blob: 944c8bd0dd6f44babc66b3f72a12e1dc1b0c9d3a [file] [log] [blame]
/*
* Copyright (C) 2011 The Android Open Source Project
*
* Licensed 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
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
#ifndef ART_RUNTIME_RUNTIME_H_
#define ART_RUNTIME_RUNTIME_H_
#include <jni.h>
#include <stdio.h>
#include <iosfwd>
#include <set>
#include <string>
#include <utility>
#include <vector>
#include "arch/instruction_set.h"
#include "base/allocator.h"
#include "base/macros.h"
#include "compiler_callbacks.h"
#include "gc_root.h"
#include "instrumentation.h"
#include "jobject_comparator.h"
#include "object_callbacks.h"
#include "offsets.h"
#include "profiler_options.h"
#include "quick/quick_method_frame_info.h"
#include "runtime_stats.h"
#include "safe_map.h"
namespace art {
namespace gc {
class Heap;
namespace collector {
class GarbageCollector;
} // namespace collector
} // namespace gc
namespace mirror {
class ArtMethod;
class ClassLoader;
class Array;
template<class T> class ObjectArray;
template<class T> class PrimitiveArray;
typedef PrimitiveArray<int8_t> ByteArray;
class String;
class Throwable;
} // namespace mirror
namespace verifier {
class MethodVerifier;
} // namespace verifier
class ClassLinker;
class Closure;
class DexFile;
class InternTable;
class JavaVMExt;
class MonitorList;
class MonitorPool;
class NullPointerHandler;
class SignalCatcher;
class StackOverflowHandler;
class SuspensionHandler;
class ThreadList;
class Trace;
class Transaction;
typedef std::vector<std::pair<std::string, const void*>> RuntimeOptions;
// Not all combinations of flags are valid. You may not visit all roots as well as the new roots
// (no logical reason to do this). You also may not start logging new roots and stop logging new
// roots (also no logical reason to do this).
enum VisitRootFlags : uint8_t {
kVisitRootFlagAllRoots = 0x1,
kVisitRootFlagNewRoots = 0x2,
kVisitRootFlagStartLoggingNewRoots = 0x4,
kVisitRootFlagStopLoggingNewRoots = 0x8,
kVisitRootFlagClearRootLog = 0x10,
};
class Runtime {
public:
// Creates and initializes a new runtime.
static bool Create(const RuntimeOptions& options, bool ignore_unrecognized)
SHARED_TRYLOCK_FUNCTION(true, Locks::mutator_lock_);
bool IsCompiler() const {
return compiler_callbacks_ != nullptr;
}
bool CanRelocate() const {
return !IsCompiler() || compiler_callbacks_->IsRelocationPossible();
}
bool ShouldRelocate() const {
return must_relocate_ && CanRelocate();
}
bool MustRelocateIfPossible() const {
return must_relocate_;
}
bool IsDex2OatEnabled() const {
return dex2oat_enabled_ && IsImageDex2OatEnabled();
}
bool IsImageDex2OatEnabled() const {
return image_dex2oat_enabled_;
}
CompilerCallbacks* GetCompilerCallbacks() {
return compiler_callbacks_;
}
bool IsZygote() const {
return is_zygote_;
}
bool IsExplicitGcDisabled() const {
return is_explicit_gc_disabled_;
}
std::string GetCompilerExecutable() const;
std::string GetPatchoatExecutable() const;
const std::vector<std::string>& GetCompilerOptions() const {
return compiler_options_;
}
void AddCompilerOption(std::string option) {
compiler_options_.push_back(option);
}
const std::vector<std::string>& GetImageCompilerOptions() const {
return image_compiler_options_;
}
const std::string& GetImageLocation() const {
return image_location_;
}
const ProfilerOptions& GetProfilerOptions() const {
return profiler_options_;
}
// Starts a runtime, which may cause threads to be started and code to run.
