Java example source code file (interfaceSupport.hpp)

This example Java source code file (interfaceSupport.hpp) is included in the alvinalexander.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" ^TM.

Learn more about this Java project at its project page.

Java - Java tags/keywords

handlemarkcleaner, javathread, javathreadstate, jnicall, runtimehistogramelement, thread\:\:current, threadinvmfromjava, threadinvmfromjavanoasyncexception, threadinvmfromnative, threadstatetransition, trace_call, vm_entry_base, vm_leaf_base

The interfaceSupport.hpp Java example source code

/*
 * Copyright (c) 1997, 2013, Oracle and/or its affiliates. All rights reserved.
 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
 *
 * This code is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License version 2 only, as
 * published by the Free Software Foundation.
 *
 * This code is distributed in the hope that it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
 * version 2 for more details (a copy is included in the LICENSE file that
 * accompanied this code).
 *
 * You should have received a copy of the GNU General Public License version
 * 2 along with this work; if not, write to the Free Software Foundation,
 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
 *
 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
 * or visit www.oracle.com if you need additional information or have any
 * questions.
 *
 */

#ifndef SHARE_VM_RUNTIME_INTERFACESUPPORT_HPP
#define SHARE_VM_RUNTIME_INTERFACESUPPORT_HPP

#include "memory/gcLocker.hpp"
#include "runtime/handles.inline.hpp"
#include "runtime/mutexLocker.hpp"
#include "runtime/orderAccess.hpp"
#include "runtime/os.hpp"
#include "runtime/safepoint.hpp"
#include "runtime/thread.inline.hpp"
#include "runtime/vmThread.hpp"
#include "utilities/globalDefinitions.hpp"
#include "utilities/preserveException.hpp"
#include "utilities/top.hpp"

// Wrapper for all entry points to the virtual machine.
// The HandleMarkCleaner is a faster version of HandleMark.
// It relies on the fact that there is a HandleMark further
// down the stack (in JavaCalls::call_helper), and just resets
// to the saved values in that HandleMark.

class HandleMarkCleaner: public StackObj {
 private:
  Thread* _thread;
 public:
  HandleMarkCleaner(Thread* thread) {
    _thread = thread;
    _thread->last_handle_mark()->push();
  }
  ~HandleMarkCleaner() {
    _thread->last_handle_mark()->pop_and_restore();
  }

 private:
  inline void* operator new(size_t size, void* ptr) throw() {
    return ptr;
  }
};

// InterfaceSupport provides functionality used by the VM_LEAF_BASE and
// VM_ENTRY_BASE macros. These macros are used to guard entry points into
// the VM and perform checks upon leave of the VM.


class InterfaceSupport: AllStatic {
# ifdef ASSERT
 public:
  static long _scavenge_alot_counter;
  static long _fullgc_alot_counter;
  static long _number_of_calls;
  static long _fullgc_alot_invocation;

  // tracing
  static void trace(const char* result_type, const char* header);

  // Helper methods used to implement +ScavengeALot and +FullGCALot
  static void check_gc_alot() { if (ScavengeALot || FullGCALot) gc_alot(); }
  static void gc_alot();

  static void walk_stack_from(vframe* start_vf);
  static void walk_stack();

# ifdef ENABLE_ZAP_DEAD_LOCALS
  static void zap_dead_locals_old();
# endif

  static void zombieAll();
  static void unlinkSymbols();
  static void deoptimizeAll();
  static void stress_derived_pointers();
  static void verify_stack();
  static void verify_last_frame();
# endif

 public:
  // OS dependent stuff
#ifdef TARGET_OS_FAMILY_linux
# include "interfaceSupport_linux.hpp"
#endif
#ifdef TARGET_OS_FAMILY_solaris
# include "interfaceSupport_solaris.hpp"
#endif
#ifdef TARGET_OS_FAMILY_windows
# include "interfaceSupport_windows.hpp"
#endif
#ifdef TARGET_OS_FAMILY_bsd
# include "interfaceSupport_bsd.hpp"
#endif

};


// Basic class for all thread transition classes.

class ThreadStateTransition : public StackObj {
 protected:
  JavaThread* _thread;
 public:
  ThreadStateTransition(JavaThread *thread) {
    _thread = thread;
    assert(thread != NULL && thread->is_Java_thread(), "must be Java thread");
  }

