Nashorn（es6）损坏的函数作用域

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英文:

Nashorn (es6) corrupted function scope

问题

我目前正在调查Nashorn js脚本引擎中的以下问题，并且我会感谢您的意见。以下是代码段（使用Kotlin编写）：

  1. fun main() {
  2.     val brokenScript = """
  3.         function fn() {
  4.             const object1 = { "name": "Pepa" };
  5.             print(object1.name);
  6.             const descriptor1 = Object.getOwnPropertyDescriptor(object1, 'name');
  7.             print(descriptor1.configurable);
  8.             print(eval("3+1"));
  9.         }
  10.         fn();
  11.     """.trimIndent()
  12.     
  13.     NashornScriptEngineFactory()
  14.         .getScriptEngine("--no-deprecation-warning", "--language=es6", "--log=compiler:finest,fields,recompile:fine")
  15.         .let { (it as Compilable).compile(brokenScript) }
  16.         .also { script -> script.eval() }
  17. }

错误信息：

  1. Exception in thread "main" javax.script.ScriptException: ReferenceError: "descriptor1" is not defined in <eval> at line number 8
  2. 	at jdk.scripting.nashorn/jdk.nashorn.api.scripting.NashornScriptEngine.throwAsScriptException(NashornScriptEngine.java:477)
  3. 	at jdk.scripting.nashorn/jdk.nashorn.api.scripting.NashornScriptEngine.evalImpl(NashornScriptEngine.java:461)
  4. 	at jdk.scripting.nashorn/jdk.nashorn.api.scripting.NashornScriptEngine$3.eval(NashornScriptEngine.java:517)
  5. 	at java.scripting/javax.script.CompiledScript.eval(CompiledScript.java:103)
  6. 	at MainKt.main(Main.kt:19)
  7. 	at MainKt.main(Main.kt)
  8. Caused by: <eval>:8 ReferenceError: "descriptor1" is not defined
  9. 	at jdk.scripting.nashorn/jdk.nashorn.internal.runtime.ECMAErrors.error(ECMAErrors.java:57)
  10. 	at jdk.scripting.nashorn/jdk.nashorn.internal.runtime.ECMAErrors.referenceError(ECMAErrors.java:319)
  11. 	at jdk.scripting.nashorn/jdk.nashorn.internal.runtime.ECMAErrors.referenceError(ECMAErrors.java:291)
  12. 	at jdk.scripting.nashorn/jdk.nashorn.internal.runtime.ECMAErrors.referenceError(ECMAErrors.java:278)
  13. 	at jdk.scripting.nashorn/jdk.nashorn.internal.runtime.AccessorProperty.checkUndeclared(AccessorProperty.java:571)
  14. ...

观察结果：

  • 问题受到eval函数的影响 - 从脚本中省略它有帮助 - 还需要嵌套在函数中 - 在顶层工作正常
  • 问题受到Object.getOwnPropertyDescriptor函数的影响 - 从脚本中省略它有帮助
  • 问题受到作用域的影响 - 将变量声明从具有作用域的（const/let）更改为无作用域的var有帮助
  • 输出日志包含caught RewriteException [pp=3, type=object, value='Pepa')]

当前假设：

Object.getOwnPropertyDescriptor函数引发UnwarrantedOptimismException，强制函数重新编译。
重新编译脚本的作用域受损。通常，作用域是通过eval函数的使用来操作的，因此在运行时重新编译期间可能会不正确地解析这个问题。
访问作用域变量失败。

我希望的结果是什么？（按优先顺序排列）

  • 它可以像在节点中执行时一样工作 - 显然
  • 在不关闭es6功能的情况下在编译时识别问题
  • 禁用eval函数可以防止问题 - 我尝试过从Bindings对象中删除eval，但是脚本在编译阶段就已损坏，并且稍后将修改的Bindings传递给script.eval(bindings) - 因此脚本在到达eval行之前仍会失败
  • （实际上，这是我试图避免的）通过关闭es6功能来绕过问题（删除**--language=es6** - 这会导致脚本在编译时由于使用作用域变量（const/let）而失败）

（我知道Nashorn已经被弃用，将被移除。）

英文:

I am currently investigating following issue in Nashorn js scripting engine and I'd appreciate your input.
Following code snippet fails execution (code in Kotlin):