bool Start() UNLOCK_FUNCTION(Locks::mutator_lock_);
bool IsShuttingDown(Thread* self);
bool IsShuttingDownLocked() const EXCLUSIVE_LOCKS_REQUIRED(Locks::runtime_shutdown_lock_) {
return shutting_down_;
}
size_t NumberOfThreadsBeingBorn() const EXCLUSIVE_LOCKS_REQUIRED(Locks::runtime_shutdown_lock_) {
return threads_being_born_;
}
void StartThreadBirth() EXCLUSIVE_LOCKS_REQUIRED(Locks::runtime_shutdown_lock_) {
threads_being_born_++;
}
void EndThreadBirth() EXCLUSIVE_LOCKS_REQUIRED(Locks::runtime_shutdown_lock_);
bool IsStarted() const {
return started_;
}
bool IsFinishedStarting() const {
return finished_starting_;
}
static Runtime* Current() {
return instance_;
}
// Aborts semi-cleanly. Used in the implementation of LOG(FATAL), which most
// callers should prefer.
NO_RETURN static void Abort() LOCKS_EXCLUDED(Locks::abort_lock_);
// Returns the "main" ThreadGroup, used when attaching user threads.
jobject GetMainThreadGroup() const;
// Returns the "system" ThreadGroup, used when attaching our internal threads.
jobject GetSystemThreadGroup() const;
// Returns the system ClassLoader which represents the CLASSPATH.
jobject GetSystemClassLoader() const;
// Attaches the calling native thread to the runtime.
bool AttachCurrentThread(const char* thread_name, bool as_daemon, jobject thread_group,
bool create_peer);
void CallExitHook(jint status);
// Detaches the current native thread from the runtime.
void DetachCurrentThread() LOCKS_EXCLUDED(Locks::mutator_lock_);
void DumpForSigQuit(std::ostream& os);
void DumpLockHolders(std::ostream& os);
~Runtime();
const std::string& GetBootClassPathString() const {
return boot_class_path_string_;
}
const std::string& GetClassPathString() const {
return class_path_string_;
}
ClassLinker* GetClassLinker() const {
return class_linker_;
}
size_t GetDefaultStackSize() const {
return default_stack_size_;
}
gc::Heap* GetHeap() const {
return heap_;
}
InternTable* GetInternTable() const {
DCHECK(intern_table_ != NULL);
return intern_table_;
}
JavaVMExt* GetJavaVM() const {
return java_vm_;
}
size_t GetMaxSpinsBeforeThinkLockInflation() const {
return max_spins_before_thin_lock_inflation_;
}
MonitorList* GetMonitorList() const {
return monitor_list_;
}
MonitorPool* GetMonitorPool() const {
return monitor_pool_;
}
// Is the given object the special object used to mark a cleared JNI weak global?
bool IsClearedJniWeakGlobal(mirror::Object* obj) SHARED_LOCKS_REQUIRED(Locks::mutator_lock_);
// Get the special object used to mark a cleared JNI weak global.
mirror::Object* GetClearedJniWeakGlobal() SHARED_LOCKS_REQUIRED(Locks::mutator_lock_);
mirror::Throwable* GetPreAllocatedOutOfMemoryError() SHARED_LOCKS_REQUIRED(Locks::mutator_lock_);
mirror::Throwable* GetPreAllocatedNoClassDefFoundError()
SHARED_LOCKS_REQUIRED(Locks::mutator_lock_);
const std::vector<std::string>& GetProperties() const {
return properties_;
}
ThreadList* GetThreadList() const {
return thread_list_;
}
static const char* GetVersion() {
return "2.1.0";
}
void DisallowNewSystemWeaks() SHARED_LOCKS_REQUIRED(Locks::mutator_lock_);
void AllowNewSystemWeaks() SHARED_LOCKS_REQUIRED(Locks::mutator_lock_);
void EnsureNewSystemWeaksDisallowed() SHARED_LOCKS_REQUIRED(Locks::mutator_lock_);
// Visit all the roots. If only_dirty is true then non-dirty roots won't be visited. If
// clean_dirty is true then dirty roots will be marked as non-dirty after visiting.
void VisitRoots(RootCallback* visitor, void* arg, VisitRootFlags flags = kVisitRootFlagAllRoots)
SHARED_LOCKS_REQUIRED(Locks::mutator_lock_);
// Visit all of the roots we can do safely do concurrently.
void VisitConcurrentRoots(RootCallback* visitor, void* arg,
VisitRootFlags flags = kVisitRootFlagAllRoots)
SHARED_LOCKS_REQUIRED(Locks::mutator_lock_);
// Visit all of the non thread roots, we can do this with mutators unpaused.
