/*
 * Copyright 2015 The Netty Project
 *
 * The Netty Project licenses this file to you 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.
 */

package io.netty.buffer;

import io.netty.util.concurrent.FastThreadLocal;
import io.netty.util.concurrent.FastThreadLocalThread;
import io.netty.util.internal.PlatformDependent;
import io.netty.util.internal.SystemPropertyUtil;
import org.junit.Assume;
import org.junit.Test;

import java.util.ArrayList;
import java.util.List;
import java.util.Queue;
import java.util.concurrent.ConcurrentLinkedQueue;
import java.util.concurrent.CountDownLatch;
import java.util.concurrent.atomic.AtomicBoolean;
import java.util.concurrent.atomic.AtomicReference;
import java.util.concurrent.locks.LockSupport;

import static java.util.concurrent.TimeUnit.MILLISECONDS;
import static org.junit.Assert.assertEquals;
import static org.junit.Assert.assertFalse;
import static org.junit.Assert.assertNotNull;
import static org.junit.Assert.assertTrue;

public class PooledByteBufAllocatorTest extends AbstractByteBufAllocatorTest<PooledByteBufAllocator> {

    @Override
    protected PooledByteBufAllocator newAllocator(boolean preferDirect) {
        return new PooledByteBufAllocator(preferDirect);
    }

    @Override
    protected PooledByteBufAllocator newUnpooledAllocator() {
        return new PooledByteBufAllocator(0, 0, 8192, 1);
    }

    @Override
    protected long expectedUsedMemory(PooledByteBufAllocator allocator, int capacity) {
        return allocator.metric().chunkSize();
    }

    @Override
    protected long expectedUsedMemoryAfterRelease(PooledByteBufAllocator allocator, int capacity) {
        // This is the case as allocations will start in qInit and chunks in qInit will never be released until
        // these are moved to q000.
        // See https://www.bsdcan.org/2006/papers/jemalloc.pdf
        return allocator.metric().chunkSize();
    }

    @Test
    public void testTrim() {
        PooledByteBufAllocator allocator = newAllocator(true);

        // Should return false as we never allocated from this thread yet.
        assertFalse(allocator.trimCurrentThreadCache());

        ByteBuf directBuffer = allocator.directBuffer();

        assertTrue(directBuffer.release());

        // Should return true now a cache exists for the calling thread.
        assertTrue(allocator.trimCurrentThreadCache());
    }

    @Test
    public void testPooledUnsafeHeapBufferAndUnsafeDirectBuffer() {
        PooledByteBufAllocator allocator = newAllocator(true);
        ByteBuf directBuffer = allocator.directBuffer();
        assertInstanceOf(directBuffer,
                PlatformDependent.hasUnsafe() ? PooledUnsafeDirectByteBuf.class : PooledDirectByteBuf.class);
        directBuffer.release();

        ByteBuf heapBuffer = allocator.heapBuffer();
        assertInstanceOf(heapBuffer,
                PlatformDependent.hasUnsafe() ? PooledUnsafeHeapByteBuf.class : PooledHeapByteBuf.class);
        heapBuffer.release();
    }

    @Test
    public void testIOBuffersAreDirectWhenUnsafeAvailableOrDirectBuffersPooled() {
        PooledByteBufAllocator allocator = newAllocator(true);
        ByteBuf ioBuffer = allocator.ioBuffer();

        assertTrue(ioBuffer.isDirect());
        ioBuffer.release();

        PooledByteBufAllocator unpooledAllocator = newUnpooledAllocator();
        ioBuffer = unpooledAllocator.ioBuffer();

        if (PlatformDependent.hasUnsafe()) {
            assertTrue(ioBuffer.isDirect());
        } else {
            assertFalse(ioBuffer.isDirect());
        }
        ioBuffer.release();
    }

    @Test
    public void testWithoutUseCacheForAllThreads() {
        assertFalse(Thread.currentThread() instanceof FastThreadLocalThread);

