1 /*
   2  * Copyright (c) 1996, 2013, 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.  Oracle designates this
   8  * particular file as subject to the "Classpath" exception as provided
   9  * by Oracle in the LICENSE file that accompanied this code.
  10  *
  11  * This code is distributed in the hope that it will be useful, but WITHOUT
  12  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  13  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  14  * version 2 for more details (a copy is included in the LICENSE file that
  15  * accompanied this code).
  16  *
  17  * You should have received a copy of the GNU General Public License version
  18  * 2 along with this work; if not, write to the Free Software Foundation,
  19  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  20  *
  21  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
  22  * or visit www.oracle.com if you need additional information or have any
  23  * questions.
  24  */
  25 
  26 #include "CmdIDList.h"
  27 
  28 // How much space to allocate initially
  29 static const UINT ARRAY_INITIAL_SIZE = 1024;
  30 
  31 // Array expansion increment when need more free space
  32 static const UINT ARRAY_SIZE_INCREMENT = 1024;
  33 
  34 // It seems that Win95 can not handle ids greater than 2**16
  35 static const UINT ARRAY_MAXIMUM_SIZE = 32768;
  36 
  37 
  38 AwtCmdIDList::AwtCmdIDList()
  39 {
  40     m_capacity = ARRAY_INITIAL_SIZE;
  41     m_first_free = -1;
  42     m_array = (CmdIDEntry *)SAFE_SIZE_ARRAY_ALLOC(safe_Malloc, m_capacity, sizeof(AwtObject*));
  43     BuildFreeList(0);
  44 }
  45 
  46 AwtCmdIDList::~AwtCmdIDList()
  47 {
  48     free(m_array);
  49 }
  50 
  51 
  52 // Build a new free list from a newly allocated memory.  This only
  53 // happens after malloc/realloc, and new free entries are contiguous
  54 // from first_index to m_capacity-1
  55 INLINE void AwtCmdIDList::BuildFreeList(UINT first_index)
  56 {
  57     DASSERT(m_first_free == -1);
  58     for (UINT i = first_index; i < m_capacity-1; ++i)
  59         m_array[i].next_free_index = i+1;
  60     m_array[m_capacity-1].next_free_index = -1; // nil
  61     m_first_free = first_index; // head of the free list
  62 }
  63 
  64 // Assign an id to the object.  Recycle the first free entry from the
  65 // head of the free list or allocate more memory for a new free list.
  66 UINT AwtCmdIDList::Add(AwtObject* obj)
  67 {
  68     CriticalSection::Lock l(m_lock);
  69 
  70     if (m_first_free == -1) {   // out of free ids
  71         if (m_capacity == ARRAY_MAXIMUM_SIZE) {
  72             // Really bad - out of ids.  Since we hardly can have *so*
  73             // many items simultaneously in existence, we have an id
  74             // leak somewhere.
  75             DASSERT(FALSE);
  76             return 0;
  77         }
  78         else {                  // snarf a bigger arena
  79             UINT old_capacity = m_capacity; // will be the first free entry
  80             m_capacity += ARRAY_SIZE_INCREMENT;
  81             if (m_capacity > ARRAY_MAXIMUM_SIZE)
  82                 m_capacity = ARRAY_MAXIMUM_SIZE;
  83             m_array = (CmdIDEntry *)SAFE_SIZE_ARRAY_REALLOC(safe_Realloc, m_array,
  84                                         m_capacity, sizeof(CmdIDEntry*));
  85             BuildFreeList(old_capacity);
  86         }
  87     }
  88 
  89     DASSERT(m_first_free != -1);
  90     UINT newid = m_first_free;  // use the entry from the head of the list
  91     m_first_free = m_array[newid].next_free_index; // advance free pointer
  92     m_array[newid].obj = obj;
  93 
  94     return newid;
  95 }
  96 
  97 // Return the object associated with this id..
  98 AwtObject* AwtCmdIDList::Lookup(UINT id)
  99 {
 100     CriticalSection::Lock l(m_lock);
 101     DASSERT(id < m_capacity);
 102     if (m_array[id].next_free_index <= ARRAY_MAXIMUM_SIZE) {
 103         return NULL;
 104     }
 105     return m_array[id].obj;
 106 }
 107 
 108 // Return this id to the head of the free list.
 109 void AwtCmdIDList::Remove(UINT id)
 110 {
 111     CriticalSection::Lock l(m_lock);
 112     DASSERT(id < m_capacity);
 113     DASSERT(m_array[id].next_free_index > ARRAY_MAXIMUM_SIZE); // it's a pointer
 114     m_array[id].next_free_index = m_first_free;
 115     m_first_free = id;
 116 }