parsers: fix a memleak, and add a clearcaches method to the index

This change also fixes a nasty memory leak: previously, self->caches
was not being freed.

The new clearcaches method lets us benchmark with finer granularity,
as it lets us separate the cost of loading a revlog index from those
of populating and accessing the cache data structures.

mercurial/parsers.c

@@ -1,720 +1,740 b''
 /*
  parsers.c - efficient content parsing
 
  Copyright 2008 Matt Mackall <[e-mail]> and others
 
  This software may be used and distributed according to the terms of
  the GNU General Public License, incorporated herein by reference.
 */
 
 #include <Python.h>
 #include <ctype.h>
 #include <string.h>
 
 #include "util.h"
 
 static int hexdigit(char c)
 {
 	if (c >= '0' && c <= '9')
 		return c - '0';
 	if (c >= 'a' && c <= 'f')
 		return c - 'a' + 10;
 	if (c >= 'A' && c <= 'F')
 		return c - 'A' + 10;
 
 	PyErr_SetString(PyExc_ValueError, "input contains non-hex character");
 	return 0;
 }
 
 /*
  * Turn a hex-encoded string into binary.
  */
 static PyObject *unhexlify(const char *str, int len)
 {
 	PyObject *ret;
 	const char *c;
 	char *d;
 
 	ret = PyBytes_FromStringAndSize(NULL, len / 2);
 
 	if (!ret)
 		return NULL;
 
 	d = PyBytes_AsString(ret);
 
 	for (c = str; c < str + len;) {
 		int hi = hexdigit(*c++);
 		int lo = hexdigit(*c++);
 		*d++ = (hi << 4) | lo;
 	}
 
 	return ret;
 }
 
 /*
  * This code assumes that a manifest is stitched together with newline
  * ('\n') characters.
  */
 static PyObject *parse_manifest(PyObject *self, PyObject *args)
 {
 	PyObject *mfdict, *fdict;
 	char *str, *cur, *start, *zero;
 	int len;
 
 	if (!PyArg_ParseTuple(args, "O!O!s#:parse_manifest",
 			      &PyDict_Type, &mfdict,
 			      &PyDict_Type, &fdict,
 			      &str, &len))
 		goto quit;
 
 	for (start = cur = str, zero = NULL; cur < str + len; cur++) {
 		PyObject *file = NULL, *node = NULL;
 		PyObject *flags = NULL;
 		int nlen;
 
 		if (!*cur) {
 			zero = cur;
 			continue;
 		}
 		else if (*cur != '\n')
 			continue;
 
 		if (!zero) {
 			PyErr_SetString(PyExc_ValueError,
 					"manifest entry has no separator");
 			goto quit;
 		}
 
 		file = PyBytes_FromStringAndSize(start, zero - start);
 
 		if (!file)
 			goto bail;
 
 		nlen = cur - zero - 1;
 
 		node = unhexlify(zero + 1, nlen > 40 ? 40 : nlen);
 		if (!node)
 			goto bail;
 
 		if (nlen > 40) {
 			flags = PyBytes_FromStringAndSize(zero + 41,
 							   nlen - 40);
 			if (!flags)
 				goto bail;
 
 			if (PyDict_SetItem(fdict, file, flags) == -1)
 				goto bail;
 		}
 
 		if (PyDict_SetItem(mfdict, file, node) == -1)
 			goto bail;
 
 		start = cur + 1;
 		zero = NULL;
 
 		Py_XDECREF(flags);
 		Py_XDECREF(node);
 		Py_XDECREF(file);
 		continue;
 	bail:
 		Py_XDECREF(flags);
 		Py_XDECREF(node);
 		Py_XDECREF(file);
 		goto quit;
 	}
 
 	if (len > 0 && *(cur - 1) != '\n') {
 		PyErr_SetString(PyExc_ValueError,
 				"manifest contains trailing garbage");
 		goto quit;
 	}
 
