Prioritizing input and compositor tasks in the blink scheduler.

Source/platform/scheduler/SchedulerTest.cpp

Index: Source/platform/scheduler/SchedulerTest.cpp
diff --git a/Source/platform/scheduler/SchedulerTest.cpp b/Source/platform/scheduler/SchedulerTest.cpp
index 0b35485e9232fb0518f3c5ef9e964dca34c5de72..9697cc50fd3c4913b14a7bd645cbd905eb8e7bf6 100644
--- a/Source/platform/scheduler/SchedulerTest.cpp
+++ b/Source/platform/scheduler/SchedulerTest.cpp
@@ -10,9 +10,13 @@
 #include "public/platform/Platform.h"
 #include "public/platform/WebThread.h"
 
+#include <gmock/gmock.h>
 #include <gtest/gtest.h>
+#include <string>
+#include <vector>
 
 using blink::Scheduler;
+using namespace std;
 
 namespace {
 
@@ -116,6 +120,7 @@ private:
 class SchedulerTest : public testing::Test {
 public:
     SchedulerTest()
+        : m_reentrantCount(0)
     {
         Scheduler::initializeOnMainThread();
         m_scheduler = Scheduler::shared();
@@ -131,9 +136,47 @@ public:
         m_platformSupport.runPendingTasks();
     }
 
+    void appendToVector(string value)
+    {
+        m_order.push_back(value);
+    }
+
+    void appendToVectorReentrantTask()
+    {
+        m_reentrantOrder.push_back(m_reentrantCount++);
+
+        // Note TestRentrantTaskAfterShutdown exposes the case where a low priority task
+        // is executed after the Scheduler has shut down. It's necessary to check here
+        // that the Scheduler still exists before making the re-entrant call.
+        if (m_reentrantCount <= 4 && Scheduler::shared()) {
+            Scheduler::shared()->postTask(FROM_HERE, WTF::bind(&SchedulerTest::appendToVectorReentrantTask, this));
+        }
+    }
+
+    void appendToVectorReentrantInputTask()
+    {
+        m_reentrantOrder.push_back(m_reentrantCount++);
+
+        if (m_reentrantCount > 4)
+            return;
+        m_scheduler->postInputTask(FROM_HERE, WTF::bind(&SchedulerTest::appendToVectorReentrantInputTask, this));
+    }
+
+    void appendToVectorReentrantCompositorTask()
+    {
+        m_reentrantOrder.push_back(m_reentrantCount++);
+
+        if (m_reentrantCount > 4)
+            return;
+        m_scheduler->postCompositorTask(FROM_HERE, WTF::bind(&SchedulerTest::appendToVectorReentrantCompositorTask, this));
+    }
+
 protected:
     SchedulerTestingPlatformSupport m_platformSupport;
     Scheduler* m_scheduler;
+    std::vector<string> m_order;
+    std::vector<int> m_reentrantOrder;
+    int m_reentrantCount;
 };
 
 void orderedTestTask(int value, int* result)
@@ -154,10 +197,10 @@ void idleTestTask(int value, int* result, double allottedTime)
 TEST_F(SchedulerTest, TestPostTask)
 {
     int result = 0;
-    m_scheduler->postTask(FROM_HERE, bind(&orderedTestTask, 1, &result));
-    m_scheduler->postTask(FROM_HERE, bind(&orderedTestTask, 2, &result));
-    m_scheduler->postTask(FROM_HERE, bind(&orderedTestTask, 3, &result));
-    m_scheduler->postTask(FROM_HERE, bind(&orderedTestTask, 4, &result));
+    m_scheduler->postTask(FROM_HERE, WTF::bind(&orderedTestTask, 1, &result));
+    m_scheduler->postTask(FROM_HERE, WTF::bind(&orderedTestTask, 2, &result));
+    m_scheduler->postTask(FROM_HERE, WTF::bind(&orderedTestTask, 3, &result));
+    m_scheduler->postTask(FROM_HERE, WTF::bind(&orderedTestTask, 4, &result));
     runPendingTasks();
     EXPECT_EQ(0x1234, result);
 }
@@ -165,10 +208,22 @@ TEST_F(SchedulerTest, TestPostTask)
 TEST_F(SchedulerTest, TestPostMixedTaskTypes)
 {
     int result = 0;
-    m_scheduler->postTask(FROM_HERE, bind(&unorderedTestTask, 1, &result));
-    m_scheduler->postInputTask(FROM_HERE, bind(&unorderedTestTask, 2, &result));
-    m_scheduler->postCompositorTask(FROM_HERE, bind(&unorderedTestTask, 4, &result));
-    m_scheduler->postTask(FROM_HERE, bind(&unorderedTestTask, 8, &result));
+    m_scheduler->postTask(FROM_HERE, WTF::bind(&unorderedTestTask, 1, &result));
+    m_scheduler->postInputTask(FROM_HERE, WTF::bind(&unorderedTestTask, 2, &result));
+    m_scheduler->postCompositorTask(FROM_HERE, WTF::bind(&unorderedTestTask, 4, &result));
+    m_scheduler->postTask(FROM_HERE, WTF::bind(&unorderedTestTask, 8, &result));
+    runPendingTasks();
+    EXPECT_EQ(15, result);
+}
+
+TEST_F(SchedulerTest, TestTasksExecutedOnShutdown)
+{
+    int result = 0;
+    m_scheduler->postTask(FROM_HERE, WTF::bind(&unorderedTestTask, 1, &result));
+    m_scheduler->postInputTask(FROM_HERE, WTF::bind(&unorderedTestTask, 2, &result));
+    m_scheduler->postCompositorTask(FROM_HERE, WTF::bind(&unorderedTestTask, 4, &result));
+    m_scheduler->postTask(FROM_HERE, WTF::bind(&unorderedTestTask, 8, &result));
+    Scheduler::shutdown();
     runPendingTasks();
     EXPECT_EQ(15, result);
 }
@@ -201,12 +256,63 @@ TEST_F(SchedulerTest, TestIdleTask)
 {
     // TODO: Check task allottedTime when implemented in the scheduler.
     int result = 0;
-    m_scheduler->postIdleTask(bind<double>(&idleTestTask, 1, &result));
-    m_scheduler->postIdleTask(bind<double>(&idleTestTask, 1, &result));
-    m_scheduler->postIdleTask(bind<double>(&idleTestTask, 1, &result));
-    m_scheduler->postIdleTask(bind<double>(&idleTestTask, 1, &result));
+    m_scheduler->postIdleTask(FROM_HERE, WTF::bind<double>(&idleTestTask, 1, &result));
+    m_scheduler->postIdleTask(FROM_HERE, WTF::bind<double>(&idleTestTask, 1, &result));
+    m_scheduler->postIdleTask(FROM_HERE, WTF::bind<double>(&idleTestTask, 1, &result));
+    m_scheduler->postIdleTask(FROM_HERE, WTF::bind<double>(&idleTestTask, 1, &result));
     runPendingTasks();
     EXPECT_EQ(4, result);
 }
 
