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/*
* Copyright (c) 1998, 2022, 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_RUNTIME_SYNCHRONIZER_HPP
#define SHARE_RUNTIME_SYNCHRONIZER_HPP
#include "memory/padded.hpp"
#include "oops/markWord.hpp"
#include "runtime/basicLock.hpp"
#include "runtime/handles.hpp"
#include "utilities/resourceHash.hpp"
template <typename T> class GrowableArray;
class LogStream;
class ObjectMonitor;
class ThreadsList;
// Hash table of void* to a list of ObjectMonitor* owned by the JavaThread.
// The JavaThread's owner key is either a JavaThread* or a stack lock
// address in the JavaThread so we use "void*".
//
class ObjectMonitorsHashtable {
private:
static unsigned int ptr_hash(void* const& s1) {
// 2654435761 = 2^32 * Phi (golden ratio)
return (unsigned int)(((uint32_t)(uintptr_t)s1) * 2654435761u);
}
public:
class PtrList;
private:
// ResourceHashtable SIZE is specified at compile time so we
// use 1031 which is the first prime after 1024.
typedef ResourceHashtable<void*, PtrList*, 1031, AnyObj::C_HEAP, mtThread,
&ObjectMonitorsHashtable::ptr_hash> PtrTable;
PtrTable* _ptrs;
size_t _key_count;
size_t _om_count;
public:
// ResourceHashtable is passed to various functions and populated in
// different places so we allocate it using C_HEAP to make it immune
// from any ResourceMarks that happen to be in the code paths.
ObjectMonitorsHashtable() : _ptrs(new (mtThread) PtrTable), _key_count(0), _om_count(0) {}
~ObjectMonitorsHashtable();
void add_entry(void* key, ObjectMonitor* om);
void add_entry(void* key, PtrList* list) {
_ptrs->put(key, list);
_key_count++;
}
PtrList* get_entry(void* key) {
PtrList** listpp = _ptrs->get(key);
return (listpp == nullptr) ? nullptr : *listpp;
}
bool has_entry(void* key, ObjectMonitor* om);
size_t key_count() { return _key_count; }
size_t om_count() { return _om_count; }
};
class MonitorList {
friend class VMStructs;
private:
ObjectMonitor* volatile _head;
volatile size_t _count;
volatile size_t _max;
public:
void add(ObjectMonitor* monitor);
size_t unlink_deflated(Thread* current, LogStream* ls, elapsedTimer* timer_p,
GrowableArray<ObjectMonitor*>* unlinked_list);
size_t count() const;
size_t max() const;
class Iterator;
Iterator iterator() const;
};
class MonitorList::Iterator {
ObjectMonitor* _current;
public:
Iterator(ObjectMonitor* head) : _current(head) {}
bool has_next() const { return _current != NULL; }
ObjectMonitor* next();
};
class ObjectSynchronizer : AllStatic {
friend class VMStructs;
public:
typedef enum {
inflate_cause_vm_internal = 0,
inflate_cause_monitor_enter = 1,
inflate_cause_wait = 2,
inflate_cause_notify = 3,
inflate_cause_hash_code = 4,
inflate_cause_jni_enter = 5,
inflate_cause_jni_exit = 6,
inflate_cause_nof = 7 // Number of causes
} InflateCause;
typedef enum {
NOT_ENABLED = 0,
FATAL_EXIT = 1,
LOG_WARNING = 2
} SyncDiagnosticOption;
// exit must be implemented non-blocking, since the compiler cannot easily handle
// deoptimization at monitor exit. Hence, it does not take a Handle argument.
// This is the "slow path" version of monitor enter and exit.
static void enter(Handle obj, BasicLock* lock, JavaThread* current);
static void exit(oop obj, BasicLock* lock, JavaThread* current);
// Used only to handle jni locks or other unmatched monitor enter/exit
// Internally they will use heavy weight monitor.
