cpp/src/reader/tsfile_series_scan_iterator.cc - tsfile - Git at Google

 /*
  * Licensed to the Apache Software Foundation (ASF) under one
  * or more contributor license agreements.  See the NOTICE file
  * distributed with this work for additional information
  * regarding copyright ownership.  The ASF licenses this file
  * 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, 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 "reader/tsfile_series_scan_iterator.h"

 #include <iostream>

 #include "common/global.h"
 #ifdef ENABLE_THREADS
 #include "common/thread_pool.h"
 #endif

 using namespace common;

 namespace storage {

 void TsFileSeriesScanIterator::destroy() {
     // MultiAlignedTimeseriesIndex is placement-new'd inside
     // timeseries_index_pa_ (see TsFileIOReader::alloc_multi_ssi).  The arena's
     // destroy() frees raw memory without running destructors, so its
     // value_ts_idxs_ std::vector backing buffer would leak.  Release it
     // explicitly before tearing down the arena.  dynamic_cast is null-safe and
     // returns nullptr for the single-value / non-aligned index types, which own
     // no separate heap storage.
     if (auto* multi =
             dynamic_cast<MultiAlignedTimeseriesIndex*>(itimeseries_index_)) {
         std::vector<TimeseriesIndex*>().swap(multi->value_ts_idxs_);
     }
     itimeseries_index_ = nullptr;
     timeseries_index_pa_.destroy();
     if (chunk_reader_ != nullptr) {
         // destroy() already runs manual destructors on internal members
         // (chunk_header_, decoders, compressor, ...), so calling
         // chunk_reader_->~IChunkReader() here would double-destruct them.
         // The vector-buffer leaks (e.g. chunk_pages_) are released inside
         // AlignedChunkReader::destroy() via vector<>{}.swap().
         chunk_reader_->destroy();
         common::mem_free(chunk_reader_);
         chunk_reader_ = nullptr;
     }
     if (tsblock_ != nullptr) {
         tsblock_->~TsBlock();
         tsblock_ = nullptr;
     }
     // This SSI is placement-new'd into mem_alloc'd memory and torn down with
     // destroy() + mem_free() (see TsFileIOReader::revert_ssi / alloc_*_ssi),
     // so ~TsFileSeriesScanIterator() never runs and the heap-owning members
     // below would leak their backing storage on every query.  Release them
     // explicitly (after the TsBlock that pointed at tuple_desc_ is gone).
     tuple_desc_.release();
     std::vector<common::SimpleList<ChunkMeta*>::Iterator>().swap(
         value_chunk_meta_cursors_);
     device_id_.reset();
     std::string().swap(measurement_name_);
 }

 bool TsFileSeriesScanIterator::should_skip_chunk_by_time(
     ChunkMeta* cm, int64_t min_time_hint) {
     if (min_time_hint == std::numeric_limits<int64_t>::min() ||
         cm->statistic_ == nullptr) {
         return false;
     }
     return cm->statistic_->end_time_ < min_time_hint;
 }

 bool TsFileSeriesScanIterator::should_skip_chunk_by_offset(ChunkMeta* cm) {
     if (row_offset_ <= 0) {
         return false;
     }
     if (cm->statistic_ == nullptr || cm->statistic_->count_ == 0) {
         return false;
     }
     int32_t count = cm->statistic_->count_;
     if (row_offset_ >= count) {
         row_offset_ -= count;
         return true;
     }
     return false;
 }

 bool TsFileSeriesScanIterator::should_skip_aligned_chunk_by_offset(
     ChunkMeta* time_cm, ChunkMeta* value_cm) {
     if (row_offset_ <= 0) {
         return false;
     }
     // Aligned value chunks' statistic_->count_ only counts non-null rows,
     // not total rows.  Using value_cm alone could skip an entire 100-row
     // chunk for an offset of 10 just because it has 10 non-null values.
     // Only apply the whole-chunk shortcut when time and value statistics
     // agree on the row count (i.e. no sparse nulls in this chunk); fall
     // through to per-page/per-row handling otherwise so the offset is
     // applied against the real row stream.
     if (time_cm == nullptr || value_cm == nullptr ||
         time_cm->statistic_ == nullptr || value_cm->statistic_ == nullptr) {
         return false;
     }
     int32_t tc = time_cm->statistic_->count_;
     int32_t vc = value_cm->statistic_->count_;
     if (tc <= 0 || vc <= 0 || tc != vc) {
         return false;
     }
     if (row_offset_ >= tc) {
         row_offset_ -= tc;
         return true;
     }
     return false;
 }

 int TsFileSeriesScanIterator::get_next(TsBlock*& ret_tsblock, bool alloc,
                                        Filter* oneshoot_filter,
                                        int64_t min_time_hint) {
     int ret = E_OK;
     Filter* filter =
         (oneshoot_filter != nullptr) ? oneshoot_filter : time_filter_;

