class GRPC::ClientStub
ClientStub
represents a client connection to a gRPC server, and can be used to send requests.
Constants
- DEFAULT_TIMEOUT
Default timeout is infinity.
Attributes
Allows users of the stub to modify the propagate mask.
This is an advanced feature for use when making calls to another gRPC server whilst running in the handler of an existing one.
Public Class Methods
Creates a new ClientStub
.
Minimally, a stub is created with the just the host of the gRPC service it wishes to access, e.g.,
my_stub = ClientStub.new(example.host.com:50505, :this_channel_is_insecure)
If a channel_override argument is passed, it will be used as the underlying channel. Otherwise, the channel_args argument will be used to construct a new underlying channel.
There are some specific keyword args that are not used to configure the channel:
-
:channel_override
when present, this must be a pre-created GRPC::Core::Channel. If it's present the host and arbitrary keyword arg areignored, and the RPC connection uses this channel.
-
:timeout
when present, this is the default timeout used for calls
@param host [String] the host the stub connects to @param creds [Core::ChannelCredentials|Symbol] the channel credentials, or
:this_channel_is_insecure, which explicitly indicates that the client should be created with an insecure connection. Note: this argument is ignored if the channel_override argument is provided.
@param channel_override [Core::Channel] a pre-created channel @param timeout [Number] the default timeout to use in requests @param propagate_mask
[Number] A bitwise combination of flags in
GRPC::Core::PropagateMasks. Indicates how data should be propagated from parent server calls to child client calls if this client is being used within a gRPC server.
@param channel_args [Hash] the channel arguments. Note: this argument is
ignored if the channel_override argument is provided.
@param interceptors [Array<GRPC::ClientInterceptor>] An array of
GRPC::ClientInterceptor objects that will be used for intercepting calls before they are executed Interceptors are an EXPERIMENTAL API.
# File src/ruby/lib/grpc/generic/client_stub.rb, line 98 def initialize(host, creds, channel_override: nil, timeout: nil, propagate_mask: nil, channel_args: {}, interceptors: []) @ch = ClientStub.setup_channel(channel_override, host, creds, channel_args.dup) alt_host = channel_args[Core::Channel::SSL_TARGET] @host = alt_host.nil? ? host : alt_host @propagate_mask = propagate_mask @timeout = timeout.nil? ? DEFAULT_TIMEOUT : timeout @interceptors = InterceptorRegistry.new(interceptors) end
setup_channel
is used by initialize to constuct a channel from its arguments.
# File src/ruby/lib/grpc/generic/client_stub.rb, line 33 def self.setup_channel(alt_chan, host, creds, channel_args = {}) unless alt_chan.nil? fail(TypeError, '!Channel') unless alt_chan.is_a?(Core::Channel) return alt_chan end if channel_args['grpc.primary_user_agent'].nil? channel_args['grpc.primary_user_agent'] = '' else channel_args['grpc.primary_user_agent'] += ' ' end channel_args['grpc.primary_user_agent'] += "grpc-ruby/#{VERSION}" unless creds.is_a?(Core::ChannelCredentials) || creds.is_a?(Core::XdsChannelCredentials) || creds.is_a?(Symbol) fail(TypeError, 'creds is not a ChannelCredentials, XdsChannelCredentials, or Symbol') end Core::Channel.new(host, channel_args, creds) end
Public Instance Methods
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.
Flow Control ==¶ ↑
This is a blocking call.
-
the call completes when the next call to provided block returns false
-
the execution block parameters are two objects for sending and receiving responses, each of which blocks waiting for flow control. E.g, calles to bidi_call#remote_send will wait until flow control allows another write before returning; and obviously calls to responses#next block until the next response is available.
Termination ==¶ ↑
As well as sending and receiving messages, the block passed to the function is also responsible for:
-
calling bidi_call#writes_done to indicate no further reqs will be sent.
-
returning false if once the bidi stream is functionally completed.
Note that response#next will indicate that there are no further responses by throwing StopIteration, but can only happen either if bidi_call#writes_done is called.
To properly terminate the RPC, the responses should be completely iterated through; one way to do this is to loop on responses#next until no further responses are available.
