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// 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.
#include "icing/index/lite/doc-hit-info-iterator-term-lite.h"
#include <array>
#include <cstddef>
#include <cstdint>
#include <numeric>
#include "icing/text_classifier/lib3/utils/base/status.h"
#include "icing/absl_ports/canonical_errors.h"
#include "icing/absl_ports/str_cat.h"
#include "icing/index/hit/doc-hit-info.h"
#include "icing/schema/section.h"
#include "icing/util/logging.h"
#include "icing/util/status-macros.h"
namespace icing {
namespace lib {
namespace {
std::string SectionIdMaskToString(SectionIdMask section_id_mask) {
std::string mask(kTotalNumSections, '0');
for (SectionId i = kMaxSectionId; i >= 0; --i) {
if (section_id_mask & (UINT64_C(1) << i)) {
mask[kMaxSectionId - i] = '1';
}
}
return mask;
}
} // namespace
libtextclassifier3::Status DocHitInfoIteratorTermLite::Advance() {
if (cached_hits_idx_ == -1) {
libtextclassifier3::Status status = RetrieveMoreHits();
if (!status.ok()) {
if (!absl_ports::IsNotFound(status)) {
// NOT_FOUND is expected to happen (not every term will be in the main
// index!). Other errors are worth logging.
ICING_LOG(ERROR)
<< "Encountered unexpected failure while retrieving hits "
<< status.error_message();
}
return absl_ports::ResourceExhaustedError(
"No more DocHitInfos in iterator");
}
} else {
++cached_hits_idx_;
}
if (cached_hits_idx_ == -1 || cached_hits_idx_ >= cached_hits_.size()) {
// Nothing more for the iterator to return. Set these members to invalid
// values.
doc_hit_info_ = DocHitInfo();
return absl_ports::ResourceExhaustedError(
"No more DocHitInfos in iterator");
}
++num_advance_calls_;
doc_hit_info_ = cached_hits_.at(cached_hits_idx_);
return libtextclassifier3::Status::OK;
}
libtextclassifier3::StatusOr<DocHitInfoIterator::TrimmedNode>
DocHitInfoIteratorTermLite::TrimRightMostNode() && {
// Leaf iterator should trim itself.
DocHitInfoIterator::TrimmedNode node = {nullptr, term_, term_start_index_,
unnormalized_term_length_};
return node;
}
libtextclassifier3::Status DocHitInfoIteratorTermLiteExact::RetrieveMoreHits() {
// Exact match only. All hits in lite lexicon are exact.
ICING_ASSIGN_OR_RETURN(uint32_t tvi, lite_index_->GetTermId(term_));
ICING_ASSIGN_OR_RETURN(uint32_t term_id,
term_id_codec_->EncodeTvi(tvi, TviType::LITE));
lite_index_->FetchHits(
term_id, section_restrict_mask_,
/*only_from_prefix_sections=*/false,
/*score_by=*/
SuggestionScoringSpecProto::SuggestionRankingStrategy::NONE,
/*namespace_checker=*/nullptr, &cached_hits_,
need_hit_term_frequency_ ? &cached_hit_term_frequency_ : nullptr);
cached_hits_idx_ = 0;
return libtextclassifier3::Status::OK;
}
std::string DocHitInfoIteratorTermLiteExact::ToString() const {
return absl_ports::StrCat(SectionIdMaskToString(section_restrict_mask_), ":",
term_);
}
libtextclassifier3::Status
DocHitInfoIteratorTermLitePrefix::RetrieveMoreHits() {
// Take union of lite terms.
