branchcache: add a "pure topological head" fast path
In a narrow but actually quick common case, all topological heads are all on
the same branch and all open. In this case, computing the branch map is very
simple. We can quickly detect situation where this situation will not change.
So we update the V3 format to be able to express this situation and upgrade the
update code to detect we remains in that mode.
The branch cache is populated with the actual value when the branch map is
accessed, but the update_disk method can do the update without needing to
populate it.
#include <Python.h>
#include <assert.h>
#include <stdlib.h>
#include <unistd.h>
#include <string>
#include "pyutil.h"
extern "C" {
static PYCODETYPE *code;
extern "C" int LLVMFuzzerInitialize(int *argc, char ***argv)
{
contrib::initpy(*argv[0]);
code = (PYCODETYPE *)Py_CompileString(R"py(
def maybeint(s, default):
try:
return int(s)
except ValueError:
return default
try:
parts = data.split('\0', 2)
if len(parts) == 3:
offset, stop, data = parts
elif len(parts) == 2:
stop, data = parts
offset = 0
else:
offset = stop = 0
offset, stop = maybeint(offset, 0), maybeint(stop, len(data))
parsers.fm1readmarkers(data, offset, stop)
except Exception as e:
pass
# uncomment this print if you're editing this Python code
# to debug failures.
# print e
)py",
"fuzzer", Py_file_input);
return 0;
}
int LLVMFuzzerTestOneInput(const uint8_t *Data, size_t Size)
{
PyObject *text =
PyBytes_FromStringAndSize((const char *)Data, (Py_ssize_t)Size);
PyObject *locals = PyDict_New();
PyDict_SetItemString(locals, "data", text);
PyObject *res = PyEval_EvalCode(code, contrib::pyglobals(), locals);
if (!res) {
PyErr_Print();
}
Py_XDECREF(res);
Py_DECREF(locals);
Py_DECREF(text);
return 0; // Non-zero return values are reserved for future use.
}
}