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<dt>Revision</dt> <dd><a href="http://trac.webkit.org/projects/webkit/changeset/169362">169362</a></dd>
<dt>Author</dt> <dd>barraclough@apple.com</dd>
<dt>Date</dt> <dd>2014-05-26 17:02:34 -0700 (Mon, 26 May 2014)</dd>
</dl>

<h3>Log Message</h3>
<pre>Add UI process watchdog on iOS to ensure WebProcess connections close
https://bugs.webkit.org/show_bug.cgi?id=133200
&lt;rdar://problem/16997983&gt;

Reviewed by Darin Adler.

When the WebProcessProxy wants to disconnect from a WebContent process it just drops the connection,
and hopes the connection closes. There is a watchdog thread in the ChildProcess to try to ensure this
happens.

On iOS the process may not be runnable at the time, preventing termination. Instead add a watchdog in
the UI process to make the process runnable, and to terminate if it doesn't quit in a timely fashion.

* Platform/IPC/Connection.h:
    - added terminateSoon.
* Platform/IPC/mac/ConnectionMac.mm:
(IPC::ConnectionTerminationWatchdog::ConnectionTerminationWatchdog):
    - take an assertion to make the process runnable, and start a watchdog timer.
(IPC::ConnectionTerminationWatchdog::watchdogTimerFired):
    - if the process hasn't quit by the timer the watchdog fires, kill it.
(IPC::Connection::terminateSoon):
    - create a ConnectionTerminationWatchdog.
* UIProcess/WebProcessProxy.cpp:
(WebKit::WebProcessProxy::removeWebPage):
    - when disconnecting from a process, first tell it to terminateSoon.</pre>

<h3>Modified Paths</h3>
<ul>
<li><a href="#trunkSourceWebKit2ChangeLog">trunk/Source/WebKit2/ChangeLog</a></li>
<li><a href="#trunkSourceWebKit2PlatformIPCConnectionh">trunk/Source/WebKit2/Platform/IPC/Connection.h</a></li>
<li><a href="#trunkSourceWebKit2PlatformIPCmacConnectionMacmm">trunk/Source/WebKit2/Platform/IPC/mac/ConnectionMac.mm</a></li>
<li><a href="#trunkSourceWebKit2UIProcessWebProcessProxycpp">trunk/Source/WebKit2/UIProcess/WebProcessProxy.cpp</a></li>
</ul>

