#ifdef SSD_ROCKSDB_EXPERIMENTAL

#include <rocksdb/cache.h>
#include <rocksdb/db.h>
#include <rocksdb/filter_policy.h>
#include <rocksdb/options.h>
#include <rocksdb/slice_transform.h>
#include <rocksdb/statistics.h>
#include <rocksdb/table.h>
#include <rocksdb/utilities/table_properties_collectors.h>
#include "fdbserver/CoroFlow.h"
#include "flow/flow.h"
#include "flow/IThreadPool.h"
#include "flow/ThreadHelper.actor.h"

#include <memory>
#include <tuple>
#include <vector>

#endif // SSD_ROCKSDB_EXPERIMENTAL

#include "fdbserver/IKeyValueStore.h"
#include "flow/actorcompiler.h" // has to be last include

#ifdef SSD_ROCKSDB_EXPERIMENTAL

namespace {

rocksdb::Slice toSlice(StringRef s) {
	return rocksdb::Slice(reinterpret_cast<const char*>(s.begin()), s.size());
}

StringRef toStringRef(rocksdb::Slice s) {
	return StringRef(reinterpret_cast<const uint8_t*>(s.data()), s.size());
}

rocksdb::ColumnFamilyOptions getCFOptions() {
	rocksdb::ColumnFamilyOptions options;
	options.level_compaction_dynamic_level_bytes = true;
	options.OptimizeLevelStyleCompaction(SERVER_KNOBS->ROCKSDB_MEMTABLE_BYTES);
	if (SERVER_KNOBS->ROCKSDB_PERIODIC_COMPACTION_SECONDS > 0) {
		options.periodic_compaction_seconds = SERVER_KNOBS->ROCKSDB_PERIODIC_COMPACTION_SECONDS;
	}
	// Compact sstables when there's too much deleted stuff.
	options.table_properties_collector_factories = { rocksdb::NewCompactOnDeletionCollectorFactory(128, 1) };
	return options;
}

rocksdb::Options getOptions() {
	rocksdb::Options options({}, getCFOptions());
	options.avoid_unnecessary_blocking_io = true;
	options.create_if_missing = true;
	if (SERVER_KNOBS->ROCKSDB_BACKGROUND_PARALLELISM > 0) {
		options.IncreaseParallelism(SERVER_KNOBS->ROCKSDB_BACKGROUND_PARALLELISM);
	}

	options.statistics = rocksdb::CreateDBStatistics();
	options.statistics->set_stats_level(rocksdb::kExceptHistogramOrTimers);

	rocksdb::BlockBasedTableOptions bbOpts;
	// TODO: Add a knob for the block cache size. (Default is 8 MB)
	if (SERVER_KNOBS->ROCKSDB_PREFIX_LEN > 0) {
		// Prefix blooms are used during Seek.
		options.prefix_extractor.reset(rocksdb::NewFixedPrefixTransform(SERVER_KNOBS->ROCKSDB_PREFIX_LEN));

		// Also turn on bloom filters in the memtable.
		// TODO: Make a knob for this as well.
		options.memtable_prefix_bloom_size_ratio = 0.1;

		// 5 -- Can be read by RocksDB's versions since 6.6.0. Full and partitioned
		// filters use a generally faster and more accurate Bloom filter
		// implementation, with a different schema.
		// https://github.com/facebook/rocksdb/blob/b77569f18bfc77fb1d8a0b3218f6ecf571bc4988/include/rocksdb/table.h#L391
		bbOpts.format_version = 5;

		// Create and apply a bloom filter using the 10 bits
		// which should yield a ~1% false positive rate:
		// https://github.com/facebook/rocksdb/wiki/RocksDB-Bloom-Filter#full-filters-new-format
		bbOpts.filter_policy.reset(rocksdb::NewBloomFilterPolicy(10));

		// The whole key blooms are only used for point lookups.
		// https://github.com/facebook/rocksdb/wiki/RocksDB-Bloom-Filter#prefix-vs-whole-key
		bbOpts.whole_key_filtering = false;
	}

	if (SERVER_KNOBS->ROCKSDB_BLOCK_CACHE_SIZE > 0) {
		bbOpts.block_cache = rocksdb::NewLRUCache(SERVER_KNOBS->ROCKSDB_BLOCK_CACHE_SIZE);
	}

	options.table_factory.reset(rocksdb::NewBlockBasedTableFactory(bbOpts));
	return options;
}

// Set some useful defaults desired for all reads.
rocksdb::ReadOptions getReadOptions() {
	rocksdb::ReadOptions options;
	options.background_purge_on_iterator_cleanup = true;
	return options;
}

