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// Copyright (c) 2017-present PyO3 Project and Contributors // // based on Daniel Grunwald's https://github.com/dgrunwald/rust-cpython use crate::err::{PyDowncastError, PyErr, PyResult}; use crate::ffi; use crate::gil::{self, GILGuard}; use crate::instance::AsPyRef; use crate::object::PyObject; use crate::type_object::{PyDowncastImpl, PyTypeInfo, PyTypeObject}; use crate::types::{PyAny, PyDict, PyModule, PyType}; use crate::AsPyPointer; use crate::{FromPyPointer, IntoPyPointer, PyTryFrom}; use std::ffi::CString; use std::marker::PhantomData; use std::os::raw::c_int; use std::ptr::NonNull; pub use gil::prepare_freethreaded_python; /// Marker type that indicates that the GIL is currently held. /// /// The `Python` struct is a zero-sized marker struct that is required for most Python operations. /// This is used to indicate that the operation accesses/modifies the Python interpreter state, /// and thus can only be called if the Python interpreter is initialized and the /// Python global interpreter lock (GIL) is acquired. The lifetime `'p` represents the lifetime of /// holding the lock. /// /// Note that the GIL can be temporarily released by the Python interpreter during a function call /// (e.g. importing a module), even when you're holding a GILGuard. In general, you don't need to /// worry about this because the GIL is reacquired before returning to the Rust code: /// /// ```text /// `Python` exists |=====================================| /// GIL actually held |==========| |================| /// Rust code running |=======| |==| |======| /// ``` /// /// This behaviour can cause deadlocks when trying to lock a Rust mutex while /// holding the GIL: /// /// * Thread 1 acquires the GIL /// * Thread 1 locks a mutex /// * Thread 1 makes a call into the Python interpreter which releases the GIL /// * Thread 2 acquires the GIL /// * Thread 2 tries to locks the mutex, blocks /// * Thread 1's Python interpreter call blocks trying to reacquire the GIL held by thread 2 /// /// To avoid deadlocking, you should release the GIL before trying to lock a mutex, e.g. with /// [Python::allow_threads]. #[derive(Copy, Clone)] pub struct Python<'p>(PhantomData<&'p GILGuard>); impl<'p> Python<'p> { /// Retrieves a Python instance under the assumption that the GIL is already /// acquired at this point, and stays acquired for the lifetime `'p`. /// /// Because the output lifetime `'p` is not connected to any input parameter, /// care must be taken that the compiler infers an appropriate lifetime for `'p` /// when calling this function. #[inline] pub unsafe fn assume_gil_acquired() -> Python<'p> { Python(PhantomData) } /// Acquires the global interpreter lock, which allows access to the Python runtime. /// /// If the Python runtime is not already initialized, this function will initialize it. /// See [prepare_freethreaded_python()](fn.prepare_freethreaded_python.html) for details. #[inline] pub fn acquire_gil() -> GILGuard { GILGuard::acquire() } /// Temporarily releases the `GIL`, thus allowing other Python threads to run. /// /// # Example /// ``` /// # use pyo3::prelude::*; use pyo3::types::IntoPyDict; use pyo3::wrap_pyfunction; /// use pyo3::exceptions::RuntimeError; /// use std::sync::Arc; /// use std::thread; /// #[pyfunction] /// fn parallel_count(py: Python<'_>, strings: Vec<String>, query: String) -> PyResult<usize> { /// let query = query.chars().next().unwrap(); /// py.allow_threads(move || { /// let threads: Vec<_> = strings /// .into_iter() /// .map(|s| thread::spawn(move || s.chars().filter(|&c| c == query).count())) /// .collect(); /// let mut sum = 0; /// for t in threads { /// sum += t.join().map_err(|_| PyErr::new::<RuntimeError, _>(()))?; /// } /// Ok(sum) /// }) /// } /// let gil = Python::acquire_gil(); /// let py = gil.python(); /// let m = PyModule::new(py, "pcount").unwrap(); /// m.add_wrapped(wrap_pyfunction!