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<title>[173080] trunk/Source/WebCore</title>
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<dt>Revision</dt> <dd><a href="http://trac.webkit.org/projects/webkit/changeset/173080">173080</a></dd>
<dt>Author</dt> <dd>psolanki@apple.com</dd>
<dt>Date</dt> <dd>2014-08-28 14:08:26 -0700 (Thu, 28 Aug 2014)</dd>
</dl>
<h3>Log Message</h3>
<pre>WebContent hangs under SharedBuffer::duplicateDataBufferIfNecessary() while browsing some websites
https://bugs.webkit.org/show_bug.cgi?id=136347
<rdar://problem/18073745>
Reviewed by Andreas Kling.
When passing data to ImageIO, we create a copy if we have to reallocate the buffer. We would
set the size of the new buffer to be the size of the SharedBuffer data. This causes memory
churn since we would create a new buffer for every data chunk we get. Fix this by at least
doubling the capacity of the buffer when we duplicate it.
* platform/SharedBuffer.cpp:
(WebCore::SharedBuffer::duplicateDataBufferIfNecessary):</pre>
<h3>Modified Paths</h3>
<ul>
<li><a href="#trunkSourceWebCoreChangeLog">trunk/Source/WebCore/ChangeLog</a></li>
<li><a href="#trunkSourceWebCoreplatformSharedBuffercpp">trunk/Source/WebCore/platform/SharedBuffer.cpp</a></li>
</ul>
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<div id="patch">
<h3>Diff</h3>
<a id="trunkSourceWebCoreChangeLog"></a>
<div class="modfile"><h4>Modified: trunk/Source/WebCore/ChangeLog (173079 => 173080)</h4>
<pre class="diff"><span>
<span class="info">--- trunk/Source/WebCore/ChangeLog 2014-08-28 21:01:25 UTC (rev 173079)
+++ trunk/Source/WebCore/ChangeLog 2014-08-28 21:08:26 UTC (rev 173080)
</span><span class="lines">@@ -1,3 +1,19 @@
</span><ins>+2014-08-28 Pratik Solanki <psolanki@apple.com>
+
+ WebContent hangs under SharedBuffer::duplicateDataBufferIfNecessary() while browsing some websites
+ https://bugs.webkit.org/show_bug.cgi?id=136347
+ <rdar://problem/18073745>
+
+ Reviewed by Andreas Kling.
+
+ When passing data to ImageIO, we create a copy if we have to reallocate the buffer. We would
+ set the size of the new buffer to be the size of the SharedBuffer data. This causes memory
+ churn since we would create a new buffer for every data chunk we get. Fix this by at least
+ doubling the capacity of the buffer when we duplicate it.
+
+ * platform/SharedBuffer.cpp:
+ (WebCore::SharedBuffer::duplicateDataBufferIfNecessary):
+
</ins><span class="cx"> 2014-08-28 Dan Bernstein <mitz@apple.com>
</span><span class="cx">
</span><span class="cx"> iOS build fix.
</span></span></pre></div>
<a id="trunkSourceWebCoreplatformSharedBuffercpp"></a>
<div class="modfile"><h4>Modified: trunk/Source/WebCore/platform/SharedBuffer.cpp (173079 => 173080)</h4>
<pre class="diff"><span>
<span class="info">--- trunk/Source/WebCore/platform/SharedBuffer.cpp 2014-08-28 21:01:25 UTC (rev 173079)
+++ trunk/Source/WebCore/platform/SharedBuffer.cpp 2014-08-28 21:08:26 UTC (rev 173080)
</span><span class="lines">@@ -27,6 +27,7 @@
</span><span class="cx"> #include "config.h"
</span><span class="cx"> #include "SharedBuffer.h"
</span><span class="cx">
</span><ins>+#include <algorithm>
</ins><span class="cx"> #include <wtf/PassOwnPtr.h>
</span><span class="cx"> #include <wtf/unicode/UTF8.h>
</span><span class="cx">
</span><span class="lines">@@ -351,11 +352,13 @@
</span><span class="cx">
</span><span class="cx"> void SharedBuffer::duplicateDataBufferIfNecessary() const
</span><span class="cx"> {
</span><del>- if (m_buffer->hasOneRef() || m_size <= m_buffer->data.capacity())
</del><ins>+ size_t currentCapacity = m_buffer->data.capacity();
+ if (m_buffer->hasOneRef() || m_size <= currentCapacity)
</ins><span class="cx"> return;
</span><span class="cx">
</span><ins>+ size_t newCapacity = std::max(static_cast<size_t>(m_size), currentCapacity * 2);
</ins><span class="cx"> RefPtr<DataBuffer> newBuffer = adoptRef(new DataBuffer);
</span><del>- newBuffer->data.reserveInitialCapacity(m_size);
</del><ins>+ newBuffer->data.reserveInitialCapacity(newCapacity);
</ins><span class="cx"> newBuffer->data = m_buffer->data;
</span><span class="cx"> m_buffer = newBuffer.release();
</span><span class="cx"> }
</span></span></pre>
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