cannam@48: // Copyright (c) 2013-2014 Sandstorm Development Group, Inc. and contributors
cannam@48: // Licensed under the MIT License:
cannam@48: //
cannam@48: // Permission is hereby granted, free of charge, to any person obtaining a copy
cannam@48: // of this software and associated documentation files (the "Software"), to deal
cannam@48: // in the Software without restriction, including without limitation the rights
cannam@48: // to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
cannam@48: // copies of the Software, and to permit persons to whom the Software is
cannam@48: // furnished to do so, subject to the following conditions:
cannam@48: //
cannam@48: // The above copyright notice and this permission notice shall be included in
cannam@48: // all copies or substantial portions of the Software.
cannam@48: //
cannam@48: // THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
cannam@48: // IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
cannam@48: // FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
cannam@48: // AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
cannam@48: // LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
cannam@48: // OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
cannam@48: // THE SOFTWARE.
cannam@48: 
cannam@48: #include "calculator.capnp.h"
cannam@48: #include <capnp/ez-rpc.h>
cannam@48: #include <kj/debug.h>
cannam@48: #include <math.h>
cannam@48: #include <iostream>
cannam@48: 
cannam@48: class PowerFunction final: public Calculator::Function::Server {
cannam@48:   // An implementation of the Function interface wrapping pow().  Note that
cannam@48:   // we're implementing this on the client side and will pass a reference to
cannam@48:   // the server.  The server will then be able to make calls back to the client.
cannam@48: 
cannam@48: public:
cannam@48:   kj::Promise<void> call(CallContext context) {
cannam@48:     auto params = context.getParams().getParams();
cannam@48:     KJ_REQUIRE(params.size() == 2, "Wrong number of parameters.");
cannam@48:     context.getResults().setValue(pow(params[0], params[1]));
cannam@48:     return kj::READY_NOW;
cannam@48:   }
cannam@48: };
cannam@48: 
cannam@48: int main(int argc, const char* argv[]) {
cannam@48:   if (argc != 2) {
cannam@48:     std::cerr << "usage: " << argv[0] << " HOST:PORT\n"
cannam@48:         "Connects to the Calculator server at the given address and "
cannam@48:         "does some RPCs." << std::endl;
cannam@48:     return 1;
cannam@48:   }
cannam@48: 
cannam@48:   capnp::EzRpcClient client(argv[1]);
cannam@48:   Calculator::Client calculator = client.getMain<Calculator>();
cannam@48: 
cannam@48:   // Keep an eye on `waitScope`.  Whenever you see it used is a place where we
cannam@48:   // stop and wait for the server to respond.  If a line of code does not use
cannam@48:   // `waitScope`, then it does not block!
cannam@48:   auto& waitScope = client.getWaitScope();
cannam@48: 
cannam@48:   {
cannam@48:     // Make a request that just evaluates the literal value 123.
cannam@48:     //
cannam@48:     // What's interesting here is that evaluate() returns a "Value", which is
cannam@48:     // another interface and therefore points back to an object living on the
cannam@48:     // server.  We then have to call read() on that object to read it.
cannam@48:     // However, even though we are making two RPC's, this block executes in
cannam@48:     // *one* network round trip because of promise pipelining:  we do not wait
cannam@48:     // for the first call to complete before we send the second call to the
cannam@48:     // server.
cannam@48: 
cannam@48:     std::cout << "Evaluating a literal... ";
cannam@48:     std::cout.flush();
cannam@48: 
cannam@48:     // Set up the request.
cannam@48:     auto request = calculator.evaluateRequest();
cannam@48:     request.getExpression().setLiteral(123);
cannam@48: 
cannam@48:     // Send it, which returns a promise for the result (without blocking).
cannam@48:     auto evalPromise = request.send();
cannam@48: 
cannam@48:     // Using the promise, create a pipelined request to call read() on the
cannam@48:     // returned object, and then send that.
cannam@48:     auto readPromise = evalPromise.getValue().readRequest().send();
cannam@48: 
cannam@48:     // Now that we've sent all the requests, wait for the response.  Until this
cannam@48:     // point, we haven't waited at all!
cannam@48:     auto response = readPromise.wait(waitScope);
cannam@48:     KJ_ASSERT(response.getValue() == 123);
cannam@48: 
cannam@48:     std::cout << "PASS" << std::endl;
cannam@48:   }
cannam@48: 
cannam@48:   {
cannam@48:     // Make a request to evaluate 123 + 45 - 67.
