MS Win32 .readline() speedup, as discussed on Python-Dev. This is a tricky
variant that never needs to "search from the right".
Also fixed unlikely memory leak in get_line, if string size overflows INTMAX.
Also new std test test_bufio to make sure .readline() works.
diff --git a/Lib/test/output/test_bufio b/Lib/test/output/test_bufio
new file mode 100644
index 0000000..c153797
--- /dev/null
+++ b/Lib/test/output/test_bufio
@@ -0,0 +1 @@
+test_bufio
diff --git a/Lib/test/test_bufio.py b/Lib/test/test_bufio.py
new file mode 100644
index 0000000..1a820d4
--- /dev/null
+++ b/Lib/test/test_bufio.py
@@ -0,0 +1,60 @@
+from test_support import TestFailed, TESTFN
+
+# Simple test to ensure that optimizations in fileobject.c deliver
+# the expected results. For best testing, run this under a debug-build
+# Python too (to exercise asserts in the C code).
+
+# Repeat string 'pattern' as often as needed to reach total length
+# 'length'. Then call try_one with that string, a string one larger
+# than that, and a string one smaller than that. The main driver
+# feeds this all small sizes and various powers of 2, so we exercise
+# all likely stdio buffer sizes, and "off by one" errors on both
+# sides.
+def drive_one(pattern, length):
+ q, r = divmod(length, len(pattern))
+ teststring = pattern * q + pattern[:r]
+ assert len(teststring) == length
+ try_one(teststring)
+ try_one(teststring + "x")
+ try_one(teststring[:-1])
+
+# Write s + "\n" + s to file, then open it and ensure that successive
+# .readline()s deliver what we wrote.
+def try_one(s):
+ # Since C doesn't guarantee we can write/read arbitrary bytes in text
+ # files, use binary mode.
+ f = open(TESTFN, "wb")
+ # write once with \n and once without
+ f.write(s)
+ f.write("\n")
+ f.write(s)
+ f.close()
+ f = open(TESTFN, "rb")
+ line = f.readline()
+ if line != s + "\n":
+ raise TestFailed("Expected %r got %r" % (s + "\n", line))
+ line = f.readline()
+ if line != s:
+ raise TestFailed("Expected %r got %r" % (s, line))
+ line = f.readline()
+ if line:
+ raise TestFailed("Expected EOF but got %r" % line)
+ f.close()
+
+# A pattern with prime length, to avoid simple relationships with
+# stdio buffer sizes.
+primepat = "1234567890\00\01\02\03\04\05\06\07"
+
+nullpat = "\0" * 1000
+
+try:
+ for size in range(1, 257) + [512, 1000, 1024, 2048, 4096, 8192, 10000,
+ 16384, 32768, 65536, 1000000]:
+ drive_one(primepat, size)
+ drive_one(nullpat, size)
+finally:
+ try:
+ import os
+ os.unlink(TESTFN)
+ except:
+ pass
diff --git a/Objects/fileobject.c b/Objects/fileobject.c
index aaa6a90..5dd2460 100644
--- a/Objects/fileobject.c
+++ b/Objects/fileobject.c
@@ -244,7 +244,7 @@
/* a portable fseek() function
return 0 on success, non-zero on failure (with errno set) */
int
-#if defined(HAVE_LARGEFILE_SUPPORT) && SIZEOF_OFF_T < 8 && SIZEOF_FPOS_T >= 8
+#if defined(HAVE_LARGEFILE_SUPPORT) && SIZEOF_OFF_T < 8 && SIZEOF_FPOS_T >= 8
_portable_fseek(FILE *fp, fpos_t offset, int whence)
#else
_portable_fseek(FILE *fp, off_t offset, int whence)
@@ -256,7 +256,7 @@
return fseek64(fp, offset, whence);
#elif defined(__BEOS__)
return _fseek(fp, offset, whence);
