aoqi@0: /*
aoqi@0:  * Copyright (c) 1997, 2014, Oracle and/or its affiliates. All rights reserved.
aoqi@0:  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
aoqi@0:  *
aoqi@0:  * This code is free software; you can redistribute it and/or modify it
aoqi@0:  * under the terms of the GNU General Public License version 2 only, as
aoqi@0:  * published by the Free Software Foundation.
aoqi@0:  *
aoqi@0:  * This code is distributed in the hope that it will be useful, but WITHOUT
aoqi@0:  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
aoqi@0:  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
aoqi@0:  * version 2 for more details (a copy is included in the LICENSE file that
aoqi@0:  * accompanied this code).
aoqi@0:  *
aoqi@0:  * You should have received a copy of the GNU General Public License version
aoqi@0:  * 2 along with this work; if not, write to the Free Software Foundation,
aoqi@0:  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
aoqi@0:  *
aoqi@0:  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
aoqi@0:  * or visit www.oracle.com if you need additional information or have any
aoqi@0:  * questions.
aoqi@0:  *
aoqi@0:  */
aoqi@0: 
aoqi@0: #ifndef SHARE_VM_RUNTIME_SAFEPOINT_HPP
aoqi@0: #define SHARE_VM_RUNTIME_SAFEPOINT_HPP
aoqi@0: 
aoqi@0: #include "asm/assembler.hpp"
aoqi@0: #include "code/nmethod.hpp"
aoqi@0: #include "memory/allocation.hpp"
aoqi@0: #include "runtime/extendedPC.hpp"
aoqi@0: #include "runtime/mutexLocker.hpp"
aoqi@0: #include "runtime/os.hpp"
aoqi@0: #include "utilities/ostream.hpp"
aoqi@0: 
aoqi@0: //
aoqi@0: // Safepoint synchronization
aoqi@0: ////
aoqi@0: // The VMThread or CMS_thread uses the SafepointSynchronize::begin/end
aoqi@0: // methods to enter/exit a safepoint region. The begin method will roll
aoqi@0: // all JavaThreads forward to a safepoint.
aoqi@0: //
aoqi@0: // JavaThreads must use the ThreadSafepointState abstraction (defined in
aoqi@0: // thread.hpp) to indicate that that they are at a safepoint.
aoqi@0: //
aoqi@0: // The Mutex/Condition variable and ObjectLocker classes calls the enter/
aoqi@0: // exit safepoint methods, when a thread is blocked/restarted. Hence, all mutex exter/
aoqi@0: // exit points *must* be at a safepoint.
aoqi@0: 
aoqi@0: 
aoqi@0: class ThreadSafepointState;
aoqi@0: class SnippetCache;
aoqi@0: class nmethod;
aoqi@0: 
aoqi@0: //
aoqi@0: // Implements roll-forward to safepoint (safepoint synchronization)
aoqi@0: //
aoqi@0: class SafepointSynchronize : AllStatic {
aoqi@0:  public:
aoqi@0:   enum SynchronizeState {
aoqi@0:       _not_synchronized = 0,                   // Threads not synchronized at a safepoint
aoqi@0:                                                // Keep this value 0. See the coment in do_call_back()
aoqi@0:       _synchronizing    = 1,                   // Synchronizing in progress
aoqi@0:       _synchronized     = 2                    // All Java threads are stopped at a safepoint. Only VM thread is running
aoqi@0:   };
aoqi@0: 
aoqi@0:   enum SafepointingThread {
aoqi@0:       _null_thread  = 0,
aoqi@0:       _vm_thread    = 1,
aoqi@0:       _other_thread = 2
aoqi@0:   };
aoqi@0: 
aoqi@0:   enum SafepointTimeoutReason {
aoqi@0:     _spinning_timeout = 0,
aoqi@0:     _blocking_timeout = 1
aoqi@0:   };
aoqi@0: 
aoqi@0:   typedef struct {
aoqi@0:     float  _time_stamp;                        // record when the current safepoint occurs in seconds
aoqi@0:     int    _vmop_type;                         // type of VM operation triggers the safepoint
aoqi@0:     int    _nof_total_threads;                 // total number of Java threads
aoqi@0:     int    _nof_initial_running_threads;       // total number of initially seen running threads
aoqi@0:     int    _nof_threads_wait_to_block;         // total number of threads waiting for to block
aoqi@0:     bool   _page_armed;                        // true if polling page is armed, false otherwise
aoqi@0:     int    _nof_threads_hit_page_trap;         // total number of threads hitting the page trap
aoqi@0:     jlong  _time_to_spin;                      // total time in millis spent in spinning
aoqi@0:     jlong  _time_to_wait_to_block;             // total time in millis spent in waiting for to block
aoqi@0:     jlong  _time_to_do_cleanups;               // total time in millis spent in performing cleanups
aoqi@0:     jlong  _time_to_sync;                      // total time in millis spent in getting to _synchronized
aoqi@0:     jlong  _time_to_exec_vmop;                 // total time in millis spent in vm operation itself
aoqi@0:   } SafepointStats;
aoqi@0: 
aoqi@0:  private:
aoqi@0:   static volatile SynchronizeState _state;     // Threads might read this flag directly, without acquireing the Threads_lock
aoqi@0:   static volatile int _waiting_to_block;       // number of threads we are waiting for to block
aoqi@0:   static int _current_jni_active_count;        // Counts the number of active critical natives during the safepoint
aoqi@0: 
aoqi@0:   // This counter is used for fast versions of jni_Get<Primitive>Field.
