fix!: napi_adjust_external_memory no longer grow wasm memory (#207)

Author: toyobayashi

packages/emnapi/src/core/memory.ts

@@ -1,5 +1,4 @@
 import { emnapiCtx, emnapiEnv } from 'emnapi:shared'
-import { wasmMemory } from 'emscripten:runtime'
 import { from64, makeSetValue } from 'emscripten:parse-tools'
 import { $CHECK_ENV, $CHECK_ARG } from '../macro'
 import { $emnapiSetValueI64 as emnapiSetValueI64 } from '../util'
@@ -14,24 +13,13 @@ export function napi_adjust_external_memory (
   const envObject = emnapiEnv
   $CHECK_ARG!(envObject, adjusted_value)
 
-  const change_in_bytes_number = Number(change_in_bytes)
-
-  if (change_in_bytes_number < 0) {
-    return envObject.setLastError(napi_status.napi_invalid_arg)
-  }
-
-  const old_size = wasmMemory.buffer.byteLength
-  let new_size = old_size + change_in_bytes_number
-  new_size = new_size + ((65536 - new_size % 65536) % 65536)
-  if (wasmMemory.grow((new_size - old_size + 65535) >> 16) === -1) {
-    return envObject.setLastError(napi_status.napi_generic_failure)
-  }
+  let adjusted_memory = emnapiCtx.adjustAmountOfExternalAllocatedMemory(change_in_bytes)
 
   from64('adjusted_value')
   if (emnapiCtx.features.BigInt) {
-    makeSetValue('adjusted_value', 0, 'wasmMemory.buffer.byteLength', 'i64')
+    makeSetValue('adjusted_value', 0, 'adjusted_memory', 'i64')
   } else {
-    emnapiSetValueI64(adjusted_value, wasmMemory.buffer.byteLength)
+    emnapiSetValueI64(adjusted_value, Number(adjusted_memory))
   }
 
   return envObject.clearLastError()

packages/emnapi/src/emscripten/memory.ts

@@ -1,14 +1,11 @@
-import { wasmMemory } from 'emscripten:runtime'
 import { emnapiCtx, emnapiEnv } from 'emnapi:shared'
 import { from64, makeSetValue } from 'emscripten:parse-tools'
 import { $emnapiSetValueI64 as emnapiSetValueI64 } from '../util'
 import { $CHECK_ENV } from '../macro'
 
 /* eslint-disable @stylistic/indent */
-declare function _emscripten_resize_heap (requested: number): boolean
 
 /**
- * @__deps emscripten_resize_heap
  * @__sig ipjp
  */
 export function napi_adjust_external_memory (
@@ -20,38 +17,28 @@ export function napi_adjust_external_memory (
   $CHECK_ENV!(env)
   const envObject = emnapiEnv
 
-  let change_in_bytes: number
+  let change_in_bytes: bigint
 
 // #if WASM_BIGINT
   if (!high) return envObject.setLastError(napi_status.napi_invalid_arg)
-  change_in_bytes = Number(low)
+  change_in_bytes = BigInt(low)
 // #else
   if (!adjusted_value) return envObject.setLastError(napi_status.napi_invalid_arg)
-  change_in_bytes = (low >>> 0) + (high * Math.pow(2, 32))
+  change_in_bytes = BigInt(low >>> 0) + (BigInt(high) << BigInt(32))
 // #endif
 
-  if (change_in_bytes < 0) {
-    return envObject.setLastError(napi_status.napi_invalid_arg)
-  }
-
-  if (change_in_bytes > 0) {
-    const old_size = wasmMemory.buffer.byteLength
-    const new_size = old_size + change_in_bytes
-    if (!_emscripten_resize_heap(new_size)) {
-      return envObject.setLastError(napi_status.napi_generic_failure)
-    }
-  }
+  const adjusted_memory = emnapiCtx.adjustAmountOfExternalAllocatedMemory(change_in_bytes)
 