     // When get_next_page() reports E_NO_MORE_DATA but the chunk reader
     // still claims has_more_data() (an aligned-chunk artifact where time
     // and value pages report state differently), a bare `continue` would
     // retry the exhausted chunk forever.  Force the next iteration to
     // advance to the next chunk-meta cursor instead.
     bool force_load_next_chunk = false;
     while (true) {
         if (!chunk_reader_->has_more_data() || force_load_next_chunk) {
             force_load_next_chunk = false;
             while (true) {
                 if (!has_next_chunk()) {
                     return E_NO_MORE_DATA;
                 } else if (is_multi_value_) {
                     // Multi-value aligned path
                     ChunkMeta* time_cm = time_chunk_meta_cursor_.get();
                     std::vector<ChunkMeta*> value_cms;
                     value_cms.reserve(value_chunk_meta_cursors_.size());
                     for (auto& cur : value_chunk_meta_cursors_) {
                         value_cms.push_back(cur.get());
                     }
                     advance_to_next_chunk();
                     // Skip chunk by time filter using time chunk statistics.
                     if (filter != nullptr && time_cm->statistic_ != nullptr &&
                         !filter->satisfy(time_cm->statistic_)) {
                         continue;
                     }
                     if (should_skip_chunk_by_time(time_cm, min_time_hint)) {
                         continue;
                     }
                     chunk_reader_->reset();
                     auto* acr = static_cast<AlignedChunkReader*>(chunk_reader_);
                     if (RET_FAIL(acr->load_by_aligned_meta_multi(time_cm,
                                                                  value_cms))) {
                     }
                     break;
                 } else if (!is_aligned_) {
                     ChunkMeta* cm = get_current_chunk_meta();
                     advance_to_next_chunk();
                     if (filter != nullptr && cm->statistic_ != nullptr &&
                         !filter->satisfy(cm->statistic_)) {
                         continue;
                     }
                     // Skip by min_time_hint (merge cursor).
                     if (should_skip_chunk_by_time(cm, min_time_hint)) {
                         continue;
                     }
                     // Single-path: skip entire chunk by offset using count.
                     if (should_skip_chunk_by_offset(cm)) {
                         continue;
                     }
                     chunk_reader_->reset();
                     if (RET_FAIL(chunk_reader_->load_by_meta(cm))) {
                     }
                     break;
                 } else {
                     ChunkMeta* value_cm = value_chunk_meta_cursor_.get();
                     ChunkMeta* time_cm = time_chunk_meta_cursor_.get();
                     advance_to_next_chunk();
                     // Use time chunk statistics for time-based filtering.
                     ChunkMeta* filter_cm =
                         (time_cm->statistic_ != nullptr) ? time_cm : value_cm;
                     if (filter != nullptr && filter_cm->statistic_ != nullptr &&
                         !filter->satisfy(filter_cm->statistic_)) {
                         continue;
                     }
                     if (should_skip_chunk_by_time(filter_cm, min_time_hint)) {
                         continue;
                     }
                     if (should_skip_aligned_chunk_by_offset(time_cm,
                                                             value_cm)) {
                         continue;
                     }
                     chunk_reader_->reset();
                     if (RET_FAIL(chunk_reader_->load_by_aligned_meta(
                             time_cm, value_cm))) {
                     }
                     break;
                 }
             }
         }
         if (IS_SUCC(ret)) {
             if (alloc && ret_tsblock == nullptr) {
                 ret_tsblock =
                     is_multi_value_ ? alloc_tsblock_multi() : alloc_tsblock();
             }
             ret = chunk_reader_->get_next_page(ret_tsblock, filter, *data_pa_,
                                                min_time_hint, row_offset_,
                                                row_limit_);
         }
         if (ret == common::E_NO_MORE_DATA && ret_tsblock != nullptr &&
             ret_tsblock->get_row_count() > 0) {
             return E_OK;
         }
         // When current chunk is exhausted (e.g. all pages skipped by offset)
         // but there are more chunks, load next chunk and retry.  Set the
         // force flag so the next iteration bypasses has_more_data() (which
         // can still report true on an aligned chunk that has actually
         // yielded all its rows).
         if (ret == common::E_NO_MORE_DATA && has_next_chunk()) {
             ret = E_OK;
             force_load_next_chunk = true;
             continue;
         }
         return ret;
     }
 }

