path: root/icing/schema/schema-util.h

// Copyright (C) 2019 Google LLC
//
// 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.

#ifndef ICING_SCHEMA_SCHEMA_UTIL_H_
#define ICING_SCHEMA_SCHEMA_UTIL_H_

#include <cstdint>
#include <string>
#include <string_view>
#include <unordered_map>
#include <unordered_set>

#include "icing/text_classifier/lib3/utils/base/status.h"
#include "icing/text_classifier/lib3/utils/base/statusor.h"
#include "icing/proto/schema.pb.h"

namespace icing {
namespace lib {

class SchemaUtil {
 public:
  using TypeConfigMap =
      std::unordered_map<std::string, const SchemaTypeConfigProto>;

  // A data structure that stores the relationships between schema types. The
  // keys in TypeRelationMap are schema types, and the values are sets of schema
  // types that are directly or indirectly related to the key.
  template <typename T>
  using TypeRelationMap =
      std::unordered_map<std::string_view,
                         std::unordered_map<std::string_view, T>>;

  // If A -> B is indicated in the map, then type A must be built before
  // building type B, which implies one of the following situations.
  //
  // 1. B has a property of type A.
  // 2. A is a parent type of B via polymorphism.
  //
  // For the first case, this map will also include all PropertyConfigProto
  // (with DOCUMENT data_type) pointers which *directly* connects type A and B.
  // IOW, this vector of PropertyConfigProto* are "direct edges" connecting A
  // and B directly. It will be an empty vector if A and B are not "directly"
  // connected, but instead via another intermediate level of schema type. For
  // example, the actual dependency is A -> C -> B, so there will be A -> C and
  // C -> B with valid PropertyConfigProto* respectively in this map, but we
  // will also expand transitive dependents: add A -> B into dependent map with
  // empty vector of "edges".
  using DependentMap = TypeRelationMap<std::vector<const PropertyConfigProto*>>;

  // If A -> B is indicated in the map, then type A is a parent type of B,
  // directly or indirectly. If directly, the bool value in the map will be
  // true, otherwise false.
  //
  // Note that all relationships contained in this map are also entries in the
  // DependentMap, i.e. if B inherits from A, then there will be a mapping from
  // A to B in both this map and the DependentMap.
  using InheritanceMap = TypeRelationMap<bool>;

  struct SchemaDelta {
    // Which schema types were present in the old schema, but were deleted from
    // the new schema.
    std::unordered_set<std::string> schema_types_deleted;

    // Which schema types had their SchemaTypeConfigProto changed in a way that
    // could invalidate existing Documents of that schema type.
    std::unordered_set<std::string> schema_types_incompatible;

    // Schema types that were added in the new schema. Represented by the
    // `schema_type` field in the SchemaTypeConfigProto.
    std::unordered_set<std::string> schema_types_new;

    // Schema types that were changed in a way that was backwards compatible and
    // didn't invalidate the index. Represented by the `schema_type` field in
    // the SchemaTypeConfigProto.
    std::unordered_set<std::string> schema_types_changed_fully_compatible;

    // Schema types that were changed in a way that was backwards compatible,
    // but invalidated the index. Represented by the `schema_type` field in the
    // SchemaTypeConfigProto.
    std::unordered_set<std::string> schema_types_index_incompatible;

    // Schema types that were changed in a way that was backwards compatible,
    // but invalidated the joinable cache. Represented by the `schema_type`
    // field in the SchemaTypeConfigProto.
    std::unordered_set<std::string> schema_types_join_incompatible;

    bool operator==(const SchemaDelta& other) const {
      return schema_types_deleted == other.schema_types_deleted &&
             schema_types_incompatible == other.schema_types_incompatible &&
             schema_types_new == other.schema_types_new &&
             schema_types_changed_fully_compatible ==
                 other.schema_types_changed_fully_compatible &&
             schema_types_index_incompatible ==
                 other.schema_types_index_incompatible &&
             schema_types_join_incompatible ==
                 other.schema_types_join_incompatible;
    }
  };

  struct ParsedPropertyConfigs {
    // Mapping of property name to PropertyConfigProto
    std::unordered_map<std::string_view, const PropertyConfigProto*>
        property_config_map;

