##// END OF EJS Templates
repo: avoid copying/updating a dict on every `repo.__getitem__`...
repo: avoid copying/updating a dict on every `repo.__getitem__` This has some mild performance benefits. I'm looking into a pathological case where one of our `hg log` invocations takes several seconds, and according to hyperfine this reduces the wall time of the entire operation (running in chg) from: ``` Time (mean ± σ): 7.390 s ± 0.106 s [User: 7.058 s, System: 0.271 s] Range (min … max): 7.300 s … 7.625 s ``` to: ``` Time (mean ± σ): 7.046 s ± 0.091 s [User: 6.714 s, System: 0.279 s] Range (min … max): 6.916 s … 7.169 s ``` Note: the log command is slow due to an issue in our custom stuff executing `repo[<arg>]` 298,800 times. This performance improvement is likely not noticeable during normal operation, but I don't feel like it's making the code more difficult to understand, and every small bit helps. Differential Revision: https://phab.mercurial-scm.org/D9022

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util.h
74 lines | 2.0 KiB | text/x-c | CLexer
/*
util.h - utility functions for interfacing with the various python APIs.
This software may be used and distributed according to the terms of
the GNU General Public License, incorporated herein by reference.
*/
#ifndef _HG_UTIL_H_
#define _HG_UTIL_H_
#include "compat.h"
#if PY_MAJOR_VERSION >= 3
#define IS_PY3K
#endif
/* helper to switch things like string literal depending on Python version */
#ifdef IS_PY3K
#define PY23(py2, py3) py3
#else
#define PY23(py2, py3) py2
#endif
/* clang-format off */
typedef struct {
PyObject_HEAD
char state;
int mode;
int size;
int mtime;
} dirstateTupleObject;
/* clang-format on */
extern PyTypeObject dirstateTupleType;
#define dirstate_tuple_check(op) (Py_TYPE(op) == &dirstateTupleType)
#ifndef MIN
#define MIN(a, b) (((a) < (b)) ? (a) : (b))
#endif
/* VC9 doesn't include bool and lacks stdbool.h based on my searching */
#if defined(_MSC_VER) || __STDC_VERSION__ < 199901L
#define true 1
#define false 0
typedef unsigned char bool;
#else
#include <stdbool.h>
#endif
static inline PyObject *_dict_new_presized(Py_ssize_t expected_size)
{
/* _PyDict_NewPresized expects a minused parameter, but it actually
creates a dictionary that's the nearest power of two bigger than the
parameter. For example, with the initial minused = 1000, the
dictionary created has size 1024. Of course in a lot of cases that
can be greater than the maximum load factor Python's dict object
expects (= 2/3), so as soon as we cross the threshold we'll resize
anyway. So create a dictionary that's at least 3/2 the size. */
return _PyDict_NewPresized(((1 + expected_size) / 2) * 3);
}
/* Convert a PyInt or PyLong to a long. Returns false if there is an
error, in which case an exception will already have been set. */
static inline bool pylong_to_long(PyObject *pylong, long *out)
{
*out = PyLong_AsLong(pylong);
/* Fast path to avoid hitting PyErr_Occurred if the value was obviously
* not an error. */
if (*out != -1) {
return true;
}
return PyErr_Occurred() == NULL;
}
#endif /* _HG_UTIL_H_ */