Class: GRPC::ClientStub

Inherits:
Object
  • Object
show all
Includes:
Core::StatusCodes, GRPC::Core::TimeConsts
Defined in:
lib/grpc/generic/client_stub.rb

Overview

ClientStub represents an endpoint used to send requests to GRPC servers.

Constant Summary collapse

DEFAULT_TIMEOUT =

Default timeout is 5 seconds.

5

Class Method Summary collapse

Instance Method Summary collapse

Methods included from GRPC::Core::TimeConsts

from_relative_time

Constructor Details

#initialize(host, q, channel_override: nil, timeout: nil, creds: nil, update_metadata: nil, **kw) ⇒ ClientStub

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)

Any arbitrary keyword arguments are treated as channel arguments used to configure the RPC connection to the host.

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::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

  • :update_metadata

when present, this a func that takes a hash and returns a hash it can be used to update metadata, i.e, remove, change or update amend metadata values.

Parameters:

  • host (String) —

    the host the stub connects to

  • q (Core::CompletionQueue) —

    used to wait for events

  • channel_override (Core::Channel) (defaults to: nil) —

    a pre-created channel

  • timeout (Number) (defaults to: nil) —

    the default timeout to use in requests

  • creds (Core::Credentials) (defaults to: nil) —

    the channel

  • update_metadata (defaults to: nil) —

    a func that updates metadata as described above

  • kw (KeywordArgs) —

    the channel arguments



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# File 'lib/grpc/generic/client_stub.rb', line 102

def initialize(host, q,
               channel_override: nil,
               timeout: nil,
               creds: nil,
               update_metadata: nil,
               **kw)
  fail(TypeError, '!CompletionQueue') unless q.is_a?(Core::CompletionQueue)
  @queue = q
  @ch = ClientStub.setup_channel(channel_override, host, creds, **kw)
  @update_metadata = ClientStub.check_update_metadata(update_metadata)
  alt_host = kw[Core::Channel::SSL_TARGET]
  @host = alt_host.nil? ? host : alt_host
  @timeout = timeout.nil? ? DEFAULT_TIMEOUT : timeout
end

Class Method Details

.check_update_metadata(update_metadata) ⇒ Object

check_update_metadata is used by #initialize verify that it’s a Proc.



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# File 'lib/grpc/generic/client_stub.rb', line 63

def self.check_update_metadata(update_metadata)
  return update_metadata if update_metadata.nil?
  fail(TypeError, '!is_a?Proc') unless update_metadata.is_a?(Proc)
  update_metadata
end

.setup_channel(alt_chan, host, creds, **kw) ⇒ Object

setup_channel is used by #initialize to constuct a channel from its arguments.



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# File 'lib/grpc/generic/client_stub.rb', line 44

def self.setup_channel(alt_chan, host, creds, **kw)
  unless alt_chan.nil?
    fail(TypeError, '!Channel') unless alt_chan.is_a?(Core::Channel)
    return alt_chan
  end
  return Core::Channel.new(host, kw) if creds.nil?
  fail(TypeError, '!Credentials') unless creds.is_a?(Core::Credentials)
  Core::Channel.new(host, kw, creds)
end

.update_with_jwt_aud_uri(a_hash, host, method) ⇒ Object 



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# File 'lib/grpc/generic/client_stub.rb', line 54

def self.update_with_jwt_aud_uri(a_hash, host, method)
  last_slash_idx, res = method.rindex('/'), a_hash.clone
  return res if last_slash_idx.nil?
  service_name = method[0..(last_slash_idx - 1)]
  res[:jwt_aud_uri] = "https://#{host}#{service_name}"
  res
end

Instance Method Details

#bidi_streamer(method, requests, marshal, unmarshal, timeout = nil, return_op: false, **kw, &blk) ⇒ Enumerator|nil|Operation

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 terminate the RPC correctly the block:

  • must call bidi#writes_done and then

    * either return false as soon as there is no need for other responses

* 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

Keyword Args ==

Unspecified keyword arguments are treated as metadata to be sent to the server.

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.

Parameters:

  • method (String) —

    the RPC method to call on the GRPC server

  • requests (Object) —

    an Enumerable of requests to send

  • marshal (Function) —

    f(obj)->string that marshals requests

  • unmarshal (Function) —

    f(string)->obj that unmarshals responses

  • timeout (Numeric) (defaults to: nil) —

    (optional) the max completion time in seconds

  • blk (Block) —

    when provided, is executed for each response

  • return_op (true|false) (defaults to: false) —

    return an Operation if true

Returns:

  • (Enumerator|nil|Operation) —

    as discussed above



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# File 'lib/grpc/generic/client_stub.rb', line 385

def bidi_streamer(method, requests, marshal, unmarshal, timeout = nil,
                  return_op: false, **kw, &blk)
  c = new_active_call(method, marshal, unmarshal, timeout)
  kw_with_jwt_uri = self.class.update_with_jwt_aud_uri(kw, @host, method)
  md = @update_metadata.nil? ? kw : @update_metadata.call(kw_with_jwt_uri)
  return c.bidi_streamer(requests, **md, &blk) unless return_op

  # return the operation view of the active_call; define #execute
  # as a new method for this instance that invokes #bidi_streamer
  op = c.operation
  op.define_singleton_method(:execute) do
    c.bidi_streamer(requests, **md, &blk)
  end
  op
end

#client_streamer(method, requests, marshal, unmarshal, timeout = nil, return_op: false, **kw) ⇒ Object|Operation

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.

