define: DUK_USE_EXEC_TIMEOUT_CHECK
feature_snippet: |
  #undef DUK_USE_EXEC_TIMEOUT_CHECK
  #if defined(DUK_OPT_EXEC_TIMEOUT_CHECK)
  #define DUK_USE_EXEC_TIMEOUT_CHECK(udata)  DUK_OPT_EXEC_TIMEOUT_CHECK((udata))
  #endif
introduced: 1.2.0
requires:
  - DUK_USE_INTERRUPT_COUNTER
default: false
tags:
  - execution
  - sandbox
  - experimental
description: >
  NOTE: This mechanism is EXPERIMENTAL and the details may change
  between releases.

  Provide a hook to check for bytecode execution timeout.  The macro gets
  a void ptr userdata argument (the userdata given to duk_heap_create())
  and must evaluate to a duk_bool_t.  Duktape calls the macro as:
  "if (DUK_USE_EXEC_TIMEOUT_CHECK(udata)) { ... }".

  The macro is called occasionally by the Duktape bytecode executor (i.e.
  when executing Ecmascript code), typically from a few times per second
  to a hundred times per second, but the interval varies a great deal
  depending on what kind of code is being executed.

  To indicate an execution timeout, the macro must return a non-zero value.
  When that happens, Duktape starts to bubble a ``RangeError`` outwards
  until control has been returned to the original protected call made by
  the application.  Until that happens, the exec timeout macro must always
  return non-zero to indicate an execution timeout is still in progress.

  This mechanism and its limitations is described in more detail in
  doc/sandboxing.rst.