 void TsFileSeriesScanIterator::revert_tsblock() {
     if (tsblock_ == nullptr) {
         return;
     }
     tsblock_->~TsBlock();
     tsblock_ = nullptr;
 }

 int TsFileSeriesScanIterator::init_chunk_reader() {
     int ret = E_OK;
     is_aligned_ = itimeseries_index_->is_aligned();

     // Check if this is a multi-value aligned index. alloc_multi_ssi() creates
     // MultiAlignedTimeseriesIndex even when the query selects one value column,
     // so keep that path consistent with wider aligned reads.
     if (is_aligned_ && dynamic_cast<MultiAlignedTimeseriesIndex*>(
                            itimeseries_index_) != nullptr) {
         return init_chunk_reader_multi();
     }

     if (!is_aligned_) {
         void* buf =
             common::mem_alloc(sizeof(ChunkReader), common::MOD_CHUNK_READER);
         if (IS_NULL(buf)) return E_OOM;
         chunk_reader_ = new (buf) ChunkReader;
         chunk_meta_cursor_ = itimeseries_index_->get_chunk_meta_list()->begin();
         if (RET_FAIL(chunk_reader_->init(
                 read_file_, itimeseries_index_->get_measurement_name(),
                 itimeseries_index_->get_data_type(), time_filter_))) {
         }
     } else {
         void* buf = common::mem_alloc(sizeof(AlignedChunkReader),
                                       common::MOD_CHUNK_READER);
         if (IS_NULL(buf)) return E_OOM;
         chunk_reader_ = new (buf) AlignedChunkReader;
         time_chunk_meta_cursor_ =
             itimeseries_index_->get_time_chunk_meta_list()->begin();
         value_chunk_meta_cursor_ =
             itimeseries_index_->get_value_chunk_meta_list()->begin();
         if (RET_FAIL(chunk_reader_->init(
                 read_file_, itimeseries_index_->get_measurement_name(),
                 itimeseries_index_->get_data_type(), time_filter_))) {
         }
     }

     return ret;
 }

 int TsFileSeriesScanIterator::init_chunk_reader_multi() {
     int ret = E_OK;
     is_multi_value_ = true;

     void* buf =
         common::mem_alloc(sizeof(AlignedChunkReader), common::MOD_CHUNK_READER);
     if (IS_NULL(buf)) {
         // The single-value path (init_chunk_reader) silently dereferenced
         // the null pointer on OOM; this path is new in the multi-value
         // reader work and would do the same via placement-new(nullptr) →
         // undefined behavior the moment any AlignedChunkReader field is
         // touched.  Surface E_OOM instead.
         is_multi_value_ = false;
         return E_OOM;
     }
     auto* acr = new (buf) AlignedChunkReader;
     chunk_reader_ = acr;

     uint32_t num_cols = itimeseries_index_->get_value_column_count();
 #ifdef ENABLE_THREADS
     // Borrow the single process-wide worker pool (created in init_common()) for
     // multi-column decode.  Null when libtsfile_init() hasn't run; combined
     // with parallel_read_enabled_ this gates the parallel decode path — the
     // reader falls back to serial decode otherwise.
     if (num_cols > 1 && common::g_config_value_.parallel_read_enabled_ &&
         common::g_thread_pool_ != nullptr) {
         acr->set_decode_pool(common::g_thread_pool_);
     }
 #endif

     // Per-column chunk lists must align 1:1 with the time chunk list:
     // load_by_aligned_meta_multi pairs them by index and the downstream
     // reader has no notion of a "missing" value chunk for a CGM.  If a
     // file evolved its schema and some column has fewer (or more) chunks
     // than the time column, naive index pairing would mate chunks from
     // different chunk groups, returning garbage and dereferencing past
     // end() once the shorter list ran out.  Refuse upfront with a clear
     // error rather than producing wrong data.
     uint32_t time_chunk_count =
         itimeseries_index_->get_time_chunk_meta_list()->size();
     for (uint32_t c = 0; c < num_cols; c++) {
         if (itimeseries_index_->get_value_chunk_meta_list(c)->size() !=
             time_chunk_count) {
             return E_NOT_SUPPORT;
         }
     }

