comparison rust/hg-cpython/src/cindex.rs @ 43959:f384d68d8ea8

revlog: made C Capsule an array of function pointers

Although it's perfectly valid to put a function pointer in
a capsule, as we've been doing since the start of rust/hg-cpython,
an array of function pointers has several advantages:

- it can hold several functions. That's our main motivation here.
  We plan to expose index_length() and index_node(), which will
  be needed for a Rust implementation of nodemap.
- it could also have data
- (probably minor in the case of Mercurial) proper support for
  architectures for which data and code pointers don't have the
  same size.

Differential Revision: https://phab.mercurial-scm.org/D7543

43958:26cf356ae772

use cpython::{PyClone, PyObject, PyResult, Python};
use hg::{Graph, GraphError, Revision, WORKING_DIRECTORY_REVISION};
use libc::c_int;

py_capsule_fn!(
    from mercurial.cext.parsers import index_get_parents_CAPI
        as get_parents_capi
        signature (
            index: *mut RawPyObject,
            rev: c_int,
            ps: *mut [c_int; 2],
        ) -> c_int
);

/// A `Graph` backed up by objects and functions from revlog.c
///
/// This implementation of the `Graph` trait, relies on (pointers to)
/// - the C index object (`index` member)

/// the core API, that would be tied to `GILGuard` / `Python<'p>`
/// in the case of the `cpython` crate bindings yet could leave room for other
/// mechanisms in other contexts.
pub struct Index {
    index: PyObject,
    parents: get_parents_capi::CapsuleFn,
}

impl Index {
    pub fn new(py: Python, index: PyObject) -> PyResult<Self> {
        Ok(Index {
            index: index,
            parents: get_parents_capi::retrieve(py)?,
        })
    }
}

impl Clone for Index {
    fn clone(&self) -> Self {
        let guard = Python::acquire_gil();
        Index {
            index: self.index.clone_ref(guard.python()),
            parents: self.parents.clone(),
        }
    }
}

impl Graph for Index {

        if rev == WORKING_DIRECTORY_REVISION {
            return Err(GraphError::WorkingDirectoryUnsupported);
        }
        let mut res: [c_int; 2] = [0; 2];
        let code = unsafe {
            (self.parents)(
                self.index.as_ptr(),
                rev as c_int,
                &mut res as *mut [c_int; 2],
            )
        };

43959:f384d68d8ea8

use cpython::{PyClone, PyObject, PyResult, Python};
use hg::{Graph, GraphError, Revision, WORKING_DIRECTORY_REVISION};
use libc::c_int;

#[repr(C)]
pub struct Revlog_CAPI {
    index_parents: unsafe extern "C" fn(
        index: *mut revlog_capi::RawPyObject,
        rev: c_int,
        ps: *mut [c_int; 2],
    ) -> c_int,
}

py_capsule!(
    from mercurial.cext.parsers import revlog_CAPI
        as revlog_capi for Revlog_CAPI);

/// A `Graph` backed up by objects and functions from revlog.c
///
/// This implementation of the `Graph` trait, relies on (pointers to)
/// - the C index object (`index` member)

/// the core API, that would be tied to `GILGuard` / `Python<'p>`
/// in the case of the `cpython` crate bindings yet could leave room for other
/// mechanisms in other contexts.
pub struct Index {
    index: PyObject,
    capi: &'static Revlog_CAPI,
}

impl Index {
    pub fn new(py: Python, index: PyObject) -> PyResult<Self> {
        Ok(Index {
            index: index,
            capi: unsafe { revlog_capi::retrieve(py)? },
        })
    }
}

impl Clone for Index {
    fn clone(&self) -> Self {
        let guard = Python::acquire_gil();
        Index {
            index: self.index.clone_ref(guard.python()),
            capi: self.capi,
        }
    }
}

impl Graph for Index {

        if rev == WORKING_DIRECTORY_REVISION {
            return Err(GraphError::WorkingDirectoryUnsupported);
        }
        let mut res: [c_int; 2] = [0; 2];
        let code = unsafe {
            (self.capi.index_parents)(
                self.index.as_ptr(),
                rev as c_int,
                &mut res as *mut [c_int; 2],
            )
        };