rust/hg-cpython/src/revlog.rs

dirstate-map: move most of `dirstate.update_file` logic in the dsmap

A new `reset_state` method is introduced to deal with most of that logic. This
move things one layer lower, but the ultimate goal is to deal with most of this
at the DirstateItem level.

This reveal various imperfection with the data passed to update_file by
`mergestate.recordupdates`, however this is orthogonal to this patch and should
be dealt with at a higher level.

Differential Revision: https://phab.mercurial-scm.org/D11134

// revlog.rs
//
// Copyright 2019-2020 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,
    utils::{node_from_py_bytes, node_from_py_object},
};
use cpython::{
    buffer::{Element, PyBuffer},
    exc::{IndexError, ValueError},
    ObjectProtocol, PyBytes, PyClone, PyDict, PyErr, PyInt, PyModule,
    PyObject, PyResult, PyString, PyTuple, Python, PythonObject, ToPyObject,
};
use hg::{
    nodemap::{Block, NodeMapError, NodeTree},
    revlog::{nodemap::NodeMap, NodePrefix, RevlogIndex},
    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>;
    data nt: RefCell<Option<NodeTree>>;
    data docket: RefCell<Option<PyObject>>;
    // Holds a reference to the mmap'ed persistent nodemap data
    data mmap: RefCell<Option<PyBuffer>>;

    def __new__(_cls, cindex: PyObject) -> PyResult<MixedIndex> {
        Self::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))
    }

    // Index API involving nodemap, as defined in mercurial/pure/parsers.py

    /// Return Revision if found, raises a bare `error.RevlogError`
    /// in case of ambiguity, same as C version does
    def get_rev(&self, node: PyBytes) -> PyResult<Option<Revision>> {
        let opt = self.get_nodetree(py)?.borrow();
        let nt = opt.as_ref().unwrap();
        let idx = &*self.cindex(py).borrow();
        let node = node_from_py_bytes(py, &node)?;
        nt.find_bin(idx, node.into()).map_err(|e| nodemap_error(py, e))
    }

    /// same as `get_rev()` but raises a bare `error.RevlogError` if node
    /// is not found.
    ///
    /// No need to repeat `node` in the exception, `mercurial/revlog.py`
    /// will catch and rewrap with it
    def rev(&self, node: PyBytes) -> PyResult<Revision> {
        self.get_rev(py, node)?.ok_or_else(|| revlog_error(py))
    }

    /// return True if the node exist in the index
    def has_node(&self, node: PyBytes) -> PyResult<bool> {
        self.get_rev(py, node).map(|opt| opt.is_some())
    }

    /// find length of shortest hex nodeid of a binary ID
    def shortest(&self, node: PyBytes) -> PyResult<usize> {
        let opt = self.get_nodetree(py)?.borrow();
        let nt = opt.as_ref().unwrap();
        let idx = &*self.cindex(py).borrow();
        match nt.unique_prefix_len_node(idx, &node_from_py_bytes(py, &node)?)
        {
            Ok(Some(l)) => Ok(l),
            Ok(None) => Err(revlog_error(py)),
            Err(e) => Err(nodemap_error(py, e)),
        }
    }

    def partialmatch(&self, node: PyObject) -> PyResult<Option<PyBytes>> {
        let opt = self.get_nodetree(py)?.borrow();
        let nt = opt.as_ref().unwrap();
        let idx = &*self.cindex(py).borrow();

        let node_as_string = if cfg!(feature = "python3-sys") {
            node.cast_as::<PyString>(py)?.to_string(py)?.to_string()
        }
        else {
            let node = node.extract::<PyBytes>(py)?;
            String::from_utf8_lossy(node.data(py)).to_string()
        };

        let prefix = NodePrefix::from_hex(&node_as_string).map_err(|_| PyErr::new::<ValueError, _>(py, "Invalid node or prefix"))?;

        nt.find_bin(idx, prefix)
            // TODO make an inner API returning the node directly
            .map(|opt| opt.map(
                |rev| PyBytes::new(py, idx.node(rev).unwrap().as_bytes())))
            .map_err(|e| nodemap_error(py, e))

