HBASE-27370 Avoid decompressing blocks when reading from bucket cache… (#4781)

Co-authored-by: Josh Elser <elserj@apache.com>
Signed-off-by: Peter Somogyi <psomogyi@apache.org>
Signed-off-by: Tak Lon (Stephen) Wu <taklwu@apache.org>

Author: wchevreuil

hbase-server/src/main/java/org/apache/hadoop/hbase/io/hfile/HFile.java

@@ -373,6 +373,10 @@ public interface CachingBlockReader {
     HFileBlock readBlock(long offset, long onDiskBlockSize, boolean cacheBlock, final boolean pread,
       final boolean isCompaction, final boolean updateCacheMetrics, BlockType expectedBlockType,
       DataBlockEncoding expectedDataBlockEncoding) throws IOException;
+
+    HFileBlock readBlock(long offset, long onDiskBlockSize, boolean cacheBlock, final boolean pread,
+      final boolean isCompaction, final boolean updateCacheMetrics, BlockType expectedBlockType,
+      DataBlockEncoding expectedDataBlockEncoding, boolean cacheOnly) throws IOException;
   }
 
   /** An interface used by clients to open and iterate an {@link HFile}. */

hbase-server/src/main/java/org/apache/hadoop/hbase/io/hfile/HFilePreadReader.java

@@ -57,7 +57,7 @@ public void run() {
               // next header, will not have happened...so, pass in the onDiskSize gotten from the
               // cached block. This 'optimization' triggers extremely rarely I'd say.
               HFileBlock block = readBlock(offset, onDiskSizeOfNextBlock, /* cacheBlock= */true,
-                /* pread= */true, false, false, null, null);
+                /* pread= */true, false, false, null, null, true);
               try {
                 onDiskSizeOfNextBlock = block.getNextBlockOnDiskSize();
                 offset += block.getOnDiskSizeWithHeader();

hbase-server/src/main/java/org/apache/hadoop/hbase/io/hfile/HFileReaderImpl.java

@@ -1082,7 +1082,7 @@ public void setConf(Configuration conf) {
    * and its encoding vs. {@code expectedDataBlockEncoding}. Unpacks the block as necessary.
    */
   private HFileBlock getCachedBlock(BlockCacheKey cacheKey, boolean cacheBlock, boolean useLock,
-    boolean isCompaction, boolean updateCacheMetrics, BlockType expectedBlockType,
+    boolean updateCacheMetrics, BlockType expectedBlockType,
     DataBlockEncoding expectedDataBlockEncoding) throws IOException {
     // Check cache for block. If found return.
     BlockCache cache = cacheConf.getBlockCache().orElse(null);
@@ -1187,7 +1187,7 @@ public HFileBlock getMetaBlock(String metaBlockName, boolean cacheBlock) throws
 
       cacheBlock &= cacheConf.shouldCacheBlockOnRead(BlockType.META.getCategory());
       HFileBlock cachedBlock =
-        getCachedBlock(cacheKey, cacheBlock, false, true, true, BlockType.META, null);
+        getCachedBlock(cacheKey, cacheBlock, false, true, BlockType.META, null);
       if (cachedBlock != null) {
         assert cachedBlock.isUnpacked() : "Packed block leak.";
         // Return a distinct 'shallow copy' of the block,
@@ -1234,6 +1234,15 @@ private boolean shouldUseHeap(BlockType expectedBlockType) {
   public HFileBlock readBlock(long dataBlockOffset, long onDiskBlockSize, final boolean cacheBlock,
     boolean pread, final boolean isCompaction, boolean updateCacheMetrics,
     BlockType expectedBlockType, DataBlockEncoding expectedDataBlockEncoding) throws IOException {
+    return readBlock(dataBlockOffset, onDiskBlockSize, cacheBlock, pread, isCompaction,
+      updateCacheMetrics, expectedBlockType, expectedDataBlockEncoding, false);
+  }
+
+  @Override
+  public HFileBlock readBlock(long dataBlockOffset, long onDiskBlockSize, final boolean cacheBlock,
+    boolean pread, final boolean isCompaction, boolean updateCacheMetrics,
+    BlockType expectedBlockType, DataBlockEncoding expectedDataBlockEncoding, boolean cacheOnly)
+    throws IOException {
     if (dataBlockIndexReader == null) {
       throw new IOException(path + " block index not loaded");
     }
@@ -1257,17 +1266,18 @@ public HFileBlock readBlock(long dataBlockOffset, long onDiskBlockSize, final bo
     try (TraceScope traceScope = TraceUtil.createTrace("HFileReaderImpl.readBlock")) {
       while (true) {
         // Check cache for block. If found return.
-        if (cacheConf.shouldReadBlockFromCache(expectedBlockType)) {
+        if (cacheConf.shouldReadBlockFromCache(expectedBlockType) && !cacheOnly) {
           if (useLock) {
             lockEntry = offsetLock.getLockEntry(dataBlockOffset);
           }
           // Try and get the block from the block cache. If the useLock variable is true then this
           // is the second time through the loop and it should not be counted as a block cache miss.
-          HFileBlock cachedBlock = getCachedBlock(cacheKey, cacheBlock, useLock, isCompaction,
-            updateCacheMetrics, expectedBlockType, expectedDataBlockEncoding);
+          HFileBlock cachedBlock = getCachedBlock(cacheKey, cacheBlock, useLock, updateCacheMetrics,
+            expectedBlockType, expectedDataBlockEncoding);
           if (cachedBlock != null) {
             if (LOG.isTraceEnabled()) {
-              LOG.trace("From Cache " + cachedBlock);
+              LOG.trace("Block for file {} is coming from Cache {}",
+                Bytes.toString(cachedBlock.getHFileContext().getTableName()), cachedBlock);
             }
             TraceUtil.addTimelineAnnotation("blockCacheHit");
             assert cachedBlock.isUnpacked() : "Packed block leak.";
@@ -1304,14 +1314,30 @@ public HFileBlock readBlock(long dataBlockOffset, long onDiskBlockSize, final bo
         HFileBlock hfileBlock = fsBlockReader.readBlockData(dataBlockOffset, onDiskBlockSize, pread,
           !isCompaction, shouldUseHeap(expectedBlockType));
         validateBlockType(hfileBlock, expectedBlockType);
-        HFileBlock unpacked = hfileBlock.unpack(hfileContext, fsBlockReader);
         BlockType.BlockCategory category = hfileBlock.getBlockType().getCategory();
+        final boolean cacheCompressed = cacheConf.shouldCacheCompressed(category);
+        final boolean cacheOnRead = cacheConf.shouldCacheBlockOnRead(category);
+
+        // Don't need the unpacked block back and we're storing the block in the cache compressed
+        if (cacheOnly && cacheCompressed && cacheOnRead) {
+          LOG.debug("Skipping decompression of block in prefetch");
+          // Cache the block if necessary
+          cacheConf.getBlockCache().ifPresent(cache -> {
+            if (cacheBlock && cacheConf.shouldCacheBlockOnRead(category)) {
+              cache.cacheBlock(cacheKey, hfileBlock, cacheConf.isInMemory());
+            }
+          });
 
