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|
/**
* McpManager — one McpClient per configured server; lazy-spawn on first
* tool access; status(servers); getClient(serverId); shutdownAll().
*
* Mirrors the LSP manager lifecycle. Injected spawn + logger (no I/O of its
* own: config resolution happens in the extension layer; the manager receives
* already-resolved servers).
*/
import { McpClient } from "./client.js";
import type { Connection, SpawnProcess } from "./transport.js";
import type { McpServerState, McpServerStatus, ResolvedMcpServer } from "./types.js";
export interface Logger {
readonly info: (msg: string, attrs?: Record<string, string | number | boolean | null>) => void;
readonly warn: (msg: string, attrs?: Record<string, string | number | boolean | null>) => void;
readonly error: (msg: string, attrs?: Record<string, unknown>) => void;
}
export interface McpManagerDeps {
readonly spawn: SpawnProcess;
readonly logger?: Logger;
readonly now?: () => number;
}
export type ConnectionFactory = (
server: ResolvedMcpServer,
cwd: string,
) => { connection: Connection; promise: Promise<void> };
type ClientEntry = {
readonly client: McpClient;
readonly server: ResolvedMcpServer;
readonly promise: Promise<void>;
};
type BrokenEntry = {
readonly brokenAt: number;
readonly error: string;
};
const BACKOFF_MS = 30_000;
export class McpManager {
private clients = new Map<string, ClientEntry>();
private broken = new Map<string, BrokenEntry>();
private spawning = new Map<string, Promise<void>>();
private readonly deps: McpManagerDeps;
private readonly connectionFactory: ConnectionFactory;
private readonly now: () => number;
constructor(deps: McpManagerDeps, connectionFactory: ConnectionFactory) {
this.deps = deps;
this.connectionFactory = connectionFactory;
this.now = deps.now ?? Date.now;
}
getClient(serverId: string): McpClient | undefined {
return this.clients.get(serverId)?.client;
}
getServerState(serverId: string): McpServerState {
const brokenEntry = this.broken.get(serverId);
if (brokenEntry) {
const backoffElapsed = this.now() - brokenEntry.brokenAt >= BACKOFF_MS;
if (backoffElapsed) {
this.broken.delete(serverId);
} else {
return "error";
}
}
const entry = this.clients.get(serverId);
if (!entry) return "disconnected";
const state = entry.client.getState();
if (state === "error") return "error";
if (state === "connecting") return "connecting";
if (state === "connected") return "connected";
return "disconnected";
}
status(servers: readonly ResolvedMcpServer[]): McpServerStatus[] {
const results: McpServerStatus[] = [];
for (const server of servers) {
const state = this.getServerState(server.id);
const entry = this.clients.get(server.id);
const brokenEntry = this.broken.get(server.id);
const status: McpServerStatus = {
id: server.id,
state,
toolCount: entry?.client.getTools().length ?? 0,
};
if (state === "error" && brokenEntry) {
(status as { error?: string }).error = brokenEntry.error;
} else if (state === "error" && entry?.client.getState() === "error") {
(status as { error?: string }).error = brokenEntry?.error ?? `${server.id}: client error`;
}
results.push(status);
}
return results;
}
async ensureConnected(server: ResolvedMcpServer, cwd: string): Promise<McpClient> {
const existing = this.clients.get(server.id);
if (existing && existing.client.getState() === "connected") {
return existing.client;
}
const brokenEntry = this.broken.get(server.id);
if (brokenEntry) {
const backoffElapsed = this.now() - brokenEntry.brokenAt >= BACKOFF_MS;
if (!backoffElapsed) {
throw new Error(brokenEntry.error);
}
this.broken.delete(server.id);
}
await this.spawnClient(server, cwd);
const entry = this.clients.get(server.id);
if (!entry) {
throw new Error(`Failed to spawn MCP client for ${server.id}`);
}
if (entry.client.getState() === "error") {
const brokenNow = this.broken.get(server.id);
throw new Error(brokenNow?.error ?? `${server.id}: client error`);
}
return entry.client;
}
private async spawnClient(server: ResolvedMcpServer, cwd: string): Promise<void> {
const existingSpawn = this.spawning.get(server.id);
if (existingSpawn) return existingSpawn;
const spawnPromise = this.doSpawn(server, cwd);
this.spawning.set(server.id, spawnPromise);
try {
await spawnPromise;
} finally {
this.spawning.delete(server.id);
}
}
private async doSpawn(server: ResolvedMcpServer, cwd: string): Promise<void> {
const { connection, promise } = this.connectionFactory(server, cwd);
const client = new McpClient({ connection });
const entry: ClientEntry = {
client,
server,
promise: this.initClient(client, server, promise),
};
this.clients.set(server.id, entry);
await entry.promise;
// If initialization failed, the client is in an error state and broken[]
// is already populated. Drop the half-created client (and reap its child
// process) so a later retry spawns fresh instead of returning a dead entry.
if (client.getState() === "error") {
this.clients.delete(server.id);
client.close();
}
}
private async initClient(
client: McpClient,
server: ResolvedMcpServer,
_transportPromise: Promise<void>,
): Promise<void> {
try {
await client.initialize();
await client.listTools();
this.deps.logger?.info("MCP server connected", {
serverId: server.id,
toolCount: String(client.getTools().length),
});
} catch (err: unknown) {
const message = err instanceof Error ? err.message : String(err);
this.broken.set(server.id, {
brokenAt: this.now(),
error: `${server.id}: ${message}`,
});
this.deps.logger?.warn("MCP server failed to connect", {
serverId: server.id,
error: message,
});
}
}
shutdownAll(): void {
for (const [, entry] of this.clients) {
entry.client.close();
}
this.clients.clear();
this.broken.clear();
this.spawning.clear();
this.deps.logger?.info("All MCP servers shut down");
}
}
|
