rust/hg-cpython/src/pybytes_deref.rs
author Georges Racinet <georges.racinet@octobus.net>
Wed, 18 Oct 2023 19:54:18 +0200
changeset 51196 44fbb7dfb563
parent 49933 be3b545c5cff
child 52163 7346f93be7a4
permissions -rw-r--r--
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.
Ignore whitespace changes - Everywhere: Within whitespace: At end of lines:
47953
8f031a274cd6 rust: Move PyBytesWithData out of copy-tracing code
Simon Sapin <simon.sapin@octobus.net>
parents:
diff changeset
     1
use cpython::{PyBytes, Python};
47954
4afd6cc447b9 rust: Make OwningDirstateMap generic and move it into hg-core
Simon Sapin <simon.sapin@octobus.net>
parents: 47953
diff changeset
     2
use stable_deref_trait::StableDeref;
47953
8f031a274cd6 rust: Move PyBytesWithData out of copy-tracing code
Simon Sapin <simon.sapin@octobus.net>
parents:
diff changeset
     3
8f031a274cd6 rust: Move PyBytesWithData out of copy-tracing code
Simon Sapin <simon.sapin@octobus.net>
parents:
diff changeset
     4
/// Safe abstraction over a `PyBytes` together with the `&[u8]` slice
8f031a274cd6 rust: Move PyBytesWithData out of copy-tracing code
Simon Sapin <simon.sapin@octobus.net>
parents:
diff changeset
     5
/// that borrows it. Implements `Deref<Target = [u8]>`.
8f031a274cd6 rust: Move PyBytesWithData out of copy-tracing code
Simon Sapin <simon.sapin@octobus.net>
parents:
diff changeset
     6
///
8f031a274cd6 rust: Move PyBytesWithData out of copy-tracing code
Simon Sapin <simon.sapin@octobus.net>
parents:
diff changeset
     7
/// Calling `PyBytes::data` requires a GIL marker but we want to access the
8f031a274cd6 rust: Move PyBytesWithData out of copy-tracing code
Simon Sapin <simon.sapin@octobus.net>
parents:
diff changeset
     8
/// data in a thread that (ideally) does not need to acquire the GIL.
8f031a274cd6 rust: Move PyBytesWithData out of copy-tracing code
Simon Sapin <simon.sapin@octobus.net>
parents:
diff changeset
     9
/// This type allows separating the call an the use.
8f031a274cd6 rust: Move PyBytesWithData out of copy-tracing code
Simon Sapin <simon.sapin@octobus.net>
parents:
diff changeset
    10
///
8f031a274cd6 rust: Move PyBytesWithData out of copy-tracing code
Simon Sapin <simon.sapin@octobus.net>
parents:
diff changeset
    11
/// It also enables using a (wrapped) `PyBytes` in GIL-unaware generic code.
8f031a274cd6 rust: Move PyBytesWithData out of copy-tracing code
Simon Sapin <simon.sapin@octobus.net>
parents:
diff changeset
    12
pub struct PyBytesDeref {
8f031a274cd6 rust: Move PyBytesWithData out of copy-tracing code
Simon Sapin <simon.sapin@octobus.net>
parents:
diff changeset
    13
    #[allow(unused)]
8f031a274cd6 rust: Move PyBytesWithData out of copy-tracing code
Simon Sapin <simon.sapin@octobus.net>
parents:
diff changeset
    14
    keep_alive: PyBytes,
8f031a274cd6 rust: Move PyBytesWithData out of copy-tracing code
Simon Sapin <simon.sapin@octobus.net>
parents:
diff changeset
    15
8f031a274cd6 rust: Move PyBytesWithData out of copy-tracing code
Simon Sapin <simon.sapin@octobus.net>
parents:
diff changeset
    16
    /// Borrows the buffer inside `self.keep_alive`,
8f031a274cd6 rust: Move PyBytesWithData out of copy-tracing code
Simon Sapin <simon.sapin@octobus.net>
parents:
diff changeset
    17
    /// but the borrow-checker cannot express self-referential structs.