     // Init time cursor
     time_chunk_meta_cursor_ =
         itimeseries_index_->get_time_chunk_meta_list()->begin();

     // Init all value cursors
     value_chunk_meta_cursors_.resize(num_cols);
     for (uint32_t c = 0; c < num_cols; c++) {
         value_chunk_meta_cursors_[c] =
             itimeseries_index_->get_value_chunk_meta_list(c)->begin();
     }

     // Init chunk reader
     if (RET_FAIL(
             acr->init(read_file_, itimeseries_index_->get_measurement_name(),
                       itimeseries_index_->get_data_type(), time_filter_))) {
         return ret;
     }

     // No chunks → nothing to load; iteration short-circuits via
     // has_next_chunk() returning false.
     if (time_chunk_count == 0) {
         return ret;
     }

     // Load first chunk set
     ChunkMeta* time_cm = time_chunk_meta_cursor_.get();
     std::vector<ChunkMeta*> value_cms;
     value_cms.reserve(num_cols);
     for (uint32_t c = 0; c < num_cols; c++) {
         value_cms.push_back(value_chunk_meta_cursors_[c].get());
     }

     if (RET_FAIL(acr->load_by_aligned_meta_multi(time_cm, value_cms))) {
         return ret;
     }

     // Advance cursors
     time_chunk_meta_cursor_++;
     for (auto& cur : value_chunk_meta_cursors_) cur++;

     return ret;
 }

 TsBlock* TsFileSeriesScanIterator::alloc_tsblock() {
     ChunkHeader& ch = chunk_reader_->get_chunk_header();

     // Encoding/compression are unused for the in-memory result TsBlock;
     // only data_type (INT64) matters here.
     ColumnSchema time_cd("time", common::INT64, common::INVALID_COMPRESSION,
                          common::INVALID_ENCODING);
     ColumnSchema value_cd(ch.measurement_name_, ch.data_type_,
                           ch.compression_type_, ch.encoding_type_);

     // Reset first: this is called once per get_next(), and TsBlock holds a
     // pointer to tuple_desc_.  Without the reset, columns from previous calls
     // accumulate (each new block would carry duplicated columns and a
     // reallocated descriptor), corrupting the block layout.
     tuple_desc_.reset();
     tuple_desc_.push_back(time_cd);
     tuple_desc_.push_back(value_cd);

     void* tsblock_buf = data_pa_->alloc(sizeof(TsBlock));
     if (IS_NULL(tsblock_buf)) return nullptr;
     tsblock_ = new (tsblock_buf) TsBlock(&tuple_desc_);
     if (E_OK != tsblock_->init()) {
         tsblock_->~TsBlock();
         tsblock_ = nullptr;
     }
     return tsblock_;
 }

 TsBlock* TsFileSeriesScanIterator::alloc_tsblock_multi() {
     auto* acr = static_cast<AlignedChunkReader*>(chunk_reader_);

     // Encoding/compression are unused for the in-memory result TsBlock;
     // only data_type (INT64) matters here.
     ColumnSchema time_cd("time", common::INT64, common::INVALID_COMPRESSION,
                          common::INVALID_ENCODING);
     // Reset first (see alloc_tsblock): tuple_desc_ is reused across get_next()
     // calls and TsBlock holds a pointer to it, so stale columns must be
     // cleared.
     tuple_desc_.reset();
     tuple_desc_.push_back(time_cd);

     // Value columns
     uint32_t num_cols = acr->get_value_column_count();
     for (uint32_t c = 0; c < num_cols; c++) {
         ChunkHeader& ch = acr->get_value_chunk_header(c);
         ColumnSchema value_cd(ch.measurement_name_, ch.data_type_,
                               ch.compression_type_, ch.encoding_type_);
         tuple_desc_.push_back(value_cd);
     }

     void* tsblock_buf = data_pa_->alloc(sizeof(TsBlock));
     if (IS_NULL(tsblock_buf)) return nullptr;
     tsblock_ = new (tsblock_buf) TsBlock(&tuple_desc_);
     if (E_OK != tsblock_->init()) {
         tsblock_->~TsBlock();
         tsblock_ = nullptr;
     }
     return tsblock_;
 }