-#elif defined(HAVE_LARGEFILE_SUPPORT) && SIZEOF_FPOS_T >= 8
+#elif defined(HAVE_LARGEFILE_SUPPORT) && SIZEOF_FPOS_T >= 8
/* lacking a 64-bit capable fseek() (as Win64 does) use a 64-bit capable
fsetpos() and tell() to implement fseek()*/
fpos_t pos;
@@ -287,7 +287,7 @@
/* a portable ftell() function
Return -1 on failure with errno set appropriately, current file
position on success */
-#if defined(HAVE_LARGEFILE_SUPPORT) && SIZEOF_OFF_T < 8 && SIZEOF_FPOS_T >= 8
+#if defined(HAVE_LARGEFILE_SUPPORT) && SIZEOF_OFF_T < 8 && SIZEOF_FPOS_T >= 8
fpos_t
#else
off_t
@@ -314,13 +314,13 @@
{
int whence;
int ret;
-#if defined(HAVE_LARGEFILE_SUPPORT) && SIZEOF_OFF_T < 8 && SIZEOF_FPOS_T >= 8
+#if defined(HAVE_LARGEFILE_SUPPORT) && SIZEOF_OFF_T < 8 && SIZEOF_FPOS_T >= 8
fpos_t offset, pos;
#else
off_t offset;
#endif /* !MS_WIN64 */
PyObject *offobj;
-
+
if (f->f_fp == NULL)
return err_closed();
whence = 0;
@@ -334,7 +334,7 @@
#endif
if (PyErr_Occurred())
return NULL;
-
+
Py_BEGIN_ALLOW_THREADS
errno = 0;
ret = _portable_fseek(f->f_fp, offset, whence);
@@ -355,13 +355,13 @@
file_truncate(PyFileObject *f, PyObject *args)
{
int ret;
-#if defined(HAVE_LARGEFILE_SUPPORT) && SIZEOF_OFF_T < 8 && SIZEOF_FPOS_T >= 8
+#if defined(HAVE_LARGEFILE_SUPPORT) && SIZEOF_OFF_T < 8 && SIZEOF_FPOS_T >= 8
fpos_t newsize;
#else
off_t newsize;
#endif
PyObject *newsizeobj;
-
+
if (f->f_fp == NULL)
return err_closed();
newsizeobj = NULL;
@@ -416,7 +416,7 @@
Py_END_ALLOW_THREADS
if (ret != 0) goto onioerror;
#endif /* !MS_WIN32 */
-
+
Py_INCREF(Py_None);
return Py_None;
@@ -430,7 +430,7 @@
static PyObject *
file_tell(PyFileObject *f, PyObject *args)
{
-#if defined(HAVE_LARGEFILE_SUPPORT) && SIZEOF_OFF_T < 8 && SIZEOF_FPOS_T >= 8
+#if defined(HAVE_LARGEFILE_SUPPORT) && SIZEOF_OFF_T < 8 && SIZEOF_FPOS_T >= 8
fpos_t pos;
#else
off_t pos;
@@ -470,7 +470,7 @@
file_flush(PyFileObject *f, PyObject *args)
{
int res;
-
+
if (f->f_fp == NULL)
return err_closed();
if (!PyArg_NoArgs(args))
@@ -559,7 +559,7 @@
long bytesrequested = -1;
size_t bytesread, buffersize, chunksize;
PyObject *v;
-
+
if (f->f_fp == NULL)
return err_closed();
if (!PyArg_ParseTuple(args, "|l:read", &bytesrequested))
@@ -610,7 +610,7 @@
{
char *ptr;
size_t ntodo, ndone, nnow;
-
+
if (f->f_fp == NULL)
return err_closed();
if (!PyArg_Parse(args, "w#", &ptr, &ntodo))
@@ -634,6 +634,170 @@
return PyInt_FromLong((long)ndone);
}
+/**************************************************************************
+Win32 MS routine to get next line.
+
+Under MSVC 6:
+
++ MS threadsafe getc is very slow (multiple layers of function calls
+ before+after each character, to lock+unlock the stream).
++ The stream-locking functions are MS-internal -- can't access them
+ from user code.
++ There's nothing Tim could find in the MS C or platform SDK libraries
+ that can worm around this.
++ MS fgets locks/unlocks only once per line; it's the only hook we have.
+
+So we use fgets for speed(!), despite that it's painful.
+
+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 how MSVC 6 works internally.
+They seem to be relatively safe cheats, but we should expect this code
+to break someday.
