Mercurial > hg
view mercurial/base85.c @ 18604:a1141f04e368
manifest: use a size 3 LRU cache to store parsed manifests
Previously, the manifest cache would store the last manifest parsed. We could
run into situations with operations like update where we would try parsing the
manifest for a revision r1, then r2, then r1 again. This increases the cache
size to 3 to avoid that bit of performance fragility.
author | Siddharth Agarwal <sid0@fb.com> |
---|---|
date | Sat, 09 Feb 2013 15:43:02 +0000 |
parents | 19a915d43a68 |
children | c1aefe57cf4e |
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/* base85 codec Copyright 2006 Brendan Cully <brendan@kublai.com> This software may be used and distributed according to the terms of the GNU General Public License, incorporated herein by reference. Largely based on git's implementation */ #define PY_SSIZE_T_CLEAN #include <Python.h> #include "util.h" static const char b85chars[] = "0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZ" "abcdefghijklmnopqrstuvwxyz!#$%&()*+-;<=>?@^_`{|}~"; static char b85dec[256]; static void b85prep(void) { int i; memset(b85dec, 0, sizeof(b85dec)); for (i = 0; i < sizeof(b85chars); i++) b85dec[(int)(b85chars[i])] = i + 1; } static PyObject * b85encode(PyObject *self, PyObject *args) { const unsigned char *text; PyObject *out; char *dst; Py_ssize_t len, olen, i; unsigned int acc, val, ch; int pad = 0; if (!PyArg_ParseTuple(args, "s#|i", &text, &len, &pad)) return NULL; if (pad) olen = ((len + 3) / 4 * 5) - 3; else { olen = len % 4; if (olen) olen++; olen += len / 4 * 5; } if (!(out = PyBytes_FromStringAndSize(NULL, olen + 3))) return NULL; dst = PyBytes_AsString(out); while (len) { acc = 0; for (i = 24; i >= 0; i -= 8) { ch = *text++; acc |= ch << i; if (--len == 0) break; } for (i = 4; i >= 0; i--) { val = acc % 85; acc /= 85; dst[i] = b85chars[val]; } dst += 5; } if (!pad) _PyBytes_Resize(&out, olen); return out; } static PyObject * b85decode(PyObject *self, PyObject *args) { PyObject *out; const char *text; char *dst; Py_ssize_t len, i, j, olen, cap; int c; unsigned int acc; if (!PyArg_ParseTuple(args, "s#", &text, &len)) return NULL; olen = len / 5 * 4; i = len % 5; if (i) olen += i - 1; if (!(out = PyBytes_FromStringAndSize(NULL, olen))) return NULL; dst = PyBytes_AsString(out); i = 0; while (i < len) { acc = 0; cap = len - i - 1; if (cap > 4) cap = 4; for (j = 0; j < cap; i++, j++) { c = b85dec[(int)*text++] - 1; if (c < 0) return PyErr_Format( PyExc_ValueError, "bad base85 character at position %d", (int)i); acc = acc * 85 + c; } if (i++ < len) { c = b85dec[(int)*text++] - 1; if (c < 0) return PyErr_Format( PyExc_ValueError, "bad base85 character at position %d", (int)i); /* overflow detection: 0xffffffff == "|NsC0", * "|NsC" == 0x03030303 */ if (acc > 0x03030303 || (acc *= 85) > 0xffffffff - c) return PyErr_Format( PyExc_ValueError, "bad base85 sequence at position %d", (int)i); acc += c; } cap = olen < 4 ? olen : 4; olen -= cap; for (j = 0; j < 4 - cap; j++) acc *= 85; if (cap && cap < 4) acc += 0xffffff >> (cap - 1) * 8; for (j = 0; j < cap; j++) { acc = (acc << 8) | (acc >> 24); *dst++ = acc; } } return out; } static char base85_doc[] = "Base85 Data Encoding"; static PyMethodDef methods[] = { {"b85encode", b85encode, METH_VARARGS, "Encode text in base85.\n\n" "If the second parameter is true, pad the result to a multiple of " "five characters.\n"}, {"b85decode", b85decode, METH_VARARGS, "Decode base85 text.\n"}, {NULL, NULL} }; #ifdef IS_PY3K static struct PyModuleDef base85_module = { PyModuleDef_HEAD_INIT, "base85", base85_doc, -1, methods }; PyMODINIT_FUNC PyInit_base85(void) { b85prep(); return PyModule_Create(&base85_module); } #else PyMODINIT_FUNC initbase85(void) { Py_InitModule3("base85", methods, base85_doc); b85prep(); } #endif