 }  // end namespace storage
	/*
	* Licensed to the Apache Software Foundation (ASF) under one
	* or more contributor license agreements. See the NOTICE file
	* distributed with this work for additional information
	* regarding copyright ownership. The ASF licenses this file
	* 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, 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 "reader/tsfile_series_scan_iterator.h"

	#include <iostream>

	#include "common/global.h"
	#ifdef ENABLE_THREADS
	#include "common/thread_pool.h"
	#endif

	using namespace common;

	namespace storage {

	void TsFileSeriesScanIterator::destroy() {
	// MultiAlignedTimeseriesIndex is placement-new'd inside
	// timeseries_index_pa_ (see TsFileIOReader::alloc_multi_ssi). The arena's
	// destroy() frees raw memory without running destructors, so its
	// value_ts_idxs_ std::vector backing buffer would leak. Release it
	// explicitly before tearing down the arena. dynamic_cast is null-safe and
	// returns nullptr for the single-value / non-aligned index types, which own
	// no separate heap storage.
	if (auto* multi =
	dynamic_cast<MultiAlignedTimeseriesIndex*>(itimeseries_index_)) {
	std::vector<TimeseriesIndex*>().swap(multi->value_ts_idxs_);
	}
	itimeseries_index_ = nullptr;
	timeseries_index_pa_.destroy();
	if (chunk_reader_ != nullptr) {
	// destroy() already runs manual destructors on internal members
	// (chunk_header_, decoders, compressor, ...), so calling
	// chunk_reader_->~IChunkReader() here would double-destruct them.
	// The vector-buffer leaks (e.g. chunk_pages_) are released inside
	// AlignedChunkReader::destroy() via vector<>{}.swap().
	chunk_reader_->destroy();
	common::mem_free(chunk_reader_);
	chunk_reader_ = nullptr;
	}
	if (tsblock_ != nullptr) {
	tsblock_->~TsBlock();
	tsblock_ = nullptr;
	}
	// This SSI is placement-new'd into mem_alloc'd memory and torn down with
	// destroy() + mem_free() (see TsFileIOReader::revert_ssi / alloc_*_ssi),
	// so ~TsFileSeriesScanIterator() never runs and the heap-owning members
	// below would leak their backing storage on every query. Release them
	// explicitly (after the TsBlock that pointed at tuple_desc_ is gone).
	tuple_desc_.release();
	std::vector<common::SimpleList<ChunkMeta*>::Iterator>().swap(
	value_chunk_meta_cursors_);
	device_id_.reset();
	std::string().swap(measurement_name_);
	}

	bool TsFileSeriesScanIterator::should_skip_chunk_by_time(
	ChunkMeta* cm, int64_t min_time_hint) {
	if (min_time_hint == std::numeric_limits<int64_t>::min() \|\|
	cm->statistic_ == nullptr) {
	return false;
	}
	return cm->statistic_->end_time_ < min_time_hint;
	}

	bool TsFileSeriesScanIterator::should_skip_chunk_by_offset(ChunkMeta* cm) {
	if (row_offset_ <= 0) {
	return false;
	}
	if (cm->statistic_ == nullptr \|\| cm->statistic_->count_ == 0) {
	return false;
	}
	int32_t count = cm->statistic_->count_;
	if (row_offset_ >= count) {
	row_offset_ -= count;
	return true;
	}
	return false;
	}

	bool TsFileSeriesScanIterator::should_skip_aligned_chunk_by_offset(
	ChunkMeta* time_cm, ChunkMeta* value_cm) {
	if (row_offset_ <= 0) {
	return false;
	}
	// Aligned value chunks' statistic_->count_ only counts non-null rows,
	// not total rows. Using value_cm alone could skip an entire 100-row
	// chunk for an offset of 10 just because it has 10 non-null values.
	// Only apply the whole-chunk shortcut when time and value statistics
	// agree on the row count (i.e. no sparse nulls in this chunk); fall
	// through to per-page/per-row handling otherwise so the offset is
	// applied against the real row stream.
	if (time_cm == nullptr \|\| value_cm == nullptr \|\|
	time_cm->statistic_ == nullptr \|\| value_cm->statistic_ == nullptr) {
	return false;
	}
	int32_t tc = time_cm->statistic_->count_;
	int32_t vc = value_cm->statistic_->count_;
	if (tc <= 0 \|\| vc <= 0 \|\| tc != vc) {
	return false;
	}
	if (row_offset_ >= tc) {
	row_offset_ -= tc;
	return true;
	}
	return false;
	}

	int TsFileSeriesScanIterator::get_next(TsBlock*& ret_tsblock, bool alloc,
	Filter* oneshoot_filter,
	int64_t min_time_hint) {
	int ret = E_OK;
	Filter* filter =
	(oneshoot_filter != nullptr) ? oneshoot_filter : time_filter_;

