libs/utils/tests/PollLoop_test.cpp - LeafOS-Project/android_frameworks_base - Gitiles

 //
 // Copyright 2010 The Android Open Source Project
 //

 #include <utils/PollLoop.h>
 #include <utils/Timers.h>
 #include <utils/StopWatch.h>
 #include <gtest/gtest.h>
 #include <unistd.h>
 #include <time.h>

 #include "TestHelpers.h"

 // # of milliseconds to fudge stopwatch measurements
 #define TIMING_TOLERANCE_MS 25

 namespace android {

 class DelayedWake : public DelayedTask {
     sp<PollLoop> mPollLoop;

 public:
     DelayedWake(int delayMillis, const sp<PollLoop> pollLoop) :
         DelayedTask(delayMillis), mPollLoop(pollLoop) {
     }

 protected:
     virtual void doTask() {
         mPollLoop->wake();
     }
 };

 class DelayedWriteSignal : public DelayedTask {
     Pipe* mPipe;

 public:
     DelayedWriteSignal(int delayMillis, Pipe* pipe) :
         DelayedTask(delayMillis), mPipe(pipe) {
     }

 protected:
     virtual void doTask() {
         mPipe->writeSignal();
     }
 };

 class CallbackHandler {
 public:
     void setCallback(const sp<PollLoop>& pollLoop, int fd, int events) {
         pollLoop->setCallback(fd, events, staticHandler, this);
     }

 protected:
     virtual ~CallbackHandler() { }

     virtual bool handler(int fd, int events) = 0;

 private:
     static bool staticHandler(int fd, int events, void* data) {
         return static_cast<CallbackHandler*>(data)->handler(fd, events);
     }
 };

 class StubCallbackHandler : public CallbackHandler {
 public:
     bool nextResult;
     int callbackCount;

     int fd;
     int events;

     StubCallbackHandler(bool nextResult) : nextResult(nextResult),
             callbackCount(0), fd(-1), events(-1) {
     }

 protected:
     virtual bool handler(int fd, int events) {
         callbackCount += 1;
         this->fd = fd;
         this->events = events;
         return nextResult;
     }
 };

 class PollLoopTest : public testing::Test {
 protected:
     sp<PollLoop> mPollLoop;

     virtual void SetUp() {
         mPollLoop = new PollLoop(false);
     }

     virtual void TearDown() {
         mPollLoop.clear();
     }
 };


 TEST_F(PollLoopTest, PollOnce_WhenNonZeroTimeoutAndNotAwoken_WaitsForTimeoutAndReturnsFalse) {
     StopWatch stopWatch("pollOnce");
     int32_t result = mPollLoop->pollOnce(100);
     int32_t elapsedMillis = ns2ms(stopWatch.elapsedTime());

     EXPECT_NEAR(100, elapsedMillis, TIMING_TOLERANCE_MS)
             << "elapsed time should approx. equal timeout";
     EXPECT_EQ(result, PollLoop::POLL_TIMEOUT)
             << "pollOnce result should be POLL_TIMEOUT";
 }

 TEST_F(PollLoopTest, PollOnce_WhenNonZeroTimeoutAndAwokenBeforeWaiting_ImmediatelyReturnsTrue) {
     mPollLoop->wake();

     StopWatch stopWatch("pollOnce");
     int32_t result = mPollLoop->pollOnce(1000);
     int32_t elapsedMillis = ns2ms(stopWatch.elapsedTime());

     EXPECT_NEAR(0, elapsedMillis, TIMING_TOLERANCE_MS)
             << "elapsed time should approx. zero because wake() was called before waiting";
     EXPECT_EQ(result, PollLoop::POLL_CALLBACK)
             << "pollOnce result should be POLL_CALLBACK because loop was awoken";
 }

 TEST_F(PollLoopTest, PollOnce_WhenNonZeroTimeoutAndAwokenWhileWaiting_PromptlyReturnsTrue) {
     sp<DelayedWake> delayedWake = new DelayedWake(100, mPollLoop);
     delayedWake->run();

