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 // Cheap random number generator 34 static uint64_t _rnd; 35 36 void pick_next_geometric_sample(); 37 void pick_next_sample(size_t overflowed_bytes = 0); 38 static int _enabled; 39 static int _sampling_rate; 40 41 // Used for assertion mode to determine if there is a path to a TLAB slow path 42 // without a collector present. 43 size_t _collectors_present; 44 45 static void init_log_table(); 46 47 public: 48 ThreadHeapSampler() : _bytes_until_sample(0) { 49 _rnd = static_cast<uint32_t>(reinterpret_cast<uintptr_t>(this)); 50 if (_rnd == 0) { 51 _rnd = 1; 52 } 53 54 _collectors_present = 0; 55 } 56 57 size_t bytes_until_sample() { return _bytes_until_sample; } 58 void set_bytes_until_sample(size_t bytes) { _bytes_until_sample = bytes; } 59 60 void check_for_sampling(HeapWord* obj, size_t size_in_bytes, size_t bytes_allocated_before = 0); 61 62 static int enabled(); 63 static void enable(); 64 static void disable(); 65 66 static void set_sampling_rate(int sampling_rate); 67 static int get_sampling_rate(); 68 69 bool sampling_collector_present() const; 70 bool remove_sampling_collector(); 71 bool add_sampling_collector(); 72 }; 73 74 #endif // SHARE_RUNTIME_THREADHEAPSAMPLER_HPP