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/* 
  Logic for a better replacement of PyGILState_Ensure(). 
 
  This version is ready to handle the case of a non-Python-started 
  thread in which we do a large number of calls to CFFI callbacks.  If 
  we were to rely on PyGILState_Ensure() for that, we would constantly 
  be creating and destroying PyThreadStates---it is slow, and 
  PyThreadState_Delete() will actually walk the list of all thread 
  states, making it O(n). :-( 
 
  This version only creates one PyThreadState object the first time we 
  see a given thread, and keep it alive until the thread is really 
  shut down, using a destructor on the tls key. 
*/ 
 
#include <pthread.h> 
#include "misc_thread_common.h" 
 
 
static pthread_key_t cffi_tls_key; 
 
static void init_cffi_tls(void) 
{ 
    if (pthread_key_create(&cffi_tls_key, &cffi_thread_shutdown) != 0) 
        PyErr_SetString(PyExc_OSError, "pthread_key_create() failed"); 
} 
 
static struct cffi_tls_s *_make_cffi_tls(void) 
{ 
    void *p = calloc(1, sizeof(struct cffi_tls_s)); 
    if (p == NULL) 
        return NULL; 
    if (pthread_setspecific(cffi_tls_key, p) != 0) { 
        free(p); 
        return NULL; 
    } 
    return p; 
} 
 
static struct cffi_tls_s *get_cffi_tls(void) 
{ 
    void *p = pthread_getspecific(cffi_tls_key); 
    if (p == NULL) 
        p = _make_cffi_tls(); 
    return (struct cffi_tls_s *)p; 
} 
 
#define save_errno      save_errno_only 
#define restore_errno   restore_errno_only