     StopWatch stopWatch("pollOnce");
     int32_t result = mPollLoop->pollOnce(1000);
     int32_t elapsedMillis = ns2ms(stopWatch.elapsedTime());

     EXPECT_NEAR(100, elapsedMillis, TIMING_TOLERANCE_MS)
             << "elapsed time should approx. equal wake delay";
     EXPECT_EQ(result, PollLoop::POLL_CALLBACK)
             << "pollOnce result should be POLL_CALLBACK because loop was awoken";
 }

 TEST_F(PollLoopTest, PollOnce_WhenZeroTimeoutAndNoRegisteredFDs_ImmediatelyReturnsFalse) {
     StopWatch stopWatch("pollOnce");
     int32_t result = mPollLoop->pollOnce(0);
     int32_t elapsedMillis = ns2ms(stopWatch.elapsedTime());

     EXPECT_NEAR(0, elapsedMillis, TIMING_TOLERANCE_MS)
             << "elapsed time should be approx. zero";
     EXPECT_EQ(result, PollLoop::POLL_TIMEOUT)
             << "pollOnce result should be POLL_TIMEOUT";
 }

 TEST_F(PollLoopTest, PollOnce_WhenZeroTimeoutAndNoSignalledFDs_ImmediatelyReturnsFalse) {
     Pipe pipe;
     StubCallbackHandler handler(true);

     handler.setCallback(mPollLoop, pipe.receiveFd, POLL_IN);

     StopWatch stopWatch("pollOnce");
     int32_t result = mPollLoop->pollOnce(0);
     int32_t elapsedMillis = ns2ms(stopWatch.elapsedTime());

     EXPECT_NEAR(0, elapsedMillis, TIMING_TOLERANCE_MS)
             << "elapsed time should be approx. zero";
     EXPECT_EQ(result, PollLoop::POLL_TIMEOUT)
             << "pollOnce result should be POLL_TIMEOUT";
     EXPECT_EQ(0, handler.callbackCount)
             << "callback should not have been invoked because FD was not signalled";
 }

 TEST_F(PollLoopTest, PollOnce_WhenZeroTimeoutAndSignalledFD_ImmediatelyInvokesCallbackAndReturnsTrue) {
     Pipe pipe;
     StubCallbackHandler handler(true);

     ASSERT_EQ(OK, pipe.writeSignal());
     handler.setCallback(mPollLoop, pipe.receiveFd, POLL_IN);

     StopWatch stopWatch("pollOnce");
     int32_t result = mPollLoop->pollOnce(0);
     int32_t elapsedMillis = ns2ms(stopWatch.elapsedTime());

     EXPECT_NEAR(0, elapsedMillis, TIMING_TOLERANCE_MS)
             << "elapsed time should be approx. zero";
     EXPECT_EQ(result, PollLoop::POLL_CALLBACK)
             << "pollOnce result should be POLL_CALLBACK because FD was signalled";
     EXPECT_EQ(1, handler.callbackCount)
             << "callback should be invoked exactly once";
     EXPECT_EQ(pipe.receiveFd, handler.fd)
             << "callback should have received pipe fd as parameter";
     EXPECT_EQ(POLL_IN, handler.events)
             << "callback should have received POLL_IN as events";
 }

 TEST_F(PollLoopTest, PollOnce_WhenNonZeroTimeoutAndNoSignalledFDs_WaitsForTimeoutAndReturnsFalse) {
     Pipe pipe;
     StubCallbackHandler handler(true);

     handler.setCallback(mPollLoop, pipe.receiveFd, POLL_IN);

     StopWatch stopWatch("pollOnce");
     int32_t result = mPollLoop->pollOnce(100);
     int32_t elapsedMillis = ns2ms(stopWatch.elapsedTime());

     EXPECT_NEAR(100, elapsedMillis, TIMING_TOLERANCE_MS)
             << "elapsed time should approx. equal timeout";
     EXPECT_EQ(result, PollLoop::POLL_TIMEOUT)
             << "pollOnce result should be POLL_TIMEOUT";
     EXPECT_EQ(0, handler.callbackCount)
             << "callback should not have been invoked because FD was not signalled";
 }

