Clean up and readme

Author: mezzode

.gitignore

@@ -11,4 +11,3 @@ CTestTestfile.cmake
 _deps
 .vs
 out
-CMakeSettings.json

CMakeLists.txt

@@ -1,9 +1,7 @@
-# CMakeList.txt : CMake project for StreamBase, include source and define
-# project specific logic here.
-#
+project(StreamBase)
 cmake_minimum_required (VERSION 3.8)
 
 # Add source to this project's executable.
-add_executable (server "server.cpp" "server.h")
-add_executable (exampleClient "exampleClient.cpp" "CustomClass.cpp" "CustomClass.h" "client.cpp" "client.h")
-add_executable (exampleAsyncClient "exampleAsyncClient.cpp" "CustomClass.cpp" "CustomClass.h" "client.cpp" "client.h")
+add_executable (server "server.cpp" "server.h" "common.cpp" "common.h")
+add_executable (exampleClient "exampleClient.cpp" "CustomClass.cpp" "CustomClass.h" "client.cpp" "client.h" "common.cpp" "common.h")
+add_executable (exampleAsyncClient "exampleAsyncClient.cpp" "CustomClass.cpp" "CustomClass.h" "client.cpp" "client.h" "common.cpp" "common.h")

CMakeSettings.json

@@ -0,0 +1,28 @@
+{
+  "configurations": [
+    {
+      "name": "x64-Debug",
+      "generator": "Ninja",
+      "configurationType": "Debug",
+      "inheritEnvironments": [ "msvc_x64_x64" ],
+      "buildRoot": "${projectDir}\\out\\build\\${name}",
+      "installRoot": "${projectDir}\\out\\install\\${name}",
+      "cmakeCommandArgs": "",
+      "buildCommandArgs": "-v",
+      "ctestCommandArgs": "",
+      "variables": []
+    },
+    {
+      "name": "x64-Release",
+      "generator": "Ninja",
+      "configurationType": "Release",
+      "buildRoot": "${projectDir}\\out\\build\\${name}",
+      "installRoot": "${projectDir}\\out\\install\\${name}",
+      "cmakeCommandArgs": "",
+      "buildCommandArgs": "-v",
+      "ctestCommandArgs": "",
+      "inheritEnvironments": [ "msvc_x64_x64" ],
+      "variables": []
+    }
+  ]
+}

README.md

@@ -1 +1,32 @@
-StreamBase
+# StreamBase
+
+Clients communicate with the server by initially sending a header message containing an Action which specifies whether they want to do a save or a get and what key to use.
+
+## Send
+On receiving a send action, the server will expect and read a second message containing the binary archive of the data.
+After inserting the data into the store, the server will send a message back to the client notifying it the save has been completed.
+
+## Get
+On receiving a get action, the server will retrieve the binary archive for the given key from the store and send it back in a message to the client.
+Note that the client-side `get()` function requires the type of the data being returned to be specified.
+
+## Data Store
+The server stores data in a map from the given key to a binary archive of the provided object.
+The map is guarded by a shared mutex to ensure thread-safe access.
+
+## Serialization
+
+This implementation of StreamBase depends on `cereal` to serialize data.
+This means extra code may be required for certain types of data
+e.g. for custom classes a `serialize` method that is a `friend` of the class may be required in order to serialize its attributes, as C++ lacks reflection.
+
+## Assumptions
+
+For simplicity it is assumed data being sent fits within a single message, and that cases will conform to the spec meaning there is currently no error handling
+e.g. attempting to retrieve data which has not been saved is unhandled, clients expect the server to be running, etc.
+
+## Multithreading
+
+This implementation of StreamBase supports async via multithreading. The server uses a different thread and pipe instance for each client connection.
+
+Multithreaded code uses a custom `log()` function as `cout` is not thread-safe.

client.cpp

@@ -1,7 +1,4 @@
-// client.cpp : Defines the entry point for the application.
-//
-
-#include <windows.h>
+#include <windows.h>
 #include <sstream>
 #include <string>
 #include <vector>
@@ -12,11 +9,11 @@
 using namespace std;
 
 void sendHeader(HANDLE h, string key) {
-	cout << "Sending header." << endl;
+	log("Sending header.");
 
 	auto headerData{ serialize(Action { Type::Send, key }) };
 	DWORD bytesWritten{ 0 };
-	const BOOL success = WriteFile(
+	const bool success = WriteFile(
 		h,
 		&headerData[0],
 		headerData.size(),
@@ -27,14 +24,20 @@ void sendHeader(HANDLE h, string key) {
 	if (!success) {
 		throw GetLastError();
 	}
-	cout << "Sent header." << endl;
+	log("Sent header.");
 }
 
 bool awaitSendSuccess(HANDLE h) {
-	std::vector<char> buf(bufSize);
+	vector<char> buf(bufSize);
 