        PooledByteBufAllocator pool = new PooledByteBufAllocator(
                /*preferDirect=*/ false,
                /*nHeapArena=*/ 1,
                /*nDirectArena=*/ 1,
                /*pageSize=*/8192,
                /*maxOrder=*/ 11,
                /*tinyCacheSize=*/ 0,
                /*smallCacheSize=*/ 0,
                /*normalCacheSize=*/ 0,
                /*useCacheForAllThreads=*/ false);
        ByteBuf buf = pool.buffer(1);
        buf.release();
    }

    @Test
    public void testArenaMetricsNoCache() {
        testArenaMetrics0(new PooledByteBufAllocator(true, 2, 2, 8192, 11, 0, 0, 0), 100, 0, 100, 100);
    }

    @Test
    public void testArenaMetricsCache() {
        testArenaMetrics0(new PooledByteBufAllocator(true, 2, 2, 8192, 11, 1000, 1000, 1000, true, 0), 100, 1, 1, 0);
    }

    @Test
    public void testArenaMetricsNoCacheAlign() {
        Assume.assumeTrue(PooledByteBufAllocator.isDirectMemoryCacheAlignmentSupported());
        testArenaMetrics0(new PooledByteBufAllocator(true, 2, 2, 8192, 11, 0, 0, 0, true, 64), 100, 0, 100, 100);
    }

    @Test
    public void testArenaMetricsCacheAlign() {
        Assume.assumeTrue(PooledByteBufAllocator.isDirectMemoryCacheAlignmentSupported());
        testArenaMetrics0(new PooledByteBufAllocator(true, 2, 2, 8192, 11, 1000, 1000, 1000, true, 64), 100, 1, 1, 0);
    }

    private static void testArenaMetrics0(
            PooledByteBufAllocator allocator, int num, int expectedActive, int expectedAlloc, int expectedDealloc) {
        for (int i = 0; i < num; i++) {
            assertTrue(allocator.directBuffer().release());
            assertTrue(allocator.heapBuffer().release());
        }

        assertArenaMetrics(allocator.metric().directArenas(), expectedActive, expectedAlloc, expectedDealloc);
        assertArenaMetrics(allocator.metric().heapArenas(), expectedActive, expectedAlloc, expectedDealloc);
    }

    private static void assertArenaMetrics(
            List<PoolArenaMetric> arenaMetrics, int expectedActive, int expectedAlloc, int expectedDealloc) {
        int active = 0;
        int alloc = 0;
        int dealloc = 0;
        for (PoolArenaMetric arena : arenaMetrics) {
            active += arena.numActiveAllocations();
            alloc += arena.numAllocations();
            dealloc += arena.numDeallocations();
        }
        assertEquals(expectedActive, active);
        assertEquals(expectedAlloc, alloc);
        assertEquals(expectedDealloc, dealloc);
    }

    @Test
    public void testPoolChunkListMetric() {
        for (PoolArenaMetric arenaMetric: PooledByteBufAllocator.DEFAULT.metric().heapArenas()) {
            assertPoolChunkListMetric(arenaMetric);
        }
    }

    private static void assertPoolChunkListMetric(PoolArenaMetric arenaMetric) {
        List<PoolChunkListMetric> lists = arenaMetric.chunkLists();
        assertEquals(6, lists.size());
        assertPoolChunkListMetric(lists.get(0), 1, 25);
        assertPoolChunkListMetric(lists.get(1), 1, 50);
        assertPoolChunkListMetric(lists.get(2), 25, 75);
        assertPoolChunkListMetric(lists.get(4), 75, 100);
        assertPoolChunkListMetric(lists.get(5), 100, 100);
    }

    private static void assertPoolChunkListMetric(PoolChunkListMetric m, int min, int max) {
        assertEquals(min, m.minUsage());
        assertEquals(max, m.maxUsage());
    }

    @Test
    public void testSmallSubpageMetric() {
        PooledByteBufAllocator allocator = new PooledByteBufAllocator(true, 1, 1, 8192, 11, 0, 0, 0);
        ByteBuf buffer = allocator.heapBuffer(500);
        try {
            PoolArenaMetric metric = allocator.metric().heapArenas().get(0);
            PoolSubpageMetric subpageMetric = metric.smallSubpages().get(0);
            assertEquals(1, subpageMetric.maxNumElements() - subpageMetric.numAvailable());
        } finally {
            buffer.release();
        }
    }