 TEST_F(PollLoopTest, PollOnce_WhenNonZeroTimeoutAndSignalledFDBeforeWaiting_ImmediatelyInvokesCallbackAndReturnsTrue) {
     Pipe pipe;
     StubCallbackHandler handler(true);

     pipe.writeSignal();
     handler.setCallback(mPollLoop, pipe.receiveFd, POLL_IN);

     StopWatch stopWatch("pollOnce");
     int32_t result = mPollLoop->pollOnce(100);
     int32_t elapsedMillis = ns2ms(stopWatch.elapsedTime());

     ASSERT_EQ(OK, pipe.readSignal())
             << "signal should actually have been written";
     EXPECT_NEAR(0, elapsedMillis, TIMING_TOLERANCE_MS)
             << "elapsed time should be approx. zero";
     EXPECT_EQ(result, PollLoop::POLL_CALLBACK)
             << "pollOnce result should be POLL_CALLBACK because FD was signalled";
     EXPECT_EQ(1, handler.callbackCount)
             << "callback should be invoked exactly once";
     EXPECT_EQ(pipe.receiveFd, handler.fd)
             << "callback should have received pipe fd as parameter";
     EXPECT_EQ(POLL_IN, handler.events)
             << "callback should have received POLL_IN as events";
 }

 TEST_F(PollLoopTest, PollOnce_WhenNonZeroTimeoutAndSignalledFDWhileWaiting_PromptlyInvokesCallbackAndReturnsTrue) {
     Pipe pipe;
     StubCallbackHandler handler(true);
     sp<DelayedWriteSignal> delayedWriteSignal = new DelayedWriteSignal(100, & pipe);

     handler.setCallback(mPollLoop, pipe.receiveFd, POLL_IN);
     delayedWriteSignal->run();

     StopWatch stopWatch("pollOnce");
     int32_t result = mPollLoop->pollOnce(1000);
     int32_t elapsedMillis = ns2ms(stopWatch.elapsedTime());

     ASSERT_EQ(OK, pipe.readSignal())
             << "signal should actually have been written";
     EXPECT_NEAR(100, elapsedMillis, TIMING_TOLERANCE_MS)
             << "elapsed time should approx. equal signal delay";
     EXPECT_EQ(result, PollLoop::POLL_CALLBACK)
             << "pollOnce result should be POLL_CALLBACK because FD was signalled";
     EXPECT_EQ(1, handler.callbackCount)
             << "callback should be invoked exactly once";
     EXPECT_EQ(pipe.receiveFd, handler.fd)
             << "callback should have received pipe fd as parameter";
     EXPECT_EQ(POLL_IN, handler.events)
             << "callback should have received POLL_IN as events";
 }

 TEST_F(PollLoopTest, PollOnce_WhenCallbackAddedThenRemoved_CallbackShouldNotBeInvoked) {
     Pipe pipe;
     StubCallbackHandler handler(true);

     handler.setCallback(mPollLoop, pipe.receiveFd, POLL_IN);
     pipe.writeSignal(); // would cause FD to be considered signalled
     mPollLoop->removeCallback(pipe.receiveFd);

     StopWatch stopWatch("pollOnce");
     int32_t result = mPollLoop->pollOnce(100);
     int32_t elapsedMillis = ns2ms(stopWatch.elapsedTime());

     ASSERT_EQ(OK, pipe.readSignal())
             << "signal should actually have been written";
     EXPECT_NEAR(100, elapsedMillis, TIMING_TOLERANCE_MS)
             << "elapsed time should approx. equal timeout because FD was no longer registered";
     EXPECT_EQ(result, PollLoop::POLL_TIMEOUT)
             << "pollOnce result should be POLL_TIMEOUT";
     EXPECT_EQ(0, handler.callbackCount)
             << "callback should not be invoked";
 }