 	Py_INCREF(Py_None);
 	return Py_None;
 quit:
 	return NULL;
 }
 
 #ifdef _WIN32
 #ifdef _MSC_VER
 /* msvc 6.0 has problems */
 #define inline __inline
 typedef unsigned long uint32_t;
 typedef unsigned __int64 uint64_t;
 #else
 #include <stdint.h>
 #endif
 static uint32_t ntohl(uint32_t x)
 {
 	return ((x & 0x000000ffUL) << 24) |
 	       ((x & 0x0000ff00UL) <<  8) |
 	       ((x & 0x00ff0000UL) >>  8) |
 	       ((x & 0xff000000UL) >> 24);
 }
 #else
 /* not windows */
 #include <sys/types.h>
 #if defined __BEOS__ && !defined __HAIKU__
 #include <ByteOrder.h>
 #else
 #include <arpa/inet.h>
 #endif
 #include <inttypes.h>
 #endif
 
 static PyObject *parse_dirstate(PyObject *self, PyObject *args)
 {
 	PyObject *dmap, *cmap, *parents = NULL, *ret = NULL;
 	PyObject *fname = NULL, *cname = NULL, *entry = NULL;
 	char *str, *cur, *end, *cpos;
 	int state, mode, size, mtime;
 	unsigned int flen;
 	int len;
 	uint32_t decode[4]; /* for alignment */
 
 	if (!PyArg_ParseTuple(args, "O!O!s#:parse_dirstate",
 			      &PyDict_Type, &dmap,
 			      &PyDict_Type, &cmap,
 			      &str, &len))
 		goto quit;
 
 	/* read parents */
 	if (len < 40)
 		goto quit;
 
 	parents = Py_BuildValue("s#s#", str, 20, str + 20, 20);
 	if (!parents)
 		goto quit;
 
 	/* read filenames */
 	cur = str + 40;
 	end = str + len;
 
 	while (cur < end - 17) {
 		/* unpack header */
 		state = *cur;
 		memcpy(decode, cur + 1, 16);
 		mode = ntohl(decode[0]);
 		size = ntohl(decode[1]);
 		mtime = ntohl(decode[2]);
 		flen = ntohl(decode[3]);
 		cur += 17;
 		if (cur + flen > end || cur + flen < cur) {
 			PyErr_SetString(PyExc_ValueError, "overflow in dirstate");
 			goto quit;
 		}
 
 		entry = Py_BuildValue("ciii", state, mode, size, mtime);
 		if (!entry)
 			goto quit;
 		PyObject_GC_UnTrack(entry); /* don't waste time with this */
 
 		cpos = memchr(cur, 0, flen);
 		if (cpos) {
 			fname = PyBytes_FromStringAndSize(cur, cpos - cur);
 			cname = PyBytes_FromStringAndSize(cpos + 1,
 							   flen - (cpos - cur) - 1);
 			if (!fname || !cname ||
 			    PyDict_SetItem(cmap, fname, cname) == -1 ||
 			    PyDict_SetItem(dmap, fname, entry) == -1)
 				goto quit;
 			Py_DECREF(cname);
 		} else {
 			fname = PyBytes_FromStringAndSize(cur, flen);
 			if (!fname ||
 			    PyDict_SetItem(dmap, fname, entry) == -1)
 				goto quit;
 		}
 		cur += flen;
 		Py_DECREF(fname);
 		Py_DECREF(entry);
 		fname = cname = entry = NULL;
 	}
 
 	ret = parents;
 	Py_INCREF(ret);
 quit:
 	Py_XDECREF(fname);
 	Py_XDECREF(cname);
 	Py_XDECREF(entry);
 	Py_XDECREF(parents);
 	return ret;
 }
 