    @Test
    public void testTinySubpageMetric() {
        PooledByteBufAllocator allocator = new PooledByteBufAllocator(true, 1, 1, 8192, 11, 0, 0, 0);
        ByteBuf buffer = allocator.heapBuffer(1);
        try {
            PoolArenaMetric metric = allocator.metric().heapArenas().get(0);
            PoolSubpageMetric subpageMetric = metric.tinySubpages().get(0);
            assertEquals(1, subpageMetric.maxNumElements() - subpageMetric.numAvailable());
        } finally {
            buffer.release();
        }
    }

    @Test
    public void testAllocNotNull() {
        PooledByteBufAllocator allocator = new PooledByteBufAllocator(true, 1, 1, 8192, 11, 0, 0, 0);
        // Huge allocation
        testAllocNotNull(allocator, allocator.metric().chunkSize() + 1);
        // Normal allocation
        testAllocNotNull(allocator, 1024);
        // Small allocation
        testAllocNotNull(allocator, 512);
        // Tiny allocation
        testAllocNotNull(allocator, 1);
    }

    private static void testAllocNotNull(PooledByteBufAllocator allocator, int capacity) {
        ByteBuf buffer = allocator.heapBuffer(capacity);
        assertNotNull(buffer.alloc());
        assertTrue(buffer.release());
        assertNotNull(buffer.alloc());
    }

    @Test
    public void testFreePoolChunk() {
        int chunkSize = 16 * 1024 * 1024;
        PooledByteBufAllocator allocator = new PooledByteBufAllocator(true, 1, 0, 8192, 11, 0, 0, 0);
        ByteBuf buffer = allocator.heapBuffer(chunkSize);
        List<PoolArenaMetric> arenas = allocator.metric().heapArenas();
        assertEquals(1, arenas.size());
        List<PoolChunkListMetric> lists = arenas.get(0).chunkLists();
        assertEquals(6, lists.size());

        assertFalse(lists.get(0).iterator().hasNext());
        assertFalse(lists.get(1).iterator().hasNext());
        assertFalse(lists.get(2).iterator().hasNext());
        assertFalse(lists.get(3).iterator().hasNext());
        assertFalse(lists.get(4).iterator().hasNext());

        // Must end up in the 6th PoolChunkList
        assertTrue(lists.get(5).iterator().hasNext());
        assertTrue(buffer.release());

        // Should be completely removed and so all PoolChunkLists must be empty
        assertFalse(lists.get(0).iterator().hasNext());
        assertFalse(lists.get(1).iterator().hasNext());
        assertFalse(lists.get(2).iterator().hasNext());
        assertFalse(lists.get(3).iterator().hasNext());
        assertFalse(lists.get(4).iterator().hasNext());
        assertFalse(lists.get(5).iterator().hasNext());
    }

    @Test (timeout = 4000)
    public void testThreadCacheDestroyedByThreadCleaner() throws InterruptedException {
        testThreadCacheDestroyed(false);
    }

    @Test (timeout = 4000)
    public void testThreadCacheDestroyedAfterExitRun() throws InterruptedException {
        testThreadCacheDestroyed(true);
    }

    private static void testThreadCacheDestroyed(boolean useRunnable) throws InterruptedException {
        int numArenas = 11;
        final PooledByteBufAllocator allocator =
            new PooledByteBufAllocator(numArenas, numArenas, 8192, 1);

        final AtomicBoolean threadCachesCreated = new AtomicBoolean(true);

        final Runnable task = () -> {
            ByteBuf buf = allocator.newHeapBuffer(1024, 1024);
            for (int i = 0; i < buf.capacity(); i++) {
                buf.writeByte(0);
            }

