diff options
Diffstat (limited to 'include/jvmaccess/virtualmachine.hxx')
| -rw-r--r-- | include/jvmaccess/virtualmachine.hxx | 154 |
1 files changed, 154 insertions, 0 deletions
diff --git a/include/jvmaccess/virtualmachine.hxx b/include/jvmaccess/virtualmachine.hxx new file mode 100644 index 000000000..e1286e700 --- /dev/null +++ b/include/jvmaccess/virtualmachine.hxx @@ -0,0 +1,154 @@ +/* -*- 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: */ |