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/**
* 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 <cassert>
#include "Cache.hh"
namespace orc {
std::vector<ReadRange> ReadRangeCombiner::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%
std::vector<ReadRange> uniqueRanges;
uniqueRanges.reserve(ranges.size());
for (auto it = ranges.begin(); it != end; ++it) {
if (uniqueRanges.empty() || !uniqueRanges.back().contains(*it)) {
uniqueRanges.push_back(*it);
}
}
ranges = std::move(uniqueRanges);
// 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();
// 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 coalescedStart = itr->offset;
uint64_t coalescedEnd = coalescedStart + itr->length;
for (++itr; itr < ranges.end(); ++itr) {
const uint64_t currentRangeStart = itr->offset;
const uint64_t currentRangeEnd = currentRangeStart + itr->length;
assert(coalescedStart < coalescedEnd);
assert(currentRangeStart < currentRangeEnd);
// At this point, the coalesced range is [coalesced_start, prev_range_end).
// Stop coalescing if:
// - coalesced range is too large, or
// - distance (hole/gap) between consecutive ranges is too large.
if ((currentRangeEnd - coalescedStart > rangeSizeLimit) ||
(currentRangeStart > coalescedEnd + holeSizeLimit)) {
coalesced.push_back({coalescedStart, coalescedEnd - coalescedStart});
coalescedStart = currentRangeStart;
}
// Update the prev_range_end with the current range.
coalescedEnd = currentRangeEnd;
}
coalesced.push_back({coalescedStart, coalescedEnd - coalescedStart});
assert(coalesced.front().offset == ranges.front().offset);
assert(coalesced.back().offset + coalesced.back().length ==
ranges.back().offset + ranges.back().length);
return coalesced;
}
std::vector<ReadRange> ReadRangeCombiner::coalesceReadRanges(std::vector<ReadRange> ranges,
uint64_t holeSizeLimit,
uint64_t rangeSizeLimit) {
assert(rangeSizeLimit > holeSizeLimit);
ReadRangeCombiner combiner{holeSizeLimit, rangeSizeLimit};
return combiner.coalesce(std::move(ranges));
}
void ReadRangeCache::cache(std::vector<ReadRange> ranges) {
ranges = ReadRangeCombiner::coalesceReadRanges(std::move(ranges), options_.holeSizeLimit,
options_.rangeSizeLimit);
std::vector<RangeCacheEntry> newEntries = makeCacheEntries(ranges);
// Add new entries, themselves ordered by offset
if (entries_.size() > 0) {
std::vector<RangeCacheEntry> merged(entries_.size() + newEntries.size());
std::merge(entries_.begin(), entries_.end(), newEntries.begin(), newEntries.end(),
merged.begin());
entries_ = std::move(merged);
} else {
entries_ = std::move(newEntries);
}
}
BufferSlice ReadRangeCache::read(const ReadRange& range) {
if (range.length == 0) {
return {std::make_shared<Buffer>(*memoryPool_, 0), 0, 0};
}
const auto it = std::lower_bound(entries_.begin(), entries_.end(), range,
[](const RangeCacheEntry& entry, const ReadRange& range) {
return entry.range.offset + entry.range.length <
range.offset + range.length;
});
BufferSlice result{};
bool hit_cache = false;
if (it != entries_.end() && it->range.contains(range)) {
hit_cache = it->future.valid();
it->future.get();
result = BufferSlice{it->buffer, range.offset - it->range.offset, range.length};
}
if (metrics_) {
if (hit_cache)
metrics_->ReadRangeCacheHits.fetch_add(1);
else
metrics_->ReadRangeCacheMisses.fetch_add(1);
}
return result;
}
void ReadRangeCache::evictEntriesBefore(uint64_t boundary) {
auto it = std::lower_bound(entries_.begin(), entries_.end(), boundary,
[](const RangeCacheEntry& entry, uint64_t offset) {
return entry.range.offset + entry.range.length <= offset;
});
entries_.erase(entries_.begin(), it);
}
std::vector<RangeCacheEntry> ReadRangeCache::makeCacheEntries(
const std::vector<ReadRange>& ranges) const {
std::vector<RangeCacheEntry> newEntries;
newEntries.reserve(ranges.size());
for (const auto& range : ranges) {
BufferPtr buffer = std::make_shared<Buffer>(*memoryPool_, range.length);
std::future<void> future = stream_->readAsync(buffer->data(), buffer->size(), range.offset);
newEntries.emplace_back(range, std::move(buffer), std::move(future));
}
return newEntries;
}
} // namespace orc
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