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// Copyright (C) 2022 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_INDEX_NUMERIC_POSTING_LIST_INTEGER_INDEX_ACCESSOR_H_
#define ICING_INDEX_NUMERIC_POSTING_LIST_INTEGER_INDEX_ACCESSOR_H_
#include <cstdint>
#include <memory>
#include <vector>
#include "icing/text_classifier/lib3/utils/base/status.h"
#include "icing/text_classifier/lib3/utils/base/statusor.h"
#include "icing/file/posting_list/flash-index-storage.h"
#include "icing/file/posting_list/posting-list-accessor.h"
#include "icing/file/posting_list/posting-list-identifier.h"
#include "icing/file/posting_list/posting-list-used.h"
#include "icing/index/numeric/integer-index-data.h"
#include "icing/index/numeric/posting-list-integer-index-serializer.h"
namespace icing {
namespace lib {
// TODO(b/259743562): Refactor PostingListAccessor derived classes
// This class is used to provide a simple abstraction for adding integer index
// data to posting lists. PostingListIntegerIndexAccessor handles:
// 1) selection of properly-sized posting lists for the accumulated integer
// index data during Finalize()
// 2) chaining of max-sized posting lists.
class PostingListIntegerIndexAccessor : public PostingListAccessor {
public:
// Creates an empty PostingListIntegerIndexAccessor.
//
// RETURNS:
// - On success, a valid instance of PostingListIntegerIndexAccessor
// - INVALID_ARGUMENT error if storage has an invalid block_size.
static libtextclassifier3::StatusOr<
std::unique_ptr<PostingListIntegerIndexAccessor>>
Create(FlashIndexStorage* storage,
PostingListIntegerIndexSerializer* serializer);
// Creates a PostingListIntegerIndexAccessor with an existing posting list
// identified by existing_posting_list_id.
//
// RETURNS:
// - On success, a valid instance of PostingListIntegerIndexAccessor
// - INVALID_ARGUMENT if storage has an invalid block_size.
static libtextclassifier3::StatusOr<
std::unique_ptr<PostingListIntegerIndexAccessor>>
CreateFromExisting(FlashIndexStorage* storage,
PostingListIntegerIndexSerializer* serializer,
PostingListIdentifier existing_posting_list_id);
PostingListSerializer* GetSerializer() override { return serializer_; }
// Retrieves the next batch of data in the posting list chain.
//
// RETURNS:
// - On success, a vector of integer index data in the posting list chain
// - FAILED_PRECONDITION_ERROR if called on an instance that was created via
// Create.
// - INTERNAL_ERROR if unable to read the next posting list in the chain or
// if the posting list has been corrupted somehow.
libtextclassifier3::StatusOr<std::vector<IntegerIndexData>>
GetNextDataBatch();
// Retrieves all data from the posting list chain and frees all posting
// list(s).
//
// RETURNS:
// - On success, a vector of integer index data in the posting list chain
// - FAILED_PRECONDITION_ERROR if called on an instance that was created via
// Create.
// - INTERNAL_ERROR if unable to read the next posting list in the chain or
// if the posting list has been corrupted somehow.
libtextclassifier3::StatusOr<std::vector<IntegerIndexData>>
GetAllDataAndFree();
// Prepends one data. This may result in flushing the posting list to disk (if
// the PostingListIntegerIndexAccessor holds a max-sized posting list that
// is full) or freeing a pre-existing posting list if it is too small to fit
// all data necessary.
//
// RETURNS:
// - OK, on success
// - INVALID_ARGUMENT if !data.is_valid() or if data is greater than the
// previously added data.
// - RESOURCE_EXHAUSTED error if unable to grow the index to allocate a new
// posting list.
libtextclassifier3::Status PrependData(const IntegerIndexData& data);
private:
explicit PostingListIntegerIndexAccessor(
FlashIndexStorage* storage, PostingListUsed in_memory_posting_list,
PostingListIntegerIndexSerializer* serializer)
: PostingListAccessor(storage, std::move(in_memory_posting_list)),
serializer_(serializer) {}
// Retrieves the next batch of data in the posting list chain.
//
// - free_posting_list: a boolean flag indicating whether freeing all posting
// lists after retrieving batch data.
//
// RETURNS:
// - On success, a vector of integer index data in the posting list chain
// - FAILED_PRECONDITION_ERROR if called on an instance that was created via
// Create.
// - INTERNAL_ERROR if unable to read the next posting list in the chain or
// if the posting list has been corrupted somehow.
libtextclassifier3::StatusOr<std::vector<IntegerIndexData>>
GetNextDataBatchImpl(bool free_posting_list);
PostingListIntegerIndexSerializer* serializer_; // Does not own.
};
} // namespace lib
} // namespace icing
#endif // ICING_INDEX_NUMERIC_POSTING_LIST_INTEGER_INDEX_ACCESSOR_H_
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