void VisitNonThreadRoots(RootCallback* visitor, void* arg)
SHARED_LOCKS_REQUIRED(Locks::mutator_lock_);
void VisitTransactionRoots(RootCallback* visitor, void* arg)
SHARED_LOCKS_REQUIRED(Locks::mutator_lock_);
// Visit all of the thread roots.
void VisitThreadRoots(RootCallback* visitor, void* arg) SHARED_LOCKS_REQUIRED(Locks::mutator_lock_);
// Flip thread roots from from-space refs to to-space refs.
size_t FlipThreadRoots(Closure* thread_flip_visitor, Closure* flip_callback,
gc::collector::GarbageCollector* collector)
LOCKS_EXCLUDED(Locks::mutator_lock_);
// Visit all other roots which must be done with mutators suspended.
void VisitNonConcurrentRoots(RootCallback* visitor, void* arg)
SHARED_LOCKS_REQUIRED(Locks::mutator_lock_);
// Sweep system weaks, the system weak is deleted if the visitor return nullptr. Otherwise, the
// system weak is updated to be the visitor's returned value.
void SweepSystemWeaks(IsMarkedCallback* visitor, void* arg)
SHARED_LOCKS_REQUIRED(Locks::mutator_lock_);
// Constant roots are the roots which never change after the runtime is initialized, they only
// need to be visited once per GC cycle.
void VisitConstantRoots(RootCallback* callback, void* arg)
SHARED_LOCKS_REQUIRED(Locks::mutator_lock_);
// Returns a special method that calls into a trampoline for runtime method resolution
mirror::ArtMethod* GetResolutionMethod() SHARED_LOCKS_REQUIRED(Locks::mutator_lock_);
bool HasResolutionMethod() const {
return !resolution_method_.IsNull();
}
void SetResolutionMethod(mirror::ArtMethod* method) {
resolution_method_ = GcRoot<mirror::ArtMethod>(method);
}
mirror::ArtMethod* CreateResolutionMethod() SHARED_LOCKS_REQUIRED(Locks::mutator_lock_);
// Returns a special method that calls into a trampoline for runtime imt conflicts.
mirror::ArtMethod* GetImtConflictMethod() SHARED_LOCKS_REQUIRED(Locks::mutator_lock_);
mirror::ArtMethod* GetImtUnimplementedMethod() SHARED_LOCKS_REQUIRED(Locks::mutator_lock_);
bool HasImtConflictMethod() const {
return !imt_conflict_method_.IsNull();
}
void SetImtConflictMethod(mirror::ArtMethod* method) {
imt_conflict_method_ = GcRoot<mirror::ArtMethod>(method);
}
void SetImtUnimplementedMethod(mirror::ArtMethod* method) {
imt_unimplemented_method_ = GcRoot<mirror::ArtMethod>(method);
}
mirror::ArtMethod* CreateImtConflictMethod() SHARED_LOCKS_REQUIRED(Locks::mutator_lock_);
// Returns an imt with every entry set to conflict, used as default imt for all classes.
mirror::ObjectArray<mirror::ArtMethod>* GetDefaultImt()
SHARED_LOCKS_REQUIRED(Locks::mutator_lock_);
bool HasDefaultImt() const {
return !default_imt_.IsNull();
}
void SetDefaultImt(mirror::ObjectArray<mirror::ArtMethod>* imt) {
default_imt_ = GcRoot<mirror::ObjectArray<mirror::ArtMethod>>(imt);
}
mirror::ObjectArray<mirror::ArtMethod>* CreateDefaultImt(ClassLinker* cl)
SHARED_LOCKS_REQUIRED(Locks::mutator_lock_);
// Returns a special method that describes all callee saves being spilled to the stack.
