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/**
* Licensed to the Apache Software Foundation (ASF) under one
* or more contributor license agreements. See the NOTICE file
* distributed with this work for additional information
* regarding copyright ownership. The ASF licenses this file
* to you under the Apache License, Version 2.0 (the
* "License"); you may not use this file except in compliance
* with the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing,
* software distributed under the License is distributed on an
* "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
* KIND, either express or implied. See the License for the
* specific language governing permissions and limitations
* under the License.
*/
package org.apache.metamodel.csv;
import java.io.BufferedReader;
import java.io.BufferedWriter;
import java.io.ByteArrayInputStream;
import java.io.File;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.Reader;
import java.io.UnsupportedEncodingException;
import java.net.URL;
import java.util.List;
import org.apache.metamodel.MetaModelException;
import org.apache.metamodel.QueryPostprocessDataContext;
import org.apache.metamodel.UpdateScript;
import org.apache.metamodel.UpdateSummary;
import org.apache.metamodel.UpdateableDataContext;
import org.apache.metamodel.data.DataSet;
import org.apache.metamodel.data.EmptyDataSet;
import org.apache.metamodel.query.FilterItem;
import org.apache.metamodel.schema.Column;
import org.apache.metamodel.schema.Table;
import org.apache.metamodel.util.FileHelper;
import org.apache.metamodel.util.FileResource;
import org.apache.metamodel.util.Resource;
import org.apache.metamodel.util.ResourceUtils;
import org.apache.metamodel.util.UrlResource;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import com.opencsv.CSVParserBuilder;
import com.opencsv.CSVReader;
import com.opencsv.ICSVParser;
import com.opencsv.RFC4180ParserBuilder;
/**
* DataContext implementation for reading CSV files.
*/
public final class CsvDataContext extends QueryPostprocessDataContext implements UpdateableDataContext {
private static final Logger logger = LoggerFactory.getLogger(CsvDataContext.class);
private final Object WRITE_LOCK = new Object();
private final Resource _resource;
private final CsvConfiguration _configuration;
private final boolean _writable;
/**
* Constructs a CSV DataContext based on a file
*
* The file provided can be either existing or non-existing. In the case of
* non-existing files, a file will be automatically created when a CREATE
* TABLE update is executed on the DataContext.
*
* @param file
* @param configuration
*/
public CsvDataContext(File file, CsvConfiguration configuration) {
if (file == null) {
throw new IllegalArgumentException("File cannot be null");
}
if (configuration == null) {
throw new IllegalArgumentException("CsvConfiguration cannot be null");
}
_resource = new FileResource(file);
_configuration = configuration;
_writable = true;
}
public CsvDataContext(Resource resource, CsvConfiguration configuration) {
if (resource == null) {
throw new IllegalArgumentException("File cannot be null");
}
if (configuration == null) {
throw new IllegalArgumentException("CsvConfiguration cannot be null");
}
_resource = resource;
_configuration = configuration;
_writable = !resource.isReadOnly();
}
/**
* Constructs a CSV DataContext based on a {@link URL}
*
* @param url
* @param configuration
*/
public CsvDataContext(URL url, CsvConfiguration configuration) {
_resource = new UrlResource(url);
_configuration = configuration;
_writable = false;
}
/**
* Constructs a CSV DataContext based on a file
*
* @param file
*/
public CsvDataContext(File file) {
this(file, new CsvConfiguration());
}
/**
* Constructs a CSV DataContext based on an {@link InputStream}
*
* @param inputStream
* @param configuration
*/
public CsvDataContext(InputStream inputStream, CsvConfiguration configuration) {
File file = createFileFromInputStream(inputStream, configuration.getEncoding());
_configuration = configuration;
_writable = false;
_resource = new FileResource(file);
}
/**
* Gets the CSV configuration used
*
* @return a CSV configuration
*/
public CsvConfiguration getConfiguration() {
return _configuration;
}
/**
* Gets the resource that is being read from.
*
* @return
*/
public Resource getResource() {
return _resource;
}
private static File createFileFromInputStream(InputStream inputStream, String encoding) {
final File file;
final File tempDir = FileHelper.getTempDir();
File fileCandidate = null;
boolean usableName = false;
int index = 0;
while (!usableName) {
index++;
fileCandidate = new File(tempDir, "metamodel" + index + ".csv");
usableName = !fileCandidate.exists();
}
file = fileCandidate;
final BufferedWriter writer = FileHelper.getBufferedWriter(file, encoding);
final BufferedReader reader = FileHelper.getBufferedReader(inputStream, encoding);
try {
file.createNewFile();
file.deleteOnExit();
boolean firstLine = true;
for (String line = reader.readLine(); line != null; line = reader.readLine()) {
if (firstLine) {
firstLine = false;
} else {
writer.write('\n');
}
writer.write(line);
}
} catch (IOException e) {
throw new IllegalStateException(e);
} finally {
FileHelper.safeClose(writer, reader);
}
return file;
}
@Override
protected Number executeCountQuery(Table table, List whereItems, boolean functionApproximationAllowed) {
if (!functionApproximationAllowed) {
return null;
}
if (whereItems != null && !whereItems.isEmpty()) {
return null;
}
final long length = _resource.getSize();
if (length < 0) {
// METAMODEL-30: Sometimes the size of the resource is not known
return null;
}
return _resource.read(inputStream -> {
try {
// read up to 5 megs of the file and approximate number of
// lines based on that.
