com.hazelcast.internal.serialization.impl.PortablePositionNavigator Maven / Gradle / Ivy
/*
* Copyright (c) 2008-2016, Hazelcast, Inc. All Rights Reserved.
*
* Licensed 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 com.hazelcast.internal.serialization.impl;
import com.hazelcast.nio.Bits;
import com.hazelcast.nio.BufferObjectDataInput;
import com.hazelcast.nio.serialization.FieldType;
import java.io.IOException;
import java.util.LinkedList;
import java.util.List;
import static com.hazelcast.internal.serialization.impl.PortableNavigatorContext.NavigationFrame;
import static com.hazelcast.internal.serialization.impl.PortablePositionFactory.emptyAnyPosition;
import static com.hazelcast.internal.serialization.impl.PortablePositionFactory.nilAnyPosition;
import static com.hazelcast.internal.serialization.impl.PortablePositionFactory.nilNotLeafPosition;
import static com.hazelcast.internal.serialization.impl.PortableUtils.createUnknownFieldException;
import static com.hazelcast.internal.serialization.impl.PortableUtils.createWrongUseOfAnyOperationException;
import static com.hazelcast.internal.serialization.impl.PortableUtils.isCurrentPathTokenWithAnyQuantifier;
import static com.hazelcast.internal.serialization.impl.PortableUtils.isCurrentPathTokenWithoutQuantifier;
import static com.hazelcast.internal.serialization.impl.PortableUtils.validateAndGetArrayQuantifierFromCurrentToken;
import static com.hazelcast.internal.serialization.impl.PortableUtils.validateArrayType;
import static com.hazelcast.internal.serialization.impl.PortableUtils.validateFactoryAndClass;
/**
* Enables navigation in the portable byte stream.
* The contract is very simple: you give a path to an element, like "person.body.iq" and it returns a
* {@link PortablePosition} that includes the type of the found element and its location in the stream.
*
* The navigator is not stateful - everything is static.
*/
final class PortablePositionNavigator {
private static final boolean SINGLE_CELL_ACCESS = true;
private static final boolean WHOLE_ARRAY_ACCESS = false;
private PortablePositionNavigator() {
}
/**
* Main method that enables navigating in the Portable byte stream to find the element specified in the path.
* The path may be:
* - simple -> which means that it includes a single attribute only, like "name"
* - nested -> which means that it includes more then a single attribute separated with a dot (.). like person.name
*
* The path may also includes array cells:
* - specific quantifier, like person.leg[1] -> returns the leg with index 0
* - wildcard quantifier, like person.leg[any] -> returns all legs
*
* The wildcard quantifier may be used a couple of times, like person.leg[any].finger[any] which returns all fingers
* from all legs.
*
* Returns a {@link PortablePosition} that includes the type of the found element and its location in the stream.
* E.g. car.wheels[0].pressure -> the position will point to the pressure object
*
* @param ctx context of the navigation that encompasses inputStream, classDefinition and all other required fields
* @param path pathCursor that's required to navigate down the path to the leaf token
* @return PortablePosition of the found element. It may be a PortableSinglePosition or a PortableMultiPosition
* @throws IOException in case of any stream reading errors
*/
static PortablePosition findPositionForReading(
PortableNavigatorContext ctx, String pathString, PortablePathCursor path) throws IOException {
// just a a single attribute path - e.g. reading a field
PortablePosition result = findPositionForReadingAssumingSingleAttributePath(ctx, pathString, path);
if (result != null) {
return result;
}
// nested path or path with array quantifier
return findPositionForReadingComplexPath(ctx, pathString, path);
}
private static PortablePosition findPositionForReadingAssumingSingleAttributePath(
PortableNavigatorContext ctx, String pathString, PortablePathCursor path) throws IOException {
path.initWithSingleTokenPath(pathString);
// fast track for paths that have a single token only
if (ctx.trySetupContextForSingleTokenPath(path.path())) {
PortablePosition result = createPositionForReadAccess(ctx, path, -1);
if (result != null) {
return result;
}
}
return null;
}
private static PortablePosition findPositionForReadingComplexPath(
PortableNavigatorContext ctx, String pathString, PortablePathCursor path) throws IOException {
path.init(pathString);
PortablePosition result = navigateThroughAllTokensAndReturnPositionForReading(ctx, path, null);
if (ctx.areThereMultiPositions()) {
// If [any] operator is used the path may contains multi-positions.