+          if (updateCacheMetrics && hfileBlock.getBlockType().isData()) {
+            HFile.DATABLOCK_READ_COUNT.increment();
+          }
+          return hfileBlock;
+        }
+        HFileBlock unpacked = hfileBlock.unpack(hfileContext, fsBlockReader);
         // Cache the block if necessary
         cacheConf.getBlockCache().ifPresent(cache -> {
           if (cacheBlock && cacheConf.shouldCacheBlockOnRead(category)) {
-            cache.cacheBlock(cacheKey,
-              cacheConf.shouldCacheCompressed(category) ? hfileBlock : unpacked,
+            cache.cacheBlock(cacheKey, cacheCompressed ? hfileBlock : unpacked,
               cacheConf.isInMemory());
           }
         });

hbase-server/src/test/java/org/apache/hadoop/hbase/io/hfile/TestHFileBlockIndex.java

@@ -176,6 +176,14 @@ public BlockReaderWrapper(HFileBlock.FSReader realReader) {
     public HFileBlock readBlock(long offset, long onDiskSize, boolean cacheBlock, boolean pread,
       boolean isCompaction, boolean updateCacheMetrics, BlockType expectedBlockType,
       DataBlockEncoding expectedDataBlockEncoding) throws IOException {
+      return readBlock(offset, onDiskSize, cacheBlock, pread, isCompaction, updateCacheMetrics,
+        expectedBlockType, expectedDataBlockEncoding, false);
+    }
+
+    @Override
+    public HFileBlock readBlock(long offset, long onDiskSize, boolean cacheBlock, boolean pread,
+      boolean isCompaction, boolean updateCacheMetrics, BlockType expectedBlockType,
+      DataBlockEncoding expectedDataBlockEncoding, boolean cacheOnly) throws IOException {
       if (offset == prevOffset && onDiskSize == prevOnDiskSize && pread == prevPread) {
         hitCount += 1;
         return prevBlock;

hbase-server/src/test/java/org/apache/hadoop/hbase/io/hfile/TestPrefetch.java

@@ -17,12 +17,16 @@
  */
 package org.apache.hadoop.hbase.io.hfile;
 
+import static org.apache.hadoop.hbase.io.hfile.CacheConfig.CACHE_DATA_BLOCKS_COMPRESSED_KEY;
 import static org.junit.Assert.assertFalse;
 import static org.junit.Assert.assertTrue;
+import static org.junit.Assert.fail;
 
 import java.io.IOException;
 import java.util.Random;
 import java.util.concurrent.ThreadLocalRandom;
+import java.util.function.BiConsumer;
+import java.util.function.BiFunction;
 import org.apache.hadoop.conf.Configuration;
 import org.apache.hadoop.fs.FileSystem;
 import org.apache.hadoop.fs.Path;
@@ -34,6 +38,7 @@
 import org.apache.hadoop.hbase.client.ColumnFamilyDescriptorBuilder;
 import org.apache.hadoop.hbase.fs.HFileSystem;
 import org.apache.hadoop.hbase.io.ByteBuffAllocator;
+import org.apache.hadoop.hbase.io.compress.Compression;
 import org.apache.hadoop.hbase.regionserver.StoreFileWriter;
 import org.apache.hadoop.hbase.testclassification.IOTests;
 import org.apache.hadoop.hbase.testclassification.MediumTests;
@@ -112,36 +117,88 @@ private void readStoreFileLikeScanner(Path storeFilePath) throws Exception {
   }
 