	// When get_next_page() reports E_NO_MORE_DATA but the chunk reader
	// still claims has_more_data() (an aligned-chunk artifact where time
	// and value pages report state differently), a bare `continue` would
	// retry the exhausted chunk forever. Force the next iteration to
	// advance to the next chunk-meta cursor instead.
	bool force_load_next_chunk = false;
	while (true) {
	if (!chunk_reader_->has_more_data() \|\| force_load_next_chunk) {
	force_load_next_chunk = false;
	while (true) {
	if (!has_next_chunk()) {
	return E_NO_MORE_DATA;
	} else if (is_multi_value_) {
	// Multi-value aligned path
	ChunkMeta* time_cm = time_chunk_meta_cursor_.get();
	std::vector<ChunkMeta*> value_cms;
	value_cms.reserve(value_chunk_meta_cursors_.size());
	for (auto& cur : value_chunk_meta_cursors_) {
	value_cms.push_back(cur.get());
	}
	advance_to_next_chunk();
	// Skip chunk by time filter using time chunk statistics.
	if (filter != nullptr && time_cm->statistic_ != nullptr &&
	!filter->satisfy(time_cm->statistic_)) {
	continue;
	}
	if (should_skip_chunk_by_time(time_cm, min_time_hint)) {
	continue;
	}
	chunk_reader_->reset();
	auto* acr = static_cast<AlignedChunkReader*>(chunk_reader_);
	if (RET_FAIL(acr->load_by_aligned_meta_multi(time_cm,
	value_cms))) {
	}
	break;
	} else if (!is_aligned_) {
	ChunkMeta* cm = get_current_chunk_meta();
	advance_to_next_chunk();
	if (filter != nullptr && cm->statistic_ != nullptr &&
	!filter->satisfy(cm->statistic_)) {
	continue;
	}
	// Skip by min_time_hint (merge cursor).
	if (should_skip_chunk_by_time(cm, min_time_hint)) {
	continue;
	}
	// Single-path: skip entire chunk by offset using count.
	if (should_skip_chunk_by_offset(cm)) {
	continue;
	}
	chunk_reader_->reset();
	if (RET_FAIL(chunk_reader_->load_by_meta(cm))) {
	}
	break;
	} else {
	ChunkMeta* value_cm = value_chunk_meta_cursor_.get();
	ChunkMeta* time_cm = time_chunk_meta_cursor_.get();
	advance_to_next_chunk();
	// Use time chunk statistics for time-based filtering.
	ChunkMeta* filter_cm =
	(time_cm->statistic_ != nullptr) ? time_cm : value_cm;
	if (filter != nullptr && filter_cm->statistic_ != nullptr &&
	!filter->satisfy(filter_cm->statistic_)) {
	continue;
	}
	if (should_skip_chunk_by_time(filter_cm, min_time_hint)) {
	continue;
	}
	if (should_skip_aligned_chunk_by_offset(time_cm,
	value_cm)) {
	continue;
	}
	chunk_reader_->reset();
	if (RET_FAIL(chunk_reader_->load_by_aligned_meta(
	time_cm, value_cm))) {
	}
	break;
	}
	}
	}
	if (IS_SUCC(ret)) {
	if (alloc && ret_tsblock == nullptr) {
	ret_tsblock =
	is_multi_value_ ? alloc_tsblock_multi() : alloc_tsblock();
	}
	ret = chunk_reader_->get_next_page(ret_tsblock, filter, *data_pa_,
	min_time_hint, row_offset_,
	row_limit_);
	}
	if (ret == common::E_NO_MORE_DATA && ret_tsblock != nullptr &&
	ret_tsblock->get_row_count() > 0) {
	return E_OK;
	}
	// When current chunk is exhausted (e.g. all pages skipped by offset)
	// but there are more chunks, load next chunk and retry. Set the
	// force flag so the next iteration bypasses has_more_data() (which
	// can still report true on an aligned chunk that has actually
	// yielded all its rows).
	if (ret == common::E_NO_MORE_DATA && has_next_chunk()) {
	ret = E_OK;
	force_load_next_chunk = true;
	continue;
	}
	return ret;
	}
	}