// A read with [any] operator may result in returning multiple values, so know we have to iterate over all
// positions where the path has diverged to get the additional positions where the reader should read the
// values.
return processPendingMultiPositionsAndReturnMultiResult(ctx, path, result);
} else {
// In this case, there are no multi-position so we can just return the single result.
return returnSingleResultWhenNoMultiPositions(path, result);
}
}
private static PortablePosition navigateThroughAllTokensAndReturnPositionForReading(
PortableNavigatorContext ctx, PortablePathCursor path, NavigationFrame frame) throws IOException {
// Iterates over path tokens and processes them, ex. car.wheel[0].pressure
// The navigateToPathToken invocation of a non-last token moves the cursor forward.
// If null or empty position reached on the way it is returned to finish the iteration earlier, since there's no
// non-null element to continue the iteration from.
// The navigateToPathToken invocation of the last token returns the position where the reader should read the
// attribute's value.
PortablePosition result;
do {
result = navigateToPathToken(ctx, path, frame);
if (result != null && result.isNullOrEmpty()) {
break;
}
frame = null;
} while (path.advanceToNextToken());
// All path tokens have been read but no result hast been returned. It means that the element is unknown.
// Otherwise some non-null, null or empty result would have been returned.
if (result == null) {
throw createUnknownFieldException(ctx, path.path());
}
return result;
}
private static PortablePosition navigateToPathToken(
PortableNavigatorContext ctx, PortablePathCursor path, NavigationFrame frame) throws IOException {
// first, setup the context for the current path token
ctx.setupContextForGivenPathToken(path);
if (isCurrentPathTokenWithoutQuantifier(path.token())) {
// ex: attribute
PortablePosition result = navigateToPathTokenWithoutQuantifier(ctx, path);
if (result != null) {
return result;
}
} else if (isCurrentPathTokenWithAnyQuantifier(path.token())) {
// ex: attribute[any]
PortablePosition result = navigateToPathTokenWithAnyQuantifier(ctx, path, frame);
if (result != null) {
return result;
}
} else {
// ex: attribute[2]
PortablePosition result = navigateToPathTokenWithNumberQuantifier(ctx, path);
if (result != null) {
return result;
}
}
return null;
}
/**
* Token without quantifier. It means it's just a simple field, not an array.
*/
private static PortablePosition navigateToPathTokenWithoutQuantifier(
PortableNavigatorContext ctx, PortablePathCursor path) throws IOException {
if (path.isLastToken()) {
// if it's a token that's on the last position we calculate its direct access position and return it for
// reading in the value reader.
return createPositionForReadAccess(ctx, path);
} else {
// if it's not a token that's on the last position in the path we advance the position to the next token
// we also adjust the context, since advancing means that we are in the context of other
// (and possibly different) portable type.
if (!navigateContextToNextPortableTokenFromPortableField(ctx)) {
// we return null if we didn't manage to advance from the current token to the next one.
// For example: it may happen if the current token points to a null object.
return nilNotLeafPosition();
}
}
return null;
}
private static PortablePosition returnSingleResultWhenNoMultiPositions(
PortablePathCursor path, PortablePosition result) {
// if the position is null or empty we don't need to do any processing, we just return it as-is.
if (!result.isNullOrEmpty()) {
// for consistency: [any] queries always return a multi-result, even if there's a single result only.
// The only case where it returns a PortableSingleResult is when the position is a a single null result.
