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PARQUET-669: allow reading footers from provided file listing and streams #357

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PARQUET-669: allow reading footers from provided file listing and streams #357

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28 changes: 18 additions & 10 deletions parquet-hadoop/src/main/java/org/apache/parquet/hadoop/ParquetFileReader.java
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Original file line number Diff line number Diff line change
Expand Up @@ -434,22 +434,30 @@ public static final ParquetMetadata readFooter(Configuration configuration, File
FileSystem fileSystem = file.getPath().getFileSystem(configuration);
FSDataInputStream in = fileSystem.open(file.getPath());
try {
return readFooter(file, in, filter);
return readFooter(file.getLen(), file.getPath().toString(), in, filter);
} finally {
in.close();
}
}

private static final ParquetMetadata readFooter(FileStatus file, FSDataInputStream f, MetadataFilter filter) throws IOException {
long l = file.getLen();
/**
* Reads the meta data block in the footer of the file using provided input stream
* @param fileLen length of the file
* @param filePath file location
* @param f input stream for the file
* @param filter the filter to apply to row groups
* @return the metadata blocks in the footer
* @throws IOException if an error occurs while reading the file
*/
public static final ParquetMetadata readFooter(long fileLen, String filePath, FSDataInputStream f, MetadataFilter filter) throws IOException {
if (Log.DEBUG) {
LOG.debug("File length " + l);
LOG.debug("File length " + fileLen);
}
int FOOTER_LENGTH_SIZE = 4;
if (l < MAGIC.length + FOOTER_LENGTH_SIZE + MAGIC.length) { // MAGIC + data + footer + footerIndex + MAGIC
throw new RuntimeException(file.getPath() + " is not a Parquet file (too small)");
if (fileLen < MAGIC.length + FOOTER_LENGTH_SIZE + MAGIC.length) { // MAGIC + data + footer + footerIndex + MAGIC
throw new RuntimeException(filePath + " is not a Parquet file (too small)");
}
long footerLengthIndex = l - FOOTER_LENGTH_SIZE - MAGIC.length;
long footerLengthIndex = fileLen - FOOTER_LENGTH_SIZE - MAGIC.length;
if (Log.DEBUG) {
LOG.debug("reading footer index at " + footerLengthIndex);
}
Expand All @@ -459,7 +467,7 @@ private static final ParquetMetadata readFooter(FileStatus file, FSDataInputStre
byte[] magic = new byte[MAGIC.length];
f.readFully(magic);
if (!Arrays.equals(MAGIC, magic)) {
throw new RuntimeException(file.getPath() + " is not a Parquet file. expected magic number at tail " + Arrays.toString(MAGIC) + " but found " + Arrays.toString(magic));
throw new RuntimeException(filePath + " is not a Parquet file. expected magic number at tail " + Arrays.toString(MAGIC) + " but found " + Arrays.toString(magic));
}
long footerIndex = footerLengthIndex - footerLength;
if (Log.DEBUG) {
Expand Down Expand Up @@ -555,7 +563,7 @@ public ParquetFileReader(Configuration conf, Path file, MetadataFilter filter) t
FileSystem fs = file.getFileSystem(conf);
this.fileStatus = fs.getFileStatus(file);
this.f = fs.open(file);
this.footer = readFooter(fileStatus, f, filter);
this.footer = readFooter(fileStatus.getLen(), fileStatus.getPath().toString(), f, filter);
this.fileMetaData = footer.getFileMetaData();
this.blocks = footer.getBlocks();
for (ColumnDescriptor col : footer.getFileMetaData().getSchema().getColumns()) {
Expand Down Expand Up @@ -594,7 +602,7 @@ public ParquetMetadata getFooter() {
if (footer == null) {
try {
// don't read the row groups because this.blocks is always set
this.footer = readFooter(fileStatus, f, SKIP_ROW_GROUPS);
this.footer = readFooter(fileStatus.getLen(), fileStatus.getPath().toString(), f, SKIP_ROW_GROUPS);
} catch (IOException e) {
throw new ParquetDecodingException("Unable to read file footer", e);
}
Expand Down