    // Properties that have an indexing config
    std::unordered_set<std::string_view> indexed_properties;

    // Properties that were REQUIRED
    std::unordered_set<std::string_view> required_properties;

    // Properties that have joinable config
    std::unordered_set<std::string_view> joinable_properties;

    // Properties that have DataType::DOCUMENT
    std::unordered_set<std::string_view> nested_document_properties;
  };

  // This function validates:
  //   1. SchemaTypeConfigProto.schema_type's must be unique
  //   2. Properties within one SchemaTypeConfigProto must be unique
  //   3. SchemaTypeConfigProtos.schema_type must be non-empty
  //   4. PropertyConfigProtos.property_name must be non-empty
  //   5. PropertyConfigProtos.property_name's must be unique within one
  //      SchemaTypeConfigProto
  //   6. PropertyConfigProtos.data_type cannot be UNKNOWN
  //   7. PropertyConfigProtos.data_type of DOCUMENT must also have a
  //      schema_type
  //   8. PropertyConfigProtos.cardinality cannot be UNKNOWN
  //   9. PropertyConfigProtos.schema_type's must correspond to a
  //      SchemaTypeConfigProto.schema_type
  //  10. Property names can only be alphanumeric.
  //  11. Any STRING data types have a valid string_indexing_config
  //  12. PropertyConfigProtos.joinable_config must be valid. See
  //      ValidateJoinableConfig for more details.
  //  13. Any PropertyConfigProtos with nested DOCUMENT data type must not have
  //      REPEATED cardinality if they reference a schema type containing
  //      joinable property.
  //  14. The schema definition cannot have invalid cycles. A cycle is invalid
  //      if:
  //      a. SchemaTypeConfigProto.parent_type definitions form an inheritance
  //         cycle.
  //      b. The schema's property definitions have schema_types that form a
  //         cycle, and all properties on the cycle declare
  //         DocumentIndexingConfig.index_nested_properties=true.
  //      c. The schema's property definitions have schema_types that form a
  //         cycle, and the cycle leads to an invalid joinable property config.
  //         This is the case if:
  //           i. Any type node in the cycle itself has a joinable proprty
  //              (property whose joinable config is not NONE), OR
  //          ii. Any type node in the cycle has a nested-type (direct or
  //              indirect) with a joinable property.
  //  15. For DOCUMENT data types, if
  //      DocumentIndexingConfig.indexable_nested_properties_list is non-empty,
  //      DocumentIndexingConfig.index_nested_properties must be false.
  //
  // Returns:
  //   On success, a dependent map from each types to their dependent types
  //   that depend on it directly or indirectly.
  //   ALREADY_EXISTS for case 1 and 2
  //   INVALID_ARGUMENT for 3-15
  static libtextclassifier3::StatusOr<DependentMap> Validate(
      const SchemaProto& schema, bool allow_circular_schema_definitions);

  // Builds a transitive inheritance map.
  //
  // Ex. Suppose we have a schema with four types A, B, C and D, and we have the
  // following direct inheritance relation.
  //
  // A -> B (A is the parent type of B)
  // B -> C (B is the parent type of C)
  // C -> D (C is the parent type of D)
  //
  // Then, the transitive inheritance map for this schema would be:
  //
  // A -> B, C, D
  // B -> C, D
  // C -> D
  //
  // RETURNS:
  //   On success, a transitive inheritance map of all types in the schema.
  //   INVALID_ARGUMENT if the inheritance graph contains a cycle.
  static libtextclassifier3::StatusOr<SchemaUtil::InheritanceMap>
  BuildTransitiveInheritanceGraph(const SchemaProto& schema);

  // Creates a mapping of schema type -> schema type config proto. The
  // type_config_map is cleared, and then each schema-type_config_proto pair is
  // placed in the given type_config_map parameter.
  static void BuildTypeConfigMap(const SchemaProto& schema,
                                 TypeConfigMap* type_config_map);

