrument_payload) do
           results, @n_received, @cursor_id = @connection.receive_message(
-            Mongo::Constants::OP_QUERY, message, nil, @socket, @command, @read_preference)
+            Mongo::Constants::OP_QUERY, message, nil, @socket, @command,
+            @read_preference, @options & OP_QUERY_EXHAUST != 0)
           @returned += @n_received
           @cache += results
           @query_run = true

test/cursor_test.rb

@@ -50,6 +50,33 @@ class CursorTest < Test::Unit::TestCase
     end
   end
 
+  def test_exhaust
+    if @@version >= "2.0"
+      @@coll.remove
+      data = "1" * 100_000
+      10_000.times do |n|
+        @@coll.insert({:n => n, :data => data})
+      end
+
+      c = Cursor.new(@@coll)
+      c.add_option(OP_QUERY_EXHAUST)
+      assert_equal @@coll.count, c.to_a.size
+      assert c.closed?
+
+      c = Cursor.new(@@coll)
+      c.add_option(OP_QUERY_EXHAUST)
+      9999.times do
+        c.next
+      end
+      assert c.has_next?
+      assert c.next
+      assert !c.has_next?
+      assert c.closed?
+
+      @@coll.remove
+    end
+  end
+
   def test_inspect
     selector = {:a => 1}
     cursor = @@coll.find(selector)