Examples with CachePolicy io.pravega.segmentstore.server.CachePolicy used on opensource projects

Example 1 with CachePolicy

use of io.pravega.segmentstore.server.CachePolicy in project pravega by pravega.

the class ContainerReadIndexTests method testStorageReadTransactionNoCache.

// region Scenario-based tests
/**
 * Tests the following Scenario, where the ReadIndex would either read from a bad offset or fail with an invalid offset
 * when reading in certain conditions:
 * * A segment has a transaction, which has N bytes written to it.
 * * The transaction is merged into its parent segment at offset M > N.
 * * At least one byte of the transaction is evicted from the cache
 * * A read is issued to the parent segment for that byte that was evicted
 * * The ReadIndex is supposed to issue a Storage Read with an offset inside the transaction range (so translate
 * from the parent's offset to the transaction's offset). However, after the read, it is supposed to look like the
 * data was read from the parent segment, so it should not expose the adjusted offset at all.
 * <p>
 * This very specific unit test is a result of a regression found during testing.
 */
@Test
public void testStorageReadTransactionNoCache() throws Exception {
    CachePolicy cachePolicy = new CachePolicy(1, Duration.ZERO, Duration.ofMillis(1));
    @Cleanup TestContext context = new TestContext(DEFAULT_CONFIG, cachePolicy);
    // Create parent segment and one transaction
    long parentId = createSegment(0, context);
    long transactionId = createTransaction(1, context);
    createSegmentsInStorage(context);
    ByteArrayOutputStream writtenStream = new ByteArrayOutputStream();
    // Write something to the transaction, and make sure it also makes its way to Storage.
    UpdateableSegmentMetadata parentMetadata = context.metadata.getStreamSegmentMetadata(parentId);
    UpdateableSegmentMetadata transactionMetadata = context.metadata.getStreamSegmentMetadata(transactionId);
    ByteArraySegment transactionWriteData = getAppendData(transactionMetadata.getName(), transactionId, 0, 0);
    appendSingleWrite(transactionId, transactionWriteData, context);
    val handle = context.storage.openWrite(transactionMetadata.getName()).join();
    context.storage.write(handle, 0, transactionWriteData.getReader(), transactionWriteData.getLength(), TIMEOUT).join();
    transactionMetadata.setStorageLength(transactionMetadata.getLength());
    // Write some data to the parent, and make sure it is more than what we write to the transaction (hence the 10).
    for (int i = 0; i < 10; i++) {
        ByteArraySegment parentWriteData = getAppendData(parentMetadata.getName(), parentId, i, i);
        appendSingleWrite(parentId, parentWriteData, context);
        parentWriteData.copyTo(writtenStream);
    }
    // Seal & Begin-merge the transaction (do not seal in storage).
    transactionMetadata.markSealed();
    long mergeOffset = parentMetadata.getLength();
    parentMetadata.setLength(mergeOffset + transactionMetadata.getLength());
    context.readIndex.beginMerge(parentId, mergeOffset, transactionId);
    transactionMetadata.markMerged();
    transactionWriteData.copyTo(writtenStream);
    // Clear the cache.
    boolean evicted = context.cacheManager.applyCachePolicy();
    Assert.assertTrue("Expected an eviction.", evicted);
    // Issue read from the parent.
    ReadResult rr = context.readIndex.read(parentId, mergeOffset, transactionWriteData.getLength(), TIMEOUT);
    Assert.assertTrue("Parent Segment read indicates no data available.", rr.hasNext());
    ByteArrayOutputStream readStream = new ByteArrayOutputStream();
    long expectedOffset = mergeOffset;
    while (rr.hasNext()) {
        ReadResultEntry entry = rr.next();
        Assert.assertEquals("Unexpected offset for read result entry.", expectedOffset, entry.getStreamSegmentOffset());
        Assert.assertEquals("Served read result entry is not from storage.", ReadResultEntryType.Storage, entry.getType());
        // Request contents and store for later use.
        entry.requestContent(TIMEOUT);
        BufferView contents = entry.getContent().get(TIMEOUT.toMillis(), TimeUnit.MILLISECONDS);
        contents.copyTo(readStream);
        expectedOffset += contents.getLength();
    }
    byte[] readData = readStream.toByteArray();
    Assert.assertArrayEquals("Unexpected data read back.", transactionWriteData.getCopy(), readData);
}

Example 2 with CachePolicy

use of io.pravega.segmentstore.server.CachePolicy in project pravega by pravega.

the class ContainerReadIndexTests method testCacheEviction.

