1  #ifndef Py_INTERNAL_GIL_H
       2  #define Py_INTERNAL_GIL_H
       3  #ifdef __cplusplus
       4  extern "C" {
       5  #endif
       6  
       7  #ifndef Py_BUILD_CORE
       8  #  error "this header requires Py_BUILD_CORE define"
       9  #endif
      10  
      11  #include "pycore_atomic.h"    /* _Py_atomic_address */
      12  #include "pycore_condvar.h"   /* PyCOND_T */
      13  
      14  #ifndef Py_HAVE_CONDVAR
      15  #  error You need either a POSIX-compatible or a Windows system!
      16  #endif
      17  
      18  /* Enable if you want to force the switching of threads at least
      19     every `interval`. */
      20  #undef FORCE_SWITCHING
      21  #define FORCE_SWITCHING
      22  
      23  struct _gil_runtime_state {
      24      /* microseconds (the Python API uses seconds, though) */
      25      unsigned long interval;
      26      /* Last PyThreadState holding / having held the GIL. This helps us
      27         know whether anyone else was scheduled after we dropped the GIL. */
      28      _Py_atomic_address last_holder;
      29      /* Whether the GIL is already taken (-1 if uninitialized). This is
      30         atomic because it can be read without any lock taken in ceval.c. */
      31      _Py_atomic_int locked;
      32      /* Number of GIL switches since the beginning. */
      33      unsigned long switch_number;
      34      /* This condition variable allows one or several threads to wait
      35         until the GIL is released. In addition, the mutex also protects
      36         the above variables. */
      37      PyCOND_T cond;
      38      PyMUTEX_T mutex;
      39  #ifdef FORCE_SWITCHING
      40      /* This condition variable helps the GIL-releasing thread wait for
      41         a GIL-awaiting thread to be scheduled and take the GIL. */
      42      PyCOND_T switch_cond;
      43      PyMUTEX_T switch_mutex;
      44  #endif
      45  };
      46  
      47  #ifdef __cplusplus
      48  }
      49  #endif
      50  #endif /* !Py_INTERNAL_GIL_H */