final int sampleSize = (int) Math.min(length, 1024 * 1024 * 5);
final int chunkSize = Math.min(sampleSize, 1024 * 1024);
int readSize = 0;
int newlines = 0;
int carriageReturns = 0;
byte[] byteBuffer = new byte[chunkSize];
char[] charBuffer = new char[chunkSize];
while (readSize < sampleSize) {
final int read = inputStream.read(byteBuffer);
if (read == -1) {
break;
} else {
readSize += read;
}
Reader reader = getReader(byteBuffer, _configuration.getEncoding());
reader.read(charBuffer);
for (char c : charBuffer) {
if ('\n' == c) {
newlines++;
} else if ('\r' == c) {
carriageReturns++;
}
}
}
int lines = Math.max(newlines, carriageReturns);
logger.info("Found {} lines breaks in {} bytes", lines, sampleSize);
long approxCount = (long) (lines * length / sampleSize);
return approxCount;
} catch (IOException e) {
logger.error("Unexpected error during COUNT(*) approximation", e);
throw new IllegalStateException(e);
}
});
}
private Reader getReader(byte[] byteBuffer, String encoding) throws UnsupportedEncodingException {
try {
return new InputStreamReader(new ByteArrayInputStream(byteBuffer), encoding);
} catch (UnsupportedEncodingException e1) {
// this may happen on more exotic encodings, but since this reader
// is only meant for finding newlines, we'll try again with UTF8
try {
return new InputStreamReader(new ByteArrayInputStream(byteBuffer), "UTF8");
} catch (UnsupportedEncodingException e2) {
throw e1;
}
}
}
@Override
public DataSet materializeMainSchemaTable(Table table, List columns, int maxRows) {
final int lineNumber = _configuration.getColumnNameLineNumber();
final int columnCount = table.getColumnCount();
final BufferedReader reader = FileHelper.getBufferedReader(_resource.read(), _configuration.getEncoding());
try {
// skip column header lines
for (int i = 0; i < lineNumber; i++) {
String line = reader.readLine();
if (line == null) {
FileHelper.safeClose(reader);
return EmptyDataSet.fromColumns(columns);
}
}
} catch (IOException e) {
FileHelper.safeClose(reader);
throw new MetaModelException("IOException occurred while reading from CSV resource: " + _resource, e);
}
final boolean failOnInconsistentRowLength = _configuration.isFailOnInconsistentRowLength();
final Integer maxRowsOrNull = (maxRows > 0 ? maxRows : null);
if (_configuration.isMultilineValues()) {
final CSVReader csvReader = createCsvReader(reader);
return new CsvDataSet(csvReader, columns, maxRowsOrNull, columnCount, failOnInconsistentRowLength);
}
return new SingleLineCsvDataSet(reader, createParser(), columns, maxRowsOrNull, columnCount,
failOnInconsistentRowLength);
}
private ICSVParser createParser() {
final ICSVParser parser;
if (_configuration.getEscapeChar() == _configuration.getQuoteChar()) {
parser = new RFC4180ParserBuilder().withSeparator(_configuration.getSeparatorChar())
.withQuoteChar(_configuration.getQuoteChar()).build();
} else {
parser = new CSVParserBuilder().withSeparator(_configuration.getSeparatorChar())
.withQuoteChar(_configuration.getQuoteChar()).withEscapeChar(_configuration.getEscapeChar())
.build();
}
return parser;
}
protected CSVReader createCsvReader(int skipLines) {
final Reader reader = FileHelper.getReader(_resource.read(), _configuration.getEncoding());
return new CSVReader(reader, skipLines, createParser());
}
protected CSVReader createCsvReader(BufferedReader reader) {
return new CSVReader(reader, CSVReader.DEFAULT_SKIP_LINES, createParser());
}
@Override
protected CsvSchema getMainSchema() throws MetaModelException {
CsvSchema schema = new CsvSchema(getMainSchemaName(), this);
if (_resource.isExists()) {
schema.setTable(new CsvTable(schema, _resource.getName()));
}
return schema;
}
@Override
protected String getMainSchemaName() {
return ResourceUtils.getParentName(_resource);
}
protected boolean isWritable() {
return _writable;
}
private void checkWritable() {
if (!isWritable()) {
throw new IllegalStateException(
"This CSV DataContext is not writable, as it based on a read-only resource.");
}
}
@Override
public UpdateSummary executeUpdate(UpdateScript update) {
checkWritable();
final CsvUpdateCallback callback = new CsvUpdateCallback(this);
synchronized (WRITE_LOCK) {
try {
update.run(callback);
} finally {
callback.close();
}
}
return callback.getUpdateSummary();
}
}