 TEST_F(PollLoopTest, PollOnce_WhenCallbackReturnsFalse_CallbackShouldNotBeInvokedAgainLater) {
     Pipe pipe;
     StubCallbackHandler handler(false);

     handler.setCallback(mPollLoop, pipe.receiveFd, POLL_IN);

     // First loop: Callback is registered and FD is signalled.
     pipe.writeSignal();

     StopWatch stopWatch("pollOnce");
     int32_t result = mPollLoop->pollOnce(0);
     int32_t elapsedMillis = ns2ms(stopWatch.elapsedTime());

     ASSERT_EQ(OK, pipe.readSignal())
             << "signal should actually have been written";
     EXPECT_NEAR(0, elapsedMillis, TIMING_TOLERANCE_MS)
             << "elapsed time should approx. equal zero because FD was already signalled";
     EXPECT_EQ(result, PollLoop::POLL_CALLBACK)
             << "pollOnce result should be POLL_CALLBACK because FD was signalled";
     EXPECT_EQ(1, handler.callbackCount)
             << "callback should be invoked";

     // Second loop: Callback is no longer registered and FD is signalled.
     pipe.writeSignal();

     stopWatch.reset();
     result = mPollLoop->pollOnce(0);
     elapsedMillis = ns2ms(stopWatch.elapsedTime());

     ASSERT_EQ(OK, pipe.readSignal())
             << "signal should actually have been written";
     EXPECT_NEAR(0, elapsedMillis, TIMING_TOLERANCE_MS)
             << "elapsed time should approx. equal zero because timeout was zero";
     EXPECT_EQ(result, PollLoop::POLL_TIMEOUT)
             << "pollOnce result should be POLL_TIMEOUT";
     EXPECT_EQ(1, handler.callbackCount)
             << "callback should not be invoked this time";
 }

 TEST_F(PollLoopTest, RemoveCallback_WhenCallbackNotAdded_ReturnsFalse) {
     bool result = mPollLoop->removeCallback(1);

     EXPECT_FALSE(result)
             << "removeCallback should return false because FD not registered";
 }

 TEST_F(PollLoopTest, RemoveCallback_WhenCallbackAddedThenRemovedTwice_ReturnsTrueFirstTimeAndReturnsFalseSecondTime) {
     Pipe pipe;
     StubCallbackHandler handler(false);
     handler.setCallback(mPollLoop, pipe.receiveFd, POLL_IN);

     // First time.
     bool result = mPollLoop->removeCallback(pipe.receiveFd);

     EXPECT_TRUE(result)
             << "removeCallback should return true first time because FD was registered";

     // Second time.
     result = mPollLoop->removeCallback(pipe.receiveFd);

     EXPECT_FALSE(result)
             << "removeCallback should return false second time because FD was no longer registered";
 }

 TEST_F(PollLoopTest, PollOnce_WhenCallbackAddedTwice_OnlySecondCallbackShouldBeInvoked) {
     Pipe pipe;
     StubCallbackHandler handler1(true);
     StubCallbackHandler handler2(true);

     handler1.setCallback(mPollLoop, pipe.receiveFd, POLL_IN);
     handler2.setCallback(mPollLoop, pipe.receiveFd, POLL_IN); // replace it
     pipe.writeSignal(); // would cause FD to be considered signalled

     StopWatch stopWatch("pollOnce");
     int32_t result = mPollLoop->pollOnce(100);
     int32_t elapsedMillis = ns2ms(stopWatch.elapsedTime());

     ASSERT_EQ(OK, pipe.readSignal())
             << "signal should actually have been written";
     EXPECT_NEAR(0, elapsedMillis, TIMING_TOLERANCE_MS)
             << "elapsed time should approx. zero because FD was already signalled";
     EXPECT_EQ(result, PollLoop::POLL_CALLBACK)
             << "pollOnce result should be POLL_CALLBACK because FD was signalled";
     EXPECT_EQ(0, handler1.callbackCount)
             << "original handler callback should not be invoked because it was replaced";
     EXPECT_EQ(1, handler2.callbackCount)
             << "replacement handler callback should be invoked";
 }


