rust-index: expose a method to retrieve the C index

The code for `shortesthexnodeidprefix` need to access the actual C index. For
now we grant its wish and expose a method to do so. Once we have the nodemap in
Rust, we will be able to implement the same feature from rust and we will be
able to drop this method.

Differential Revision: https://phab.mercurial-scm.org/D7658

rust/hg-cpython/src/revlog.rs

@@ -1,221 +1,232 b''
 // revlog.rs
 //
 // Copyright 2019 Georges Racinet <[e-mail]>
 //
 // This software may be used and distributed according to the terms of the
 // GNU General Public License version 2 or any later version.
 
 use crate::cindex;
 use cpython::{
     ObjectProtocol, PyClone, PyDict, PyModule, PyObject, PyResult, PyTuple, Python, PythonObject,
     ToPyObject,
 };
 use hg::Revision;
 use std::cell::RefCell;
 
 /// Return a Struct implementing the Graph trait
 pub(crate) fn pyindex_to_graph(py: Python, index: PyObject) -> PyResult<cindex::Index> {
     match index.extract::<MixedIndex>(py) {
         Ok(midx) => Ok(midx.clone_cindex(py)),
         Err(_) => cindex::Index::new(py, index),
     }
 }
 
 py_class!(pub class MixedIndex |py| {
     data cindex: RefCell<cindex::Index>;
 
     def __new__(_cls, cindex: PyObject) -> PyResult<MixedIndex> {
         Self::create_instance(py, RefCell::new(
             cindex::Index::new(py, cindex)?))
     }
 
+    /// Compatibility layer used for Python consumers needing access to the C index
+    ///
+    /// Only use case so far is `scmutil.shortesthexnodeidprefix`,
+    /// that may need to build a custom `nodetree`, based on a specified revset.
+    /// With a Rust implementation of the nodemap, we will be able to get rid of
+    /// this, by exposing our own standalone nodemap class,
+    /// ready to accept `MixedIndex`.
+    def get_cindex(&self) -> PyResult<PyObject> {
+        Ok(self.cindex(py).borrow().inner().clone_ref(py))
+    }
+
 
     // Reforwarded C index API
 
     // index_methods (tp_methods). Same ordering as in revlog.c
 
     /// return the gca set of the given revs
     def ancestors(&self, *args, **kw) -> PyResult<PyObject> {
         self.call_cindex(py, "ancestors", args, kw)
     }
 
     /// return the heads of the common ancestors of the given revs
     def commonancestorsheads(&self, *args, **kw) -> PyResult<PyObject> {
         self.call_cindex(py, "commonancestorsheads", args, kw)
     }
 
     /// clear the index caches
     def clearcaches(&self, *args, **kw) -> PyResult<PyObject> {
         self.call_cindex(py, "clearcaches", args, kw)
     }
 
     /// get an index entry
     def get(&self, *args, **kw) -> PyResult<PyObject> {
         self.call_cindex(py, "get", args, kw)
     }
 
     /// return `rev` associated with a node or None
     def get_rev(&self, *args, **kw) -> PyResult<PyObject> {
         self.call_cindex(py, "get_rev", args, kw)
     }
 
     /// return True if the node exist in the index
     def has_node(&self, *args, **kw) -> PyResult<PyObject> {
         self.call_cindex(py, "has_node", args, kw)
     }
 
     /// return `rev` associated with a node or raise RevlogError
     def rev(&self, *args, **kw) -> PyResult<PyObject> {
         self.call_cindex(py, "rev", args, kw)
     }
 
     /// compute phases
     def computephasesmapsets(&self, *args, **kw) -> PyResult<PyObject> {
         self.call_cindex(py, "computephasesmapsets", args, kw)
     }
 
     /// reachableroots
     def reachableroots2(&self, *args, **kw) -> PyResult<PyObject> {
         self.call_cindex(py, "reachableroots2", args, kw)
     }
 
     /// get head revisions
     def headrevs(&self, *args, **kw) -> PyResult<PyObject> {
         self.call_cindex(py, "headrevs", args, kw)
     }
 
     /// get filtered head revisions
     def headrevsfiltered(&self, *args, **kw) -> PyResult<PyObject> {
         self.call_cindex(py, "headrevsfiltered", args, kw)
     }
 
     /// True if the object is a snapshot
     def issnapshot(&self, *args, **kw) -> PyResult<PyObject> {
         self.call_cindex(py, "issnapshot", args, kw)
     }
 
     /// Gather snapshot data in a cache dict
     def findsnapshots(&self, *args, **kw) -> PyResult<PyObject> {
         self.call_cindex(py, "findsnapshots", args, kw)
     }
 
     /// determine revisions with deltas to reconstruct fulltext
     def deltachain(&self, *args, **kw) -> PyResult<PyObject> {
         self.call_cindex(py, "deltachain", args, kw)
     }
 
     /// slice planned chunk read to reach a density threshold
     def slicechunktodensity(&self, *args, **kw) -> PyResult<PyObject> {
         self.call_cindex(py, "slicechunktodensity", args, kw)
     }
 
     /// append an index entry
     def append(&self, *args, **kw) -> PyResult<PyObject> {
         self.call_cindex(py, "append", args, kw)
     }
 
     /// match a potentially ambiguous node ID
     def partialmatch(&self, *args, **kw) -> PyResult<PyObject> {
         self.call_cindex(py, "partialmatch", args, kw)
     }
 