 /*
  * A list-like object that decodes the contents of a RevlogNG index
  * file on demand. It has limited support for insert and delete at the
  * last element before the end.  The last entry is always a sentinel
  * nullid.
  */
 typedef struct {
 	PyObject_HEAD
 	/* Type-specific fields go here. */
 	PyObject *data;        /* raw bytes of index */
 	PyObject **cache;      /* cached tuples */
 	const char **offsets;  /* populated on demand */
 	Py_ssize_t raw_length; /* original number of elements */
 	Py_ssize_t length;     /* current number of elements */
 	PyObject *added;       /* populated on demand */
 	int inlined;
 } indexObject;
 
 static Py_ssize_t index_length(indexObject *self)
 {
 	if (self->added == NULL)
 		return self->length;
 	return self->length + PyList_GET_SIZE(self->added);
 }
 
 static PyObject *nullentry;
 
 static long inline_scan(indexObject *self, const char **offsets);
 
 #if LONG_MAX == 0x7fffffffL
 static const char *tuple_format = "Kiiiiiis#";
 #else
 static const char *tuple_format = "kiiiiiis#";
 #endif
 
 /* RevlogNG format (all in big endian, data may be inlined):
  *    6 bytes: offset
  *    2 bytes: flags
  *    4 bytes: compressed length
  *    4 bytes: uncompressed length
  *    4 bytes: base revision
  *    4 bytes: link revision
  *    4 bytes: parent 1 revision
  *    4 bytes: parent 2 revision
  *   32 bytes: nodeid (only 20 bytes used)
  */
 static PyObject *index_get(indexObject *self, Py_ssize_t pos)
 {
 	uint32_t decode[8]; /* to enforce alignment with inline data */
 	uint64_t offset_flags;
 	int comp_len, uncomp_len, base_rev, link_rev, parent_1, parent_2;
 	const char *c_node_id;
 	const char *data;
 	Py_ssize_t length = index_length(self);
 	PyObject *entry;
 
 	if (pos >= length) {
 		PyErr_SetString(PyExc_IndexError, "revlog index out of range");
 		return NULL;
 	}
 
 	if (pos == length - 1) {
 		Py_INCREF(nullentry);
 		return nullentry;
 	}
 
 	if (pos >= self->length - 1) {
 		PyObject *obj;
 		obj = PyList_GET_ITEM(self->added, pos - self->length + 1);
 		Py_INCREF(obj);
 		return obj;
 	}
 
 	if (self->cache) {
 		if (self->cache[pos]) {
 			Py_INCREF(self->cache[pos]);
 			return self->cache[pos];
 		}
 	} else {
 		self->cache = calloc(self->raw_length, sizeof(PyObject *));
 		if (self->cache == NULL)
 			return PyErr_NoMemory();
 	}
 
 	if (self->inlined && pos > 0) {
 		if (self->offsets == NULL) {
 			self->offsets = malloc(self->raw_length *
 					       sizeof(*self->offsets));
 			if (self->offsets == NULL)
 				return PyErr_NoMemory();
 			inline_scan(self, self->offsets);
 		}
 		data = self->offsets[pos];
 	} else
 		data = PyString_AS_STRING(self->data) + pos * 64;
 
 	memcpy(decode, data, 8 * sizeof(uint32_t));
 
 	offset_flags = ntohl(decode[1]);
 	if (pos == 0) /* mask out version number for the first entry */
 		offset_flags &= 0xFFFF;
 	else {
 		uint32_t offset_high = ntohl(decode[0]);
 		offset_flags |= ((uint64_t)offset_high) << 32;
 	}
 
 	comp_len = ntohl(decode[2]);
 	uncomp_len = ntohl(decode[3]);
 	base_rev = ntohl(decode[4]);
 	link_rev = ntohl(decode[5]);
 	parent_1 = ntohl(decode[6]);
 	parent_2 = ntohl(decode[7]);
 	c_node_id = data + 32;
 
 	entry = Py_BuildValue(tuple_format, offset_flags, comp_len,
 			      uncomp_len, base_rev, link_rev,
 			      parent_1, parent_2, c_node_id, 20);
 
 	if (entry)
 		PyObject_GC_UnTrack(entry);
 
 	self->cache[pos] = entry;
 	Py_INCREF(entry);
 
