taiyang-li commented on code in PR #2048: URL: https://github.com/apache/orc/pull/2048#discussion_r1816079617
########## c++/src/io/Cache.hh: ########## @@ -0,0 +1,208 @@ +/** + * 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. + */ + +#pragma once + +#include <orc/MemoryPool.hh> +#include <orc/OrcFile.hh> + +#include <algorithm> +#include <cassert> +#include <cstdint> +#include <future> +#include <utility> +#include <vector> + +namespace orc { + class InputStream; + + struct CacheOptions { + /// The maximum distance in bytes between two consecutive + /// ranges; beyond this value, ranges are not combined + uint64_t holeSizeLimit = 8192; + + /// The maximum size in bytes of a combined range; if + /// combining two consecutive ranges would produce a range of a + /// size greater than this, they are not combined + uint64_t rangeSizeLimit = 32 * 1024 * 1024; + }; + + struct ReadRange { + uint64_t offset; + uint64_t length; + + ReadRange() = default; + ReadRange(uint64_t offset, uint64_t length) : offset(offset), length(length) {} + + friend bool operator==(const ReadRange& left, const ReadRange& right) { + return (left.offset == right.offset && left.length == right.length); + } + friend bool operator!=(const ReadRange& left, const ReadRange& right) { + return !(left == right); + } + + bool contains(const ReadRange& other) const { + return (offset <= other.offset && offset + length >= other.offset + other.length); + } + }; + + struct ReadRangeCombiner { + std::vector<ReadRange> coalesce(std::vector<ReadRange> ranges) const { + if (ranges.empty()) { + return ranges; + } + + // Remove zero-sized ranges + auto end = std::remove_if(ranges.begin(), ranges.end(), + [](const ReadRange& range) { return range.length == 0; }); + // Sort in position order + std::sort(ranges.begin(), end, [](const ReadRange& a, const ReadRange& b) { + return a.offset != b.offset ? a.offset < b.offset : a.length > b.length; + }); + + // Remove ranges that overlap 100% + end = std::unique(ranges.begin(), end, [](const ReadRange& left, const ReadRange& right) { + return left.contains(right); + }); + ranges.resize(end - ranges.begin()); + + // Skip further processing if ranges is empty after removing zero-sized ranges. + if (ranges.empty()) { + return ranges; + } + +#ifndef NDEBUG + for (size_t i = 0; i < ranges.size() - 1; ++i) { + const auto& left = ranges[i]; + const auto& right = ranges[i + 1]; + assert(left.offset < right.offset); + assert(!left.contains(right)); + } +#endif + + std::vector<ReadRange> coalesced; + + auto itr = ranges.begin(); + // Ensure ranges is not empty. + assert(itr <= ranges.end()); + // Start of the current coalesced range and end (exclusive) of previous range. + // Both are initialized with the start of first range which is a placeholder value. + uint64_t coalesced_start = itr->offset; + uint64_t prev_range_end = coalesced_start; + + for (; itr < ranges.end(); ++itr) { Review Comment: done. -- This is an automated message from the Apache Git Service. To respond to the message, please log on to GitHub and use the URL above to go to the specific comment. To unsubscribe, e-mail: [email protected] For queries about this service, please contact Infrastructure at: [email protected]
