cindex.rs
102 lines
| 3.3 KiB
| application/rls-services+xml
|
RustLexer
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r41082 | // cindex.rs | ||
// | ||||
// Copyright 2018 Georges Racinet <gracinet@anybox.fr> | ||||
// | ||||
// This software may be used and distributed according to the terms of the | ||||
// GNU General Public License version 2 or any later version. | ||||
//! Bindings to use the Index defined by the parsers C extension | ||||
//! | ||||
//! Ideally, we should use an Index entirely implemented in Rust, | ||||
//! but this will take some time to get there. | ||||
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r43484 | use cpython::{PyClone, PyObject, PyResult, Python}; | ||
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r41386 | use hg::{Graph, GraphError, Revision, WORKING_DIRECTORY_REVISION}; | ||
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r41082 | use libc::c_int; | ||
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r43484 | 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 | ||||
); | ||||
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r41082 | |||
/// 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 `index_get_parents()` function (`parents` member) | ||||
/// | ||||
/// # Safety | ||||
/// | ||||
/// The C index itself is mutable, and this Rust exposition is **not | ||||
/// protected by the GIL**, meaning that this construct isn't safe with respect | ||||
/// to Python threads. | ||||
/// | ||||
/// All callers of this `Index` must acquire the GIL and must not release it | ||||
/// while working. | ||||
/// | ||||
/// # TODO find a solution to make it GIL safe again. | ||||
/// | ||||
/// This is non trivial, and can wait until we have a clearer picture with | ||||
/// more Rust Mercurial constructs. | ||||
/// | ||||
/// One possibility would be to a `GILProtectedIndex` wrapper enclosing | ||||
/// a `Python<'p>` marker and have it be the one implementing the | ||||
/// `Graph` trait, but this would mean the `Graph` implementor would become | ||||
/// likely to change between subsequent method invocations of the `hg-core` | ||||
/// objects (a serious change of the `hg-core` API): | ||||
/// either exposing ways to mutate the `Graph`, or making it a non persistent | ||||
/// parameter in the relevant methods that need one. | ||||
/// | ||||
/// Another possibility would be to introduce an abstract lock handle into | ||||
/// 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, | ||||
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r43484 | parents: get_parents_capi::CapsuleFn, | ||
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r41082 | } | ||
impl Index { | ||||
pub fn new(py: Python, index: PyObject) -> PyResult<Self> { | ||||
Ok(Index { | ||||
index: index, | ||||
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r43484 | parents: get_parents_capi::retrieve(py)?, | ||
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r41082 | }) | ||
} | ||||
} | ||||
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r41084 | 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(), | ||||
} | ||||
} | ||||
} | ||||
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r41082 | impl Graph for Index { | ||
/// wrap a call to the C extern parents function | ||||
fn parents(&self, rev: Revision) -> Result<[Revision; 2], GraphError> { | ||||
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r41386 | if rev == WORKING_DIRECTORY_REVISION { | ||
return Err(GraphError::WorkingDirectoryUnsupported); | ||||
} | ||||
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r41082 | 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], | ||||
) | ||||
}; | ||||
match code { | ||||
0 => Ok(res), | ||||
_ => Err(GraphError::ParentOutOfRange(rev)), | ||||
} | ||||
} | ||||
} | ||||