  // Parses the given type_config and returns a struct of easily-parseable
  // information about the properties.
  static ParsedPropertyConfigs ParsePropertyConfigs(
      const SchemaTypeConfigProto& type_config);

  // Computes the delta between the old and new schema. There are a few
  // differences that'll be reported:
  //   1. The derived index would be incompatible. This is held in
  //      `SchemaDelta.index_incompatible`.
  //   2. Some schema types existed in the old schema, but have been deleted
  //      from the new schema. This is held in
  //      `SchemaDelta.schema_types_deleted`
  //   3. A schema type's new definition would mean any existing data of the old
  //      definition is now incompatible.
  //   4. The derived join index would be incompatible. This is held in
  //      `SchemaDelta.join_incompatible`.
  //
  // For case 1, the two schemas would result in an incompatible index if:
  //   1.1. The new SchemaProto has a different set of indexed properties than
  //        the old SchemaProto.
  //
  // For case 3, the two schemas would result in incompatible data if:
  //   3.1. A SchemaTypeConfig exists in the old SchemaProto, but is not in the
  //        new SchemaProto
  //   3.2. A property exists in the old SchemaTypeConfig, but is not in the new
  //        SchemaTypeConfig
  //   3.3. A property in the new SchemaTypeConfig and has a REQUIRED
  //        PropertyConfigProto.cardinality, but is not in the old
  //        SchemaTypeConfig
  //   3.4. A property is in both the old and new SchemaTypeConfig, but its
  //        PropertyConfigProto.data_type is different
  //   3.5. A property is in both the old and new SchemaTypeConfig, but its
  //        PropertyConfigProto.schema_type is different
  //   3.6. A property is in both the old and new SchemaTypeConfig, but its new
  //        PropertyConfigProto.cardinality is more restrictive. Restrictive
  //        scale defined as:
  //          LEAST <REPEATED - OPTIONAL - REQUIRED> MOST
  //
  // For case 4, the two schemas would result in an incompatible join if:
  //   4.1. A SchematypeConfig exists in the new SchemaProto that has a
  //        different set of joinable properties than it did in the old
  //        SchemaProto.
  //
  // A property is defined by the combination of the
  // SchemaTypeConfig.schema_type and the PropertyConfigProto.property_name.
  //
  // Returns a SchemaDelta that captures the aforementioned differences.
  static const SchemaDelta ComputeCompatibilityDelta(
      const SchemaProto& old_schema, const SchemaProto& new_schema,
      const DependentMap& new_schema_dependent_map);

  // Validates the 'property_name' field.
  //   1. Can't be an empty string
  //   2. Can only contain alphanumeric characters
  //
  // NOTE: schema_type is only used for logging. It is not necessary to populate
  // it.
  //
  // RETURNS:
  //   - OK if property_name is valid
  //   - INVALID_ARGUMENT if property name is empty or contains an
  //     non-alphabetic character.
  static libtextclassifier3::Status ValidatePropertyName(
      std::string_view property_name, std::string_view schema_type = "");

  static bool IsIndexedProperty(const PropertyConfigProto& property_config);

 private:
  // Validates the 'schema_type' field
  //
  // Returns:
  //   INVALID_ARGUMENT if 'schema_type' is an empty string.
  //   OK on success
  static libtextclassifier3::Status ValidateSchemaType(
      std::string_view schema_type);

  // Validates the 'data_type' field.
  //
  // Returns:
  //   INVALID_ARGUMENT if it's UNKNOWN
  //   OK on success
  static libtextclassifier3::Status ValidateDataType(
      PropertyConfigProto::DataType::Code data_type,
      std::string_view schema_type, std::string_view property_name);

  // Validates the 'cardinality' field.
  //
  // Returns:
  //   INVALID_ARGUMENT if it's UNKNOWN
  //   OK on success
  static libtextclassifier3::Status ValidateCardinality(
      PropertyConfigProto::Cardinality::Code cardinality,
      std::string_view schema_type, std::string_view property_name);

