Revision fdf403f5918a2b4355cf75ebe5e21d0fc22db880 authored by Andrew Kryczka on 19 February 2023, 21:44:55 UTC, committed by Andrew Kryczka on 19 February 2023, 21:44:55 UTC
1 parent 4b87e21
expected_state.h
// Copyright (c) 2021-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).
#ifdef GFLAGS
#pragma once
#include <stdint.h>
#include <atomic>
#include <memory>
#include "db/dbformat.h"
#include "file/file_util.h"
#include "rocksdb/db.h"
#include "rocksdb/env.h"
#include "rocksdb/file_system.h"
#include "rocksdb/rocksdb_namespace.h"
#include "rocksdb/types.h"
#include "util/string_util.h"
namespace ROCKSDB_NAMESPACE {
// An `ExpectedState` provides read/write access to expected values for every
// key.
class ExpectedState {
public:
explicit ExpectedState(size_t max_key, size_t num_column_families);
virtual ~ExpectedState() {}
// Requires external locking preventing concurrent execution with any other
// member function.
virtual Status Open(bool create) = 0;
// Requires external locking covering all keys in `cf`.
void ClearColumnFamily(int cf);
// @param pending True if the update may have started but is not yet
// guaranteed finished. This is useful for crash-recovery testing when the
// process may crash before updating the expected values array.
//
// Requires external locking covering `key` in `cf`.
void Put(int cf, int64_t key, uint32_t value_base, bool pending);
// Requires external locking covering `key` in `cf`.
uint32_t Get(int cf, int64_t key) const;
// @param pending See comment above Put()
// Returns true if the key was not yet deleted.
//
// Requires external locking covering `key` in `cf`.
bool Delete(int cf, int64_t key, bool pending);
// @param pending See comment above Put()
// Returns true if the key was not yet deleted.
//
// Requires external locking covering `key` in `cf`.
bool SingleDelete(int cf, int64_t key, bool pending);
// @param pending See comment above Put()
// Returns number of keys deleted by the call.
//
// Requires external locking covering keys in `[begin_key, end_key)` in `cf`.
int DeleteRange(int cf, int64_t begin_key, int64_t end_key, bool pending);
// Requires external locking covering `key` in `cf`.
bool Exists(int cf, int64_t key);
private:
// Requires external locking covering `key` in `cf`.
std::atomic<uint32_t>& Value(int cf, int64_t key) const {
return values_[cf * max_key_ + key];
}
const size_t max_key_;
const size_t num_column_families_;
protected:
size_t GetValuesLen() const {
return sizeof(std::atomic<uint32_t>) * num_column_families_ * max_key_;
}
// Requires external locking preventing concurrent execution with any other
// member function.
void Reset();
std::atomic<uint32_t>* values_;
};
// A `FileExpectedState` implements `ExpectedState` backed by a file.
class FileExpectedState : public ExpectedState {
public:
explicit FileExpectedState(std::string expected_state_file_path,
size_t max_key, size_t num_column_families);
// Requires external locking preventing concurrent execution with any other
// member function.
Status Open(bool create) override;
private:
const std::string expected_state_file_path_;
std::unique_ptr<MemoryMappedFileBuffer> expected_state_mmap_buffer_;
};
// An `AnonExpectedState` implements `ExpectedState` backed by a memory
// allocation.
class AnonExpectedState : public ExpectedState {
public:
explicit AnonExpectedState(size_t max_key, size_t num_column_families);
// Requires external locking preventing concurrent execution with any other
// member function.
Status Open(bool create) override;
private:
std::unique_ptr<std::atomic<uint32_t>[]> values_allocation_;
};
// An `ExpectedStateManager` manages data about the expected state of the
// database. It exposes operations for reading and modifying the latest
// expected state.
class ExpectedStateManager {
public:
explicit ExpectedStateManager(size_t max_key, size_t num_column_families);
virtual ~ExpectedStateManager();
// Requires external locking preventing concurrent execution with any other
// member function.
virtual Status Open() = 0;
// Saves expected values for the current state of `db` and begins tracking
// changes. Following a successful `SaveAtAndAfter()`, `Restore()` can be
// called on the same DB, as long as its state does not roll back to before
// its current state.
//
// Requires external locking preventing concurrent execution with any other
// member function. Furthermore, `db` must not be mutated while this function
// is executing.
virtual Status SaveAtAndAfter(DB* db) = 0;
// Returns true if at least one state of historical expected values can be
// restored.
//
// Requires external locking preventing concurrent execution with any other
// member function.
virtual bool HasHistory() = 0;
// Restores expected values according to the current state of `db`. See
// `SaveAtAndAfter()` for conditions where this can be called.