cannam@48:     //
cannam@48:     // The Calculator interface requires that we first call getOperator() to
cannam@48:     // get the addition and subtraction functions, then call evaluate() to use
cannam@48:     // them.  But, once again, we can get both functions, call evaluate(), and
cannam@48:     // then read() the result -- four RPCs -- in the time of *one* network
cannam@48:     // round trip, because of promise pipelining.
cannam@48: 
cannam@48:     std::cout << "Using add and subtract... ";
cannam@48:     std::cout.flush();
cannam@48: 
cannam@48:     Calculator::Function::Client add = nullptr;
cannam@48:     Calculator::Function::Client subtract = nullptr;
cannam@48: 
cannam@48:     {
cannam@48:       // Get the "add" function from the server.
cannam@48:       auto request = calculator.getOperatorRequest();
cannam@48:       request.setOp(Calculator::Operator::ADD);
cannam@48:       add = request.send().getFunc();
cannam@48:     }
cannam@48: 
cannam@48:     {
cannam@48:       // Get the "subtract" function from the server.
cannam@48:       auto request = calculator.getOperatorRequest();
cannam@48:       request.setOp(Calculator::Operator::SUBTRACT);
cannam@48:       subtract = request.send().getFunc();
cannam@48:     }
cannam@48: 
cannam@48:     // Build the request to evaluate 123 + 45 - 67.
cannam@48:     auto request = calculator.evaluateRequest();
cannam@48: 
cannam@48:     auto subtractCall = request.getExpression().initCall();
cannam@48:     subtractCall.setFunction(subtract);
cannam@48:     auto subtractParams = subtractCall.initParams(2);
cannam@48:     subtractParams[1].setLiteral(67);
cannam@48: 
cannam@48:     auto addCall = subtractParams[0].initCall();
cannam@48:     addCall.setFunction(add);
cannam@48:     auto addParams = addCall.initParams(2);
cannam@48:     addParams[0].setLiteral(123);
cannam@48:     addParams[1].setLiteral(45);
cannam@48: 
cannam@48:     // Send the evaluate() request, read() the result, and wait for read() to
cannam@48:     // finish.
cannam@48:     auto evalPromise = request.send();
cannam@48:     auto readPromise = evalPromise.getValue().readRequest().send();
cannam@48: 
cannam@48:     auto response = readPromise.wait(waitScope);
cannam@48:     KJ_ASSERT(response.getValue() == 101);
cannam@48: 
cannam@48:     std::cout << "PASS" << std::endl;
cannam@48:   }
cannam@48: 
cannam@48:   {
cannam@48:     // Make a request to evaluate 4 * 6, then use the result in two more
cannam@48:     // requests that add 3 and 5.
cannam@48:     //
cannam@48:     // Since evaluate() returns its result wrapped in a `Value`, we can pass
cannam@48:     // that `Value` back to the server in subsequent requests before the first
cannam@48:     // `evaluate()` has actually returned.  Thus, this example again does only
cannam@48:     // one network round trip.
cannam@48: 
cannam@48:     std::cout << "Pipelining eval() calls... ";
cannam@48:     std::cout.flush();
cannam@48: 
cannam@48:     Calculator::Function::Client add = nullptr;
cannam@48:     Calculator::Function::Client multiply = nullptr;
cannam@48: 
cannam@48:     {
cannam@48:       // Get the "add" function from the server.
cannam@48:       auto request = calculator.getOperatorRequest();
cannam@48:       request.setOp(Calculator::Operator::ADD);
cannam@48:       add = request.send().getFunc();
cannam@48:     }
cannam@48: 
cannam@48:     {
cannam@48:       // Get the "multiply" function from the server.
cannam@48:       auto request = calculator.getOperatorRequest();
cannam@48:       request.setOp(Calculator::Operator::MULTIPLY);
cannam@48:       multiply = request.send().getFunc();
cannam@48:     }
cannam@48: 
cannam@48:     // Build the request to evaluate 4 * 6
cannam@48:     auto request = calculator.evaluateRequest();
cannam@48: 
cannam@48:     auto multiplyCall = request.getExpression().initCall();
cannam@48:     multiplyCall.setFunction(multiply);
cannam@48:     auto multiplyParams = multiplyCall.initParams(2);
cannam@48:     multiplyParams[0].setLiteral(4);
cannam@48:     multiplyParams[1].setLiteral(6);
cannam@48: 
cannam@48:     auto multiplyResult = request.send().getValue();
cannam@48: 
cannam@48:     // Use the result in two calls that add 3 and add 5.
