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/*
* Copyright (c) 1998, 2021, 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_VMTHREAD_HPP
#define SHARE_RUNTIME_VMTHREAD_HPP
#include "runtime/atomic.hpp"
#include "runtime/javaThread.hpp"
#include "runtime/perfDataTypes.hpp"
#include "runtime/nonJavaThread.hpp"
#include "runtime/task.hpp"
#include "runtime/vmOperation.hpp"
// VM operation timeout handling: warn or abort the VM when VM operation takes
// too long. Periodic tasks do not participate in safepoint protocol, and therefore
// can fire when application threads are stopped.
class VMOperationTimeoutTask : public PeriodicTask {
private:
volatile int _armed;
jlong _arm_time;
const char* _vm_op_name;
public:
VMOperationTimeoutTask(size_t interval_time) :
PeriodicTask(interval_time), _armed(0), _arm_time(0), _vm_op_name(nullptr) {}
virtual void task();
bool is_armed();
void arm(const char* vm_op_name);
void disarm();
};
//
// A single VMThread is used by other threads to offload heavy vm operations
// like scavenge, garbage_collect etc.
//
class VMThread: public NamedThread {
private:
volatile bool _is_running;
static ThreadPriority _current_priority;
static bool _should_terminate;
static bool _terminated;
static Monitor * _terminate_lock;
static PerfCounter* _perf_accumulated_vm_operation_time;
static VMOperationTimeoutTask* _timeout_task;
static bool handshake_alot();
static void setup_periodic_safepoint_if_needed();
void evaluate_operation(VM_Operation* op);
void inner_execute(VM_Operation* op);
void wait_for_operation();
// Constructor
VMThread();
// No destruction allowed
~VMThread() {
guarantee(false, "VMThread deletion must fix the race with VM termination");
}
// The ever running loop for the VMThread
void loop();
public:
bool is_running() const { return Atomic::load(&_is_running); }
// Tester
bool is_VM_thread() const { return true; }
// Called to stop the VM thread
static void wait_for_vm_thread_exit();
static bool should_terminate() { return _should_terminate; }
static bool is_terminated() { return _terminated == true; }
// Execution of vm operation
static void execute(VM_Operation* op);
// Returns the current vm operation if any.
static VM_Operation* vm_operation() {
assert(Thread::current()->is_VM_thread(), "Must be");
return _cur_vm_operation;
}
static VM_Operation::VMOp_Type vm_op_type() {
VM_Operation* op = vm_operation();
assert(op != NULL, "sanity");
return op->type();
}
// Returns the single instance of VMThread.
static VMThread* vm_thread() { return _vm_thread; }
void verify();
// Performance measurement
static PerfCounter* perf_accumulated_vm_operation_time() {
return _perf_accumulated_vm_operation_time;
}
// Entry for starting vm thread
virtual void run();
// Creations/Destructions
static void create();
static void destroy();
static void wait_until_executed(VM_Operation* op);
// Printing
const char* type_name() const { return "VMThread"; }
private:
// VM_Operation support
static VM_Operation* _cur_vm_operation; // Current VM operation
static VM_Operation* _next_vm_operation; // Next VM operation
bool set_next_operation(VM_Operation *op); // Set the _next_vm_operation if possible.
// Pointer to single-instance of VM thread
static VMThread* _vm_thread;
};
#endif // SHARE_RUNTIME_VMTHREAD_HPP
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