Examples with MetadataReader io.prestosql.orc.metadata.MetadataReader used on opensource projects

Example 1 with MetadataReader

use of io.prestosql.orc.metadata.MetadataReader in project hetu-core by openlookeng.

the class OrcFileTail method readFrom.

public static OrcFileTail readFrom(OrcDataSource orcDataSource, Optional<OrcWriteValidation> writeValidation) throws IOException {
    OrcFileTail orcFileTail = new OrcFileTail();
    // 
    // Read the file tail:
    // 
    // variable: Footer
    // variable: Metadata
    // variable: PostScript - contains length of footer and metadata
    // 1 byte: postScriptSize
    // figure out the size of the file using the option or filesystem
    long size = orcDataSource.getSize();
    if (size <= PostScript.MAGIC.length()) {
        throw new OrcCorruptionException(orcDataSource.getId(), "Invalid file size %s", size);
    }
    // Read the tail of the file
    int expectedBufferSize = toIntExact(min(size, EXPECTED_FOOTER_SIZE));
    Slice buffer = orcDataSource.readFully(size - expectedBufferSize, expectedBufferSize);
    // get length of PostScript - last byte of the file
    int postScriptSize = buffer.getUnsignedByte(buffer.length() - SIZE_OF_BYTE);
    if (postScriptSize >= buffer.length()) {
        throw new OrcCorruptionException(orcDataSource.getId(), "Invalid postscript length %s", postScriptSize);
    }
    MetadataReader metadataReader = new ExceptionWrappingMetadataReader(orcDataSource.getId(), new OrcMetadataReader());
    // decode the post script
    try {
        orcFileTail.postScript = metadataReader.readPostScript(buffer.slice(buffer.length() - SIZE_OF_BYTE - postScriptSize, postScriptSize).getInput());
    } catch (OrcCorruptionException e) {
        // check if this is an ORC file and not an RCFile or something else
        if (!isValidHeaderMagic(orcDataSource)) {
            throw new OrcCorruptionException(orcDataSource.getId(), "Not an ORC file");
        }
        throw e;
    }
    // verify this is a supported version
    checkOrcVersion(orcDataSource, orcFileTail.postScript.getVersion());
    validateWrite(validation -> validation.getVersion().equals(orcFileTail.postScript.getVersion()), writeValidation, orcDataSource, "Unexpected version");
    int bufferSize = toIntExact(orcFileTail.postScript.getCompressionBlockSize());
    // check compression codec is supported
    CompressionKind compressionKind = orcFileTail.postScript.getCompression();
    orcFileTail.decompressor = OrcDecompressor.createOrcDecompressor(orcDataSource.getId(), compressionKind, bufferSize);
    validateWrite(validation -> validation.getCompression() == compressionKind, writeValidation, orcDataSource, "Unexpected compression");
    PostScript.HiveWriterVersion hiveWriterVersion = orcFileTail.postScript.getHiveWriterVersion();
    int footerSize = toIntExact(orcFileTail.postScript.getFooterLength());
    int metadataSize = toIntExact(orcFileTail.postScript.getMetadataLength());
    // check if extra bytes need to be read
    Slice completeFooterSlice;
    int completeFooterSize = footerSize + metadataSize + postScriptSize + SIZE_OF_BYTE;
    if (completeFooterSize > buffer.length()) {
        // initial read was not large enough, so just read again with the correct size
        completeFooterSlice = orcDataSource.readFully(size - completeFooterSize, completeFooterSize);
    } else {
        // footer is already in the bytes in buffer, just adjust position, length
        completeFooterSlice = buffer.slice(buffer.length() - completeFooterSize, completeFooterSize);
    }
    // read metadata
    Slice metadataSlice = completeFooterSlice.slice(0, metadataSize);
    try (InputStream metadataInputStream = new OrcInputStream(OrcChunkLoader.create(orcDataSource.getId(), metadataSlice, orcFileTail.decompressor, newSimpleAggregatedMemoryContext()))) {
        orcFileTail.metadata = metadataReader.readMetadata(hiveWriterVersion, metadataInputStream);
    }
    // read footer
    Slice footerSlice = completeFooterSlice.slice(metadataSize, footerSize);
    try (InputStream footerInputStream = new OrcInputStream(OrcChunkLoader.create(orcDataSource.getId(), footerSlice, orcFileTail.decompressor, newSimpleAggregatedMemoryContext()))) {
        orcFileTail.footer = metadataReader.readFooter(hiveWriterVersion, footerInputStream);
    }
    if (orcFileTail.footer.getTypes().size() == 0) {
        throw new OrcCorruptionException(orcDataSource.getId(), "File has no columns");
    }
    validateWrite(validation -> validation.getColumnNames().equals(orcFileTail.footer.getTypes().get(new OrcColumnId(0)).getFieldNames()), writeValidation, orcDataSource, "Unexpected column names");
    validateWrite(validation -> validation.getRowGroupMaxRowCount() == orcFileTail.footer.getRowsInRowGroup(), writeValidation, orcDataSource, "Unexpected rows in group");
    if (writeValidation.isPresent()) {
        writeValidation.get().validateMetadata(orcDataSource.getId(), orcFileTail.footer.getUserMetadata());
        writeValidation.get().validateFileStatistics(orcDataSource.getId(), orcFileTail.footer.getFileStats());
        writeValidation.get().validateStripeStatistics(orcDataSource.getId(), orcFileTail.footer.getStripes(), orcFileTail.metadata.getStripeStatsList());
    }
    return orcFileTail;
}