Mercurial > hg
view mercurial/dirs.c @ 31793:69d8fcf20014
help: document bundle specifications
I softly formalized the concept of a "bundle specification" a while
ago when I was working on clone bundles and stream clone bundles and
wanted a more robust way to define what exactly is in a bundle file.
The concept has existed for a while. Since it is part of the clone
bundles feature and exposed to the user via the "-t" argument to
`hg bundle`, it is something we need to support for the long haul.
After the 4.1 release, I heard a few people comment that they didn't
realize you could generate zstd bundles with `hg bundle`. I'm
partially to blame for not documenting it in bundle's docstring.
Additionally, I added a hacky, experimental feature for controlling
the compression level of bundles in 76104a4899ad. As the commit
message says, I went with a quick and dirty solution out of time
constraints. Furthermore, I wanted to eventually store this
configuration in the "bundlespec" so it could be made more flexible.
Given:
a) bundlespecs are here to stay
b) we don't have great documentation over what they are, despite being
a user-facing feature
c) the list of available compression engines and their behavior isn't
exposed
d) we need an extensible place to modify behavior of compression
engines
I want to move forward with formalizing bundlespecs as a user-facing
feature. This commit does that by introducing a "bundlespec" help
page. Leaning on the just-added compression engine documentation
and API, the topic also conveniently lists available compression
engines and details about them. This makes features like zstd
bundle compression more discoverable. e.g. you can now
`hg help -k zstd` and it lists the "bundlespec" topic.
author | Gregory Szorc <gregory.szorc@gmail.com> |
---|---|
date | Sat, 01 Apr 2017 13:42:06 -0700 |
parents | 1e5ff5ae1d2b |
children |
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/* dirs.c - dynamic directory diddling for dirstates Copyright 2013 Facebook This software may be used and distributed according to the terms of the GNU General Public License, incorporated herein by reference. */ #define PY_SSIZE_T_CLEAN #include <Python.h> #include "util.h" #ifdef IS_PY3K #define PYLONG_VALUE(o) ((PyLongObject *)o)->ob_digit[1] #else #define PYLONG_VALUE(o) PyInt_AS_LONG(o) #endif /* * This is a multiset of directory names, built from the files that * appear in a dirstate or manifest. * * A few implementation notes: * * We modify Python integers for refcounting, but those integers are * never visible to Python code. * * We mutate strings in-place, but leave them immutable once they can * be seen by Python code. */ typedef struct { PyObject_HEAD PyObject *dict; } dirsObject; static inline Py_ssize_t _finddir(const char *path, Py_ssize_t pos) { while (pos != -1) { if (path[pos] == '/') break; pos -= 1; } return pos; } static int _addpath(PyObject *dirs, PyObject *path) { const char *cpath = PyBytes_AS_STRING(path); Py_ssize_t pos = PyBytes_GET_SIZE(path); PyObject *key = NULL; int ret = -1; /* This loop is super critical for performance. That's why we inline * access to Python structs instead of going through a supported API. * The implementation, therefore, is heavily dependent on CPython * implementation details. We also commit violations of the Python * "protocol" such as mutating immutable objects. But since we only * mutate objects created in this function or in other well-defined * locations, the references are known so these violations should go * unnoticed. The code for adjusting the length of a PyBytesObject is * essentially a minimal version of _PyBytes_Resize. */ while ((pos = _finddir(cpath, pos - 1)) != -1) { PyObject *val; /* It's likely that every prefix already has an entry in our dict. Try to avoid allocating and deallocating a string for each prefix we check. */ if (key != NULL) ((PyBytesObject *)key)->ob_shash = -1; else { /* Force Python to not reuse a small shared string. */ key = PyBytes_FromStringAndSize(cpath, pos < 2 ? 