Initial checkin of gRPC to third_party/

third_party/grpc/src/ruby/lib/grpc/generic/active_call.rb

+# Copyright 2015, Google Inc.
+# All rights reserved.
+#
+# Redistribution and use in source and binary forms, with or without
+# modification, are permitted provided that the following conditions are
+# met:
+#
+#     * Redistributions of source code must retain the above copyright
+# notice, this list of conditions and the following disclaimer.
+#     * Redistributions in binary form must reproduce the above
+# copyright notice, this list of conditions and the following disclaimer
+# in the documentation and/or other materials provided with the
+# distribution.
+#     * Neither the name of Google Inc. nor the names of its
+# contributors may be used to endorse or promote products derived from
+# this software without specific prior written permission.
+#
+# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+# "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+# LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+# A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+# OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+# SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+# LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+# DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+# THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+# (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+# OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+require 'forwardable'
+require 'grpc/generic/bidi_call'
+
+class Struct
+  # BatchResult is the struct returned by calls to call#start_batch.
+  class BatchResult
+    # check_status returns the status, raising an error if the status
+    # is non-nil and not OK.
+    def check_status
+      return nil if status.nil?
+      fail GRPC::Cancelled if status.code == GRPC::Core::StatusCodes::CANCELLED
+      if status.code != GRPC::Core::StatusCodes::OK
+        GRPC.logger.debug("Failing with status #{status}")
+        # raise BadStatus, propagating the metadata if present.
+        md = status.metadata
+        with_sym_keys = Hash[md.each_pair.collect { |x, y| [x.to_sym, y] }]
+        fail GRPC::BadStatus.new(status.code, status.details, **with_sym_keys)
+      end
+      status
+    end
+  end
+end
+
+# GRPC contains the General RPC module.
+module GRPC
+  # The ActiveCall class provides simple methods for sending marshallable
+  # data to a call
+  class ActiveCall
+    include Core::TimeConsts
+    include Core::CallOps
+    extend Forwardable
+    attr_reader(:deadline)
+    def_delegators :@call, :cancel, :metadata, :write_flag, :write_flag=
+
+    # client_invoke begins a client invocation.
+    #
+    # Flow Control note: this blocks until flow control accepts that client
+    # request can go ahead.
+    #
+    # deadline is the absolute deadline for the call.
+    #
+    # == Keyword Arguments ==
+    # any keyword arguments are treated as metadata to be sent to the server
+    # if a keyword value is a list, multiple metadata for it's key are sent
+    #
+    # @param call [Call] a call on which to start and invocation
+    # @param q [CompletionQueue] the completion queue
+    def self.client_invoke(call, q, **kw)
+      fail(TypeError, '!Core::Call') unless call.is_a? Core::Call
+      unless q.is_a? Core::CompletionQueue
+        fail(TypeError, '!Core::CompletionQueue')
+      end
+      metadata_tag = Object.new
+      call.run_batch(q, metadata_tag, INFINITE_FUTURE,
+                     SEND_INITIAL_METADATA => kw)
+      metadata_tag
+    end
+
+    # Creates an ActiveCall.
+    #
+    # ActiveCall should only be created after a call is accepted.  That
+    # means different things on a client and a server.  On the client, the
+    # call is accepted after calling call.invoke.  On the server, this is
+    # after call.accept.
+    #
+    # #initialize cannot determine if the call is accepted or not; so if a
+    # call that's not accepted is used here, the error won't be visible until
+    # the ActiveCall methods are called.
+    #
+    # deadline is the absolute deadline for the call.
+    #
+    # @param call [Call] the call used by the ActiveCall
+    # @param q [CompletionQueue] the completion queue used to accept
+    #          the call
+    # @param marshal [Function] f(obj)->string that marshal requests
+    # @param unmarshal [Function] f(string)->obj that unmarshals responses
+    # @param deadline [Fixnum] the deadline for the call to complete
+    # @param metadata_tag [Object] the object use obtain metadata for clients
+    # @param started [true|false] indicates if the call has begun
+    def initialize(call, q, marshal, unmarshal, deadline, started: true,
+                   metadata_tag: nil)
+      fail(TypeError, '!Core::Call') unless call.is_a? Core::Call
+      unless q.is_a? Core::CompletionQueue
+        fail(TypeError, '!Core::CompletionQueue')
+      end
+      @call = call
+      @cq = q
+      @deadline = deadline
+      @marshal = marshal
+      @started = started
+      @unmarshal = unmarshal
+      @metadata_tag = metadata_tag
+      @op_notifier = nil
+    end
+
+    # output_metadata are provides access to hash that can be used to
+    # save metadata to be sent as trailer
+    def output_metadata
+      @output_metadata ||= {}
+    end
+
+    # cancelled indicates if the call was cancelled
+    def cancelled
+      !@call.status.nil? && @call.status.code == Core::StatusCodes::CANCELLED
+    end
+
+    # multi_req_view provides a restricted view of this ActiveCall for use
+    # in a server client-streaming handler.