  // Change threadstate in a manner, so safepoint can detect changes.
  // Time-critical: called on exit from every runtime routine
  static inline void transition(JavaThread *thread, JavaThreadState from, JavaThreadState to) {
    assert(from != _thread_in_Java, "use transition_from_java");
    assert(from != _thread_in_native, "use transition_from_native");
    assert((from & 1) == 0 && (to & 1) == 0, "odd numbers are transitions states");
    assert(thread->thread_state() == from, "coming from wrong thread state");
    // Change to transition state (assumes total store ordering!  -Urs)
    thread->set_thread_state((JavaThreadState)(from + 1));

    // Make sure new state is seen by VM thread
    if (os::is_MP()) {
      if (UseMembar) {
        // Force a fence between the write above and read below
        OrderAccess::fence();
      } else {
        // store to serialize page so VM thread can do pseudo remote membar
        os::write_memory_serialize_page(thread);
      }
    }

    if (SafepointSynchronize::do_call_back()) {
      SafepointSynchronize::block(thread);
    }
    thread->set_thread_state(to);

    CHECK_UNHANDLED_OOPS_ONLY(thread->clear_unhandled_oops();)
  }

  // transition_and_fence must be used on any thread state transition
  // where there might not be a Java call stub on the stack, in
  // particular on Windows where the Structured Exception Handler is
  // set up in the call stub. os::write_memory_serialize_page() can
  // fault and we can't recover from it on Windows without a SEH in
  // place.
  static inline void transition_and_fence(JavaThread *thread, JavaThreadState from, JavaThreadState to) {
    assert(thread->thread_state() == from, "coming from wrong thread state");
    assert((from & 1) == 0 && (to & 1) == 0, "odd numbers are transitions states");
    // Change to transition state (assumes total store ordering!  -Urs)
    thread->set_thread_state((JavaThreadState)(from + 1));

    // Make sure new state is seen by VM thread
    if (os::is_MP()) {
      if (UseMembar) {
        // Force a fence between the write above and read below
        OrderAccess::fence();
      } else {
        // Must use this rather than serialization page in particular on Windows
        InterfaceSupport::serialize_memory(thread);
      }
    }

    if (SafepointSynchronize::do_call_back()) {
      SafepointSynchronize::block(thread);
    }
    thread->set_thread_state(to);

    CHECK_UNHANDLED_OOPS_ONLY(thread->clear_unhandled_oops();)
  }

  // Same as above, but assumes from = _thread_in_Java. This is simpler, since we
  // never block on entry to the VM. This will break the code, since e.g. preserve arguments
  // have not been setup.
  static inline void transition_from_java(JavaThread *thread, JavaThreadState to) {
    assert(thread->thread_state() == _thread_in_Java, "coming from wrong thread state");
    thread->set_thread_state(to);
  }

  static inline void transition_from_native(JavaThread *thread, JavaThreadState to) {
    assert((to & 1) == 0, "odd numbers are transitions states");
    assert(thread->thread_state() == _thread_in_native, "coming from wrong thread state");
    // Change to transition state (assumes total store ordering!  -Urs)
    thread->set_thread_state(_thread_in_native_trans);

    // Make sure new state is seen by GC thread
    if (os::is_MP()) {
      if (UseMembar) {
        // Force a fence between the write above and read below
        OrderAccess::fence();
      } else {
        // Must use this rather than serialization page in particular on Windows
        InterfaceSupport::serialize_memory(thread);
      }
    }

    // We never install asynchronous exceptions when coming (back) in
    // to the runtime from native code because the runtime is not set
    // up to handle exceptions floating around at arbitrary points.
    if (SafepointSynchronize::do_call_back() || thread->is_suspend_after_native()) {
      JavaThread::check_safepoint_and_suspend_for_native_trans(thread);

      // Clear unhandled oops anywhere where we could block, even if we don't.
      CHECK_UNHANDLED_OOPS_ONLY(thread->clear_unhandled_oops();)
    }

    thread->set_thread_state(to);
  }
 protected:
   void trans(JavaThreadState from, JavaThreadState to)  { transition(_thread, from, to); }
   void trans_from_java(JavaThreadState to)              { transition_from_java(_thread, to); }
   void trans_from_native(JavaThreadState to)            { transition_from_native(_thread, to); }
   void trans_and_fence(JavaThreadState from, JavaThreadState to) { transition_and_fence(_thread, from, to); }
};