	void TsFileSeriesScanIterator::revert_tsblock() {
	if (tsblock_ == nullptr) {
	return;
	}
	tsblock_->~TsBlock();
	tsblock_ = nullptr;
	}

	int TsFileSeriesScanIterator::init_chunk_reader() {
	int ret = E_OK;
	is_aligned_ = itimeseries_index_->is_aligned();

	// Check if this is a multi-value aligned index. alloc_multi_ssi() creates
	// MultiAlignedTimeseriesIndex even when the query selects one value column,
	// so keep that path consistent with wider aligned reads.
	if (is_aligned_ && dynamic_cast<MultiAlignedTimeseriesIndex*>(
	itimeseries_index_) != nullptr) {
	return init_chunk_reader_multi();
	}

	if (!is_aligned_) {
	void* buf =
	common::mem_alloc(sizeof(ChunkReader), common::MOD_CHUNK_READER);
	if (IS_NULL(buf)) return E_OOM;
	chunk_reader_ = new (buf) ChunkReader;
	chunk_meta_cursor_ = itimeseries_index_->get_chunk_meta_list()->begin();
	if (RET_FAIL(chunk_reader_->init(
	read_file_, itimeseries_index_->get_measurement_name(),
	itimeseries_index_->get_data_type(), time_filter_))) {
	}
	} else {
	void* buf = common::mem_alloc(sizeof(AlignedChunkReader),
	common::MOD_CHUNK_READER);
	if (IS_NULL(buf)) return E_OOM;
	chunk_reader_ = new (buf) AlignedChunkReader;
	time_chunk_meta_cursor_ =
	itimeseries_index_->get_time_chunk_meta_list()->begin();
	value_chunk_meta_cursor_ =
	itimeseries_index_->get_value_chunk_meta_list()->begin();
	if (RET_FAIL(chunk_reader_->init(
	read_file_, itimeseries_index_->get_measurement_name(),
	itimeseries_index_->get_data_type(), time_filter_))) {
	}
	}

	return ret;
	}

	int TsFileSeriesScanIterator::init_chunk_reader_multi() {
	int ret = E_OK;
	is_multi_value_ = true;

	void* buf =
	common::mem_alloc(sizeof(AlignedChunkReader), common::MOD_CHUNK_READER);
	if (IS_NULL(buf)) {
	// The single-value path (init_chunk_reader) silently dereferenced
	// the null pointer on OOM; this path is new in the multi-value
	// reader work and would do the same via placement-new(nullptr) →
	// undefined behavior the moment any AlignedChunkReader field is
	// touched. Surface E_OOM instead.
	is_multi_value_ = false;
	return E_OOM;
	}
	auto* acr = new (buf) AlignedChunkReader;
	chunk_reader_ = acr;

	uint32_t num_cols = itimeseries_index_->get_value_column_count();
	#ifdef ENABLE_THREADS
	// Borrow the single process-wide worker pool (created in init_common()) for
	// multi-column decode. Null when libtsfile_init() hasn't run; combined
	// with parallel_read_enabled_ this gates the parallel decode path — the
	// reader falls back to serial decode otherwise.
	if (num_cols > 1 && common::g_config_value_.parallel_read_enabled_ &&
	common::g_thread_pool_ != nullptr) {
	acr->set_decode_pool(common::g_thread_pool_);
	}
	#endif

	// Per-column chunk lists must align 1:1 with the time chunk list:
	// load_by_aligned_meta_multi pairs them by index and the downstream
	// reader has no notion of a "missing" value chunk for a CGM. If a
	// file evolved its schema and some column has fewer (or more) chunks
	// than the time column, naive index pairing would mate chunks from
	// different chunk groups, returning garbage and dereferencing past
	// end() once the shorter list ran out. Refuse upfront with a clear
	// error rather than producing wrong data.
	uint32_t time_chunk_count =
	itimeseries_index_->get_time_chunk_meta_list()->size();
	for (uint32_t c = 0; c < num_cols; c++) {
	if (itimeseries_index_->get_value_chunk_meta_list(c)->size() !=
	time_chunk_count) {
	return E_NOT_SUPPORT;
	}
	}

