aoqi@0: /*
aoqi@0:  * Copyright (c) 2003, 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: #include "precompiled.hpp"
aoqi@0: #include "classfile/systemDictionary.hpp"
aoqi@0: #include "classfile/vmSymbols.hpp"
aoqi@0: #include "oops/oop.inline.hpp"
aoqi@0: #include "runtime/interfaceSupport.hpp"
aoqi@0: #include "runtime/java.hpp"
aoqi@0: #include "runtime/javaCalls.hpp"
aoqi@0: #include "runtime/mutex.hpp"
aoqi@0: #include "runtime/mutexLocker.hpp"
aoqi@0: #include "services/lowMemoryDetector.hpp"
aoqi@0: #include "services/management.hpp"
aoqi@0: 
aoqi@0: volatile bool LowMemoryDetector::_enabled_for_collected_pools = false;
aoqi@0: volatile jint LowMemoryDetector::_disabled_count = 0;
aoqi@0: 
aoqi@0: bool LowMemoryDetector::has_pending_requests() {
aoqi@0:   assert(Service_lock->owned_by_self(), "Must own Service_lock");
aoqi@0:   bool has_requests = false;
aoqi@0:   int num_memory_pools = MemoryService::num_memory_pools();
aoqi@0:   for (int i = 0; i < num_memory_pools; i++) {
aoqi@0:     MemoryPool* pool = MemoryService::get_memory_pool(i);
aoqi@0:     SensorInfo* sensor = pool->usage_sensor();
aoqi@0:     if (sensor != NULL) {
aoqi@0:       has_requests = has_requests || sensor->has_pending_requests();
aoqi@0:     }
aoqi@0: 
aoqi@0:     SensorInfo* gc_sensor = pool->gc_usage_sensor();
aoqi@0:     if (gc_sensor != NULL) {
aoqi@0:       has_requests = has_requests || gc_sensor->has_pending_requests();
aoqi@0:     }
aoqi@0:   }
aoqi@0:   return has_requests;
aoqi@0: }
aoqi@0: 
aoqi@0: void LowMemoryDetector::process_sensor_changes(TRAPS) {
aoqi@0:   ResourceMark rm(THREAD);
aoqi@0:   HandleMark hm(THREAD);
aoqi@0: 
aoqi@0:   // No need to hold Service_lock to call out to Java
aoqi@0:   int num_memory_pools = MemoryService::num_memory_pools();
aoqi@0:   for (int i = 0; i < num_memory_pools; i++) {
aoqi@0:     MemoryPool* pool = MemoryService::get_memory_pool(i);
aoqi@0:     SensorInfo* sensor = pool->usage_sensor();
aoqi@0:     SensorInfo* gc_sensor = pool->gc_usage_sensor();
aoqi@0:     if (sensor != NULL && sensor->has_pending_requests()) {
aoqi@0:       sensor->process_pending_requests(CHECK);
aoqi@0:     }
aoqi@0:     if (gc_sensor != NULL && gc_sensor->has_pending_requests()) {
aoqi@0:       gc_sensor->process_pending_requests(CHECK);
aoqi@0:     }
aoqi@0:   }
aoqi@0: }
aoqi@0: 
aoqi@0: // This method could be called from any Java threads
aoqi@0: // and also VMThread.
aoqi@0: void LowMemoryDetector::detect_low_memory() {
aoqi@0:   MutexLockerEx ml(Service_lock, Mutex::_no_safepoint_check_flag);
aoqi@0: 
aoqi@0:   bool has_pending_requests = false;
aoqi@0:   int num_memory_pools = MemoryService::num_memory_pools();
aoqi@0:   for (int i = 0; i < num_memory_pools; i++) {
aoqi@0:     MemoryPool* pool = MemoryService::get_memory_pool(i);
aoqi@0:     SensorInfo* sensor = pool->usage_sensor();
aoqi@0:     if (sensor != NULL &&
aoqi@0:         pool->usage_threshold()->is_high_threshold_supported() &&
aoqi@0:         pool->usage_threshold()->high_threshold() != 0) {
aoqi@0:       MemoryUsage usage = pool->get_memory_usage();
aoqi@0:       sensor->set_gauge_sensor_level(usage,
aoqi@0:                                      pool->usage_threshold());
aoqi@0:       has_pending_requests = has_pending_requests || sensor->has_pending_requests();
aoqi@0:     }
aoqi@0:   }
aoqi@0: 
aoqi@0:   if (has_pending_requests) {
aoqi@0:     Service_lock->notify_all();
aoqi@0:   }
aoqi@0: }
aoqi@0: 
aoqi@0: // This method could be called from any Java threads
aoqi@0: // and also VMThread.