/**
 * Tests the ability to evict entries from the ReadIndex under various conditions:
 * * If an entry is aged out
 * * If an entry is pushed out because of cache space pressure.
 *
 * This also verifies that certain entries, such as RedirectReadIndexEntries and entries after the Storage Offset are
 * not removed.
 *
 * The way this test goes is as follows (it's pretty subtle, because there aren't many ways to hook into the ReadIndex and see what it's doing)
 * 1. It creates a bunch of segments, and populates them in storage (each) up to offset N/2-1 (this is called pre-storage)
 * 2. It populates the ReadIndex for each of those segments from offset N/2 to offset N-1 (this is called post-storage)
 * 3. It loads all the data from Storage into the ReadIndex, in entries of size equal to those already loaded in step #2.
 * 3a. At this point, all the entries added in step #2 have Generations 0..A/4-1, and step #3 have generations A/4..A-1
 * 4. Append more data at the end. This forces the generation to increase to 1.25A.
 * 4a. Nothing should be evicted from the cache now, since the earliest items are all post-storage.
 * 5. We 'touch' (read) the first 1/3 of pre-storage entries (offsets 0..N/4).
 * 5a. At this point, those entries (offsets 0..N/6) will have the newest generations (1.25A..1.5A)
 * 6. We append more data (equivalent to the data we touched)
 * 6a. Nothing should be evicted, since those generations that were just eligible for removal were touched and bumped up.
 * 7. We forcefully increase the current generation by 1 (without touching the ReadIndex)
 * 7a. At this point, we expect all the pre-storage items, except the touched ones, to be evicted. This is generations 0.25A-0.75A.
 * 8. Update the metadata and indicate that all the post-storage entries are now pre-storage and bump the generation by 0.75A.
 * 8a. At this point, we expect all former post-storage items and pre-storage items to be evicted (in this order).
 * <p>
 * The final order of eviction (in terms of offsets, for each segment), is:
 * * 0.25N-0.75N, 0.75N..N, N..1.25N, 0..0.25N, 1.25N..1.5N (remember that we added quite a bunch of items after the initial run).
 */
@Test
@SuppressWarnings("checkstyle:CyclomaticComplexity")
public void testCacheEviction() throws Exception {
    // Create a CachePolicy with a set number of generations and a known max size.
    // Each generation contains exactly one entry, so the number of generations is also the number of entries.
    // We append one byte at each time. This allows us to test edge cases as well by having the finest precision when
    // it comes to selecting which bytes we want evicted and which kept.
    final int appendSize = 1;
    // This also doubles as number of generations (each generation, we add one append for each segment).
    final int entriesPerSegment = 100;
    final int cacheMaxSize = SEGMENT_COUNT * entriesPerSegment * appendSize;
    // 25% of the entries are beyond the StorageOffset
    final int postStorageEntryCount = entriesPerSegment / 4;
    // 75% of the entries are before the StorageOffset.
    final int preStorageEntryCount = entriesPerSegment - postStorageEntryCount;
    CachePolicy cachePolicy = new CachePolicy(cacheMaxSize, 1.0, 1.0, Duration.ofMillis(1000 * 2 * entriesPerSegment), Duration.ofMillis(1000));
    // To properly test this, we want predictable storage reads.
    ReadIndexConfig config = ReadIndexConfig.builder().with(ReadIndexConfig.STORAGE_READ_ALIGNMENT, appendSize).build();
    ArrayList<Integer> removedEntries = new ArrayList<>();
    @Cleanup TestContext context = new TestContext(config, cachePolicy);
    // To ease our testing, we disable appends and instruct the TestCache to report the same value for UsedBytes as it
    // has for StoredBytes. This shields us from having to know internal details about the layout of the cache.
    context.cacheStorage.usedBytesSameAsStoredBytes = true;
    context.cacheStorage.disableAppends = true;
    // Record every cache removal.
