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0c89056fe5
PyMutex is a one byte lock with fast, inlineable lock and unlock functions for the common uncontended case. The design is based on WebKit's WTF::Lock. PyMutex is built using the _PyParkingLot APIs, which provides a cross-platform futex-like API (based on WebKit's WTF::ParkingLot). This internal API will be used for building other synchronization primitives used to implement PEP 703, such as one-time initialization and events. This also includes tests and a mini benchmark in Tools/lockbench/lockbench.py to compare with the existing PyThread_type_lock. Uncontended acquisition + release: * Linux (x86-64): PyMutex: 11 ns, PyThread_type_lock: 44 ns * macOS (arm64): PyMutex: 13 ns, PyThread_type_lock: 18 ns * Windows (x86-64): PyMutex: 13 ns, PyThread_type_lock: 38 ns PR Overview: The primary purpose of this PR is to implement PyMutex, but there are a number of support pieces (described below). * PyMutex: A 1-byte lock that doesn't require memory allocation to initialize and is generally faster than the existing PyThread_type_lock. The API is internal only for now. * _PyParking_Lot: A futex-like API based on the API of the same name in WebKit. Used to implement PyMutex. * _PyRawMutex: A word sized lock used to implement _PyParking_Lot. * PyEvent: A one time event. This was used a bunch in the "nogil" fork and is useful for testing the PyMutex implementation, so I've included it as part of the PR. * pycore_llist.h: Defines common operations on doubly-linked list. Not strictly necessary (could do the list operations manually), but they come up frequently in the "nogil" fork. ( Similar to https://man.freebsd.org/cgi/man.cgi?queue) --------- Co-authored-by: Eric Snow <ericsnowcurrently@gmail.com>
63 lines
1.6 KiB
C
63 lines
1.6 KiB
C
// The _PySemaphore API a simplified cross-platform semaphore used to implement
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// wakeup/sleep.
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#ifndef Py_INTERNAL_SEMAPHORE_H
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#define Py_INTERNAL_SEMAPHORE_H
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#ifndef Py_BUILD_CORE
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# error "this header requires Py_BUILD_CORE define"
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#endif
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#include "pycore_time.h" // _PyTime_t
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#ifdef MS_WINDOWS
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# define WIN32_LEAN_AND_MEAN
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# include <windows.h>
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#elif defined(HAVE_PTHREAD_H)
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# include <pthread.h>
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#elif defined(HAVE_PTHREAD_STUBS)
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# include "cpython/pthread_stubs.h"
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#else
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# error "Require native threads. See https://bugs.python.org/issue31370"
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#endif
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#if defined(_POSIX_SEMAPHORES) && (_POSIX_SEMAPHORES+0) != -1
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# define _Py_USE_SEMAPHORES
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# include <semaphore.h>
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#endif
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#ifdef __cplusplus
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extern "C" {
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#endif
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typedef struct _PySemaphore {
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#if defined(MS_WINDOWS)
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HANDLE platform_sem;
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#elif defined(_Py_USE_SEMAPHORES)
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sem_t platform_sem;
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#else
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pthread_mutex_t mutex;
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pthread_cond_t cond;
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int counter;
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#endif
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} _PySemaphore;
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// Puts the current thread to sleep until _PySemaphore_Wakeup() is called.
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// If `detach` is true, then the thread will detach/release the GIL while
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// sleeping.
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PyAPI_FUNC(int)
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_PySemaphore_Wait(_PySemaphore *sema, _PyTime_t timeout_ns, int detach);
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// Wakes up a single thread waiting on sema. Note that _PySemaphore_Wakeup()
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// can be called before _PySemaphore_Wait().
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PyAPI_FUNC(void)
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_PySemaphore_Wakeup(_PySemaphore *sema);
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// Initializes/destroys a semaphore
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PyAPI_FUNC(void) _PySemaphore_Init(_PySemaphore *sema);
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PyAPI_FUNC(void) _PySemaphore_Destroy(_PySemaphore *sema);
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#ifdef __cplusplus
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}
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#endif
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#endif /* !Py_INTERNAL_SEMAPHORE_H */
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