1 /* 2 * Copyright (c) 2017, 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 #ifndef SHARE_VM_CLASSFILE_PROTECTIONDOMAINCACHE_HPP 26 #define SHARE_VM_CLASSFILE_PROTECTIONDOMAINCACHE_HPP 27 28 #include "oops/oop.hpp" 29 #include "memory/iterator.hpp" 30 #include "utilities/hashtable.hpp" 31 32 // This class caches the approved protection domains that can access loaded classes. 33 // Dictionary entry pd_set point to entries in this hashtable. Please refer 34 // to dictionary.hpp pd_set for more information about how protection domain entries 35 // are used. 36 // This table is walked during GC, rather than the class loader data graph dictionaries. 37 class ProtectionDomainCacheEntry : public HashtableEntry<oop, mtClass> { 38 friend class VMStructs; 39 public: 40 oop object(); 41 oop object_no_keepalive(); 42 43 ProtectionDomainCacheEntry* next() { 44 return (ProtectionDomainCacheEntry*)HashtableEntry<oop, mtClass>::next(); 45 } 46 47 ProtectionDomainCacheEntry** next_addr() { 48 return (ProtectionDomainCacheEntry**)HashtableEntry<oop, mtClass>::next_addr(); 49 } 50 51 void oops_do(OopClosure* f) { 52 f->do_oop(literal_addr()); 53 } 54 55 void verify(); 56 }; 57 58 // The ProtectionDomainCacheTable contains all protection domain oops. The 59 // dictionary entries reference its entries instead of having references to oops 60 // directly. 61 // This is used to speed up system dictionary iteration: the oops in the 62 // protection domain are the only ones referring the Java heap. So when there is 63 // need to update these, instead of going over every entry of the system dictionary, 64 // we only need to iterate over this set. 65 // The amount of different protection domains used is typically magnitudes smaller 66 // than the number of system dictionary entries (loaded classes). 67 class ProtectionDomainCacheTable : public Hashtable<oop, mtClass> { 68 friend class VMStructs; 69 private: 70 ProtectionDomainCacheEntry* bucket(int i) const { 71 return (ProtectionDomainCacheEntry*) Hashtable<oop, mtClass>::bucket(i); 72 } 73 74 // The following method is not MT-safe and must be done under lock. 75 ProtectionDomainCacheEntry** bucket_addr(int i) { 76 return (ProtectionDomainCacheEntry**) Hashtable<oop, mtClass>::bucket_addr(i); 77 } 78 79 ProtectionDomainCacheEntry* new_entry(unsigned int hash, Handle protection_domain) { 80 ProtectionDomainCacheEntry* entry = (ProtectionDomainCacheEntry*) Hashtable<oop, mtClass>::new_entry(hash, protection_domain()); 81 return entry; 82 } 83 84 static unsigned int compute_hash(Handle protection_domain); 85 86 int index_for(Handle protection_domain); 87 ProtectionDomainCacheEntry* add_entry(int index, unsigned int hash, Handle protection_domain); 88 ProtectionDomainCacheEntry* find_entry(int index, Handle protection_domain); 89 90 public: 91 ProtectionDomainCacheTable(int table_size); 92 ProtectionDomainCacheEntry* get(Handle protection_domain); 93 94 void unlink(BoolObjectClosure* cl); 95 96 // GC support 97 void oops_do(OopClosure* f); 98 99 void print_on(outputStream* st) const; 100 void verify(); 101 }; 102 103 104 class ProtectionDomainEntry :public CHeapObj<mtClass> { 105 friend class VMStructs; 106 public: 107 ProtectionDomainEntry* _next; 108 ProtectionDomainCacheEntry* _pd_cache; 109 110 ProtectionDomainEntry(ProtectionDomainCacheEntry* pd_cache, ProtectionDomainEntry* next) { 111 _pd_cache = pd_cache; 112 _next = next; 113 } 114 115 ProtectionDomainEntry* next() { return _next; } 116 oop object(); 117 oop object_no_keepalive(); 118 }; 119 #endif // SHARE_VM_CLASSFILE_PROTECTIONDOMAINCACHE_HPP