openjdkjvmti/ti_thread.h - platform/art - Git at Google

 /* Copyright (C) 2017 The Android Open Source Project
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This file implements interfaces from the file jvmti.h. This implementation
  * is licensed under the same terms as the file jvmti.h.  The
  * copyright and license information for the file jvmti.h follows.
  *
  * Copyright (c) 2003, 2011, 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.  Oracle designates this
  * particular file as subject to the "Classpath" exception as provided
  * by Oracle in the LICENSE file that accompanied this code.
  *
  * 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 ART_OPENJDKJVMTI_TI_THREAD_H_
 #define ART_OPENJDKJVMTI_TI_THREAD_H_

 #include <unordered_map>

 #include "jni.h"
 #include "jvmti.h"

 #include "base/macros.h"
 #include "base/mutex.h"
 #include "thread.h"

 namespace art {
 class ArtField;
 class ScopedObjectAccessAlreadyRunnable;
 class Thread;
 class Closure;
 }  // namespace art

 namespace openjdkjvmti {

 class EventHandler;

 // The struct that we store in the art::Thread::custom_tls_ that maps the jvmtiEnvs to the data
 // stored with that thread. This is needed since different jvmtiEnvs are not supposed to share TLS
 // data but we only have a single slot in Thread objects to store data.
 struct JvmtiGlobalTLSData : public art::TLSData {
   std::unordered_map<jvmtiEnv*, const void*> data GUARDED_BY(art::Locks::thread_list_lock_);

   // The depth of the last frame where popping using PopFrame it is not allowed. It is set to
   // kNoDisallowedPopFrame if all frames can be popped. See b/117615146 for more information.
   static constexpr size_t kNoDisallowedPopFrame = -1;
   size_t disable_pop_frame_depth = kNoDisallowedPopFrame;
 };

 class ThreadUtil {
  public:
   static void Register(EventHandler* event_handler);
   static void Unregister();

   // To be called when it is safe to cache data. This means that we have at least entered the
   // RuntimePhase::kInit but we might or might not have already called VMInit event.
   static void CacheData();

   // Called just after we have sent the VMInit callback so that ThreadUtil can do final setup. This
   // ensures that there are no timing issues between the two callbacks.
   static void VMInitEventSent() REQUIRES_SHARED(art::Locks::mutator_lock_);

   // Handle a jvmtiEnv going away.
   static void RemoveEnvironment(jvmtiEnv* env);

   static jvmtiError GetAllThreads(jvmtiEnv* env, jint* threads_count_ptr, jthread** threads_ptr);

   static jvmtiError GetCurrentThread(jvmtiEnv* env, jthread* thread_ptr);

   static jvmtiError GetThreadInfo(jvmtiEnv* env, jthread thread, jvmtiThreadInfo* info_ptr);

   static jvmtiError GetThreadState(jvmtiEnv* env, jthread thread, jint* thread_state_ptr);

   static jvmtiError SetThreadLocalStorage(jvmtiEnv* env, jthread thread, const void* data);
   static jvmtiError GetThreadLocalStorage(jvmtiEnv* env, jthread thread, void** data_ptr);

   static jvmtiError RunAgentThread(jvmtiEnv* env,
                                    jthread thread,
                                    jvmtiStartFunction proc,
                                    const void* arg,
                                    jint priority);

   static jvmtiError SuspendThread(jvmtiEnv* env, jthread thread);
   static jvmtiError ResumeThread(jvmtiEnv* env, jthread thread);

   static jvmtiError SuspendThreadList(jvmtiEnv* env,
                                       jint request_count,
                                       const jthread* threads,
                                       jvmtiError* results);
   static jvmtiError ResumeThreadList(jvmtiEnv* env,
                                      jint request_count,
                                      const jthread* threads,
                                      jvmtiError* results);

   static jvmtiError StopThread(jvmtiEnv* env, jthread thr, jobject exception);
   static jvmtiError InterruptThread(jvmtiEnv* env, jthread thr);

   // Returns true if we decoded the thread and it is alive, false otherwise with an appropriate
   // error placed into 'err'. A thread is alive if it has had it's 'start' function called and has
   // (or at least could have) executed managed code and has not yet returned past it's first managed
   // frame. This means that the thread returned might have IsStillStarting() return true. Code that
   // does not consider that alive should check manually.
   static bool GetAliveNativeThread(jthread thread,
                                    const art::ScopedObjectAccessAlreadyRunnable& soa,
                                    /*out*/ art::Thread** thr,
                                    /*out*/ jvmtiError* err)
       REQUIRES_SHARED(art::Locks::mutator_lock_)
       REQUIRES(art::Locks::thread_list_lock_);

   // Returns true if we decoded the thread, false otherwise with an appropriate error placed into
   // 'err'
   static bool GetNativeThread(jthread thread,
                               const art::ScopedObjectAccessAlreadyRunnable& soa,
                               /*out*/ art::Thread** thr,
                               /*out*/ jvmtiError* err)
       REQUIRES_SHARED(art::Locks::mutator_lock_)
       REQUIRES(art::Locks::thread_list_lock_);

