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