class ThreadInVMfromJava : public ThreadStateTransition {
 public:
  ThreadInVMfromJava(JavaThread* thread) : ThreadStateTransition(thread) {
    trans_from_java(_thread_in_vm);
  }
  ~ThreadInVMfromJava()  {
    trans(_thread_in_vm, _thread_in_Java);
    // Check for pending. async. exceptions or suspends.
    if (_thread->has_special_runtime_exit_condition()) _thread->handle_special_runtime_exit_condition();
  }
};


class ThreadInVMfromUnknown {
 private:
  JavaThread* _thread;
 public:
  ThreadInVMfromUnknown() : _thread(NULL) {
    Thread* t = Thread::current();
    if (t->is_Java_thread()) {
      JavaThread* t2 = (JavaThread*) t;
      if (t2->thread_state() == _thread_in_native) {
        _thread = t2;
        ThreadStateTransition::transition_from_native(t2, _thread_in_vm);
        // Used to have a HandleMarkCleaner but that is dangerous as
        // it could free a handle in our (indirect, nested) caller.
        // We expect any handles will be short lived and figure we
        // don't need an actual HandleMark.
      }
    }
  }
  ~ThreadInVMfromUnknown()  {
    if (_thread) {
      ThreadStateTransition::transition_and_fence(_thread, _thread_in_vm, _thread_in_native);
    }
  }
};


class ThreadInVMfromNative : public ThreadStateTransition {
 public:
  ThreadInVMfromNative(JavaThread* thread) : ThreadStateTransition(thread) {
    trans_from_native(_thread_in_vm);
  }
  ~ThreadInVMfromNative() {
    trans_and_fence(_thread_in_vm, _thread_in_native);
  }
};


class ThreadToNativeFromVM : public ThreadStateTransition {
 public:
  ThreadToNativeFromVM(JavaThread *thread) : ThreadStateTransition(thread) {
    // We are leaving the VM at this point and going directly to native code.
    // Block, if we are in the middle of a safepoint synchronization.
    assert(!thread->owns_locks(), "must release all locks when leaving VM");
    thread->frame_anchor()->make_walkable(thread);
    trans_and_fence(_thread_in_vm, _thread_in_native);
    // Check for pending. async. exceptions or suspends.
    if (_thread->has_special_runtime_exit_condition()) _thread->handle_special_runtime_exit_condition(false);
  }

  ~ThreadToNativeFromVM() {
    trans_from_native(_thread_in_vm);
    // We don't need to clear_walkable because it will happen automagically when we return to java
  }
};


class ThreadBlockInVM : public ThreadStateTransition {
 public:
  ThreadBlockInVM(JavaThread *thread)
  : ThreadStateTransition(thread) {
    // Once we are blocked vm expects stack to be walkable
    thread->frame_anchor()->make_walkable(thread);
    trans_and_fence(_thread_in_vm, _thread_blocked);
  }
  ~ThreadBlockInVM() {
    trans_and_fence(_thread_blocked, _thread_in_vm);
    // We don't need to clear_walkable because it will happen automagically when we return to java
  }
};


// This special transition class is only used to prevent asynchronous exceptions
// from being installed on vm exit in situations where we can't tolerate them.
// See bugs: 4324348, 4854693, 4998314, 5040492, 5050705.
class ThreadInVMfromJavaNoAsyncException : public ThreadStateTransition {
 public:
  ThreadInVMfromJavaNoAsyncException(JavaThread* thread) : ThreadStateTransition(thread) {
    trans_from_java(_thread_in_vm);
  }
  ~ThreadInVMfromJavaNoAsyncException()  {
    trans(_thread_in_vm, _thread_in_Java);
    // NOTE: We do not check for pending. async. exceptions.
    // If we did and moved the pending async exception over into the
    // pending exception field, we would need to deopt (currently C2
    // only). However, to do so would require that we transition back
    // to the _thread_in_vm state. Instead we postpone the handling of
    // the async exception.

    // Check for pending. suspends only.
    if (_thread->has_special_runtime_exit_condition())
      _thread->handle_special_runtime_exit_condition(false);
  }
};

// Debug class instantiated in JRT_ENTRY and ITR_ENTRY macro.
// Can be used to verify properties on enter/exit of the VM.