int term_len = term_.length();
int terms_matched = 0;
for (LiteIndex::PrefixIterator it = lite_index_->FindTermPrefixes(term_);
it.IsValid(); it.Advance()) {
bool exact_match = strlen(it.GetKey()) == term_len;
ICING_ASSIGN_OR_RETURN(
uint32_t term_id,
term_id_codec_->EncodeTvi(it.GetValueIndex(), TviType::LITE));
lite_index_->FetchHits(
term_id, section_restrict_mask_,
/*only_from_prefix_sections=*/!exact_match,
/*score_by=*/
SuggestionScoringSpecProto::SuggestionRankingStrategy::NONE,
/*namespace_checker=*/nullptr, &cached_hits_,
need_hit_term_frequency_ ? &cached_hit_term_frequency_ : nullptr);
++terms_matched;
}
if (terms_matched > 1) {
SortAndDedupeDocumentIds();
}
cached_hits_idx_ = 0;
return libtextclassifier3::Status::OK;
}
void DocHitInfoIteratorTermLitePrefix::SortDocumentIds() {
// Re-sort cached document_ids and merge sections.
if (!need_hit_term_frequency_) {
// If we don't need to also sort cached_hit_term_frequency_ along with
// cached_hits_, then just simply sort cached_hits_.
sort(cached_hits_.begin(), cached_hits_.end());
} else {
// Sort cached_hit_term_frequency_ along with cached_hits_.
std::vector<int> indices(cached_hits_.size());
std::iota(indices.begin(), indices.end(), 0);
std::sort(indices.begin(), indices.end(), [this](int i, int j) {
return cached_hits_[i] < cached_hits_[j];
});
// Now indices is a map from sorted index to current index. In other words,
// the sorted cached_hits_[i] should be the current cached_hits_[indices[i]]
// for every valid i.
std::vector<bool> done(indices.size());
// Apply permutation
for (int i = 0; i < indices.size(); ++i) {
if (done[i]) {
continue;
}
done[i] = true;
int curr = i;
int next = indices[i];
// Since every finite permutation is formed by disjoint cycles, we can
// start with the current element, at index i, and swap the element at
// this position with whatever element that *should* be here. Then,
// continue to swap the original element, at its updated positions, with
// the element that should be occupying that position until the original
// element has reached *its* correct position. This completes applying the
// single cycle in the permutation.
while (next != i) {
std::swap(cached_hits_[curr], cached_hits_[next]);
std::swap(cached_hit_term_frequency_[curr],
cached_hit_term_frequency_[next]);
done[next] = true;
curr = next;
next = indices[next];
}
}
}
}
void DocHitInfoIteratorTermLitePrefix::SortAndDedupeDocumentIds() {
SortDocumentIds();
int idx = 0;
for (int i = 1; i < cached_hits_.size(); ++i) {
const DocHitInfo& hit_info = cached_hits_[i];
DocHitInfo& collapsed_hit_info = cached_hits_[idx];
if (collapsed_hit_info.document_id() == hit_info.document_id()) {
SectionIdMask curr_mask = hit_info.hit_section_ids_mask();
collapsed_hit_info.MergeSectionsFrom(curr_mask);
if (need_hit_term_frequency_) {
Hit::TermFrequencyArray& collapsed_term_frequency =
cached_hit_term_frequency_[idx];
while (curr_mask) {
SectionId section_id = __builtin_ctzll(curr_mask);
collapsed_term_frequency[section_id] =
cached_hit_term_frequency_[i][section_id];
curr_mask &= ~(UINT64_C(1) << section_id);
}
}
} else {
// New document_id.
++idx;
cached_hits_[idx] = hit_info;
if (need_hit_term_frequency_) {
cached_hit_term_frequency_[idx] = cached_hit_term_frequency_[i];
}
}
}
// idx points to last doc hit info.
cached_hits_.resize(idx + 1);
if (need_hit_term_frequency_) {
cached_hit_term_frequency_.resize(idx + 1);
}
}
std::string DocHitInfoIteratorTermLitePrefix::ToString() const {
return absl_ports::StrCat(SectionIdMaskToString(section_restrict_mask_), ":",
term_, "*");
}
} // namespace lib
} // namespace icing
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