- Even if you don't use file.xreadlines(), you may expect a speedup on
line-by-line input. The file.readline() method has been optimized
- quite a bit in platform-specific ways, both on Windows (using an
- incredibly complex, but nevertheless thread-safe), and on systems
- (like Linux) that support flockfile(), getc_unlocked(), and
- funlockfile(). In addition, the fileinput module, while still slow,
- has been sped up too, by using file.readlines(sizehint).
+ quite a bit in platform-specific ways: on systems (like Linux) that
+ support flockfile(), getc_unlocked(), and funlockfile(), those are
+ used by default. On systems (like Windows) without getc_unlocked(),
+ a complicated (but still thread-safe) method using fgets() is used by
+ default.
+
+ You can force use of the fgets() method by #define'ing
+ USE_FGETS_IN_GETLINE at build time (it may be faster than
+ getc_unlocked()).
+
+ You can force fgets() not to be used by #define'ing
+ DONT_USE_FGETS_IN_GETLINE (this is the first thing to try if std test
+ test_bufio.py fails -- and let us know if it does!).
+
+- In addition, the fileinput module, while still slower than the other
+ methods on most platforms, has been sped up too, by using
+ file.readlines(sizehint).
- Support for run-time warnings has been added, including a new
command line option (-W) to specify the disposition of warnings.
}
/**************************************************************************
-Win32 MS routine to get next line.
+Routine to get next line using platform fgets().
Under MSVC 6:
MS realloc is also slow.
-In the usual case, we have one pleasantly small line already sitting in a
-stdio buffer, and we optimize heavily for that case.
-
-CAUTION: This routine cheats, relying on that MSVC 6 fgets doesn't overwrite
-any buffer positions to the right of the terminating null byte. Seems
-unlikely that will change in the future, but ... std test test_bufio should
-catch it if that changes.
+Reports from other platforms on this method vs getc_unlocked (which MS doesn't
+have):
+ Linux a wash
+ Solaris a wash
+ Tru64 Unix getline_via_fgets significantly faster
+
+CAUTION: The C std isn't clear about this: in those cases where fgets
+writes something into the buffer, can it write into any position beyond the
+required trailing null byte? MSVC 6 fgets does not, and no platform is (yet)
+known on which it does; and it would be a strange way to code fgets. Still,
+getline_via_fgets may not work correctly if it does. The std test
+test_bufio.py should fail if platform fgets() routinely writes beyond the
+trailing null byte. #define DONT_USE_FGETS_IN_GETLINE to disable this code.
**************************************************************************/
-/* if Win32 and MS's compiler */
-#if defined(MS_WIN32) && defined(_MSC_VER)
-#define USE_MS_GETLINE_HACK
+/* Use this routine if told to, or by default on non-get_unlocked()
+ * platforms unless told not to. Yikes! Let's spell that out:
+ * On a platform with getc_unlocked():
+ * By default, use getc_unlocked().
+ * If you want to use fgets() instead, #define USE_FGETS_IN_GETLINE.
+ * On a platform without getc_unlocked():
+ * By default, use fgets().
+ * If you don't want to use fgets(), #define DONT_USE_FGETS_IN_GETLINE.
+ */
+#if !defined(USE_FGETS_IN_GETLINE) && !defined(HAVE_GETC_UNLOCKED)
+#define USE_FGETS_IN_GETLINE
+#endif
+
+#if defined(DONT_USE_FGETS_IN_GETLINE) && defined(USE_FGETS_IN_GETLINE)
+#undef USE_FGETS_IN_GETLINE
#endif
-#ifdef USE_MS_GETLINE_HACK
+#ifdef USE_FGETS_IN_GETLINE
static PyObject*
-ms_getline_hack(FILE *fp)
+getline_via_fgets(FILE *fp)
{
/* INITBUFSIZE is the maximum line length that lets us get away with the fast
* no-realloc path. get_line uses 100 for its initial size, but isn't trying
char* pvfree; /* address of next free slot */
char* pvend; /* address one beyond last free slot */
char* p; /* temp */
- char msbuf[INITBUFSIZE];
+ char buf[INITBUFSIZE];
/* Optimize for normal case: avoid _PyString_Resize if at all
- * possible via first reading into auto msbuf.