(parallel_count)).unwrap(); /// let locals = [("pcount", m)].into_py_dict(py); /// py.run(r#" /// s = ["Flow", "my", "tears", "the", "Policeman", "Said"] /// assert pcount.parallel_count(s, "a") == 3 /// "#, None, Some(locals)); /// ``` /// /// **Note:** /// PyO3 types that represent objects with a lifetime tied to holding the GIL /// cannot be used in the closure. This includes `&PyAny` and all the /// concrete-typed siblings, like `&PyString`. /// /// You can convert such references to e.g. `PyObject` or `Py<PyString>`, /// which makes them independent of the GIL lifetime. However, you cannot /// do much with those without a `Python<'p>` token, for which you'd need to /// reacquire the GIL. /// /// # Example /// ```compile_fail /// # use pyo3::prelude::*; /// # use pyo3::types::PyString; /// fn parallel_print(py: Python<'_>) { /// let s = PyString::new(py, "This object should not be shared >_<"); /// py.allow_threads(move || { /// println!("{:?}", s); // This causes a compile error. /// }); /// } /// ``` pub fn allow_threads<T, F>(self, f: F) -> T where F: Send + FnOnce() -> T, { // The `Send` bound on the closure prevents the user from // transferring the `Python` token into the closure. unsafe { let save = ffi::PyEval_SaveThread(); let result = f(); ffi::PyEval_RestoreThread(save); result } } /// Evaluates a Python expression in the given context and returns the result. /// /// If `globals` is `None`, it defaults to Python module `__main__`. /// If `locals` is `None`, it defaults to the value of `globals`. /// /// # Example: /// ``` /// # use pyo3::{types::{PyBytes, PyDict}, prelude::*}; /// # let gil = pyo3::Python::acquire_gil(); /// # let py = gil.python(); /// let result = py.eval("[i * 10 for i in range(5)]", None, None).unwrap(); /// let res: Vec<i64> = result.extract().unwrap(); /// assert_eq!(res, vec![0, 10, 20, 30, 40]) /// ``` pub fn eval( self, code: &str, globals: Option<&PyDict>, locals: Option<&PyDict>, ) -> PyResult<&'p PyAny> { self.run_code(code, ffi::Py_eval_input, globals, locals) } /// Executes one or more Python statements in the given context. /// /// If `globals` is `None`, it defaults to Python module `__main__`. /// If `locals` is `None`, it defaults to the value of `globals`. /// /// # Example: /// ``` /// use pyo3::{types::{PyBytes, PyDict}, prelude::*}; /// let gil = pyo3::Python::acquire_gil(); /// let py = gil.python(); /// let locals = PyDict::new(py); /// py.run( /// r#" /// import base64 /// s = 'Hello Rust!' /// ret = base64.b64encode(s.encode('utf-8')) /// "#, /// None, /// Some(locals), /// ).unwrap(); /// let ret = locals.get_item("ret").unwrap(); /// let b64: &PyBytes = ret.downcast().unwrap(); /// assert_eq!(b64.as_bytes(), b"SGVsbG8gUnVzdCE="); /// ``` pub fn run( self, code: &str, globals: Option<&PyDict>, locals: Option<&PyDict>, ) -> PyResult<()> { let res = self.run_code(code, ffi::Py_file_input, globals, locals); res.map(|obj| { debug_assert!