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<dt>Revision</dt> <dd><a href="http://trac.webkit.org/projects/webkit/changeset/201252">201252</a></dd>
<dt>Author</dt> <dd>bshafiei@apple.com</dd>
<dt>Date</dt> <dd>2016-05-22 09:51:47 -0700 (Sun, 22 May 2016)</dd>
</dl>
<h3>Log Message</h3>
<pre>Merge <a href="http://trac.webkit.org/projects/webkit/changeset/201246">r201246</a>. rdar://problem/22524550</pre>
<h3>Modified Paths</h3>
<ul>
<li><a href="#branchessafari602132branchSourceWebKit2ChangeLog">branches/safari-602.1.32-branch/Source/WebKit2/ChangeLog</a></li>
<li><a href="#branchessafari602132branchSourceWebKit2PlatformIPCConnectioncpp">branches/safari-602.1.32-branch/Source/WebKit2/Platform/IPC/Connection.cpp</a></li>
<li><a href="#branchessafari602132branchSourceWebKit2UIProcessAPICocoaWKWebViewmm">branches/safari-602.1.32-branch/Source/WebKit2/UIProcess/API/Cocoa/WKWebView.mm</a></li>
</ul>
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<div id="patch">
<h3>Diff</h3>
<a id="branchessafari602132branchSourceWebKit2ChangeLog"></a>
<div class="modfile"><h4>Modified: branches/safari-602.1.32-branch/Source/WebKit2/ChangeLog (201251 => 201252)</h4>
<pre class="diff"><span>
<span class="info">--- branches/safari-602.1.32-branch/Source/WebKit2/ChangeLog 2016-05-22 16:51:44 UTC (rev 201251)
+++ branches/safari-602.1.32-branch/Source/WebKit2/ChangeLog 2016-05-22 16:51:47 UTC (rev 201252)
</span><span class="lines">@@ -1,3 +1,43 @@
</span><ins>+2016-05-22 Babak Shafiei <bshafiei@apple.com>
+
+ Merge r201246. rdar://problem/22524550
+
+ 2016-05-21 Andy Estes <aestes@apple.com>
+
+ REGRESSION (r188642): All pages are blank when printing a webpage in iOS Safari
+ https://bugs.webkit.org/show_bug.cgi?id=157924
+ rdar://problem/22524550
+
+ Reviewed by Sam Weinig.
+
+ When UIPrintInteractionController asks WKWebView to print a webpage, it does so in several phases. First we're
+ asked to compute the page count, followed later by a series of messages asking us to draw each page into a
+ provided CGContext.
+
+ When asked for the page count, we send a message to the Web process instructing it to compute and
+ return the page count synchronously and then immediately start drawing the page for printing. If the drawing has
+ finished by the time we're asked to print the first page, then we can do so without waiting. But if it hasn't
+ then we block by calling Connection::waitForMessage(), passing std::chromo::milliseconds::max() as the relative
+ timeout.
+
+ Prior to r188642, Connection::waitForMessage() called std::condition_variable::wait_for(), which takes a
+ relative timeout value. r188642 replaced this with WTF::Condition::waitUntil(), which takes an absolute timeout
+ instead. To convert from relative to absolute, this line was added to Connection::waitForMessage():
+
+ Condition::Clock::time_point absoluteTimeout = Condition::Clock::now() + timeout;
+
+ std::chrono will convert both operands to a common duration type before performing the addition. When timeout
+ equals something very large, like milliseconds::max(), this conversion results in signed integer overflow,
+ giving absoluteTimeout a value less than Clock::now() and making waitForMessage time out immediately.
+
+ To fix this, compute how many milliseconds remain on our clock, and add the smaller of that and the timeout
+ value to Clock::now() to arrive at an absolute timeout.
+
+ * Platform/IPC/Connection.cpp:
+ (IPC::Connection::waitForMessage):
+ * UIProcess/API/Cocoa/WKWebView.mm:
+ (-[WKWebView _printedDocument]): Removed an unnecessary nanoseconds-to-milliseconds conversion.