cannam@48: 
cannam@48:     auto add3Request = calculator.evaluateRequest();
cannam@48:     auto add3Call = add3Request.getExpression().initCall();
cannam@48:     add3Call.setFunction(add);
cannam@48:     auto add3Params = add3Call.initParams(2);
cannam@48:     add3Params[0].setPreviousResult(multiplyResult);
cannam@48:     add3Params[1].setLiteral(3);
cannam@48:     auto add3Promise = add3Request.send().getValue().readRequest().send();
cannam@48: 
cannam@48:     auto add5Request = calculator.evaluateRequest();
cannam@48:     auto add5Call = add5Request.getExpression().initCall();
cannam@48:     add5Call.setFunction(add);
cannam@48:     auto add5Params = add5Call.initParams(2);
cannam@48:     add5Params[0].setPreviousResult(multiplyResult);
cannam@48:     add5Params[1].setLiteral(5);
cannam@48:     auto add5Promise = add5Request.send().getValue().readRequest().send();
cannam@48: 
cannam@48:     // Now wait for the results.
cannam@48:     KJ_ASSERT(add3Promise.wait(waitScope).getValue() == 27);
cannam@48:     KJ_ASSERT(add5Promise.wait(waitScope).getValue() == 29);
cannam@48: 
cannam@48:     std::cout << "PASS" << std::endl;
cannam@48:   }
cannam@48: 
cannam@48:   {
cannam@48:     // Our calculator interface supports defining functions.  Here we use it
cannam@48:     // to define two functions and then make calls to them as follows:
cannam@48:     //
cannam@48:     //   f(x, y) = x * 100 + y
cannam@48:     //   g(x) = f(x, x + 1) * 2;
cannam@48:     //   f(12, 34)
cannam@48:     //   g(21)
cannam@48:     //
cannam@48:     // Once again, the whole thing takes only one network round trip.
cannam@48: 
cannam@48:     std::cout << "Defining functions... ";
cannam@48:     std::cout.flush();
cannam@48: 
cannam@48:     Calculator::Function::Client add = nullptr;
cannam@48:     Calculator::Function::Client multiply = nullptr;
cannam@48:     Calculator::Function::Client f = nullptr;
cannam@48:     Calculator::Function::Client g = nullptr;
cannam@48: 
cannam@48:     {
cannam@48:       // Get the "add" function from the server.
cannam@48:       auto request = calculator.getOperatorRequest();
cannam@48:       request.setOp(Calculator::Operator::ADD);
cannam@48:       add = request.send().getFunc();
cannam@48:     }
cannam@48: 
cannam@48:     {
cannam@48:       // Get the "multiply" function from the server.
cannam@48:       auto request = calculator.getOperatorRequest();
cannam@48:       request.setOp(Calculator::Operator::MULTIPLY);
cannam@48:       multiply = request.send().getFunc();
cannam@48:     }
cannam@48: 
cannam@48:     {
cannam@48:       // Define f.
cannam@48:       auto request = calculator.defFunctionRequest();
cannam@48:       request.setParamCount(2);
cannam@48: 
cannam@48:       {
cannam@48:         // Build the function body.
cannam@48:         auto addCall = request.getBody().initCall();
cannam@48:         addCall.setFunction(add);
cannam@48:         auto addParams = addCall.initParams(2);
cannam@48:         addParams[1].setParameter(1);  // y
cannam@48: 
cannam@48:         auto multiplyCall = addParams[0].initCall();
cannam@48:         multiplyCall.setFunction(multiply);
cannam@48:         auto multiplyParams = multiplyCall.initParams(2);
cannam@48:         multiplyParams[0].setParameter(0);  // x
cannam@48:         multiplyParams[1].setLiteral(100);
cannam@48:       }
cannam@48: 
cannam@48:       f = request.send().getFunc();
cannam@48:     }
cannam@48: 
cannam@48:     {
cannam@48:       // Define g.
cannam@48:       auto request = calculator.defFunctionRequest();
cannam@48:       request.setParamCount(1);
cannam@48: 
cannam@48:       {
cannam@48:         // Build the function body.
