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<dt>Revision</dt> <dd><a href="http://trac.webkit.org/projects/webkit/changeset/179850">179850</a></dd>
<dt>Author</dt> <dd>timothy_horton@apple.com</dd>
<dt>Date</dt> <dd>2015-02-09 15:39:41 -0800 (Mon, 09 Feb 2015)</dd>
</dl>
<h3>Log Message</h3>
<pre>Avoid using a HashMap for DisplayRefreshMonitorManager, which rarely has more than one item
https://bugs.webkit.org/show_bug.cgi?id=141353
Reviewed by Anders Carlsson.
No new tests, because there's no behavior change.
* platform/graphics/DisplayRefreshMonitorManager.cpp:
(WebCore::DisplayRefreshMonitorManager::ensureMonitorForClient):
(WebCore::DisplayRefreshMonitorManager::unregisterClient):
(WebCore::DisplayRefreshMonitorManager::displayDidRefresh):
* platform/graphics/DisplayRefreshMonitorManager.h:
Use a Vector of RefPtr<DisplayRefreshMonitor> instead of a HashMap
from uint64_t to RefPtr<DisplayRefreshMonitor>. There's usually only one
display, so there's usually only one DisplayRefreshMonitor. Linear search
on the Vector will be faster than the hash lookup in all conceivable cases.
This also avoids the situation mentioned in the comments in DisplayRefreshMonitorManager.h
where we don't know enough about PlatformDisplayID to safely hash it.</pre>
<h3>Modified Paths</h3>
<ul>
<li><a href="#trunkSourceWebCoreChangeLog">trunk/Source/WebCore/ChangeLog</a></li>
<li><a href="#trunkSourceWebCoreplatformgraphicsDisplayRefreshMonitorManagercpp">trunk/Source/WebCore/platform/graphics/DisplayRefreshMonitorManager.cpp</a></li>
<li><a href="#trunkSourceWebCoreplatformgraphicsDisplayRefreshMonitorManagerh">trunk/Source/WebCore/platform/graphics/DisplayRefreshMonitorManager.h</a></li>
</ul>
</div>
<div id="patch">
<h3>Diff</h3>
<a id="trunkSourceWebCoreChangeLog"></a>
<div class="modfile"><h4>Modified: trunk/Source/WebCore/ChangeLog (179849 => 179850)</h4>
<pre class="diff"><span>
<span class="info">--- trunk/Source/WebCore/ChangeLog 2015-02-09 23:26:22 UTC (rev 179849)
+++ trunk/Source/WebCore/ChangeLog 2015-02-09 23:39:41 UTC (rev 179850)
</span><span class="lines">@@ -1,3 +1,24 @@
</span><ins>+2015-02-09 Timothy Horton <timothy_horton@apple.com>
+
+ Avoid using a HashMap for DisplayRefreshMonitorManager, which rarely has more than one item
+ https://bugs.webkit.org/show_bug.cgi?id=141353
+
+ Reviewed by Anders Carlsson.
+
+ No new tests, because there's no behavior change.
+
+ * platform/graphics/DisplayRefreshMonitorManager.cpp:
+ (WebCore::DisplayRefreshMonitorManager::ensureMonitorForClient):
+ (WebCore::DisplayRefreshMonitorManager::unregisterClient):
+ (WebCore::DisplayRefreshMonitorManager::displayDidRefresh):
+ * platform/graphics/DisplayRefreshMonitorManager.h:
+ Use a Vector of RefPtr<DisplayRefreshMonitor> instead of a HashMap
+ from uint64_t to RefPtr<DisplayRefreshMonitor>. There's usually only one
+ display, so there's usually only one DisplayRefreshMonitor. Linear search
+ on the Vector will be faster than the hash lookup in all conceivable cases.
+ This also avoids the situation mentioned in the comments in DisplayRefreshMonitorManager.h
+ where we don't know enough about PlatformDisplayID to safely hash it.