   // Go to sleep if this thread is suspended.
   static void SuspendCheck(art::Thread* self)
     REQUIRES(!art::Locks::mutator_lock_, !art::Locks::user_code_suspension_lock_);

   // Returns true if the thread would be suspended if it locks the mutator-lock or calls
   // SuspendCheck. This function is called with the user_code_suspension_lock already held.
   static bool WouldSuspendForUserCodeLocked(art::Thread* self)
     REQUIRES(art::Locks::user_code_suspension_lock_,
              !art::Locks::thread_suspend_count_lock_);

   // Returns true if this thread would go to sleep if it locks the mutator-lock or calls
   // SuspendCheck.
   static bool WouldSuspendForUserCode(art::Thread* self)
     REQUIRES(!art::Locks::user_code_suspension_lock_,
              !art::Locks::thread_suspend_count_lock_);

   static JvmtiGlobalTLSData* GetGlobalTLSData(art::Thread* thread)
       REQUIRES(art::Locks::thread_list_lock_);
   static JvmtiGlobalTLSData* GetOrCreateGlobalTLSData(art::Thread* thread)
       REQUIRES(art::Locks::thread_list_lock_);

  private:
   // We need to make sure only one thread tries to suspend threads at a time so we can get the
   // 'suspend-only-once' behavior the spec requires. Internally, ART considers suspension to be a
   // counted state, allowing a single thread to be suspended multiple times by different users. This
   // makes mapping into the JVMTI idea of thread suspension difficult. We have decided to split the
   // difference and ensure that JVMTI tries to treat suspension as the boolean flag as much as
   // possible with the suspend/resume methods but only do best effort. On the other hand
   // GetThreadState will be totally accurate as much as possible. This means that calling
   // ResumeThread on a thread that has state JVMTI_THREAD_STATE_SUSPENDED will not necessarily
   // cause the thread to wake up if the thread is suspended for the debugger or gc or something.
   static jvmtiError SuspendSelf(art::Thread* self)
       REQUIRES(!art::Locks::mutator_lock_, !art::Locks::user_code_suspension_lock_);
   static jvmtiError SuspendOther(art::Thread* self, jthread target_jthread)
       REQUIRES(!art::Locks::mutator_lock_, !art::Locks::user_code_suspension_lock_);

   static art::ArtField* context_class_loader_;
 };

 }  // namespace openjdkjvmti

 #endif  // ART_OPENJDKJVMTI_TI_THREAD_H_
	/* Copyright (C) 2017 The Android Open Source Project
	* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
	*
	* This file implements interfaces from the file jvmti.h. This implementation
	* is licensed under the same terms as the file jvmti.h. The
	* copyright and license information for the file jvmti.h follows.
	*
	* Copyright (c) 2003, 2011, 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. Oracle designates this
	* particular file as subject to the "Classpath" exception as provided
	* by Oracle in the LICENSE file that accompanied this code.
	*
	* 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 ART_OPENJDKJVMTI_TI_THREAD_H_
	#define ART_OPENJDKJVMTI_TI_THREAD_H_

	#include <unordered_map>

	#include "jni.h"
	#include "jvmti.h"

	#include "base/macros.h"
	#include "base/mutex.h"
	#include "thread.h"

	namespace art {
	class ArtField;
	class ScopedObjectAccessAlreadyRunnable;
	class Thread;
	class Closure;
	} // namespace art

	namespace openjdkjvmti {

	class EventHandler;

	// The struct that we store in the art::Thread::custom_tls_ that maps the jvmtiEnvs to the data
	// stored with that thread. This is needed since different jvmtiEnvs are not supposed to share TLS
	// data but we only have a single slot in Thread objects to store data.
	struct JvmtiGlobalTLSData : public art::TLSData {
	std::unordered_map<jvmtiEnv, const void> data GUARDED_BY(art::Locks::thread_list_lock_);

	// The depth of the last frame where popping using PopFrame it is not allowed. It is set to
	// kNoDisallowedPopFrame if all frames can be popped. See b/117615146 for more information.
	static constexpr size_t kNoDisallowedPopFrame = -1;
	size_t disable_pop_frame_depth = kNoDisallowedPopFrame;
	};

	class ThreadUtil {
	public:
	static void Register(EventHandler* event_handler);
	static void Unregister();

	// To be called when it is safe to cache data. This means that we have at least entered the
	// RuntimePhase::kInit but we might or might not have already called VMInit event.
	static void CacheData();

	// Called just after we have sent the VMInit callback so that ThreadUtil can do final setup. This
	// ensures that there are no timing issues between the two callbacks.
	static void VMInitEventSent() REQUIRES_SHARED(art::Locks::mutator_lock_);

