Java tutorial
/* * 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.phoenix.schema; import java.util.List; import org.apache.hadoop.hbase.io.ImmutableBytesWritable; import org.apache.hadoop.io.WritableUtils; import org.apache.http.annotation.Immutable; import org.apache.phoenix.exception.SQLExceptionCode; import org.apache.phoenix.exception.SQLExceptionInfo; import org.apache.phoenix.expression.Expression; import org.apache.phoenix.schema.tuple.Tuple; import org.apache.phoenix.schema.types.PDataType; import org.apache.phoenix.util.ByteUtil; /** * * Simple flat schema over a byte array where fields may be any of {@link org.apache.phoenix.schema.types.PDataType}. * Optimized for positional access by index. * * * @since 0.1 */ @Immutable public class KeyValueSchema extends ValueSchema { public KeyValueSchema() { } protected KeyValueSchema(int minNullable, List<Field> fields) { super(minNullable, fields); } public static class KeyValueSchemaBuilder extends ValueSchemaBuilder { public KeyValueSchemaBuilder(int minNullable) { super(minNullable); } @Override public KeyValueSchema build() { List<Field> condensedFields = buildFields(); return new KeyValueSchema(this.minNullable, condensedFields); } @Override public KeyValueSchemaBuilder setMaxFields(int nFields) { super.setMaxFields(nFields); return this; } public KeyValueSchemaBuilder addField(PDatum datum) { super.addField(datum, fields.size() >= this.minNullable, SortOrder.getDefault()); return this; } } public boolean isNull(int position, ValueBitSet bitSet) { int nBit = position - getMinNullable(); return (nBit >= 0 && !bitSet.get(nBit)); } private static byte[] ensureSize(byte[] b, int offset, int size) { if (size > b.length) { byte[] bBigger = new byte[Math.max(b.length * 2, size)]; System.arraycopy(b, 0, bBigger, 0, b.length); return bBigger; } return b; } /** * @return byte representation of the KeyValueSchema */ public byte[] toBytes(Expression[] expressions, ValueBitSet valueSet, ImmutableBytesWritable ptr) { return toBytes(null, expressions, valueSet, ptr); } /** * @return byte representation of the KeyValueSchema */ public byte[] toBytes(Tuple tuple, Expression[] expressions, ValueBitSet valueSet, ImmutableBytesWritable ptr) { int offset = 0; int index = 0; valueSet.clear(); int minNullableIndex = getMinNullable(); byte[] b = new byte[getEstimatedValueLength() + valueSet.getEstimatedLength()]; List<Field> fields = getFields(); // We can get away with checking if only nulls are left in the outer loop, // since repeating fields will not span the non-null/null boundary. for (int i = 0; i < fields.size(); i++) { Field field = fields.get(i); PDataType type = field.getDataType(); for (int j = 0; j < field.getCount(); j++) { if (expressions[index].evaluate(tuple, ptr) && ptr.getLength() > 0) { // Skip null values if (index >= minNullableIndex) { valueSet.set(index - minNullableIndex); } if (!type.isFixedWidth()) { b = ensureSize(b, offset, offset + getVarLengthBytes(ptr.getLength())); offset = writeVarLengthField(ptr, b, offset); } else { int nBytes = ptr.getLength(); b = ensureSize(b, offset, offset + nBytes); System.arraycopy(ptr.get(), ptr.getOffset(), b, offset, nBytes); offset += nBytes; } } index++; } } // Add information about which values were set at end of value, // so that we can quickly access them without needing to walk // through the values using the schema. // TODO: if there aren't any non null values, don't serialize anything b = ensureSize(b, offset, offset + valueSet.getEstimatedLength()); offset = valueSet.toBytes(b, offset); if (offset == b.length) { return b; } else { byte[] bExact = new byte[offset]; System.arraycopy(b, 0, bExact, 0, offset); return bExact; } } private int getVarLengthBytes(int length) { return length + WritableUtils.getVIntSize(length); } private int writeVarLengthField(ImmutableBytesWritable ptr, byte[] b, int offset) { int length = ptr.getLength(); offset += ByteUtil.vintToBytes(b, offset, length); System.arraycopy(ptr.get(), ptr.getOffset(), b, offset, length); offset += length; return offset; } @edu.umd.cs.findbugs.annotations.SuppressWarnings(value = "NP_BOOLEAN_RETURN_NULL", justification = "Designed to return null.") public Boolean iterator(byte[] src, int srcOffset, int srcLength, ImmutableBytesWritable ptr, int position, ValueBitSet valueBitSet) { ptr.set(src, srcOffset, 0); int maxOffset = srcOffset + srcLength; Boolean hasValue = null; for (int i = 0; i < position; i++) { hasValue = next(ptr, i, maxOffset, valueBitSet); } return hasValue; } public Boolean iterator(ImmutableBytesWritable srcPtr, ImmutableBytesWritable ptr, int position, ValueBitSet valueSet) { return iterator(srcPtr.get(), srcPtr.getOffset(), srcPtr.getLength(), ptr, position, valueSet); } public Boolean iterator(ImmutableBytesWritable ptr, int position, ValueBitSet valueSet) { return iterator(ptr, ptr, position, valueSet); } public Boolean iterator(ImmutableBytesWritable ptr) { return iterator(ptr, ptr, 0, ValueBitSet.EMPTY_VALUE_BITSET); } /** * Move the bytes ptr to the next position relative to the current ptr * @param ptr bytes pointer pointing to the value at the positional index * provided. * @param position zero-based index of the next field in the value schema * @param maxOffset max possible offset value when iterating * @return true if a value was found and ptr was set, false if the value is null and ptr was not * set, and null if the value is null and there are no more values */ @edu.umd.cs.findbugs.annotations.SuppressWarnings(value = "NP_BOOLEAN_RETURN_NULL", justification = "Designed to return null.") public Boolean next(ImmutableBytesWritable ptr, int position, int maxOffset, ValueBitSet valueSet) { if (ptr.getOffset() + ptr.getLength() >= maxOffset) { ptr.set(ptr.get(), maxOffset, 0); return null; } if (position >= getFieldCount()) { return null; } // Move the pointer past the current value and set length // to 0 to ensure you never set the ptr past the end of the // backing byte array. ptr.set(ptr.get(), ptr.getOffset() + ptr.getLength(), 0); if (!isNull(position, valueSet)) { Field field = this.getField(position); int length = field.getDataType().isFixedWidth() ? field.getByteSize() : ByteUtil.vintFromBytes(ptr); if (ptr.getOffset() + length > maxOffset) { throw new RuntimeException(new SQLExceptionInfo.Builder(SQLExceptionCode.ILLEGAL_DATA) .setMessage("Expected length of at least " + length + " bytes, but had " + (maxOffset - ptr.getOffset())) .build().buildException()); } ptr.set(ptr.get(), ptr.getOffset(), length); return ptr.getLength() > 0; } return false; } }