enum CalleeSaveType {
kSaveAll,
kRefsOnly,
kRefsAndArgs,
kLastCalleeSaveType // Value used for iteration
};
bool HasCalleeSaveMethod(CalleeSaveType type) const {
return !callee_save_methods_[type].IsNull();
}
mirror::ArtMethod* GetCalleeSaveMethod(CalleeSaveType type)
SHARED_LOCKS_REQUIRED(Locks::mutator_lock_);
mirror::ArtMethod* GetCalleeSaveMethodUnchecked(CalleeSaveType type)
SHARED_LOCKS_REQUIRED(Locks::mutator_lock_);
QuickMethodFrameInfo GetCalleeSaveMethodFrameInfo(CalleeSaveType type) const {
return callee_save_method_frame_infos_[type];
}
QuickMethodFrameInfo GetRuntimeMethodFrameInfo(mirror::ArtMethod* method)
SHARED_LOCKS_REQUIRED(Locks::mutator_lock_);
static size_t GetCalleeSaveMethodOffset(CalleeSaveType type) {
return OFFSETOF_MEMBER(Runtime, callee_save_methods_[type]);
}
InstructionSet GetInstructionSet() const {
return instruction_set_;
}
void SetInstructionSet(InstructionSet instruction_set);
void SetCalleeSaveMethod(mirror::ArtMethod* method, CalleeSaveType type);
mirror::ArtMethod* CreateCalleeSaveMethod() SHARED_LOCKS_REQUIRED(Locks::mutator_lock_);
int32_t GetStat(int kind);
RuntimeStats* GetStats() {
return &stats_;
}
bool HasStatsEnabled() const {
return stats_enabled_;
}
void ResetStats(int kinds);
void SetStatsEnabled(bool new_state) LOCKS_EXCLUDED(Locks::instrument_entrypoints_lock_,
Locks::mutator_lock_);
enum class NativeBridgeAction { // private
kUnload,
kInitialize
};
void PreZygoteFork();
bool InitZygote();
void DidForkFromZygote(JNIEnv* env, NativeBridgeAction action, const char* isa);
const instrumentation::Instrumentation* GetInstrumentation() const {
return &instrumentation_;
}
instrumentation::Instrumentation* GetInstrumentation() {
return &instrumentation_;
}
bool UseCompileTimeClassPath() const {
return use_compile_time_class_path_;
}
void AddMethodVerifier(verifier::MethodVerifier* verifier) LOCKS_EXCLUDED(method_verifier_lock_);
void RemoveMethodVerifier(verifier::MethodVerifier* verifier)
LOCKS_EXCLUDED(method_verifier_lock_);
const std::vector<const DexFile*>& GetCompileTimeClassPath(jobject class_loader);
// The caller is responsible for ensuring the class_path DexFiles remain
// valid as long as the Runtime object remains valid.
void SetCompileTimeClassPath(jobject class_loader, std::vector<const DexFile*>& class_path);
void StartProfiler(const char* profile_output_filename);
void UpdateProfilerState(int state);
// Transaction support.
bool IsActiveTransaction() const {
return preinitialization_transaction_ != nullptr;
}
void EnterTransactionMode(Transaction* transaction);
void ExitTransactionMode();
bool IsTransactionAborted() const;
void AbortTransactionAndThrowInternalError(Thread* self, const std::string& abort_message)
SHARED_LOCKS_REQUIRED(Locks::mutator_lock_);
void ThrowInternalErrorForAbortedTransaction(Thread* self)
SHARED_LOCKS_REQUIRED(Locks::mutator_lock_);
void RecordWriteFieldBoolean(mirror::Object* obj, MemberOffset field_offset, uint8_t value,
bool is_volatile) const;
void RecordWriteFieldByte(mirror::Object* obj, MemberOffset field_offset, int8_t value,
bool is_volatile) const;
void RecordWriteFieldChar(mirror::Object* obj, MemberOffset field_offset, uint16_t value,
bool is_volatile) const;
void RecordWriteFieldShort(mirror::Object* obj, MemberOffset field_offset, int16_t value,
bool is_volatile) const;
void RecordWriteField32(mirror::Object* obj, MemberOffset field_offset, uint32_t value,
bool is_volatile) const;
void RecordWriteField64(mirror::Object* obj, MemberOffset field_offset, uint64_t value,
bool is_volatile) const;
void RecordWriteFieldReference(mirror::Object* obj, MemberOffset field_offset,
mirror::Object* value, bool is_volatile) const;
void RecordWriteArray(mirror::Array* array, size_t index, uint64_t value) const
SHARED_LOCKS_REQUIRED(Locks::mutator_lock_);
void RecordStrongStringInsertion(mirror::String* s) const
EXCLUSIVE_LOCKS_REQUIRED(Locks::intern_table_lock_);
void RecordWeakStringInsertion(mirror::String* s) const
EXCLUSIVE_LOCKS_REQUIRED(Locks::intern_table_lock_);
void RecordStrongStringRemoval(mirror::String* s) const
EXCLUSIVE_LOCKS_REQUIRED(Locks::intern_table_lock_);
void RecordWeakStringRemoval(mirror::String* s) const
EXCLUSIVE_LOCKS_REQUIRED(Locks::intern_table_lock_);
void SetFaultMessage(const std::string& message);
// Only read by the signal handler, NO_THREAD_SAFETY_ANALYSIS to prevent lock order violations
// with the unexpected_signal_lock_.