+**************************************************************************/
+
+/* if Win32 and MS's compiler */
+#if defined(MS_WIN32) && defined(_MSC_VER)
+#define USE_MS_GETLINE_HACK
+#endif
+
+#ifdef USE_MS_GETLINE_HACK
+static PyObject*
+ms_getline_hack(FILE *fp)
+{
+#define INITBUFSIZE 100
+#define INCBUFSIZE 1000
+ PyObject* v; /* the string object result */
+ size_t total_v_size; /* total # chars in v's buffer */
+ char* pvfree; /* address of next free slot */
+ char* pvend; /* address one beyond last free slot */
+ char* p; /* temp */
+
+ if (fp->_cnt > 0) { /* HACK: "_cnt" isn't advertised */
+ /* optimize for normal case: something sitting in the
+ * buffer ready to go; avoid thread fiddling & realloc
+ * if possible
+ */
+ char msbuf[INITBUFSIZE];
+ memset(msbuf, '\n', INITBUFSIZE);
+ p = fgets(msbuf, INITBUFSIZE, fp);
+ /* since we didn't lock the file, there's no guarantee
+ * anything was still in the buffer
+ */
+ if (p == NULL) {
+ clearerr(fp);
+ if (PyErr_CheckSignals())
+ return NULL;
+ v = PyString_FromStringAndSize("", 0);
+ return v;
+ }
+ /* fgets read *something* */
+ p = memchr(msbuf, '\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 it's from fgets a \0 must be next.
+ * But if that's so, it 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;
+ if (p+1 < pvend && *(p+1) == '\0') {
+ /* it's from fgets: we win! */
+ v = PyString_FromStringAndSize(msbuf,
+ p - msbuf + 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);
+ 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');
+ 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);
+ pvfree = BUF(v) + INITBUFSIZE - 1;
+ }
+ else {
+ /* The stream isn't ready or isn't buffered. */
+ v = PyString_FromStringAndSize((char*)NULL, INITBUFSIZE);
+ if (v == NULL)
+ return v;
+ total_v_size = INITBUFSIZE;
+ pvfree = BUF(v);
+ }
+
+ /* Keep reading stuff into v; if it ever ends successfully, break
+ * after setting p one beyond the end of the line.
+ */
+ for (;;) {
+ size_t nfree;
+
+ Py_BEGIN_ALLOW_THREADS
+ pvend = BUF(v) + total_v_size;
+ nfree = pvend - pvfree;
+ memset(pvfree, '\n', nfree);
+ p = fgets(pvfree, nfree, fp);
+ Py_END_ALLOW_THREADS
+
+ if (p == NULL) {
+ clearerr(fp);
+ if (PyErr_CheckSignals()) {
+ Py_DECREF(v);
+ return NULL;
+ }
+ p = pvfree;
+ break;
+ }
+ /* See the "normal case" comments above for details. */
+ p = memchr(pvfree, '\n', nfree);
+ if (p != NULL) {
+ if (p+1 < pvend && *(p+1) == '\0') {
+ /* \n came from fgets */
+ ++p;
+ break;
+ }
+ /* \n came from us; last line of file, no newline */
+ assert(p > pvfree && *(p-1) == '\0');
+ --p;
+ break;
+ }
+ /* expand buffer and try again */
+ assert(*(pvend-1) == '\0');
+ total_v_size += INCBUFSIZE;
+ if (total_v_size > INT_MAX) {
+ PyErr_SetString(PyExc_OverflowError,
+ "line is longer than a Python string can hold");
+ Py_DECREF(v);
+ return NULL;
+ }
+ if (_PyString_Resize(&v, (int)total_v_size) < 0)
+ return NULL;
+ /* overwrite the trailing null byte */
+ pvfree = BUF(v) + (total_v_size - INCBUFSIZE - 1);
+ }
+ if (BUF(v) + total_v_size != p)
+ _PyString_Resize(&v, p - BUF(v));
+ return v;
+#undef INITBUFSIZE
+#undef INCBUFSIZE
+}
+#endif /* ifdef USE_MS_GETLINE_HACK */
/* Internal routine to get a line.
Size argument interpretation:
@@ -661,6 +825,10 @@
size_t n1, n2;
PyObject *v;
+#ifdef USE_MS_GETLINE_HACK
+ if (n == 0)
+ return ms_getline_hack(fp);
+#endif
n2 = n > 0 ? n : 100;
v = PyString_FromStringAndSize((char *)NULL, n2);
if (v == NULL)
@@ -695,6 +863,7 @@
if (n2 > INT_MAX) {
PyErr_SetString(PyExc_OverflowError,
"line is longer than a Python string can hold");
+ Py_DECREF(v);
return NULL;
}
if (_PyString_Resize(&v, n2) < 0)
@@ -999,7 +1168,7 @@
if (!PyString_Check(v)) {
const char *buffer;
int len;
- if (((f->f_binary &&
+ if (((f->f_binary &&
PyObject_AsReadBuffer(v,
(const void**)&buffer,
&len)) ||
@@ -1255,7 +1424,7 @@
Py_DECREF(meth);
if (fno == NULL)
return -1;
-
+
if (PyInt_Check(fno)) {
fd = PyInt_AsLong(fno);
Py_DECREF(fno);