// otherwise we always allocate a MultiResult to indicate to the reader that it's a multi-position.
if (path.isAnyPath()) {
return PortablePositionFactory.createMultiPosition(result);
}
}
return result;
}
private static PortablePosition processPendingMultiPositionsAndReturnMultiResult(
PortableNavigatorContext ctx, PortablePathCursor path, PortablePosition result) throws IOException {
// we process the all the paths gathered due to [any] quantifiers
List positions = new LinkedList();
// first add the single position to the result gathered in single path navigation
positions.add(result);
// then process all multi-positions and gather the results
while (ctx.areThereMultiPositions()) {
// setup navigation context and path for the given navigation frame
NavigationFrame frame = ctx.pollFirstMultiPosition();
setupContextAndPathWithFrameState(ctx, path, frame);
// navigate to the last token and gather the result
result = navigateThroughAllTokensAndReturnPositionForReading(ctx, path, frame);
positions.add(result);
}
return PortablePositionFactory.createMultiPosition(positions);
}
private static void setupContextAndPathWithFrameState(
PortableNavigatorContext ctx, PortablePathCursor path, NavigationFrame frame) {
ctx.advanceContextToGivenFrame(frame);
path.index(frame.pathTokenIndex);
}
// token with [any] quantifier
private static PortablePosition navigateToPathTokenWithAnyQuantifier(
PortableNavigatorContext ctx, PortablePathCursor path, NavigationFrame frame) throws IOException {
// check if the underlying field is of array type
validateArrayType(ctx.getCurrentClassDefinition(), ctx.getCurrentFieldDefinition(), path.path());
if (ctx.isCurrentFieldOfType(FieldType.PORTABLE_ARRAY)) {
// the result will be returned if it was the last token of the path, otherwise it has just moved further.
PortablePosition result = navigateToPathTokenWithAnyQuantifierInPortableArray(ctx, path, frame);
if (result != null) {
return result;
}
} else {
// there will always be a result since it's impossible to navigate further from a primitive field.
return navigateToPathTokenWithAnyQuantifierInPrimitiveArray(ctx, path, frame);
}
return null;
}
// navigation in PORTABLE array
private static PortablePosition navigateToPathTokenWithAnyQuantifierInPortableArray(
PortableNavigatorContext ctx, PortablePathCursor path, NavigationFrame frame) throws IOException {
// if no frame, we're pursuing the cell[0] case and populating the frames for cell[1 to length-1]
if (frame == null) {
// first we check if array null or empty
int len = getArrayLengthOfTheField(ctx);
PortablePosition result = doValidateArrayLengthForAnyQuantifier(len, path.isLastToken());
if (result != null) {
return result;
}
// then we populate frames for cell[1 to length-1]
ctx.populateAnyNavigationFrames(path.index(), len);
// pursue navigation to index 0, return result if last token
int cellIndex = 0;
result = doNavigateToPortableArrayCell(ctx, path, cellIndex);
if (result != null) {
return result;
}
} else {
// pursue navigation to index given by the frame, return result if last token
// no validation since it index in-bound has been validated while the navigation frames have been populated
PortablePosition result = doNavigateToPortableArrayCell(ctx, path, frame.arrayIndex);
if (result != null) {
return result;
}
}
return null;
}
private static PortablePosition doValidateArrayLengthForAnyQuantifier(int len, boolean lastToken) {
if (len == 0) {
return emptyAnyPosition(lastToken);
} else if (len == Bits.NULL_ARRAY_LENGTH) {
return nilAnyPosition(lastToken);
}
return null;
}
private static PortablePosition doNavigateToPortableArrayCell(
PortableNavigatorContext ctx, PortablePathCursor path, int index) throws IOException {
if (path.isLastToken()) {
// if last token of the path we return the position for reading
return createPositionForReadAccess(ctx, path, index);
} else {
// otherwise we navigate further down the path
navigateContextToNextPortableTokenFromPortableArrayCell(ctx, path, index);
}
return null;
}
// navigation in PRIMITIVE array
private static PortablePosition navigateToPathTokenWithAnyQuantifierInPrimitiveArray(
PortableNavigatorContext ctx, PortablePathCursor path, NavigationFrame frame) throws IOException {
// if no frame, we're pursuing the cell[0] case and populating the frames for cell[1 to length-1]
if (frame == null) {
if (path.isLastToken()) {
// first we check if array null or empty
int len = getArrayLengthOfTheField(ctx);
PortablePosition result = doValidateArrayLengthForAnyQuantifier(len, path.isLastToken());
if (result != null) {
return result;
}
// then we populate frames for cell[1 to length-1]
ctx.populateAnyNavigationFrames(path.index(), len);
// finally, we return the cell's position for reading -> cell[0]
return createPositionForReadAccess(ctx, path, 0);
}
// primitive array cell has to be a last token, there's no furhter navigation from there.
