pyLock.h

//
// Copyright 2016 Pixar
//
// Licensed under the Apache License, Version 2.0 (the "Apache License")
// with the following modification; you may not use this file except in
// compliance with the Apache License and the following modification to it:
// Section 6. Trademarks. is deleted and replaced with:
//
// 6. Trademarks. This License does not grant permission to use the trade
//    names, trademarks, service marks, or product names of the Licensor
//    and its affiliates, except as required to comply with Section 4(c) of
//    the License and to reproduce the content of the NOTICE file.
//
// You may obtain a copy of the Apache License at
//
//     http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the Apache License with the above modification is
// distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
// KIND, either express or implied. See the Apache License for the specific
// language governing permissions and limitations under the Apache License.
//
#ifndef PXR_BASE_TF_PY_LOCK_H
#define PXR_BASE_TF_PY_LOCK_H

#include "pxr/pxr.h"

#ifdef PXR_PYTHON_SUPPORT_ENABLED

#include "pxr/base/tf/pySafePython.h"

#include "pxr/base/tf/api.h"

PXR_NAMESPACE_OPEN_SCOPE

class TfPyLock {
public:
    TF_API TfPyLock();

    TF_API ~TfPyLock();

    TF_API void Acquire();

    TF_API void Release();

    TF_API void BeginAllowThreads();

    TF_API void EndAllowThreads();

private:
    // Non-acquiring constructor for TfPyEnsureGILUnlockedObj's use.
    friend struct TfPyEnsureGILUnlockedObj;
    enum _UnlockedTag { _ConstructUnlocked };
    explicit TfPyLock(_UnlockedTag);

    PyGILState_STATE _gilState;
    PyThreadState *_savedState;
    bool _acquired:1;
    bool _allowingThreads:1;
};

// Helper class for TF_PY_ALLOW_THREADS_IN_SCOPE()
struct TfPyEnsureGILUnlockedObj
{
    // Do nothing if the current thread does not have the GIL, otherwise unlock
    // the GIL, and relock upon destruction.
    TF_API TfPyEnsureGILUnlockedObj();
private:
    TfPyLock _lock;
};

#define TF_PY_ALLOW_THREADS_IN_SCOPE()                  \
    TfPyEnsureGILUnlockedObj __py_lock_allow_threads__

PXR_NAMESPACE_CLOSE_SCOPE

#else 

// When python is disabled, we stub this macro out to nothing.
#define TF_PY_ALLOW_THREADS_IN_SCOPE()

#endif // PXR_PYTHON_SUPPORT_ENABLED

#endif // PXR_BASE_TF_PY_LOCK_H