(crate::ObjectProtocol::is_none(obj)); }) } /// Runs code in the given context. /// /// `start` indicates the type of input expected: one of `Py_single_input`, /// `Py_file_input`, or `Py_eval_input`. /// /// If `globals` is `None`, it defaults to Python module `__main__`. /// If `locals` is `None`, it defaults to the value of `globals`. fn run_code( self, code: &str, start: c_int, globals: Option<&PyDict>, locals: Option<&PyDict>, ) -> PyResult<&'p PyAny> { let code = CString::new(code)?; unsafe { let mptr = ffi::PyImport_AddModule("__main__\0".as_ptr() as *const _); if mptr.is_null() { return Err(PyErr::fetch(self)); } let globals = globals .map(AsPyPointer::as_ptr) .unwrap_or_else(|| ffi::PyModule_GetDict(mptr)); let locals = locals.map(AsPyPointer::as_ptr).unwrap_or(globals); let res_ptr = ffi::PyRun_StringFlags( code.as_ptr(), start, globals, locals, ::std::ptr::null_mut(), ); self.from_owned_ptr_or_err(res_ptr) } } /// Gets the Python type object for type `T`. pub fn get_type<T>(self) -> &'p PyType where T: PyTypeObject, { unsafe { self.from_borrowed_ptr(T::type_object().into_ptr()) } } /// Imports the Python module with the specified name. pub fn import(self, name: &str) -> PyResult<&'p PyModule> { PyModule::import(self, name) } /// Checks whether `obj` is an instance of type `T`. /// /// This is equivalent to the Python `isinstance` function. pub fn is_instance<T: PyTypeObject, V: AsPyPointer>(self, obj: &V) -> PyResult<bool> { T::type_object().as_ref(self).is_instance(obj) } /// Checks whether type `T` is subclass of type `U`. /// /// This is equivalent to the Python `issubclass` function. pub fn is_subclass<T, U>(self) -> PyResult<bool> where T: PyTypeObject, U: PyTypeObject, { T::type_object().as_ref(self).is_subclass::<U>() } /// Gets the Python builtin value `None`. #[allow(non_snake_case)] // the Python keyword starts with uppercase #[inline] pub fn None(self) -> PyObject { unsafe { PyObject::from_borrowed_ptr(self, ffi::Py_None()) } } /// Gets the Python builtin value `NotImplemented`. #[allow(non_snake_case)] // the Python keyword starts with uppercase #[inline] pub fn NotImplemented(self) -> PyObject { unsafe { PyObject::from_borrowed_ptr(self, ffi::Py_NotImplemented()) } } } impl<'p> Python<'p> { /// Registers the object in the release pool, and tries to downcast to specific type. pub fn checked_cast_as<T>(self, obj: PyObject) -> Result<&'p T, PyDowncastError> where T: PyTryFrom<'p>, { let obj = unsafe { gil::register_owned(self, obj.into_nonnull()) }; <T as PyTryFrom>::try_from(obj) } /// Registers the object in the release pool, and does an unchecked downcast /// to the specific type. pub unsafe fn cast_as<T>(self, obj: PyObject) -> &'p T where T: PyDowncastImpl + PyTypeInfo, { let obj = gil::register_owned(self, obj.into_nonnull()); T::unchecked_downcast(obj) } /// Registers the object pointer in the release pool. #[allow(clippy::wrong_self_convention)] pub unsafe fn from_borrowed_ptr_to_obj(self, ptr: *mut ffi::PyObject) -> &'p PyAny { match NonNull::new(ptr) { Some(p) => gil::register_borrowed(self, p), None => crate::err::panic_after_error(), } } /// Registers the object pointer in the release pool, /// and does an unchecked downcast to the specific type. #[allow(clippy::wrong_self_convention)] pub unsafe fn from_owned_ptr<T>(self, ptr: *mut ffi::PyObject) -> &'p T where T: FromPyPointer<'p>, { FromPyPointer::from_owned_ptr(self, ptr) } /// Registers the owned object pointer in the release pool. /// /// Returns `Err(PyErr)` if the pointer is NULL. /// Does an unchecked downcast to the specific type. #[allow(clippy::wrong_self_convention)] pub unsafe fn from_owned_ptr_or_err<T>(self, ptr: *mut ffi::PyObject) -> PyResult<&'p