Examples with COMMAND_BLOCK org.apache.hudi.common.table.log.block.HoodieLogBlock.HoodieLogBlockType.COMMAND_BLOCK used on opensource projects

Example 1 with COMMAND_BLOCK

use of org.apache.hudi.common.table.log.block.HoodieLogBlock.HoodieLogBlockType.COMMAND_BLOCK in project hudi by apache.

the class AbstractHoodieLogRecordReader method scan.

public synchronized void scan(Option<List<String>> keys) {
    currentInstantLogBlocks = new ArrayDeque<>();
    progress = 0.0f;
    totalLogFiles = new AtomicLong(0);
    totalRollbacks = new AtomicLong(0);
    totalCorruptBlocks = new AtomicLong(0);
    totalLogBlocks = new AtomicLong(0);
    totalLogRecords = new AtomicLong(0);
    HoodieLogFormatReader logFormatReaderWrapper = null;
    HoodieTimeline commitsTimeline = this.hoodieTableMetaClient.getCommitsTimeline();
    HoodieTimeline completedInstantsTimeline = commitsTimeline.filterCompletedInstants();
    HoodieTimeline inflightInstantsTimeline = commitsTimeline.filterInflights();
    try {
        // Get the key field based on populate meta fields config
        // and the table type
        final String keyField = getKeyField();
        // Iterate over the paths
        logFormatReaderWrapper = new HoodieLogFormatReader(fs, logFilePaths.stream().map(logFile -> new HoodieLogFile(new Path(logFile))).collect(Collectors.toList()), readerSchema, readBlocksLazily, reverseReader, bufferSize, !enableFullScan, keyField);
        Set<HoodieLogFile> scannedLogFiles = new HashSet<>();
        while (logFormatReaderWrapper.hasNext()) {
            HoodieLogFile logFile = logFormatReaderWrapper.getLogFile();
            LOG.info("Scanning log file " + logFile);
            scannedLogFiles.add(logFile);
            totalLogFiles.set(scannedLogFiles.size());
            // Use the HoodieLogFileReader to iterate through the blocks in the log file
            HoodieLogBlock logBlock = logFormatReaderWrapper.next();
            final String instantTime = logBlock.getLogBlockHeader().get(INSTANT_TIME);
            totalLogBlocks.incrementAndGet();
            if (logBlock.getBlockType() != CORRUPT_BLOCK && !HoodieTimeline.compareTimestamps(logBlock.getLogBlockHeader().get(INSTANT_TIME), HoodieTimeline.LESSER_THAN_OR_EQUALS, this.latestInstantTime)) {
                // hit a block with instant time greater than should be processed, stop processing further
                break;
            }
            if (logBlock.getBlockType() != CORRUPT_BLOCK && logBlock.getBlockType() != COMMAND_BLOCK) {
                if (!completedInstantsTimeline.containsOrBeforeTimelineStarts(instantTime) || inflightInstantsTimeline.containsInstant(instantTime)) {
                    // hit an uncommitted block possibly from a failed write, move to the next one and skip processing this one
                    continue;
                }
                if (instantRange.isPresent() && !instantRange.get().isInRange(instantTime)) {
                    // filter the log block by instant range
                    continue;
                }
            }
            switch(logBlock.getBlockType()) {
                case HFILE_DATA_BLOCK:
                case AVRO_DATA_BLOCK:
                case PARQUET_DATA_BLOCK:
                    LOG.info("Reading a data block from file " + logFile.getPath() + " at instant " + logBlock.getLogBlockHeader().get(INSTANT_TIME));
                    if (isNewInstantBlock(logBlock) && !readBlocksLazily) {
                        // If this is an avro data block belonging to a different commit/instant,
                        // then merge the last blocks and records into the main result
                        processQueuedBlocksForInstant(currentInstantLogBlocks, scannedLogFiles.size(), keys);
                    }
                    // store the current block
                    currentInstantLogBlocks.push(logBlock);
                    break;
                case DELETE_BLOCK:
                    LOG.info("Reading a delete block from file " + logFile.getPath());
                    if (isNewInstantBlock(logBlock) && !readBlocksLazily) {
                        // If this is a delete data block belonging to a different commit/instant,
                        // then merge the last blocks and records into the main result
                        processQueuedBlocksForInstant(currentInstantLogBlocks, scannedLogFiles.size(), keys);
                    }
                    // store deletes so can be rolled back
                    currentInstantLogBlocks.push(logBlock);
                    break;
                case COMMAND_BLOCK:
                    // Consider the following scenario
                    // (Time 0, C1, Task T1) -> Running
                    // (Time 1, C1, Task T1) -> Failed (Wrote either a corrupt block or a correct
                    // DataBlock (B1) with commitTime C1
                    // (Time 2, C1, Task T1.2) -> Running (Task T1 was retried and the attempt number is 2)
                    // (Time 3, C1, Task T1.2) -> Finished (Wrote a correct DataBlock B2)
                    // Now a logFile L1 can have 2 correct Datablocks (B1 and B2) which are the same.
                    // Say, commit C1 eventually failed and a rollback is triggered.
