298 lines
9.9 KiB
JavaScript
298 lines
9.9 KiB
JavaScript
/**
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* Generic long-lived socket provider.
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*
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* Sub-classing notes
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* - a sub-class MUST call the `_start()` method once connected
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* - a sub-class MUST override the `_write(string)` method
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* - a sub-class MUST call `_processMessage(string)` for each message
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*
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* @_subsection: api/providers/abstract-provider:Socket Providers [about-socketProvider]
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*/
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import { UnmanagedSubscriber } from "./abstract-provider.js";
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import { assert, assertArgument, makeError } from "../utils/index.js";
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import { JsonRpcApiProvider } from "./provider-jsonrpc.js";
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/**
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* A **SocketSubscriber** uses a socket transport to handle events and
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* should use [[_emit]] to manage the events.
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*/
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export class SocketSubscriber {
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#provider;
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#filter;
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/**
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* The filter.
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*/
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get filter() { return JSON.parse(this.#filter); }
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#filterId;
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#paused;
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#emitPromise;
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/**
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* Creates a new **SocketSubscriber** attached to %%provider%% listening
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* to %%filter%%.
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*/
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constructor(provider, filter) {
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this.#provider = provider;
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this.#filter = JSON.stringify(filter);
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this.#filterId = null;
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this.#paused = null;
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this.#emitPromise = null;
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}
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start() {
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this.#filterId = this.#provider.send("eth_subscribe", this.filter).then((filterId) => {
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;
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this.#provider._register(filterId, this);
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return filterId;
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});
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}
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stop() {
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(this.#filterId).then((filterId) => {
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this.#provider.send("eth_unsubscribe", [filterId]);
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});
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this.#filterId = null;
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}
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// @TODO: pause should trap the current blockNumber, unsub, and on resume use getLogs
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// and resume
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pause(dropWhilePaused) {
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assert(dropWhilePaused, "preserve logs while paused not supported by SocketSubscriber yet", "UNSUPPORTED_OPERATION", { operation: "pause(false)" });
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this.#paused = !!dropWhilePaused;
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}
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resume() {
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this.#paused = null;
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}
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/**
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* @_ignore:
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*/
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_handleMessage(message) {
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if (this.#filterId == null) {
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return;
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}
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if (this.#paused === null) {
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let emitPromise = this.#emitPromise;
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if (emitPromise == null) {
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emitPromise = this._emit(this.#provider, message);
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}
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else {
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emitPromise = emitPromise.then(async () => {
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await this._emit(this.#provider, message);
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});
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}
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this.#emitPromise = emitPromise.then(() => {
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if (this.#emitPromise === emitPromise) {
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this.#emitPromise = null;
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}
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});
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}
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}
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/**
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* Sub-classes **must** override this to emit the events on the
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* provider.
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*/
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async _emit(provider, message) {
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throw new Error("sub-classes must implemente this; _emit");
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}
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}
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/**
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* A **SocketBlockSubscriber** listens for ``newHeads`` events and emits
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* ``"block"`` events.
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*/
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export class SocketBlockSubscriber extends SocketSubscriber {
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/**
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* @_ignore:
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*/
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constructor(provider) {
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super(provider, ["newHeads"]);
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}
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async _emit(provider, message) {
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provider.emit("block", parseInt(message.number));
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}
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}
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/**
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* A **SocketPendingSubscriber** listens for pending transacitons and emits
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* ``"pending"`` events.
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*/
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export class SocketPendingSubscriber extends SocketSubscriber {
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/**
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* @_ignore:
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*/
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constructor(provider) {
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super(provider, ["newPendingTransactions"]);
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}
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async _emit(provider, message) {
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provider.emit("pending", message);
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}
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}
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/**
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* A **SocketEventSubscriber** listens for event logs.
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*/
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export class SocketEventSubscriber extends SocketSubscriber {
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#logFilter;
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/**
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* The filter.
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*/
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get logFilter() { return JSON.parse(this.#logFilter); }
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/**
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* @_ignore:
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*/
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constructor(provider, filter) {
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super(provider, ["logs", filter]);
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this.#logFilter = JSON.stringify(filter);
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}
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async _emit(provider, message) {
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provider.emit(this.logFilter, provider._wrapLog(message, provider._network));
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}
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}
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/**
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* A **SocketProvider** is backed by a long-lived connection over a
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* socket, which can subscribe and receive real-time messages over
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* its communication channel.