throw createWrongUseOfAnyOperationException(ctx, path.path());
} else {
if (path.isLastToken()) {
return createPositionForReadAccess(ctx, path, frame.arrayIndex);
}
throw createWrongUseOfAnyOperationException(ctx, path.path());
}
}
/**
* Token with [number] quantifier. It means we are navigating in an array cell.
*/
private static PortablePosition navigateToPathTokenWithNumberQuantifier(
PortableNavigatorContext ctx, PortablePathCursor path) throws IOException {
// makes sure that the field type is an array and parses the qantifier
validateArrayType(ctx.getCurrentClassDefinition(), ctx.getCurrentFieldDefinition(), path.path());
int index = validateAndGetArrayQuantifierFromCurrentToken(path.token(), path.path());
// reads the array length and checks if the index is in-bound
int len = getArrayLengthOfTheField(ctx);
if (len == 0) {
return emptyAnyPosition(path.isLastToken());
} else if (len == Bits.NULL_ARRAY_LENGTH) {
return nilAnyPosition(path.isLastToken());
} else if (index >= len) {
return nilAnyPosition(path.isLastToken());
} else {
// when index in-bound
if (path.isLastToken()) {
// if it's a token that's on the last position we calculate its direct access position and return it for
// reading in the value reader.
return createPositionForReadAccess(ctx, path, index);
} else if (ctx.isCurrentFieldOfType(FieldType.PORTABLE_ARRAY)) {
// otherwise we advance only if the type is a portable_array. We cannot navigate further in a primitive
// type and the portable arrays may store portable or primitive types only.
navigateContextToNextPortableTokenFromPortableArrayCell(ctx, path, index);
}
}
return null;
}
// returns true if managed to advance, false if advance failed due to null field
private static boolean navigateContextToNextPortableTokenFromPortableField(PortableNavigatorContext ctx)
throws IOException {
BufferObjectDataInput in = ctx.getIn();
// find the field position that's stored in the fieldDefinition int the context and navigate to it
int pos = getStreamPositionOfTheField(ctx);
in.position(pos);
// check if it's null, if so return false indicating that the navigation has failed
boolean isNull = in.readBoolean();
if (isNull) {
return false;
}
// read factory and class Id and validate if it's the same as expected in the fieldDefinition
int factoryId = in.readInt();
int classId = in.readInt();
int versionId = in.readInt();
// initialise context with the given portable field for further navigation
ctx.advanceContextToNextPortableToken(factoryId, classId, versionId);
return true;
}
// this navigation always succeeds since the caller validates if the index is inbound
private static void navigateContextToNextPortableTokenFromPortableArrayCell(
PortableNavigatorContext ctx, PortablePathCursor path, int index) throws IOException {
BufferObjectDataInput in = ctx.getIn();
// find the array field position that's stored in the fieldDefinition int the context and navigate to it
int pos = getStreamPositionOfTheField(ctx);
in.position(pos);
// read array length and ignore
in.readInt();
// read factory and class Id and validate if it's the same as expected in the fieldDefinition
int factoryId = in.readInt();
int classId = in.readInt();
validateFactoryAndClass(ctx.getCurrentFieldDefinition(), factoryId, classId, path.path());
// calculate the offset of the cell given by the index
final int cellOffset = in.position() + index * Bits.INT_SIZE_IN_BYTES;
in.position(cellOffset);
// read the position of the portable addressed in this array cell (array contains portable position only)
int portablePosition = in.readInt();
// navigate to portable position and read it's version
in.position(portablePosition);
int versionId = in.readInt();
// initialise context with the given portable field for further navigation
ctx.advanceContextToNextPortableToken(factoryId, classId, versionId);
}
/**
* Create an instance of the {@PortablePosition} for direct reading in the reader class.