   private void readStoreFile(Path storeFilePath) throws Exception {
+    readStoreFile(storeFilePath, (r, o) -> {
+      HFileBlock block = null;
+      try {
+        block = r.readBlock(o, -1, false, true, false, true, null, null);
+      } catch (IOException e) {
+        fail(e.getMessage());
+      }
+      return block;
+    }, (key, block) -> {
+      boolean isCached = blockCache.getBlock(key, true, false, true) != null;
+      if (
+        block.getBlockType() == BlockType.DATA || block.getBlockType() == BlockType.ROOT_INDEX
+          || block.getBlockType() == BlockType.INTERMEDIATE_INDEX
+      ) {
+        assertTrue(isCached);
+      }
+    });
+  }
+
+  private void readStoreFileCacheOnly(Path storeFilePath) throws Exception {
+    readStoreFile(storeFilePath, (r, o) -> {
+      HFileBlock block = null;
+      try {
+        block = r.readBlock(o, -1, false, true, false, true, null, null, true);
+      } catch (IOException e) {
+        fail(e.getMessage());
+      }
+      return block;
+    }, (key, block) -> {
+      boolean isCached = blockCache.getBlock(key, true, false, true) != null;
+      if (block.getBlockType() == BlockType.DATA) {
+        assertFalse(block.isUnpacked());
+      } else if (
+        block.getBlockType() == BlockType.ROOT_INDEX
+          || block.getBlockType() == BlockType.INTERMEDIATE_INDEX
+      ) {
+        assertTrue(block.isUnpacked());
+      }
+      assertTrue(isCached);
+    });
+  }
+
+  private void readStoreFile(Path storeFilePath,
+    BiFunction<HFile.Reader, Long, HFileBlock> readFunction,
+    BiConsumer<BlockCacheKey, HFileBlock> validationFunction) throws Exception {
     // Open the file
     HFile.Reader reader = HFile.createReader(fs, storeFilePath, cacheConf, true, conf);
 
     while (!reader.prefetchComplete()) {
       // Sleep for a bit
       Thread.sleep(1000);
     }
-
-    // Check that all of the data blocks were preloaded
-    BlockCache blockCache = cacheConf.getBlockCache().get();
     long offset = 0;
     while (offset < reader.getTrailer().getLoadOnOpenDataOffset()) {
-      HFileBlock block = reader.readBlock(offset, -1, false, true, false, true, null, null);
+      HFileBlock block = readFunction.apply(reader, offset);
       BlockCacheKey blockCacheKey = new BlockCacheKey(reader.getName(), offset);
-      boolean isCached = blockCache.getBlock(blockCacheKey, true, false, true) != null;
-      if (
-        block.getBlockType() == BlockType.DATA || block.getBlockType() == BlockType.ROOT_INDEX
-          || block.getBlockType() == BlockType.INTERMEDIATE_INDEX
-      ) {
-        assertTrue(isCached);
-      }
+      validationFunction.accept(blockCacheKey, block);
       offset += block.getOnDiskSizeWithHeader();
     }
   }
 
+  @Test
+  public void testPrefetchCompressed() throws Exception {
+    conf.setBoolean(CACHE_DATA_BLOCKS_COMPRESSED_KEY, true);
+    cacheConf = new CacheConfig(conf, blockCache);
+    HFileContext context = new HFileContextBuilder().withCompression(Compression.Algorithm.GZ)
+      .withBlockSize(DATA_BLOCK_SIZE).build();
+    Path storeFile = writeStoreFile("TestPrefetchCompressed", context);
+    readStoreFileCacheOnly(storeFile);
+    conf.setBoolean(CACHE_DATA_BLOCKS_COMPRESSED_KEY, false);
+
+  }
+
   private Path writeStoreFile(String fname) throws IOException {
-    Path storeFileParentDir = new Path(TEST_UTIL.getDataTestDir(), fname);
     HFileContext meta = new HFileContextBuilder().withBlockSize(DATA_BLOCK_SIZE).build();
+    return writeStoreFile(fname, meta);
+  }
+
+  private Path writeStoreFile(String fname, HFileContext context) throws IOException {
+    Path storeFileParentDir = new Path(TEST_UTIL.getDataTestDir(), fname);
     StoreFileWriter sfw = new StoreFileWriter.Builder(conf, cacheConf, fs)
-      .withOutputDir(storeFileParentDir).withFileContext(meta).build();
+      .withOutputDir(storeFileParentDir).withFileContext(context).build();
     Random rand = ThreadLocalRandom.current();
     final int rowLen = 32;
     for (int i = 0; i < NUM_KV; ++i) {