 	return entry;
 }
 
 static PyObject *index_insert(indexObject *self, PyObject *args)
 {
 	PyObject *obj, *node;
 	long offset;
 	Py_ssize_t len;
 
 	if (!PyArg_ParseTuple(args, "lO", &offset, &obj))
 		return NULL;
 
 	if (!PyTuple_Check(obj) || PyTuple_GET_SIZE(obj) != 8) {
 		PyErr_SetString(PyExc_ValueError, "8-tuple required");
 		return NULL;
 	}
 
 	node = PyTuple_GET_ITEM(obj, 7);
 	if (!PyString_Check(node) || PyString_GET_SIZE(node) != 20) {
 		PyErr_SetString(PyExc_ValueError,
 				"20-byte hash required as last element");
 		return NULL;
 	}
 
 	len = index_length(self);
 
 	if (offset < 0)
 		offset += len;
 
 	if (offset != len - 1) {
 		PyErr_SetString(PyExc_IndexError,
 				"insert only supported at index -1");
 		return NULL;
 	}
 
 	if (self->added == NULL) {
 		self->added = PyList_New(0);
 		if (self->added == NULL)
 			return NULL;
 	}
 
 	if (PyList_Append(self->added, obj) == -1)
 		return NULL;
 
 	Py_RETURN_NONE;
 }
 
+static void _index_clearcaches(indexObject *self)
+{
+	if (self->cache) {
+		Py_ssize_t i;
+
+		for (i = 0; i < self->raw_length; i++) {
+			Py_XDECREF(self->cache[i]);
+			self->cache[i] = NULL;
+		}
+		free(self->cache);
+		self->cache = NULL;
+	}
+	if (self->offsets) {
+		free(self->offsets);
+		self->offsets = NULL;
+	}
+}
+
+static PyObject *index_clearcaches(indexObject *self)
+{
+	_index_clearcaches(self);
+	Py_RETURN_NONE;
+}
+
 static int index_assign_subscript(indexObject *self, PyObject *item,
 				  PyObject *value)
 {
 	Py_ssize_t start, stop, step, slicelength;
 	Py_ssize_t length = index_length(self);
 
 	if (!PySlice_Check(item) || value != NULL) {
 		PyErr_SetString(PyExc_TypeError,
 				"revlog index only supports slice deletion");
 		return -1;
 	}
 
 	if (PySlice_GetIndicesEx((PySliceObject*)item, length,
 				 &start, &stop, &step, &slicelength) < 0)
 		return -1;
 
 	if (slicelength <= 0)
 		return 0;
 
 	if ((step < 0 && start < stop) || (step > 0 && start > stop))
 		stop = start;
 
 	if (step < 0) {
 		stop = start + 1;
 		start = stop + step*(slicelength - 1) - 1;
 		step = -step;
 	}
 
 	if (step != 1) {
 		PyErr_SetString(PyExc_ValueError,
 				"revlog index delete requires step size of 1");
 		return -1;
 	}
 
 	if (stop != length - 1) {
 		PyErr_SetString(PyExc_IndexError,
 				"revlog index deletion indices are invalid");
 		return -1;
 	}
 
 	if (start < self->length) {
 		self->length = start + 1;
 		if (self->added) {
 			Py_DECREF(self->added);
 			self->added = NULL;
 		}
 		return 0;
 	}
 
 	return PyList_SetSlice(self->added, start - self->length + 1,
 			       PyList_GET_SIZE(self->added),
 			       NULL);
 }
 
 static long inline_scan(indexObject *self, const char **offsets)
 {
 	const char *data = PyString_AS_STRING(self->data);
 	const char *end = data + PyString_GET_SIZE(self->data);
 	const long hdrsize = 64;
 	long incr = hdrsize;
 	Py_ssize_t len = 0;
 