* The cursor and the path point to the leaf field, but there's still some adjustments to be made in certain cases.
*
* - If it's a primitive array cell that is being accessed with the [number] quantifier the stream has to be
* adjusted to point to the cell specified by the index.
*
* - If it's a portable attribute that is being accessed the factoryId and classId have to be read and validated.
* They are required for the portable read operation.
*
* - If it's a portable array cell that is being accessed with the [number] quantifier the stream has to be
* adjusted to point to the cell specified by the index. Also the factoryId and classId have to be read and
* validated. They are required for the portable read operation.
*
* If it's a whole portable array that is being accessed factoryId and classId have to be read and
* validated. The length have to be read.
*
* If it's a whole primitive array or a primitive field that is being accessed there's nothing to be adjusted.
*/
private static PortablePosition createPositionForReadAccess(
PortableNavigatorContext ctx, PortablePathCursor path, int index) throws IOException {
FieldType type = ctx.getCurrentFieldType();
if (type.isArrayType()) {
if (type == FieldType.PORTABLE_ARRAY) {
return createPositionForReadAccessInPortableArray(ctx, path, index);
} else {
return createPositionForReadAccessInPrimitiveArray(ctx, path, index);
}
} else {
validateNonArrayPosition(path, index);
return createPositionForReadAccessInFromAttribute(ctx, path, index, type);
}
}
private static PortablePosition createPositionForReadAccessInPortableArray(
PortableNavigatorContext ctx, PortablePathCursor path, int index) throws IOException {
if (index >= 0) {
// accessing a single cell of a portable array
return createPositionForPortableArrayAccess(ctx, path, index, SINGLE_CELL_ACCESS);
} else {
// accessing a whole portable array
return createPositionForPortableArrayAccess(ctx, path, index, WHOLE_ARRAY_ACCESS);
}
}
private static PortablePosition createPositionForReadAccessInPrimitiveArray(
PortableNavigatorContext ctx, PortablePathCursor path, int index) throws IOException {
if (index >= 0) {
// accessing single cell of a primitive array
return createPositionForSingleCellPrimitiveArrayAccess(ctx, path, index);
}
// accessing a whole primitive array
// we don't need to adjust anything otherwise - a primitive array can be read without any adjustments
return createPositionForPrimitiveFieldAccess(ctx, path, index);
}
private static PortablePosition createPositionForReadAccessInFromAttribute(
PortableNavigatorContext ctx, PortablePathCursor path, int index, FieldType type) throws IOException {
if (type != FieldType.PORTABLE) {
// accessing a primitive field
// we don't need to adjust anything otherwise - a primitive field can be read without any adjustments
return createPositionForPrimitiveFieldAccess(ctx, path, index);
}
// accessing a portable field
return createPositionForPortableFieldAccess(ctx, path);
}
/**
* Special case of the position creation, where there's no quantifier, so the index does not count.
