annotate rust/hg-cpython/src/revlog.rs @ 51199:44fbb7dfb563

rust-index: renamed nodemap error function for rev not in index

The function name was misleading, as the error wording mentions the
nodemap, hence would not be appropriate for missing revisions not
related to a nodemap lookup.

// 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},
    PyRevision,
};
use cpython::{
    buffer::{Element, PyBuffer},
    exc::{IndexError, ValueError},
    ObjectProtocol, PyBytes, PyClone, PyDict, PyErr, PyInt, PyModule,
    PyObject, PyResult, PyString, PyTuple, Python, PythonObject, ToPyObject,
};
use hg::{
    index::IndexHeader,
    index::{RevisionDataParams, COMPRESSION_MODE_INLINE},
    nodemap::{Block, NodeMapError, NodeTree},
    revlog::{nodemap::NodeMap, NodePrefix, RevlogIndex},
    BaseRevision, Revision, UncheckedRevision,
};
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 index: RefCell<hg::index::Index>;
    data nt: RefCell<Option<NodeTree>>;
    data docket: RefCell<Option<PyObject>>;
    // Holds a reference to the mmap'ed persistent nodemap data
    data nodemap_mmap: RefCell<Option<PyBuffer>>;
    // Holds a reference to the mmap'ed persistent index data
    data index_mmap: RefCell<Option<PyBuffer>>;

    def __new__(
        _cls,
        cindex: PyObject,
        data: PyObject,
        default_header: u32,
    ) -> PyResult<MixedIndex> {
        Self::new(py, cindex, data, default_header)
    }

    /// 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<PyRevision>> {
        let opt = self.get_nodetree(py)?.borrow();
        let nt = opt.as_ref().unwrap();
        let idx = &*self.cindex(py).borrow();
        let ridx = &*self.index(py).borrow();
        let node = node_from_py_bytes(py, &node)?;
        let rust_rev =
            nt.find_bin(ridx, node.into()).map_err(|e| nodemap_error(py, e))?;
        let c_rev =
            nt.find_bin(idx, node.into()).map_err(|e| nodemap_error(py, e))?;
        assert_eq!(rust_rev, c_rev);
        Ok(rust_rev.map(Into::into))

    }

    /// 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<PyRevision> {
        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, format!("Invalid node or prefix '{}'", node_as_string))
            )?;

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

        // This is ok since we will just add the revision to the index
        let rev = Revision(rev);
        idx.append(py, tup.clone_ref(py))?;
        self.index(py)
            .borrow_mut()
            .append(py_tuple_to_revision_data_params(py, tup)?)
            .unwrap();
        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 start = key.getattr(py, "start")?;
        let start = UncheckedRevision(start.extract(py)?);
        let start = self.index(py)
            .borrow()
            .check_revision(start)
            .ok_or_else(|| {
                nodemap_error(py, NodeMapError::RevisionNotInIndex(start))
            })?;
        self.index(py).borrow_mut().remove(start).unwrap();
        let mut opt = self.get_nodetree(py)?.borrow_mut();
        let nt = opt.as_mut().unwrap();
        nt.invalidate_all();
        self.fill_nodemap(py, 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.nodemap_mmap(py).borrow_mut().take();
        self.index(py).borrow_mut().clear_caches();
        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> {
        let rindex = self.index(py).borrow();
        let packed = rindex.pack_header(args.get_item(py, 0).extract(py)?);
        let packed = PyBytes::new(py, &packed);
        let cpacked = self.call_cindex(py, "pack_header", args, kw)?;
        assert!(packed.as_object().compare(py, cpacked)?.is_eq());
        Ok(packed.into_object())
    }

    /// 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.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::<i32>(py) {
            Ok(rev) => rev.to_py_object(py).into_object(),
            Err(_) => key,
        };
        self.cindex(py).borrow().inner().get_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::<i32>(py) {
            Ok(rev) => {
                Ok(rev >= -1 && rev < self.len(py)? as BaseRevision)
            }
            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)
    }

});