#ifdef ASSERT
class VMEntryWrapper {
 public:
  VMEntryWrapper() {
    if (VerifyLastFrame) {
      InterfaceSupport::verify_last_frame();
    }
  }

  ~VMEntryWrapper() {
    InterfaceSupport::check_gc_alot();
    if (WalkStackALot) {
      InterfaceSupport::walk_stack();
    }
#ifdef ENABLE_ZAP_DEAD_LOCALS
    if (ZapDeadLocalsOld) {
      InterfaceSupport::zap_dead_locals_old();
    }
#endif
#ifdef COMPILER2
    // This option is not used by Compiler 1
    if (StressDerivedPointers) {
      InterfaceSupport::stress_derived_pointers();
    }
#endif
    if (DeoptimizeALot || DeoptimizeRandom) {
      InterfaceSupport::deoptimizeAll();
    }
    if (ZombieALot) {
      InterfaceSupport::zombieAll();
    }
    if (UnlinkSymbolsALot) {
      InterfaceSupport::unlinkSymbols();
    }
    // do verification AFTER potential deoptimization
    if (VerifyStack) {
      InterfaceSupport::verify_stack();
    }

  }
};


class VMNativeEntryWrapper {
 public:
  VMNativeEntryWrapper() {
    if (GCALotAtAllSafepoints) InterfaceSupport::check_gc_alot();
  }

  ~VMNativeEntryWrapper() {
    if (GCALotAtAllSafepoints) InterfaceSupport::check_gc_alot();
  }
};

#endif


// VM-internal runtime interface support

#ifdef ASSERT

class RuntimeHistogramElement : public HistogramElement {
  public:
   RuntimeHistogramElement(const char* name);
};

#define TRACE_CALL(result_type, header)                            \
  InterfaceSupport::_number_of_calls++;                            \
  if (TraceRuntimeCalls)                                           \
    InterfaceSupport::trace(#result_type, #header);                \
  if (CountRuntimeCalls) {                                         \
    static RuntimeHistogramElement* e = new RuntimeHistogramElement(#header); \
    if (e != NULL) e->increment_count();                           \
  }
#else
#define TRACE_CALL(result_type, header)                            \
  /* do nothing */
#endif


// LEAF routines do not lock, GC or throw exceptions

#define VM_LEAF_BASE(result_type, header)                            \
  TRACE_CALL(result_type, header)                                    \
  debug_only(NoHandleMark __hm;)                                     \
  os::verify_stack_alignment();                                      \
  /* begin of body */


// ENTRY routines may lock, GC and throw exceptions

#define VM_ENTRY_BASE(result_type, header, thread)                   \
  TRACE_CALL(result_type, header)                                    \
  HandleMarkCleaner __hm(thread);                                    \
  Thread* THREAD = thread;                                           \
  os::verify_stack_alignment();                                      \
  /* begin of body */


// QUICK_ENTRY routines behave like ENTRY but without a handle mark

#define VM_QUICK_ENTRY_BASE(result_type, header, thread)             \
  TRACE_CALL(result_type, header)                                    \
  debug_only(NoHandleMark __hm;)                                     \
  Thread* THREAD = thread;                                           \
  os::verify_stack_alignment();                                      \
  /* begin of body */


// Definitions for IRT (Interpreter Runtime)
// (thread is an argument passed in to all these routines)

#define IRT_ENTRY(result_type, header)                               \
  result_type header {                                               \
    ThreadInVMfromJava __tiv(thread);                                \
    VM_ENTRY_BASE(result_type, header, thread)                       \
    debug_only(VMEntryWrapper __vew;)


#define IRT_LEAF(result_type, header)                                \
  result_type header {                                               \
    VM_LEAF_BASE(result_type, header)                                \
    debug_only(No_Safepoint_Verifier __nspv(true);)


#define IRT_ENTRY_NO_ASYNC(result_type, header)                      \
  result_type header {                                               \
    ThreadInVMfromJavaNoAsyncException __tiv(thread);                \
    VM_ENTRY_BASE(result_type, header, thread)                       \
    debug_only(VMEntryWrapper __vew;)

#define IRT_END }


// Definitions for JRT (Java (Compiler/Shared) Runtime)

#define JRT_ENTRY(result_type, header)                               \
  result_type header {                                               \
    ThreadInVMfromJava __tiv(thread);                                \
    VM_ENTRY_BASE(result_type, header, thread)                       \
    debug_only(VMEntryWrapper __vew;)


#define JRT_LEAF(result_type, header)                                \
  result_type header {                                               \
  VM_LEAF_BASE(result_type, header)                                  \
  debug_only(JRT_Leaf_Verifier __jlv;)