8f031a274cd6 rust: Move PyBytesWithData out of copy-tracing code
Simon Sapin <simon.sapin@octobus.net>
parents:
diff changeset
    18
    data: *const [u8],
8f031a274cd6 rust: Move PyBytesWithData out of copy-tracing code
Simon Sapin <simon.sapin@octobus.net>
parents:
diff changeset
    19
}
8f031a274cd6 rust: Move PyBytesWithData out of copy-tracing code
Simon Sapin <simon.sapin@octobus.net>
parents:
diff changeset
    20
8f031a274cd6 rust: Move PyBytesWithData out of copy-tracing code
Simon Sapin <simon.sapin@octobus.net>
parents:
diff changeset
    21
impl PyBytesDeref {
8f031a274cd6 rust: Move PyBytesWithData out of copy-tracing code
Simon Sapin <simon.sapin@octobus.net>
parents:
diff changeset
    22
    pub fn new(py: Python, bytes: PyBytes) -> Self {
8f031a274cd6 rust: Move PyBytesWithData out of copy-tracing code
Simon Sapin <simon.sapin@octobus.net>
parents:
diff changeset
    23
        Self {
8f031a274cd6 rust: Move PyBytesWithData out of copy-tracing code
Simon Sapin <simon.sapin@octobus.net>
parents:
diff changeset
    24
            data: bytes.data(py),
8f031a274cd6 rust: Move PyBytesWithData out of copy-tracing code
Simon Sapin <simon.sapin@octobus.net>
parents:
diff changeset
    25
            keep_alive: bytes,
8f031a274cd6 rust: Move PyBytesWithData out of copy-tracing code
Simon Sapin <simon.sapin@octobus.net>
parents:
diff changeset
    26
        }
8f031a274cd6 rust: Move PyBytesWithData out of copy-tracing code
Simon Sapin <simon.sapin@octobus.net>
parents:
diff changeset
    27
    }
8f031a274cd6 rust: Move PyBytesWithData out of copy-tracing code
Simon Sapin <simon.sapin@octobus.net>
parents:
diff changeset
    28
8f031a274cd6 rust: Move PyBytesWithData out of copy-tracing code
Simon Sapin <simon.sapin@octobus.net>
parents:
diff changeset
    29
    pub fn unwrap(self) -> PyBytes {
8f031a274cd6 rust: Move PyBytesWithData out of copy-tracing code
Simon Sapin <simon.sapin@octobus.net>
parents:
diff changeset
    30
        self.keep_alive
8f031a274cd6 rust: Move PyBytesWithData out of copy-tracing code
Simon Sapin <simon.sapin@octobus.net>
parents:
diff changeset
    31
    }
8f031a274cd6 rust: Move PyBytesWithData out of copy-tracing code
Simon Sapin <simon.sapin@octobus.net>
parents:
diff changeset
    32
}
8f031a274cd6 rust: Move PyBytesWithData out of copy-tracing code
Simon Sapin <simon.sapin@octobus.net>
parents:
diff changeset
    33
8f031a274cd6 rust: Move PyBytesWithData out of copy-tracing code
Simon Sapin <simon.sapin@octobus.net>
parents:
diff changeset
    34
impl std::ops::Deref for PyBytesDeref {
8f031a274cd6 rust: Move PyBytesWithData out of copy-tracing code
Simon Sapin <simon.sapin@octobus.net>
parents:
diff changeset
    35
    type Target = [u8];
8f031a274cd6 rust: Move PyBytesWithData out of copy-tracing code
Simon Sapin <simon.sapin@octobus.net>
parents:
diff changeset
    36
8f031a274cd6 rust: Move PyBytesWithData out of copy-tracing code
Simon Sapin <simon.sapin@octobus.net>
parents:
diff changeset
    37
    fn deref(&self) -> &[u8] {
8f031a274cd6 rust: Move PyBytesWithData out of copy-tracing code
Simon Sapin <simon.sapin@octobus.net>
parents:
diff changeset
    38
        // Safety: the raw pointer is valid as long as the PyBytes is still
8f031a274cd6 rust: Move PyBytesWithData out of copy-tracing code
Simon Sapin <simon.sapin@octobus.net>
parents:
diff changeset
    39
        // alive, and the returned slice borrows `self`.