            // Make sure that thread caches are actually created,
            // so that down below we are not testing for zero
            // thread caches without any of them ever having been initialized.
            if (allocator.metric().numThreadLocalCaches() == 0) {
                threadCachesCreated.set(false);
            }

            buf.release();
        };

        for (int i = 0; i < numArenas; i++) {
            final FastThreadLocalThread thread;
            if (useRunnable) {
                thread = new FastThreadLocalThread(task);
                assertTrue(thread.willCleanupFastThreadLocals());
            } else {
                thread = new FastThreadLocalThread() {
                    @Override
                    public void run() {
                        task.run();
                    }
                };
                assertFalse(thread.willCleanupFastThreadLocals());
            }
            thread.start();
            thread.join();
        }

        // Wait for the ThreadDeathWatcher to have destroyed all thread caches
        while (allocator.metric().numThreadLocalCaches() > 0) {
            // Signal we want to have a GC run to ensure we can process our ThreadCleanerReference
            System.gc();
            System.runFinalization();
            LockSupport.parkNanos(MILLISECONDS.toNanos(100));
        }

        assertTrue(threadCachesCreated.get());
    }

    @Test(timeout = 3000)
    public void testNumThreadCachesWithNoDirectArenas() throws InterruptedException {
        int numHeapArenas = 1;
        final PooledByteBufAllocator allocator =
            new PooledByteBufAllocator(numHeapArenas, 0, 8192, 1);

        ThreadCache tcache0 = createNewThreadCache(allocator);
        assertEquals(1, allocator.metric().numThreadLocalCaches());

        ThreadCache tcache1 = createNewThreadCache(allocator);
        assertEquals(2, allocator.metric().numThreadLocalCaches());

        tcache0.destroy();
        assertEquals(1, allocator.metric().numThreadLocalCaches());

        tcache1.destroy();
        assertEquals(0, allocator.metric().numThreadLocalCaches());
    }

    @Test(timeout = 3000)
    public void testThreadCacheToArenaMappings() throws InterruptedException {
        int numArenas = 2;
        final PooledByteBufAllocator allocator =
            new PooledByteBufAllocator(numArenas, numArenas, 8192, 1);

        ThreadCache tcache0 = createNewThreadCache(allocator);
        ThreadCache tcache1 = createNewThreadCache(allocator);
        assertEquals(2, allocator.metric().numThreadLocalCaches());
        assertEquals(1, allocator.metric().heapArenas().get(0).numThreadCaches());
        assertEquals(1, allocator.metric().heapArenas().get(1).numThreadCaches());
        assertEquals(1, allocator.metric().directArenas().get(0).numThreadCaches());
        assertEquals(1, allocator.metric().directArenas().get(0).numThreadCaches());

        tcache1.destroy();

        assertEquals(1, allocator.metric().numThreadLocalCaches());
        assertEquals(1, allocator.metric().heapArenas().get(0).numThreadCaches());
        assertEquals(0, allocator.metric().heapArenas().get(1).numThreadCaches());
        assertEquals(1, allocator.metric().directArenas().get(0).numThreadCaches());
        assertEquals(0, allocator.metric().directArenas().get(1).numThreadCaches());

        ThreadCache tcache2 = createNewThreadCache(allocator);
        assertEquals(2, allocator.metric().numThreadLocalCaches());
        assertEquals(1, allocator.metric().heapArenas().get(0).numThreadCaches());
        assertEquals(1, allocator.metric().heapArenas().get(1).numThreadCaches());
        assertEquals(1, allocator.metric().directArenas().get(0).numThreadCaches());
        assertEquals(1, allocator.metric().directArenas().get(1).numThreadCaches());

        tcache0.destroy();
        assertEquals(1, allocator.metric().numThreadLocalCaches());

        tcache2.destroy();
        assertEquals(0, allocator.metric().numThreadLocalCaches());
        assertEquals(0, allocator.metric().heapArenas().get(0).numThreadCaches());
        assertEquals(0, allocator.metric().heapArenas().get(1).numThreadCaches());
        assertEquals(0, allocator.metric().directArenas().get(0).numThreadCaches());
        assertEquals(0, allocator.metric().directArenas().get(1).numThreadCaches());
    }

    private static ThreadCache createNewThreadCache(final PooledByteBufAllocator allocator)
            throws InterruptedException {
        final CountDownLatch latch = new CountDownLatch(1);
        final CountDownLatch cacheLatch = new CountDownLatch(1);
        final Thread t = new FastThreadLocalThread(() -> {
            ByteBuf buf = allocator.newHeapBuffer(1024, 1024);