    }

    /// append an index entry
    def append(&self, tup: PyTuple) -> PyResult<PyObject> {
        if tup.len(py) < 8 {
            // this is better than the panic promised by tup.get_item()
            return Err(
                PyErr::new::<IndexError, _>(py, "tuple index out of range"))
        }
        let node_bytes = tup.get_item(py, 7).extract(py)?;
        let node = node_from_py_object(py, &node_bytes)?;

        let mut idx = self.cindex(py).borrow_mut();
        let rev = idx.len() as Revision;

        idx.append(py, tup)?;
        self.get_nodetree(py)?.borrow_mut().as_mut().unwrap()
            .insert(&*idx, &node, rev)
            .map_err(|e| nodemap_error(py, e))?;
        Ok(py.None())
    }

    def __delitem__(&self, key: PyObject) -> PyResult<()> {
        // __delitem__ is both for `del idx[r]` and `del idx[r1:r2]`
        self.cindex(py).borrow().inner().del_item(py, key)?;
        let mut opt = self.get_nodetree(py)?.borrow_mut();
        let mut nt = opt.as_mut().unwrap();
        nt.invalidate_all();
        self.fill_nodemap(py, &mut nt)?;
        Ok(())
    }

    //
    // 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 and inner py_class data.
    /// It is Python's responsibility to call `update_nodemap_data` again.
    def clearcaches(&self, *args, **kw) -> PyResult<PyObject> {
        self.nt(py).borrow_mut().take();
        self.docket(py).borrow_mut().take();
        self.mmap(py).borrow_mut().take();
        self.call_cindex(py, "clearcaches", args, kw)
    }

    /// return the raw binary string representing a revision
    def entry_binary(&self, *args, **kw) -> PyResult<PyObject> {
        self.call_cindex(py, "entry_binary", args, kw)
    }

    /// return a binary packed version of the header
    def pack_header(&self, *args, **kw) -> PyResult<PyObject> {
        self.call_cindex(py, "pack_header", args, kw)
    }

    /// get an index entry
    def get(&self, *args, **kw) -> PyResult<PyObject> {
        self.call_cindex(py, "get", 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)
    }

    /// 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 possibly be better
        // 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 __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)
            }
        }
    }

    def nodemap_data_all(&self) -> PyResult<PyBytes> {
        self.inner_nodemap_data_all(py)
    }

    def nodemap_data_incremental(&self) -> PyResult<PyObject> {
        self.inner_nodemap_data_incremental(py)
    }
    def update_nodemap_data(
        &self,
        docket: PyObject,
        nm_data: PyObject
    ) -> PyResult<PyObject> {
        self.inner_update_nodemap_data(py, docket, nm_data)
    }

    @property
    def entry_size(&self) -> PyResult<PyInt> {
        self.cindex(py).borrow().inner().getattr(py, "entry_size")?.extract::<PyInt>(py)
    }

    @property
    def rust_ext_compat(&self) -> PyResult<PyInt> {
        self.cindex(py).borrow().inner().getattr(py, "rust_ext_compat")?.extract::<PyInt>(py)
    }

});

impl MixedIndex {
    fn new(py: Python, cindex: PyObject) -> PyResult<MixedIndex> {
        Self::create_instance(
            py,
            RefCell::new(cindex::Index::new(py, cindex)?),
            RefCell::new(None),
            RefCell::new(None),
            RefCell::new(None),
        )
    }

    /// This is scaffolding at this point, but it could also become
    /// a way to start a persistent nodemap or perform a
    /// vacuum / repack operation
    fn fill_nodemap(
        &self,
        py: Python,
        nt: &mut NodeTree,
    ) -> PyResult<PyObject> {
        let index = self.cindex(py).borrow();
        for r in 0..index.len() {
            let rev = r as Revision;
            // in this case node() won't ever return None
            nt.insert(&*index, index.node(rev).unwrap(), rev)
                .map_err(|e| nodemap_error(py, e))?
        }
        Ok(py.None())
    }

    fn get_nodetree<'a>(
        &'a self,
        py: Python<'a>,
    ) -> PyResult<&'a RefCell<Option<NodeTree>>> {
        if self.nt(py).borrow().is_none() {
            let readonly = Box::new(Vec::new());
            let mut nt = NodeTree::load_bytes(readonly, 0);
            self.fill_nodemap(py, &mut nt)?;
            self.nt(py).borrow_mut().replace(nt);
        }
        Ok(self.nt(py))
    }