T> where T: FromPyPointer<'p>, { FromPyPointer::from_owned_ptr_or_err(self, ptr) } /// Registers the owned object pointer in release pool. /// /// Returns `None` if the pointer is NULL. /// Does an unchecked downcast to the specific type. #[allow(clippy::wrong_self_convention)] pub unsafe fn from_owned_ptr_or_opt<T>(self, ptr: *mut ffi::PyObject) -> Option<&'p T> where T: FromPyPointer<'p>, { FromPyPointer::from_owned_ptr_or_opt(self, ptr) } /// Registers the borrowed object pointer in the release pool. /// /// Panics if the pointer is NULL. /// Does an unchecked downcast to the specific type. #[allow(clippy::wrong_self_convention)] pub unsafe fn from_borrowed_ptr<T>(self, ptr: *mut ffi::PyObject) -> &'p T where T: FromPyPointer<'p>, { FromPyPointer::from_borrowed_ptr(self, ptr) } /// Registers the borrowed object pointer in the release pool. /// /// Returns `Err(PyErr)` if the pointer is NULL. /// Does an unchecked downcast to the specific type. #[allow(clippy::wrong_self_convention)] pub unsafe fn from_borrowed_ptr_or_err<T>(self, ptr: *mut ffi::PyObject) -> PyResult<&'p T> where T: FromPyPointer<'p>, { FromPyPointer::from_borrowed_ptr_or_err(self, ptr) } /// Registers the borrowed object pointer in the release pool. /// /// Returns `None` if the pointer is NULL. /// Does an unchecked downcast to the specific type. #[allow(clippy::wrong_self_convention)] pub unsafe fn from_borrowed_ptr_or_opt<T>(self, ptr: *mut ffi::PyObject) -> Option<&'p T> where T: FromPyPointer<'p>, { FromPyPointer::from_borrowed_ptr_or_opt(self, ptr) } #[doc(hidden)] /// Passes value ownership to `Python` object and get reference back. /// Value get cleaned up on the GIL release. pub fn register_any<T: 'static>(self, ob: T) -> &'p T { unsafe { gil::register_any(ob) } } /// Releases a PyObject reference. #[inline] pub fn release<T>(self, ob: T) where T: IntoPyPointer, { unsafe { let ptr = ob.into_ptr(); if !ptr.is_null() { ffi::Py_DECREF(ptr); } } } /// Releases a `ffi::PyObject` pointer. #[inline] pub fn xdecref<T: IntoPyPointer>(self, ptr: T) { unsafe { ffi::Py_XDECREF(ptr.into_ptr()) }; } } #[cfg(test)] mod test { use crate::objectprotocol::ObjectProtocol; use crate::types::{IntoPyDict, PyAny, PyBool, PyInt, PyList}; use crate::Python; #[test] fn test_eval() { let gil = Python::acquire_gil(); let py = gil.python(); // Make sure builtin names are accessible let v: i32 = py .eval("min(1, 2)", None, None) .map_err(|e| e.print(py)) .unwrap() .extract() .unwrap(); assert_eq!(v, 1); let d = [("foo", 13)].into_py_dict(py); // Inject our own global namespace let v: i32 = py .eval("foo + 29", Some(d), None) .unwrap() .extract() .unwrap(); assert_eq!(v, 42); // Inject our own local namespace let v: i32 = py .eval("foo + 29", None, Some(d)) .unwrap() .extract() .unwrap(); assert_eq!(v, 42); // Make sure builtin names are still accessible when using a local namespace let v: i32 = py .eval("min(foo, 2)", None, Some(d)) .unwrap() .extract() .unwrap(); assert_eq!(v, 2); } #[test] fn test_is_instance() { let gil = Python::acquire_gil(); let py = gil.python(); assert!(py .is_instance::<PyBool, PyAny>(PyBool::new(py, true).into()) .unwrap()); let list = PyList::new(py, &[1, 2, 3, 4]); assert!(!py.is_instance::<PyBool, _>(list.as_ref()).unwrap()); assert!(py.is_instance::<PyList, _>(list.as_ref()).unwrap()); } #[test] fn test_is_subclass() { let gil = Python::acquire_gil(); let py = gil.python(); assert!(py.is_subclass::<PyBool, PyInt>().unwrap()); assert!(!py.is_subclass::<PyBool, PyList>().unwrap()); } }