+    def multi_req_view
+      MultiReqView.new(self)
+    end
+
+    # single_req_view provides a restricted view of this ActiveCall for use in
+    # a server request-response handler.
+    def single_req_view
+      SingleReqView.new(self)
+    end
+
+    # operation provides a restricted view of this ActiveCall for use as
+    # a Operation.
+    def operation
+      @op_notifier = Notifier.new
+      Operation.new(self)
+    end
+
+    # writes_done indicates that all writes are completed.
+    #
+    # It blocks until the remote endpoint acknowledges with at status unless
+    # assert_finished is set to false.  Any calls to #remote_send after this
+    # call will fail.
+    #
+    # @param assert_finished [true, false] when true(default), waits for
+    # FINISHED.
+    def writes_done(assert_finished = true)
+      ops = {
+        SEND_CLOSE_FROM_CLIENT => nil
+      }
+      ops[RECV_STATUS_ON_CLIENT] = nil if assert_finished
+      batch_result = @call.run_batch(@cq, self, INFINITE_FUTURE, ops)
+      return unless assert_finished
+      @call.status = batch_result.status
+      op_is_done
+      batch_result.check_status
+    end
+
+    # finished waits until a client call is completed.
+    #
+    # It blocks until the remote endpoint acknowledges by sending a status.
+    def finished
+      batch_result = @call.run_batch(@cq, self, INFINITE_FUTURE,
+                                     RECV_STATUS_ON_CLIENT => nil)
+      unless batch_result.status.nil?
+        if @call.metadata.nil?
+          @call.metadata = batch_result.status.metadata
+        else
+          @call.metadata.merge!(batch_result.status.metadata)
+        end
+      end
+      @call.status = batch_result.status
+      op_is_done
+      batch_result.check_status
+    end
+
+    # remote_send sends a request to the remote endpoint.
+    #
+    # It blocks until the remote endpoint accepts the message.
+    #
+    # @param req [Object, String] the object to send or it's marshal form.
+    # @param marshalled [false, true] indicates if the object is already
+    # marshalled.
+    def remote_send(req, marshalled = false)
+      GRPC.logger.debug("sending #{req}, marshalled? #{marshalled}")
+      payload = marshalled ? req : @marshal.call(req)
+      @call.run_batch(@cq, self, INFINITE_FUTURE, SEND_MESSAGE => payload)
+    end
+
+    # send_status sends a status to the remote endpoint.
+    #
+    # @param code [int] the status code to send
+    # @param details [String] details
+    # @param assert_finished [true, false] when true(default), waits for
+    # FINISHED.
+    #
+    # == Keyword Arguments ==
+    # any keyword arguments are treated as metadata to be sent to the server
+    # if a keyword value is a list, multiple metadata for it's key are sent
+    def send_status(code = OK, details = '', assert_finished = false, **kw)
+      ops = {
+        SEND_STATUS_FROM_SERVER => Struct::Status.new(code, details, kw)
+      }
+      ops[RECV_CLOSE_ON_SERVER] = nil if assert_finished
+      @call.run_batch(@cq, self, INFINITE_FUTURE, ops)
+      nil
+    end
+
+    # remote_read reads a response from the remote endpoint.
+    #
+    # It blocks until the remote endpoint replies with a message or status.
+    # On receiving a message, it returns the response after unmarshalling it.
+    # On receiving a status, it returns nil if the status is OK, otherwise
+    # raising BadStatus
+    def remote_read
+      ops = { RECV_MESSAGE => nil }
+      ops[RECV_INITIAL_METADATA] = nil unless @metadata_tag.nil?
+      batch_result = @call.run_batch(@cq, self, INFINITE_FUTURE, ops)
+      unless @metadata_tag.nil?
+        @call.metadata = batch_result.metadata
+        @metadata_tag = nil
+      end
+      GRPC.logger.debug("received req: #{batch_result}")
+      unless batch_result.nil? || batch_result.message.nil?
