com.google.gerrit.index.SchemaFieldDefs Maven / Gradle / Ivy
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// Licensed under the Apache License, Version 2.0 (the "License");
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// http://www.apache.org/licenses/LICENSE-2.0
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package com.google.gerrit.index;
import com.google.gerrit.common.Nullable;
import java.io.IOException;
/** Interfaces that define properties of fields in {@link Schema}. */
public class SchemaFieldDefs {
/**
* Definition of a field stored in the secondary index.
*
* {@link SchemaField}-s must not be changed once introduced to the codebase. Instead, a new
* FieldDef must be added and the old one removed from the schema (in two upgrade steps, see
* {@code com.google.gerrit.index.IndexUpgradeValidator}).
*
* @param input type from which documents are created and search results are returned.
* @param type that should be extracted from the input object when converting to an index
* document.
*/
public interface SchemaField {
/** Returns whether the field should be stored in the index. */
boolean isStored();
/** Returns whether the field is repeatable. */
boolean isRepeatable();
/**
* Get the field contents from the input object.
*
* @param input input object.
* @return the field value(s) to index.
*/
@Nullable
I get(T input);
/** Returns the name of the field. */
String getName();
/**
* Returns type of the field; for repeatable fields, the inner type, not the iterable type.
* TODO(mariasavtchuk): remove after migrating to the new field formats
*/
FieldType getType();
/**
* Set the field contents back to an object. Used to reconstruct fields from indexed values.
* No-op if the field can't be reconstructed.
*
* @param object input object.
* @param doc indexed document
* @return {@code true} if the field was set, {@code false} otherwise
*/
boolean setIfPossible(T object, StoredValue doc);
}
/**
* Getter to extract value that should be stored in index from the input object.
*
* This interface allows to specify a method or lambda for populating an index field. Note that
* for existing fields, changing the code of either the {@link Getter} implementation or the
* method(s) that it calls would invalidate existing index data. Therefore, instead of changing
* the semantics of an existing field, a new field must be added using the new semantics from the
* start. The old field can be removed in another upgrade step (cf. {@code
* com.google.gerrit.index.IndexUpgradeValidator}).
*
* @param type from which documents are created and search results are returned.
* @param type that should be extracted from the input object to an index field.
*/
@FunctionalInterface
public interface Getter {
@Nullable
T get(I input) throws IOException;
}
/**
* Setter to reconstruct fields from indexed values back to an object.
*
* See {@link Getter} for restrictions on changing the implementation.
*
* @param type from which documents are created and search results are returned.
* @param type that should be extracted from the input object when converting toto an index
* field.
*/
@FunctionalInterface
public interface Setter {
void set(I object, T value);
}
}