  1. fun main() {
  2.  &#160; &#160;val brokenScript = &quot;&quot;&quot;
  3.  &#160; &#160; &#160; &#160;function fn() {
  4.  &#160; &#160; &#160; &#160; &#160; &#160;const object1 = { &quot;name&quot;: &quot;Pepa&quot; };
  5.  &#160; &#160; &#160; &#160; &#160; &#160;print(object1.name);
  6.  &#160; &#160; &#160; &#160; &#160; &#160;const descriptor1 = Object.getOwnPropertyDescriptor(object1, &#39;name&#39;);
  7.  &#160; &#160; &#160; &#160; &#160; &#160;print(descriptor1.configurable);
  8.  &#160; &#160; &#160; &#160; &#160; &#160;print(eval(&quot;3+1&quot;));
  9.  &#160; &#160; &#160; &#160;}
  10.  &#160; &#160; &#160; &#160;fn();
  11.  &#160; &#160;&quot;&quot;&quot;.trimIndent()
  12.  &#160; &#160;NashornScriptEngineFactory()
  13.  &#160; &#160; &#160; &#160; &#160; &#160;.getScriptEngine(&quot;--no-deprecation-warning&quot;, &quot;--language=es6&quot;, &quot;--log=compiler:finest,fields,recompile:fine&quot;)
  14.  &#160; &#160; &#160; &#160; &#160; &#160;.let { (it as Compilable).compile(brokenScript) }
  15.  &#160; &#160; &#160; &#160; &#160; &#160;.also { script -&gt; script.eval() }
  16. }

Error:

  1. Exception in thread &quot;main&quot; javax.script.ScriptException: ReferenceError: &quot;descriptor1&quot; is not defined in &lt;eval&gt; at line number 8
  2. 	at jdk.scripting.nashorn/jdk.nashorn.api.scripting.NashornScriptEngine.throwAsScriptException(NashornScriptEngine.java:477)
  3. 	at jdk.scripting.nashorn/jdk.nashorn.api.scripting.NashornScriptEngine.evalImpl(NashornScriptEngine.java:461)
  4. 	at jdk.scripting.nashorn/jdk.nashorn.api.scripting.NashornScriptEngine$3.eval(NashornScriptEngine.java:517)
  5. 	at java.scripting/javax.script.CompiledScript.eval(CompiledScript.java:103)
  6. 	at MainKt.main(Main.kt:19)
  7. 	at MainKt.main(Main.kt)
  8. Caused by: &lt;eval&gt;:8 ReferenceError: &quot;descriptor1&quot; is not defined
  9. 	at jdk.scripting.nashorn/jdk.nashorn.internal.runtime.ECMAErrors.error(ECMAErrors.java:57)
  10. 	at jdk.scripting.nashorn/jdk.nashorn.internal.runtime.ECMAErrors.referenceError(ECMAErrors.java:319)
  11. 	at jdk.scripting.nashorn/jdk.nashorn.internal.runtime.ECMAErrors.referenceError(ECMAErrors.java:291)
  12. 	at jdk.scripting.nashorn/jdk.nashorn.internal.runtime.ECMAErrors.referenceError(ECMAErrors.java:278)
  13. 	at jdk.scripting.nashorn/jdk.nashorn.internal.runtime.AccessorProperty.checkUndeclared(AccessorProperty.java:571)
  14. ...

Observations:

  • issue is influenced by eval function - ommiting it from script helps - also need to be nested in function - works fine at top level
  • issue is influenced by Object.getOwnPropertyDescriptor function - ommiting it from script helps
  • issue is influenced by scoping - changing variable declaration from scoped (const/let) to unscoped var helps
  • output log contains caught RewriteException [pp=3, type=object, value=&#39;Pepa&#39;)]

Current hypothesis:

Object.getOwnPropertyDescriptor function raises UnwarrantedOptimismException that forces the function to recompile.
Scope of recompiled script is corrupted. Usually the scope is manipulated by eval function usage so it can declare variables - maybe this is resolved incorrectly during the runtime recompilation.
Accessing scoped variables fails.

What outcome I hope for?(in order of preference)

  • it works just as when executed in node - obviously
  • issue is identified at compile time without turning off es6 features
  • disabling eval function prevents the issue - I tried this by removing eval from Bindings object but script is corrupted at compilation phase and modified Bindings are passed later to script.eval(bindings) - so the script still fails before reaching eval line
  • (this is actually what I try to avoid) bypassing issue by turning off es6 features (removing --language=es6 - this forces the script to fail at compile time due to usage of scoped variables (const/let)

(I am aware that nashorn is deprecated and will be removed.)

答案1

得分: 0

我们在Nashorn和JDK 9+中也遇到了类似的问题。似乎是“乐观类型”导致了这个问题。尝试禁用Nashorn的乐观类型。

  1. .getScriptEngine("--no-deprecation-warning", "--language=es6", "--log=compiler:finest,fields,recompile:fine", "--optimistic-types=false")

参考：https://openjdk.java.net/jeps/196

英文:

We also had similar problem with Nashorn and JDK 9+. It seems like optimistic types causes this problem. Try disabling optimistic types for Nashorn

  1. .getScriptEngine(&quot;--no-deprecation-warning&quot;, &quot;--language=es6&quot;, &quot;--log=compiler:finest,fields,recompile:fine&quot;, &quot;--optimistic-types=false&quot;)

Ref: https://openjdk.java.net/jeps/196

huangapple
  • 本文由 发表于 2020年5月5日 20:32:08
  • 转载请务必保留本文链接：https://java.coder-hub.com/61613216.html
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