wehub-resource-sync
120 lines
3.4 KiB
TypeScript
120 lines
3.4 KiB
TypeScript
/**
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* Session — State machine for one pool session
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*
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* Lifecycle:
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* active ──(429)──▶ cooldown ──(timeout)──▶ active
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* active ──(5xx)──▶ dead ──(pruned)──▶ removed
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* active ──(TTL)──▶ replaced with fresh session
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*
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* Each session tracks:
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* - Fingerprint (UA + headers for one browser identity)
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* - Request metrics (total, success, fail, inflight)
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* - Cooldown state (exponential backoff on rate limits)
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*/
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import { type Fingerprint, type SessionStatus } from "./types.ts";
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export class Session {
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readonly id: string;
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readonly fingerprint: Fingerprint;
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readonly createdAt: number;
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status: SessionStatus = "active";
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inflight = 0;
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totalRequests = 0;
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successfulRequests = 0;
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failedRequests = 0;
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consecutiveFails = 0;
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cooldownUntil = 0;
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lastUsedAt = 0;
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constructor(
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fingerprint: Fingerprint,
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private readonly cooldownBase: number,
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private readonly cooldownMax: number,
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private readonly cooldownJitter: number,
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) {
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this.id = `sess-${fingerprint.id}-${Date.now().toString(36)}-${Math.random().toString(36).slice(2, 8)}`;
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this.fingerprint = fingerprint;
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this.createdAt = Date.now();
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}
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/** Whether this session can accept requests right now */
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get isAvailable(): boolean {
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if (this.status === "dead") return false;
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if (this.status === "cooldown") {
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if (Date.now() >= this.cooldownUntil) {
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// Auto-recover from cooldown
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this.status = "active";
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this.consecutiveFails = 0;
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return true;
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}
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return false;
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}
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return true;
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}
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/** Mark a successful request */
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markSuccess(): void {
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this.successfulRequests++;
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this.consecutiveFails = 0;
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}
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/** Enter cooldown with exponential backoff */
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markCooldown(): void {
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this.consecutiveFails++;
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const base = Math.min(
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this.cooldownBase * Math.pow(2, this.consecutiveFails - 1),
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this.cooldownMax,
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);
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const jitter = Math.random() * this.cooldownJitter;
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this.cooldownUntil = Date.now() + base + jitter;
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this.status = "cooldown";
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}
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/** Mark session as dead (non-recoverable error) */
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markDead(): void {
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this.status = "dead";
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}
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/** Increment inflight counter and mark as used */
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acquire(): void {
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this.inflight++;
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this.totalRequests++;
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this.lastUsedAt = Date.now();
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}
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/** Decrement inflight counter */
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release(): void {
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this.inflight = Math.max(0, this.inflight - 1);
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}
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/** Milliseconds remaining in cooldown */
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get cooldownRemaining(): number {
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if (this.status !== "cooldown") return 0;
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return Math.max(0, this.cooldownUntil - Date.now());
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}
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/** Age in milliseconds */
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get age(): number {
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return Date.now() - this.createdAt;
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}
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/** Build headers for this session's fingerprint */
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buildHeaders(extra?: Record<string, string>): Record<string, string> {
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const headers: Record<string, string> = {
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"Content-Type": "application/json",
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Accept: "application/json, text/plain, */*",
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"Accept-Language": this.fingerprint.acceptLanguage ?? "en-US,en;q=0.9",
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"User-Agent": this.fingerprint.userAgent,
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...extra,
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};
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if (this.fingerprint.secChUa) {
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headers["Sec-CH-UA"] = this.fingerprint.secChUa;
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headers["Sec-CH-UA-Mobile"] = this.fingerprint.secChUaMobile ?? "?0";
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headers["Sec-CH-UA-Platform"] = this.fingerprint.secChUaPlatform ?? '"Windows"';
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}
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return headers;
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}
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}
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