sparse-revlog: add a `index_get_length` function in C
We are about to implement a native version of `slicechunktodensity`. For
clarity, we introduce the helper functions first. This new function provides
an efficient way to retrieve some of the information needed by
`slicechunktodensity`.
--- a/mercurial/cext/revlog.c Tue Nov 20 14:49:18 2018 +0000
+++ b/mercurial/cext/revlog.c Fri Nov 09 18:42:58 2018 +0100
@@ -10,6 +10,7 @@
#include <Python.h>
#include <assert.h>
#include <ctype.h>
+#include <limits.h>
#include <stddef.h>
#include <string.h>
@@ -219,6 +220,31 @@
return (int64_t)(offset >> 16);
}
+static inline int index_get_length(indexObject *self, Py_ssize_t rev)
+{
+ if (rev >= self->length) {
+ PyObject *tuple;
+ PyObject *pylong;
+ long ret;
+ tuple = PyList_GET_ITEM(self->added, rev - self->length);
+ pylong = PyTuple_GET_ITEM(tuple, 1);
+ ret = PyInt_AsLong(pylong);
+ if (ret == -1 && PyErr_Occurred()) {
+ return -1;
+ }
+ if (ret < 0 || ret > (long)INT_MAX) {
+ PyErr_Format(PyExc_OverflowError,
+ "revlog entry size out of bound (%ld)",
+ ret);
+ return -1;
+ }
+ return (int)ret;
+ } else {
+ const char *data = index_deref(self, rev);
+ return (int)getbe32(data + 8);
+ }
+}
+
/*
* RevlogNG format (all in big endian, data may be inlined):
* 6 bytes: offset