 // #if WASM_BIGINT
   from64('high')
   if (emnapiCtx.features.BigInt) {
-    makeSetValue('high', 0, 'wasmMemory.buffer.byteLength', 'i64')
+    makeSetValue('high', 0, 'adjusted_memory', 'i64')
   } else {
-    emnapiSetValueI64(high, wasmMemory.buffer.byteLength)
+    emnapiSetValueI64(high, Number(adjusted_memory))
   }
 // #else
   from64('adjusted_value')
-  makeSetValue('adjusted_value', 0, 'wasmMemory.buffer.byteLength', 'i64')
+  makeSetValue('adjusted_value', 0, 'adjusted_memory', 'i64')
 // #endif
 
   return envObject.clearLastError()

packages/runtime/src/Context.ts

@@ -249,6 +249,10 @@ export class Context {
     return this.isolate.createResolver<T>()
   }
 
+  public adjustAmountOfExternalAllocatedMemory (changeInBytes: number | bigint): bigint {
+    return this.isolate.adjustAmountOfExternalAllocatedMemory(changeInBytes)
+  }
+
   public createEnv (
     filename: string,
     moduleApiVersion: number,

packages/runtime/src/ExternalMemory.ts

@@ -0,0 +1,27 @@
+const kMaxReasonableBytes = BigInt(1) << BigInt(60)
+const kMinReasonableBytes = -kMaxReasonableBytes
+
+export class ExternalMemory {
+  total: bigint
+  onChange: ((current: bigint, old: bigint, delta: bigint) => any) | null
+
+  constructor (onChange?: (current: bigint, old: bigint, delta: bigint) => any) {
+    this.total = BigInt(0)
+    this.onChange = onChange ?? null
+  }
+
+  adjust (changeInBytes: number | bigint): bigint {
+    changeInBytes = BigInt(changeInBytes)
+    if (!(kMinReasonableBytes <= changeInBytes && changeInBytes < kMaxReasonableBytes)) {
+      throw new RangeError(`changeInBytes ${changeInBytes} is out of reasonable range`)
+    }
+    const old = this.total
+    this.total += changeInBytes
+    const amount = this.total
+    const onChange = this.onChange
+    if (changeInBytes) {
+      onChange?.(amount, old, changeInBytes)
+    }
+    return amount
+  }
+}

packages/runtime/src/Isolate.ts

@@ -8,16 +8,19 @@ import { detectFeatures, type Resolver, type Features } from './util'
 import type { HandleScope, ICallbackInfo } from './HandleScope'
 import { External, getExternalValue, isExternal } from './External'
 import { deletePrivate, getPrivate, hasPrivate, Private, setPrivate } from './Private'
+import { ExternalMemory } from './ExternalMemory'
 
 export interface IsolateOptions {
   features?: Partial<Features>
+  onExternalMemoryChange?: (current: bigint, old: bigint, delta: bigint) => any
 }
 
 export class Isolate {
   private _lastException
   private _globalThis: typeof globalThis
   private _scopeStore: ScopeStore
   private _handleStore: HandleStore
+  private _externalMemory: ExternalMemory
   /** @internal */
   public globalHandleStore: PersistentStore
   public readonly features: Features
@@ -29,6 +32,7 @@ export class Isolate {
     this._handleStore = new HandleStore(this.features)
     this.globalHandleStore = new PersistentStore()
     this._lastException = new Persistent<any>(this)
+    this._externalMemory = new ExternalMemory(options?.onExternalMemoryChange)
   }
 
   //#region Local handles
@@ -125,6 +129,12 @@ export class Isolate {
   }
   //#endregion
 
+  //#region External Memory
+  public adjustAmountOfExternalAllocatedMemory (changeInBytes: number | bigint): bigint {
+    return this._externalMemory.adjust(changeInBytes)
+  }
+  //#endregion
+
   //#region Templates
   public createSignature (template: FunctionTemplate): Signature {
     return new Signature(template)