 	while (data + hdrsize <= end) {
 		uint32_t comp_len;
 		const char *old_data;
 		/* 3rd element of header is length of compressed inline data */
 		memcpy(&comp_len, data + 8, sizeof(uint32_t));
 		incr = hdrsize + ntohl(comp_len);
 		if (incr < hdrsize)
 			break;
 		if (offsets)
 			offsets[len] = data;
 		len++;
 		old_data = data;
 		data += incr;
 		if (data <= old_data)
 			break;
 	}
 
 	if (data != end && data + hdrsize != end) {
 		if (!PyErr_Occurred())
 			PyErr_SetString(PyExc_ValueError, "corrupt index file");
 		return -1;
 	}
 
 	return len;
 }
 
 static int index_real_init(indexObject *self, const char *data, int size,
 			   PyObject *inlined_obj, PyObject *data_obj)
 {
 	self->inlined = inlined_obj && PyObject_IsTrue(inlined_obj);
 	self->data = data_obj;
 	self->cache = NULL;
 
 	self->added = NULL;
 	self->offsets = NULL;
 	Py_INCREF(self->data);
 
 	if (self->inlined) {
 		long len = inline_scan(self, NULL);
 		if (len == -1)
 			goto bail;
 		self->raw_length = len;
 		self->length = len + 1;
 	} else {
 		if (size % 64) {
 			PyErr_SetString(PyExc_ValueError, "corrupt index file");
 			goto bail;
 		}
 		self->raw_length = size / 64;
 		self->length = self->raw_length + 1;
 	}
 
 	return 0;
 bail:
 	return -1;
 }
 
 static int index_init(indexObject *self, PyObject *args, PyObject *kwds)
 {
 	const char *data;
 	int size;
 	PyObject *inlined_obj;
 
 	if (!PyArg_ParseTuple(args, "s#O", &data, &size, &inlined_obj))
 		return -1;
 
 	return index_real_init(self, data, size, inlined_obj,
 			       PyTuple_GET_ITEM(args, 0));
 }
 
 static void index_dealloc(indexObject *self)
 {
+	_index_clearcaches(self);
 	Py_DECREF(self->data);
-	if (self->cache) {
-		Py_ssize_t i;
-
-		for (i = 0; i < self->raw_length; i++)
-			Py_XDECREF(self->cache[i]);
-	}
 	Py_XDECREF(self->added);
-	free(self->offsets);
 	PyObject_Del(self);
 }
 
 static PySequenceMethods index_sequence_methods = {
 	(lenfunc)index_length,   /* sq_length */
 	0,                       /* sq_concat */
 	0,                       /* sq_repeat */
 	(ssizeargfunc)index_get, /* sq_item */
 };
 
 static PyMappingMethods index_mapping_methods = {
 	(lenfunc)index_length,                 /* mp_length */
 	NULL,                                  /* mp_subscript */
 	(objobjargproc)index_assign_subscript, /* mp_ass_subscript */
 };
 
 static PyMethodDef index_methods[] = {
+	{"clearcaches", (PyCFunction)index_clearcaches, METH_NOARGS,
+	 "clear the index caches"},
 	{"insert", (PyCFunction)index_insert, METH_VARARGS,
 	 "insert an index entry"},
 	{NULL} /* Sentinel */
 };
 
