mirror of
https://github.com/facebook/rocksdb.git
synced 2026-07-07 14:47:40 +08:00
Andrew Chang
453ebd6f37
Summary: Pull Request resolved: https://github.com/facebook/rocksdb/pull/14510 When a filesystem does not return kAsyncIO in SupportedOps(), MultiScan still sends ReadAsync/Poll/AbortIO requests. Regular iterators check via CheckFSFeatureSupport in ArenaWrappedDBIter::Init and ForwardIterator, but MultiScan blindly trusted the caller-provided MultiScanArgs::use_async_io flag. Fix: In the MultiScan constructor, after scan_opts_ is initialized, check CheckFSFeatureSupport and disable use_async_io if the FS doesn't support it. Also pass the (potentially modified) scan_opts_ to Prepare() instead of the original scan_opts parameter. Reviewed By: mszeszko-meta Differential Revision: D97995735 fbshipit-source-id: 331639d950fd3cb9f491feed996d5820294beb4e
92 lines
3.2 KiB
C++
92 lines
3.2 KiB
C++
// Copyright (c) Meta Platforms, Inc. and affiliates.
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// This source code is licensed under both the GPLv2 (found in the
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// COPYING file in the root directory) and Apache 2.0 License
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// (found in the LICENSE.Apache file in the root directory).
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#include "file/file_util.h"
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#include "rocksdb/db.h"
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#include "rocksdb/file_system.h"
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namespace ROCKSDB_NAMESPACE {
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using MultiScanIterator = MultiScan::MultiScanIterator;
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MultiScan::MultiScan(const ReadOptions& read_options,
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const MultiScanArgs& scan_opts, DB* db,
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ColumnFamilyHandle* cfh)
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: read_options_(read_options),
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scan_opts_([&] {
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// Disable async IO if the filesystem does not support it, consistent
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// with how ArenaWrappedDBIter::Init() handles ReadOptions::async_io.
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auto opts = scan_opts;
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if (opts.use_async_io &&
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!CheckFSFeatureSupport(db->GetFileSystem(),
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FSSupportedOps::kAsyncIO)) {
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opts.use_async_io = false;
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}
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return opts;
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}()),
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db_(db),
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cfh_(cfh) {
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bool slow_path = false;
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// Setup read_options with iterate_uuper_bound based on the first scan.
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// Subsequent scans will update and allocate a new DB iterator as necessary
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if (scan_opts_.GetScanRanges()[0].range.limit) {
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upper_bound_ = *scan_opts_.GetScanRanges()[0].range.limit;
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read_options_.iterate_upper_bound = &upper_bound_;
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} else {
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read_options_.iterate_upper_bound = nullptr;
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}
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for (const auto& opts : scan_opts_.GetScanRanges()) {
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// Check that all the ScanOptions either specify an upper bound or not. If
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// its mixed we take the slow path which avoids calling Prepare: we have to
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// reallocate the Iterator with updated read_options everytime we switch
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// between upper bound or no upper bound, which complicates Prepare.
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if (opts.range.limit.has_value() !=
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scan_opts_.GetScanRanges()[0].range.limit.has_value()) {
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slow_path = true;
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break;
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}
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}
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db_iter_.reset(db->NewIterator(read_options_, cfh));
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if (!slow_path) {
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db_iter_->Prepare(scan_opts_);
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}
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}
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MultiScanIterator& MultiScanIterator::operator++() {
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status_ = db_iter_->status();
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if (!status_.ok()) {
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throw MultiScanException(status_);
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}
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if (idx_ >= scan_opts_.size()) {
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throw std::logic_error("Index out of range");
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}
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idx_++;
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if (idx_ < scan_opts_.size()) {
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// Check if we need to update read_options_
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if (scan_opts_[idx_].range.limit.has_value() !=
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(read_options_.iterate_upper_bound != nullptr)) {
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if (scan_opts_[idx_].range.limit) {
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*upper_bound_ = *scan_opts_[idx_].range.limit;
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read_options_.iterate_upper_bound = upper_bound_;
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} else {
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read_options_.iterate_upper_bound = nullptr;
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}
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db_iter_.reset(db_->NewIterator(read_options_, cfh_));
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scan_.Reset(db_iter_.get());
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} else if (scan_opts_[idx_].range.limit) {
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*upper_bound_ = *scan_opts_[idx_].range.limit;
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}
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db_iter_->Seek(*scan_opts_[idx_].range.start);
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status_ = db_iter_->status();
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if (!status_.ok()) {
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throw MultiScanException(status_);
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}
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}
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return *this;
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}
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} // namespace ROCKSDB_NAMESPACE
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