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 30 class ThreadHeapSampler { 31 private: 32 size_t _bytes_until_sample; 33 Thread* _thread; 34 // Cheap random number generator 35 static uint64_t _rnd; 36 37 void pick_next_geometric_sample(); 38 void pick_next_sample(size_t overflowed_bytes = 0); 39 static int _enabled; 40 static int _sampling_rate; 41 42 void init_log_table(); 43 44 public: 45 ThreadHeapSampler() : _bytes_until_sample(0), _thread(NULL) { 46 _rnd = static_cast<uint32_t>(reinterpret_cast<uintptr_t>(this)); 47 if (_rnd == 0) { 48 _rnd = 1; 49 } 50 init_log_table(); 51 } 52 53 void set_thread(Thread* t) { _thread = t; } 54 55 size_t bytes_until_sample() { return _bytes_until_sample; } 56 void set_bytes_until_sample(size_t bytes) { _bytes_until_sample = bytes; } 57 58 void check_for_sampling(HeapWord* obj, size_t size_in_bytes, size_t bytes_allocated_before = 0); 59 60 static int enabled() { return OrderAccess::load_acquire(&_enabled); } 61 static void enable() { OrderAccess::release_store(&_enabled, 1); } 62 static void disable() { OrderAccess::release_store(&_enabled, 0); } 63 static void set_tlab_heap_sampling(int sampling_rate); 64 }; 65 66 #endif // SHARE_RUNTIME_THREADHEAPSAMPLER_HPP