+
</ins><span class="cx"> 2016-05-20 Babak Shafiei <bshafiei@apple.com>
</span><span class="cx">
</span><span class="cx"> Merge r201227. rdar://problem/24577706
</span></span></pre></div>
<a id="branchessafari602132branchSourceWebKit2PlatformIPCConnectioncpp"></a>
<div class="modfile"><h4>Modified: branches/safari-602.1.32-branch/Source/WebKit2/Platform/IPC/Connection.cpp (201251 => 201252)</h4>
<pre class="diff"><span>
<span class="info">--- branches/safari-602.1.32-branch/Source/WebKit2/Platform/IPC/Connection.cpp 2016-05-22 16:51:44 UTC (rev 201251)
+++ branches/safari-602.1.32-branch/Source/WebKit2/Platform/IPC/Connection.cpp 2016-05-22 16:51:47 UTC (rev 201252)
</span><span class="lines">@@ -432,8 +432,12 @@
</span><span class="cx"> m_waitingForMessage = &waitingForMessage;
</span><span class="cx"> }
</span><span class="cx">
</span><ins>+ // Clamp the timeout to however much time is remaining on our clock.
+ auto now = Condition::Clock::now();
+ auto remainingClockTime = std::chrono::duration_cast<std::chrono::milliseconds>(Condition::Clock::time_point::max() - now);
+ auto absoluteTimeout = now + std::min(remainingClockTime, timeout);
+
</ins><span class="cx"> // Now wait for it to be set.
</span><del>- Condition::Clock::time_point absoluteTimeout = Condition::Clock::now() + timeout;
</del><span class="cx"> while (true) {
</span><span class="cx"> std::unique_lock<Lock> lock(m_waitForMessageMutex);
</span><span class="cx">
</span></span></pre></div>
<a id="branchessafari602132branchSourceWebKit2UIProcessAPICocoaWKWebViewmm"></a>
<div class="modfile"><h4>Modified: branches/safari-602.1.32-branch/Source/WebKit2/UIProcess/API/Cocoa/WKWebView.mm (201251 => 201252)</h4>
<pre class="diff"><span>
<span class="info">--- branches/safari-602.1.32-branch/Source/WebKit2/UIProcess/API/Cocoa/WKWebView.mm 2016-05-22 16:51:44 UTC (rev 201251)
+++ branches/safari-602.1.32-branch/Source/WebKit2/UIProcess/API/Cocoa/WKWebView.mm 2016-05-22 16:51:47 UTC (rev 201252)
</span><span class="lines">@@ -4546,11 +4546,6 @@
</span><span class="cx"> _page->send(Messages::WebPage::EndPrinting());
</span><span class="cx"> }
</span><span class="cx">
</span><del>-// FIXME: milliseconds::max() overflows when converted to nanoseconds, causing condition_variable::wait_for() to believe
-// a timeout occurred on any spurious wakeup. Use nanoseconds::max() (converted to ms) to avoid this. We should perhaps
-// change waitForAndDispatchImmediately() to take nanoseconds to avoid this issue.
-static constexpr std::chrono::milliseconds didFinishLoadingTimeout = std::chrono::duration_cast<std::chrono::milliseconds>(std::chrono::nanoseconds::max());
-
</del><span class="cx"> - (CGPDFDocumentRef)_printedDocument
</span><span class="cx"> {
</span><span class="cx"> if ([self _isDisplayingPDF]) {
</span><span class="lines">@@ -4559,7 +4554,7 @@
</span><span class="cx"> }
</span><span class="cx">
</span><span class="cx"> if (_pageIsPrintingToPDF) {
</span><del>- if (!_page->process().connection()->waitForAndDispatchImmediately<Messages::WebPageProxy::DidFinishDrawingPagesToPDF>(_page->pageID(), didFinishLoadingTimeout)) {
</del><ins>+ if (!_page->process().connection()->waitForAndDispatchImmediately<Messages::WebPageProxy::DidFinishDrawingPagesToPDF>(_page->pageID(), std::chrono::milliseconds::max())) {
</ins><span class="cx"> ASSERT_NOT_REACHED();
</span><span class="cx"> return nullptr;
</span><span class="cx"> }
</span></span></pre>
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