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>

app/services/nntp_shares.ts

@@ -0,0 +1,90 @@
+import db from '@adonisjs/lucid/services/db'
+import coordinatorConfig from '#config/coordinator'
+
+/** A share whose process hasn't synced for this long is gone: its connections closed with it. */
+const STALE_SECONDS = 60
+/** Syncs one at a time (pg_advisory_xact_lock). */
+const LOCK = 2_026_101_875
+
+export interface Share {
+  name: string
+  priority: number
+  /** Kept whatever the others want (as far as the total goes, by priority). */
+  min: number
+  /** What it could use now. */
+  want: number
+  /** Connections it has open (or may have: a lane without one yet counts). */
+  open: number
+}
+
+/** What each share should have: its minimum first, then by priority what it wants, up to the total. */
+export function targets(total: number, shares: Share[]): Map<string, number> {
+  const ordered = [...shares].sort((a, b) => b.priority - a.priority || a.name.localeCompare(b.name))
+  const target = new Map<string, number>()
+  let left = total
+  for (const s of ordered) {
+    const t = Math.min(s.min, left)
+    target.set(s.name, t)
+    left -= t
+  }
+  for (const s of ordered) {
+    const more = Math.min(Math.max(s.want - target.get(s.name)!, 0), left)
+    target.set(s.name, target.get(s.name)! + more)
+    left -= more
+  }
+  return target
+}
+
+/**
+ * The connections `self` may have: its target, but no more than the others leave over. Another share holds what it
+ * has open or was granted, whichever is more (it may open up to its grant until its next sync tells it otherwise),
+ * so the account never goes over the total: a share grows only into what the others closed or gave up.
+ */
+export function grant(total: number, self: Share, others: (Share & { granted: number })[]): number {
+  const target = targets(total, [self, ...others]).get(self.name)!
+  const held = others.reduce((sum, o) => sum + Math.max(o.open, o.granted), 0)
+  return Math.max(0, Math.min(target, total - held))
+}
+
+/**
+ * A process's share of the NNTP account's connections (LOG.md 2026-10-18 (75)): the coordinator and the prober had a
+ * fixed split, and with history paused the coordinator's 38 stood idle while the prober's 8 were its limit. Each
+ * syncs every nntpShares.everyMs (what it wants and has open) and gets what it may open; one wanting less closes
+ * connections as they come free, and the other grows as those show up closed.
+ */
+export class NntpShare {
+  granted = 0
+
+  constructor(
+    readonly name: string,
+    private priority: number,
+    readonly min: number,
+    readonly max: number
+  ) {}
+
+  async sync(want: number, open: number): Promise<number> {
+    const self: Share = { name: this.name, priority: this.priority, min: this.min, want: Math.min(Math.max(want, this.min), this.max), open }
+    const total = coordinatorConfig.nntpShares.total
+    this.granted = await db.transaction(async (trx) => {
+      await trx.rawQuery(`SELECT pg_advisory_xact_lock(?)`, [LOCK])
+      const { rows } = await trx.rawQuery(
+        `SELECT name, priority, min, want, open, granted FROM nntp_shares WHERE name <> ? AND heartbeat_at > now() - make_interval(secs => ?)`,
+        [this.name, STALE_SECONDS]
+      )
+      const granted = grant(total, self, rows)
+      await trx.rawQuery(
+        `INSERT INTO nntp_shares (name, priority, min, want, open, granted, heartbeat_at) VALUES (?, ?, ?, ?, ?, ?, now())
+         ON CONFLICT (name) DO UPDATE SET priority = excluded.priority, min = excluded.min, want = excluded.want,
+           open = excluded.open, granted = excluded.granted, heartbeat_at = now()`,
+        [this.name, this.priority, this.min, self.want, open, granted]
+      )
+      return granted
+    })
+    return this.granted
+  }
+
+  /** Stopping: its connections are closed, the others needn't wait for the row to go stale. */
+  async leave() {
+    await db.from('nntp_shares').where('name', this.name).delete()
+  }
+}