+ * possible via first reading into auto buf.
*/
Py_BEGIN_ALLOW_THREADS
- memset(msbuf, '\n', INITBUFSIZE);
- p = fgets(msbuf, INITBUFSIZE, fp);
+ memset(buf, '\n', INITBUFSIZE);
+ p = fgets(buf, INITBUFSIZE, fp);
Py_END_ALLOW_THREADS
if (p == NULL) {
return v;
}
/* fgets read *something* */
- p = memchr(msbuf, '\n', INITBUFSIZE);
+ p = memchr(buf, '\n', INITBUFSIZE);
if (p != NULL) {
/* Did the \n come from fgets or from us?
* Since fgets stops at the first \n, and then writes \0, if
* could not have come from us, since the \n's we filled the
* buffer with have only more \n's to the right.
*/
- pvend = msbuf + INITBUFSIZE;
+ pvend = buf + INITBUFSIZE;
if (p+1 < pvend && *(p+1) == '\0') {
/* It's from fgets: we win! In particular, we
* haven't done any mallocs yet, and can build the
* final result on the first try.
*/
- v = PyString_FromStringAndSize(msbuf, p - msbuf + 1);
+ v = PyString_FromStringAndSize(buf, p - buf + 1);
return v;
}
/* Must be from us: fgets didn't fill the buffer and didn't
* find a newline, so it must be the last and newline-free
* line of the file.
*/
- assert(p > msbuf && *(p-1) == '\0');
- v = PyString_FromStringAndSize(msbuf, p - msbuf - 1);
+ assert(p > buf && *(p-1) == '\0');
+ v = PyString_FromStringAndSize(buf, p - buf - 1);
return v;
}
/* yuck: fgets overwrote all the newlines, i.e. the entire buffer.
* So this line isn't over yet, or maybe it is but we're exactly at
* EOF; in either case, we're tired <wink>.
*/
- assert(msbuf[INITBUFSIZE-1] == '\0');
+ assert(buf[INITBUFSIZE-1] == '\0');
total_v_size = INITBUFSIZE + INCBUFSIZE;
v = PyString_FromStringAndSize((char*)NULL, (int)total_v_size);
if (v == NULL)
return v;
/* copy over everything except the last null byte */
- memcpy(BUF(v), msbuf, INITBUFSIZE-1);
+ memcpy(BUF(v), buf, INITBUFSIZE-1);
pvfree = BUF(v) + INITBUFSIZE - 1;
/* Keep reading stuff into v; if it ever ends successfully, break
#undef INITBUFSIZE
#undef INCBUFSIZE
}
-#endif /* ifdef USE_MS_GETLINE_HACK */
+#endif /* ifdef USE_FGETS_IN_GETLINE */
/* Internal routine to get a line.
Size argument interpretation:
size_t n1, n2;
PyObject *v;
-#ifdef USE_MS_GETLINE_HACK
-
+#ifdef USE_FGETS_IN_GETLINE
if (n <= 0)
- return ms_getline_hack(fp);
+ return getline_via_fgets(fp);
#endif
n2 = n > 0 ? n : 100;
v = PyString_FromStringAndSize((char *)NULL, n2);
file_xreadlines(PyFileObject *f, PyObject *args)
{
static PyObject* xreadlines_function = NULL;
-
+
if (!PyArg_ParseTuple(args, ":xreadlines"))
return NULL;
-
+
if (!xreadlines_function) {
PyObject *xreadlines_module =
PyImport_ImportModule("xreadlines");
projects / thirdparty / Python / cpython.git / commitdiff