                    // Rollback will write only 1 rollback block (R1) since it assumes one block is
                    // written per ingestion batch for a file but in reality we need to rollback (B1 & B2)
                    // The following code ensures the same rollback block (R1) is used to rollback
                    // both B1 & B2
                    LOG.info("Reading a command block from file " + logFile.getPath());
                    // This is a command block - take appropriate action based on the command
                    HoodieCommandBlock commandBlock = (HoodieCommandBlock) logBlock;
                    String targetInstantForCommandBlock = logBlock.getLogBlockHeader().get(HoodieLogBlock.HeaderMetadataType.TARGET_INSTANT_TIME);
                    switch(// there can be different types of command blocks
                    commandBlock.getType()) {
                        case ROLLBACK_PREVIOUS_BLOCK:
                            // Rollback the last read log block
                            // Get commit time from last record block, compare with targetCommitTime,
                            // rollback only if equal, this is required in scenarios of invalid/extra
                            // rollback blocks written due to failures during the rollback operation itself
                            // and ensures the same rollback block (R1) is used to rollback both B1 & B2 with
                            // same instant_time
                            int numBlocksRolledBack = 0;
                            totalRollbacks.incrementAndGet();
                            while (!currentInstantLogBlocks.isEmpty()) {
                                HoodieLogBlock lastBlock = currentInstantLogBlocks.peek();
                                // handle corrupt blocks separately since they may not have metadata
                                if (lastBlock.getBlockType() == CORRUPT_BLOCK) {
                                    LOG.info("Rolling back the last corrupted log block read in " + logFile.getPath());
                                    currentInstantLogBlocks.pop();
                                    numBlocksRolledBack++;
                                } else if (targetInstantForCommandBlock.contentEquals(lastBlock.getLogBlockHeader().get(INSTANT_TIME))) {
                                    // rollback last data block or delete block
                                    LOG.info("Rolling back the last log block read in " + logFile.getPath());
                                    currentInstantLogBlocks.pop();
                                    numBlocksRolledBack++;
                                } else if (!targetInstantForCommandBlock.contentEquals(currentInstantLogBlocks.peek().getLogBlockHeader().get(INSTANT_TIME))) {
                                    // invalid or extra rollback block
                                    LOG.warn("TargetInstantTime " + targetInstantForCommandBlock + " invalid or extra rollback command block in " + logFile.getPath());
                                    break;
                                } else {
                                    // this should not happen ideally
                                    LOG.warn("Unable to apply rollback command block in " + logFile.getPath());
                                }
                            }
                            LOG.info("Number of applied rollback blocks " + numBlocksRolledBack);
                            break;
                        default:
                            throw new UnsupportedOperationException("Command type not yet supported.");
                    }
                    break;
                case CORRUPT_BLOCK:
                    LOG.info("Found a corrupt block in " + logFile.getPath());
                    totalCorruptBlocks.incrementAndGet();
                    // If there is a corrupt block - we will assume that this was the next data block
                    currentInstantLogBlocks.push(logBlock);
                    break;
                default:
                    throw new UnsupportedOperationException("Block type not supported yet");
            }
        }
        // merge the last read block when all the blocks are done reading
        if (!currentInstantLogBlocks.isEmpty()) {
            LOG.info("Merging the final data blocks");
            processQueuedBlocksForInstant(currentInstantLogBlocks, scannedLogFiles.size(), keys);
        }
        // Done
        progress = 1.0f;
    } catch (IOException e) {
        LOG.error("Got IOException when reading log file", e);
        throw new HoodieIOException("IOException when reading log file ", e);
    } catch (Exception e) {
        LOG.error("Got exception when reading log file", e);
        throw new HoodieException("Exception when reading log file ", e);
    } finally {
        try {
            if (null != logFormatReaderWrapper) {
                logFormatReaderWrapper.close();
            }
        } catch (IOException ioe) {
            // Eat exception as we do not want to mask the original exception that can happen
            LOG.error("Unable to close log format reader", ioe);
        }
    }
}