    context.cacheStorage.deleteCallback = removedEntries::add;
    // Create the segments (metadata + storage).
    ArrayList<Long> segmentIds = createSegments(context);
    createSegmentsInStorage(context);
    // Populate the Storage with appropriate data.
    byte[] preStorageData = new byte[preStorageEntryCount * appendSize];
    for (long segmentId : segmentIds) {
        UpdateableSegmentMetadata sm = context.metadata.getStreamSegmentMetadata(segmentId);
        val handle = context.storage.openWrite(sm.getName()).join();
        context.storage.write(handle, 0, new ByteArrayInputStream(preStorageData), preStorageData.length, TIMEOUT).join();
        sm.setStorageLength(preStorageData.length);
        sm.setLength(preStorageData.length);
    }
    val cacheMappings = new HashMap<Integer, SegmentOffset>();
    // Callback that appends one entry at the end of the given segment id.
    Consumer<Long> appendOneEntry = segmentId -> {
        UpdateableSegmentMetadata sm = context.metadata.getStreamSegmentMetadata(segmentId);
        byte[] data = new byte[appendSize];
        long offset = sm.getLength();
        sm.setLength(offset + data.length);
        try {
            context.cacheStorage.insertCallback = address -> cacheMappings.put(address, new SegmentOffset(segmentId, offset));
            context.readIndex.append(segmentId, offset, new ByteArraySegment(data));
        } catch (StreamSegmentNotExistsException ex) {
            throw new CompletionException(ex);
        }
    };
    // Populate the ReadIndex with the Append entries (post-StorageOffset)
    for (int i = 0; i < postStorageEntryCount; i++) {
        segmentIds.forEach(appendOneEntry);
        // Each time we make a round of appends (one per segment), we increment the generation in the CacheManager.
        context.cacheManager.applyCachePolicy();
    }
    // Read all the data from Storage, making sure we carefully associate them with the proper generation.
    for (int i = 0; i < preStorageEntryCount; i++) {
        long offset = i * appendSize;
        for (long segmentId : segmentIds) {
            @Cleanup ReadResult result = context.readIndex.read(segmentId, offset, appendSize, TIMEOUT);
            ReadResultEntry resultEntry = result.next();
            Assert.assertEquals("Unexpected type of ReadResultEntry when trying to load up data into the ReadIndex Cache.", ReadResultEntryType.Storage, resultEntry.getType());
            CompletableFuture<Void> insertedInCache = new CompletableFuture<>();
            context.cacheStorage.insertCallback = address -> {
                cacheMappings.put(address, new SegmentOffset(segmentId, offset));
                insertedInCache.complete(null);
            };
            resultEntry.requestContent(TIMEOUT);
            BufferView contents = resultEntry.getContent().get(TIMEOUT.toMillis(), TimeUnit.MILLISECONDS);
            Assert.assertFalse("Not expecting more data to be available for reading.", result.hasNext());
            Assert.assertEquals("Unexpected ReadResultEntry length when trying to load up data into the ReadIndex Cache.", appendSize, contents.getLength());
            // Wait for the entry to be inserted into the cache before moving on.
            insertedInCache.get(TIMEOUT.toMillis(), TimeUnit.MILLISECONDS);
        }
        context.cacheManager.applyCachePolicy();
    }
    Assert.assertEquals("Not expecting any removed Cache entries at this point (cache is not full).", 0, removedEntries.size());
    // Append more data (equivalent to all post-storage entries), and verify that NO entries are being evicted (we cannot evict post-storage entries).
    for (int i = 0; i < postStorageEntryCount; i++) {
        segmentIds.forEach(appendOneEntry);
        context.cacheManager.applyCachePolicy();
    }
    Assert.assertEquals("Not expecting any removed Cache entries at this point (only eligible entries were post-storage).", 0, removedEntries.size());
