fix: use random id for proving jobs

yarn-project/prover-client/src/prover-pool/memory-proving-queue.ts

@@ -22,6 +22,7 @@ import type {
   RootRollupInputs,
   RootRollupPublicInputs,
 } from '@aztec/circuits.js';
+import { randomBytes } from '@aztec/foundation/crypto';
 import { AbortedError, TimeoutError } from '@aztec/foundation/error';
 import { MemoryFifo } from '@aztec/foundation/fifo';
 import { createDebugLogger } from '@aztec/foundation/log';
@@ -38,12 +39,15 @@ type ProvingJobWithResolvers<T extends ProvingRequest = ProvingRequest> = {
 
 const MAX_RETRIES = 3;
 
+const defaultIdGenerator = () => randomBytes(4).toString('hex');
+
 export class MemoryProvingQueue implements CircuitProver, ProvingJobSource {
-  private jobId = 0;
   private log = createDebugLogger('aztec:prover-client:prover-pool:queue');
   private queue = new MemoryFifo<ProvingJobWithResolvers>();
   private jobsInProgress = new Map<string, ProvingJobWithResolvers>();
 
+  constructor(private generateId = defaultIdGenerator) {}
+
   async getProvingJob({ timeoutSec = 1 } = {}): Promise<ProvingJob<ProvingRequest> | undefined> {
     try {
       const job = await this.queue.get(timeoutSec);
@@ -119,7 +123,7 @@ export class MemoryProvingQueue implements CircuitProver, ProvingJobSource {
   ): Promise<ProvingRequestResult<T['type']>> {
     const { promise, resolve, reject } = promiseWithResolvers<ProvingRequestResult<T['type']>>();
     const item: ProvingJobWithResolvers<T> = {
-      id: String(this.jobId++),
+      id: this.generateId(),
       request,
       signal,
       promise,