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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.
*/
#pragma once
#include "orc/MemoryPool.hh"
#include "orc/OrcFile.hh"
#include <algorithm>
#include <cassert>
#include <cstdint>
#include <future>
#include <utility>
#include <vector>
namespace orc {
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 {
const uint64_t holeSizeLimit;
const uint64_t rangeSizeLimit;
std::vector<ReadRange> coalesce(std::vector<ReadRange> ranges) const;
static std::vector<ReadRange> coalesceReadRanges(std::vector<ReadRange> ranges,
uint64_t holeSizeLimit,
uint64_t rangeSizeLimit);
};
using Buffer = DataBuffer<char>;
using BufferPtr = std::shared_ptr<Buffer>;
struct RangeCacheEntry {
ReadRange range;
BufferPtr buffer;
std::shared_future<void> future; // use shared_future in case of multiple get calls
RangeCacheEntry() = default;
RangeCacheEntry(const ReadRange& range, BufferPtr buffer, std::future<void> future)
: range(range), buffer(std::move(buffer)), future(std::move(future).share()) {}
friend bool operator<(const RangeCacheEntry& left, const RangeCacheEntry& right) {
return left.range.offset < right.range.offset;
}
};
struct BufferSlice {
BufferPtr buffer = nullptr;
uint64_t offset = 0;
uint64_t length = 0;
};
/// A read cache designed to hide IO latencies when reading.
class ReadRangeCache {
public:
/// Construct a read cache with given options
explicit ReadRangeCache(InputStream* stream, CacheOptions options, MemoryPool* memoryPool,
ReaderMetrics* metrics = nullptr)
: stream_(stream),
options_(std::move(options)),
memoryPool_(memoryPool),
metrics_(metrics) {}
~ReadRangeCache() = default;
/// Cache the given ranges in the background.
///
/// The caller must ensure that the ranges do not overlap with each other,
/// nor with previously cached ranges. Otherwise, behaviour will be undefined.
void cache(std::vector<ReadRange> ranges);
/// Read a range previously given to Cache().
BufferSlice read(const ReadRange& range);
/// Evict cache entries with its range before given boundary.
void evictEntriesBefore(uint64_t boundary);
private:
std::vector<RangeCacheEntry> makeCacheEntries(const std::vector<ReadRange>& ranges) const;
InputStream* stream_;
CacheOptions options_;
// Ordered by offset (so as to find a matching region by binary search)
std::vector<RangeCacheEntry> entries_;
MemoryPool* memoryPool_;
ReaderMetrics* metrics_;
};
} // namespace orc
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