	// Handle a jvmtiEnv going away.
	static void RemoveEnvironment(jvmtiEnv* env);

	static jvmtiError GetAllThreads(jvmtiEnv* env, jint* threads_count_ptr, jthread** threads_ptr);

	static jvmtiError GetCurrentThread(jvmtiEnv* env, jthread* thread_ptr);

	static jvmtiError GetThreadInfo(jvmtiEnv* env, jthread thread, jvmtiThreadInfo* info_ptr);

	static jvmtiError GetThreadState(jvmtiEnv* env, jthread thread, jint* thread_state_ptr);

	static jvmtiError SetThreadLocalStorage(jvmtiEnv* env, jthread thread, const void* data);
	static jvmtiError GetThreadLocalStorage(jvmtiEnv* env, jthread thread, void** data_ptr);

	static jvmtiError RunAgentThread(jvmtiEnv* env,
	jthread thread,
	jvmtiStartFunction proc,
	const void* arg,
	jint priority);

	static jvmtiError SuspendThread(jvmtiEnv* env, jthread thread);
	static jvmtiError ResumeThread(jvmtiEnv* env, jthread thread);

	static jvmtiError SuspendThreadList(jvmtiEnv* env,
	jint request_count,
	const jthread* threads,
	jvmtiError* results);
	static jvmtiError ResumeThreadList(jvmtiEnv* env,
	jint request_count,
	const jthread* threads,
	jvmtiError* results);

	static jvmtiError StopThread(jvmtiEnv* env, jthread thr, jobject exception);
	static jvmtiError InterruptThread(jvmtiEnv* env, jthread thr);

	// Returns true if we decoded the thread and it is alive, false otherwise with an appropriate
	// error placed into 'err'. A thread is alive if it has had it's 'start' function called and has
	// (or at least could have) executed managed code and has not yet returned past it's first managed
	// frame. This means that the thread returned might have IsStillStarting() return true. Code that
	// does not consider that alive should check manually.
	static bool GetAliveNativeThread(jthread thread,
	const art::ScopedObjectAccessAlreadyRunnable& soa,
	/out/ art::Thread** thr,
	/out/ jvmtiError* err)
	REQUIRES_SHARED(art::Locks::mutator_lock_)
	REQUIRES(art::Locks::thread_list_lock_);

	// Returns true if we decoded the thread, false otherwise with an appropriate error placed into
	// 'err'
	static bool GetNativeThread(jthread thread,
	const art::ScopedObjectAccessAlreadyRunnable& soa,
	/out/ art::Thread** thr,
	/out/ jvmtiError* err)
	REQUIRES_SHARED(art::Locks::mutator_lock_)
	REQUIRES(art::Locks::thread_list_lock_);

	// Go to sleep if this thread is suspended.
	static void SuspendCheck(art::Thread* self)
	REQUIRES(!art::Locks::mutator_lock_, !art::Locks::user_code_suspension_lock_);

	// Returns true if the thread would be suspended if it locks the mutator-lock or calls
	// SuspendCheck. This function is called with the user_code_suspension_lock already held.
	static bool WouldSuspendForUserCodeLocked(art::Thread* self)
	REQUIRES(art::Locks::user_code_suspension_lock_,
	!art::Locks::thread_suspend_count_lock_);

	// Returns true if this thread would go to sleep if it locks the mutator-lock or calls
	// SuspendCheck.
	static bool WouldSuspendForUserCode(art::Thread* self)
	REQUIRES(!art::Locks::user_code_suspension_lock_,
	!art::Locks::thread_suspend_count_lock_);

	static JvmtiGlobalTLSData* GetGlobalTLSData(art::Thread* thread)
	REQUIRES(art::Locks::thread_list_lock_);
	static JvmtiGlobalTLSData* GetOrCreateGlobalTLSData(art::Thread* thread)
	REQUIRES(art::Locks::thread_list_lock_);

	private:
	// We need to make sure only one thread tries to suspend threads at a time so we can get the
	// 'suspend-only-once' behavior the spec requires. Internally, ART considers suspension to be a
	// counted state, allowing a single thread to be suspended multiple times by different users. This
	// makes mapping into the JVMTI idea of thread suspension difficult. We have decided to split the
	// difference and ensure that JVMTI tries to treat suspension as the boolean flag as much as
	// possible with the suspend/resume methods but only do best effort. On the other hand
	// GetThreadState will be totally accurate as much as possible. This means that calling
	// ResumeThread on a thread that has state JVMTI_THREAD_STATE_SUSPENDED will not necessarily
	// cause the thread to wake up if the thread is suspended for the debugger or gc or something.
	static jvmtiError SuspendSelf(art::Thread* self)
	REQUIRES(!art::Locks::mutator_lock_, !art::Locks::user_code_suspension_lock_);
	static jvmtiError SuspendOther(art::Thread* self, jthread target_jthread)
	REQUIRES(!art::Locks::mutator_lock_, !art::Locks::user_code_suspension_lock_);

	static art::ArtField* context_class_loader_;
	};

	} // namespace openjdkjvmti

	#endif // ART_OPENJDKJVMTI_TI_THREAD_H_