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*/
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export class SocketProvider extends JsonRpcApiProvider {
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#callbacks;
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// Maps each filterId to its subscriber
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#subs;
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// If any events come in before a subscriber has finished
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// registering, queue them
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#pending;
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/**
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* Creates a new **SocketProvider** connected to %%network%%.
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*
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* If unspecified, the network will be discovered.
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*/
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constructor(network, _options) {
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// Copy the options
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const options = Object.assign({}, (_options != null) ? _options : {});
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// Support for batches is generally not supported for
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// connection-base providers; if this changes in the future
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// the _send should be updated to reflect this
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assertArgument(options.batchMaxCount == null || options.batchMaxCount === 1, "sockets-based providers do not support batches", "options.batchMaxCount", _options);
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options.batchMaxCount = 1;
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// Socket-based Providers (generally) cannot change their network,
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// since they have a long-lived connection; but let people override
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// this if they have just cause.
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if (options.staticNetwork == null) {
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options.staticNetwork = true;
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}
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super(network, options);
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this.#callbacks = new Map();
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this.#subs = new Map();
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this.#pending = new Map();
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}
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// This value is only valid after _start has been called
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/*
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get _network(): Network {
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if (this.#network == null) {
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throw new Error("this shouldn't happen");
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}
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return this.#network.clone();
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}
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*/
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_getSubscriber(sub) {
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switch (sub.type) {
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case "close":
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return new UnmanagedSubscriber("close");
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case "block":
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return new SocketBlockSubscriber(this);
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case "pending":
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return new SocketPendingSubscriber(this);
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case "event":
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return new SocketEventSubscriber(this, sub.filter);
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case "orphan":
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// Handled auto-matically within AbstractProvider
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// when the log.removed = true
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if (sub.filter.orphan === "drop-log") {
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return new UnmanagedSubscriber("drop-log");
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}
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}
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return super._getSubscriber(sub);
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}
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/**
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* Register a new subscriber. This is used internalled by Subscribers
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* and generally is unecessary unless extending capabilities.
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*/
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_register(filterId, subscriber) {
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this.#subs.set(filterId, subscriber);
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const pending = this.#pending.get(filterId);
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if (pending) {
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for (const message of pending) {
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subscriber._handleMessage(message);
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}
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this.#pending.delete(filterId);
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}
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}
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async _send(payload) {
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// WebSocket provider doesn't accept batches
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assertArgument(!Array.isArray(payload), "WebSocket does not support batch send", "payload", payload);
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// @TODO: stringify payloads here and store to prevent mutations
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// Prepare a promise to respond to
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const promise = new Promise((resolve, reject) => {
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this.#callbacks.set(payload.id, { payload, resolve, reject });
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});
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// Wait until the socket is connected before writing to it
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await this._waitUntilReady();
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// Write the request to the socket
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await this._write(JSON.stringify(payload));
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return [await promise];
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}
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// Sub-classes must call this once they are connected
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/*
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async _start(): Promise<void> {
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if (this.#ready) { return; }
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for (const { payload } of this.#callbacks.values()) {
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await this._write(JSON.stringify(payload));
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}
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this.#ready = (async function() {
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await super._start();
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})();
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}
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*/
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/**
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* Sub-classes **must** call this with messages received over their
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* transport to be processed and dispatched.
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*/
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async _processMessage(message) {
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const result = (JSON.parse(message));
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if (result && typeof (result) === "object" && "id" in result) {
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const callback = this.#callbacks.get(result.id);
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if (callback == null) {
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this.emit("error", makeError("received result for unknown id", "UNKNOWN_ERROR", {
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reasonCode: "UNKNOWN_ID",
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result
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}));
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return;
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}
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this.#callbacks.delete(result.id);
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callback.resolve(result);
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}
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else if (result && result.method === "eth_subscription") {
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const filterId = result.params.subscription;
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const subscriber = this.#subs.get(filterId);
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if (subscriber) {
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subscriber._handleMessage(result.params.result);
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}
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else {
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let pending = this.#pending.get(filterId);
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if (pending == null) {
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pending = [];
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this.#pending.set(filterId, pending);
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}
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pending.push(result.params.result);
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}
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}
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else {
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this.emit("error", makeError("received unexpected message", "UNKNOWN_ERROR", {
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reasonCode: "UNEXPECTED_MESSAGE",
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result
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}));
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return;
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}
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}
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/**
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* Sub-classes **must** override this to send %%message%% over their
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* transport.
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*/
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async _write(message) {
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throw new Error("sub-classes must override this");
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}
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}
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//# sourceMappingURL=provider-socket.js.map
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