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// Copyright (c) 2013-2014 Sandstorm Development Group, Inc. and contributors
// Licensed under the MIT License:
//
// Permission is hereby granted, free of charge, to any person obtaining a copy
// of this software and associated documentation files (the "Software"), to deal
// in the Software without restriction, including without limitation the rights
// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
// copies of the Software, and to permit persons to whom the Software is
// furnished to do so, subject to the following conditions:
//
// The above copyright notice and this permission notice shall be included in
// all copies or substantial portions of the Software.
//
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
// THE SOFTWARE.
#include "calculator.capnp.h"
#include <capnp/ez-rpc.h>
#include <kj/debug.h>
#include <math.h>
#include <iostream>
class PowerFunction final: public Calculator::Function::Server {
// An implementation of the Function interface wrapping pow(). Note that
// we're implementing this on the client side and will pass a reference to
// the server. The server will then be able to make calls back to the client.
public:
kj::Promise<void> call(CallContext context) {
auto params = context.getParams().getParams();
KJ_REQUIRE(params.size() == 2, "Wrong number of parameters.");
context.getResults().setValue(pow(params[0], params[1]));
return kj::READY_NOW;
}
};
int main(int argc, const char* argv[]) {
if (argc != 2) {
std::cerr << "usage: " << argv[0] << " HOST:PORT\n"
"Connects to the Calculator server at the given address and "
"does some RPCs." << std::endl;
return 1;
}
capnp::EzRpcClient client(argv[1]);
Calculator::Client calculator = client.getMain<Calculator>();
// Keep an eye on `waitScope`. Whenever you see it used is a place where we
// stop and wait for the server to respond. If a line of code does not use
// `waitScope`, then it does not block!
auto& waitScope = client.getWaitScope();
{
// Make a request that just evaluates the literal value 123.
//
// What's interesting here is that evaluate() returns a "Value", which is
// another interface and therefore points back to an object living on the
// server. We then have to call read() on that object to read it.
// However, even though we are making two RPC's, this block executes in
// *one* network round trip because of promise pipelining: we do not wait
// for the first call to complete before we send the second call to the
// server.
std::cout << "Evaluating a literal... ";
std::cout.flush();
// Set up the request.
auto request = calculator.evaluateRequest();
request.getExpression().setLiteral(123);
// Send it, which returns a promise for the result (without blocking).
auto evalPromise = request.send();
// Using the promise, create a pipelined request to call read() on the
// returned object, and then send that.
auto readPromise = evalPromise.getValue().readRequest().send();
// Now that we've sent all the requests, wait for the response. Until this
// point, we haven't waited at all!
auto response = readPromise.wait(waitScope);
KJ_ASSERT(response.getValue() == 123);
std::cout << "PASS" << std::endl;
}
{
// Make a request to evaluate 123 + 45 - 67.
//
// The Calculator interface requires that we first call getOperator() to
// get the addition and subtraction functions, then call evaluate() to use
// them. But, once again, we can get both functions, call evaluate(), and
// then read() the result -- four RPCs -- in the time of *one* network
// round trip, because of promise pipelining.
std::cout << "Using add and subtract... ";
std::cout.flush();
Calculator::Function::Client add = nullptr;
Calculator::Function::Client subtract = nullptr;
{
// Get the "add" function from the server.
auto request = calculator.getOperatorRequest();
request.setOp(Calculator::Operator::ADD);
add = request.send().getFunc();
}
{
// Get the "subtract" function from the server.
auto request = calculator.getOperatorRequest();
request.setOp(Calculator::Operator::SUBTRACT);
subtract = request.send().getFunc();
}
// Build the request to evaluate 123 + 45 - 67.
auto request = calculator.evaluateRequest();
auto subtractCall = request.getExpression().initCall();
subtractCall.setFunction(subtract);
auto subtractParams = subtractCall.initParams(2);
subtractParams[1].setLiteral(67);
auto addCall = subtractParams[0].initCall();
addCall.setFunction(add);
auto addParams = addCall.initParams(2);
addParams[0].setLiteral(123);
addParams[1].setLiteral(45);
// Send the evaluate() request, read() the result, and wait for read() to
// finish.
auto evalPromise = request.send();
auto readPromise = evalPromise.getValue().readRequest().send();
auto response = readPromise.wait(waitScope);
KJ_ASSERT(response.getValue() == 101);
std::cout << "PASS" << std::endl;
}
{
// Make a request to evaluate 4 * 6, then use the result in two more
// requests that add 3 and 5.
//
// Since evaluate() returns its result wrapped in a `Value`, we can pass
// that `Value` back to the server in subsequent requests before the first
// `evaluate()` has actually returned. Thus, this example again does only
// one network round trip.
std::cout << "Pipelining eval() calls... ";
std::cout.flush();
Calculator::Function::Client add = nullptr;
Calculator::Function::Client multiply = nullptr;
{
// Get the "add" function from the server.
auto request = calculator.getOperatorRequest();
request.setOp(Calculator::Operator::ADD);
add = request.send().getFunc();
}
{
// Get the "multiply" function from the server.
auto request = calculator.getOperatorRequest();
request.setOp(Calculator::Operator::MULTIPLY);
multiply = request.send().getFunc();
}
// Build the request to evaluate 4 * 6
auto request = calculator.evaluateRequest();
auto multiplyCall = request.getExpression().initCall();
multiplyCall.setFunction(multiply);
auto multiplyParams = multiplyCall.initParams(2);
multiplyParams[0].setLiteral(4);
multiplyParams[1].setLiteral(6);
auto multiplyResult = request.send().getValue();
// Use the result in two calls that add 3 and add 5.
auto add3Request = calculator.evaluateRequest();
auto add3Call = add3Request.getExpression().initCall();
add3Call.setFunction(add);
auto add3Params = add3Call.initParams(2);
add3Params[0].setPreviousResult(multiplyResult);
add3Params[1].setLiteral(3);
auto add3Promise = add3Request.send().getValue().readRequest().send();
auto add5Request = calculator.evaluateRequest();
auto add5Call = add5Request.getExpression().initCall();
add5Call.setFunction(add);
auto add5Params = add5Call.initParams(2);
add5Params[0].setPreviousResult(multiplyResult);
add5Params[1].setLiteral(5);
auto add5Promise = add5Request.send().getValue().readRequest().send();
// Now wait for the results.
