使用Python编写RPCServer

周末抽空研究了一下vscode中的lsp，lsp是基于rpc协议的，于是就尝试做了一个简单的RPCServer。

RPCServer的使用与Flask类似，如下:

from rpc_server import RpcServer

app = RpcServer()


@app.method('initialize')
def initialize(params) -> str:
    return "Hello"

if __name__ == '__main__':
    app.run(host='0.0.0.0', port=7788)

一、RPCServer

本文基于TCP长连接，采用多线程架构，即每一个RPC连接启用一个线程。

import os
import json
import socket
import threading
import warnings


class RpcServer:
    def __init__(self, encoding="utf8"):
        self.encoding = encoding

        self.socket = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
        self.methods = dict()

    def run(self, host, port):
        self.socket.bind((host, int(port)))
        self.socket.listen()
        print(f"The server started, rpc://{host}:{port}.")

        while True:
            c, _ = self.socket.accept()
            threading.Thread(target=self.tcp_handler, args=(c,)).start()

    def tcp_handler(self, client: socket.socket):
        try:
            file = client.makefile("rwb")

            headers, body = dict(), None
            while True:
                line = file.readline().decode("ascii").strip()
                if len(line) > 0:
                    k, v = line.split(":")
                    headers[k.strip()] = v.strip()
                else:
                    key = "Content-Length"
                    if key not in headers:
                        warnings.warn("Content-Length is required.")
                        return

                    content_length = int(headers[key])
                    body = file.read(content_length).decode(self.encoding)
                    body = json.loads(body)

                    if "method" not in body or "params" not in body:
                        return

                    method, params = body["method"], body["params"]
                    if method not in self.methods:
                        warnings.warn(f"The specified method could not be found: {method}.")
                        continue

                    result = self.methods[method](params)

                    resp = {"id": body.get("id", "-1"), "jsonrpc": body.get("jsonrpc", "2.0"), "result": result}
                    buf = json.dumps(resp).encode("utf8")

                    file.write(f"Content-Length: {len(buf)}{os.sep}{os.sep}".encode("ascii"))
                    file.write(buf)
        except socket.error:
            pass

    def method(self, method):
        def wrapper(func):
            self.methods[method] = func
            return func

        return wrapper

二、VSCode

VSCode扩展配置ServerOptions的方式如下：

import * as path from 'path';
import { workspace, ExtensionContext } from 'vscode';
import * as net from "net";

import {
	Event,
	LanguageClient,
	LanguageClientOptions,
	Message,
	MessageWriter,
	ServerOptions,
	TransportKind
} from 'vscode-languageclient/node';
import { Socket } from 'dgram';
import { Direction } from 'tty';

let client: LanguageClient;

export function activate(context: ExtensionContext) {
	// https://github.com/microsoft/vscode-languageserver-node/issues/662
	const serverOptions: ServerOptions = ()=>{
		const socket = net.connect({
			"host":"127.0.0.1",
			"port": 7788,
		});
        return Promise.resolve({writer: socket, reader: socket});
	};

	// Options to control the language client
	const clientOptions: LanguageClientOptions = {
		// Register the server for plain text documents
		documentSelector: [{ scheme: 'file', language: 'plaintext' }],
		synchronize: {
			// Notify the server about file changes to '.clientrc files contained in the workspace
			fileEvents: workspace.createFileSystemWatcher('**/.clientrc')
		}
	};

	// Create the language client and start the client.
	client = new LanguageClient(
		'languageServerExample',
		'Language Server Example',
		serverOptions,
		clientOptions
	);

	// Start the client. This will also launch the server
	client.start();
}

export function deactivate(): Thenable<void> | undefined {
	if (!client) {
		return undefined;
	}
	return client.stop();
}

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• 本文作者： killf
• 本文链接： http://www.killf.info/编程语言/Python/使用Python编写RPCServer/
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