| /** |
| * 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.trevni; |
| |
| import java.io.IOException; |
| import java.io.Closeable; |
| import java.io.File; |
| import java.util.Arrays; |
| import java.util.Map; |
| import java.util.List; |
| import java.util.ArrayList; |
| import java.util.HashMap; |
| |
| /** Reads data from a column file. */ |
| public class ColumnFileReader implements Closeable { |
| private Input file; |
| |
| private long rowCount; |
| private int columnCount; |
| private ColumnFileMetaData metaData; |
| private ColumnDescriptor[] columns; |
| private Map<String,ColumnDescriptor> columnsByName; |
| |
| /** Construct reading from the named file. */ |
| public ColumnFileReader(File file) throws IOException { |
| this(new InputFile(file)); |
| } |
| |
| /** Construct reading from the provided input. */ |
| public ColumnFileReader(Input file) throws IOException { |
| this.file = file; |
| readHeader(); |
| } |
| |
| /** Return the number of rows in this file. */ |
| public long getRowCount() { return rowCount; } |
| |
| /** Return the number of columns in this file. */ |
| public long getColumnCount() { return columnCount; } |
| |
| /** Return this file's metadata. */ |
| public ColumnFileMetaData getMetaData() { return metaData; } |
| |
| /** Return all columns' metadata. */ |
| public ColumnMetaData[] getColumnMetaData() { |
| ColumnMetaData[] result = new ColumnMetaData[columnCount]; |
| for (int i = 0; i < columnCount; i++) |
| result[i] = columns[i].metaData; |
| return result; |
| } |
| |
| /** Return root columns' metadata. Roots are columns that have no parent. */ |
| public List<ColumnMetaData> getRoots() { |
| List<ColumnMetaData> result = new ArrayList<ColumnMetaData>(); |
| for (int i = 0; i < columnCount; i++) |
| if (columns[i].metaData.getParent() == null) |
| result.add(columns[i].metaData); |
| return result; |
| } |
| |
| /** Return a column's metadata. */ |
| public ColumnMetaData getColumnMetaData(int number) { |
| return columns[number].metaData; |
| } |
| |
| /** Return a column's metadata. */ |
| public ColumnMetaData getColumnMetaData(String name) { |
| return getColumn(name).metaData; |
| } |
| |
| private <T extends Comparable> ColumnDescriptor<T> getColumn(String name) { |
| ColumnDescriptor column = columnsByName.get(name); |
| if (column == null) |
| throw new TrevniRuntimeException("No column named: "+name); |
| return (ColumnDescriptor<T>)column; |
| } |
| |
| private void readHeader() throws IOException { |
| InputBuffer in = new InputBuffer(file, 0); |
| readMagic(in); |
| this.rowCount = in.readFixed64(); |
| this.columnCount = in.readFixed32(); |
| this.metaData = ColumnFileMetaData.read(in); |
| this.columnsByName = new HashMap<String,ColumnDescriptor>(columnCount); |
| |
| columns = new ColumnDescriptor[columnCount]; |
| readColumnMetaData(in); |
| readColumnStarts(in); |
| } |
| |
| private void readMagic(InputBuffer in) throws IOException { |
| byte[] magic = new byte[ColumnFileWriter.MAGIC.length]; |
| try { |
| in.readFully(magic); |
| } catch (IOException e) { |
| throw new IOException("Not a data file."); |
| } |
| if (!(Arrays.equals(ColumnFileWriter.MAGIC, magic) |
| || !Arrays.equals(ColumnFileWriter.MAGIC_1, magic) |
| || !Arrays.equals(ColumnFileWriter.MAGIC_0, magic))) |
| throw new IOException("Not a data file."); |
| } |
| |
| private void readColumnMetaData(InputBuffer in) throws IOException { |
| for (int i = 0; i < columnCount; i++) { |
| ColumnMetaData meta = ColumnMetaData.read(in, this); |
| meta.setDefaults(this.metaData); |
| ColumnDescriptor column = new ColumnDescriptor(file, meta); |
| columns[i] = column; |
| meta.setNumber(i); |
| columnsByName.put(meta.getName(), column); |
| } |
| } |
| |
| private void readColumnStarts(InputBuffer in) throws IOException { |
| for (int i = 0; i < columnCount; i++) |
| columns[i].start = in.readFixed64(); |
| } |
| |
| /** Return an iterator over values in the named column. */ |
| public <T extends Comparable> ColumnValues<T> getValues(String columnName) |
| throws IOException { |
| return new ColumnValues<T>(getColumn(columnName)); |
| } |
| |
| /** Return an iterator over values in a column. */ |
| public <T extends Comparable> ColumnValues<T> getValues(int column) |
| throws IOException { |
| return new ColumnValues<T>(columns[column]); |
| } |
| |
| @Override public void close() throws IOException { |
| file.close(); |
| } |
| |
| } |
| |