Mercurial > hg
view mercurial/cext/diffhelpers.c @ 33289:abd7dedbaa36
sparse: vendor Facebook-developed extension
Facebook has developed an extension to enable "sparse" checkouts -
a working directory with a subset of files. This feature is a critical
component in enabling repositories to scale to infinite number of
files while retaining reasonable performance. It's worth noting
that sparse checkout is only one possible solution to this problem:
another is virtual filesystems that realize files on first access.
But given that virtual filesystems may not be accessible to all
users, sparse checkout is necessary as a fallback.
Per mailing list discussion at
https://www.mercurial-scm.org/pipermail/mercurial-devel/2017-March/095868.html
we want to add sparse checkout to the Mercurial distribution via
roughly the following mechanism:
1. Vendor extension as-is with minimal modifications (this patch)
2. Refactor extension so it is more clearly experimental and inline
with Mercurial practices
3. Move code from extension into core where possible
4. Drop experimental labeling and/or move feature into core
after sign-off from narrow clone feature owners
This commit essentially copies the sparse extension and tests
from revision 71e0a2aeca92a4078fe1b8c76e32c88ff1929737 of the
https://bitbucket.org/facebook/hg-experimental repository.
A list of modifications made as part of vendoring is as follows:
* "EXPERIMENTAL" added to module docstring
* Imports were changed to match Mercurial style conventions
* "testedwith" value was updated to core Mercurial special value and
comment boilerplate was inserted
* A "clone_sparse" function was renamed to "clonesparse" to appease
the style checker
* Paths to the sparse extension in tests reflect built-in location
* test-sparse-extensions.t was renamed to test-sparse-fsmonitor.t
and references to "simplecache" were removed. The test always skips
because it isn't trivial to run it given the way we currently run
fsmonitor tests
* A double empty line was removed from test-sparse-profiles.t
There are aspects of the added code that are obviously not ideal.
The goal is to make a minimal number of modifications as part of
the vendoring to make it easier to track changes from the original
implementation. Refactoring will occur in subsequent patches.
author | Gregory Szorc <gregory.szorc@gmail.com> |
---|---|
date | Sat, 01 Jul 2017 10:43:29 -0700 |
parents | 017ad85e5ac8 |
children | 7f8338b87c88 |
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/* * diffhelpers.c - helper routines for mpatch * * Copyright 2007 Chris Mason <chris.mason@oracle.com> * * This software may be used and distributed according to the terms * of the GNU General Public License v2, incorporated herein by reference. */ #include <Python.h> #include <stdlib.h> #include <string.h> #include "util.h" static char diffhelpers_doc[] = "Efficient diff parsing"; static PyObject *diffhelpers_Error; /* fixup the last lines of a and b when the patch has no newline at eof */ static void _fix_newline(PyObject *hunk, PyObject *a, PyObject *b) { Py_ssize_t hunksz = PyList_Size(hunk); PyObject *s = PyList_GET_ITEM(hunk, hunksz-1); char *l = PyBytes_AsString(s); Py_ssize_t alen = PyList_Size(a); Py_ssize_t blen = PyList_Size(b); char c = l[0]; PyObject *hline; Py_ssize_t sz = PyBytes_GET_SIZE(s); if (sz > 1 && l[sz-2] == '\r') /* tolerate CRLF in last line */ sz -= 1; hline = PyBytes_FromStringAndSize(l, sz-1); if (!hline) { return; } if (c == ' ' || c == '+') { PyObject *rline = PyBytes_FromStringAndSize(l + 1, sz - 2); PyList_SetItem(b, blen-1, rline); } if (c == ' ' || c == '-') { Py_INCREF(hline); PyList_SetItem(a, alen-1, hline); } PyList_SetItem(hunk, hunksz-1, hline); } /* python callable form of _fix_newline */ static PyObject * fix_newline(PyObject *self, PyObject *args) { PyObject *hunk, *a, *b; if (!PyArg_ParseTuple(args, "OOO", &hunk, &a, &b)) return NULL; _fix_newline(hunk, a, b); return Py_BuildValue("l", 0); } #if (PY_VERSION_HEX < 0x02050000) static const char *addlines_format = "OOiiOO"; #else static const char *addlines_format = "OOnnOO"; #endif /* * read lines from fp into the hunk. The hunk is parsed into two arrays * a and b. a gets the old state of the text, b gets the new state * The control char from the hunk is saved when inserting into a, but not b * (for performance while deleting files) */ static PyObject * addlines(PyObject *self, PyObject *args) { PyObject *fp, *hunk, *a, *b, *x; Py_ssize_t i; Py_ssize_t lena, lenb; Py_ssize_t num; Py_ssize_t todoa, todob; char *s, c; PyObject *l; if (!PyArg_ParseTuple(args, addlines_format, &fp, &hunk, &lena, &lenb, &a, &b)) return NULL; while (1) { todoa = lena - PyList_Size(a); todob = lenb - PyList_Size(b); num = todoa > todob ? todoa : todob; if (num == 0) break; for (i = 0; i < num; i++) { x = PyFile_GetLine(fp, 0); s = PyBytes_AsString(x); c = *s; if (strcmp(s, "\\ No newline at end of file\n") == 0) { _fix_newline(hunk, a, b); continue; } if (c == '\n') { /* Some patches may be missing the control char * on empty lines. Supply a leading space. */ Py_DECREF(x); x = PyBytes_FromString(" \n"); } PyList_Append(hunk, x); if (c == '+') { l = PyBytes_FromString(s + 1); PyList_Append(b, l); Py_DECREF(l); } else if (c == '-') { PyList_Append(a, x); } else { l = PyBytes_FromString(s + 1); PyList_Append(b, l); Py_DECREF(l); PyList_Append(a, x); } Py_DECREF(x); } } return Py_BuildValue("l", 0); } /* * compare the lines in a with the lines in b. a is assumed to have * a control char at the start of each line, this char is ignored in the * compare */ static PyObject * testhunk(PyObject *self, PyObject *args) { PyObject *a, *b; long bstart; Py_ssize_t alen, blen; Py_ssize_t i; char *sa, *sb; if (!PyArg_ParseTuple(args, "OOl", &a, &b, &bstart)) return NULL; alen = PyList_Size(a); blen = PyList_Size(b); if (alen > blen - bstart || bstart < 0) { return Py_BuildValue("l", -1); } for (i = 0; i < alen; i++) { sa = PyBytes_AsString(PyList_GET_ITEM(a, i)); sb = PyBytes_AsString(PyList_GET_ITEM(b, i + bstart)); if (strcmp(sa + 1, sb) != 0) return Py_BuildValue("l", -1); } return Py_BuildValue("l", 0); } static PyMethodDef methods[] = { {"addlines", addlines, METH_VARARGS, "add lines to a hunk\n"}, {"fix_newline", fix_newline, METH_VARARGS, "fixup newline counters\n"}, {"testhunk", testhunk, METH_VARARGS, "test lines in a hunk\n"}, {NULL, NULL} }; static const int version = 1; #ifdef IS_PY3K static struct PyModuleDef diffhelpers_module = { PyModuleDef_HEAD_INIT, "diffhelpers", diffhelpers_doc, -1, methods }; PyMODINIT_FUNC PyInit_diffhelpers(void) { PyObject *m; m = PyModule_Create(&diffhelpers_module); if (m == NULL) return NULL; diffhelpers_Error = PyErr_NewException("diffhelpers.diffhelpersError", NULL, NULL); Py_INCREF(diffhelpers_Error); PyModule_AddObject(m, "diffhelpersError", diffhelpers_Error); PyModule_AddIntConstant(m, "version", version); return m; } #else PyMODINIT_FUNC initdiffhelpers(void) { PyObject *m; m = Py_InitModule3("diffhelpers", methods, diffhelpers_doc); diffhelpers_Error = PyErr_NewException("diffhelpers.diffhelpersError", NULL, NULL); PyModule_AddIntConstant(m, "version", version); } #endif