 	DWORD bytesRead;
-	const BOOL readSuccess = ReadFile(h, buf.data(), buf.size(), &bytesRead, nullptr); // Use ReadFileEx for async
+	const bool readSuccess = ReadFile(
+		h,
+		buf.data(),
+		buf.size(),
+		&bytesRead,
+		nullptr
+	);
 	if (!readSuccess) {
 		throw GetLastError();
 	}

client.h

@@ -1,12 +1,8 @@
-// client.h : Include file for standard system include files,
-// or project specific include files.
-
-#pragma once
+#pragma once
 
 #include <iostream>
 #include <string>
 #include <vector>
-#include <windows.h>
 #include "common.h"
 #include "serialization.h"
 
@@ -36,7 +32,8 @@ void send(string key, T data) {
 				throw "Couldn't connect.";
 			}
 
-			// else server hasnt yet made another instance for additional clients so wait
+			// server hasnt yet made another instance for additional clients
+			// so wait then try again
 			auto instanceReady{ WaitNamedPipe(pipeName, NMPWAIT_WAIT_FOREVER) };
 			if (!instanceReady) {
 				cout << "Couldn't connect: 0x" << hex << GetLastError() << endl;
@@ -45,8 +42,6 @@ void send(string key, T data) {
 		}
 	}
 
-	cout << "CreateFile " << key << endl;
-
 	DWORD mode{ PIPE_READMODE_MESSAGE };
 	auto modeSet = SetNamedPipeHandleState(
 		h,    // pipe handle 
@@ -57,23 +52,21 @@ void send(string key, T data) {
 		throw "Couldn't put pipe into message mode.";
 	}
 
-	cout << "Mode set " << key << endl;
-
 	sendHeader(h, key);
 	sendData(h, data);
 	const bool success = awaitSendSuccess(h);
 
 	CloseHandle(h);
-	cout << "Send " << (success ? "success" : "fail") << endl;
+	log(string{ "Send " } + (success ? "success" : "fail"));
 }
 
 template<class T>
 T get(string key) {
-	cout << "Getting data for key " << key << endl;
+	log("Getting data for key " + key);
 	auto headerData{ serialize(Action { Type::Get, key }) };
-	std::vector<char> buf(bufSize);
+	vector<char> buf(bufSize);
 	DWORD bytesRead;
-	const BOOL success = CallNamedPipe(
+	const bool success = CallNamedPipe(
 		pipeName,
 		&headerData[0],
 		headerData.size(),
@@ -85,18 +78,18 @@ T get(string key) {
 	if (!success) {
 		throw GetLastError();
 	}
-	cout << "Got data for key " << key << endl;
+	log("Got data for key " + key);
 	auto data{ deserialize<T>(string{buf.data(), bytesRead}) };
 	return data;
 }
 
 template<class T>
 void sendData(HANDLE h, T data) {
-	cout << "Sending data." << endl;
+	log("Sending data");
 	auto writeStr{ serialize(data) };
 
 	DWORD bytesWritten{ 0 };
-	const BOOL success = WriteFile(
+	const bool success = WriteFile(
 		h,
 		&writeStr[0],
 		writeStr.size(),
@@ -105,8 +98,8 @@ void sendData(HANDLE h, T data) {
 	);
 
 	if (!success) {
-		// throw GetLastError();
 		cout << "0x" << hex << GetLastError() << endl;
+		throw GetLastError();
 	}
-	cout << "Sent data." << endl;
+	log("Sent data");
 }

common.cpp

@@ -0,0 +1,10 @@
+#include <iostream>
+#include <mutex>
+#include "common.h"
+
+std::mutex coutLock;
+
+void log(std::string msg) {
+	std::lock_guard<std::mutex> lg{ coutLock };
+	std::cout << msg << std::endl;
+}

common.h

@@ -1,6 +1,9 @@
 #pragma once
 
 #include <string>
+#include <windows.h>
+
+void log(std::string msg);
 
 constexpr LPCSTR pipeName{ R"(\\.\pipe\StreamBase)" };
 constexpr DWORD bufSize{ 512 };

exampleAsyncClient.cpp

@@ -7,55 +7,75 @@ using namespace std;
 
 int main()
 {
-	cout << "I am the async client." << endl;
+	log("I am the async client.");
 
