1 /* 2 * Copyright (c) 2018, Google and/or its affiliates. All rights reserved. 3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. 4 * 5 * This code is free software; you can redistribute it and/or modify it 6 * under the terms of the GNU General Public License version 2 only, as 7 * published by the Free Software Foundation. 8 * 9 * This code is distributed in the hope that it will be useful, but WITHOUT 10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or 11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License 12 * version 2 for more details (a copy is included in the LICENSE file that 13 * accompanied this code). 14 * 15 * You should have received a copy of the GNU General Public License version 16 * 2 along with this work; if not, write to the Free Software Foundation, 17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. 18 * 19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA 20 * or visit www.oracle.com if you need additional information or have any 21 * questions. 22 * 23 */ 24 25 #ifndef RUNTIME_THREADHEAPSAMPLER_HPP 26 #define RUNTIME_THREADHEAPSAMPLER_HPP 27 28 #include "memory/allocation.hpp" 29 #include "runtime/orderAccess.inline.hpp" 30 31 class ThreadHeapSampler { 32 private: 33 size_t _bytes_until_sample; 34 Thread* _thread; 35 // Cheap random number generator 36 static uint64_t _rnd; 37 38 void pick_next_geometric_sample(); 39 void pick_next_sample(size_t overflowed_bytes = 0); 40 static int _enabled; 41 static int _sampling_rate; 42 43 // Used for assertion mode to determine if there is a path to a TLAB slow path 44 // without a collector present. 45 size_t _collectors_present; 46 47 static void init_log_table(); 48 49 public: 50 ThreadHeapSampler() : _bytes_until_sample(0), _thread(NULL) { 51 _rnd = static_cast<uint32_t>(reinterpret_cast<uintptr_t>(this)); 52 if (_rnd == 0) { 53 _rnd = 1; 54 } 55 56 _collectors_present = 0; 57 } 58 59 void set_thread(Thread* t) { _thread = t; } 60 61 size_t bytes_until_sample() { return _bytes_until_sample; } 62 void set_bytes_until_sample(size_t bytes) { _bytes_until_sample = bytes; } 63 64 void check_for_sampling(HeapWord* obj, size_t size_in_bytes, size_t bytes_allocated_before = 0); 65 66 static int enabled() { return OrderAccess::load_acquire(&_enabled); } 67 static void enable(); 68 static void disable() { OrderAccess::release_store(&_enabled, 0); } 69 70 static void set_sampling_rate(int sampling_rate) { 71 OrderAccess::release_store(&_sampling_rate, sampling_rate); 72 } 73 static int get_sampling_rate() { 74 return OrderAccess::load_acquire(&_sampling_rate); 75 } 76 77 bool sampling_collector_present() const; 78 bool remove_sampling_collector(); 79 bool add_sampling_collector(); 80 }; 81 82 #endif // SHARE_RUNTIME_THREADHEAPSAMPLER_HPP