SK Queue · Features

Five chapters of a queue engine
built for transaction safety.

From deterministic fits to database-level exclusion locks, explore the features that keep Softknack's waiting lines fair.

01

Intake and OTP verification — secure self-service

Guests join via QR code, and callers check in automatically. Every entry goes through verification before allocating line placement, eliminating spam checks.

fig 01 · verified intake path guest scans QR requests SMS OTP verifies code fair intake checker idempotent · rate-limited valid session token issued ✓ placed in active queue table ✓ expected wait computed ✓
scan QROTP gateverified ✓

Instant guest validation

Contactless check-ins verify mobile numbers with 4-digit SMS OTP tokens, ensuring lines stay real.

header keycheck table1 entry

Strict idempotency

Incoming client requests carry idempotency keys. Network retries will not double-book line positions.

voice callhold queuequeued ✓

Omni-channel hooks

Intake adapters process check-ins from chat endpoints, voice call holds, and physical walk-in cards alike.

02

Allocation — Postgres-level concurrency locks

Double-bookings and skipped lines happen when multiple threads try to write simultaneously. SK Queue gates allocations inside serialized Postgres database transactions.

fig 02 · concurrency allocation locks client_01 (select) client_02 (select) SELECT FOR UPDATE NOWAIT locks row index · skip locked entries state = locked transaction committed ✓ allocated table_id: 14
lock rowseat fittedseated

Row-level locks

Forces sequential checks on active entries via SELECT FOR UPDATE, blocking parallel double-seats.

fits tablezone matchallocated ✓

Fitted constraints matching

Queries Calendar resource structures to fit party bounds and zones automatically before allocating.

SKIP LOCKEDnext threadfree flow

Non-blocking queue skips

Applies SKIP LOCKED to pass over rows currently undergoing validation, keeping line throughput smooth.

03

Estimation — learning wait-time intervals

Dynamic calculations provide realistic expectations. The engine monitors historical session exits and applies learning confidence math to estimate wait times.

fig 03 · wait interval estimator mean exit interval Wilson Estimator Math w = (p + z²/2n) / (1 + z²/n) expected wait window 14 - 18 minutes (CI: 95%)
exit eventsaverage outbaseline

Historical tracking

Tracks actual checkout durations to establish an active baseline per resource type and location.

std devconfidenceWilson CI ✓

Wilson lower-bound math

Calculates conservative wait times using statistical confidence bands, adjusting to sudden peak hour changes.

active queuere-evalauto-adjust

Auto-adjusting position

Updates remaining wait estimates automatically as ahead parties checkout or drop out of line.

04

Ledger and Tenancy — append-only compliance

Safety and compliance are locked in the database layer. Database triggers protect transaction history, and multi-tenant RLS rules shield organization datasets.

fig 04 · security isolation ledger Tenant_A (org_01) ├─ checkin_id: q_019A ├─ phone: +91 9840... └─ database policy: OK Row-Level Security (RLS) Tenant_B (org_02) ├─ checkin_id: q_019B ├─ phone: +91 9962... └─ database policy: OK
INSERT ONLYblock deletetamper-proof

Append-only event log

Database triggers raise errors on UPDATE or DELETE requests. Historical line moves cannot be modified.

org_id scopeDB policyisolated ✓

Row Level Security (RLS)

Fences datasets using PostgreSQL policies checking tenant keys, preventing cross-organization leaks.

retention limitPII scrubbingswept ✓

DPDP compliance sweeps

Sanitizes guest PII fields automatically from closed entries while keeping statistical log records intact.

05

Notifications — failsafe omni-channel alerts

Updates reach customers wherever they are. Connected directly to the backbone event engine, SK Queue coordinates SMS, WhatsApp, and email alerts.

fig 05 · notification fallback flow queue.seat_ready dispatch event trigger 1. whatsapp api undelivered ✗ 2. check channel fallback timeout: 60 seconds delivered via SMS ✓ telecom carrier route
whatsappsms fallbackdelivered

Channel fallbacks

Sends SMS alerts if WhatsApp deliveries fail, ensuring customers never miss their seat notification.

confirm pathno responseno-show fee

Auto-cancellation windows

Tracks response timers automatically, releasing tables or slots if guests do not respond within set bounds.

webhook logcorrelationtraced ✓

Traceable notifications

Binds custom trace IDs to every dispatch event, logging delivery timestamps directly to the contact timeline.

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