+
</ins><span class="cx"> 2015-02-09 Jer Noble <jer.noble@apple.com>
</span><span class="cx">
</span><span class="cx"> [Mac] Disable the currentTime estimation code in HTMLMediaElement for Yosemite+
</span></span></pre></div>
<a id="trunkSourceWebCoreplatformgraphicsDisplayRefreshMonitorManagercpp"></a>
<div class="modfile"><h4>Modified: trunk/Source/WebCore/platform/graphics/DisplayRefreshMonitorManager.cpp (179849 => 179850)</h4>
<pre class="diff"><span>
<span class="info">--- trunk/Source/WebCore/platform/graphics/DisplayRefreshMonitorManager.cpp 2015-02-09 23:26:22 UTC (rev 179849)
+++ trunk/Source/WebCore/platform/graphics/DisplayRefreshMonitorManager.cpp 2015-02-09 23:39:41 UTC (rev 179850)
</span><span class="lines">@@ -46,16 +46,19 @@
</span><span class="cx">
</span><span class="cx"> DisplayRefreshMonitor* DisplayRefreshMonitorManager::ensureMonitorForClient(DisplayRefreshMonitorClient* client)
</span><span class="cx"> {
</span><del>- DisplayRefreshMonitorMap::iterator it = m_monitors.find(client->displayID());
- if (it == m_monitors.end()) {
- RefPtr<DisplayRefreshMonitor> monitor = DisplayRefreshMonitor::create(client);
</del><ins>+ PlatformDisplayID clientDisplayID = client->displayID();
+ for (const RefPtr<DisplayRefreshMonitor>& monitor : m_monitors) {
+ if (monitor->displayID() != clientDisplayID)
+ continue;
</ins><span class="cx"> monitor->addClient(client);
</span><del>- DisplayRefreshMonitor* result = monitor.get();
- m_monitors.add(client->displayID(), monitor.release());
- return result;
</del><ins>+ return monitor.get();
</ins><span class="cx"> }
</span><del>- it->value->addClient(client);
- return it->value.get();
</del><ins>+
+ RefPtr<DisplayRefreshMonitor> monitor = DisplayRefreshMonitor::create(client);
+ monitor->addClient(client);
+ DisplayRefreshMonitor* result = monitor.get();
+ m_monitors.append(monitor.release());
+ return result;
</ins><span class="cx"> }
</span><span class="cx">
</span><span class="cx"> void DisplayRefreshMonitorManager::registerClient(DisplayRefreshMonitorClient* client)
</span><span class="lines">@@ -71,14 +74,16 @@
</span><span class="cx"> if (!client->hasDisplayID())
</span><span class="cx"> return;
</span><span class="cx">
</span><del>- DisplayRefreshMonitorMap::iterator it = m_monitors.find(client->displayID());
- if (it == m_monitors.end())
</del><ins>+ PlatformDisplayID clientDisplayID = client->displayID();
+ for (size_t i = 0; i < m_monitors.size(); ++i) {
+ RefPtr<DisplayRefreshMonitor> monitor = m_monitors[i];
+ if (monitor->displayID() != clientDisplayID)
+ continue;
+ if (monitor->removeClient(client)) {
+ if (!monitor->hasClients())
+ m_monitors.remove(i);
+ }
</ins><span class="cx"> return;
</span><del>-
- DisplayRefreshMonitor* monitor = it->value.get();
- if (monitor->removeClient(client)) {
- if (!monitor->hasClients())
- m_monitors.remove(it);
</del><span class="cx"> }
</span><span class="cx"> }
</span><span class="cx">
</span><span class="lines">@@ -95,10 +100,12 @@
</span><span class="cx">
</span><span class="cx"> void DisplayRefreshMonitorManager::displayDidRefresh(DisplayRefreshMonitor* monitor)
</span><span class="cx"> {
</span><del>- if (monitor->shouldBeTerminated()) {
- ASSERT(m_monitors.contains(monitor->displayID()));
- m_monitors.remove(monitor->displayID());
- }
</del><ins>+ if (!monitor->shouldBeTerminated())
+ return;
+
+ size_t monitorIndex = m_monitors.find(monitor);
+ ASSERT(monitorIndex != notFound);
+ m_monitors.remove(monitorIndex);
</ins><span class="cx"> }
</span><span class="cx">
</span><span class="cx"> void DisplayRefreshMonitorManager::windowScreenDidChange(PlatformDisplayID displayID, DisplayRefreshMonitorClient* client)
</span></span></pre></div>
<a id="trunkSourceWebCoreplatformgraphicsDisplayRefreshMonitorManagerh"></a>
<div class="modfile"><h4>Modified: trunk/Source/WebCore/platform/graphics/DisplayRefreshMonitorManager.h (179849 => 179850)</h4>
<pre class="diff"><span>
<span class="info">--- trunk/Source/WebCore/platform/graphics/DisplayRefreshMonitorManager.h 2015-02-09 23:26:22 UTC (rev 179849)
+++ trunk/Source/WebCore/platform/graphics/DisplayRefreshMonitorManager.h 2015-02-09 23:39:41 UTC (rev 179850)
</span><span class="lines">@@ -30,9 +30,9 @@
</span><span class="cx">
</span><span class="cx"> #include "DisplayRefreshMonitor.h"
</span><span class="cx"> #include "PlatformScreen.h"
</span><del>-#include <wtf/HashMap.h>
</del><span class="cx"> #include <wtf/NeverDestroyed.h>
</span><span class="cx"> #include <wtf/RefPtr.h>
</span><ins>+#include <wtf/Vector.h>
</ins><span class="cx">
</span><span class="cx"> namespace WebCore {
</span><span class="cx">
</span><span class="lines">@@ -56,11 +56,7 @@
</span><span class="cx">
</span><span class="cx"> DisplayRefreshMonitor* ensureMonitorForClient(DisplayRefreshMonitorClient*);
</span><span class="cx">
</span><del>- // We know nothing about the values of PlatformDisplayIDs, so use UnsignedWithZeroKeyHashTraits.
- // FIXME: Since we know nothing about these values, this is not sufficient.
- // Even with UnsignedWithZeroKeyHashTraits, there are still two special values used for empty and deleted hash table slots.
- typedef HashMap<uint64_t, RefPtr<DisplayRefreshMonitor>, WTF::IntHash<uint64_t>, WTF::UnsignedWithZeroKeyHashTraits<uint64_t>> DisplayRefreshMonitorMap;
- DisplayRefreshMonitorMap m_monitors;
</del><ins>+ Vector<RefPtr<DisplayRefreshMonitor>> m_monitors;
</ins><span class="cx"> };
</span><span class="cx">
</span><span class="cx"> }
</span></span></pre>
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