aoqi@0: void LowMemoryDetector::detect_low_memory(MemoryPool* pool) {
aoqi@0:   SensorInfo* sensor = pool->usage_sensor();
aoqi@0:   if (sensor == NULL ||
aoqi@0:       !pool->usage_threshold()->is_high_threshold_supported() ||
aoqi@0:       pool->usage_threshold()->high_threshold() == 0) {
aoqi@0:     return;
aoqi@0:   }
aoqi@0: 
aoqi@0:   {
aoqi@0:     MutexLockerEx ml(Service_lock, Mutex::_no_safepoint_check_flag);
aoqi@0: 
aoqi@0:     MemoryUsage usage = pool->get_memory_usage();
aoqi@0:     sensor->set_gauge_sensor_level(usage,
aoqi@0:                                    pool->usage_threshold());
aoqi@0:     if (sensor->has_pending_requests()) {
aoqi@0:       // notify sensor state update
aoqi@0:       Service_lock->notify_all();
aoqi@0:     }
aoqi@0:   }
aoqi@0: }
aoqi@0: 
aoqi@0: // Only called by VMThread at GC time
aoqi@0: void LowMemoryDetector::detect_after_gc_memory(MemoryPool* pool) {
aoqi@0:   SensorInfo* sensor = pool->gc_usage_sensor();
aoqi@0:   if (sensor == NULL ||
aoqi@0:       !pool->gc_usage_threshold()->is_high_threshold_supported() ||
aoqi@0:       pool->gc_usage_threshold()->high_threshold() == 0) {
aoqi@0:     return;
aoqi@0:   }
aoqi@0: 
aoqi@0:   {
aoqi@0:     MutexLockerEx ml(Service_lock, Mutex::_no_safepoint_check_flag);
aoqi@0: 
aoqi@0:     MemoryUsage usage = pool->get_last_collection_usage();
aoqi@0:     sensor->set_counter_sensor_level(usage, pool->gc_usage_threshold());
aoqi@0: 
aoqi@0:     if (sensor->has_pending_requests()) {
aoqi@0:       // notify sensor state update
aoqi@0:       Service_lock->notify_all();
aoqi@0:     }
aoqi@0:   }
aoqi@0: }
aoqi@0: 
aoqi@0: // recompute enabled flag
aoqi@0: void LowMemoryDetector::recompute_enabled_for_collected_pools() {
aoqi@0:   bool enabled = false;
aoqi@0:   int num_memory_pools = MemoryService::num_memory_pools();
aoqi@0:   for (int i=0; i<num_memory_pools; i++) {
aoqi@0:     MemoryPool* pool = MemoryService::get_memory_pool(i);
aoqi@0:     if (pool->is_collected_pool() && is_enabled(pool)) {
aoqi@0:       enabled = true;
aoqi@0:       break;
aoqi@0:     }
aoqi@0:   }
aoqi@0:   _enabled_for_collected_pools = enabled;
aoqi@0: }
aoqi@0: 
aoqi@0: SensorInfo::SensorInfo() {
aoqi@0:   _sensor_obj = NULL;
aoqi@0:   _sensor_on = false;
aoqi@0:   _sensor_count = 0;
aoqi@0:   _pending_trigger_count = 0;
aoqi@0:   _pending_clear_count = 0;
aoqi@0: }
aoqi@0: 
aoqi@0: // When this method is used, the memory usage is monitored
aoqi@0: // as a gauge attribute.  Sensor notifications (trigger or
aoqi@0: // clear) is only emitted at the first time it crosses
aoqi@0: // a threshold.
aoqi@0: //
aoqi@0: // High and low thresholds are designed to provide a
aoqi@0: // hysteresis mechanism to avoid repeated triggering
aoqi@0: // of notifications when the attribute value makes small oscillations
aoqi@0: // around the high or low threshold value.
aoqi@0: //
aoqi@0: // The sensor will be triggered if:
aoqi@0: //  (1) the usage is crossing above the high threshold and
aoqi@0: //      the sensor is currently off and no pending
aoqi@0: //      trigger requests; or
aoqi@0: //  (2) the usage is crossing above the high threshold and
aoqi@0: //      the sensor will be off (i.e. sensor is currently on
aoqi@0: //      and has pending clear requests).
aoqi@0: //
aoqi@0: // Subsequent crossings of the high threshold value do not cause
aoqi@0: // any triggers unless the usage becomes less than the low threshold.