const std::string& GetFaultMessage() NO_THREAD_SAFETY_ANALYSIS {
return fault_message_;
}
void AddCurrentRuntimeFeaturesAsDex2OatArguments(std::vector<std::string>* arg_vector) const;
bool ExplicitStackOverflowChecks() const {
return !implicit_so_checks_;
}
bool IsVerificationEnabled() const {
return verify_;
}
bool IsDexFileFallbackEnabled() const {
return allow_dex_file_fallback_;
}
bool RunningOnValgrind() const {
return running_on_valgrind_;
}
void SetTargetSdkVersion(int32_t version) {
target_sdk_version_ = version;
}
int32_t GetTargetSdkVersion() const {
return target_sdk_version_;
}
uint32_t GetZygoteMaxFailedBoots() const {
return zygote_max_failed_boots_;
}
private:
static void InitPlatformSignalHandlers();
Runtime();
void BlockSignals();
bool Init(const RuntimeOptions& options, bool ignore_unrecognized)
SHARED_TRYLOCK_FUNCTION(true, Locks::mutator_lock_);
void InitNativeMethods() LOCKS_EXCLUDED(Locks::mutator_lock_);
void InitThreadGroups(Thread* self);
void RegisterRuntimeNativeMethods(JNIEnv* env);
void StartDaemonThreads();
void StartSignalCatcher();
// A pointer to the active runtime or NULL.
static Runtime* instance_;
// NOTE: these must match the gc::ProcessState values as they come directly from the framework.
static constexpr int kProfileForground = 0;
static constexpr int kProfileBackgrouud = 1;
GcRoot<mirror::ArtMethod> callee_save_methods_[kLastCalleeSaveType];
GcRoot<mirror::Throwable> pre_allocated_OutOfMemoryError_;
GcRoot<mirror::Throwable> pre_allocated_NoClassDefFoundError_;
GcRoot<mirror::ArtMethod> resolution_method_;
GcRoot<mirror::ArtMethod> imt_conflict_method_;
// Unresolved method has the same behavior as the conflict method, it is used by the class linker
// for differentiating between unfilled imt slots vs conflict slots in superclasses.
GcRoot<mirror::ArtMethod> imt_unimplemented_method_;
GcRoot<mirror::ObjectArray<mirror::ArtMethod>> default_imt_;
// Special sentinel object used to invalid conditions in JNI (cleared weak references) and
// JDWP (invalid references).
GcRoot<mirror::Object> sentinel_;
InstructionSet instruction_set_;
QuickMethodFrameInfo callee_save_method_frame_infos_[kLastCalleeSaveType];
CompilerCallbacks* compiler_callbacks_;
bool is_zygote_;
bool must_relocate_;
bool is_concurrent_gc_enabled_;
bool is_explicit_gc_disabled_;
bool dex2oat_enabled_;
bool image_dex2oat_enabled_;
std::string compiler_executable_;
std::string patchoat_executable_;
std::vector<std::string> compiler_options_;
std::vector<std::string> image_compiler_options_;
std::string image_location_;
std::string boot_class_path_string_;
std::string class_path_string_;
std::vector<std::string> properties_;
// The default stack size for managed threads created by the runtime.
size_t default_stack_size_;
gc::Heap* heap_;
// The number of spins that are done before thread suspension is used to forcibly inflate.
size_t max_spins_before_thin_lock_inflation_;
MonitorList* monitor_list_;
MonitorPool* monitor_pool_;
ThreadList* thread_list_;
InternTable* intern_table_;
ClassLinker* class_linker_;
SignalCatcher* signal_catcher_;
std::string stack_trace_file_;
JavaVMExt* java_vm_;
// Fault message, printed when we get a SIGSEGV.