 } // namespace android
	//
	// Copyright 2010 The Android Open Source Project
	//

	#include <utils/PollLoop.h>
	#include <utils/Timers.h>
	#include <utils/StopWatch.h>
	#include <gtest/gtest.h>
	#include <unistd.h>
	#include <time.h>

	#include "TestHelpers.h"

	// # of milliseconds to fudge stopwatch measurements
	#define TIMING_TOLERANCE_MS 25

	namespace android {

	class DelayedWake : public DelayedTask {
	sp<PollLoop> mPollLoop;

	public:
	DelayedWake(int delayMillis, const sp<PollLoop> pollLoop) :
	DelayedTask(delayMillis), mPollLoop(pollLoop) {
	}

	protected:
	virtual void doTask() {
	mPollLoop->wake();
	}
	};

	class DelayedWriteSignal : public DelayedTask {
	Pipe* mPipe;

	public:
	DelayedWriteSignal(int delayMillis, Pipe* pipe) :
	DelayedTask(delayMillis), mPipe(pipe) {
	}

	protected:
	virtual void doTask() {
	mPipe->writeSignal();
	}
	};

	class CallbackHandler {
	public:
	void setCallback(const sp<PollLoop>& pollLoop, int fd, int events) {
	pollLoop->setCallback(fd, events, staticHandler, this);
	}

	protected:
	virtual ~CallbackHandler() { }

	virtual bool handler(int fd, int events) = 0;

	private:
	static bool staticHandler(int fd, int events, void* data) {
	return static_cast<CallbackHandler*>(data)->handler(fd, events);
	}
	};

	class StubCallbackHandler : public CallbackHandler {
	public:
	bool nextResult;
	int callbackCount;

	int fd;
	int events;

	StubCallbackHandler(bool nextResult) : nextResult(nextResult),
	callbackCount(0), fd(-1), events(-1) {
	}

	protected:
	virtual bool handler(int fd, int events) {
	callbackCount += 1;
	this->fd = fd;
	this->events = events;
	return nextResult;
	}
	};

	class PollLoopTest : public testing::Test {
	protected:
	sp<PollLoop> mPollLoop;

	virtual void SetUp() {
	mPollLoop = new PollLoop(false);
	}

	virtual void TearDown() {
	mPollLoop.clear();
	}
	};


	TEST_F(PollLoopTest, PollOnce_WhenNonZeroTimeoutAndNotAwoken_WaitsForTimeoutAndReturnsFalse) {
	StopWatch stopWatch("pollOnce");
	int32_t result = mPollLoop->pollOnce(100);
	int32_t elapsedMillis = ns2ms(stopWatch.elapsedTime());

	EXPECT_NEAR(100, elapsedMillis, TIMING_TOLERANCE_MS)
	<< "elapsed time should approx. equal timeout";
	EXPECT_EQ(result, PollLoop::POLL_TIMEOUT)
	<< "pollOnce result should be POLL_TIMEOUT";
	}

	TEST_F(PollLoopTest, PollOnce_WhenNonZeroTimeoutAndAwokenBeforeWaiting_ImmediatelyReturnsTrue) {
	mPollLoop->wake();

	StopWatch stopWatch("pollOnce");
	int32_t result = mPollLoop->pollOnce(1000);
	int32_t elapsedMillis = ns2ms(stopWatch.elapsedTime());

	EXPECT_NEAR(0, elapsedMillis, TIMING_TOLERANCE_MS)
	<< "elapsed time should approx. zero because wake() was called before waiting";
	EXPECT_EQ(result, PollLoop::POLL_CALLBACK)
	<< "pollOnce result should be POLL_CALLBACK because loop was awoken";
	}

	TEST_F(PollLoopTest, PollOnce_WhenNonZeroTimeoutAndAwokenWhileWaiting_PromptlyReturnsTrue) {
	sp<DelayedWake> delayedWake = new DelayedWake(100, mPollLoop);
	delayedWake->run();

	StopWatch stopWatch("pollOnce");
	int32_t result = mPollLoop->pollOnce(1000);
	int32_t elapsedMillis = ns2ms(stopWatch.elapsedTime());

