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