KJ_ASSERT(add3Promise.wait(waitScope).getValue() == 27);
KJ_ASSERT(add5Promise.wait(waitScope).getValue() == 29);
std::cout << "PASS" << std::endl;
}
{
// Our calculator interface supports defining functions. Here we use it
// to define two functions and then make calls to them as follows:
//
// f(x, y) = x * 100 + y
// g(x) = f(x, x + 1) * 2;
// f(12, 34)
// g(21)
//
// Once again, the whole thing takes only one network round trip.
std::cout << "Defining functions... ";
std::cout.flush();
Calculator::Function::Client add = nullptr;
Calculator::Function::Client multiply = nullptr;
Calculator::Function::Client f = nullptr;
Calculator::Function::Client g = nullptr;
{
// Get the "add" function from the server.
auto request = calculator.getOperatorRequest();
request.setOp(Calculator::Operator::ADD);
add = request.send().getFunc();
}
{
// Get the "multiply" function from the server.
auto request = calculator.getOperatorRequest();
request.setOp(Calculator::Operator::MULTIPLY);
multiply = request.send().getFunc();
}
{
// Define f.
auto request = calculator.defFunctionRequest();
request.setParamCount(2);
{
// Build the function body.
auto addCall = request.getBody().initCall();
addCall.setFunction(add);
auto addParams = addCall.initParams(2);
addParams[1].setParameter(1); // y
auto multiplyCall = addParams[0].initCall();
multiplyCall.setFunction(multiply);
auto multiplyParams = multiplyCall.initParams(2);
multiplyParams[0].setParameter(0); // x
multiplyParams[1].setLiteral(100);
}
f = request.send().getFunc();
}
{
// Define g.
auto request = calculator.defFunctionRequest();
request.setParamCount(1);
{
// Build the function body.
auto multiplyCall = request.getBody().initCall();
multiplyCall.setFunction(multiply);
auto multiplyParams = multiplyCall.initParams(2);
multiplyParams[1].setLiteral(2);
auto fCall = multiplyParams[0].initCall();
fCall.setFunction(f);
auto fParams = fCall.initParams(2);
fParams[0].setParameter(0);
auto addCall = fParams[1].initCall();
addCall.setFunction(add);
auto addParams = addCall.initParams(2);
addParams[0].setParameter(0);
addParams[1].setLiteral(1);
}
g = request.send().getFunc();
}
// OK, we've defined all our functions. Now create our eval requests.
// f(12, 34)
auto fEvalRequest = calculator.evaluateRequest();
auto fCall = fEvalRequest.initExpression().initCall();
fCall.setFunction(f);
auto fParams = fCall.initParams(2);
fParams[0].setLiteral(12);
fParams[1].setLiteral(34);
auto fEvalPromise = fEvalRequest.send().getValue().readRequest().send();
// g(21)
auto gEvalRequest = calculator.evaluateRequest();
auto gCall = gEvalRequest.initExpression().initCall();
gCall.setFunction(g);
gCall.initParams(1)[0].setLiteral(21);
auto gEvalPromise = gEvalRequest.send().getValue().readRequest().send();
// Wait for the results.
KJ_ASSERT(fEvalPromise.wait(waitScope).getValue() == 1234);
KJ_ASSERT(gEvalPromise.wait(waitScope).getValue() == 4244);
std::cout << "PASS" << std::endl;
}
{
// Make a request that will call back to a function defined locally.
//
// Specifically, we will compute 2^(4 + 5). However, exponent is not
// defined by the Calculator server. So, we'll implement the Function
// interface locally and pass it to the server for it to use when
// evaluating the expression.
//
// This example requires two network round trips to complete, because the
// server calls back to the client once before finishing. In this
// particular case, this could potentially be optimized by using a tail
// call on the server side -- see CallContext::tailCall(). However, to
// keep the example simpler, we haven't implemented this optimization in
// the sample server.
std::cout << "Using a callback... ";
std::cout.flush();
Calculator::Function::Client add = nullptr;
{
// Get the "add" function from the server.
auto request = calculator.getOperatorRequest();
request.setOp(Calculator::Operator::ADD);
add = request.send().getFunc();
}
// Build the eval request for 2^(4+5).
auto request = calculator.evaluateRequest();
auto powCall = request.getExpression().initCall();
powCall.setFunction(kj::heap<PowerFunction>());
auto powParams = powCall.initParams(2);
powParams[0].setLiteral(2);
auto addCall = powParams[1].initCall();
addCall.setFunction(add);
auto addParams = addCall.initParams(2);
addParams[0].setLiteral(4);
addParams[1].setLiteral(5);
// Send the request and wait.
auto response = request.send().getValue().readRequest()
.send().wait(waitScope);
KJ_ASSERT(response.getValue() == 512);
std::cout << "PASS" << std::endl;
}
return 0;
}