//
// Requires external locking preventing concurrent execution with any other
// member function. Furthermore, `db` must not be mutated while this function
// is executing.
virtual Status Restore(DB* db) = 0;
// Requires external locking covering all keys in `cf`.
void ClearColumnFamily(int cf) { return latest_->ClearColumnFamily(cf); }
// @param pending True if the update may have started but is not yet
// guaranteed finished. This is useful for crash-recovery testing when the
// process may crash before updating the expected values array.
//
// Requires external locking covering `key` in `cf`.
void Put(int cf, int64_t key, uint32_t value_base, bool pending) {
return latest_->Put(cf, key, value_base, pending);
}
// Requires external locking covering `key` in `cf`.
uint32_t Get(int cf, int64_t key) const { return latest_->Get(cf, key); }
// @param pending See comment above Put()
// Returns true if the key was not yet deleted.
//
// Requires external locking covering `key` in `cf`.
bool Delete(int cf, int64_t key, bool pending) {
return latest_->Delete(cf, key, pending);
}
// @param pending See comment above Put()
// Returns true if the key was not yet deleted.
//
// Requires external locking covering `key` in `cf`.
bool SingleDelete(int cf, int64_t key, bool pending) {
return latest_->SingleDelete(cf, key, pending);
}
// @param pending See comment above Put()
// Returns number of keys deleted by the call.
//
// Requires external locking covering keys in `[begin_key, end_key)` in `cf`.
int DeleteRange(int cf, int64_t begin_key, int64_t end_key, bool pending) {
return latest_->DeleteRange(cf, begin_key, end_key, pending);
}
// Requires external locking covering `key` in `cf`.
bool Exists(int cf, int64_t key) { return latest_->Exists(cf, key); }
protected:
const size_t max_key_;
const size_t num_column_families_;
std::unique_ptr<ExpectedState> latest_;
};
// A `FileExpectedStateManager` implements an `ExpectedStateManager` backed by
// a directory of files containing data about the expected state of the
// database.
class FileExpectedStateManager : public ExpectedStateManager {
public:
explicit FileExpectedStateManager(size_t max_key, size_t num_column_families,
std::string expected_state_dir_path);
// Requires external locking preventing concurrent execution with any other
// member function.
Status Open() override;
// See `ExpectedStateManager::SaveAtAndAfter()` API doc.
//
// This implementation makes a copy of "LATEST.state" into
// "<current seqno>.state", and starts a trace in "<current seqno>.trace".
// Due to using external files, a following `Restore()` can happen even
// from a different process.
Status SaveAtAndAfter(DB* db) override;
// See `ExpectedStateManager::HasHistory()` API doc.
bool HasHistory() override;
// See `ExpectedStateManager::Restore()` API doc.
//
// Say `db->GetLatestSequenceNumber()` was `a` last time `SaveAtAndAfter()`
// was called and now it is `b`. Then this function replays `b - a` write
// operations from "`a`.trace" onto "`a`.state", and then copies the resulting
// file into "LATEST.state".
Status Restore(DB* db) override;
private:
// Requires external locking preventing concurrent execution with any other
// member function.
Status Clean();
std::string GetTempPathForFilename(const std::string& filename);
std::string GetPathForFilename(const std::string& filename);
static const std::string kLatestBasename;
static const std::string kStateFilenameSuffix;
static const std::string kTraceFilenameSuffix;
static const std::string kTempFilenamePrefix;
static const std::string kTempFilenameSuffix;
const std::string expected_state_dir_path_;
SequenceNumber saved_seqno_ = kMaxSequenceNumber;
};
// An `AnonExpectedStateManager` implements an `ExpectedStateManager` backed by
// a memory allocation containing data about the expected state of the database.
class AnonExpectedStateManager : public ExpectedStateManager {
public:
explicit AnonExpectedStateManager(size_t max_key, size_t num_column_families);
// See `ExpectedStateManager::SaveAtAndAfter()` API doc.
//
// This implementation returns `Status::NotSupported` since we do not
// currently have a need to keep history of expected state within a process.
Status SaveAtAndAfter(DB* /* db */) override {
return Status::NotSupported();
}
// See `ExpectedStateManager::HasHistory()` API doc.
bool HasHistory() override { return false; }
// See `ExpectedStateManager::Restore()` API doc.
//
// This implementation returns `Status::NotSupported` since we do not
// currently have a need to keep history of expected state within a process.
Status Restore(DB* /* db */) override { return Status::NotSupported(); }
// Requires external locking preventing concurrent execution with any other
// member function.
Status Open() override;
};
} // namespace ROCKSDB_NAMESPACE
#endif // GFLAGS
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