As Sogou`s C++ server engine, Sogou C++ Workflow supports almost all back-end C++ online services of Sogou, including all search services, cloud input method，online advertisements, etc., handling more than 10 billion requests every day. This is an enterprise-level programming engine in light and elegant design which can satisfy most C++ back-end development requirements.
- To quickly build an HTTP server:
#include <stdio.h>
#include "workflow/WFHttpServer.h"
int main()
{
WFHttpServer server([](WFHttpTask *task) {
task->get_resp()->append_output_body("<html>Hello World!</html>");
});
if (server.start(8888) == 0) { // start server on port 8888
getchar(); // press "Enter" to end.
server.stop();
}
return 0;
}- As a multifunctional asynchronous client, it currently supports
HTTP,Redis,MySQLandKafkaprotocols. - To implement client/server on user-defined protocol and build your own RPC system.
- srpc is based on it and it is an independent open source project, which supports srpc, brpc and thrift protocols.
- To build asynchronous workflow; support common series and parallel structures, and also support any DAG structures.
- As a parallel computing tool. In addition to networking tasks, Sogou C++ Workflow also includes the scheduling of computing tasks. All types of tasks can be put into the same flow.
- As a asynchronous file IO tool in
Linuxsystem, with high performance exceeding any system call. Disk file IO is also a task. - To realize any high-performance and high-concurrency back-end service with a very complex relationship between computing and networking.
- To build a micro service system.
- This project has built-in service governance and load balancing features.
- This project supports
Linux,macOS,Windowsand other operating systems.Windowsversion is currently released as an independent branch, usingiocpto implement asynchronous networking. All user interfaces are consistent with theLinuxversion.
- Supports all CPU platforms, including 32 or 64-bit
x86processors, big-endian or little-endianarmprocessors. - Relies on
OpenSSL;OpenSSL 1.1and above is recommended. If you don't like SSL, you may checkout the nossl branch. But still need to linkcryptoformd5andsha1. - Uses the
C++11standard and therefore, it should be compiled with a compiler which supportsC++11. Does not rely onboostorasio. - No other dependencies. However, if you need
Kafkaprotocol, some compression libraries should be installed, includinglz4,zstdandsnappy.
- Client
- Server
- Parallel tasks and Series
- Important topics
- Computing tasks
- Asynchronous File IO tasks
- User-defined protocol
- Timing tasks and counting tasks
- Service governance
- Connection context
- Built-in protocols
We believe that a typical back-end program=protocol+algorithm+workflow and should be developed completely independently.
- Protocol
- In most cases, users use built-in common network protocols, such as HTTP, Redis or various rpc.
- Users can also easily customize user-defined network protocol. In the customization, they only need to provide serialization and deserialization functions to define their own client/server.
- Algorithm
- In our design, the algorithm is a concept symmetrical to the protocol.
- If protocol call is rpc, then algorithm call is an apc (Async Procedure Call).
- We have provided some general algorithms, such as sort, merge, psort, reduce, which can be used directly.
- Compared with a user-defined protocol, a user-defined algorithm is much more common. Any complicated computation with clear boundaries should be packaged into an algorithm.
- In our design, the algorithm is a concept symmetrical to the protocol.
- Workflow
- Workflow is the actual bussiness logic, which is to put the protocols and algorithms into the flow graph for use.
- The typical workflow is a closed series-parallel graph. Complex business logic may be a non-closed DAG.
- The workflow graph can be constructed directly or dynamically generated based on the results of each step. All tasks are executed asynchronously.
Basic task, task factory and complex task
- Our system contains six basic tasks: networking, file IO, CPU, GPU, timer, and counter.
- All tasks are generated by the task factory and automatically recycled after callback.
- Server task is one kind of special networking task, generated by the framework which calls the task factory, and handed over to the user through the process function.
- In most cases, the task generated by the user through the task factory is a complex task, which is transparent to the user.
- For example, an HTTP request may include many asynchronous processes (DNS, redirection), but for user, it is just a networking task.
- File sorting seems to be an algorithm, but it actually includes many complex interaction processes between file IO and CPU computation.
- If you think of business logic as building circuits with well-designed electronic components, then each electronic component may be a complex circuit.
Asynchrony and encapsulation based on C++11 std::function
- Not based on user mode coroutines. Users need to know that they are writing asynchronous programs.
- All calls are executed asynchronously, and there are almost no operation that occupys a thread.
- Although we also provide some facilities with semi-synchronous interfaces, they are not core features.
- We try to avoid user's derivations, and encapsulate user behavior with
std::functioninstead, including:- The callback of any task.
- Any server's process. This conforms to the
FaaS(Function as a Service) idea. - The realization of an algorithm is simply a
std::function. But the algorithm can also be implemented by derivation.
Memory reclamation mechanism
- Every task will be automatically reclaimed after the callback. If a task is created but a user does not want to run it, the user needs to release it through the dismiss method.
- Any data in the task, such as the response of the network request, will also be recycled with the task. At this time, the user can use
std::move()to move the required data. - SeriesWork and ParallelWork are two kinds of framework objects, which are also recycled after their callback.
- When a series is a branch of a parallel, it will be recycled after the callback of the parallel that it belongs to.
- This project doesn’t use
std::shared_ptrto manage memory.
To be continued...