8f031a274cd6 rust: Move PyBytesWithData out of copy-tracing code
Simon Sapin <simon.sapin@octobus.net>
parents:
diff changeset
    40
        unsafe { &*self.data }
8f031a274cd6 rust: Move PyBytesWithData out of copy-tracing code
Simon Sapin <simon.sapin@octobus.net>
parents:
diff changeset
    41
    }
8f031a274cd6 rust: Move PyBytesWithData out of copy-tracing code
Simon Sapin <simon.sapin@octobus.net>
parents:
diff changeset
    42
}
8f031a274cd6 rust: Move PyBytesWithData out of copy-tracing code
Simon Sapin <simon.sapin@octobus.net>
parents:
diff changeset
    43
47954
4afd6cc447b9 rust: Make OwningDirstateMap generic and move it into hg-core
Simon Sapin <simon.sapin@octobus.net>
parents: 47953
diff changeset
    44
unsafe impl StableDeref for PyBytesDeref {}
4afd6cc447b9 rust: Make OwningDirstateMap generic and move it into hg-core
Simon Sapin <simon.sapin@octobus.net>
parents: 47953
diff changeset
    45
47953
8f031a274cd6 rust: Move PyBytesWithData out of copy-tracing code
Simon Sapin <simon.sapin@octobus.net>
parents:
diff changeset
    46
fn require_send<T: Send>() {}
8f031a274cd6 rust: Move PyBytesWithData out of copy-tracing code
Simon Sapin <simon.sapin@octobus.net>
parents:
diff changeset
    47
8f031a274cd6 rust: Move PyBytesWithData out of copy-tracing code
Simon Sapin <simon.sapin@octobus.net>
parents:
diff changeset
    48
#[allow(unused)]
8f031a274cd6 rust: Move PyBytesWithData out of copy-tracing code
Simon Sapin <simon.sapin@octobus.net>
parents:
diff changeset
    49
fn static_assert_pybytes_is_send() {
49933
be3b545c5cff rust-clippy: fix remaining warnings in `hg-cpython`
Rapha?l Gom?s <rgomes@octobus.net>
parents: 47954
diff changeset
    50
    #[allow(clippy::no_effect)]
47953
8f031a274cd6 rust: Move PyBytesWithData out of copy-tracing code
Simon Sapin <simon.sapin@octobus.net>
parents:
diff changeset
    51
    require_send::<PyBytes>;
8f031a274cd6 rust: Move PyBytesWithData out of copy-tracing code
Simon Sapin <simon.sapin@octobus.net>
parents:
diff changeset
    52
}
8f031a274cd6 rust: Move PyBytesWithData out of copy-tracing code
Simon Sapin <simon.sapin@octobus.net>
parents:
diff changeset
    53
8f031a274cd6 rust: Move PyBytesWithData out of copy-tracing code
Simon Sapin <simon.sapin@octobus.net>
parents:
diff changeset
    54
// Safety: PyBytes is Send. Raw pointers are not by default,
8f031a274cd6 rust: Move PyBytesWithData out of copy-tracing code
Simon Sapin <simon.sapin@octobus.net>
parents:
diff changeset
    55
// but here sending one to another thread is fine since we ensure it stays
8f031a274cd6 rust: Move PyBytesWithData out of copy-tracing code
Simon Sapin <simon.sapin@octobus.net>
parents:
diff changeset
    56
// valid.
8f031a274cd6 rust: Move PyBytesWithData out of copy-tracing code
Simon Sapin <simon.sapin@octobus.net>
parents:
diff changeset
    57
unsafe impl Send for PyBytesDeref {}