view rust/hg-cpython/src/revlog.rs @ 43966:b69d5f3a41d0

rust-index: add a struct wrapping the C index

Implementing the full index logic in one go is journey larger than we would
like.

To achieve a smoother transition, we start with a simple Rust wrapper that delegates
allwork to the current C implementation. Once we will have a fully working index
object in Rust, we can easily start using more and more Rust Code with it.

The object in this patch is functional and tested. However, multiple of the
currently existing rust (in the `hg-cpython` crate) requires a `Graph`. Right
now we build this `Graph` (as cindex::Index) using the C index passed as
a PyObject. They will have to be updated to be made compatible.

Differential Revision: https://phab.mercurial-scm.org/D7655

// 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, 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> {
    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)?))
    }


    // 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)
    }
}

/// 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)
}