            // Countdown the latch after we allocated a buffer. At this point the cache must exists.
            cacheLatch.countDown();

            buf.writeZero(buf.capacity());

            try {
                latch.await();
            } catch (InterruptedException e) {
                throw new IllegalStateException(e);
            }

            buf.release();

            FastThreadLocal.removeAll();
        });
        t.start();

        // Wait until we allocated a buffer and so be sure the thread was started and the cache exists.
        cacheLatch.await();

        return () -> {
            latch.countDown();
            t.join();
        };
    }

    private interface ThreadCache {
        void destroy() throws InterruptedException;
    }

    @Test
    public void testConcurrentUsage() throws Throwable {
        long runningTime = MILLISECONDS.toNanos(SystemPropertyUtil.getLong(
                "io.netty.buffer.PooledByteBufAllocatorTest.testConcurrentUsageTime", 15000));

        // We use no caches and only one arena to maximize the chance of hitting the race-condition we
        // had before.
        ByteBufAllocator allocator = new PooledByteBufAllocator(true, 1, 1, 8192, 11, 0, 0, 0);
        List<AllocationThread> threads = new ArrayList<>();
        try {
            for (int i = 0; i < 512; i++) {
                AllocationThread thread = new AllocationThread(allocator);
                thread.start();
                threads.add(thread);
            }

            long start = System.nanoTime();
            while (!isExpired(start, runningTime)) {
                checkForErrors(threads);
                Thread.sleep(100);
            }
        } finally {
            // First mark all AllocationThreads to complete their work and then wait until these are complete
            // and rethrow if there was any error.
            for (AllocationThread t : threads) {
                t.markAsFinished();
            }

            for (AllocationThread t: threads) {
                t.joinAndCheckForError();
            }
        }
    }

    private static boolean isExpired(long start, long expireTime) {
        return System.nanoTime() - start > expireTime;
    }

    private static void checkForErrors(List<AllocationThread> threads) throws Throwable {
        for (AllocationThread t : threads) {
            if (t.isFinished()) {
                t.checkForError();
            }
        }
    }

    private static final class AllocationThread extends Thread {

        private static final int[] ALLOCATION_SIZES = new int[16 * 1024];
        static {
            for (int i = 0; i < ALLOCATION_SIZES.length; i++) {
                ALLOCATION_SIZES[i] = i;
            }
        }

        private final Queue<ByteBuf> buffers = new ConcurrentLinkedQueue<>();
        private final ByteBufAllocator allocator;
        private final AtomicReference<Object> finish = new AtomicReference<>();

        AllocationThread(ByteBufAllocator allocator) {
            this.allocator = allocator;
        }

        @Override
        public void run() {
            try {
                int idx = 0;
                while (finish.get() == null) {
                    for (int i = 0; i < 10; i++) {
                        buffers.add(allocator.directBuffer(
                                ALLOCATION_SIZES[Math.abs(idx++ % ALLOCATION_SIZES.length)],
                                Integer.MAX_VALUE));
                    }
                    releaseBuffers();
                }
            } catch (Throwable cause) {
                finish.set(cause);
            } finally {
                releaseBuffers();
            }
        }

        private void releaseBuffers() {
            for (;;) {
                ByteBuf buf = buffers.poll();
                if (buf == null) {
                    break;
                }
                buf.release();
            }
        }

        boolean isFinished() {
            return finish.get() != null;
        }

        void markAsFinished() {
            finish.compareAndSet(null, Boolean.TRUE);
        }

        void joinAndCheckForError() throws Throwable {
            try {
                // Mark as finish if not already done but ensure we not override the previous set error.
                join();
            } finally {
                releaseBuffers();
            }
            checkForError();
        }

        void checkForError() throws Throwable {
            Object obj = finish.get();
            if (obj instanceof Throwable) {
                throw (Throwable) obj;
            }
        }
    }
}
