PL286/system/core/libutils/tests/RefBase_test.cpp

/*
 * Copyright (C) 2016 The Android Open Source Project
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

#include <gtest/gtest.h>

#include <utils/StrongPointer.h>
#include <utils/RefBase.h>

#include <thread>
#include <atomic>
#include <sched.h>
#include <errno.h>

// Enhanced version of StrongPointer_test, but using RefBase underneath.

using namespace android;

static constexpr int NITERS = 1000000;

static constexpr int INITIAL_STRONG_VALUE = 1 << 28;  // Mirroring RefBase definition.

class Foo : public RefBase {
public:
    Foo(bool* deleted_check) : mDeleted(deleted_check) {
        *mDeleted = false;
    }

    ~Foo() {
        *mDeleted = true;
    }
private:
    bool* mDeleted;
};

TEST(RefBase, StrongMoves) {
    bool isDeleted;
    Foo* foo = new Foo(&isDeleted);
    ASSERT_EQ(INITIAL_STRONG_VALUE, foo->getStrongCount());
    ASSERT_FALSE(isDeleted) << "Already deleted...?";
    sp<Foo> sp1(foo);
    wp<Foo> wp1(sp1);
    ASSERT_EQ(1, foo->getStrongCount());
    // Weak count includes both strong and weak references.
    ASSERT_EQ(2, foo->getWeakRefs()->getWeakCount());
    {
        sp<Foo> sp2 = std::move(sp1);
        ASSERT_EQ(1, foo->getStrongCount())
                << "std::move failed, incremented refcnt";
        ASSERT_EQ(nullptr, sp1.get()) << "std::move failed, sp1 is still valid";
        // The strong count isn't increasing, let's double check the old object
        // is properly reset and doesn't early delete
        sp1 = std::move(sp2);
    }
    ASSERT_FALSE(isDeleted) << "deleted too early! still has a reference!";
    {
        // Now let's double check it deletes on time
        sp<Foo> sp2 = std::move(sp1);
    }
    ASSERT_TRUE(isDeleted) << "foo was leaked!";
    ASSERT_TRUE(wp1.promote().get() == nullptr);
}

TEST(RefBase, WeakCopies) {
    bool isDeleted;
    Foo* foo = new Foo(&isDeleted);
    EXPECT_EQ(0, foo->getWeakRefs()->getWeakCount());
    ASSERT_FALSE(isDeleted) << "Foo (weak) already deleted...?";
    wp<Foo> wp1(foo);
    EXPECT_EQ(1, foo->getWeakRefs()->getWeakCount());
    {
        wp<Foo> wp2 = wp1;
        ASSERT_EQ(2, foo->getWeakRefs()->getWeakCount());
    }
    EXPECT_EQ(1, foo->getWeakRefs()->getWeakCount());
    ASSERT_FALSE(isDeleted) << "deleted too early! still has a reference!";
    wp1 = nullptr;
    ASSERT_FALSE(isDeleted) << "Deletion on wp destruction should no longer occur";
}


// Set up a situation in which we race with visit2AndRremove() to delete
// 2 strong references.  Bar destructor checks that there are no early
// deletions and prior updates are visible to destructor.
class Bar : public RefBase {
public:
    Bar(std::atomic<int>* delete_count) : mVisited1(false), mVisited2(false),
            mDeleteCount(delete_count) {
    }

    ~Bar() {
        EXPECT_TRUE(mVisited1);
        EXPECT_TRUE(mVisited2);
        (*mDeleteCount)++;
    }
    bool mVisited1;
    bool mVisited2;
private:
    std::atomic<int>* mDeleteCount;
};

static sp<Bar> buffer;
static std::atomic<bool> bufferFull(false);

// Wait until bufferFull has value val.
static inline void waitFor(bool val) {
    while (bufferFull != val) {}
}

cpu_set_t otherCpus;

// Divide the cpus we're allowed to run on into myCpus and otherCpus.
// Set origCpus to the processors we were originally allowed to run on.
// Return false if origCpus doesn't include at least processors 0 and 1.
static bool setExclusiveCpus(cpu_set_t* origCpus /* out */,
        cpu_set_t* myCpus /* out */, cpu_set_t* otherCpus) {
    if (sched_getaffinity(0, sizeof(cpu_set_t), origCpus) != 0) {
        return false;
    }
    if (!CPU_ISSET(0,  origCpus) || !CPU_ISSET(1, origCpus)) {
        return false;
    }
    CPU_ZERO(myCpus);
    CPU_ZERO(otherCpus);
    CPU_OR(myCpus, myCpus, origCpus);
    CPU_OR(otherCpus, otherCpus, origCpus);
    for (unsigned i = 0; i < CPU_SETSIZE; ++i) {
        // I get the even cores, the other thread gets the odd ones.
        if (i & 1) {
            CPU_CLR(i, myCpus);
        } else {
            CPU_CLR(i, otherCpus);
        }
    }
    return true;
}

static void visit2AndRemove() {
    if (sched_setaffinity(0, sizeof(cpu_set_t), &otherCpus) != 0) {
        FAIL() << "setaffinity returned:" << errno;
    }
    for (int i = 0; i < NITERS; ++i) {
        waitFor(true);
        buffer->mVisited2 = true;
        buffer = nullptr;
        bufferFull = false;
    }
}

