--- /dev/null Thu Jan 01 00:00:00 1970 +0000
+++ b/src/hotspot/share/runtime/safepoint.hpp Tue Sep 12 19:03:39 2017 +0200
@@ -0,0 +1,268 @@
+/*
+ * Copyright (c) 1997, 2017, 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_SAFEPOINT_HPP
+#define SHARE_VM_RUNTIME_SAFEPOINT_HPP
+
+#include "asm/assembler.hpp"
+#include "code/nmethod.hpp"
+#include "memory/allocation.hpp"
+#include "runtime/extendedPC.hpp"
+#include "runtime/mutexLocker.hpp"
+#include "runtime/os.hpp"
+#include "utilities/ostream.hpp"
+
+//
+// Safepoint synchronization
+////
+// The VMThread or CMS_thread uses the SafepointSynchronize::begin/end
+// methods to enter/exit a safepoint region. The begin method will roll
+// all JavaThreads forward to a safepoint.
+//
+// JavaThreads must use the ThreadSafepointState abstraction (defined in
+// thread.hpp) to indicate that that they are at a safepoint.
+//
+// The Mutex/Condition variable and ObjectLocker classes calls the enter/
+// exit safepoint methods, when a thread is blocked/restarted. Hence, all mutex exter/
+// exit points *must* be at a safepoint.
+
+
+class ThreadSafepointState;
+class SnippetCache;
+class nmethod;
+
+//
+// Implements roll-forward to safepoint (safepoint synchronization)
+//
+class SafepointSynchronize : AllStatic {
+ public:
+ enum SynchronizeState {
+ _not_synchronized = 0, // Threads not synchronized at a safepoint
+ // Keep this value 0. See the comment in do_call_back()
+ _synchronizing = 1, // Synchronizing in progress
+ _synchronized = 2 // All Java threads are stopped at a safepoint. Only VM thread is running
+ };
+
+ enum SafepointingThread {
+ _null_thread = 0,
+ _vm_thread = 1,
+ _other_thread = 2
+ };
+
+ enum SafepointTimeoutReason {
+ _spinning_timeout = 0,
+ _blocking_timeout = 1
+ };
+
+ // The enums are listed in the order of the tasks when done serially.
+ enum SafepointCleanupTasks {
+ SAFEPOINT_CLEANUP_DEFLATE_MONITORS,
+ SAFEPOINT_CLEANUP_UPDATE_INLINE_CACHES,
+ SAFEPOINT_CLEANUP_COMPILATION_POLICY,
+ SAFEPOINT_CLEANUP_SYMBOL_TABLE_REHASH,
+ SAFEPOINT_CLEANUP_STRING_TABLE_REHASH,
+ SAFEPOINT_CLEANUP_CLD_PURGE,
+ // Leave this one last.
+ SAFEPOINT_CLEANUP_NUM_TASKS
+ };
+
+ typedef struct {
+ float _time_stamp; // record when the current safepoint occurs in seconds
+ int _vmop_type; // type of VM operation triggers the safepoint
+ int _nof_total_threads; // total number of Java threads
+ int _nof_initial_running_threads; // total number of initially seen running threads
+ int _nof_threads_wait_to_block; // total number of threads waiting for to block
+ bool _page_armed; // true if polling page is armed, false otherwise
+ int _nof_threads_hit_page_trap; // total number of threads hitting the page trap
+ jlong _time_to_spin; // total time in millis spent in spinning
+ jlong _time_to_wait_to_block; // total time in millis spent in waiting for to block
+ jlong _time_to_do_cleanups; // total time in millis spent in performing cleanups
+ jlong _time_to_sync; // total time in millis spent in getting to _synchronized
+ jlong _time_to_exec_vmop; // total time in millis spent in vm operation itself
+ } SafepointStats;
+
+ private:
+ static volatile SynchronizeState _state; // Threads might read this flag directly, without acquiring the Threads_lock
+ static volatile int _waiting_to_block; // number of threads we are waiting for to block
+ static int _current_jni_active_count; // Counts the number of active critical natives during the safepoint
+
+ // This counter is used for fast versions of jni_Get<Primitive>Field.
+ // An even value means there is no ongoing safepoint operations.
+ // The counter is incremented ONLY at the beginning and end of each
+ // safepoint. The fact that Threads_lock is held throughout each pair of
+ // increments (at the beginning and end of each safepoint) guarantees
+ // race freedom.
+public:
+ static volatile int _safepoint_counter;
+private:
+ static long _end_of_last_safepoint; // Time of last safepoint in milliseconds
+
+ // Statistics
+ static jlong _safepoint_begin_time; // time when safepoint begins
+ static SafepointStats* _safepoint_stats; // array of SafepointStats struct
+ static int _cur_stat_index; // current index to the above array
+ static julong _safepoint_reasons[]; // safepoint count for each VM op
+ static julong _coalesced_vmop_count; // coalesced vmop count
+ static jlong _max_sync_time; // maximum sync time in nanos
+ static jlong _max_vmop_time; // maximum vm operation time in nanos
+ static float _ts_of_current_safepoint; // time stamp of current safepoint in seconds
+
+ static void begin_statistics(int nof_threads, int nof_running);
+ static void update_statistics_on_spin_end();
+ static void update_statistics_on_sync_end(jlong end_time);
+ static void update_statistics_on_cleanup_end(jlong end_time);
+ static void end_statistics(jlong end_time);
+ static void print_statistics();
+ inline static void inc_page_trap_count() {
+ Atomic::inc(&_safepoint_stats[_cur_stat_index]._nof_threads_hit_page_trap);
+ }
+
+ // For debug long safepoint
+ static void print_safepoint_timeout(SafepointTimeoutReason timeout_reason);
+
+public:
+
+ // Main entry points
+
+ // Roll all threads forward to safepoint. Must be called by the
+ // VMThread or CMS_thread.