Mutex fault_message_lock_ DEFAULT_MUTEX_ACQUIRED_AFTER;
std::string fault_message_ GUARDED_BY(fault_message_lock_);
// Method verifier set, used so that we can update their GC roots.
Mutex method_verifier_lock_ DEFAULT_MUTEX_ACQUIRED_AFTER;
std::set<verifier::MethodVerifier*> method_verifiers_;
// A non-zero value indicates that a thread has been created but not yet initialized. Guarded by
// the shutdown lock so that threads aren't born while we're shutting down.
size_t threads_being_born_ GUARDED_BY(Locks::runtime_shutdown_lock_);
// Waited upon until no threads are being born.
std::unique_ptr<ConditionVariable> shutdown_cond_ GUARDED_BY(Locks::runtime_shutdown_lock_);
// Set when runtime shutdown is past the point that new threads may attach.
bool shutting_down_ GUARDED_BY(Locks::runtime_shutdown_lock_);
// The runtime is starting to shutdown but is blocked waiting on shutdown_cond_.
bool shutting_down_started_ GUARDED_BY(Locks::runtime_shutdown_lock_);
bool started_;
// New flag added which tells us if the runtime has finished starting. If
// this flag is set then the Daemon threads are created and the class loader
// is created. This flag is needed for knowing if its safe to request CMS.
bool finished_starting_;
// Hooks supported by JNI_CreateJavaVM
jint (*vfprintf_)(FILE* stream, const char* format, va_list ap);
void (*exit_)(jint status);
void (*abort_)();
bool stats_enabled_;
RuntimeStats stats_;
const bool running_on_valgrind_;
std::string profile_output_filename_;
ProfilerOptions profiler_options_;
bool profiler_started_;
bool method_trace_;
std::string method_trace_file_;
size_t method_trace_file_size_;
instrumentation::Instrumentation instrumentation_;
typedef AllocationTrackingSafeMap<jobject, std::vector<const DexFile*>,
kAllocatorTagCompileTimeClassPath, JobjectComparator>
CompileTimeClassPaths;
CompileTimeClassPaths compile_time_class_paths_;
bool use_compile_time_class_path_;
jobject main_thread_group_;
jobject system_thread_group_;
// As returned by ClassLoader.getSystemClassLoader().
jobject system_class_loader_;
// If true, then we dump the GC cumulative timings on shutdown.
bool dump_gc_performance_on_shutdown_;
// Transaction used for pre-initializing classes at compilation time.
Transaction* preinitialization_transaction_;
// If false, verification is disabled. True by default.
bool verify_;
// If true, the runtime may use dex files directly with the interpreter if an oat file is not
// available/usable.
bool allow_dex_file_fallback_;
// Specifies target SDK version to allow workarounds for certain API levels.
int32_t target_sdk_version_;
// Implicit checks flags.
bool implicit_null_checks_; // NullPointer checks are implicit.
bool implicit_so_checks_; // StackOverflow checks are implicit.
bool implicit_suspend_checks_; // Thread suspension checks are implicit.
// Whether or not a native bridge has been loaded.
//
// The native bridge allows running native code compiled for a foreign ISA. The way it works is,
// if standard dlopen fails to load native library associated with native activity, it calls to
// the native bridge to load it and then gets the trampoline for the entry to native activity.
//
// The option 'native_bridge_library_filename' specifies the name of the native bridge.
// When non-empty the native bridge will be loaded from the given file. An empty value means
// that there's no native bridge.
bool is_native_bridge_loaded_;
// The maximum number of failed boots we allow before pruning the dalvik cache
// and trying again. This option is only inspected when we're running as a
// zygote.
uint32_t zygote_max_failed_boots_;
DISALLOW_COPY_AND_ASSIGN(Runtime);
};
std::ostream& operator<<(std::ostream& os, const Runtime::CalleeSaveType& rhs);
} // namespace art
#endif // ART_RUNTIME_RUNTIME_H_