 static PyTypeObject indexType = {
 	PyObject_HEAD_INIT(NULL)
 	0,                         /* ob_size */
 	"parsers.index",           /* tp_name */
 	sizeof(indexObject),       /* tp_basicsize */
 	0,                         /* tp_itemsize */
 	(destructor)index_dealloc, /* tp_dealloc */
 	0,                         /* tp_print */
 	0,                         /* tp_getattr */
 	0,                         /* tp_setattr */
 	0,                         /* tp_compare */
 	0,                         /* tp_repr */
 	0,                         /* tp_as_number */
 	&index_sequence_methods,   /* tp_as_sequence */
 	&index_mapping_methods,    /* tp_as_mapping */
 	0,                         /* tp_hash */
 	0,                         /* tp_call */
 	0,                         /* tp_str */
 	0,                         /* tp_getattro */
 	0,                         /* tp_setattro */
 	0,                         /* tp_as_buffer */
 	Py_TPFLAGS_DEFAULT,        /* tp_flags */
 	"revlog index",            /* tp_doc */
 	0,                         /* tp_traverse */
 	0,                         /* tp_clear */
 	0,                         /* tp_richcompare */
 	0,                         /* tp_weaklistoffset */
 	0,                         /* tp_iter */
 	0,                         /* tp_iternext */
 	index_methods,             /* tp_methods */
 	0,                         /* tp_members */
 	0,                         /* tp_getset */
 	0,                         /* tp_base */
 	0,                         /* tp_dict */
 	0,                         /* tp_descr_get */
 	0,                         /* tp_descr_set */
 	0,                         /* tp_dictoffset */
 	(initproc)index_init,      /* tp_init */
 	0,                         /* tp_alloc */
 	PyType_GenericNew,         /* tp_new */
 };
 
 /*
  * returns a tuple of the form (index, None, cache) with elements as
  * follows:
  *
  * index: an index object that lazily parses the RevlogNG records
  * cache: if data is inlined, a tuple (index_file_content, 0), else None
  *
  * added complications are for backwards compatibility
  */
 static PyObject *parse_index2(PyObject *self, PyObject *args)
 {
 	const char *data;
 	int size, ret;
 	PyObject *inlined_obj, *tuple = NULL, *cache = NULL;
 	indexObject *idx;
 
 	if (!PyArg_ParseTuple(args, "s#O", &data, &size, &inlined_obj))
 		return NULL;
 
 	idx = PyObject_New(indexObject, &indexType);
 
 	if (idx == NULL)
 		goto bail;
 
 	ret = index_real_init(idx, data, size, inlined_obj,
 			      PyTuple_GET_ITEM(args, 0));
 	if (ret)
 		goto bail;
 
 	if (idx->inlined) {
 		Py_INCREF(idx->data);
 		cache = Py_BuildValue("iO", 0, idx->data);
 		if (cache == NULL)
 			goto bail;
 	} else {
 		cache = Py_None;
 		Py_INCREF(cache);
 	}
 
 	tuple = Py_BuildValue("NN", idx, cache);
 	if (!tuple)
 		goto bail;
 	return tuple;
 
 bail:
 	Py_XDECREF(idx);
 	Py_XDECREF(cache);
 	Py_XDECREF(tuple);
 	return NULL;
 }
 
 static char parsers_doc[] = "Efficient content parsing.";
 
 static PyMethodDef methods[] = {
 	{"parse_manifest", parse_manifest, METH_VARARGS, "parse a manifest\n"},
 	{"parse_dirstate", parse_dirstate, METH_VARARGS, "parse a dirstate\n"},
 	{"parse_index2", parse_index2, METH_VARARGS, "parse a revlog index\n"},
 	{NULL, NULL}
 };
 
 static void module_init(PyObject *mod)
 {
 	static const char nullid[20];
 
 	if (PyType_Ready(&indexType) < 0)
 		return;
 	Py_INCREF(&indexType);
 
 	PyModule_AddObject(mod, "index", (PyObject *)&indexType);
 
 	nullentry = Py_BuildValue("iiiiiiis#", 0, 0, 0,
 				  -1, -1, -1, -1, nullid, 20);
 	if (nullentry)
 		PyObject_GC_UnTrack(nullentry);
 }
 
 #ifdef IS_PY3K
 static struct PyModuleDef parsers_module = {
 	PyModuleDef_HEAD_INIT,
 	"parsers",
 	parsers_doc,
 	-1,
 	methods
 };
 
 PyMODINIT_FUNC PyInit_parsers(void)
 {
 	PyObject *mod = PyModule_Create(&parsers_module);
 	module_init(mod);
 	return mod;
 }
 #else
 PyMODINIT_FUNC initparsers(void)
 {
 	PyObject *mod = Py_InitModule3("parsers", methods, parsers_doc);
 	module_init(mod);
 }
 #endif