Errors ==¶ ↑
An RuntimeError is raised if
-
the server responds with a non-OK status when any response is
-
retrieved
-
the deadline is exceeded
Return Value ==¶ ↑
if the return_op is false, the return value is an Enumerator of the results, unless a block is provided, in which case the block is executed with each response.
if return_op is true, the function returns an Operation whose execute method runs the Bidi call. Again, Operation#execute either calls a given block with each response or returns an Enumerator of the responses.
@param method [String] the RPC method to call on the GRPC
server @param requests [Object] an Enumerable of requests to send @param marshal [Function] f(obj)->string that marshals requests @param unmarshal [Function] f(string)->obj that unmarshals responses @param deadline [Time] (optional) the time the request should complete @param return_op [true|false] return an Operation if true @param parent [Core::Call] a prior call whose reserved metadata
will be propagated by this one.
@param credentials [Core::CallCredentials] credentials to use when making
the call
@param metadata [Hash] metadata to be sent to the server @param blk [Block] when provided, is executed for each response @return [Enumerator|nil|Operation] as discussed above
# File src/ruby/lib/grpc/generic/client_stub.rb, line 440 def bidi_streamer(method, requests, marshal, unmarshal, deadline: nil, return_op: false, parent: nil, credentials: nil, metadata: {}, &blk) c = new_active_call(method, marshal, unmarshal, deadline: deadline, parent: parent, credentials: credentials) interception_context = @interceptors.build_context intercept_args = { method: method, requests: requests, call: c.interceptable, metadata: metadata } if return_op # return the operation view of the active_call; define #execute # as a new method for this instance that invokes #bidi_streamer c.merge_metadata_to_send(metadata) op = c.operation op.define_singleton_method(:execute) do interception_context.intercept!(:bidi_streamer, intercept_args) do c.bidi_streamer(requests, &blk) end end op else interception_context.intercept!(:bidi_streamer, intercept_args) do c.bidi_streamer(requests, metadata: metadata, &blk) end end 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.
Flow Control ==¶ ↑
This is a blocking call.
-
it does not return until a response is received.
-
each requests is sent only when
GRPC
core's flow control allows it to be sent.
Errors ==¶ ↑
An RuntimeError is raised if
-
the server responds with a non-OK status
-
the deadline is exceeded
Return Value ==¶ ↑
If return_op is false, the call consumes the requests and returns the response.
If return_op is true, the call returns the response.
@param method [String] the RPC method to call on the GRPC
server @param requests [Object] an Enumerable of requests to send @param marshal [Function] f(obj)->string that marshals requests @param unmarshal [Function] f(string)->obj that unmarshals responses @param deadline [Time] (optional) the time the request should complete @param return_op [true|false] return an Operation if true @param parent [Core::Call] a prior call whose reserved metadata
will be propagated by this one.
@param credentials [Core::CallCredentials] credentials to use when making
the call
@param metadata [Hash] metadata to be sent to the server @return [Object|Operation] the response received from the server
# File src/ruby/lib/grpc/generic/client_stub.rb, line 227 def client_streamer(method, requests, marshal, unmarshal, deadline: nil, return_op: false, parent: nil, credentials: nil, metadata: {}) c = new_active_call(method, marshal, unmarshal, deadline: deadline, parent: parent, credentials: credentials) interception_context = @interceptors.build_context intercept_args = { method: method, requests: requests, call: c.interceptable, metadata: metadata } if return_op # return the operation view of the active_call; define #execute as a # new method for this instance that invokes #client_streamer. c.merge_metadata_to_send(metadata) op = c.operation op.define_singleton_method(:execute) do interception_context.intercept!(:client_streamer, intercept_args) do c.client_streamer(requests) end end op else interception_context.intercept!(:client_streamer, intercept_args) do c.client_streamer(requests, metadata: metadata) end end end
request_response
sends a request to a GRPC
server, and returns the response.
Flow Control ==¶ ↑
This is a blocking call.
-
it does not return until a response is received.
-
the requests is sent only when
GRPC
core's flow control allows it to be sent.
Errors ==¶ ↑
An RuntimeError is raised if
-
the server responds with a non-OK status
-
the deadline is exceeded
Return Value ==¶ ↑
If return_op is false, the call returns the response
If return_op is true, the call returns an Operation, calling execute on the Operation returns the response.
