feat(core): add fence to make all methods strongly consistent when syncing (#22679)

packages/opencode/src/server/fence.ts

@@ -0,0 +1,81 @@
+import type { MiddlewareHandler } from "hono"
+import { Database, inArray } from "@/storage/db"
+import { EventSequenceTable } from "@/sync/event.sql"
+import { Workspace } from "@/control-plane/workspace"
+import type { WorkspaceID } from "@/control-plane/schema"
+import { Log } from "@/util/log"
+
+const HEADER = "x-opencode-sync"
+type State = Record<string, number>
+const log = Log.create({ service: "fence" })
+
+export function load(ids?: string[]) {
+  const rows = Database.use((db) => {
+    if (!ids?.length) {
+      return db.select().from(EventSequenceTable).all()
+    }
+
+    return db.select().from(EventSequenceTable).where(inArray(EventSequenceTable.aggregate_id, ids)).all()
+  })
+
+  return Object.fromEntries(rows.map((row) => [row.aggregate_id, row.seq])) as State
+}
+
+export function diff(prev: State, next: State) {
+  const ids = new Set([...Object.keys(prev), ...Object.keys(next)])
+  return Object.fromEntries(
+    [...ids]
+      .map((id) => [id, next[id] ?? -1] as const)
+      .filter(([id, seq]) => {
+        return (prev[id] ?? -1) !== seq
+      }),
+  ) as State
+}
+
+export function parse(headers: Headers) {
+  const raw = headers.get(HEADER)
+  if (!raw) return
+
+  let data
+
+  try {
+    data = JSON.parse(raw)
+  } catch (err) {
+    return
+  }
+
+  if (!data || typeof data !== "object") return
+
+  return Object.fromEntries(
+    Object.entries(data).filter(([id, seq]) => {
+      return typeof id === "string" && Number.isInteger(seq)
+    }),
+  ) as State
+}
+
+export async function wait(workspaceID: WorkspaceID, state: State, signal?: AbortSignal) {
+  log.info("waiting for state", {
+    workspaceID,
+    state,
+  })
+  await Workspace.waitForSync(workspaceID, state, signal)
+  log.info("state fully synced", {
+    workspaceID,
+    state,
+  })
+}
+
+export const FenceMiddleware: MiddlewareHandler = async (c, next) => {
+  if (c.req.method === "GET" || c.req.method === "HEAD" || c.req.method === "OPTIONS") return next()
+
+  const prev = load()
+  await next()
+  const current = diff(prev, load())
+
+  if (Object.keys(current).length > 0) {
+    log.info("header", {
+      diff: current,
+    })
+    c.res.headers.set(HEADER, JSON.stringify(current))
+  }
+}