comparison src/capnproto-0.6.0/c++/samples/calculator-client.c++ @ 147:45360b968bf4

Cap'n Proto v0.6 + build for OSX

+// 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;
+}