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311 lines (258 loc) · 9.13 KB
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// Licensed to the Apache Software Foundation (ASF) under one
// or more contributor license agreements. See the NOTICE file
// distributed with this work for additional information
// regarding copyright ownership. The ASF licenses this file
// to you under the Apache License, Version 2.0 (the
// "License"); you may not use this file except in compliance
// with the License. You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing,
// software distributed under the License is distributed on an
// "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
// KIND, either express or implied. See the License for the
// specific language governing permissions and limitations
// under the License.
#ifndef ARROW_PYTHON_COMMON_H
#define ARROW_PYTHON_COMMON_H
#include <memory>
#include <utility>
#include "arrow/python/config.h"
#include "arrow/buffer.h"
#include "arrow/python/pyarrow.h"
#include "arrow/python/visibility.h"
#include "arrow/util/macros.h"
namespace arrow {
class MemoryPool;
template <class T>
class Result;
namespace py {
// Convert current Python error to a Status. The Python error state is cleared
// and can be restored with RestorePyError().
ARROW_PYTHON_EXPORT Status ConvertPyError(StatusCode code = StatusCode::UnknownError);
// Same as ConvertPyError(), but returns Status::OK() if no Python error is set.
ARROW_PYTHON_EXPORT Status PassPyError();
// Query whether the given Status is a Python error (as wrapped by ConvertPyError()).
ARROW_PYTHON_EXPORT bool IsPyError(const Status& status);
// Restore a Python error wrapped in a Status.
ARROW_PYTHON_EXPORT void RestorePyError(const Status& status);
// Catch a pending Python exception and return the corresponding Status.
// If no exception is pending, Status::OK() is returned.
inline Status CheckPyError(StatusCode code = StatusCode::UnknownError) {
if (ARROW_PREDICT_TRUE(!PyErr_Occurred())) {
return Status::OK();
} else {
return ConvertPyError(code);
}
}
#define RETURN_IF_PYERROR() ARROW_RETURN_NOT_OK(CheckPyError());
#define PY_RETURN_IF_ERROR(CODE) ARROW_RETURN_NOT_OK(CheckPyError(CODE));
// For Cython, as you can't define template C++ functions in Cython, only use them.
// This function can set a Python exception. It assumes that T has a (cheap)
// default constructor.
template <class T>
T GetResultValue(Result<T>& result) {
if (ARROW_PREDICT_TRUE(result.ok())) {
return *std::move(result);
} else {
int r = internal::check_status(result.status());
assert(r == -1); // should have errored out
ARROW_UNUSED(r);
return {};
}
}
// A RAII-style helper that ensures the GIL is acquired inside a lexical block.
class ARROW_PYTHON_EXPORT PyAcquireGIL {
public:
PyAcquireGIL() : acquired_gil_(false) { acquire(); }
~PyAcquireGIL() { release(); }
void acquire() {
if (!acquired_gil_) {
state_ = PyGILState_Ensure();
acquired_gil_ = true;
}
}
// idempotent
void release() {
if (acquired_gil_) {
PyGILState_Release(state_);
acquired_gil_ = false;
}
}
private:
bool acquired_gil_;
PyGILState_STATE state_;
ARROW_DISALLOW_COPY_AND_ASSIGN(PyAcquireGIL);
};
// A RAII-style helper that releases the GIL until the end of a lexical block
class ARROW_PYTHON_EXPORT PyReleaseGIL {
public:
PyReleaseGIL() { saved_state_ = PyEval_SaveThread(); }
~PyReleaseGIL() { PyEval_RestoreThread(saved_state_); }
private:
PyThreadState* saved_state_;
ARROW_DISALLOW_COPY_AND_ASSIGN(PyReleaseGIL);
};
// A helper to call safely into the Python interpreter from arbitrary C++ code.
// The GIL is acquired, and the current thread's error status is preserved.
template <typename Function>
Status SafeCallIntoPython(Function&& func) {
PyAcquireGIL lock;
PyObject* exc_type;
PyObject* exc_value;
PyObject* exc_traceback;
PyErr_Fetch(&exc_type, &exc_value, &exc_traceback);
Status st = std::forward<Function>(func)();
// If the return Status is a "Python error", the current Python error status
// describes the error and shouldn't be clobbered.
if (!IsPyError(st) && exc_type != NULLPTR) {
PyErr_Restore(exc_type, exc_value, exc_traceback);
}
return st;
}
#define PYARROW_IS_PY2 PY_MAJOR_VERSION <= 2
// A RAII primitive that DECREFs the underlying PyObject* when it
// goes out of scope.
class ARROW_PYTHON_EXPORT OwnedRef {
public:
OwnedRef() : obj_(NULLPTR) {}
OwnedRef(OwnedRef&& other) : OwnedRef(other.detach()) {}
explicit OwnedRef(PyObject* obj) : obj_(obj) {}
OwnedRef& operator=(OwnedRef&& other) {
obj_ = other.detach();
return *this;
}
~OwnedRef() { reset(); }
void reset(PyObject* obj) {
Py_XDECREF(obj_);
obj_ = obj;
}
void reset() { reset(NULLPTR); }
PyObject* detach() {
PyObject* result = obj_;
obj_ = NULLPTR;
return result;
}
PyObject* obj() const { return obj_; }
PyObject** ref() { return &obj_; }
operator bool() const { return obj_ != NULLPTR; }
private:
ARROW_DISALLOW_COPY_AND_ASSIGN(OwnedRef);
PyObject* obj_;
};
// Same as OwnedRef, but ensures the GIL is taken when it goes out of scope.