  // Checks that the 'string_indexing_config' satisfies the following rules:
  //   1. Only STRING data types can be indexed
  //   2. An indexed property must have a valid tokenizer type
  //
  // Returns:
  //   INVALID_ARGUMENT if any of the rules are not followed
  //   OK on success
  static libtextclassifier3::Status ValidateStringIndexingConfig(
      const StringIndexingConfig& config,
      PropertyConfigProto::DataType::Code data_type,
      std::string_view schema_type, std::string_view property_name);

  // Checks that the 'joinable_config' satisfies the following rules:
  //   1. If the data type matches joinable value type
  //      a. Only STRING data types can use QUALIFIED_ID joinable value type
  //   2. Only QUALIFIED_ID joinable value type can have delete propagation
  //      enabled
  //   3. Any joinable property should have non-REPEATED cardinality
  //
  // Returns:
  //   INVALID_ARGUMENT if any of the rules are not followed
  //   OK on success
  static libtextclassifier3::Status ValidateJoinableConfig(
      const JoinableConfig& config,
      PropertyConfigProto::DataType::Code data_type,
      PropertyConfigProto::Cardinality::Code cardinality,
      std::string_view schema_type, std::string_view property_name);

  // Checks that the 'document_indexing_config' satisfies the following rule:
  //    1. If indexable_nested_properties is non-empty, index_nested_properties
  //       must be set to false.
  //
  // Returns:
  //   INVALID_ARGUMENT if any of the rules are not followed
  //   OK on success
  static libtextclassifier3::Status ValidateDocumentIndexingConfig(
      const DocumentIndexingConfig& config, std::string_view schema_type,
      std::string_view property_name);

  // Returns if 'parent_type' is a direct or indirect parent of 'child_type'.
  static bool IsParent(const SchemaUtil::InheritanceMap& inheritance_map,
                       std::string_view parent_type,
                       std::string_view child_type);

  // Returns if 'child_property_config' in a child type can override
  // 'parent_property_config' in the parent type.
  //
  // Let's assign 'child_property_config' a type T1 and 'parent_property_config'
  // a type T2 that captures information for their data_type, schema_type and
  // cardinalities, so that 'child_property_config' can override
  // 'parent_property_config' if and only if T1 <: T2, i.e. T1 is a subtype of
  // T2.
  //
  // Below are the rules for inferring subtype relations.
  // - T <: T for every type T.
  // - If U extends T, then U <: T.
  // - For every type T1, T2 and T3, if T1 <: T2 and T2 <: T3, then T1 <: T3.
  // - Optional<T> <: Repeated<T> for every type T.
  // - Required<T> <: Optional<T> for every type T.
  // - If T1 <: T2, then
  //   - Required<T1> <: Required<T2>
  //   - Optional<T1> <: Optional<T2>
  //   - Repeated<T1> <: Repeated<T2>
  //
  // We assume the Closed World Assumption (CWA), i.e. if T1 <: T2 cannot be
  // deduced from the above rules, then T1 is not a subtype of T2.
  static bool IsInheritedPropertyCompatible(
      const SchemaUtil::InheritanceMap& inheritance_map,
      const PropertyConfigProto& child_property_config,
      const PropertyConfigProto& parent_property_config);

  // Verifies that every child type's property set has included all compatible
  // properties from parent types, based on the following rule:
  //
  // - If a property "prop" of type T is in the parent, then the child type must
  //   also have "prop" that is of type U, such that U <: T, i.e. U is a subtype
  //   of T.
  //
  // RETURNS:
  //   Ok on validation success
  //   INVALID_ARGUMENT if an exception that violates the above validation rule
  //     is found.
  static libtextclassifier3::Status ValidateInheritedProperties(
      const SchemaProto& schema);
};

}  // namespace lib
}  // namespace icing

#endif  // ICING_SCHEMA_SCHEMA_UTIL_H_