	// Init time cursor
	time_chunk_meta_cursor_ =
	itimeseries_index_->get_time_chunk_meta_list()->begin();

	// Init all value cursors
	value_chunk_meta_cursors_.resize(num_cols);
	for (uint32_t c = 0; c < num_cols; c++) {
	value_chunk_meta_cursors_[c] =
	itimeseries_index_->get_value_chunk_meta_list(c)->begin();
	}

	// Init chunk reader
	if (RET_FAIL(
	acr->init(read_file_, itimeseries_index_->get_measurement_name(),
	itimeseries_index_->get_data_type(), time_filter_))) {
	return ret;
	}

	// No chunks → nothing to load; iteration short-circuits via
	// has_next_chunk() returning false.
	if (time_chunk_count == 0) {
	return ret;
	}

	// Load first chunk set
	ChunkMeta* time_cm = time_chunk_meta_cursor_.get();
	std::vector<ChunkMeta*> value_cms;
	value_cms.reserve(num_cols);
	for (uint32_t c = 0; c < num_cols; c++) {
	value_cms.push_back(value_chunk_meta_cursors_[c].get());
	}

	if (RET_FAIL(acr->load_by_aligned_meta_multi(time_cm, value_cms))) {
	return ret;
	}

	// Advance cursors
	time_chunk_meta_cursor_++;
	for (auto& cur : value_chunk_meta_cursors_) cur++;

	return ret;
	}

	TsBlock* TsFileSeriesScanIterator::alloc_tsblock() {
	ChunkHeader& ch = chunk_reader_->get_chunk_header();

	// Encoding/compression are unused for the in-memory result TsBlock;
	// only data_type (INT64) matters here.
	ColumnSchema time_cd("time", common::INT64, common::INVALID_COMPRESSION,
	common::INVALID_ENCODING);
	ColumnSchema value_cd(ch.measurement_name_, ch.data_type_,
	ch.compression_type_, ch.encoding_type_);

	// Reset first: this is called once per get_next(), and TsBlock holds a
	// pointer to tuple_desc_. Without the reset, columns from previous calls
	// accumulate (each new block would carry duplicated columns and a
	// reallocated descriptor), corrupting the block layout.
	tuple_desc_.reset();
	tuple_desc_.push_back(time_cd);
	tuple_desc_.push_back(value_cd);

	void* tsblock_buf = data_pa_->alloc(sizeof(TsBlock));
	if (IS_NULL(tsblock_buf)) return nullptr;
	tsblock_ = new (tsblock_buf) TsBlock(&tuple_desc_);
	if (E_OK != tsblock_->init()) {
	tsblock_->~TsBlock();
	tsblock_ = nullptr;
	}
	return tsblock_;
	}

	TsBlock* TsFileSeriesScanIterator::alloc_tsblock_multi() {
	auto* acr = static_cast<AlignedChunkReader*>(chunk_reader_);

	// Encoding/compression are unused for the in-memory result TsBlock;
	// only data_type (INT64) matters here.
	ColumnSchema time_cd("time", common::INT64, common::INVALID_COMPRESSION,
	common::INVALID_ENCODING);
	// Reset first (see alloc_tsblock): tuple_desc_ is reused across get_next()
	// calls and TsBlock holds a pointer to it, so stale columns must be
	// cleared.
	tuple_desc_.reset();
	tuple_desc_.push_back(time_cd);

	// Value columns
	uint32_t num_cols = acr->get_value_column_count();
	for (uint32_t c = 0; c < num_cols; c++) {
	ChunkHeader& ch = acr->get_value_chunk_header(c);
	ColumnSchema value_cd(ch.measurement_name_, ch.data_type_,
	ch.compression_type_, ch.encoding_type_);
	tuple_desc_.push_back(value_cd);
	}

	void* tsblock_buf = data_pa_->alloc(sizeof(TsBlock));
	if (IS_NULL(tsblock_buf)) return nullptr;
	tsblock_ = new (tsblock_buf) TsBlock(&tuple_desc_);
	if (E_OK != tsblock_->init()) {
	tsblock_->~TsBlock();
	tsblock_ = nullptr;
	}
	return tsblock_;
	}

	} // end namespace storage