-	const auto policy{ std::launch::async };
+	const auto policy{ launch::async };
+
+	const string intKey{ "MyKeyAsync" };
+	const string strKey{ "She" };
+	const string customKey{ "CustomClassAsync" };
 
 	// sends
 
-	auto intSend{ std::async(policy, []() {
-		cout << "Sending int" << endl;
-		send("mykeyasync", 101);
+	auto intSend{ async(policy, [intKey]() {
+		log("Sending int");
+		try {
+			send(intKey, 101);
+		}
+		catch (char e[]) {
+			// manually catch errors since exceptions only propagate on .get()
+			log(e);
+			terminate();
+		}
+		log("Sent int");
 	}) };
 
-	auto strSend{ std::async(policy, []() {
-		cout << "Sending string" << endl;
+	auto strSend{ async(policy, [strKey]() {
+		log("Sending string");
 		try {
-			send("she", string{ "ra" });
+			send(strKey, string{ "Ra" });
 		} catch (char e[]) {
 			// manually catch errors since exceptions only propagate on .get()
-			cout << e << endl;
-			std::terminate();
+			log(e);
+			terminate();
 		}
-		cout << "Sent string" << endl;
+		log("Sent string");
 	}) };
 
-	auto customSend{ std::async(policy, []() {
-		cout << "Sending custom class" << endl;
+	auto customSend{ async(policy, [customKey]() {
+		log("Sending custom class");
 		CustomClass custom{ 42, 81 };
 		custom.incrementA();
 		custom.incrementB();
-		send("mycustomclassasync", custom);
+		try {
+			send(customKey, custom);
+		}
+		catch (char e[]) {
+			// manually catch errors since exceptions only propagate on .get()
+			log(e);
+			terminate();
+		}
+		log("Sent custom class");
 	}) };
 
 	// gets
 
-	auto intGet{ std::async(policy, [&intSend]() {
+	auto intGet{ async(policy, [intKey, &intSend]() {
 		intSend.get(); // await send success
-		cout << get<int>("mykeyasync") << endl;
+		log(intKey + " -> " + to_string(get<int>(intKey)));
 	}) };
 
-	auto strGet{ std::async(policy, [&strSend]() {
+	auto strGet{ async(policy, [strKey, &strSend]() {
 		strSend.get(); // await send success
-		cout << get<string>("she") << endl;
+		log(strKey + " -> " + get<string>(strKey));
 	}) };
 
-	auto customGet{ std::async(policy, [&customSend]() {
+	auto customGet{ async(policy, [customKey, &customSend]() {
 		customSend.get(); // await send success
-		auto savedCustom{ get<CustomClass>("mycustomclassasync") };
+		auto savedCustom{ get<CustomClass>(customKey) };
 		savedCustom.incrementA();
 		savedCustom.incrementB();
-		cout << savedCustom.getA() << endl << savedCustom.getB() << endl;
+		log("A=" + to_string(savedCustom.getA()) + ", B=" + to_string(savedCustom.getB()));
 	}) };
 
 	getchar(); // wait before closing

serialization.h

@@ -1,7 +1,7 @@
 #pragma once
 
 #include <string>
-#include "cereal/archives/binary.hpp" // assuming we can use appropriate 3rd party libs
+#include "cereal/archives/binary.hpp"
 #include "cereal/types/string.hpp"
 
 template<class T>
@@ -12,7 +12,6 @@ std::string serialize(T data) {
 		cereal::BinaryOutputArchive oarchive{ out };
 		oarchive(data);
 	}
-	// writeStr.c_str() returns a const char * so would need to copy it to get a non-const *
 	return out.str();
 }
 
@@ -24,6 +23,5 @@ T deserialize(const std::string& serializedData) {
 		cereal::BinaryInputArchive iarchive{ in };
 		iarchive(data);
 	}
-	// writeStr.c_str() returns a const char * so would need to copy it to get a non-const *
 	return data;
 }