    // 'Touch' the first few entries read from storage. This should move them to the back of the queue (they won't be the first ones to be evicted).
    int touchCount = preStorageEntryCount / 3;
    for (int i = 0; i < touchCount; i++) {
        long offset = i * appendSize;
        for (long segmentId : segmentIds) {
            @Cleanup ReadResult result = context.readIndex.read(segmentId, offset, appendSize, TIMEOUT);
            ReadResultEntry resultEntry = result.next();
            Assert.assertEquals("Unexpected type of ReadResultEntry when trying to load up data into the ReadIndex Cache.", ReadResultEntryType.Cache, resultEntry.getType());
        }
    }
    // Append more data (equivalent to the amount of data we 'touched'), and verify that the entries we just touched are not being removed..
    for (int i = 0; i < touchCount; i++) {
        segmentIds.forEach(appendOneEntry);
        context.cacheManager.applyCachePolicy();
    }
    Assert.assertEquals("Not expecting any removed Cache entries at this point (we touched old entries and they now have the newest generation).", 0, removedEntries.size());
    // Increment the generations so that we are caught up to just before the generation where the "touched" items now live.
    context.cacheManager.applyCachePolicy();
    // We expect all but the 'touchCount' pre-Storage entries to be removed.
    int expectedRemovalCount = (preStorageEntryCount - touchCount) * SEGMENT_COUNT;
    Assert.assertEquals("Unexpected number of removed entries after having forced out all pre-storage entries.", expectedRemovalCount, removedEntries.size());
    // Now update the metadata and indicate that all the post-storage data has been moved to storage.
    segmentIds.forEach(segmentId -> {
        UpdateableSegmentMetadata sm = context.metadata.getStreamSegmentMetadata(segmentId);
        sm.setStorageLength(sm.getLength());
    });
    // We add one artificial entry, which we'll be touching forever and ever; this forces the CacheManager to
    // update its current generation every time. We will be ignoring this entry for our test.
    SegmentMetadata readSegment = context.metadata.getStreamSegmentMetadata(segmentIds.get(0));
    appendOneEntry.accept(readSegment.getId());
    // Now evict everything (whether by size of by aging out).
    for (int i = 0; i < cachePolicy.getMaxGenerations(); i++) {
        @Cleanup ReadResult result = context.readIndex.read(readSegment.getId(), readSegment.getLength() - appendSize, appendSize, TIMEOUT);
        result.next();
        context.cacheManager.applyCachePolicy();
    }
    int expectedRemovalCountPerSegment = entriesPerSegment + touchCount + postStorageEntryCount;
    int expectedTotalRemovalCount = SEGMENT_COUNT * expectedRemovalCountPerSegment;
    Assert.assertEquals("Unexpected number of removed entries after having forced out all the entries.", expectedTotalRemovalCount, removedEntries.size());
    // Finally, verify that the evicted items are in the correct order (for each segment). See this test's description for details.
    for (long segmentId : segmentIds) {
        List<SegmentOffset> segmentRemovedKeys = removedEntries.stream().map(cacheMappings::get).filter(e -> e.segmentId == segmentId).collect(Collectors.toList());
        Assert.assertEquals("Unexpected number of removed entries for segment " + segmentId, expectedRemovalCountPerSegment, segmentRemovedKeys.size());
        // The correct order of eviction (N=entriesPerSegment) is: 0.25N-0.75N, 0.75N..N, N..1.25N, 0..0.25N, 1.25N..1.5N.
        // This is equivalent to the following tests
        // 0.25N-1.25N
        checkOffsets(segmentRemovedKeys, segmentId, 0, entriesPerSegment, entriesPerSegment * appendSize / 4, appendSize);
        // 0..0.25N
        checkOffsets(segmentRemovedKeys, segmentId, entriesPerSegment, entriesPerSegment / 4, 0, appendSize);
        // 1.25N..1.5N
        checkOffsets(segmentRemovedKeys, segmentId, entriesPerSegment + entriesPerSegment / 4, entriesPerSegment / 4, (int) (entriesPerSegment * appendSize * 1.25), appendSize);
    }
}