	EXPECT_NEAR(100, elapsedMillis, TIMING_TOLERANCE_MS)
	<< "elapsed time should approx. equal wake delay";
	EXPECT_EQ(result, PollLoop::POLL_CALLBACK)
	<< "pollOnce result should be POLL_CALLBACK because loop was awoken";
	}

	TEST_F(PollLoopTest, PollOnce_WhenZeroTimeoutAndNoRegisteredFDs_ImmediatelyReturnsFalse) {
	StopWatch stopWatch("pollOnce");
	int32_t result = mPollLoop->pollOnce(0);
	int32_t elapsedMillis = ns2ms(stopWatch.elapsedTime());

	EXPECT_NEAR(0, elapsedMillis, TIMING_TOLERANCE_MS)
	<< "elapsed time should be approx. zero";
	EXPECT_EQ(result, PollLoop::POLL_TIMEOUT)
	<< "pollOnce result should be POLL_TIMEOUT";
	}

	TEST_F(PollLoopTest, PollOnce_WhenZeroTimeoutAndNoSignalledFDs_ImmediatelyReturnsFalse) {
	Pipe pipe;
	StubCallbackHandler handler(true);

	handler.setCallback(mPollLoop, pipe.receiveFd, POLL_IN);

	StopWatch stopWatch("pollOnce");
	int32_t result = mPollLoop->pollOnce(0);
	int32_t elapsedMillis = ns2ms(stopWatch.elapsedTime());

	EXPECT_NEAR(0, elapsedMillis, TIMING_TOLERANCE_MS)
	<< "elapsed time should be approx. zero";
	EXPECT_EQ(result, PollLoop::POLL_TIMEOUT)
	<< "pollOnce result should be POLL_TIMEOUT";
	EXPECT_EQ(0, handler.callbackCount)
	<< "callback should not have been invoked because FD was not signalled";
	}

	TEST_F(PollLoopTest, PollOnce_WhenZeroTimeoutAndSignalledFD_ImmediatelyInvokesCallbackAndReturnsTrue) {
	Pipe pipe;
	StubCallbackHandler handler(true);

	ASSERT_EQ(OK, pipe.writeSignal());
	handler.setCallback(mPollLoop, pipe.receiveFd, POLL_IN);

	StopWatch stopWatch("pollOnce");
	int32_t result = mPollLoop->pollOnce(0);
	int32_t elapsedMillis = ns2ms(stopWatch.elapsedTime());

	EXPECT_NEAR(0, elapsedMillis, TIMING_TOLERANCE_MS)
	<< "elapsed time should be approx. zero";
	EXPECT_EQ(result, PollLoop::POLL_CALLBACK)
	<< "pollOnce result should be POLL_CALLBACK because FD was signalled";
	EXPECT_EQ(1, handler.callbackCount)
	<< "callback should be invoked exactly once";
	EXPECT_EQ(pipe.receiveFd, handler.fd)
	<< "callback should have received pipe fd as parameter";
	EXPECT_EQ(POLL_IN, handler.events)
	<< "callback should have received POLL_IN as events";
	}

	TEST_F(PollLoopTest, PollOnce_WhenNonZeroTimeoutAndNoSignalledFDs_WaitsForTimeoutAndReturnsFalse) {
	Pipe pipe;
	StubCallbackHandler handler(true);

	handler.setCallback(mPollLoop, pipe.receiveFd, POLL_IN);

	StopWatch stopWatch("pollOnce");
	int32_t result = mPollLoop->pollOnce(100);
	int32_t elapsedMillis = ns2ms(stopWatch.elapsedTime());

	EXPECT_NEAR(100, elapsedMillis, TIMING_TOLERANCE_MS)
	<< "elapsed time should approx. equal timeout";
	EXPECT_EQ(result, PollLoop::POLL_TIMEOUT)
	<< "pollOnce result should be POLL_TIMEOUT";
	EXPECT_EQ(0, handler.callbackCount)
	<< "callback should not have been invoked because FD was not signalled";
	}