*/
private static PortablePosition createPositionForReadAccess(
PortableNavigatorContext ctx, PortablePathCursor path) throws IOException {
int notArrayCellAccessIndex = -1;
return createPositionForReadAccess(ctx, path, notArrayCellAccessIndex);
}
private static void validateNonArrayPosition(PortablePathCursor path, int index) {
if (index >= 0) {
throw new IllegalArgumentException(
"Non array position expected, but the cell index is " + index + " in path" + path.path());
}
}
private static PortablePosition createPositionForSingleCellPrimitiveArrayAccess(
PortableNavigatorContext ctx, PortablePathCursor path, int index) throws IOException {
// assumes position.getIndex() >= 0
BufferObjectDataInput in = ctx.getIn();
in.position(getStreamPositionOfTheField(ctx));
// read the array length and ignore it, it has been already validated
in.readInt();
int streamPosition;
if (ctx.getCurrentFieldType() == FieldType.UTF || ctx.getCurrentFieldType() == FieldType.UTF_ARRAY) {
// UTF arrays actually need iterating over all elements to read the length of each element
// it's impossible to dead-reckon about a cell's position
int currentIndex = 0;
while (index > currentIndex) {
int indexElementLen = in.readInt();
in.position(in.position() + indexElementLen);
currentIndex++;
}
streamPosition = in.position();
} else {
// in primitive non-utf arrays we can dead-reckon about a cell's position
streamPosition = in.position() + index * ctx.getCurrentFieldType().getSingleType().getTypeSize();
}
return PortablePositionFactory.createSinglePrimitivePosition(ctx.getCurrentFieldDefinition(), streamPosition,
index, path.isLastToken());
}
private static PortablePosition createPositionForPortableFieldAccess(
PortableNavigatorContext ctx, PortablePathCursor path) throws IOException {
BufferObjectDataInput in = ctx.getIn();
in.position(getStreamPositionOfTheField(ctx));
// read and validate portable properties
boolean nil = in.readBoolean();
int factoryId = in.readInt();
int classId = in.readInt();
int streamPosition = in.position();
validateFactoryAndClass(ctx.getCurrentFieldDefinition(), factoryId, classId, path.path());
return PortablePositionFactory.createSinglePortablePosition(ctx.getCurrentFieldDefinition(), streamPosition,
factoryId, classId, nil, path.isLastToken());
}
private static PortablePosition createPositionForPortableArrayAccess(
PortableNavigatorContext ctx, PortablePathCursor path, int index, boolean singleCellAccess)
throws IOException {
BufferObjectDataInput in = ctx.getIn();
in.position(getStreamPositionOfTheField(ctx));
// read and validate portable properties
int len = in.readInt();
int factoryId = in.readInt();
int classId = in.readInt();
int streamPosition = in.position();
validateFactoryAndClass(ctx.getCurrentFieldDefinition(), factoryId, classId, path.path());
// if single-cell access, dead-reckon cell's position that's specified by the index
if (singleCellAccess) {
if (index < len) {
int offset = in.position() + index * Bits.INT_SIZE_IN_BYTES;
in.position(offset);
streamPosition = in.readInt();
} else {
// return null if index out-of-bound
return PortablePositionFactory.nil(path.isLastToken());
}
}
return PortablePositionFactory.createSinglePortablePosition(ctx.getCurrentFieldDefinition(), streamPosition,
factoryId, classId, index, len, path.isLastToken());
}
private static PortablePosition createPositionForPrimitiveFieldAccess(
PortableNavigatorContext ctx, PortablePathCursor path, int index) throws IOException {
// for primitive field access there's no adjustment needed, so a position is populated from the current ctx
ctx.getIn().position(getStreamPositionOfTheField(ctx));
return PortablePositionFactory.createSinglePrimitivePosition(ctx.getCurrentFieldDefinition(),
ctx.getIn().position(), index, path.isLastToken());
}
// convenience
private static int getStreamPositionOfTheField(PortableNavigatorContext ctx) throws IOException {
return PortableUtils.getStreamPositionOfTheField(ctx.getCurrentFieldDefinition(), ctx.getIn(),
ctx.getCurrentOffset());
}
private static int getArrayLengthOfTheField(PortableNavigatorContext ctx) throws IOException {
return PortableUtils.getArrayLengthOfTheField(ctx.getCurrentFieldDefinition(), ctx.getIn(),
ctx.getCurrentOffset());
}
}