aoqi@0:   // An even value means there is no ongoing safepoint operations.
aoqi@0:   // The counter is incremented ONLY at the beginning and end of each
aoqi@0:   // safepoint. The fact that Threads_lock is held throughout each pair of
aoqi@0:   // increments (at the beginning and end of each safepoint) guarantees
aoqi@0:   // race freedom.
aoqi@0: public:
aoqi@0:   static volatile int _safepoint_counter;
aoqi@0: private:
aoqi@0:   static long       _end_of_last_safepoint;     // Time of last safepoint in milliseconds
aoqi@0: 
aoqi@0:   // statistics
aoqi@0:   static jlong            _safepoint_begin_time;     // time when safepoint begins
aoqi@0:   static SafepointStats*  _safepoint_stats;          // array of SafepointStats struct
aoqi@0:   static int              _cur_stat_index;           // current index to the above array
aoqi@0:   static julong           _safepoint_reasons[];      // safepoint count for each VM op
aoqi@0:   static julong           _coalesced_vmop_count;     // coalesced vmop count
aoqi@0:   static jlong            _max_sync_time;            // maximum sync time in nanos
aoqi@0:   static jlong            _max_vmop_time;            // maximum vm operation time in nanos
aoqi@0:   static float            _ts_of_current_safepoint;  // time stamp of current safepoint in seconds
aoqi@0: 
aoqi@0:   static void begin_statistics(int nof_threads, int nof_running);
aoqi@0:   static void update_statistics_on_spin_end();
aoqi@0:   static void update_statistics_on_sync_end(jlong end_time);
aoqi@0:   static void update_statistics_on_cleanup_end(jlong end_time);
aoqi@0:   static void end_statistics(jlong end_time);
aoqi@0:   static void print_statistics();
aoqi@0:   inline static void inc_page_trap_count() {
aoqi@0:     Atomic::inc(&_safepoint_stats[_cur_stat_index]._nof_threads_hit_page_trap);
aoqi@0:   }
aoqi@0: 
aoqi@0:   // For debug long safepoint
aoqi@0:   static void print_safepoint_timeout(SafepointTimeoutReason timeout_reason);
aoqi@0: 
aoqi@0: public:
aoqi@0: 
aoqi@0:   // Main entry points
aoqi@0: 
aoqi@0:   // Roll all threads forward to safepoint. Must be called by the
aoqi@0:   // VMThread or CMS_thread.
aoqi@0:   static void begin();
aoqi@0:   static void end();                    // Start all suspended threads again...
aoqi@0: 
aoqi@0:   static bool safepoint_safe(JavaThread *thread, JavaThreadState state);
aoqi@0: 
aoqi@0:   static void check_for_lazy_critical_native(JavaThread *thread, JavaThreadState state);
aoqi@0: 
aoqi@0:   // Query
aoqi@0:   inline static bool is_at_safepoint()   { return _state == _synchronized;  }
aoqi@0:   inline static bool is_synchronizing()  { return _state == _synchronizing;  }
aoqi@0: 
aoqi@0:   inline static bool do_call_back() {
aoqi@0:     return (_state != _not_synchronized);
aoqi@0:   }
aoqi@0: 
aoqi@0:   inline static void increment_jni_active_count() {
aoqi@0:     assert_locked_or_safepoint(Safepoint_lock);
aoqi@0:     _current_jni_active_count++;
aoqi@0:   }
aoqi@0: 
aoqi@0:   // Called when a thread volantary blocks
aoqi@0:   static void   block(JavaThread *thread);
aoqi@0:   static void   signal_thread_at_safepoint()              { _waiting_to_block--; }
aoqi@0: 
aoqi@0:   // Exception handling for page polling
aoqi@0:   static void handle_polling_page_exception(JavaThread *thread);
aoqi@0: 
aoqi@0:   // VM Thread interface for determining safepoint rate
aoqi@0:   static long last_non_safepoint_interval() {
aoqi@0:     return os::javaTimeMillis() - _end_of_last_safepoint;
aoqi@0:   }
aoqi@0:   static long end_of_last_safepoint() {
aoqi@0:     return _end_of_last_safepoint;
aoqi@0:   }
aoqi@0:   static bool is_cleanup_needed();
aoqi@0:   static void do_cleanup_tasks();