#define JRT_ENTRY_NO_ASYNC(result_type, header)                      \
  result_type header {                                               \
    ThreadInVMfromJavaNoAsyncException __tiv(thread);                \
    VM_ENTRY_BASE(result_type, header, thread)                       \
    debug_only(VMEntryWrapper __vew;)

// Same as JRT Entry but allows for return value after the safepoint
// to get back into Java from the VM
#define JRT_BLOCK_ENTRY(result_type, header)                         \
  result_type header {                                               \
    TRACE_CALL(result_type, header)                                  \
    HandleMarkCleaner __hm(thread);

#define JRT_BLOCK                                                    \
    {                                                                \
    ThreadInVMfromJava __tiv(thread);                                \
    Thread* THREAD = thread;                                         \
    debug_only(VMEntryWrapper __vew;)

#define JRT_BLOCK_END }

#define JRT_END }

// Definitions for JNI

#define JNI_ENTRY(result_type, header)                               \
    JNI_ENTRY_NO_PRESERVE(result_type, header)                       \
    WeakPreserveExceptionMark __wem(thread);

#define JNI_ENTRY_NO_PRESERVE(result_type, header)             \
extern "C" {                                                         \
  result_type JNICALL header {                                \
    JavaThread* thread=JavaThread::thread_from_jni_environment(env); \
    assert( !VerifyJNIEnvThread || (thread == Thread::current()), "JNIEnv is only valid in same thread"); \
    ThreadInVMfromNative __tiv(thread);                              \
    debug_only(VMNativeEntryWrapper __vew;)                          \
    VM_ENTRY_BASE(result_type, header, thread)


// Ensure that the VMNativeEntryWrapper constructor, which can cause
// a GC, is called outside the NoHandleMark (set via VM_QUICK_ENTRY_BASE).
#define JNI_QUICK_ENTRY(result_type, header)                         \
extern "C" {                                                         \
  result_type JNICALL header {                                \
    JavaThread* thread=JavaThread::thread_from_jni_environment(env); \
    assert( !VerifyJNIEnvThread || (thread == Thread::current()), "JNIEnv is only valid in same thread"); \
    ThreadInVMfromNative __tiv(thread);                              \
    debug_only(VMNativeEntryWrapper __vew;)                          \
    VM_QUICK_ENTRY_BASE(result_type, header, thread)


#define JNI_LEAF(result_type, header)                                \
extern "C" {                                                         \
  result_type JNICALL header {                                \
    JavaThread* thread=JavaThread::thread_from_jni_environment(env); \
    assert( !VerifyJNIEnvThread || (thread == Thread::current()), "JNIEnv is only valid in same thread"); \
    VM_LEAF_BASE(result_type, header)


// Close the routine and the extern "C"
#define JNI_END } }



// Definitions for JVM

#define JVM_ENTRY(result_type, header)                               \
extern "C" {                                                         \
  result_type JNICALL header {                                       \
    JavaThread* thread=JavaThread::thread_from_jni_environment(env); \
    ThreadInVMfromNative __tiv(thread);                              \
    debug_only(VMNativeEntryWrapper __vew;)                          \
    VM_ENTRY_BASE(result_type, header, thread)


#define JVM_ENTRY_NO_ENV(result_type, header)                        \
extern "C" {                                                         \
  result_type JNICALL header {                                       \
    JavaThread* thread = (JavaThread*)ThreadLocalStorage::thread();  \
    ThreadInVMfromNative __tiv(thread);                              \
    debug_only(VMNativeEntryWrapper __vew;)                          \
    VM_ENTRY_BASE(result_type, header, thread)


#define JVM_QUICK_ENTRY(result_type, header)                         \
extern "C" {                                                         \
  result_type JNICALL header {                                       \
    JavaThread* thread=JavaThread::thread_from_jni_environment(env); \
    ThreadInVMfromNative __tiv(thread);                              \
    debug_only(VMNativeEntryWrapper __vew;)                          \
    VM_QUICK_ENTRY_BASE(result_type, header, thread)


#define JVM_LEAF(result_type, header)                                \
extern "C" {                                                         \
  result_type JNICALL header {                                       \
    VM_Exit::block_if_vm_exited();                                   \
    VM_LEAF_BASE(result_type, header)


#define JVM_END } }

#endif // SHARE_VM_RUNTIME_INTERFACESUPPORT_HPP