/// Take a (potentially) mmap'ed buffer, and return the underlying Python
/// buffer along with the Rust slice into said buffer. We need to keep the
/// Python buffer around, otherwise we'd get a dangling pointer once the buffer
/// is freed from Python's side.
///
/// # Safety
///
/// The caller must make sure that the buffer is kept around for at least as
/// long as the slice.
#[deny(unsafe_op_in_unsafe_fn)]
unsafe fn mmap_keeparound(
    py: Python,
    data: PyObject,
) -> PyResult<(
    PyBuffer,
    Box<dyn std::ops::Deref<Target = [u8]> + Send + 'static>,
)> {
    let buf = PyBuffer::get(py, &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(),
        ));
    };

    Ok((buf, Box::new(bytes)))
}

fn py_tuple_to_revision_data_params(
    py: Python,
    tuple: PyTuple,
) -> PyResult<RevisionDataParams> {
    if tuple.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 offset_or_flags: u64 = tuple.get_item(py, 0).extract(py)?;
    let node_id = tuple
        .get_item(py, 7)
        .extract::<PyBytes>(py)?
        .data(py)
        .try_into()
        .unwrap();
    let flags = (offset_or_flags & 0xFFFF) as u16;
    let data_offset = offset_or_flags >> 16;
    Ok(RevisionDataParams {
        flags,
        data_offset,
        data_compressed_length: tuple.get_item(py, 1).extract(py)?,
        data_uncompressed_length: tuple.get_item(py, 2).extract(py)?,
        data_delta_base: tuple.get_item(py, 3).extract(py)?,
        link_rev: tuple.get_item(py, 4).extract(py)?,
        parent_rev_1: tuple.get_item(py, 5).extract(py)?,
        parent_rev_2: tuple.get_item(py, 6).extract(py)?,
        node_id,
        _sidedata_offset: 0,
        _sidedata_compressed_length: 0,
        data_compression_mode: COMPRESSION_MODE_INLINE,
        _sidedata_compression_mode: COMPRESSION_MODE_INLINE,
        _rank: -1,
    })
}

impl MixedIndex {
    fn new(
        py: Python,
        cindex: PyObject,
        data: PyObject,
        header: u32,
    ) -> PyResult<MixedIndex> {
        // Safety: we keep the buffer around inside the class as `index_mmap`
        let (buf, bytes) = unsafe { mmap_keeparound(py, data)? };

        Self::create_instance(
            py,
            RefCell::new(cindex::Index::new(py, cindex)?),
            RefCell::new(
                hg::index::Index::new(
                    bytes,
                    IndexHeader::parse(&header.to_be_bytes())
                        .expect("default header is broken")
                        .unwrap(),
                )
                .unwrap(),
            ),
            RefCell::new(None),
            RefCell::new(None),
            RefCell::new(None),
            RefCell::new(Some(buf)),
        )
    }

    fn len(&self, py: Python) -> PyResult<usize> {
        let rust_index_len = self.index(py).borrow().len();
        let cindex_len = self.cindex(py).borrow().inner().len(py)?;
        assert_eq!(rust_index_len, cindex_len);
        Ok(cindex_len)
    }

    /// 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..self.len(py)? {
            let rev = Revision(r as BaseRevision);
            // 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::<Vec<_>>::default();
            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::<Vec<_>>::default(), 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> {
        // Safety: we keep the buffer around inside the class as `nodemap_mmap`
        let (buf, bytes) = unsafe { mmap_keeparound(py, nm_data)? };
        let len = buf.item_count();
        self.nodemap_mmap(py).borrow_mut().replace(buf);

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

        let data_tip = docket
            .getattr(py, "tip_rev")?
            .extract::<BaseRevision>(py)?
            .into();
        self.docket(py).borrow_mut().replace(docket.clone_ref(py));
        let idx = self.cindex(py).borrow();
        let data_tip = idx.check_revision(data_tip).ok_or_else(|| {
            nodemap_error(py, NodeMapError::RevisionNotInIndex(data_tip))
        })?;
        let current_tip = idx.len();

        for r in (data_tip.0 + 1)..current_tip as BaseRevision {
            let rev = Revision(r);
            // 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 nodemap_rev_not_in_index(py: Python, rev: UncheckedRevision) -> 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) => nodemap_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)
}