+TEST_F(SchedulerTest, TestTaskPrioritization)
+{
+    m_scheduler->postTask(FROM_HERE, WTF::bind(&SchedulerTest::appendToVector, this, string("L1")));
+    m_scheduler->postTask(FROM_HERE, WTF::bind(&SchedulerTest::appendToVector, this, string("L2")));
+    m_scheduler->postInputTask(FROM_HERE, WTF::bind(&SchedulerTest::appendToVector, this, string("I1")));
+    m_scheduler->postInputTask(FROM_HERE, WTF::bind(&SchedulerTest::appendToVector, this, string("I2")));
+    m_scheduler->postCompositorTask(FROM_HERE, WTF::bind(&SchedulerTest::appendToVector, this, string("C1")));
+    m_scheduler->postCompositorTask(FROM_HERE, WTF::bind(&SchedulerTest::appendToVector, this, string("C2")));
+
+    runPendingTasks();
+    EXPECT_THAT(m_order, testing::ElementsAre(
+        string("I1"), string("I2"), string("C1"), string("C2"), string("L1"), string("L2")));
+}
+
+TEST_F(SchedulerTest, TestRentrantTask)
+{
+    m_scheduler->postTask(FROM_HERE, WTF::bind(&SchedulerTest::appendToVectorReentrantTask, this));
+    runPendingTasks();
+
+    EXPECT_THAT(m_reentrantOrder, testing::ElementsAre(0, 1, 2, 3, 4));
+}
+
+TEST_F(SchedulerTest, TestRentrantTaskAfterShutdown)
+{
+    m_scheduler->postTask(
+        FROM_HERE, WTF::bind(&SchedulerTest::appendToVectorReentrantTask, this));
+    Scheduler::shutdown();
+    EXPECT_TRUE(m_reentrantOrder.empty());
+
+    // Regular tasks are delegated to the main run loop, and since the scheduler has shutdown it's
+    // no longer possible to post any more tasks through it. Hence only 1 task gets executed.
+    runPendingTasks();
+    EXPECT_THAT(m_reentrantOrder, testing::ElementsAre(0));
+}
+
+TEST_F(SchedulerTest, TestRentrantInputTaskDuringShutdown)
+{
+    m_scheduler->postInputTask(FROM_HERE, WTF::bind(&SchedulerTest::appendToVectorReentrantInputTask, this));
+    Scheduler::shutdown();
+
+    EXPECT_THAT(m_reentrantOrder, testing::ElementsAre(0, 1, 2, 3, 4));
+}
+
+TEST_F(SchedulerTest, TestRentrantCompositorTaskDuringShutdown)
+{
+    m_scheduler->postCompositorTask(FROM_HERE, WTF::bind(&SchedulerTest::appendToVectorReentrantCompositorTask, this));
+    Scheduler::shutdown();
+
+    EXPECT_THAT(m_reentrantOrder, testing::ElementsAre(0, 1, 2, 3, 4));
+}
+
 } // namespace