1 files changed, 126 insertions, 0 deletions
diff --git a/Source/WebKit2/UIProcess/ProcessThrottler.cpp b/Source/WebKit2/UIProcess/ProcessThrottler.cpp
new file mode 100644
index 000000000..77b0b8c71
--- /dev/null
+++ b/Source/WebKit2/UIProcess/ProcessThrottler.cpp
@@ -0,0 +1,126 @@
+/*
+ * Copyright (C) 2014 Apple Inc. All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY APPLE INC. AND ITS CONTRIBUTORS ``AS IS''
+ * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
+ * THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
+ * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL APPLE INC. OR ITS CONTRIBUTORS
+ * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
+ * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO , PROCUREMENT OF
+ * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
+ * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
+ * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
+ * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF
+ * THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#include "config.h"
+#include "ProcessThrottler.h"
+
+#include "Logging.h"
+#include "ProcessThrottlerClient.h"
+
+namespace WebKit {
+    
+static const unsigned processSuspensionTimeout = 30;
+    
+ProcessThrottler::ProcessThrottler(ProcessThrottlerClient& process)
+    : m_process(process)
+    , m_suspendTimer(RunLoop::main(), this, &ProcessThrottler::suspendTimerFired)
+    , m_foregroundCounter([this](RefCounterEvent) { updateAssertion(); })
+    , m_backgroundCounter([this](RefCounterEvent) { updateAssertion(); })
+    , m_suspendMessageCount(0)
+{
+}
+    
+AssertionState ProcessThrottler::assertionState()
+{
+    ASSERT(!m_suspendTimer.isActive());
+    
+    if (m_foregroundCounter.value())
+        return AssertionState::Foreground;
+    if (m_backgroundCounter.value())
+        return AssertionState::Background;
+    return AssertionState::Suspended;
+}
+    
+void ProcessThrottler::updateAssertionNow()
+{
+    m_suspendTimer.stop();
+    if (m_assertion) {
+        if (m_assertion->state() != assertionState())
+            RELEASE_LOG(ProcessSuspension, "%p - ProcessThrottler::updateAssertionNow() updating process assertion state to %u (foregroundActivities: %lu, backgroundActivities: %lu)", this, assertionState(), m_foregroundCounter.value(), m_backgroundCounter.value());
+        m_assertion->setState(assertionState());
+        m_process.didSetAssertionState(assertionState());
+    }
+}
+    
+void ProcessThrottler::updateAssertion()
+{
+    // If the process is currently runnable but will be suspended then first give it a chance to complete what it was doing
+    // and clean up - move it to the background and send it a message to notify. Schedule a timeout so it can't stay running
+    // in the background for too long.
+    if (m_assertion && m_assertion->state() != AssertionState::Suspended && !m_foregroundCounter.value() && !m_backgroundCounter.value()) {
+        ++m_suspendMessageCount;
+        RELEASE_LOG(ProcessSuspension, "%p - ProcessThrottler::updateAssertion() sending PrepareToSuspend IPC", this);
+        m_process.sendPrepareToSuspend();
+        m_suspendTimer.startOneShot(processSuspensionTimeout);
+        m_assertion->setState(AssertionState::Background);
+        m_process.didSetAssertionState(AssertionState::Background);
+        return;
+    }
+
+    bool shouldBeRunnable = m_foregroundCounter.value() || m_backgroundCounter.value();
+
+    // If we're currently waiting for the Web process to do suspension cleanup, but no longer need to be suspended, tell the Web process to cancel the cleanup.
+    if (m_suspendTimer.isActive() && shouldBeRunnable)
+        m_process.sendCancelPrepareToSuspend();
+    
+    if (m_assertion && m_assertion->state() == AssertionState::Suspended && shouldBeRunnable)
+        m_process.sendProcessDidResume();
+
+    updateAssertionNow();
+}
+
+void ProcessThrottler::didConnectToProcess(pid_t pid)
+{
+    m_suspendTimer.stop();
+    m_assertion = std::make_unique<ProcessAndUIAssertion>(pid, assertionState());
+    m_process.didSetAssertionState(assertionState());
+    m_assertion->setClient(*this);
+}
+    
+void ProcessThrottler::suspendTimerFired()
+{
+    updateAssertionNow();
+}
+    
+void ProcessThrottler::processReadyToSuspend()
+{
+    if (!--m_suspendMessageCount)
+        updateAssertionNow();
+    ASSERT(m_suspendMessageCount >= 0);
+}
+
+void ProcessThrottler::didCancelProcessSuspension()
+{
+    if (!--m_suspendMessageCount)
+        updateAssertionNow();
+    ASSERT(m_suspendMessageCount >= 0);
+}
+
+void ProcessThrottler::assertionWillExpireImminently()
+{
+    m_process.sendProcessWillSuspendImminently();
+}
+
+}