Example 3 with CachePolicy

use of io.pravega.segmentstore.server.CachePolicy in project pravega by pravega.

the class ContainerReadIndexTests method testTruncate.

/**
 * Tests a scenario of truncation that does not happen concurrently with reading (segments are pre-truncated).
 */
@Test
public void testTruncate() throws Exception {
    @Cleanup TestContext context = new TestContext(DEFAULT_CONFIG, new CachePolicy(Long.MAX_VALUE, Duration.ofMillis(1000000), Duration.ofMillis(10000)));
    ArrayList<Long> segmentIds = createSegments(context);
    HashMap<Long, ByteArrayOutputStream> segmentContents = new HashMap<>();
    appendData(segmentIds, segmentContents, context);
    // Truncate all segments at their mid-points.
    for (int i = 0; i < segmentIds.size(); i++) {
        val sm = context.metadata.getStreamSegmentMetadata(segmentIds.get(i));
        sm.setStartOffset(sm.getLength() / 2);
        if (i % 2 == 0) {
            sm.setStorageLength(sm.getStartOffset());
        } else {
            sm.setStorageLength(sm.getStartOffset() / 2);
        }
    }
    // Check all the appended data. This includes verifying access to already truncated offsets.
    checkReadIndex("PostTruncate", segmentContents, context);
    checkReadIndexDirect(segmentContents, context);
    // Verify that truncated data is eligible for eviction, by checking that at least one Cache Entry is being removed.
    for (long segmentId : segmentIds) {
        val sm = context.metadata.getStreamSegmentMetadata(segmentId);
        // We need to set this in order to verify cache evictions.
        sm.setStorageLength(sm.getLength());
    }
    HashSet<Integer> deletedEntries = new HashSet<>();
    context.cacheStorage.deleteCallback = deletedEntries::add;
    context.cacheManager.applyCachePolicy();
    AssertExtensions.assertGreaterThan("Expected at least one cache entry to be removed.", 0, deletedEntries.size());
}

Example 4 with CachePolicy

use of io.pravega.segmentstore.server.CachePolicy in project pravega by pravega.

the class ContainerReadIndexTests method testConcurrentReadTransactionStorageMerge.

/**
 * Tests the following scenario, where the Read Index has a read from a portion in a parent segment where a transaction
 * was just merged (fully in storage), but the read request might result in either an ObjectClosedException or
 * StreamSegmentNotExistsException:
 * * A Parent Segment has a Transaction with some data in it, and at least 1 byte of data not in cache.
 * * The Transaction is begin-merged in the parent (Tier 1 only).
 * * A Read Request is issued to the Parent for the range of data from the Transaction, which includes the 1 byte not in cache.
 * * The Transaction is fully merged (Tier 2).
 * * The Read Request is invoked and its content requested. This should correctly retrieve the data from the Parent
 * Segment in Storage, and not attempt to access the now-defunct Transaction segment.
 */
@Test
public void testConcurrentReadTransactionStorageMerge() throws Exception {
    CachePolicy cachePolicy = new CachePolicy(1, Duration.ZERO, Duration.ofMillis(1));
    @Cleanup TestContext context = new TestContext(DEFAULT_CONFIG, cachePolicy);
    // Create parent segment and one transaction
    long parentId = createSegment(0, context);
    long transactionId = createTransaction(1, context);
    createSegmentsInStorage(context);
    ByteArraySegment writeData = getAppendData(context.metadata.getStreamSegmentMetadata(transactionId).getName(), transactionId, 0, 0);
    ReadResultEntry entry = setupMergeRead(parentId, transactionId, writeData.getCopy(), context);
    context.readIndex.completeMerge(parentId, transactionId);
    BufferView contents = entry.getContent().get(TIMEOUT.toMillis(), TimeUnit.MILLISECONDS);
    byte[] readData = contents.getCopy();
    Assert.assertArrayEquals("Unexpected data read from parent segment.", writeData.getCopy(), readData);
}

Example 5 with CachePolicy

use of io.pravega.segmentstore.server.CachePolicy in project pravega by pravega.

the class ContainerReadIndexTests method testStorageReadsConcurrent.