aoqi@0: //
aoqi@0: // The sensor will be cleared if:
aoqi@0: //  (1) the usage is crossing below the low threshold and
aoqi@0: //      the sensor is currently on and no pending
aoqi@0: //      clear requests; or
aoqi@0: //  (2) the usage is crossing below the low threshold and
aoqi@0: //      the sensor will be on (i.e. sensor is currently off
aoqi@0: //      and has pending trigger requests).
aoqi@0: //
aoqi@0: // Subsequent crossings of the low threshold value do not cause
aoqi@0: // any clears unless the usage becomes greater than or equal
aoqi@0: // to the high threshold.
aoqi@0: //
aoqi@0: // If the current level is between high and low threhsold, no change.
aoqi@0: //
aoqi@0: void SensorInfo::set_gauge_sensor_level(MemoryUsage usage, ThresholdSupport* high_low_threshold) {
aoqi@0:   assert(high_low_threshold->is_high_threshold_supported(), "just checking");
aoqi@0: 
aoqi@0:   bool is_over_high = high_low_threshold->is_high_threshold_crossed(usage);
aoqi@0:   bool is_below_low = high_low_threshold->is_low_threshold_crossed(usage);
aoqi@0: 
aoqi@0:   assert(!(is_over_high && is_below_low), "Can't be both true");
aoqi@0: 
aoqi@0:   if (is_over_high &&
aoqi@0:         ((!_sensor_on && _pending_trigger_count == 0) ||
aoqi@0:          _pending_clear_count > 0)) {
aoqi@0:     // low memory detected and need to increment the trigger pending count
aoqi@0:     // if the sensor is off or will be off due to _pending_clear_ > 0
aoqi@0:     // Request to trigger the sensor
aoqi@0:     _pending_trigger_count++;
aoqi@0:     _usage = usage;
aoqi@0: 
aoqi@0:     if (_pending_clear_count > 0) {
aoqi@0:       // non-zero pending clear requests indicates that there are
aoqi@0:       // pending requests to clear this sensor.
aoqi@0:       // This trigger request needs to clear this clear count
aoqi@0:       // since the resulting sensor flag should be on.
aoqi@0:       _pending_clear_count = 0;
aoqi@0:     }
aoqi@0:   } else if (is_below_low &&
aoqi@0:                ((_sensor_on && _pending_clear_count == 0) ||
aoqi@0:                 (_pending_trigger_count > 0 && _pending_clear_count == 0))) {
aoqi@0:     // memory usage returns below the threshold
aoqi@0:     // Request to clear the sensor if the sensor is on or will be on due to
aoqi@0:     // _pending_trigger_count > 0 and also no clear request
aoqi@0:     _pending_clear_count++;
aoqi@0:   }
aoqi@0: }
aoqi@0: 
aoqi@0: // When this method is used, the memory usage is monitored as a
aoqi@0: // simple counter attribute.  The sensor will be triggered
aoqi@0: // whenever the usage is crossing the threshold to keep track
aoqi@0: // of the number of times the VM detects such a condition occurs.
aoqi@0: //
aoqi@0: // High and low thresholds are designed to provide a
aoqi@0: // hysteresis mechanism to avoid repeated triggering
aoqi@0: // of notifications when the attribute value makes small oscillations
aoqi@0: // around the high or low threshold value.
aoqi@0: //
aoqi@0: // The sensor will be triggered if:
aoqi@0: //   - the usage is crossing above the high threshold regardless
aoqi@0: //     of the current sensor state.
aoqi@0: //
aoqi@0: // The sensor will be cleared if:
aoqi@0: //  (1) the usage is crossing below the low threshold and
aoqi@0: //      the sensor is currently on; or
aoqi@0: //  (2) the usage is crossing below the low threshold and
aoqi@0: //      the sensor will be on (i.e. sensor is currently off
aoqi@0: //      and has pending trigger requests).