    /// 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)
    }

    /// Returns the full nodemap bytes to be written as-is to disk
    fn inner_nodemap_data_all(&self, py: Python) -> PyResult<PyBytes> {
        let nodemap = self.get_nodetree(py)?.borrow_mut().take().unwrap();
        let (readonly, bytes) = nodemap.into_readonly_and_added_bytes();

        // If there's anything readonly, we need to build the data again from
        // scratch
        let bytes = if readonly.len() > 0 {
            let mut nt = NodeTree::load_bytes(Box::new(vec![]), 0);
            self.fill_nodemap(py, &mut nt)?;

            let (readonly, bytes) = nt.into_readonly_and_added_bytes();
            assert_eq!(readonly.len(), 0);

            bytes
        } else {
            bytes
        };

        let bytes = PyBytes::new(py, &bytes);
        Ok(bytes)
    }

    /// Returns the last saved docket along with the size of any changed data
    /// (in number of blocks), and said data as bytes.
    fn inner_nodemap_data_incremental(
        &self,
        py: Python,
    ) -> PyResult<PyObject> {
        let docket = self.docket(py).borrow();
        let docket = match docket.as_ref() {
            Some(d) => d,
            None => return Ok(py.None()),
        };

        let node_tree = self.get_nodetree(py)?.borrow_mut().take().unwrap();
        let masked_blocks = node_tree.masked_readonly_blocks();
        let (_, data) = node_tree.into_readonly_and_added_bytes();
        let changed = masked_blocks * std::mem::size_of::<Block>();

        Ok((docket, changed, PyBytes::new(py, &data))
            .to_py_object(py)
            .into_object())
    }

    /// Update the nodemap from the new (mmaped) data.
    /// The docket is kept as a reference for later incremental calls.
    fn inner_update_nodemap_data(
        &self,
        py: Python,
        docket: PyObject,
        nm_data: PyObject,
    ) -> PyResult<PyObject> {
        let buf = PyBuffer::get(py, &nm_data)?;
        let len = buf.item_count();

        // Build a slice from the mmap'ed buffer data
        let cbuf = buf.buf_ptr();
        let bytes = if std::mem::size_of::<u8>() == buf.item_size()
            && buf.is_c_contiguous()
            && u8::is_compatible_format(buf.format())
        {
            unsafe { std::slice::from_raw_parts(cbuf as *const u8, len) }
        } else {
            return Err(PyErr::new::<ValueError, _>(
                py,
                "Nodemap data buffer has an invalid memory representation"
                    .to_string(),
            ));
        };

        // Keep a reference to the mmap'ed buffer, otherwise we get a dangling
        // pointer.
        self.mmap(py).borrow_mut().replace(buf);

        let mut nt = NodeTree::load_bytes(Box::new(bytes), len);

        let data_tip =
            docket.getattr(py, "tip_rev")?.extract::<Revision>(py)?;
        self.docket(py).borrow_mut().replace(docket.clone_ref(py));
        let idx = self.cindex(py).borrow();
        let current_tip = idx.len();

        for r in (data_tip + 1)..current_tip as Revision {
            let rev = r as Revision;
            // in this case node() won't ever return None
            nt.insert(&*idx, idx.node(rev).unwrap(), rev)
                .map_err(|e| nodemap_error(py, e))?
        }

        *self.nt(py).borrow_mut() = Some(nt);

        Ok(py.None())
    }
}

fn revlog_error(py: Python) -> PyErr {
    match py
        .import("mercurial.error")
        .and_then(|m| m.get(py, "RevlogError"))
    {
        Err(e) => e,
        Ok(cls) => PyErr::from_instance(
            py,
            cls.call(py, (py.None(),), None).ok().into_py_object(py),
        ),
    }
}

fn rev_not_in_index(py: Python, rev: Revision) -> PyErr {
    PyErr::new::<ValueError, _>(
        py,
        format!(
            "Inconsistency: Revision {} found in nodemap \
             is not in revlog index",
            rev
        ),
    )
}

/// Standard treatment of NodeMapError
fn nodemap_error(py: Python, err: NodeMapError) -> PyErr {
    match err {
        NodeMapError::MultipleResults => revlog_error(py),
        NodeMapError::RevisionNotInIndex(r) => rev_not_in_index(py, r),
    }
}

/// 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)
}