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/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
/*
* This file is part of the LibreOffice project.
*
* This Source Code Form is subject to the terms of the Mozilla Public
* License, v. 2.0. If a copy of the MPL was not distributed with this
* file, You can obtain one at http://mozilla.org/MPL/2.0/.
*
* This file incorporates work covered by the following license notice:
*
* 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 .
*/
#ifndef INCLUDED_JVMACCESS_VIRTUALMACHINE_HXX
#define INCLUDED_JVMACCESS_VIRTUALMACHINE_HXX
#include <jvmaccess/jvmaccessdllapi.h>
#include <rtl/ref.hxx>
#include <salhelper/simplereferenceobject.hxx>
#if defined __clang__
#pragma clang diagnostic push
#pragma clang diagnostic ignored "-Wunknown-attributes"
#endif
#include <jni.h>
#if defined __clang__
#pragma clang diagnostic pop
#endif
namespace jvmaccess
{
/** An encapsulating wrapper around a Java virtual machine.
*/
class JVMACCESS_DLLPUBLIC VirtualMachine final : public salhelper::SimpleReferenceObject
{
public:
/** A helper to attach a thread to a Java virtual machine.
@descr
Upon construction of a guard the current thread is attached to the
virtual machine, and upon destruction of the guard the thread is
detached again. For any one thread, multiple instances of this class
may be used in a stack-like fashion (care is taken to only really
detach the thread from the virtual machine upon destruction of the guard
at the bottom of the stack).
*/
class JVMACCESS_DLLPUBLIC AttachGuard
{
public:
/** An exception indicating failure to create an AttachGuard.
*/
class JVMACCESS_DLLPUBLIC CreationException final
{
public:
CreationException();
CreationException(CreationException const&);
CreationException& operator=(CreationException const&);
};
/** Attach the current thread to a virtual machine.
@param rMachine
The virtual machine to attach to. Must not be a null reference.
@exception CreationException
Thrown in case attaching fails (due to a JNI problem).
*/
explicit AttachGuard(rtl::Reference<VirtualMachine> xMachine);
/** Detach the current thread from the virtual machine again.
*/
~AttachGuard();
/** Get a JNI environment pointer for the current thread.
@return
A valid JNI environment pointer. Will never be null.
*/
JNIEnv* getEnvironment() const { return m_pEnvironment; }
private:
AttachGuard(AttachGuard const&) = delete;
AttachGuard& operator=(AttachGuard const&) = delete;
rtl::Reference<VirtualMachine> m_xMachine;
JNIEnv* m_pEnvironment;
bool m_bDetach;
};
/** Create a wrapper around a Java virtual machine.
@param pVm
A JNI pointer to virtual machine. Must not be null.
@param nVersion
The JNI version of the virtual machine pointed to by pVm. Must be at
least JNI_VERSION_1_2. This parameter should be of type jint, not int,
but at least on some platforms the definition of jint changed from
JDK 1.3 (long) to JDK 1.4 (int), so that the mangled C++ name of the
constructor would depend on the JDK version used at compile time.
@param bDestroy
Whether to destroy the virtual machine when destructing the wrapper
(i.e., whether the wrapper owns the virtual machine pointed to by pVm).
@param pMainThreadEnv
A valid JNI environment pointer for the current thread; must not be
null. The current thread must be "initially attached" to the virtual
machine while this constructor is being called (i.e., it must be the
thread that has called JNI_CreateJavaVM in case the virtual machine has
been started via the JNI Invocation API, and it must not already have
called DetachCurrentThread; or it must be executing native code called
from a "primordial" virtual machine). This environment pointer was
formerly used to obtain a reference to the thread's current context
class loader (java.lang.Thread.getCurrentClassLoader; if later a native
thread was attached to the virtual machine, that thread's context class
loader would be null, so the AttachGuard first of all set it to the
saved value; this feature has been removed again for performance reasons
and because the default context class loader is often not useful, so
that code relying on a context class loader has to set one explicitly,
anyway). This parameter is currently unused (but may be used again in
the future).
*/
VirtualMachine(JavaVM* pVm, int nVersion, bool bDestroy, JNIEnv const* pMainThreadEnv);
private:
VirtualMachine(VirtualMachine const&) = delete;
VirtualMachine& operator=(VirtualMachine const&) = delete;
virtual ~VirtualMachine() override;
JNIEnv* attachThread(bool* pAttached) const;
void detachThread() const;
JavaVM* m_pVm;
jint m_nVersion;
bool m_bDestroy;
friend class AttachGuard; // to access attachThread, detachThread
};
}
#endif // INCLUDED_JVMACCESS_VIRTUALMACHINE_HXX
/* vim:set shiftwidth=4 softtabstop=4 expandtab: */
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