private void testStorageReadsConcurrent(int offsetDeltaBetweenReads, int extraAllowedStorageReads, BiConsumerWithException<TestContext, UpdateableSegmentMetadata> executeBetweenReads, BiConsumerWithException<TestContext, UpdateableSegmentMetadata> finalCheck) throws Exception {
    val maxAllowedStorageReads = 2 + extraAllowedStorageReads;
    // Set a cache size big enough to prevent the Cache Manager from enabling "essential-only" mode due to over-utilization.
    val cachePolicy = new CachePolicy(10000, 0.01, 1.0, Duration.ofMillis(10), Duration.ofMillis(10));
    @Cleanup TestContext context = new TestContext(DEFAULT_CONFIG, cachePolicy);
    // Create the segment
    val segmentId = createSegment(0, context);
    val metadata = context.metadata.getStreamSegmentMetadata(segmentId);
    context.storage.create(metadata.getName(), TIMEOUT).join();
    // Append some data to the Read Index.
    val dataInStorage = getAppendData(metadata.getName(), segmentId, 0, 0);
    metadata.setLength(dataInStorage.getLength());
    context.readIndex.append(segmentId, 0, dataInStorage);
    // Then write to Storage.
    context.storage.openWrite(metadata.getName()).thenCompose(handle -> context.storage.write(handle, 0, dataInStorage.getReader(), dataInStorage.getLength(), TIMEOUT)).join();
    metadata.setStorageLength(dataInStorage.getLength());
    // Then evict it from the cache.
    boolean evicted = context.cacheManager.applyCachePolicy();
    Assert.assertTrue("Expected an eviction.", evicted);
    @Cleanup("release") val firstReadBlocker = new ReusableLatch();
    @Cleanup("release") val firstRead = new ReusableLatch();
    @Cleanup("release") val secondReadBlocker = new ReusableLatch();
    @Cleanup("release") val secondRead = new ReusableLatch();
    val cacheInsertCount = new AtomicInteger();
    context.cacheStorage.insertCallback = address -> {
        if (cacheInsertCount.incrementAndGet() > 1) {
            Assert.fail("Too many cache inserts.");
        }
    };
    val storageReadCount = new AtomicInteger();
    context.storage.setReadInterceptor((segment, wrappedStorage) -> {
        int readCount = storageReadCount.incrementAndGet();
        if (readCount == 1) {
            firstRead.release();
            Exceptions.handleInterrupted(firstReadBlocker::await);
        } else if (readCount == 2) {
            secondRead.release();
            Exceptions.handleInterrupted(secondReadBlocker::await);
        } else if (readCount > maxAllowedStorageReads) {
            Assert.fail("Too many storage reads. Max allowed = " + maxAllowedStorageReads);
        }
    });
    // Initiate the first Storage Read.
    val read1Result = context.readIndex.read(segmentId, 0, dataInStorage.getLength(), TIMEOUT);
    val read1Data = new byte[dataInStorage.getLength()];
    val read1Future = CompletableFuture.runAsync(() -> read1Result.readRemaining(read1Data, TIMEOUT), executorService());
    // Wait for it to process.
    firstRead.await();
    // Initiate the second storage read.
    val read2Length = dataInStorage.getLength() - offsetDeltaBetweenReads;
    val read2Result = context.readIndex.read(segmentId, offsetDeltaBetweenReads, read2Length, TIMEOUT);
    val read2Data = new byte[read2Length];
    val read2Future = CompletableFuture.runAsync(() -> read2Result.readRemaining(read2Data, TIMEOUT), executorService());
    secondRead.await();
    // Unblock the first Storage Read and wait for it to complete.
    firstReadBlocker.release();
    read1Future.get(TIMEOUT.toMillis(), TimeUnit.MILLISECONDS);
    // Wait for the data from the first read to be fully added to the cache. Without this the subsequent append will not write to this entry.
    TestUtils.await(() -> {
        try {
            return context.readIndex.read(0, 0, dataInStorage.getLength(), TIMEOUT).next().getType() == ReadResultEntryType.Cache;
        } catch (StreamSegmentNotExistsException ex) {
            throw new CompletionException(ex);
        }
    }, 10, TIMEOUT.toMillis());
    // If there's anything to do between the two reads, do it now.
    executeBetweenReads.accept(context, metadata);
    // Unblock second Storage Read.
    secondReadBlocker.release();
    read2Future.get(TIMEOUT.toMillis(), TimeUnit.MILLISECONDS);
    // Perform final check.
    finalCheck.accept(context, metadata);
    Assert.assertEquals("Unexpected number of storage reads.", maxAllowedStorageReads, storageReadCount.get());
    Assert.assertEquals("Unexpected number of cache inserts.", 1, cacheInsertCount.get());
}