feat(operator): fire-and-forget mint sender with batch confirmation polling

[Huzaifa696]

Summary

Decouples sendTransaction latency from the sender loop for Mint/InitializeMint transactions. Instead of blocking until each tx confirms, the sender signs and sends immediately, stores the signature, and moves on. A dedicated poll task batches all in-flight signatures into a single getSignatureStatuses call per interval.

• Fire-and-forget send: Mint/InitializeMint only.
• Batched confirmation: dedicated tokio task wakes on Notify, accumulates one poll interval, resolves all N signatures in one RPC call. Confirmed-success is handled entirely in the poll task; only errors and timeouts wake the sender loop.
• Semaphore back-pressure: MAX_IN_FLIGHT = 1000 permits. select! recv arm guarded by available_permits() > 0; when exhausted, the processor channel backs up and the fetcher stops.
• AccountNotFound now permanent: previously retried 5× with backoff (~1.5 s wasted per JIT mint lookup).
• bench-tps setup: setup_deposit now initialises the Contra-side SPL mint upfront so the operator doesn't hit JIT init on the first deposit.

Files changed

File	Change
sender/types.rs	InFlightTx, InFlightQueue (Arc<Mutex<Vec>> + Notify), PollTaskResult
sender/transaction.rs	spawn_fire_and_store, fire_and_store, run_poll_task, poll_in_flight; branches in handle_transaction_submission
sender/mod.rs	Wires poll task; both exit paths stop poll task before drain_in_flight
sender/state.rs	semaphore: Arc<Semaphore> added to SenderState
rpc_util.rs	AccountNotFound → permanent error
bench-tps/	Contra-side mint init in setup; dedicated BENCH_CONTRA_RPC_URL env var

Tests

• spawn_fire_and_store: cap exhausted returns false, permit consumed on success
• run_poll_task: cancellation (idle + mid-sleep), closed result channel exit
• drain_in_flight: empty queue no-op, 30 s timeout
• InFlightQueue: push/drain roundtrip, capacity preserved across drain_all
• is_permanent_rpc_error: Method not Found and AccountNotFound exit immediately

Impact

Deposit TPS: ~9 -> ~500

Coverage Report

Component	Lines Hit	Lines Total	Coverage	Artifact
Core	7,103	8,411	84.4%	rust-unit-coverage-reports
Indexer	13,471	15,715	85.7%	rust-unit-coverage-reports
Gateway	952	1,076	88.5%	rust-unit-coverage-reports
Auth	541	596	90.8%	rust-unit-coverage-reports
Withdraw Program	-	-	-	-
Escrow Program	-	-	-	-
E2E Integration	7,909	11,473	68.9%	e2e-coverage-reports
Total	29,976	37,271	80.4%

Last updated: 2026-04-09 18:06:27 UTC by E2E Integration

[greptile-apps]

Greptile Summary

This PR introduces a fire-and-forget mint sender with a dedicated batch-confirmation poll task (run_poll_task), decoupling transaction send from confirmation polling to improve throughput. It also adds a graceful-shutdown drain loop (drain_in_flight) and pre-initialises Contra mints during the bench-tps setup phase to avoid JIT initialisation overhead.

• The comment at the cancellation-arm drain site incorrectly states "The poll task has already been cancelled" — poll_shutdown.cancel() is not called until after the loop exits, so the poll task races with drain_in_flight during shutdown.
• DepositArgs::contra_rpc_url is bound to env = \"BENCH_RPC_URL\", which is the same env var already used by BenchArgs::rpc_url (default 8899) and WithdrawArgs::rpc_url, but with a different default value (8898), creating a confusing inconsistency.

Confidence Score: 4/5

Safe to merge after fixing the poll-task cancellation ordering in the shutdown path and the BENCH_RPC_URL env-var collision.

Two P1 findings: the poll task is not cancelled before drain_in_flight runs (incorrect comment + real race), and the BENCH_RPC_URL env var is reused with conflicting defaults. Both are actionable fixes. The core fire-and-forget architecture is sound, idempotency is preserved, and the DB recovery path handles the shutdown edge case. Tests are comprehensive.

indexer/src/operator/sender/mod.rs (shutdown ordering), bench-tps/src/args.rs (env var naming)

Vulnerabilities

No security concerns identified. The fire-and-forget path reuses the existing idempotency memo check before any send, preventing double-mint on re-delivery. The InFlightQueue mutex prevents concurrent data corruption. No new auth boundaries, secrets, or user-controlled inputs are introduced.

Important Files Changed

Filename	Overview
indexer/src/operator/sender/mod.rs	New drain_in_flight graceful-shutdown helper and sender main loop restructured; contains an incorrect comment and a real race between drain_in_flight and the still-running poll task.
indexer/src/operator/sender/transaction.rs	Core fire-and-forget logic: fire_and_store, run_poll_task, poll_in_flight, and route_poll_results — logic is sound; multi-chunk RPC failure discards already-fetched statuses (acceptable, undocumented).
indexer/src/operator/sender/types.rs	New InFlightQueue (Arc-wrapped Mutex+Vec+Notify) and InFlightTx/PollTaskResult types — design is clean and thread-safe.
bench-tps/src/args.rs	New contra_rpc_url field added to DepositArgs but reuses BENCH_RPC_URL env var with a conflicting default value vs existing fields.
bench-tps/src/setup_deposit.rs	Adds Contra mint pre-initialisation step (task 6b) using new contra_rpc_url parameter — logic is straightforward.
indexer/src/operator/utils/rpc_util.rs	New tests for with_retry covering permanent errors (-32601, AccountNotFound) and backoff clamping — good coverage, no issues.
indexer/src/operator/utils/transaction_util.rs	New mockito-based tests for check_transaction_status and sign_and_send_transaction — comprehensive, no issues.
indexer/src/operator/sender/state.rs	Adds in_flight: InFlightQueue::new() to SenderState construction and test helpers; minor trailing blank line added before closing brace.

Sequence Diagram

sequenceDiagram
    participant P as Processor
    participant S as Sender Loop
    participant IFQ as InFlightQueue
    participant PT as Poll Task
    participant RPC as Solana RPC
    participant DB as Storage

    P->>S: TransactionBuilder (Mint/InitializeMint)
    S->>S: find_existing_mint_signature (idempotency)
    S->>S: handle_transaction_builder → InstructionWithSigners
    S->>RPC: sendTransaction (fire_and_store)
    RPC-->>S: Signature
    S->>IFQ: push(InFlightTx) + notify_one()

    loop Poll Task (dedicated task)
        IFQ-->>PT: notify.notified()
        PT->>PT: sleep(poll_interval_ms)
        PT->>IFQ: drain_all()
        PT->>RPC: getSignatureStatuses (batched, 256/call)
        RPC-->>PT: statuses[]
        alt Confirmed Success
            PT->>DB: TransactionStatusUpdate(Completed)
            PT->>S: PollTaskResult::ConfirmedSuccess(txn_id)
            S->>S: mint_builders.remove(txn_id)
        else On-chain Error / Timeout
            PT->>S: PollTaskResult::NeedsRouting(tx, status)
            S->>S: route_poll_results → handle_confirmation_result
        else Still Pending
            PT->>IFQ: push(tx) [poll_attempts++]
        end
    end

    note over S,PT: Graceful Shutdown
    S->>S: drain processor channel
    S->>S: drain_in_flight (poll_in_flight loop, 30s timeout)
    S->>PT: poll_shutdown.cancel()
    S->>PT: await poll_task_handle

Loading

_{Reviews (1): Last reviewed commit: "feat(operator): fire-and-forget mint sen..." | Re-trigger Greptile}