cannam@48:         auto multiplyCall = request.getBody().initCall();
cannam@48:         multiplyCall.setFunction(multiply);
cannam@48:         auto multiplyParams = multiplyCall.initParams(2);
cannam@48:         multiplyParams[1].setLiteral(2);
cannam@48: 
cannam@48:         auto fCall = multiplyParams[0].initCall();
cannam@48:         fCall.setFunction(f);
cannam@48:         auto fParams = fCall.initParams(2);
cannam@48:         fParams[0].setParameter(0);
cannam@48: 
cannam@48:         auto addCall = fParams[1].initCall();
cannam@48:         addCall.setFunction(add);
cannam@48:         auto addParams = addCall.initParams(2);
cannam@48:         addParams[0].setParameter(0);
cannam@48:         addParams[1].setLiteral(1);
cannam@48:       }
cannam@48: 
cannam@48:       g = request.send().getFunc();
cannam@48:     }
cannam@48: 
cannam@48:     // OK, we've defined all our functions.  Now create our eval requests.
cannam@48: 
cannam@48:     // f(12, 34)
cannam@48:     auto fEvalRequest = calculator.evaluateRequest();
cannam@48:     auto fCall = fEvalRequest.initExpression().initCall();
cannam@48:     fCall.setFunction(f);
cannam@48:     auto fParams = fCall.initParams(2);
cannam@48:     fParams[0].setLiteral(12);
cannam@48:     fParams[1].setLiteral(34);
cannam@48:     auto fEvalPromise = fEvalRequest.send().getValue().readRequest().send();
cannam@48: 
cannam@48:     // g(21)
cannam@48:     auto gEvalRequest = calculator.evaluateRequest();
cannam@48:     auto gCall = gEvalRequest.initExpression().initCall();
cannam@48:     gCall.setFunction(g);
cannam@48:     gCall.initParams(1)[0].setLiteral(21);
cannam@48:     auto gEvalPromise = gEvalRequest.send().getValue().readRequest().send();
cannam@48: 
cannam@48:     // Wait for the results.
cannam@48:     KJ_ASSERT(fEvalPromise.wait(waitScope).getValue() == 1234);
cannam@48:     KJ_ASSERT(gEvalPromise.wait(waitScope).getValue() == 4244);
cannam@48: 
cannam@48:     std::cout << "PASS" << std::endl;
cannam@48:   }
cannam@48: 
cannam@48:   {
cannam@48:     // Make a request that will call back to a function defined locally.
cannam@48:     //
cannam@48:     // Specifically, we will compute 2^(4 + 5).  However, exponent is not
cannam@48:     // defined by the Calculator server.  So, we'll implement the Function
cannam@48:     // interface locally and pass it to the server for it to use when
cannam@48:     // evaluating the expression.
cannam@48:     //
cannam@48:     // This example requires two network round trips to complete, because the
cannam@48:     // server calls back to the client once before finishing.  In this
cannam@48:     // particular case, this could potentially be optimized by using a tail
cannam@48:     // call on the server side -- see CallContext::tailCall().  However, to
cannam@48:     // keep the example simpler, we haven't implemented this optimization in
cannam@48:     // the sample server.
cannam@48: 
cannam@48:     std::cout << "Using a callback... ";
cannam@48:     std::cout.flush();
cannam@48: 
cannam@48:     Calculator::Function::Client add = nullptr;
cannam@48: 
cannam@48:     {
cannam@48:       // Get the "add" function from the server.
cannam@48:       auto request = calculator.getOperatorRequest();
cannam@48:       request.setOp(Calculator::Operator::ADD);
cannam@48:       add = request.send().getFunc();
cannam@48:     }
cannam@48: 
cannam@48:     // Build the eval request for 2^(4+5).
cannam@48:     auto request = calculator.evaluateRequest();
cannam@48: 
cannam@48:     auto powCall = request.getExpression().initCall();
cannam@48:     powCall.setFunction(kj::heap<PowerFunction>());
cannam@48:     auto powParams = powCall.initParams(2);
cannam@48:     powParams[0].setLiteral(2);
cannam@48: 
cannam@48:     auto addCall = powParams[1].initCall();
cannam@48:     addCall.setFunction(add);
cannam@48:     auto addParams = addCall.initParams(2);
cannam@48:     addParams[0].setLiteral(4);
cannam@48:     addParams[1].setLiteral(5);
cannam@48: 
cannam@48:     // Send the request and wait.
cannam@48:     auto response = request.send().getValue().readRequest()
cannam@48:                            .send().wait(waitScope);
cannam@48:     KJ_ASSERT(response.getValue() == 512);
cannam@48: 
cannam@48:     std::cout << "PASS" << std::endl;
cannam@48:   }
cannam@48: 
cannam@48:   return 0;
cannam@48: }