1 /*
   2  * Copyright (c) 2015, 2018, 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_COMPACTHASHTABLE_INLINE_HPP
  26 #define SHARE_VM_CLASSFILE_COMPACTHASHTABLE_INLINE_HPP
  27 
  28 #include "classfile/compactHashtable.hpp"
  29 #include "classfile/javaClasses.hpp"
  30 #include "memory/allocation.inline.hpp"
  31 #include "memory/filemap.hpp"
  32 #include "memory/heapShared.inline.hpp"
  33 #include "oops/oop.hpp"
  34 
  35 template <class T, class N>
  36 inline Symbol* CompactHashtable<T, N>::decode_entry(CompactHashtable<Symbol*, char>* const t,
  37                                                     u4 offset, const char* name, int len) {
  38   Symbol* sym = (Symbol*)(_base_address + offset);
  39   if (sym->equals(name, len)) {
  40     assert(sym->refcount() == PERM_REFCOUNT, "must be shared");
  41     return sym;
  42   }
  43 
  44   return NULL;
  45 }
  46 
  47 template <class T, class N>
  48 inline oop CompactHashtable<T, N>::decode_entry(CompactHashtable<oop, char>* const t,
  49                                                 u4 offset, const char* name, int len) {
  50   narrowOop v = (narrowOop)offset;
  51   oop string = HeapShared::decode_not_null(v);
  52   if (java_lang_String::equals(string, (jchar*)name, len)) {
  53     return string;
  54   }
  55 
  56   return NULL;
  57 }
  58 
  59 template <class T, class N>
  60 inline T CompactHashtable<T,N>::lookup(const N* name, unsigned int hash, int len) {
  61   if (_entry_count > 0) {
  62     int index = hash % _bucket_count;
  63     u4 bucket_info = _buckets[index];
  64     u4 bucket_offset = BUCKET_OFFSET(bucket_info);
  65     int bucket_type = BUCKET_TYPE(bucket_info);
  66     u4* entry = _entries + bucket_offset;
  67 
  68     if (bucket_type == VALUE_ONLY_BUCKET_TYPE) {
  69       T res = decode_entry(this, entry[0], name, len);
  70       if (res != NULL) {
  71         return res;
  72       }
  73     } else {
  74       // This is a regular bucket, which has more than one
  75       // entries. Each entry is a pair of entry (hash, offset).
  76       // Seek until the end of the bucket.
  77       u4* entry_max = _entries + BUCKET_OFFSET(_buckets[index + 1]);
  78       while (entry < entry_max) {
  79         unsigned int h = (unsigned int)(entry[0]);
  80         if (h == hash) {
  81           T res = decode_entry(this, entry[1], name, len);
  82           if (res != NULL) {
  83             return res;
  84           }
  85         }
  86         entry += 2;
  87       }
  88     }
  89   }
  90   return NULL;
  91 }
  92 
  93 #endif // SHARE_VM_CLASSFILE_COMPACTHASHTABLE_INLINE_HPP