2 : pos); if (key == NULL) goto bail; } /* Py_SIZE(o) refers to the ob_size member of the struct. Yes, * assigning to what looks like a function seems wrong. */ Py_SIZE(key) = pos; ((PyBytesObject *)key)->ob_sval[pos] = '\0'; val = PyDict_GetItem(dirs, key); if (val != NULL) { PYLONG_VALUE(val) += 1; break; } /* Force Python to not reuse a small shared int. */ #ifdef IS_PY3K val = PyLong_FromLong(0x1eadbeef); #else val = PyInt_FromLong(0x1eadbeef); #endif if (val == NULL) goto bail; PYLONG_VALUE(val) = 1; ret = PyDict_SetItem(dirs, key, val); Py_DECREF(val); if (ret == -1) goto bail; Py_CLEAR(key); } ret = 0; bail: Py_XDECREF(key); return ret; } static int _delpath(PyObject *dirs, PyObject *path) { char *cpath = PyBytes_AS_STRING(path); Py_ssize_t pos = PyBytes_GET_SIZE(path); PyObject *key = NULL; int ret = -1; while ((pos = _finddir(cpath, pos - 1)) != -1) { PyObject *val; key = PyBytes_FromStringAndSize(cpath, pos); if (key == NULL) goto bail; val = PyDict_GetItem(dirs, key); if (val == NULL) { PyErr_SetString(PyExc_ValueError, "expected a value, found none"); goto bail; } if (--PYLONG_VALUE(val) <= 0) { if (PyDict_DelItem(dirs, key) == -1) goto bail; } else break; Py_CLEAR(key); } ret = 0; bail: Py_XDECREF(key); return ret; } static int dirs_fromdict(PyObject *dirs, PyObject *source, char skipchar) { PyObject *key, *value; Py_ssize_t pos = 0; while (PyDict_Next(source, &pos, &key, &value)) { if (!PyBytes_Check(key)) { PyErr_SetString(PyExc_TypeError, "expected string key"); return -1; } if (skipchar) { if (!dirstate_tuple_check(value)) { PyErr_SetString(PyExc_TypeError, "expected a dirstate tuple"); return -1; } if (((dirstateTupleObject *)value)->state == skipchar) continue; } if (_addpath(dirs, key) == -1) return -1; } return 0; } static int dirs_fromiter(PyObject *dirs, PyObject *source) { PyObject *iter, *item = NULL; int ret; iter = PyObject_GetIter(source); if (iter == NULL) return -1; while ((item = PyIter_Next(iter)) != NULL) { if (!PyBytes_Check(item)) { PyErr_SetString(PyExc_TypeError, "expected string"); break; } if (_addpath(dirs, item) == -1) break; Py_CLEAR(item); } ret = PyErr_Occurred() ? -1 : 0; Py_DECREF(iter); Py_XDECREF(item); return ret; } /* * Calculate a refcounted set of directory names for the files in a * dirstate. */ static int dirs_init(dirsObject *self, PyObject *args) { PyObject *dirs = NULL, *source = NULL; char skipchar = 0; int ret = -1; self->dict = NULL; if (!PyArg_ParseTuple(args, "|Oc:__init__", &source, &skipchar)) return -1; dirs = PyDict_New(); if (dirs == NULL) return -1; if (source == NULL) ret = 0; else if (PyDict_Check(source)) ret = dirs_fromdict(dirs, source, skipchar); else if (skipchar) PyErr_SetString(PyExc_ValueError, "skip character is only supported " "with a dict source"); else ret = dirs_fromiter(dirs, source); if (ret == -1) Py_XDECREF(dirs); else self->dict = dirs; return ret; } PyObject *dirs_addpath(dirsObject *self, PyObject *args) { PyObject *path; if (!PyArg_ParseTuple(args, "O!:addpath", &PyBytes_Type, &path)) return NULL; if (_addpath(self->dict, path) == -1) return NULL; Py_RETURN_NONE; } static PyObject *dirs_delpath(dirsObject *self, PyObject *args) { PyObject *path; if (!PyArg_ParseTuple(args, "O!:delpath", &PyBytes_Type, &path)) return NULL; if (_delpath(self->dict, path) == -1) return NULL; Py_RETURN_NONE; } static int dirs_contains(dirsObject *self, PyObject *value) { return PyBytes_Check(value) ? PyDict_Contains(self->dict, value) : 0; } static void dirs_dealloc(dirsObject *self) { Py_XDECREF(self->dict); PyObject_Del(self); } static PyObject *dirs_iter(dirsObject *self) { return PyObject_GetIter(self->dict); } static PySequenceMethods dirs_sequence_methods; static PyMethodDef dirs_methods[] = { {"addpath", (PyCFunction)dirs_addpath, METH_VARARGS, "add a path"}, {"delpath", (PyCFunction)dirs_delpath, METH_VARARGS, "remove a path"}, {NULL} /* Sentinel */ }; static PyTypeObject dirsType = { PyVarObject_HEAD_INIT(NULL, 0) }; void dirs_module_init(PyObject *mod) { dirs_sequence_methods.sq_contains = (objobjproc)dirs_contains; dirsType.tp_name = "parsers.dirs"; dirsType.tp_new = PyType_GenericNew; dirsType.tp_basicsize = sizeof(dirsObject); dirsType.tp_dealloc = (destructor)dirs_dealloc; dirsType.tp_as_sequence = &dirs_sequence_methods; dirsType.tp_flags = Py_TPFLAGS_DEFAULT; dirsType.tp_doc = "dirs"; dirsType.tp_iter = (getiterfunc)dirs_iter; dirsType.tp_methods = dirs_methods; dirsType.tp_init = (initproc)dirs_init; if (PyType_Ready(&dirsType) < 0) return; Py_INCREF(&dirsType); PyModule_AddObject(mod, "dirs", (PyObject *)&dirsType); }