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 
  65 jboolean AwtCmdIDList::isFreeIDAvailable() {
  66     CriticalSection::Lock l(m_lock);
  67 
  68     if (m_first_free == -1) {   // out of free ids
  69         if (m_capacity == ARRAY_MAXIMUM_SIZE) {
  70             return JNI_FALSE;
  71         }
  72     }
  73     return JNI_TRUE;
  74 }
  75 
  76 // Assign an id to the object.  Recycle the first free entry from the
  77 // head of the free list or allocate more memory for a new free list.
  78 UINT AwtCmdIDList::Add(AwtObject* obj)
  79 {
  80     CriticalSection::Lock l(m_lock);
  81     if (!isFreeIDAvailable()) {
  82         throw std::bad_alloc(); // fatal error
  83     }
  84 
  85     if (m_first_free == -1) {   // out of free ids
  86         // snarf a bigger arena
  87         UINT old_capacity = m_capacity; // will be the first free entry
  88         m_capacity += ARRAY_SIZE_INCREMENT;
  89         if (m_capacity > ARRAY_MAXIMUM_SIZE)
  90             m_capacity = ARRAY_MAXIMUM_SIZE;
  91         m_array = (CmdIDEntry *)SAFE_SIZE_ARRAY_REALLOC(safe_Realloc, m_array,
  92                                     m_capacity, sizeof(CmdIDEntry*));
  93         BuildFreeList(old_capacity);
  94     }
  95 
  96     DASSERT(m_first_free != -1);
  97     UINT newid = m_first_free;  // use the entry from the head of the list
  98     m_first_free = m_array[newid].next_free_index; // advance free pointer
  99     m_array[newid].obj = obj;
 100 
 101     return newid;
 102 }
 103 
 104 // Return the object associated with this id..
 105 AwtObject* AwtCmdIDList::Lookup(UINT id)
 106 {
 107     CriticalSection::Lock l(m_lock);
 108     DASSERT(id < m_capacity);
 109     if (m_array[id].next_free_index <= ARRAY_MAXIMUM_SIZE) {
 110         return NULL;
 111     }
 112     return m_array[id].obj;
 113 }
 114 
 115 // Return this id to the head of the free list.
 116 void AwtCmdIDList::Remove(UINT id)
 117 {
 118     CriticalSection::Lock l(m_lock);
 119     DASSERT(id < m_capacity);
 120     DASSERT(m_array[id].next_free_index > ARRAY_MAXIMUM_SIZE); // it's a pointer
 121     m_array[id].next_free_index = m_first_free;
 122     m_first_free = id;
 123 }