70 }
71
72 void JfrPostBox::post(JFR_Msg msg) {
73 const int the_message = MSGBIT(msg);
74 if (is_thread_lock_aversive()) {
75 deposit(the_message);
76 return;
77 }
78 if (!is_synchronous(the_message)) {
79 asynchronous_post(the_message);
80 return;
81 }
82 synchronous_post(the_message);
83 }
84
85 void JfrPostBox::deposit(int new_messages) {
86 while (true) {
87 const int current_msgs = Atomic::load(&_messages);
88 // OR the new message
89 const int exchange_value = current_msgs | new_messages;
90 const int result = Atomic::cmpxchg(exchange_value, &_messages, current_msgs);
91 if (result == current_msgs) {
92 return;
93 }
94 /* Some other thread just set exactly what this thread wanted */
95 if ((result & new_messages) == new_messages) {
96 return;
97 }
98 }
99 }
100
101 void JfrPostBox::asynchronous_post(int msg) {
102 assert(!is_synchronous(msg), "invariant");
103 deposit(msg);
104 JfrMonitorTryLock try_msg_lock(JfrMsg_lock);
105 if (try_msg_lock.acquired()) {
106 JfrMsg_lock->notify_all();
107 }
108 }
109
110 void JfrPostBox::synchronous_post(int msg) {
122 }
123
124 /*
125 * Check if a synchronous message has been processed.
126 * We avoid racing on _msg_handled_serial by ensuring
127 * that we are holding the JfrMsg_lock when checking
128 * completion status.
129 */
130 bool JfrPostBox::is_message_processed(uintptr_t serial_id) const {
131 assert(JfrMsg_lock->owned_by_self(), "_msg_handled_serial must be read under JfrMsg_lock protection");
132 return serial_id <= Atomic::load(&_msg_handled_serial);
133 }
134
135 bool JfrPostBox::is_empty() const {
136 assert(JfrMsg_lock->owned_by_self(), "not holding JfrMsg_lock!");
137 return Atomic::load(&_messages) == 0;
138 }
139
140 int JfrPostBox::collect() {
141 // get pending and reset to 0
142 const int messages = Atomic::xchg(0, &_messages);
143 if (check_waiters(messages)) {
144 _has_waiters = true;
145 assert(JfrMsg_lock->owned_by_self(), "incrementing _msg_read_serial is protected by JfrMsg_lock");
146 // Update made visible on release of JfrMsg_lock via fence instruction in Monitor::IUnlock.
147 ++_msg_read_serial;
148 }
149 return messages;
150 }
151
152 bool JfrPostBox::check_waiters(int messages) const {
153 assert(JfrMsg_lock->owned_by_self(), "not holding JfrMsg_lock!");
154 assert(!_has_waiters, "invariant");
155 return is_synchronous(messages);
156 }
157
158 void JfrPostBox::notify_waiters() {
159 if (!_has_waiters) {
160 return;
161 }
162 _has_waiters = false;
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70 }
71
72 void JfrPostBox::post(JFR_Msg msg) {
73 const int the_message = MSGBIT(msg);
74 if (is_thread_lock_aversive()) {
75 deposit(the_message);
76 return;
77 }
78 if (!is_synchronous(the_message)) {
79 asynchronous_post(the_message);
80 return;
81 }
82 synchronous_post(the_message);
83 }
84
85 void JfrPostBox::deposit(int new_messages) {
86 while (true) {
87 const int current_msgs = Atomic::load(&_messages);
88 // OR the new message
89 const int exchange_value = current_msgs | new_messages;
90 const int result = Atomic::cmpxchg(&_messages, current_msgs, exchange_value);
91 if (result == current_msgs) {
92 return;
93 }
94 /* Some other thread just set exactly what this thread wanted */
95 if ((result & new_messages) == new_messages) {
96 return;
97 }
98 }
99 }
100
101 void JfrPostBox::asynchronous_post(int msg) {
102 assert(!is_synchronous(msg), "invariant");
103 deposit(msg);
104 JfrMonitorTryLock try_msg_lock(JfrMsg_lock);
105 if (try_msg_lock.acquired()) {
106 JfrMsg_lock->notify_all();
107 }
108 }
109
110 void JfrPostBox::synchronous_post(int msg) {
122 }
123
124 /*
125 * Check if a synchronous message has been processed.
126 * We avoid racing on _msg_handled_serial by ensuring
127 * that we are holding the JfrMsg_lock when checking
128 * completion status.
129 */
130 bool JfrPostBox::is_message_processed(uintptr_t serial_id) const {
131 assert(JfrMsg_lock->owned_by_self(), "_msg_handled_serial must be read under JfrMsg_lock protection");
132 return serial_id <= Atomic::load(&_msg_handled_serial);
133 }
134
135 bool JfrPostBox::is_empty() const {
136 assert(JfrMsg_lock->owned_by_self(), "not holding JfrMsg_lock!");
137 return Atomic::load(&_messages) == 0;
138 }
139
140 int JfrPostBox::collect() {
141 // get pending and reset to 0
142 const int messages = Atomic::xchg(&_messages, 0);
143 if (check_waiters(messages)) {
144 _has_waiters = true;
145 assert(JfrMsg_lock->owned_by_self(), "incrementing _msg_read_serial is protected by JfrMsg_lock");
146 // Update made visible on release of JfrMsg_lock via fence instruction in Monitor::IUnlock.
147 ++_msg_read_serial;
148 }
149 return messages;
150 }
151
152 bool JfrPostBox::check_waiters(int messages) const {
153 assert(JfrMsg_lock->owned_by_self(), "not holding JfrMsg_lock!");
154 assert(!_has_waiters, "invariant");
155 return is_synchronous(messages);
156 }
157
158 void JfrPostBox::notify_waiters() {
159 if (!_has_waiters) {
160 return;
161 }
162 _has_waiters = false;
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