static void jni_enter(Handle obj, JavaThread* current);
static void jni_exit(oop obj, TRAPS);
// Handle all interpreter, compiler and jni cases
static int wait(Handle obj, jlong millis, TRAPS);
static void notify(Handle obj, TRAPS);
static void notifyall(Handle obj, TRAPS);
static bool quick_notify(oopDesc* obj, JavaThread* current, bool All);
static bool quick_enter(oop obj, JavaThread* current, BasicLock* Lock);
// used by classloading to free classloader object lock,
// wait on an internal lock, and reclaim original lock
// with original recursion count
static intx complete_exit(Handle obj, JavaThread* current);
static void reenter (Handle obj, intx recursions, JavaThread* current);
// Inflate light weight monitor to heavy weight monitor
static ObjectMonitor* inflate(Thread* current, oop obj, const InflateCause cause);
// This version is only for internal use
static void inflate_helper(oop obj);
static const char* inflate_cause_name(const InflateCause cause);
// Returns the identity hash value for an oop
// NOTE: It may cause monitor inflation
static intptr_t FastHashCode(Thread* current, oop obj);
// java.lang.Thread support
static bool current_thread_holds_lock(JavaThread* current, Handle h_obj);
static JavaThread* get_lock_owner(ThreadsList * t_list, Handle h_obj);
// JNI detach support
static void release_monitors_owned_by_thread(JavaThread* current);
// Iterate ObjectMonitors where the owner == thread; this does NOT include
// ObjectMonitors where owner is set to a stack lock address in thread:
//
// This version of monitors_iterate() works with the in-use monitor list.
static void monitors_iterate(MonitorClosure* m, JavaThread* thread);
// This version of monitors_iterate() works with the specified linked list.
static void monitors_iterate(MonitorClosure* closure,
ObjectMonitorsHashtable::PtrList* list,
JavaThread* thread);
// Initialize the gInflationLocks
static void initialize();
// GC: we currently use aggressive monitor deflation policy
// Basically we try to deflate all monitors that are not busy.
static size_t deflate_idle_monitors(ObjectMonitorsHashtable* table);
// Deflate idle monitors:
static void chk_for_block_req(JavaThread* current, const char* op_name,
const char* cnt_name, size_t cnt, LogStream* ls,
elapsedTimer* timer_p);
static size_t deflate_monitor_list(Thread* current, LogStream* ls, elapsedTimer* timer_p,
ObjectMonitorsHashtable* table);
static size_t in_use_list_ceiling();
static void dec_in_use_list_ceiling();
static void inc_in_use_list_ceiling();
static void set_in_use_list_ceiling(size_t new_value);
static bool is_async_deflation_needed();
static bool is_async_deflation_requested() { return _is_async_deflation_requested; }
static bool is_final_audit() { return _is_final_audit; }
static void set_is_final_audit() { _is_final_audit = true; }
static jlong last_async_deflation_time_ns() { return _last_async_deflation_time_ns; }
static bool request_deflate_idle_monitors(); // for whitebox test support
static void set_is_async_deflation_requested(bool new_value) { _is_async_deflation_requested = new_value; }
static jlong time_since_last_async_deflation_ms();
// debugging
static void audit_and_print_stats(bool on_exit);
static void chk_in_use_list(outputStream* out, int* error_cnt_p);
static void chk_in_use_entry(ObjectMonitor* n, outputStream* out,
int* error_cnt_p);
static void do_final_audit_and_print_stats();
static void log_in_use_monitor_details(outputStream* out);
private:
friend class SynchronizerTest;
static MonitorList _in_use_list;
static volatile bool _is_async_deflation_requested;
static volatile bool _is_final_audit;
static jlong _last_async_deflation_time_ns;
// Support for SynchronizerTest access to GVars fields:
static u_char* get_gvars_addr();
static u_char* get_gvars_hc_sequence_addr();
static size_t get_gvars_size();
static u_char* get_gvars_stw_random_addr();
static void handle_sync_on_value_based_class(Handle obj, JavaThread* current);
};
// ObjectLocker enforces balanced locking and can never throw an
// IllegalMonitorStateException. However, a pending exception may
// have to pass through, and we must also be able to deal with
// asynchronous exceptions. The caller is responsible for checking
// the thread's pending exception if needed.
class ObjectLocker : public StackObj {
private:
JavaThread* _thread;
Handle _obj;
BasicLock _lock;
public:
ObjectLocker(Handle obj, JavaThread* current);
~ObjectLocker();
// Monitor behavior
void wait(TRAPS) { ObjectSynchronizer::wait(_obj, 0, CHECK); } // wait forever
void notify_all(TRAPS) { ObjectSynchronizer::notifyall(_obj, CHECK); }
};
#endif // SHARE_RUNTIME_SYNCHRONIZER_HPP
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