Keyword Args ==

Unspecified keyword arguments are treated as metadata to be sent to the server.

Parameters:

  • method (String) —

    the RPC method to call on the GRPC server

  • requests (Object) —

    an Enumerable of requests to send

  • marshal (Function) —

    f(obj)->string that marshals requests

  • unmarshal (Function) —

    f(string)->obj that unmarshals responses

  • timeout (Numeric) (defaults to: nil) —

    the max completion time in seconds

  • return_op (true|false) (defaults to: false) —

    return an Operation if true

Returns:

  • (Object|Operation) —

    the response received from the server



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# File 'lib/grpc/generic/client_stub.rb', line 212

def client_streamer(method, requests, marshal, unmarshal, timeout = nil,
                    return_op: false, **kw)
  c = new_active_call(method, marshal, unmarshal, timeout)
  kw_with_jwt_uri = self.class.update_with_jwt_aud_uri(kw, @host, method)
  md = @update_metadata.nil? ? kw : @update_metadata.call(kw_with_jwt_uri)
  return c.client_streamer(requests, **md) unless return_op

  # return the operation view of the active_call; define #execute as a
  # new method for this instance that invokes #client_streamer.
  op = c.operation
  op.define_singleton_method(:execute) do
    c.client_streamer(requests, **md)
  end
  op
end

#request_response(method, req, marshal, unmarshal, timeout = nil, return_op: false, **kw) ⇒ Object

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.

Keyword Args ==

Unspecified keyword arguments are treated as metadata to be sent to the server.

Parameters:

  • method (String) —

    the RPC method to call on the GRPC server

  • req (Object) —

    the request sent to the server

  • marshal (Function) —

    f(obj)->string that marshals requests

  • unmarshal (Function) —

    f(string)->obj that unmarshals responses

  • timeout (Numeric) (defaults to: nil) —

    (optional) the max completion time in seconds

  • return_op (true|false) (defaults to: false) —

    return an Operation if true

Returns:

  • (Object) —

    the response received from the server



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# File 'lib/grpc/generic/client_stub.rb', line 154

def request_response(method, req, marshal, unmarshal, timeout = nil,
                     return_op: false, **kw)
  c = new_active_call(method, marshal, unmarshal, timeout)
  kw_with_jwt_uri = self.class.update_with_jwt_aud_uri(kw, @host, method)
  md = @update_metadata.nil? ? kw : @update_metadata.call(kw_with_jwt_uri)
  return c.request_response(req, **md) unless return_op

  # return the operation view of the active_call; define #execute as a
  # new method for this instance that invokes #request_response.
  op = c.operation
  op.define_singleton_method(:execute) do
    c.request_response(req, **md)
  end
  op
end

#server_streamer(method, req, marshal, unmarshal, timeout = nil, return_op: false, **kw, &blk) ⇒ Enumerator|Operation|nil

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.

Parameters:

  • method (String) —

    the RPC method to call on the GRPC server

  • req (Object) —

    the request sent to the server

  • marshal (Function) —

    f(obj)->string that marshals requests

  • unmarshal (Function) —

    f(string)->obj that unmarshals responses

  • timeout (Numeric) (defaults to: nil) —

    the max completion time in seconds

  • return_op (true|false) (defaults to: false) —

    return an Operation if true

  • blk (Block) —

    when provided, is executed for each response

Returns:

  • (Enumerator|Operation|nil) —

    as discussed above



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# File 'lib/grpc/generic/client_stub.rb', line 279

def server_streamer(method, req, marshal, unmarshal, timeout = nil,
                    return_op: false, **kw, &blk)
  c = new_active_call(method, marshal, unmarshal, timeout)
  kw_with_jwt_uri = self.class.update_with_jwt_aud_uri(kw, @host, method)
  md = @update_metadata.nil? ? kw : @update_metadata.call(kw_with_jwt_uri)
  return c.server_streamer(req, **md, &blk) unless return_op

  # return the operation view of the active_call; define #execute
  # as a new method for this instance that invokes #server_streamer
  op = c.operation
  op.define_singleton_method(:execute) do
    c.server_streamer(req, **md, &blk)
  end
  op
end