</div>
<div id="patch">
<h3>Diff</h3>
<a id="trunkSourceWebKit2ChangeLog"></a>
<div class="modfile"><h4>Modified: trunk/Source/WebKit2/ChangeLog (169361 => 169362)</h4>
<pre class="diff"><span>
<span class="info">--- trunk/Source/WebKit2/ChangeLog        2014-05-26 23:42:49 UTC (rev 169361)
+++ trunk/Source/WebKit2/ChangeLog        2014-05-27 00:02:34 UTC (rev 169362)
</span><span class="lines">@@ -1,3 +1,31 @@
</span><ins>+2014-05-22  Gavin Barraclough  &lt;baraclough@apple.com&gt;
+
+        Add UI process watchdog on iOS to ensure WebProcess connections close
+        https://bugs.webkit.org/show_bug.cgi?id=133200
+        &lt;rdar://problem/16997983&gt;
+
+        Reviewed by Darin Adler.
+
+        When the WebProcessProxy wants to disconnect from a WebContent process it just drops the connection,
+        and hopes the connection closes. There is a watchdog thread in the ChildProcess to try to ensure this
+        happens.
+
+        On iOS the process may not be runnable at the time, preventing termination. Instead add a watchdog in
+        the UI process to make the process runnable, and to terminate if it doesn't quit in a timely fashion.
+
+        * Platform/IPC/Connection.h:
+            - added terminateSoon.
+        * Platform/IPC/mac/ConnectionMac.mm:
+        (IPC::ConnectionTerminationWatchdog::ConnectionTerminationWatchdog):
+            - take an assertion to make the process runnable, and start a watchdog timer.
+        (IPC::ConnectionTerminationWatchdog::watchdogTimerFired):
+            - if the process hasn't quit by the timer the watchdog fires, kill it.
+        (IPC::Connection::terminateSoon):
+            - create a ConnectionTerminationWatchdog.
+        * UIProcess/WebProcessProxy.cpp:
+        (WebKit::WebProcessProxy::removeWebPage):
+            - when disconnecting from a process, first tell it to terminateSoon.
+
</ins><span class="cx"> 2014-05-26  Sam Weinig  &lt;sam@webkit.org&gt;
</span><span class="cx"> 
</span><span class="cx">         [WebKit2] Add better default preferences while keeping backward compatibility for the C-SPI
</span></span></pre></div>
<a id="trunkSourceWebKit2PlatformIPCConnectionh"></a>
<div class="modfile"><h4>Modified: trunk/Source/WebKit2/Platform/IPC/Connection.h (169361 => 169362)</h4>
<pre class="diff"><span>
<span class="info">--- trunk/Source/WebKit2/Platform/IPC/Connection.h        2014-05-26 23:42:49 UTC (rev 169361)
+++ trunk/Source/WebKit2/Platform/IPC/Connection.h        2014-05-27 00:02:34 UTC (rev 169362)
</span><span class="lines">@@ -183,6 +183,7 @@
</span><span class="cx"> 
</span><span class="cx"> #if PLATFORM(COCOA)
</span><span class="cx">     bool kill();
</span><ins>+    void terminateSoon(double intervalInSeconds);
</ins><span class="cx"> #endif
</span><span class="cx"> 
</span><span class="cx"> private:
</span></span></pre></div>
<a id="trunkSourceWebKit2PlatformIPCmacConnectionMacmm"></a>
<div class="modfile"><h4>Modified: trunk/Source/WebKit2/Platform/IPC/mac/ConnectionMac.mm (169361 => 169362)</h4>
<pre class="diff"><span>
<span class="info">--- trunk/Source/WebKit2/Platform/IPC/mac/ConnectionMac.mm        2014-05-26 23:42:49 UTC (rev 169361)
+++ trunk/Source/WebKit2/Platform/IPC/mac/ConnectionMac.mm        2014-05-27 00:02:34 UTC (rev 169362)
</span><span class="lines">@@ -36,6 +36,10 @@
</span><span class="cx"> #include &lt;wtf/RunLoop.h&gt;
</span><span class="cx"> #include &lt;xpc/xpc.h&gt;
</span><span class="cx"> 
</span><ins>+#if PLATFORM(IOS)
+#include &quot;ProcessAssertion.h&quot;
+#endif
+
</ins><span class="cx"> #if __has_include(&lt;xpc/private.h&gt;)
</span><span class="cx"> #include &lt;xpc/private.h&gt;
</span><span class="cx"> #else
</span><span class="lines">@@ -65,6 +69,41 @@
</span><span class="cx">     MessageBodyIsOutOfLine = 1 &lt;&lt; 0
</span><span class="cx"> };
</span><span class="cx">     
</span><ins>+// ConnectionTerminationWatchdog does two things:
+// 1) It sets a watchdog timer to kill the peered process.
+// 2) On iOS, make the process runnable for the duration of the watchdog
+//    to ensure it has a chance to terminate cleanly.
+class ConnectionTerminationWatchdog {
+public:
+    static void createConnectionTerminationWatchdog(XPCPtr&lt;xpc_connection_t&gt;&amp; xpcConnection, double intervalInSeconds)
+    {
+        new ConnectionTerminationWatchdog(xpcConnection, intervalInSeconds);
+    }
+    
+private:
+    ConnectionTerminationWatchdog(XPCPtr&lt;xpc_connection_t&gt;&amp; xpcConnection, double intervalInSeconds)
+        : m_xpcConnection(xpcConnection)
+        , m_watchdogTimer(RunLoop::main(), this, &amp;ConnectionTerminationWatchdog::watchdogTimerFired)
+#if PLATFORM(IOS)
+        , m_assertion(std::make_unique&lt;WebKit::ProcessAssertion&gt;(xpc_connection_get_pid(m_xpcConnection.get()), WebKit::AssertionState::Background))
+#endif
+    {
+        m_watchdogTimer.startOneShot(intervalInSeconds);
+    }
+    
+    void watchdogTimerFired()
+    {
+        xpc_connection_kill(m_xpcConnection.get(), SIGKILL);
+        delete this;
+    }
+
+    XPCPtr&lt;xpc_connection_t&gt; m_xpcConnection;
+    RunLoop::Timer&lt;ConnectionTerminationWatchdog&gt; m_watchdogTimer;
+#if PLATFORM(IOS)
+    std::unique_ptr&lt;WebKit::ProcessAssertion&gt; m_assertion;
+#endif
+};
+    
</ins><span class="cx"> void Connection::platformInvalidate()
</span><span class="cx"> {
</span><span class="cx">     if (!m_isConnected)
</span><span class="lines">@@ -97,7 +136,13 @@
</span><span class="cx"> 
</span><span class="cx">     m_xpcConnection = nullptr;
</span><span class="cx"> }
</span><del>-
</del><ins>+    
+void Connection::terminateSoon(double intervalInSeconds)
+{
+    if (m_xpcConnection)
+        ConnectionTerminationWatchdog::createConnectionTerminationWatchdog(m_xpcConnection, intervalInSeconds);
+}
+    
</ins><span class="cx"> void Connection::platformInitialize(Identifier identifier)
</span><span class="cx"> {
</span><span class="cx"> #if !PLATFORM(IOS)
</span></span></pre></div>
<a id="trunkSourceWebKit2UIProcessWebProcessProxycpp"></a>
<div class="modfile"><h4>Modified: trunk/Source/WebKit2/UIProcess/WebProcessProxy.cpp (169361 => 169362)</h4>
<pre class="diff"><span>
<span class="info">--- trunk/Source/WebKit2/UIProcess/WebProcessProxy.cpp        2014-05-26 23:42:49 UTC (rev 169361)
+++ trunk/Source/WebKit2/UIProcess/WebProcessProxy.cpp        2014-05-27 00:02:34 UTC (rev 169362)
</span><span class="lines">@@ -210,6 +210,11 @@
</span><span class="cx">     // We only allow this when using a network process, as otherwise the WebProcess needs to preserve its session state.
</span><span class="cx">     if (m_context-&gt;usesNetworkProcess() &amp;&amp; canTerminateChildProcess()) {
</span><span class="cx">         abortProcessLaunchIfNeeded();
</span><ins>+#if PLATFORM(IOS)
+        // On iOS deploy a watchdog in the UI process, since the content may be suspended.
+        // 30s should be sufficient for any outstanding activity to complete cleanly.
+        connection()-&gt;terminateSoon(30);
+#endif
</ins><span class="cx">         disconnect();
</span><span class="cx">     }
</span><span class="cx"> }
</span></span></pre>
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