com.datastax.oss.driver.api.core.cql.PagingState Maven / Gradle / Ivy
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* 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,
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* See the License for the specific language governing permissions and
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*/
package com.datastax.oss.driver.api.core.cql;
import com.datastax.oss.driver.api.core.session.Session;
import com.datastax.oss.driver.internal.core.cql.DefaultPagingState;
import edu.umd.cs.findbugs.annotations.NonNull;
import edu.umd.cs.findbugs.annotations.Nullable;
import java.nio.ByteBuffer;
/**
* A safe wrapper around the paging state of a query.
*
* This class performs additional checks to fail fast if the paging state is not reused on the
* same query, and it provides utility methods for conversion to/from strings and byte arrays.
*
*
The serialized form returned by {@link #toBytes()} and {@link Object#toString()} is an opaque
* sequence of bytes. Note however that it is not cryptographically secure: the contents are
* not encrypted and the checks are performed with a simple MD5 checksum. If you need stronger
* guarantees, you should build your own wrapper around {@link ExecutionInfo#getPagingState()}.
*/
public interface PagingState {
/** Parses an instance from a string previously generated with {@code toString()}. */
@NonNull
static PagingState fromString(@NonNull String string) {
return DefaultPagingState.fromString(string);
}
/** Parses an instance from a byte array previously generated with {@link #toBytes()}. */
@NonNull
static PagingState fromBytes(byte[] bytes) {
return DefaultPagingState.fromBytes(bytes);
}
/** Returns a representation of this object as a byte array. */
byte[] toBytes();
/**
* Checks if this paging state can be safely reused for the given statement. Specifically, the
* query string and any bound values must match.
*
*
Note that, if {@code statement} is a {@link SimpleStatement} with bound values, those values
* must be encoded in order to perform the check. This method uses the default codec registry and
* default protocol version. This might fail if you use custom codecs; in that case, use {@link
* #matches(Statement, Session)} instead.
*
*
If {@code statement} is a {@link BoundStatement}, it is always safe to call this method.
*/
default boolean matches(@NonNull Statement statement) {
return matches(statement, null);
}
/**
* Alternative to {@link #matches(Statement)} that specifies the session the statement will be
* executed with. You only need this for simple statements, and if you use custom codecs.
* Bound statements already know which session they are attached to.
*/
boolean matches(@NonNull Statement statement, @Nullable Session session);
/**
* Returns the underlying "unsafe" paging state (the equivalent of {@link
* ExecutionInfo#getPagingState()}).
*/
@NonNull
ByteBuffer getRawPagingState();
}