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rust-rocksdb/db/blob/blob_garbage_meter.h

103 lines
2.9 KiB

// Copyright (c) 2011-present, Facebook, Inc. All rights reserved.
// This source code is licensed under both the GPLv2 (found in the
// COPYING file in the root directory) and Apache 2.0 License
// (found in the LICENSE.Apache file in the root directory).
#pragma once
#include <cassert>
#include <cstdint>
#include <unordered_map>
#include "db/blob/blob_constants.h"
#include "rocksdb/rocksdb_namespace.h"
#include "rocksdb/status.h"
namespace ROCKSDB_NAMESPACE {
class Slice;
// A class that can be used to compute the amount of additional garbage
// generated by a compaction. It parses the keys and blob references in the
// input and output of a compaction, and aggregates the "inflow" and "outflow"
// on a per-blob file basis. The amount of additional garbage for any given blob
// file can then be computed by subtracting the outflow from the inflow.
class BlobGarbageMeter {
public:
// A class to store the number and total size of blobs on a per-blob file
// basis.
class BlobStats {
public:
void Add(uint64_t bytes) {
++count_;
bytes_ += bytes;
}
void Add(uint64_t count, uint64_t bytes) {
count_ += count;
bytes_ += bytes;
}
uint64_t GetCount() const { return count_; }
uint64_t GetBytes() const { return bytes_; }
private:
uint64_t count_ = 0;
uint64_t bytes_ = 0;
};
// A class to keep track of the "inflow" and the "outflow" and to compute the
// amount of additional garbage for a given blob file.
class BlobInOutFlow {
public:
void AddInFlow(uint64_t bytes) {
in_flow_.Add(bytes);
assert(IsValid());
}
void AddOutFlow(uint64_t bytes) {
out_flow_.Add(bytes);
assert(IsValid());
}
const BlobStats& GetInFlow() const { return in_flow_; }
const BlobStats& GetOutFlow() const { return out_flow_; }
bool IsValid() const {
return in_flow_.GetCount() >= out_flow_.GetCount() &&
in_flow_.GetBytes() >= out_flow_.GetBytes();
}
bool HasGarbage() const {
assert(IsValid());
return in_flow_.GetCount() > out_flow_.GetCount();
}
uint64_t GetGarbageCount() const {
assert(IsValid());
assert(HasGarbage());
return in_flow_.GetCount() - out_flow_.GetCount();
}
uint64_t GetGarbageBytes() const {
assert(IsValid());
assert(HasGarbage());
return in_flow_.GetBytes() - out_flow_.GetBytes();
}
private:
BlobStats in_flow_;
BlobStats out_flow_;
};
Status ProcessInFlow(const Slice& key, const Slice& value);
Status ProcessOutFlow(const Slice& key, const Slice& value);
const std::unordered_map<uint64_t, BlobInOutFlow>& flows() const {
return flows_;
}
private:
static Status Parse(const Slice& key, const Slice& value,
uint64_t* blob_file_number, uint64_t* bytes);
std::unordered_map<uint64_t, BlobInOutFlow> flows_;
};
} // namespace ROCKSDB_NAMESPACE