protomux-rpc-web/src/index.ts

297 lines
6.5 KiB
TypeScript

import EventEmitter from "events";
// @ts-ignore
import Protomux from "protomux";
// @ts-ignore
import c from "compact-encoding";
// @ts-ignore
import bitfield from "compact-encoding-bitfield";
// @ts-ignore
import bits from "bits-to-bytes";
import * as buffer from "buffer";
export default class ProtomuxRPC extends EventEmitter {
private _id: number;
private _ending: boolean;
private _error?: Error;
private _responding: number;
private _requests: Map<any, any>;
private _defaultValueEncoding: any;
private _responders: Map<any, any>;
private _channel: any;
private _request: any;
private _response: any;
constructor(stream: any, options: any = {}) {
super();
this._mux = Protomux.from(stream);
this._defaultValueEncoding = options?.valueEncoding;
this._id = 1;
this._ending = false;
this._responding = 0;
this._requests = new Map<any, any>();
this._responders = new Map<any, any>();
this._ready = this._init(options);
}
private _mux: any;
get mux() {
return this._mux;
}
private _ready;
get ready() {
return this._ready;
}
get closed() {
return this._channel.closed;
}
get stream() {
return this._mux.stream;
}
private async _init(options: any) {
this._channel = await this._mux.createChannel({
protocol: "protomux-rpc",
id: options?.id,
handshake: options?.handshake
? options?.handshakeEncoding || c.raw
: null,
onopen: this._onopen.bind(this),
onclose: this._onclose.bind(this),
ondestroy: this._ondestroy.bind(this),
});
if (this._channel === null) throw new Error("duplicate channel");
this._request = await this._channel.addMessage({
encoding: request,
onmessage: this._onrequest.bind(this),
});
this._response = await this._channel.addMessage({
encoding: response,
onmessage: this._onresponse.bind(this),
});
this._channel.open(options?.handshake);
await this._channel.ready;
}
_onopen(handshake: any) {
this.emit("open", handshake);
}
_onclose() {
const err = this._error || new Error("channel closed");
for (const request of this._requests.values()) {
request.reject(err);
}
this._requests.clear();
this._responders.clear();
this.emit("close");
}
_ondestroy() {
this.emit("destroy");
}
async _onrequest({
id,
method,
value,
}: {
id: number;
method: string;
value: any;
}) {
let error = null;
const responder = this._responders.get(method);
if (responder === undefined) error = `unknown method '${method}'`;
else {
const {
valueEncoding = this._defaultValueEncoding,
requestEncoding = valueEncoding,
responseEncoding = valueEncoding,
} = responder.options;
if (requestEncoding) value = c.decode(requestEncoding, value);
this._responding++;
try {
value = await responder.handler(value);
} catch (err: any) {
error = (err as Error).message;
}
this._responding--;
if (!error && responseEncoding && id) {
value = c.encode(responseEncoding, value);
}
}
if (id) this._response.send({ id, error, value });
this._endMaybe();
}
_onresponse({ id, error, value }: { id: number; error: string; value: any }) {
if (id === 0) return;
const request = this._requests.get(id);
if (request === undefined) return;
this._requests.delete(id);
if (error) request.reject(new Error(error));
else {
const {
valueEncoding = this._defaultValueEncoding,
responseEncoding = valueEncoding,
} = request.options;
if (responseEncoding) value = c.decode(responseEncoding, value);
request.resolve(value);
}
this._endMaybe();
}
respond(method: string, options: Function | any, handler: Function) {
if (typeof options === "function") {
handler = options;
options = {};
}
this._responders.set(method, { options, handler });
return this;
}
unrespond(method: string) {
this._responders.delete(method);
return this;
}
async request(method: string, value: any, options: any = {}) {
if (this.closed) throw new Error("channel closed");
const {
valueEncoding = this._defaultValueEncoding,
requestEncoding = valueEncoding,
} = options;
if (requestEncoding) value = c.encode(requestEncoding, value);
const id = this._id++;
this._request.send({ id, method, value });
return new Promise((resolve, reject) => {
this._requests.set(id, { options, resolve, reject });
});
}
event(method: string, value: any, options: any = {}) {
if (this.closed) throw new Error("channel closed");
const {
valueEncoding = this._defaultValueEncoding,
requestEncoding = valueEncoding,
} = options;
if (requestEncoding) value = c.encode(requestEncoding, value);
this._request.send({ id: 0, method, value });
}
cork() {
this._channel.cork();
}
uncork() {
this._channel.uncork();
}
async end() {
this._ending = true;
this._endMaybe();
await EventEmitter.once(this, "close");
}
_endMaybe() {
if (this._ending && this._responding === 0 && this._requests.size === 0) {
this._channel.close();
}
}
destroy(err: Error) {
this._error = err || new Error("channel destroyed");
this._channel.close();
}
}
const request = {
preencode(state: Buffer, m: any) {
c.uint.preencode(state, m.id);
c.string.preencode(state, m.method);
c.raw.preencode(state, m.value);
},
encode(state: Buffer, m: any) {
c.uint.encode(state, m.id);
c.string.encode(state, m.method);
c.raw.encode(state, m.value);
},
decode(state: Buffer) {
return {
id: c.uint.decode(state),
method: c.string.decode(state),
value: c.raw.decode(state),
};
},
};
const flags = bitfield(1);
const response = {
preencode(state: Buffer, m: any) {
flags.preencode(state);
c.uint.preencode(state, m.id);
if (m.error) c.string.preencode(state, m.error);
else c.raw.preencode(state, m.value);
},
encode(state: Buffer, m: any) {
flags.encode(state, bits.of(m.error));
c.uint.encode(state, m.id);
if (m.error) c.string.encode(state, m.error);
else c.raw.encode(state, m.value);
},
decode(state: Buffer) {
const [error] = bits.iterator(flags.decode(state));
return {
id: c.uint.decode(state),
error: error ? c.string.decode(state) : null,
value: !error ? c.raw.decode(state) : null,
};
},
};