+ static void begin();
+ static void end(); // Start all suspended threads again...
+
+ static bool safepoint_safe(JavaThread *thread, JavaThreadState state);
+
+ static void check_for_lazy_critical_native(JavaThread *thread, JavaThreadState state);
+
+ // Query
+ inline static bool is_at_safepoint() { return _state == _synchronized; }
+ inline static bool is_synchronizing() { return _state == _synchronizing; }
+ inline static int safepoint_counter() { return _safepoint_counter; }
+
+ inline static bool do_call_back() {
+ return (_state != _not_synchronized);
+ }
+
+ inline static void increment_jni_active_count() {
+ assert_locked_or_safepoint(Safepoint_lock);
+ _current_jni_active_count++;
+ }
+
+ // Called when a thread voluntarily blocks
+ static void block(JavaThread *thread);
+ static void signal_thread_at_safepoint() { _waiting_to_block--; }
+
+ // Exception handling for page polling
+ static void handle_polling_page_exception(JavaThread *thread);
+
+ // VM Thread interface for determining safepoint rate
+ static long last_non_safepoint_interval() {
+ return os::javaTimeMillis() - _end_of_last_safepoint;
+ }
+ static long end_of_last_safepoint() {
+ return _end_of_last_safepoint;
+ }
+ static bool is_cleanup_needed();
+ static void do_cleanup_tasks();
+
+ // Debugging
+ static void print_state() PRODUCT_RETURN;
+ static void safepoint_msg(const char* format, ...) ATTRIBUTE_PRINTF(1, 2) PRODUCT_RETURN;
+
+ static void deferred_initialize_stat();
+ static void print_stat_on_exit();
+ inline static void inc_vmop_coalesced_count() { _coalesced_vmop_count++; }
+
+ static void set_is_at_safepoint() { _state = _synchronized; }
+ static void set_is_not_at_safepoint() { _state = _not_synchronized; }
+
+ // Assembly support
+ static address address_of_state() { return (address)&_state; }
+
+ static address safepoint_counter_addr() { return (address)&_safepoint_counter; }
+};
+
+// State class for a thread suspended at a safepoint
+class ThreadSafepointState: public CHeapObj<mtInternal> {
+ public:
+ // These states are maintained by VM thread while threads are being brought
+ // to a safepoint. After SafepointSynchronize::end(), they are reset to
+ // _running.
+ enum suspend_type {
+ _running = 0, // Thread state not yet determined (i.e., not at a safepoint yet)
+ _at_safepoint = 1, // Thread at a safepoint (f.ex., when blocked on a lock)
+ _call_back = 2 // Keep executing and wait for callback (if thread is in interpreted or vm)
+ };
+ private:
+ volatile bool _at_poll_safepoint; // At polling page safepoint (NOT a poll return safepoint)
+ // Thread has called back the safepoint code (for debugging)
+ bool _has_called_back;
+
+ JavaThread * _thread;
+ volatile suspend_type _type;
+ JavaThreadState _orig_thread_state;
+
+
+ public:
+ ThreadSafepointState(JavaThread *thread);
+
+ // examine/roll-forward/restart
+ void examine_state_of_thread();
+ void roll_forward(suspend_type type);
+ void restart();
+
+ // Query
+ JavaThread* thread() const { return _thread; }
+ suspend_type type() const { return _type; }
+ bool is_running() const { return (_type==_running); }
+ JavaThreadState orig_thread_state() const { return _orig_thread_state; }
+
+ // Support for safepoint timeout (debugging)
+ bool has_called_back() const { return _has_called_back; }
+ void set_has_called_back(bool val) { _has_called_back = val; }
+ bool is_at_poll_safepoint() { return _at_poll_safepoint; }
+ void set_at_poll_safepoint(bool val) { _at_poll_safepoint = val; }
+
+ void handle_polling_page_exception();
+
+ // debugging
+ void print_on(outputStream* st) const;
+ void print() const { print_on(tty); }
+
+ // Initialize
+ static void create(JavaThread *thread);
+ static void destroy(JavaThread *thread);
+
+ void safepoint_msg(const char* format, ...) ATTRIBUTE_PRINTF(2, 3) {
+ if (ShowSafepointMsgs) {
+ va_list ap;
+ va_start(ap, format);
+ tty->vprint_cr(format, ap);
+ va_end(ap);
+ }
+ }
+};
+
+
+
+#endif // SHARE_VM_RUNTIME_SAFEPOINT_HPP