+        GRPC.logger.debug("received req.to_s: #{batch_result.message}")
+        res = @unmarshal.call(batch_result.message)
+        GRPC.logger.debug("received_req (unmarshalled): #{res.inspect}")
+        return res
+      end
+      GRPC.logger.debug('found nil; the final response has been sent')
+      nil
+    end
+
+    # each_remote_read passes each response to the given block or returns an
+    # enumerator the responses if no block is given.
+    #
+    # == Enumerator ==
+    #
+    # * #next blocks until the remote endpoint sends a READ or FINISHED
+    # * for each read, enumerator#next yields the response
+    # * on status
+    #    * if it's is OK, enumerator#next raises StopException
+    #    * if is not OK, enumerator#next raises RuntimeException
+    #
+    # == Block ==
+    #
+    # * if provided it is executed for each response
+    # * the call blocks until no more responses are provided
+    #
+    # @return [Enumerator] if no block was given
+    def each_remote_read
+      return enum_for(:each_remote_read) unless block_given?
+      loop do
+        resp = remote_read
+        break if resp.nil?  # the last response was received
+        yield resp
+      end
+    end
+
+    # each_remote_read_then_finish passes each response to the given block or
+    # returns an enumerator of the responses if no block is given.
+    #
+    # It is like each_remote_read, but it blocks on finishing on detecting
+    # the final message.
+    #
+    # == Enumerator ==
+    #
+    # * #next blocks until the remote endpoint sends a READ or FINISHED
+    # * for each read, enumerator#next yields the response
+    # * on status
+    #    * if it's is OK, enumerator#next raises StopException
+    #    * if is not OK, enumerator#next raises RuntimeException
+    #
+    # == Block ==
+    #
+    # * if provided it is executed for each response
+    # * the call blocks until no more responses are provided
+    #
+    # @return [Enumerator] if no block was given
+    def each_remote_read_then_finish
+      return enum_for(:each_remote_read_then_finish) unless block_given?
+      loop do
+        resp = remote_read
+        break if resp.is_a? Struct::Status  # is an OK status
+        if resp.nil?  # the last response was received, but not finished yet
+          finished
+          break
+        end
+        yield resp
+      end
+    end
+
+    # request_response sends a request to a GRPC server, and returns the
+    # response.
+    #
+    # == Keyword Arguments ==
+    # any keyword arguments are treated as metadata to be sent to the server
+    # if a keyword value is a list, multiple metadata for it's key are sent
+    #
+    # @param req [Object] the request sent to the server
+    # @return [Object] the response received from the server
+    def request_response(req, **kw)
+      start_call(**kw) unless @started
+      remote_send(req)
+      writes_done(false)
+      response = remote_read
+      finished unless response.is_a? Struct::Status
+      response
+    rescue GRPC::Core::CallError => e
+      finished  # checks for Cancelled
+      raise e
+    end
+
+    # client_streamer sends a stream of requests to a GRPC server, and
+    # returns a single response.
+    #
+    # requests provides an 'iterable' of Requests. I.e. it follows Ruby's
+    # #each enumeration protocol. In the simplest case, requests will be an
+    # array of marshallable objects; in typical case it will be an Enumerable
+    # that allows dynamic construction of the marshallable objects.
+    #
+    # == Keyword Arguments ==
+    # any keyword arguments are treated as metadata to be sent to the server
+    # if a keyword value is a list, multiple metadata for it's key are sent
+    #
+    # @param requests [Object] an Enumerable of requests to send
+    # @return [Object] the response received from the server
+    def client_streamer(requests, **kw)
+      start_call(**kw) unless @started
+      requests.each { |r| remote_send(r) }
+      writes_done(false)
+      response = remote_read
+      finished unless response.is_a? Struct::Status
+      response
+    rescue GRPC::Core::CallError => e
+      finished  # checks for Cancelled
+      raise e
+    end
+
+    # server_streamer sends one request to the GRPC server, which yields a
+    # stream of responses.
+    #
+    # responses provides an enumerator over the streamed responses, i.e. it
+    # follows Ruby's #each iteration protocol.  The enumerator blocks while
+    # waiting for each response, stops when the server signals that no
+    # further responses will be supplied.  If the implicit block is provided,
+    # it is executed with each response as the argument and no result is
+    # returned.
+    #
+    # == Keyword Arguments ==
+    # any keyword arguments are treated as metadata to be sent to the server
+    # if a keyword value is a list, multiple metadata for it's key are sent
+    # any keyword arguments are treated as metadata to be sent to the server.
