Issue #14744: Use the new _PyUnicodeWriter internal API to speed up str%args and str.format(args)

* Formatting string, int, float and complex use the _PyUnicodeWriter API. It
   avoids a temporary buffer in most cases.
 * Add _PyUnicodeWriter_WriteStr() to restore the PyAccu optimization: just
   keep a reference to the string if the output is only composed of one string
 * Disable overallocation when formatting the last argument of str%args and
   str.format(args)
 * Overallocation allocates at least 100 characters: add min_length attribute
   to the _PyUnicodeWriter structure
 * Add new private functions: _PyUnicode_FastCopyCharacters(),
   _PyUnicode_FastFill() and _PyUnicode_FromASCII()

The speed up is around 20% in average.
This commit is contained in:
Victor Stinner 2012-05-29 12:57:52 +02:00
parent a1b0c9fc4d
commit d3f0882dfb
12 changed files with 878 additions and 437 deletions

View file

@ -648,8 +648,20 @@ PyAPI_FUNC(Py_ssize_t) PyUnicode_CopyCharacters(
Py_ssize_t from_start,
Py_ssize_t how_many
);
/* Unsafe version of PyUnicode_CopyCharacters(): don't check arguments and so
may crash if parameters are invalid (e.g. if the output string
is too short). */
PyAPI_FUNC(void) _PyUnicode_FastCopyCharacters(
PyObject *to,
Py_ssize_t to_start,
PyObject *from,
Py_ssize_t from_start,
Py_ssize_t how_many
);
#endif
#ifndef Py_LIMITED_API
/* Fill a string with a character: write fill_char into
unicode[start:start+length].
@ -658,13 +670,21 @@ PyAPI_FUNC(Py_ssize_t) PyUnicode_CopyCharacters(
Return the number of written character, or return -1 and raise an exception
on error. */
#ifndef Py_LIMITED_API
PyAPI_FUNC(Py_ssize_t) PyUnicode_Fill(
PyObject *unicode,
Py_ssize_t start,
Py_ssize_t length,
Py_UCS4 fill_char
);
/* Unsafe version of PyUnicode_Fill(): don't check arguments and so may crash
if parameters are invalid (e.g. if length is longer than the string). */
PyAPI_FUNC(void) _PyUnicode_FastFill(
PyObject *unicode,
Py_ssize_t start,
Py_ssize_t length,
Py_UCS4 fill_char
);
#endif
/* Create a Unicode Object from the Py_UNICODE buffer u of the given
@ -696,13 +716,19 @@ PyAPI_FUNC(PyObject*) PyUnicode_FromString(
const char *u /* UTF-8 encoded string */
);
#ifndef Py_LIMITED_API
/* Create a new string from a buffer of Py_UCS1, Py_UCS2 or Py_UCS4 characters.
Scan the string to find the maximum character. */
#ifndef Py_LIMITED_API
PyAPI_FUNC(PyObject*) PyUnicode_FromKindAndData(
int kind,
const void *buffer,
Py_ssize_t size);
/* Create a new string from a buffer of ASCII characters.
WARNING: Don't check if the string contains any non-ASCII character. */
PyAPI_FUNC(PyObject*) _PyUnicode_FromASCII(
const char *buffer,
Py_ssize_t size);
#endif
PyAPI_FUNC(PyObject*) PyUnicode_Substring(
@ -864,13 +890,70 @@ PyAPI_FUNC(PyObject *) PyUnicode_FromFormat(
...
);
#ifndef Py_LIMITED_API
typedef struct {
PyObject *buffer;
void *data;
enum PyUnicode_Kind kind;
Py_UCS4 maxchar;
Py_ssize_t size;
Py_ssize_t pos;
/* minimum length of the buffer when overallocation is enabled,
see _PyUnicodeWriter_Init() */
Py_ssize_t min_length;
struct {
unsigned char overallocate:1;
/* If readonly is 1, buffer is a shared string (cannot be modified)
and size is set to 0. */
unsigned char readonly:1;
} flags;
} _PyUnicodeWriter ;
/* Initialize a Unicode writer.
If min_length is greater than zero, _PyUnicodeWriter_Prepare()
overallocates the buffer and min_length is the minimum length in characters
of the buffer. */
PyAPI_FUNC(void)
_PyUnicodeWriter_Init(_PyUnicodeWriter *writer, Py_ssize_t min_length);
/* Prepare the buffer to write 'length' characters
with the specified maximum character.
Return 0 on success, raise an exception and return -1 on error. */
#define _PyUnicodeWriter_Prepare(WRITER, LENGTH, MAXCHAR) \
(((MAXCHAR) <= (WRITER)->maxchar \
&& (LENGTH) <= (WRITER)->size - (WRITER)->pos) \
? 0 \
: (((LENGTH) == 0) \
? 0 \
: _PyUnicodeWriter_PrepareInternal((WRITER), (LENGTH), (MAXCHAR))))
/* Don't call this function directly, use the _PyUnicodeWriter_Prepare() macro
instead. */
PyAPI_FUNC(int)
_PyUnicodeWriter_PrepareInternal(_PyUnicodeWriter *writer,
Py_ssize_t length, Py_UCS4 maxchar);
PyAPI_FUNC(int)
_PyUnicodeWriter_WriteStr(_PyUnicodeWriter *writer, PyObject *str);
PyAPI_FUNC(PyObject *)
_PyUnicodeWriter_Finish(_PyUnicodeWriter *writer);
PyAPI_FUNC(void)
_PyUnicodeWriter_Dealloc(_PyUnicodeWriter *writer);
#endif
#ifndef Py_LIMITED_API
/* Format the object based on the format_spec, as defined in PEP 3101
(Advanced String Formatting). */
PyAPI_FUNC(PyObject *) _PyUnicode_FormatAdvanced(PyObject *obj,
PyObject *format_spec,
Py_ssize_t start,
Py_ssize_t end);
PyAPI_FUNC(int) _PyUnicode_FormatAdvancedWriter(
_PyUnicodeWriter *writer,
PyObject *obj,
PyObject *format_spec,
Py_ssize_t start,
Py_ssize_t end);
#endif
PyAPI_FUNC(void) PyUnicode_InternInPlace(PyObject **);