aoqi@0: void SensorInfo::set_counter_sensor_level(MemoryUsage usage, ThresholdSupport* counter_threshold) {
aoqi@0:   assert(counter_threshold->is_high_threshold_supported(), "just checking");
aoqi@0: 
aoqi@0:   bool is_over_high = counter_threshold->is_high_threshold_crossed(usage);
aoqi@0:   bool is_below_low = counter_threshold->is_low_threshold_crossed(usage);
aoqi@0: 
aoqi@0:   assert(!(is_over_high && is_below_low), "Can't be both true");
aoqi@0: 
aoqi@0:   if (is_over_high) {
aoqi@0:     _pending_trigger_count++;
aoqi@0:     _usage = usage;
aoqi@0:     _pending_clear_count = 0;
aoqi@0:   } else if (is_below_low && (_sensor_on || _pending_trigger_count > 0)) {
aoqi@0:     _pending_clear_count++;
aoqi@0:   }
aoqi@0: }
aoqi@0: 
aoqi@0: void SensorInfo::oops_do(OopClosure* f) {
aoqi@0:   f->do_oop((oop*) &_sensor_obj);
aoqi@0: }
aoqi@0: 
aoqi@0: void SensorInfo::process_pending_requests(TRAPS) {
aoqi@0:   if (!has_pending_requests()) {
aoqi@0:     return;
aoqi@0:   }
aoqi@0: 
aoqi@0:   int pending_count = pending_trigger_count();
aoqi@0:   if (pending_clear_count() > 0) {
aoqi@0:     clear(pending_count, CHECK);
aoqi@0:   } else {
aoqi@0:     trigger(pending_count, CHECK);
aoqi@0:   }
aoqi@0: 
aoqi@0: }
aoqi@0: 
aoqi@0: void SensorInfo::trigger(int count, TRAPS) {
aoqi@0:   assert(count <= _pending_trigger_count, "just checking");
aoqi@0: 
aoqi@0:   if (_sensor_obj != NULL) {
aoqi@0:     Klass* k = Management::sun_management_Sensor_klass(CHECK);
aoqi@0:     instanceKlassHandle sensorKlass (THREAD, k);
aoqi@0:     Handle sensor_h(THREAD, _sensor_obj);
aoqi@0:     Handle usage_h = MemoryService::create_MemoryUsage_obj(_usage, CHECK);
aoqi@0: 
aoqi@0:     JavaValue result(T_VOID);
aoqi@0:     JavaCallArguments args(sensor_h);
aoqi@0:     args.push_int((int) count);
aoqi@0:     args.push_oop(usage_h);
aoqi@0: 
aoqi@0:     JavaCalls::call_virtual(&result,
aoqi@0:                             sensorKlass,
aoqi@0:                             vmSymbols::trigger_name(),
aoqi@0:                             vmSymbols::trigger_method_signature(),
aoqi@0:                             &args,
aoqi@0:                             CHECK);
aoqi@0:   }
aoqi@0: 
aoqi@0:   {
aoqi@0:     // Holds Service_lock and update the sensor state
aoqi@0:     MutexLockerEx ml(Service_lock, Mutex::_no_safepoint_check_flag);
aoqi@0:     _sensor_on = true;
aoqi@0:     _sensor_count += count;
aoqi@0:     _pending_trigger_count = _pending_trigger_count - count;
aoqi@0:   }
aoqi@0: }
aoqi@0: 
aoqi@0: void SensorInfo::clear(int count, TRAPS) {
aoqi@0:   if (_sensor_obj != NULL) {
aoqi@0:     Klass* k = Management::sun_management_Sensor_klass(CHECK);
aoqi@0:     instanceKlassHandle sensorKlass (THREAD, k);
aoqi@0:     Handle sensor(THREAD, _sensor_obj);
aoqi@0: 
aoqi@0:     JavaValue result(T_VOID);
aoqi@0:     JavaCallArguments args(sensor);
aoqi@0:     args.push_int((int) count);
aoqi@0:     JavaCalls::call_virtual(&result,
aoqi@0:                             sensorKlass,
aoqi@0:                             vmSymbols::clear_name(),
aoqi@0:                             vmSymbols::int_void_signature(),
aoqi@0:                             &args,
aoqi@0:                             CHECK);
aoqi@0:   }
aoqi@0: 
aoqi@0:   {
aoqi@0:     // Holds Service_lock and update the sensor state
aoqi@0:     MutexLockerEx ml(Service_lock, Mutex::_no_safepoint_check_flag);
aoqi@0:     _sensor_on = false;
aoqi@0:     _pending_clear_count = 0;
aoqi@0:     _pending_trigger_count = _pending_trigger_count - count;
aoqi@0:   }
aoqi@0: }
aoqi@0: 
aoqi@0: //--------------------------------------------------------------
aoqi@0: // Non-product code
aoqi@0: 
aoqi@0: #ifndef PRODUCT
aoqi@0: void SensorInfo::print() {
aoqi@0:   tty->print_cr("%s count = " SIZE_FORMAT " pending_triggers = %d pending_clears = %d",
aoqi@0:                 (_sensor_on ? "on" : "off"),
aoqi@0:                 _sensor_count, _pending_trigger_count, _pending_clear_count);
aoqi@0: }
aoqi@0: 
aoqi@0: #endif // PRODUCT