     /// find length of shortest hex nodeid of a binary ID
     def shortest(&self, *args, **kw) -> PyResult<PyObject> {
         self.call_cindex(py, "shortest", args, kw)
     }
 
     /// stats for the index
     def stats(&self, *args, **kw) -> PyResult<PyObject> {
         self.call_cindex(py, "stats", args, kw)
     }
 
     // index_sequence_methods and index_mapping_methods.
     //
     // Since we call back through the high level Python API,
     // there's no point making a distinction between index_get
     // and index_getitem.
 
     def __len__(&self) -> PyResult<usize> {
         self.cindex(py).borrow().inner().len(py)
     }
 
     def __getitem__(&self, key: PyObject) -> PyResult<PyObject> {
         // this conversion seems needless, but that's actually because
         // `index_getitem` does not handle conversion from PyLong,
         // which expressions such as [e for e in index] internally use.
         // Note that we don't seem to have a direct way to call
         // PySequence_GetItem (does the job), which would be better for
         // for performance
         let key = match key.extract::<Revision>(py) {
             Ok(rev) => rev.to_py_object(py).into_object(),
             Err(_) => key,
         };
         self.cindex(py).borrow().inner().get_item(py, key)
     }
 
     def __setitem__(&self, key: PyObject, value: PyObject) -> PyResult<()> {
         self.cindex(py).borrow().inner().set_item(py, key, value)
     }
 
     def __delitem__(&self, key: PyObject) -> PyResult<()> {
         self.cindex(py).borrow().inner().del_item(py, key)
     }
 
     def __contains__(&self, item: PyObject) -> PyResult<bool> {
         // ObjectProtocol does not seem to provide contains(), so
         // this is an equivalent implementation of the index_contains()
         // defined in revlog.c
         let cindex = self.cindex(py).borrow();
         match item.extract::<Revision>(py) {
             Ok(rev) => {
                 Ok(rev >= -1 && rev < cindex.inner().len(py)? as Revision)
             }
             Err(_) => {
                 cindex.inner().call_method(
                     py,
                     "has_node",
                     PyTuple::new(py, &[item]),
                     None)?
                 .extract(py)
             }
         }
     }
 
 
 });
 
 impl MixedIndex {
     /// forward a method call to the underlying C index
     fn call_cindex(
         &self,
         py: Python,
         name: &str,
         args: &PyTuple,
         kwargs: Option<&PyDict>,
     ) -> PyResult<PyObject> {
         self.cindex(py)
             .borrow()
             .inner()
             .call_method(py, name, args, kwargs)
     }
 
     pub fn clone_cindex(&self, py: Python) -> cindex::Index {
         self.cindex(py).borrow().clone_ref(py)
     }
 }
 
 /// Create the module, with __package__ given from parent
 pub fn init_module(py: Python, package: &str) -> PyResult<PyModule> {
     let dotted_name = &format!("{}.revlog", package);
     let m = PyModule::new(py, dotted_name)?;
     m.add(py, "__package__", package)?;
     m.add(py, "__doc__", "RevLog - Rust implementations")?;
 
     m.add_class::<MixedIndex>(py)?;
 
     let sys = PyModule::import(py, "sys")?;
     let sys_modules: PyDict = sys.get(py, "modules")?.extract(py)?;
     sys_modules.set_item(py, dotted_name, &m)?;
 
     Ok(m)
 }

tests/test-rust-revlog.py

@@ -1,53 +1,60 b''
 from __future__ import absolute_import
 import unittest
 
 try:
     from mercurial import rustext
 
     rustext.__name__  # trigger immediate actual import
 except ImportError:
     rustext = None
 else:
     from mercurial.rustext import revlog
 
     # this would fail already without appropriate ancestor.__package__
     from mercurial.rustext.ancestor import LazyAncestors
 
 from mercurial.testing import revlog as revlogtesting
 
 
 @unittest.skipIf(
     rustext is None, "rustext module revlog relies on is not available",
 )
 class RustRevlogIndexTest(revlogtesting.RevlogBasedTestBase):
     def test_heads(self):
         idx = self.parseindex()
         rustidx = revlog.MixedIndex(idx)
         self.assertEqual(rustidx.headrevs(), idx.headrevs())
 
+    def test_get_cindex(self):
+        # drop me once we no longer need the method for shortest node
+        idx = self.parseindex()
+        rustidx = revlog.MixedIndex(idx)
+        cidx = rustidx.get_cindex()
+        self.assertTrue(idx is cidx)
+
     def test_len(self):
         idx = self.parseindex()
         rustidx = revlog.MixedIndex(idx)
         self.assertEqual(len(rustidx), len(idx))
 
     def test_ancestors(self):
         idx = self.parseindex()
         rustidx = revlog.MixedIndex(idx)
         lazy = LazyAncestors(rustidx, [3], 0, True)
         # we have two more references to the index:
         # - in its inner iterator for __contains__ and __bool__
         # - in the LazyAncestors instance itself (to spawn new iterators)
         self.assertTrue(2 in lazy)
         self.assertTrue(bool(lazy))
         self.assertEqual(list(lazy), [3, 2, 1, 0])
         # a second time to validate that we spawn new iterators
         self.assertEqual(list(lazy), [3, 2, 1, 0])
 
         # let's check bool for an empty one
         self.assertFalse(LazyAncestors(idx, [0], 0, False))
 
 
 if __name__ == '__main__':
     import silenttestrunner
 
     silenttestrunner.main(__name__)