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cpython/Modules/hashlib.h
Gregory P. Smith 2e5d8a90aa
gh-99108: Release the GIL around hashlib built-in computation (#104675)
This matches the GIL releasing behavior of our existing `_hashopenssl`
module, extending it to the HACL* built-ins.

Includes adding comments to better describe the ENTER/LEAVE macros
purpose and explain the lock strategy in both existing and new code.
2023-05-23 00:06:41 +00:00

67 lines
2.5 KiB
C

/* Common code for use by all hashlib related modules. */
/*
* Given a PyObject* obj, fill in the Py_buffer* viewp with the result
* of PyObject_GetBuffer. Sets an exception and issues the erraction
* on any errors, e.g. 'return NULL' or 'goto error'.
*/
#define GET_BUFFER_VIEW_OR_ERROR(obj, viewp, erraction) do { \
if (PyUnicode_Check((obj))) { \
PyErr_SetString(PyExc_TypeError, \
"Strings must be encoded before hashing");\
erraction; \
} \
if (!PyObject_CheckBuffer((obj))) { \
PyErr_SetString(PyExc_TypeError, \
"object supporting the buffer API required"); \
erraction; \
} \
if (PyObject_GetBuffer((obj), (viewp), PyBUF_SIMPLE) == -1) { \
erraction; \
} \
if ((viewp)->ndim > 1) { \
PyErr_SetString(PyExc_BufferError, \
"Buffer must be single dimension"); \
PyBuffer_Release((viewp)); \
erraction; \
} \
} while(0)
#define GET_BUFFER_VIEW_OR_ERROUT(obj, viewp) \
GET_BUFFER_VIEW_OR_ERROR(obj, viewp, return NULL)
/*
* Helper code to synchronize access to the hash object when the GIL is
* released around a CPU consuming hashlib operation. All code paths that
* access a mutable part of obj must be enclosed in an ENTER_HASHLIB /
* LEAVE_HASHLIB block or explicitly acquire and release the lock inside
* a PY_BEGIN / END_ALLOW_THREADS block if they wish to release the GIL for
* an operation.
*
* These only drop the GIL if the lock acquisition itself is likely to
* block. Thus the non-blocking acquire gating the GIL release for a
* blocking lock acquisition. The intent of these macros is to surround
* the assumed always "fast" operations that you aren't releasing the
* GIL around. Otherwise use code similar to what you see in hash
* function update() methods.
*/
#include "pythread.h"
#define ENTER_HASHLIB(obj) \
if ((obj)->lock) { \
if (!PyThread_acquire_lock((obj)->lock, 0)) { \
Py_BEGIN_ALLOW_THREADS \
PyThread_acquire_lock((obj)->lock, 1); \
Py_END_ALLOW_THREADS \
} \
}
#define LEAVE_HASHLIB(obj) \
if ((obj)->lock) { \
PyThread_release_lock((obj)->lock); \
}
/* TODO(gpshead): We should make this a module or class attribute
* to allow the user to optimize based on the platform they're using. */
#define HASHLIB_GIL_MINSIZE 2048