feat: expose background service lifecycle (#36895)

packages/core/src/util/process-lock.ts

@@ -0,0 +1,181 @@
+import { dlopen, read, type Pointer } from "bun:ffi"
+import { closeSync, existsSync, mkdirSync, openSync } from "node:fs"
+import { connect, createServer, type Server, type Socket } from "node:net"
+import path from "node:path"
+import { Effect, Schema } from "effect"
+import { Hash } from "./hash"
+
+export namespace ProcessLock {
+  export class HeldError extends Schema.TaggedErrorClass<HeldError>()("ProcessLockHeldError", {
+    file: Schema.String,
+  }) {
+    override get message() {
+      return `Process lock is already held: ${this.file}`
+    }
+  }
+
+  export class SystemError extends Schema.TaggedErrorClass<SystemError>()("ProcessLockSystemError", {
+    file: Schema.String,
+    operation: Schema.Literals(["open", "acquire"]),
+    code: Schema.String,
+  }) {
+    override get message() {
+      return `Process lock ${this.operation} failed for ${this.file}: ${this.code}`
+    }
+  }
+
+  export type LockError = HeldError | SystemError
+
+  const acquirePosix = Effect.fnUntraced(function* (file: string) {
+    const fd = yield* Effect.try({
+      try: () => {
+        mkdirSync(path.dirname(file), { recursive: true })
+        return openSync(file, "a+", 0o600)
+      },
+      catch: (cause) =>
+        new SystemError({
+          file,
+          operation: "open",
+          code: cause instanceof Error ? cause.message : String(cause),
+        }),
+    })
+    const result = yield* Effect.try({
+      try: () => lock(fd),
+      catch: (cause) =>
+        new SystemError({
+          file,
+          operation: "acquire",
+          code: cause instanceof Error ? cause.message : String(cause),
+        }),
+    }).pipe(
+      Effect.tapError(() =>
+        Effect.sync(() => {
+          closeSync(fd)
+        }),
+      ),
+    )
+    if (result.acquired) {
+      return fd
+    }
+    closeSync(fd)
+    return yield* result.held
+      ? new HeldError({ file })
+      : new SystemError({ file, operation: "acquire", code: String(result.code) })
+  })
+
+  export const acquire = Effect.fn("ProcessLock.acquire")(function* (file: string) {
+    if (process.platform === "win32") {
+      yield* Effect.acquireRelease(acquireWindows(file), closeWindows)
+      return
+    }
+    yield* Effect.acquireRelease(acquirePosix(file), (fd) =>
+      Effect.sync(() => {
+        closeSync(fd)
+      }),
+    )
+  })
+}
+
+type Result =
+  | { readonly acquired: true }
+  | { readonly acquired: false; readonly held: true }
+  | { readonly acquired: false; readonly held: false; readonly code: number }
+
+const LOCK_EX = 2
+const LOCK_NB = 4
+const DARWIN_EWOULDBLOCK = 35
+const LINUX_EWOULDBLOCK = 11
+
+function lock(fd: number): Result {
+  if (process.platform === "darwin") return lockDarwin(fd)
+  if (process.platform === "linux") return lockLinux(fd)
+  throw new Error(`Unsupported process lock platform: ${process.platform}`)
+}
+
+function lockDarwin(fd: number): Result {
+  const library = dlopen("/usr/lib/libSystem.B.dylib", {
+    flock: { args: ["i32", "i32"], returns: "i32" },
+    __error: { args: [], returns: "ptr" },
+  })
+  try {
+    const result = library.symbols.flock(fd, LOCK_EX | LOCK_NB)
+    const code = result === 0 ? 0 : errorCode(library.symbols.__error())
+    if (result === 0) return { acquired: true }
+    if (code === DARWIN_EWOULDBLOCK) return { acquired: false, held: true }
+    return { acquired: false, held: false, code }
+  } finally {
+    library.close()
+  }
+}
+
+function lockLinux(fd: number): Result {
+  const musl = `/lib/libc.musl-${process.arch === "arm64" ? "aarch64" : "x86_64"}.so.1`
+  const library = dlopen(existsSync(musl) ? musl : "libc.so.6", {
+    flock: { args: ["i32", "i32"], returns: "i32" },
+    __errno_location: { args: [], returns: "ptr" },
+  })
+  try {
+    const result = library.symbols.flock(fd, LOCK_EX | LOCK_NB)
+    const code = result === 0 ? 0 : errorCode(library.symbols.__errno_location())
+    if (result === 0) return { acquired: true }
+    if (code === LINUX_EWOULDBLOCK) return { acquired: false, held: true }
+    return { acquired: false, held: false, code }
+  } finally {
+    library.close()
+  }
+}
+
+function errorCode(pointer: Pointer | null) {
+  if (pointer === null) throw new Error("Failed to read process lock error code")
+  return read.i32(pointer, 0)
+}
+
+function acquireWindows(file: string) {
+  return Effect.callback<Server, ProcessLock.LockError>((resume) => {
+    const server = createServer()
+    let probe: Socket | undefined
+    const pipe = `\\\\.\\pipe\\opencode-process-lock-${Hash.sha256(path.resolve(file).toLowerCase())}`
+    const onError = (cause: NodeJS.ErrnoException) => {
+      server.off("listening", onListening)
+      probe = connect(pipe)
+      const onProbeError = () => {
+        probe?.off("connect", onConnect)
+        resume(
+          Effect.fail(
+            new ProcessLock.SystemError({
+              file,
+              operation: "acquire",
+              code: cause.code ?? cause.message,
+            }),
+          ),
+        )
+      }
+      const onConnect = () => {
+        probe?.off("error", onProbeError)
+        probe?.destroy()
+        resume(Effect.fail(new ProcessLock.HeldError({ file })))
+      }
+      probe.once("connect", onConnect)
+      probe.once("error", onProbeError)
+    }
+    const onListening = () => {
+      server.off("error", onError)
+      resume(Effect.succeed(server))
+    }
+    server.once("error", onError)
+    server.once("listening", onListening)
+    server.on("connection", (socket) => socket.destroy())
+    server.listen(pipe)
+    return Effect.sync(() => {
+      probe?.destroy()
+      server.close()
+    })
+  })
+}
+
+function closeWindows(server: Server) {
+  return Effect.callback<void>((resume) => {
+    if (!server.listening) return resume(Effect.void)
+    server.close((error) => resume(error ? Effect.die(error) : Effect.void))
+  })
+}