TEST(RefBase, RacingDestructors) {
    cpu_set_t origCpus;
    cpu_set_t myCpus;
    // Restrict us and the helper thread to disjoint cpu sets.
    // This prevents us from getting scheduled against each other,
    // which would be atrociously slow.
    if (setExclusiveCpus(&origCpus, &myCpus, &otherCpus)) {
        std::thread t(visit2AndRemove);
        std::atomic<int> deleteCount(0);
        if (sched_setaffinity(0, sizeof(cpu_set_t), &myCpus) != 0) {
            FAIL() << "setaffinity returned:" << errno;
        }
        for (int i = 0; i < NITERS; ++i) {
            waitFor(false);
            Bar* bar = new Bar(&deleteCount);
            sp<Bar> sp3(bar);
            buffer = sp3;
            bufferFull = true;
            ASSERT_TRUE(bar->getStrongCount() >= 1);
            // Weak count includes strong count.
            ASSERT_TRUE(bar->getWeakRefs()->getWeakCount() >= 1);
            sp3->mVisited1 = true;
            sp3 = nullptr;
        }
        t.join();
        if (sched_setaffinity(0, sizeof(cpu_set_t), &origCpus) != 0) {
            FAIL();
        }
        ASSERT_EQ(NITERS, deleteCount) << "Deletions missed!";
    }  // Otherwise this is slow and probably pointless on a uniprocessor.
}

static wp<Bar> wpBuffer;
static std::atomic<bool> wpBufferFull(false);

// Wait until wpBufferFull has value val.
static inline void wpWaitFor(bool val) {
    while (wpBufferFull != val) {}
}

static void visit3AndRemove() {
    if (sched_setaffinity(0, sizeof(cpu_set_t), &otherCpus) != 0) {
        FAIL() << "setaffinity returned:" << errno;
    }
    for (int i = 0; i < NITERS; ++i) {
        wpWaitFor(true);
        {
            sp<Bar> sp1 = wpBuffer.promote();
            // We implicitly check that sp1 != NULL
            sp1->mVisited2 = true;
        }
        wpBuffer = nullptr;
        wpBufferFull = false;
    }
}

TEST(RefBase, RacingPromotions) {
    cpu_set_t origCpus;
    cpu_set_t myCpus;
    // Restrict us and the helper thread to disjoint cpu sets.
    // This prevents us from getting scheduled against each other,
    // which would be atrociously slow.
    if (setExclusiveCpus(&origCpus, &myCpus, &otherCpus)) {
        std::thread t(visit3AndRemove);
        std::atomic<int> deleteCount(0);
        if (sched_setaffinity(0, sizeof(cpu_set_t), &myCpus) != 0) {
            FAIL() << "setaffinity returned:" << errno;
        }
        for (int i = 0; i < NITERS; ++i) {
            Bar* bar = new Bar(&deleteCount);
            wp<Bar> wp1(bar);
            bar->mVisited1 = true;
            if (i % (NITERS / 10) == 0) {
                // Do this rarely, since it generates a log message.
                wp1 = nullptr;  // No longer destroys the object.
                wp1 = bar;
            }
            wpBuffer = wp1;
            ASSERT_EQ(bar->getWeakRefs()->getWeakCount(), 2);
            wpBufferFull = true;
            // Promotion races with that in visit3AndRemove.
            // This may or may not succeed, but it shouldn't interfere with
            // the concurrent one.
            sp<Bar> sp1 = wp1.promote();
            wpWaitFor(false);  // Waits for other thread to drop strong pointer.
            sp1 = nullptr;
            // No strong pointers here.
            sp1 = wp1.promote();
            ASSERT_EQ(sp1.get(), nullptr) << "Dead wp promotion succeeded!";
        }
        t.join();
        if (sched_setaffinity(0, sizeof(cpu_set_t), &origCpus) != 0) {
            FAIL();
        }
        ASSERT_EQ(NITERS, deleteCount) << "Deletions missed!";
    }  // Otherwise this is slow and probably pointless on a uniprocessor.
}