summaryrefslogtreecommitdiffstats
path: root/src/libs/xpcom18a4/xpcom/ds/nsFixedSizeAllocator.cpp
blob: 1b6232f99ad143935699a7130a797ab6617a98c9 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
/* ***** BEGIN LICENSE BLOCK *****
 * Version: MPL 1.1/GPL 2.0/LGPL 2.1
 *
 * The contents of this file are subject to the Mozilla Public License Version
 * 1.1 (the "License"); you may not use this file except in compliance with
 * the License. You may obtain a copy of the License at
 * http://www.mozilla.org/MPL/
 *
 * Software distributed under the License is distributed on an "AS IS" basis,
 * WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License
 * for the specific language governing rights and limitations under the
 * License.
 *
 * The Original Code is mozilla.org code.
 *
 * The Initial Developer of the Original Code is
 * Netscape Communications Corporation.
 * Portions created by the Initial Developer are Copyright (C) 1998
 * the Initial Developer. All Rights Reserved.
 *
 * Contributor(s):
 *   Chris Waterson <waterson@netscape.com
 *
 * Alternatively, the contents of this file may be used under the terms of
 * either of the GNU General Public License Version 2 or later (the "GPL"),
 * or the GNU Lesser General Public License Version 2.1 or later (the "LGPL"),
 * in which case the provisions of the GPL or the LGPL are applicable instead
 * of those above. If you wish to allow use of your version of this file only
 * under the terms of either the GPL or the LGPL, and not to allow others to
 * use your version of this file under the terms of the MPL, indicate your
 * decision by deleting the provisions above and replace them with the notice
 * and other provisions required by the GPL or the LGPL. If you do not delete
 * the provisions above, a recipient may use your version of this file under
 * the terms of any one of the MPL, the GPL or the LGPL.
 *
 * ***** END LICENSE BLOCK ***** */

/*

  Implementation for nsFixedSizeAllocator

*/

#include "nsCRT.h"
#include "nsFixedSizeAllocator.h"

nsFixedSizeAllocator::Bucket *
nsFixedSizeAllocator::AddBucket(size_t aSize)
{
    void* p;
    PL_ARENA_ALLOCATE(p, &mPool, sizeof(Bucket));
    if (! p)
        return nsnull;

    Bucket* bucket = NS_STATIC_CAST(Bucket*, p);
    bucket->mSize  = aSize;
    bucket->mFirst = nsnull;
    bucket->mNext  = mBuckets;

    mBuckets = bucket;
    return bucket;
}

nsresult
nsFixedSizeAllocator::Init(const char* aName,
                           const size_t* aBucketSizes,
                           PRInt32 aNumBuckets,
                           PRInt32 aInitialSize,
                           PRInt32 aAlign)
{
    NS_PRECONDITION(aNumBuckets > 0, "no buckets");
    if (aNumBuckets <= 0)
        return NS_ERROR_INVALID_ARG;

    // Blow away the old pool if we're being re-initialized.
    if (mBuckets)
        PL_FinishArenaPool(&mPool);

    PRInt32 bucketspace = aNumBuckets * sizeof(Bucket);
    PL_InitArenaPool(&mPool, aName, bucketspace + aInitialSize, aAlign);

    mBuckets = nsnull;
    for (PRInt32 i = 0; i < aNumBuckets; ++i)
        AddBucket(aBucketSizes[i]);

    return NS_OK;
}

nsFixedSizeAllocator::Bucket *
nsFixedSizeAllocator::FindBucket(size_t aSize)
{
    Bucket** link = &mBuckets;
    Bucket* bucket;

    while ((bucket = *link) != nsnull) {
        if (aSize == bucket->mSize) {
            // Promote to the head of the list, under the assumption
            // that we'll allocate same-sized object contemporaneously.
            *link = bucket->mNext;
            bucket->mNext = mBuckets;
            mBuckets = bucket;
            return bucket;
        }

        link = &bucket->mNext;
    }
    return nsnull;
}

void*
nsFixedSizeAllocator::Alloc(size_t aSize)
{
    Bucket* bucket = FindBucket(aSize);
    if (! bucket) {
        // Oops, we don't carry that size. Let's fix that.
        bucket = AddBucket(aSize);
        if (! bucket)
            return nsnull;
    }

    void* next;
    if (bucket->mFirst) {
        next = bucket->mFirst;
        bucket->mFirst = bucket->mFirst->mNext;
    }
    else {
        PL_ARENA_ALLOCATE(next, &mPool, aSize);
        if (!next)
            return nsnull;
    }

#ifdef DEBUG
    memset(next, 0xc8, aSize);
#endif

    return next;
}

void
nsFixedSizeAllocator::Free(void* aPtr, size_t aSize)
{
    FreeEntry* entry = NS_REINTERPRET_CAST(FreeEntry*, aPtr);
    Bucket* bucket = FindBucket(aSize);

#ifdef DEBUG
    NS_ASSERTION(bucket && bucket->mSize == aSize, "ack! corruption! bucket->mSize != aSize!");
    memset(aPtr, 0xd8, bucket->mSize);
#endif

    entry->mNext = bucket->mFirst;
    bucket->mFirst = entry;
}