fix(code-runtime): flatten worker JSON transport

2026-07-22 19:09:27 +08:00
parent d6f478488d
commit ef2de530ff
13 changed files with 352 additions and 58 deletions
@@ -150,4 +150,185 @@ export function snapshotCodeJsonValue(value: unknown): CodeJsonValue | undefined
  }
  return root
 }
+
+interface ArrayWireToken {
+  kind: 'array'
+  length: number
+}
+
+interface ObjectWireToken {
+  kind: 'object'
+  keys: string[]
+}
+
+type WorkerJsonToken = null | boolean | number | string | ArrayWireToken | ObjectWireToken
+
+/**
+ * A pre-order, bounded-depth transport for one lossless JSON value. Container
+ * markers and scalar leaves share one flat token array, so `worker_threads`
+ * never has to structured-clone the value's application nesting.
+ */
+export type WorkerJsonWire = WorkerJsonToken[]
+
+/**
+ * Flatten one validated JSON value for the worker-thread message port.
+ * @param value - the lossless JSON value to transport.
+ * @returns a pre-order token stream whose own nesting is bounded.
+ */
+export function encodeWorkerJson(value: CodeJsonValue): WorkerJsonWire {
+  const wire: WorkerJsonWire = []
+  const pending: CodeJsonValue[] = [value]
+  for (let current = pending.pop(); current !== undefined; current = pending.pop()) {
+    if (current === null || typeof current === 'boolean' || typeof current === 'number' || typeof current === 'string') {
+      wire.push(current)
+      continue
+    }
+    if (Array.isArray(current)) {
+      wire.push({ kind: 'array', length: current.length })
+      for (let index = current.length - 1; index >= 0; index--) {
+        const item = current[index]
+        if (item === undefined) throw new Error('cannot encode a sparse JSON array')
+        pending.push(item)
+      }
+      continue
+    }
+    const keys = Object.keys(current)
+    wire.push({ kind: 'object', keys })
+    for (let index = keys.length - 1; index >= 0; index--) {
+      const key = keys[index]
+      /* v8 ignore next -- the loop is bounded by the captured key count. */
+      if (key === undefined) throw new Error('cannot encode a missing JSON object key')
+      const item = current[key]
+      if (item === undefined) throw new Error('cannot encode an undefined JSON object property')
+      pending.push(item)
+    }
+  }
+  return wire
+}
+
+type DecodeFrame =
+  | { kind: 'array'; target: CodeJsonValue[]; length: number; index: number }
+  | { kind: 'object'; target: Record<string, CodeJsonValue>; keys: string[]; index: number }
+
+/** Whether an array contains exactly its dense indexed slots and `length`. */
+function isDenseArray(value: unknown[]): boolean {
+  if (!hasPlainArrayPrototype(value) || Reflect.ownKeys(value).length !== value.length + 1) return false
+  for (let index = 0; index < value.length; index++) {
+    if (!Object.hasOwn(value, index)) return false
+  }
+  return true
+}
+
+/** Return one exact container marker, or reject any extra/missing fields. */
+function containerToken(value: object): ArrayWireToken | ObjectWireToken | undefined {
+  if (Array.isArray(value) || !hasPlainObjectPrototype(value)) return undefined
+  const keys = enumerableStringKeys(value)
+  if (keys === undefined) return undefined
+  const token = value as Record<string, unknown>
+  if (token.kind === 'array') {
+    if (keys.length !== 2 || !keys.includes('kind') || !keys.includes('length')) return undefined
+    const length = token.length
+    return typeof length === 'number' && Number.isSafeInteger(length) && length >= 0
+      ? { kind: 'array', length }
+      : undefined
+  }
+  if (token.kind === 'object') {
+    if (keys.length !== 2 || !keys.includes('kind') || !keys.includes('keys')) return undefined
+    const objectKeys = token.keys
+    if (!Array.isArray(objectKeys) || !isDenseArray(objectKeys)) return undefined
+    const unique = new Set<string>()
+    const normalizedKeys: string[] = []
+    for (const key of objectKeys as unknown[]) {
+      if (typeof key !== 'string' || unique.has(key)) return undefined
+      unique.add(key)
+      normalizedKeys.push(key)
+    }
+    return { kind: 'object', keys: normalizedKeys }
+  }
+  return undefined
+}
+
+/**
+ * Rebuild one lossless JSON value from the flat worker-thread wire format.
+ * Malformed or incomplete traffic returns `undefined`; traversal is iterative
+ * and therefore independent of the transported value's application depth.
+ * @param input - untrusted message-port payload.
+ * @returns the detached JSON value, or `undefined` when the wire is invalid.
+ */
+export function decodeWorkerJson(input: unknown): CodeJsonValue | undefined {
+  try {
+    if (!Array.isArray(input) || !isDenseArray(input) || input.length === 0) return undefined
+    const wire = input as unknown[]
+    const frames: DecodeFrame[] = []
+    let root: CodeJsonValue | undefined
+    let rootAssigned = false
+
+    const attach = (value: CodeJsonValue): boolean => {
+      const parent = frames.at(-1)
+      if (!parent) {
+        if (rootAssigned) return false
+        root = value
+        rootAssigned = true
+        return true
+      }
+      /* v8 ignore next -- completed frames are popped before another token can attach. */
+      if (parent.index >= (parent.kind === 'array' ? parent.length : parent.keys.length)) return false
+      if (parent.kind === 'array') {
+        parent.target.push(value)
+      } else {
+        const key = parent.keys[parent.index]
+        /* v8 ignore next -- object frames are built from validated keys and their exact length. */
+        if (key === undefined) return false
+        Object.defineProperty(parent.target, key, {
+          value,
+          enumerable: true,
+          configurable: true,
+          writable: true,
+        })
+      }
+      parent.index += 1
+      return true
+    }
+
+    for (let tokenIndex = 0; tokenIndex < wire.length; tokenIndex++) {
+      const token = wire[tokenIndex]
+      let value: CodeJsonValue
+      let frame: DecodeFrame | undefined
+      if (token === null || typeof token === 'boolean' || typeof token === 'string') {
+        value = token
+      } else if (typeof token === 'number') {
+        if (!Number.isFinite(token) || Object.is(token, -0)) return undefined
+        value = token
+      } else {
+        if (typeof token !== 'object') return undefined
+        const marker = containerToken(token)
+        if (!marker) return undefined
+        const remainingTokens = wire.length - tokenIndex - 1
+        if (marker.kind === 'array') {
+          if (marker.length > remainingTokens) return undefined
+          const target: CodeJsonValue[] = []
+          value = target
+          if (marker.length > 0) frame = { kind: 'array', target, length: marker.length, index: 0 }
+        } else {
+          if (marker.keys.length > remainingTokens) return undefined
+          const target: Record<string, CodeJsonValue> = {}
+          value = target
+          if (marker.keys.length > 0) frame = { kind: 'object', target, keys: marker.keys, index: 0 }
+        }
+      }
+      if (!attach(value)) return undefined
+      if (frame) frames.push(frame)
+      while (frames.length > 0) {
+        const current = frames.at(-1)
+        /* v8 ignore next -- the loop condition guarantees a final frame. */
+        if (current === undefined) break
+        if (current.index < (current.kind === 'array' ? current.length : current.keys.length)) break
+        frames.pop()
+      }
+    }
+    return frames.length === 0 ? root : undefined
+  } catch {
+    return undefined
+  }
+}
 /* jscpd:ignore-end */