1 /* 2 * Copyright (c) 1997, 2010, Oracle 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 // An NmethodSweeper is an incremental cleaner for: 26 // - cleanup inline caches 27 // - reclamation of unreferences zombie nmethods 28 // 29 30 class NMethodSweeper : public AllStatic { 31 static long _traversals; // Stack traversal count 32 static nmethod* _current; // Current nmethod 33 static int _seen; // Nof. nmethod we have currently processed in current pass of CodeCache 34 35 static volatile int _invocations; // No. of invocations left until we are completed with this pass 36 static volatile int _sweep_started; // Flag to control conc sweeper 37 38 static bool _rescan; // Indicates that we should do a full rescan of the 39 // of the code cache looking for work to do. 40 static bool _do_sweep; // Flag to skip the conc sweep if no stack scan happened 41 static int _locked_seen; // Number of locked nmethods encountered during the scan 42 static int _not_entrant_seen_on_stack; // Number of not entrant nmethod were are still on stack 43 44 static bool _was_full; // remember if we did emergency unloading 45 static jint _advise_to_sweep; // flag to indicate code cache getting full 46 static jlong _last_was_full; // timestamp of last emergency unloading 47 static uint _highest_marked; // highest compile id dumped at last emergency unloading 48 static long _was_full_traversal; // trav number at last emergency unloading 49 50 static void process_nmethod(nmethod *nm); 51 52 static void log_sweep(const char* msg, const char* format = NULL, ...); 53 54 public: 55 static long traversal_count() { return _traversals; } 56 57 static void scan_stacks(); // Invoked at the end of each safepoint 58 static void sweep_code_cache(); // Concurrent part of sweep job 59 static void possibly_sweep(); // Compiler threads call this to sweep 60 61 static void notify(nmethod* nm) { 62 // Perform a full scan of the code cache from the beginning. No 63 // need to synchronize the setting of this flag since it only 64 // changes to false at safepoint so we can never overwrite it with false. 65 _rescan = true; 66 } 67 68 static void handle_full_code_cache(bool is_full); // Called by compilers who fail to allocate 69 static void speculative_disconnect_nmethods(bool was_full); // Called by vm op to deal with alloc failure 70 71 static void set_was_full(bool state) { _was_full = state; } 72 static bool was_full() { return _was_full; } 73 };