1/*
2 * Copyright (C) 2010 Apple Inc. All rights reserved.
3 *
4 * Redistribution and use in source and binary forms, with or without
5 * modification, are permitted provided that the following conditions
6 * are met:
7 * 1. Redistributions of source code must retain the above copyright
8 *    notice, this list of conditions and the following disclaimer.
9 * 2. Redistributions in binary form must reproduce the above copyright
10 *    notice, this list of conditions and the following disclaimer in the
11 *    documentation and/or other materials provided with the distribution.
12 *
13 * THIS SOFTWARE IS PROVIDED BY APPLE INC. AND ITS CONTRIBUTORS ``AS IS''
14 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
15 * THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
16 * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL APPLE INC. OR ITS CONTRIBUTORS
17 * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
18 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
19 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
20 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
21 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
22 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF
23 * THE POSSIBILITY OF SUCH DAMAGE.
24 */
25
26#include "config.h"
27#include "VisitedLinkProvider.h"
28
29#include "SharedMemory.h"
30#include "VisitedLinkTable.h"
31#include "WebContext.h"
32#include "WebProcessMessages.h"
33
34using namespace WebCore;
35
36namespace WebKit {
37
38static const int VisitedLinkTableMaxLoad = 2;
39
40VisitedLinkProvider::VisitedLinkProvider(WebContext* context)
41    : m_context(context)
42    , m_visitedLinksPopulated(false)
43    , m_webProcessHasVisitedLinkState(false)
44    , m_keyCount(0)
45    , m_tableSize(0)
46    , m_pendingVisitedLinksTimer(RunLoop::main(), this, &VisitedLinkProvider::pendingVisitedLinksTimerFired)
47{
48}
49
50void VisitedLinkProvider::processDidFinishLaunching()
51{
52    m_webProcessHasVisitedLinkState = false;
53
54    if (m_keyCount)
55        m_pendingVisitedLinksTimer.startOneShot(0);
56
57    if (m_visitedLinksPopulated)
58        return;
59
60    m_context->populateVisitedLinks();
61
62    m_visitedLinksPopulated = true;
63}
64
65void VisitedLinkProvider::addVisitedLink(LinkHash linkHash)
66{
67    m_pendingVisitedLinks.add(linkHash);
68
69    if (!m_pendingVisitedLinksTimer.isActive())
70        m_pendingVisitedLinksTimer.startOneShot(0);
71}
72
73void VisitedLinkProvider::processDidClose()
74{
75    m_pendingVisitedLinksTimer.stop();
76}
77
78static unsigned nextPowerOf2(unsigned v)
79{
80    // Taken from http://www.cs.utk.edu/~vose/c-stuff/bithacks.html
81    // Devised by Sean Anderson, Sepember 14, 2001
82
83    v--;
84    v |= v >> 1;
85    v |= v >> 2;
86    v |= v >> 4;
87    v |= v >> 8;
88    v |= v >> 16;
89    v++;
90
91    return v;
92}
93
94static unsigned tableSizeForKeyCount(unsigned keyCount)
95{
96    // We want the table to be at least half empty.
97    unsigned tableSize = nextPowerOf2(keyCount * VisitedLinkTableMaxLoad);
98
99    // Ensure that the table size is at least the size of a page.
100    size_t minimumTableSize = SharedMemory::systemPageSize() / sizeof(LinkHash);
101    if (tableSize < minimumTableSize)
102        return minimumTableSize;
103
104    return tableSize;
105}
106
107void VisitedLinkProvider::pendingVisitedLinksTimerFired()
108{
109    Vector<WebCore::LinkHash> pendingVisitedLinks;
110    copyToVector(m_pendingVisitedLinks, pendingVisitedLinks);
111    m_pendingVisitedLinks.clear();
112
113    unsigned currentTableSize = m_tableSize;
114    unsigned newTableSize = tableSizeForKeyCount(m_keyCount + pendingVisitedLinks.size());
115
116    // Links that were added.
117    Vector<WebCore::LinkHash> addedVisitedLinks;
118
119    if (currentTableSize != newTableSize) {
120        // Create a new table.
121        RefPtr<SharedMemory> newTableMemory = SharedMemory::create(newTableSize * sizeof(LinkHash));
122
123        // We failed to create the shared memory.
124        if (!newTableMemory)
125            return;
126
127        memset(newTableMemory->data(), 0, newTableMemory->size());
128
129        RefPtr<SharedMemory> currentTableMemory = m_table.sharedMemory();
130
131        m_table.setSharedMemory(newTableMemory);
132        m_tableSize = newTableSize;
133
134        if (currentTableMemory) {
135            ASSERT(currentTableMemory->size() == currentTableSize * sizeof(LinkHash));
136
137            // Go through the current hash table and re-add all entries to the new hash table.
138            const LinkHash* currentLinkHashes = static_cast<const LinkHash*>(currentTableMemory->data());
139            for (unsigned i = 0; i < currentTableSize; ++i) {
140                LinkHash linkHash = currentLinkHashes[i];
141
142                if (!linkHash)
143                    continue;
144
145                // It should always be possible to add the link hash to a new table.
146                if (!m_table.addLinkHash(linkHash))
147                    ASSERT_NOT_REACHED();
148            }
149        }
150    }
151
152    for (size_t i = 0; i < pendingVisitedLinks.size(); ++i) {
153        if (m_table.addLinkHash(pendingVisitedLinks[i]))
154            addedVisitedLinks.append(pendingVisitedLinks[i]);
155    }
156
157    m_keyCount += pendingVisitedLinks.size();
158
159    if (!m_webProcessHasVisitedLinkState || currentTableSize != newTableSize) {
160        // Send the new visited link table.
161
162        SharedMemory::Handle handle;
163        if (!m_table.sharedMemory()->createHandle(handle, SharedMemory::ReadOnly))
164            return;
165
166        // FIXME (Multi-WebProcess): Encoding a handle will null it out so we need to create a new
167        // handle for every process. Maybe the ArgumentEncoder should handle this.
168        m_context->sendToAllProcesses(Messages::WebProcess::SetVisitedLinkTable(handle));
169    }
170
171    // We now need to let the web process know that we've added links.
172    if (m_webProcessHasVisitedLinkState && addedVisitedLinks.size() <= 20) {
173        m_context->sendToAllProcesses(Messages::WebProcess::VisitedLinkStateChanged(addedVisitedLinks));
174        return;
175    }
176
177    // Just recalculate all the visited links.
178    m_context->sendToAllProcesses(Messages::WebProcess::AllVisitedLinkStateChanged());
179    m_webProcessHasVisitedLinkState = true;
180}
181
182} // namespace WebKit
183