	TEST_F(PollLoopTest, PollOnce_WhenNonZeroTimeoutAndSignalledFDBeforeWaiting_ImmediatelyInvokesCallbackAndReturnsTrue) {
	Pipe pipe;
	StubCallbackHandler handler(true);

	pipe.writeSignal();
	handler.setCallback(mPollLoop, pipe.receiveFd, POLL_IN);

	StopWatch stopWatch("pollOnce");
	int32_t result = mPollLoop->pollOnce(100);
	int32_t elapsedMillis = ns2ms(stopWatch.elapsedTime());

	ASSERT_EQ(OK, pipe.readSignal())
	<< "signal should actually have been written";
	EXPECT_NEAR(0, elapsedMillis, TIMING_TOLERANCE_MS)
	<< "elapsed time should be approx. zero";
	EXPECT_EQ(result, PollLoop::POLL_CALLBACK)
	<< "pollOnce result should be POLL_CALLBACK because FD was signalled";
	EXPECT_EQ(1, handler.callbackCount)
	<< "callback should be invoked exactly once";
	EXPECT_EQ(pipe.receiveFd, handler.fd)
	<< "callback should have received pipe fd as parameter";
	EXPECT_EQ(POLL_IN, handler.events)
	<< "callback should have received POLL_IN as events";
	}

	TEST_F(PollLoopTest, PollOnce_WhenNonZeroTimeoutAndSignalledFDWhileWaiting_PromptlyInvokesCallbackAndReturnsTrue) {
	Pipe pipe;
	StubCallbackHandler handler(true);
	sp<DelayedWriteSignal> delayedWriteSignal = new DelayedWriteSignal(100, & pipe);

	handler.setCallback(mPollLoop, pipe.receiveFd, POLL_IN);
	delayedWriteSignal->run();

	StopWatch stopWatch("pollOnce");
	int32_t result = mPollLoop->pollOnce(1000);
	int32_t elapsedMillis = ns2ms(stopWatch.elapsedTime());

	ASSERT_EQ(OK, pipe.readSignal())
	<< "signal should actually have been written";
	EXPECT_NEAR(100, elapsedMillis, TIMING_TOLERANCE_MS)
	<< "elapsed time should approx. equal signal delay";
	EXPECT_EQ(result, PollLoop::POLL_CALLBACK)
	<< "pollOnce result should be POLL_CALLBACK because FD was signalled";
	EXPECT_EQ(1, handler.callbackCount)
	<< "callback should be invoked exactly once";
	EXPECT_EQ(pipe.receiveFd, handler.fd)
	<< "callback should have received pipe fd as parameter";
	EXPECT_EQ(POLL_IN, handler.events)
	<< "callback should have received POLL_IN as events";
	}

	TEST_F(PollLoopTest, PollOnce_WhenCallbackAddedThenRemoved_CallbackShouldNotBeInvoked) {
	Pipe pipe;
	StubCallbackHandler handler(true);

	handler.setCallback(mPollLoop, pipe.receiveFd, POLL_IN);
	pipe.writeSignal(); // would cause FD to be considered signalled
	mPollLoop->removeCallback(pipe.receiveFd);

	StopWatch stopWatch("pollOnce");
	int32_t result = mPollLoop->pollOnce(100);
	int32_t elapsedMillis = ns2ms(stopWatch.elapsedTime());

	ASSERT_EQ(OK, pipe.readSignal())
	<< "signal should actually have been written";
	EXPECT_NEAR(100, elapsedMillis, TIMING_TOLERANCE_MS)
	<< "elapsed time should approx. equal timeout because FD was no longer registered";
	EXPECT_EQ(result, PollLoop::POLL_TIMEOUT)
	<< "pollOnce result should be POLL_TIMEOUT";
	EXPECT_EQ(0, handler.callbackCount)
	<< "callback should not be invoked";
	}