@param method [String] the RPC method to call on the GRPC
server @param req [Object] the request sent to the server @param marshal [Function] f(obj)->string that marshals requests @param unmarshal [Function] f(string)->obj that unmarshals responses @param deadline [Time] (optional) the time the request should complete @param return_op [true|false] return an Operation if true @param parent [Core::Call] a prior call whose reserved metadata
will be propagated by this one.
@param credentials [Core::CallCredentials] credentials to use when making
the call
@param metadata [Hash] metadata to be sent to the server @return [Object] the response received from the server
# File src/ruby/lib/grpc/generic/client_stub.rb, line 150 def request_response(method, req, marshal, unmarshal, deadline: nil, return_op: false, parent: nil, credentials: nil, metadata: {}) c = new_active_call(method, marshal, unmarshal, deadline: deadline, parent: parent, credentials: credentials) interception_context = @interceptors.build_context intercept_args = { method: method, request: req, call: c.interceptable, metadata: metadata } if return_op # return the operation view of the active_call; define #execute as a # new method for this instance that invokes #request_response. c.merge_metadata_to_send(metadata) op = c.operation op.define_singleton_method(:execute) do interception_context.intercept!(:request_response, intercept_args) do c.request_response(req, metadata: metadata) end end op else interception_context.intercept!(:request_response, intercept_args) do c.request_response(req, metadata: metadata) end end 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.
Flow Control ==¶ ↑
This is a blocking call.
-
the request is sent only when
GRPC
core's flow control allows it to be sent. -
the request will not complete until the server sends the final response followed by a status message.
Errors ==¶ ↑
An RuntimeError is raised if
-
the server responds with a non-OK status when any response is
-
retrieved
-
the deadline is exceeded
Return Value ==¶ ↑
if the return_op is false, the return value is an Enumerator of the results, unless a block is provided, in which case the block is executed with each response.
if return_op is true, the function returns an Operation whose execute method runs server streamer call. Again, Operation#execute either calls the given block with each response or returns an Enumerator of the responses.
Keyword Args ==¶ ↑
Unspecified keyword arguments are treated as metadata to be sent to the server.
@param method [String] the RPC method to call on the GRPC
server @param req [Object] the request sent to the server @param marshal [Function] f(obj)->string that marshals requests @param unmarshal [Function] f(string)->obj that unmarshals responses @param deadline [Time] (optional) the time the request should complete @param return_op [true|false]return an Operation if true @param parent [Core::Call] a prior call whose reserved metadata
will be propagated by this one.
@param credentials [Core::CallCredentials] credentials to use when making
the call
@param metadata [Hash] metadata to be sent to the server @param blk [Block] when provided, is executed for each response @return [Enumerator|Operation|nil] as discussed above
# File src/ruby/lib/grpc/generic/client_stub.rb, line 318 def server_streamer(method, req, marshal, unmarshal, deadline: nil, return_op: false, parent: nil, credentials: nil, metadata: {}, &blk) c = new_active_call(method, marshal, unmarshal, deadline: deadline, parent: parent, credentials: credentials) interception_context = @interceptors.build_context intercept_args = { method: method, request: req, call: c.interceptable, metadata: metadata } if return_op # return the operation view of the active_call; define #execute # as a new method for this instance that invokes #server_streamer c.merge_metadata_to_send(metadata) op = c.operation op.define_singleton_method(:execute) do interception_context.intercept!(:server_streamer, intercept_args) do c.server_streamer(req, &blk) end end op else interception_context.intercept!(:server_streamer, intercept_args) do c.server_streamer(req, metadata: metadata, &blk) end end end
Private Instance Methods
Creates a new active stub
@param method [string] the method being called. @param marshal [Function] f(obj)->string that marshals requests @param unmarshal [Function] f(string)->obj that unmarshals responses @param parent [Grpc::Call] a parent call, available when calls are
made from server
@param credentials [Core::CallCredentials] credentials to use when making
the call
# File src/ruby/lib/grpc/generic/client_stub.rb, line 487 def new_active_call(method, marshal, unmarshal, deadline: nil, parent: nil, credentials: nil) deadline = from_relative_time(@timeout) if deadline.nil? # Provide each new client call with its own completion queue call = @ch.create_call(parent, # parent call @propagate_mask, # propagation options method, nil, # host use nil, deadline) call.set_credentials! credentials unless credentials.nil? ActiveCall.new(call, marshal, unmarshal, deadline, started: false) end