1 /*
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   3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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   6  * under the terms of the GNU General Public License version 2 only, as
   7  * published by the Free Software Foundation.
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  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
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  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
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  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