	TEST_F(PollLoopTest, PollOnce_WhenCallbackReturnsFalse_CallbackShouldNotBeInvokedAgainLater) {
	Pipe pipe;
	StubCallbackHandler handler(false);

	handler.setCallback(mPollLoop, pipe.receiveFd, POLL_IN);

	// First loop: Callback is registered and FD is signalled.
	pipe.writeSignal();

	StopWatch stopWatch("pollOnce");
	int32_t result = mPollLoop->pollOnce(0);
	int32_t elapsedMillis = ns2ms(stopWatch.elapsedTime());

	ASSERT_EQ(OK, pipe.readSignal())
	<< "signal should actually have been written";
	EXPECT_NEAR(0, elapsedMillis, TIMING_TOLERANCE_MS)
	<< "elapsed time should approx. equal zero because FD was already signalled";
	EXPECT_EQ(result, PollLoop::POLL_CALLBACK)
	<< "pollOnce result should be POLL_CALLBACK because FD was signalled";
	EXPECT_EQ(1, handler.callbackCount)
	<< "callback should be invoked";

	// Second loop: Callback is no longer registered and FD is signalled.
	pipe.writeSignal();

	stopWatch.reset();
	result = mPollLoop->pollOnce(0);
	elapsedMillis = ns2ms(stopWatch.elapsedTime());

	ASSERT_EQ(OK, pipe.readSignal())
	<< "signal should actually have been written";
	EXPECT_NEAR(0, elapsedMillis, TIMING_TOLERANCE_MS)
	<< "elapsed time should approx. equal zero because timeout was zero";
	EXPECT_EQ(result, PollLoop::POLL_TIMEOUT)
	<< "pollOnce result should be POLL_TIMEOUT";
	EXPECT_EQ(1, handler.callbackCount)
	<< "callback should not be invoked this time";
	}

	TEST_F(PollLoopTest, RemoveCallback_WhenCallbackNotAdded_ReturnsFalse) {
	bool result = mPollLoop->removeCallback(1);

	EXPECT_FALSE(result)
	<< "removeCallback should return false because FD not registered";
	}

	TEST_F(PollLoopTest, RemoveCallback_WhenCallbackAddedThenRemovedTwice_ReturnsTrueFirstTimeAndReturnsFalseSecondTime) {
	Pipe pipe;
	StubCallbackHandler handler(false);
	handler.setCallback(mPollLoop, pipe.receiveFd, POLL_IN);

	// First time.
	bool result = mPollLoop->removeCallback(pipe.receiveFd);

	EXPECT_TRUE(result)
	<< "removeCallback should return true first time because FD was registered";

	// Second time.
	result = mPollLoop->removeCallback(pipe.receiveFd);

	EXPECT_FALSE(result)
	<< "removeCallback should return false second time because FD was no longer registered";
	}

	TEST_F(PollLoopTest, PollOnce_WhenCallbackAddedTwice_OnlySecondCallbackShouldBeInvoked) {
	Pipe pipe;
	StubCallbackHandler handler1(true);
	StubCallbackHandler handler2(true);

	handler1.setCallback(mPollLoop, pipe.receiveFd, POLL_IN);
	handler2.setCallback(mPollLoop, pipe.receiveFd, POLL_IN); // replace it
	pipe.writeSignal(); // would cause FD to be considered signalled

	StopWatch stopWatch("pollOnce");
	int32_t result = mPollLoop->pollOnce(100);
	int32_t elapsedMillis = ns2ms(stopWatch.elapsedTime());

	ASSERT_EQ(OK, pipe.readSignal())
	<< "signal should actually have been written";
	EXPECT_NEAR(0, elapsedMillis, TIMING_TOLERANCE_MS)
	<< "elapsed time should approx. zero because FD was already signalled";
	EXPECT_EQ(result, PollLoop::POLL_CALLBACK)
	<< "pollOnce result should be POLL_CALLBACK because FD was signalled";
	EXPECT_EQ(0, handler1.callbackCount)
	<< "original handler callback should not be invoked because it was replaced";
	EXPECT_EQ(1, handler2.callbackCount)
	<< "replacement handler callback should be invoked";
	}


	} // namespace android