aoqi@0: 
aoqi@0:   // debugging
aoqi@0:   static void print_state()                                PRODUCT_RETURN;
aoqi@0:   static void safepoint_msg(const char* format, ...) ATTRIBUTE_PRINTF(1, 2) PRODUCT_RETURN;
aoqi@0: 
aoqi@0:   static void deferred_initialize_stat();
aoqi@0:   static void print_stat_on_exit();
aoqi@0:   inline static void inc_vmop_coalesced_count() { _coalesced_vmop_count++; }
aoqi@0: 
aoqi@0:   static void set_is_at_safepoint()                        { _state = _synchronized; }
aoqi@0:   static void set_is_not_at_safepoint()                    { _state = _not_synchronized; }
aoqi@0: 
aoqi@0:   // assembly support
aoqi@0:   static address address_of_state()                        { return (address)&_state; }
aoqi@0: 
aoqi@0:   static address safepoint_counter_addr()                  { return (address)&_safepoint_counter; }
aoqi@0: };
aoqi@0: 
aoqi@0: // State class for a thread suspended at a safepoint
aoqi@0: class ThreadSafepointState: public CHeapObj<mtInternal> {
aoqi@0:  public:
aoqi@0:   // These states are maintained by VM thread while threads are being brought
aoqi@0:   // to a safepoint.  After SafepointSynchronize::end(), they are reset to
aoqi@0:   // _running.
aoqi@0:   enum suspend_type {
aoqi@0:     _running                =  0, // Thread state not yet determined (i.e., not at a safepoint yet)
aoqi@0:     _at_safepoint           =  1, // Thread at a safepoint (f.ex., when blocked on a lock)
aoqi@0:     _call_back              =  2  // Keep executing and wait for callback (if thread is in interpreted or vm)
aoqi@0:   };
aoqi@0:  private:
aoqi@0:   volatile bool _at_poll_safepoint;  // At polling page safepoint (NOT a poll return safepoint)
aoqi@0:   // Thread has called back the safepoint code (for debugging)
aoqi@0:   bool                           _has_called_back;
aoqi@0: 
aoqi@0:   JavaThread *                   _thread;
aoqi@0:   volatile suspend_type          _type;
aoqi@0:   JavaThreadState                _orig_thread_state;
aoqi@0: 
aoqi@0: 
aoqi@0:  public:
aoqi@0:   ThreadSafepointState(JavaThread *thread);
aoqi@0: 
aoqi@0:   // examine/roll-forward/restart
aoqi@0:   void examine_state_of_thread();
aoqi@0:   void roll_forward(suspend_type type);
aoqi@0:   void restart();
aoqi@0: 
aoqi@0:   // Query
aoqi@0:   JavaThread*  thread() const         { return _thread; }
aoqi@0:   suspend_type type() const           { return _type; }
aoqi@0:   bool         is_running() const     { return (_type==_running); }
aoqi@0:   JavaThreadState orig_thread_state() const { return _orig_thread_state; }
aoqi@0: 
aoqi@0:   // Support for safepoint timeout (debugging)
aoqi@0:   bool has_called_back() const                   { return _has_called_back; }
aoqi@0:   void set_has_called_back(bool val)             { _has_called_back = val; }
aoqi@0:   bool              is_at_poll_safepoint() { return _at_poll_safepoint; }
aoqi@0:   void              set_at_poll_safepoint(bool val) { _at_poll_safepoint = val; }
aoqi@0: 
aoqi@0:   void handle_polling_page_exception();
aoqi@0: 
aoqi@0:   // debugging
aoqi@0:   void print_on(outputStream* st) const;
aoqi@0:   void print() const                        { print_on(tty); }
aoqi@0: 
aoqi@0:   // Initialize
aoqi@0:   static void create(JavaThread *thread);
aoqi@0:   static void destroy(JavaThread *thread);
aoqi@0: 
aoqi@0:   void safepoint_msg(const char* format, ...) ATTRIBUTE_PRINTF(2, 3) {
aoqi@0:     if (ShowSafepointMsgs) {
aoqi@0:       va_list ap;
aoqi@0:       va_start(ap, format);
aoqi@0:       tty->vprint_cr(format, ap);
aoqi@0:       va_end(ap);
aoqi@0:     }
aoqi@0:   }
aoqi@0: };
aoqi@0: 
aoqi@0: 
aoqi@0: 
aoqi@0: #endif // SHARE_VM_RUNTIME_SAFEPOINT_HPP