/**
* Request tracking and cancellation system for MCP protocol
* Tracks in-flight requests and supports cancellation via $/cancelRequest
*/
import { createLogger } from "./logger.js";
const logger = createLogger("usql-mcp:request-tracker");
export interface TrackedRequest {
id: string | number;
abortController: AbortController;
startTime: number;
}
class RequestTracker {
private requests: Map<string | number, TrackedRequest> = new Map();
/**
* Start tracking a request
* Returns an AbortSignal that can be passed to async operations
*/
track(requestId: string | number): AbortSignal {
const abortController = new AbortController();
const request: TrackedRequest = {
id: requestId,
abortController,
startTime: Date.now(),
};
this.requests.set(requestId, request);
logger.debug("[request-tracker] Started tracking request", {
requestId,
activeRequests: this.requests.size,
});
return abortController.signal;
}
/**
* Stop tracking a request (call when request completes)
*/
untrack(requestId: string | number): void {
const deleted = this.requests.delete(requestId);
if (deleted) {
logger.debug("[request-tracker] Stopped tracking request", {
requestId,
activeRequests: this.requests.size,
});
}
}
/**
* Cancel a tracked request
*/
cancel(requestId: string | number): boolean {
const request = this.requests.get(requestId);
if (!request) {
logger.warn("[request-tracker] Cannot cancel, request not found", {
requestId,
});
return false;
}
logger.info("[request-tracker] Cancelling request", {
requestId,
elapsedMs: Date.now() - request.startTime,
});
request.abortController.abort();
this.requests.delete(requestId);
return true;
}
/**
* Get number of active requests
*/
getActiveCount(): number {
return this.requests.size;
}
/**
* Cancel all tracked requests
*/
cancelAll(): void {
const count = this.requests.size;
if (count > 0) {
logger.info("[request-tracker] Cancelling all requests", { count });
for (const request of this.requests.values()) {
request.abortController.abort();
}
this.requests.clear();
}
}
}
// Singleton instance
const tracker = new RequestTracker();
export function trackRequest(requestId: string | number): AbortSignal {
return tracker.track(requestId);
}
export function untrackRequest(requestId: string | number): void {
tracker.untrack(requestId);
}
export function cancelRequest(requestId: string | number): boolean {
return tracker.cancel(requestId);
}
export function getActiveRequestCount(): number {
return tracker.getActiveCount();
}
export function cancelAllRequests(): void {
tracker.cancelAll();
}