+    #
+    # @param req [Object] the request sent to the server
+    # @return [Enumerator|nil] a response Enumerator
+    def server_streamer(req, **kw)
+      start_call(**kw) unless @started
+      remote_send(req)
+      writes_done(false)
+      replies = enum_for(:each_remote_read_then_finish)
+      return replies unless block_given?
+      replies.each { |r| yield r }
+    rescue GRPC::Core::CallError => e
+      finished  # checks for Cancelled
+      raise e
+    end
+
+    # bidi_streamer sends a stream of requests to the GRPC server, and yields
+    # a stream of responses.
+    #
+    # This method takes an Enumerable of requests, and returns and enumerable
+    # of responses.
+    #
+    # == requests ==
+    #
+    # requests provides an 'iterable' of Requests. I.e. it follows Ruby's
+    # #each enumeration protocol. In the simplest case, requests will be an
+    # array of marshallable objects; in typical case it will be an
+    # Enumerable that allows dynamic construction of the marshallable
+    # objects.
+    #
+    # == responses ==
+    #
+    # This is an enumerator of responses.  I.e, its #next method blocks
+    # waiting for the next response.  Also, if at any point the block needs
+    # to consume all the remaining responses, this can be done using #each or
+    # #collect.  Calling #each or #collect should only be done if
+    # the_call#writes_done has been called, otherwise the block will loop
+    # forever.
+    #
+    # == Keyword Arguments ==
+    # any keyword arguments are treated as metadata to be sent to the server
+    # if a keyword value is a list, multiple metadata for it's key are sent
+    #
+    # @param requests [Object] an Enumerable of requests to send
+    # @return [Enumerator, nil] a response Enumerator
+    def bidi_streamer(requests, **kw, &blk)
+      start_call(**kw) unless @started
+      bd = BidiCall.new(@call, @cq, @marshal, @unmarshal,
+                        metadata_tag: @metadata_tag)
+      @metadata_tag = nil  # run_on_client ensures metadata is read
+      bd.run_on_client(requests, @op_notifier, &blk)
+    end
+
+    # run_server_bidi orchestrates a BiDi stream processing on a server.
+    #
+    # N.B. gen_each_reply is a func(Enumerable<Requests>)
+    #
+    # It takes an enumerable of requests as an arg, in case there is a
+    # relationship between the stream of requests and the stream of replies.
+    #
+    # This does not mean that must necessarily be one.  E.g, the replies
+    # produced by gen_each_reply could ignore the received_msgs
+    #
+    # @param gen_each_reply [Proc] generates the BiDi stream replies
+    def run_server_bidi(gen_each_reply)
+      bd = BidiCall.new(@call, @cq, @marshal, @unmarshal)
+      bd.run_on_server(gen_each_reply)
+    end
+
+    # Waits till an operation completes
+    def wait
+      return if @op_notifier.nil?
+      GRPC.logger.debug("active_call.wait: on #{@op_notifier}")
+      @op_notifier.wait
+    end
+
+    # Signals that an operation is done
+    def op_is_done
+      return if @op_notifier.nil?
+      @op_notifier.notify(self)
+    end
+
+    private
+
+    # Starts the call if not already started
+    def start_call(**kw)
+      return if @started
+      @metadata_tag = ActiveCall.client_invoke(@call, @cq, **kw)
+      @started = true
+    end
+
+    def self.view_class(*visible_methods)
+      Class.new do
+        extend ::Forwardable
+        def_delegators :@wrapped, *visible_methods
+
+        # @param wrapped [ActiveCall] the call whose methods are shielded
+        def initialize(wrapped)
+          @wrapped = wrapped
+        end
+      end
+    end
+
+    # SingleReqView limits access to an ActiveCall's methods for use in server
+    # handlers that receive just one request.
+    SingleReqView = view_class(:cancelled, :deadline, :metadata,
+                               :output_metadata)
+
+    # MultiReqView limits access to an ActiveCall's methods for use in
+    # server client_streamer handlers.
+    MultiReqView = view_class(:cancelled, :deadline, :each_queued_msg,
+                              :each_remote_read, :metadata, :output_metadata)
+
+    # Operation limits access to an ActiveCall's methods for use as
+    # a Operation on the client.
+    Operation = view_class(:cancel, :cancelled, :deadline, :execute,
+                           :metadata, :status, :start_call, :wait, :write_flag,
+                           :write_flag=)
+  end
+end