NNTP shares: the account's connections shared by priority

The coordinator (38) and the prober (8) had a fixed split; with history
paused the coordinator's stood idle while the prober's were its limit.
nntp_shares: each process syncs every 15 s (priority, minimum, what it could
use, what it has open) and gets what it may open: minimums first, then by
priority what each wants, growing only into connections the others closed
or gave up. The pool's size and the prober's lanes follow the grant; the
coordinator doubles its want while work waits for a connection, else asks
for its peak in use and a margin; the prober wants its maximum unless the
queue is dry. Claims scale with the lanes.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

tests/functional/nntp_shares.spec.ts

@@ -0,0 +1,53 @@
+import { test } from '@japa/runner'
+import db from '@adonisjs/lucid/services/db'
+import testUtils from '@adonisjs/core/services/test_utils'
+import coordinatorConfig from '#config/coordinator'
+import { grant, targets, NntpShare } from '#services/nntp_shares'
+
+test.group('NNTP shares', (group) => {
+  group.each.setup(() => testUtils.db().withGlobalTransaction())
+
+  test('targets: minimums first, then by priority what each wants', ({ assert }) => {
+    const coordinator = { name: 'coordinator', priority: 2, min: 8, want: 38, open: 0 }
+    const prober = { name: 'prober', priority: 1, min: 2, want: 40, open: 0 }
+    // History running: the coordinator all it wants, the prober the rest.
+    assert.deepEqual(Object.fromEntries(targets(45, [prober, coordinator])), { coordinator: 38, prober: 7 })
+    // History paused: the coordinator its minimum (or what it uses), the prober the rest.
+    assert.deepEqual(Object.fromEntries(targets(45, [prober, { ...coordinator, want: 8 }])), { coordinator: 8, prober: 37 })
+    // Wanting more than its minimum doesn't take another's minimum.
+    assert.deepEqual(Object.fromEntries(targets(45, [prober, { ...coordinator, want: 60 }])), { coordinator: 43, prober: 2 })
+  })
+
+  test('grant: growing only into connections the others closed or gave up', ({ assert }) => {
+    const prober = { name: 'prober', priority: 1, min: 2, want: 40, open: 37, granted: 37 }
+    const coordinator = { name: 'coordinator', priority: 2, min: 8, want: 38, open: 8 }
+    // History came back: the prober still holds 37, the coordinator keeps its 8 for now.
+    assert.equal(grant(45, coordinator, [prober]), 8)
+    // The prober syncs: its target is 7, its grant goes down at once.
+    assert.equal(grant(45, { ...prober, open: 37 }, [{ ...coordinator, granted: 8 }]), 7)
+    // Its connections not closed yet: still held.
+    assert.equal(grant(45, coordinator, [{ ...prober, granted: 7, open: 30 }]), 15)
+    // Closed: the coordinator gets all it wants.
+    assert.equal(grant(45, coordinator, [{ ...prober, granted: 7, open: 7 }]), 38)
+  })
+
+  test('sync: each process its row; a process gone (no heartbeat) holds nothing', async ({ assert }) => {
+    const total = coordinatorConfig.nntpShares.total
+    const coordinator = new NntpShare('coordinator', 2, 8, 38)
+    const prober = new NntpShare('prober', 1, 2, total)
+    assert.equal(await coordinator.sync(8, 0), 8)
+    assert.equal(await prober.sync(total, 0), total - 8)
+    // The coordinator wants all: the prober holds its grant until it has synced and closed them.
+    assert.equal(await coordinator.sync(38, 8), 8)
+    assert.equal(await prober.sync(total, total - 8), total - 38)
+    assert.equal(await coordinator.sync(38, 8), 8)
+    assert.equal(await prober.sync(total, total - 38), total - 38)
+    assert.equal(await coordinator.sync(38, 8), 38)
+
+    // The prober's process died: after a minute without a sync its share is free.
+    await db.from('nntp_shares').where('name', 'prober').update({ open: total, granted: total, heartbeat_at: new Date(Date.now() - 120_000) })
+    assert.equal(await coordinator.sync(38, 38), 38)
+    await coordinator.leave()
+    assert.equal(await prober.sync(total, 0), total)
+  })
+})