refactor(file-time): effectify FileTimeService with Semaphore locks (#17835)

packages/opencode/src/file/time.ts

@@ -1,71 +1,115 @@
-import { Instance } from "../project/instance"
 import { Log } from "../util/log"
-import { Flag } from "../flag/flag"
+import { Flag } from "@/flag/flag"
 import { Filesystem } from "../util/filesystem"
+import { Effect, Layer, ServiceMap, Semaphore } from "effect"
+import { runPromiseInstance } from "@/effect/runtime"
+import type { SessionID } from "@/session/schema"
+
+const log = Log.create({ service: "file.time" })
+
+export namespace FileTimeService {
+  export interface Service {
+    readonly read: (sessionID: SessionID, file: string) => Effect.Effect<void>
+    readonly get: (sessionID: SessionID, file: string) => Effect.Effect<Date | undefined>
+    readonly assert: (sessionID: SessionID, filepath: string) => Effect.Effect<void>
+    readonly withLock: <T>(filepath: string, fn: () => Promise<T>) => Effect.Effect<T>
+  }
+}
+
+type Stamp = {
+  readonly read: Date
+  readonly mtime: number | undefined
+  readonly ctime: number | undefined
+  readonly size: number | undefined
+}
+
+function stamp(file: string): Stamp {
+  const stat = Filesystem.stat(file)
+  const size = typeof stat?.size === "bigint" ? Number(stat.size) : stat?.size
+  return {
+    read: new Date(),
+    mtime: stat?.mtime?.getTime(),
+    ctime: stat?.ctime?.getTime(),
+    size,
+  }
+}
+
+function session(reads: Map<SessionID, Map<string, Stamp>>, sessionID: SessionID) {
+  let value = reads.get(sessionID)
+  if (!value) {
+    value = new Map<string, Stamp>()
+    reads.set(sessionID, value)
+  }
+  return value
+}
+
+export class FileTimeService extends ServiceMap.Service<FileTimeService, FileTimeService.Service>()(
+  "@opencode/FileTime",
+) {
+  static readonly layer = Layer.effect(
+    FileTimeService,
+    Effect.gen(function* () {
+      const disableCheck = yield* Flag.OPENCODE_DISABLE_FILETIME_CHECK
+      const reads = new Map<SessionID, Map<string, Stamp>>()
+      const locks = new Map<string, Semaphore.Semaphore>()
+
+      function getLock(filepath: string) {
+        let lock = locks.get(filepath)
+        if (!lock) {
+          lock = Semaphore.makeUnsafe(1)
+          locks.set(filepath, lock)
+        }
+        return lock
+      }
+
+      return FileTimeService.of({
+        read: Effect.fn("FileTimeService.read")(function* (sessionID: SessionID, file: string) {
+          log.info("read", { sessionID, file })
+          session(reads, sessionID).set(file, stamp(file))
+        }),
+
+        get: Effect.fn("FileTimeService.get")(function* (sessionID: SessionID, file: string) {
+          return reads.get(sessionID)?.get(file)?.read
+        }),
+
+        assert: Effect.fn("FileTimeService.assert")(function* (sessionID: SessionID, filepath: string) {
+          if (disableCheck) return
+
+          const time = reads.get(sessionID)?.get(filepath)
+          if (!time) throw new Error(`You must read file ${filepath} before overwriting it. Use the Read tool first`)
+          const next = stamp(filepath)
+          const changed = next.mtime !== time.mtime || next.ctime !== time.ctime || next.size !== time.size
+
+          if (changed) {
+            throw new Error(
+              `File ${filepath} has been modified since it was last read.\nLast modification: ${new Date(next.mtime ?? next.read.getTime()).toISOString()}\nLast read: ${time.read.toISOString()}\n\nPlease read the file again before modifying it.`,
+            )
+          }
+        }),
+
+        withLock: Effect.fn("FileTimeService.withLock")(function* <T>(filepath: string, fn: () => Promise<T>) {
+          const lock = getLock(filepath)
+          return yield* Effect.promise(fn).pipe(lock.withPermits(1))
+        }),
+      })
+    }),
+  )
+}
 
 export namespace FileTime {
-  const log = Log.create({ service: "file.time" })
-  // Per-session read times plus per-file write locks.
-  // All tools that overwrite existing files should run their
-  // assert/read/write/update sequence inside withLock(filepath, ...)
-  // so concurrent writes to the same file are serialized.
-  export const state = Instance.state(() => {
-    const read: {
-      [sessionID: string]: {
-        [path: string]: Date | undefined
-      }
-    } = {}
-    const locks = new Map<string, Promise<void>>()
-    return {
-      read,
-      locks,
-    }
-  })
-
-  export function read(sessionID: string, file: string) {
-    log.info("read", { sessionID, file })
-    const { read } = state()
-    read[sessionID] = read[sessionID] || {}
-    read[sessionID][file] = new Date()
+  export function read(sessionID: SessionID, file: string) {
+    return runPromiseInstance(FileTimeService.use((s) => s.read(sessionID, file)))
   }
 
-  export function get(sessionID: string, file: string) {
-    return state().read[sessionID]?.[file]
+  export function get(sessionID: SessionID, file: string) {
+    return runPromiseInstance(FileTimeService.use((s) => s.get(sessionID, file)))
+  }
+
+  export async function assert(sessionID: SessionID, filepath: string) {
+    return runPromiseInstance(FileTimeService.use((s) => s.assert(sessionID, filepath)))
   }
 
   export async function withLock<T>(filepath: string, fn: () => Promise<T>): Promise<T> {
-    const current = state()
-    const currentLock = current.locks.get(filepath) ?? Promise.resolve()
-    let release: () => void = () => {}
-    const nextLock = new Promise<void>((resolve) => {
-      release = resolve
-    })
-    const chained = currentLock.then(() => nextLock)
-    current.locks.set(filepath, chained)
-    await currentLock
-    try {
-      return await fn()
-    } finally {
-      release()
-      if (current.locks.get(filepath) === chained) {
-        current.locks.delete(filepath)
-      }
-    }
-  }
-
-  export async function assert(sessionID: string, filepath: string) {
-    if (Flag.OPENCODE_DISABLE_FILETIME_CHECK === true) {
-      return
-    }
-
-    const time = get(sessionID, filepath)
-    if (!time) throw new Error(`You must read file ${filepath} before overwriting it. Use the Read tool first`)
-    const mtime = Filesystem.stat(filepath)?.mtime
-    // Allow a 50ms tolerance for Windows NTFS timestamp fuzziness / async flushing
-    if (mtime && mtime.getTime() > time.getTime() + 50) {
-      throw new Error(
-        `File ${filepath} has been modified since it was last read.\nLast modification: ${mtime.toISOString()}\nLast read: ${time.toISOString()}\n\nPlease read the file again before modifying it.`,
-      )
-    }
+    return runPromiseInstance(FileTimeService.use((s) => s.withLock(filepath, fn)))
   }
 }

packages/opencode/src/file/watcher.ts

@@ -72,7 +72,8 @@ export class FileWatcherService extends ServiceMap.Service<FileWatcherService, F
     FileWatcherService,
     Effect.gen(function* () {
       const instance = yield* InstanceContext
-      if (yield* Flag.OPENCODE_EXPERIMENTAL_DISABLE_FILEWATCHER) return FileWatcherService.of({ init })
+      if (yield* Flag.OPENCODE_EXPERIMENTAL_DISABLE_FILEWATCHER)
+        return FileWatcherService.of({ init })
 
       log.info("init", { directory: instance.directory })