// This is for situations where the GIL is not always known to be held
// (e.g. if it is released in the middle of a function for performance reasons)
class ARROW_PYTHON_EXPORT OwnedRefNoGIL : public OwnedRef {
public:
OwnedRefNoGIL() : OwnedRef() {}
OwnedRefNoGIL(OwnedRefNoGIL&& other) : OwnedRef(other.detach()) {}
explicit OwnedRefNoGIL(PyObject* obj) : OwnedRef(obj) {}
~OwnedRefNoGIL() {
PyAcquireGIL lock;
reset();
}
};
// A temporary conversion of a Python object to a bytes area.
struct PyBytesView {
const char* bytes;
Py_ssize_t size;
PyBytesView() : bytes(NULLPTR), size(0), ref(NULLPTR) {}
// View the given Python object as binary-like, i.e. bytes
Status FromBinary(PyObject* obj) { return FromBinary(obj, "a bytes object"); }
Status FromString(PyObject* obj) {
bool ignored = false;
return FromString(obj, false, &ignored);
}
Status FromString(PyObject* obj, bool* is_utf8) {
return FromString(obj, true, is_utf8);
}
Status FromUnicode(PyObject* obj) {
#if PY_MAJOR_VERSION >= 3
Py_ssize_t size;
// The utf-8 representation is cached on the unicode object
const char* data = PyUnicode_AsUTF8AndSize(obj, &size);
RETURN_IF_PYERROR();
this->bytes = data;
this->size = size;
this->ref.reset();
#else
PyObject* converted = PyUnicode_AsUTF8String(obj);
RETURN_IF_PYERROR();
this->bytes = PyBytes_AS_STRING(converted);
this->size = PyBytes_GET_SIZE(converted);
this->ref.reset(converted);
#endif
return Status::OK();
}
protected:
PyBytesView(const char* b, Py_ssize_t s, PyObject* obj = NULLPTR)
: bytes(b), size(s), ref(obj) {}
// View the given Python object as string-like, i.e. str or (utf8) bytes
Status FromString(PyObject* obj, bool check_utf8, bool* is_utf8) {
if (PyUnicode_Check(obj)) {
*is_utf8 = true;
return FromUnicode(obj);
} else {
ARROW_RETURN_NOT_OK(FromBinary(obj, "a string or bytes object"));
if (check_utf8) {
// Check the bytes are utf8 utf-8
OwnedRef decoded(PyUnicode_FromStringAndSize(bytes, size));
if (ARROW_PREDICT_TRUE(!PyErr_Occurred())) {
*is_utf8 = true;
} else {
*is_utf8 = false;
PyErr_Clear();
}
} else {
*is_utf8 = false;
}
return Status::OK();
}
}
Status FromBinary(PyObject* obj, const char* expected_msg) {
if (PyBytes_Check(obj)) {
this->bytes = PyBytes_AS_STRING(obj);
this->size = PyBytes_GET_SIZE(obj);
this->ref.reset();
return Status::OK();
} else if (PyByteArray_Check(obj)) {
this->bytes = PyByteArray_AS_STRING(obj);
this->size = PyByteArray_GET_SIZE(obj);
this->ref.reset();
return Status::OK();
} else {
return Status::TypeError("Expected ", expected_msg, ", got a '",
Py_TYPE(obj)->tp_name, "' object");
}
}
OwnedRef ref;
};
// Return the common PyArrow memory pool
ARROW_PYTHON_EXPORT void set_default_memory_pool(MemoryPool* pool);
ARROW_PYTHON_EXPORT MemoryPool* get_memory_pool();
class ARROW_PYTHON_EXPORT PyBuffer : public Buffer {
public:
/// While memoryview objects support multi-dimensional buffers, PyBuffer only supports
/// one-dimensional byte buffers.
~PyBuffer();
static Status FromPyObject(PyObject* obj, std::shared_ptr<Buffer>* out);
private:
PyBuffer();
Status Init(PyObject*);
Py_buffer py_buf_;
};
// This is annoying: because C++11 does not allow implicit conversion of string
// literals to non-const char*, we need to go through some gymnastics to use
// PyObject_CallMethod without a lot of pain (its arguments are non-const
// char*)
template <typename... ArgTypes>
static inline PyObject* cpp_PyObject_CallMethod(PyObject* obj, const char* method_name,
const char* argspec, ArgTypes... args) {
return PyObject_CallMethod(obj, const_cast<char*>(method_name),
const_cast<char*>(argspec), args...);
}
} // namespace py
} // namespace arrow
#endif // ARROW_PYTHON_COMMON_H