ACTOR Future<Void> rocksDBMetricLogger(std::shared_ptr<rocksdb::Statistics> statistics, rocksdb::DB* db) {
	state std::vector<std::tuple<const char*, uint32_t, uint64_t>> tickerStats = {
		{ "StallMicros", rocksdb::STALL_MICROS, 0 },
		{ "BytesRead", rocksdb::BYTES_READ, 0 },
		{ "IterBytesRead", rocksdb::ITER_BYTES_READ, 0 },
		{ "BytesWritten", rocksdb::BYTES_WRITTEN, 0 },
		{ "BlockCacheMisses", rocksdb::BLOCK_CACHE_MISS, 0 },
		{ "BlockCacheHits", rocksdb::BLOCK_CACHE_HIT, 0 },
		{ "BloomFilterUseful", rocksdb::BLOOM_FILTER_USEFUL, 0 },
		{ "BloomFilterFullPositive", rocksdb::BLOOM_FILTER_FULL_POSITIVE, 0 },
		{ "BloomFilterTruePositive", rocksdb::BLOOM_FILTER_FULL_TRUE_POSITIVE, 0 },
		{ "BloomFilterMicros", rocksdb::BLOOM_FILTER_MICROS, 0 },
		{ "MemtableHit", rocksdb::MEMTABLE_HIT, 0 },
		{ "MemtableMiss", rocksdb::MEMTABLE_MISS, 0 },
		{ "GetHitL0", rocksdb::GET_HIT_L0, 0 },
		{ "GetHitL1", rocksdb::GET_HIT_L1, 0 },
		{ "GetHitL2AndUp", rocksdb::GET_HIT_L2_AND_UP, 0 },
		{ "CountKeysWritten", rocksdb::NUMBER_KEYS_WRITTEN, 0 },
		{ "CountKeysRead", rocksdb::NUMBER_KEYS_READ, 0 },
		{ "CountDBSeek", rocksdb::NUMBER_DB_SEEK, 0 },
		{ "CountDBNext", rocksdb::NUMBER_DB_NEXT, 0 },
		{ "CountDBPrev", rocksdb::NUMBER_DB_PREV, 0 },
		{ "BloomFilterPrefixChecked", rocksdb::BLOOM_FILTER_PREFIX_CHECKED, 0 },
		{ "BloomFilterPrefixUseful", rocksdb::BLOOM_FILTER_PREFIX_USEFUL, 0 },
		{ "BlockCacheCompressedMiss", rocksdb::BLOCK_CACHE_COMPRESSED_MISS, 0 },
		{ "BlockCacheCompressedHit", rocksdb::BLOCK_CACHE_COMPRESSED_HIT, 0 },
		{ "CountWalFileSyncs", rocksdb::WAL_FILE_SYNCED, 0 },
		{ "CountWalFileBytes", rocksdb::WAL_FILE_BYTES, 0 },
		{ "CompactReadBytes", rocksdb::COMPACT_READ_BYTES, 0 },
		{ "CompactWriteBytes", rocksdb::COMPACT_WRITE_BYTES, 0 },
		{ "FlushWriteBytes", rocksdb::FLUSH_WRITE_BYTES, 0 },
		{ "CountBlocksCompressed", rocksdb::NUMBER_BLOCK_COMPRESSED, 0 },
		{ "CountBlocksDecompressed", rocksdb::NUMBER_BLOCK_DECOMPRESSED, 0 },
		{ "RowCacheHit", rocksdb::ROW_CACHE_HIT, 0 },
		{ "RowCacheMiss", rocksdb::ROW_CACHE_MISS, 0 },
		{ "CountIterSkippedKeys", rocksdb::NUMBER_ITER_SKIP, 0 },

	};
	state std::vector<std::pair<const char*, std::string>> propertyStats = {
		{ "NumCompactionsRunning", rocksdb::DB::Properties::kNumRunningCompactions },
		{ "NumImmutableMemtables", rocksdb::DB::Properties::kNumImmutableMemTable },
		{ "NumImmutableMemtablesFlushed", rocksdb::DB::Properties::kNumImmutableMemTableFlushed },
		{ "IsMemtableFlushPending", rocksdb::DB::Properties::kMemTableFlushPending },
		{ "NumRunningFlushes", rocksdb::DB::Properties::kNumRunningFlushes },
		{ "IsCompactionPending", rocksdb::DB::Properties::kCompactionPending },
		{ "NumRunningCompactions", rocksdb::DB::Properties::kNumRunningCompactions },
		{ "CumulativeBackgroundErrors", rocksdb::DB::Properties::kBackgroundErrors },
		{ "CurrentSizeActiveMemtable", rocksdb::DB::Properties::kCurSizeActiveMemTable },
		{ "AllMemtablesBytes", rocksdb::DB::Properties::kCurSizeAllMemTables },
		{ "ActiveMemtableBytes", rocksdb::DB::Properties::kSizeAllMemTables },
		{ "CountEntriesActiveMemtable", rocksdb::DB::Properties::kNumEntriesActiveMemTable },
		{ "CountEntriesImmutMemtables", rocksdb::DB::Properties::kNumEntriesImmMemTables },
		{ "CountDeletesActiveMemtable", rocksdb::DB::Properties::kNumDeletesActiveMemTable },
		{ "CountDeletesImmutMemtables", rocksdb::DB::Properties::kNumDeletesImmMemTables },
		{ "EstimatedCountKeys", rocksdb::DB::Properties::kEstimateNumKeys },
		{ "EstimateSstReaderBytes", rocksdb::DB::Properties::kEstimateTableReadersMem },
		{ "CountActiveSnapshots", rocksdb::DB::Properties::kNumSnapshots },
		{ "OldestSnapshotTime", rocksdb::DB::Properties::kOldestSnapshotTime },
		{ "CountLiveVersions", rocksdb::DB::Properties::kNumLiveVersions },
		{ "EstimateLiveDataSize", rocksdb::DB::Properties::kEstimateLiveDataSize },
		{ "BaseLevel", rocksdb::DB::Properties::kBaseLevel },
		{ "EstPendCompactBytes", rocksdb::DB::Properties::kEstimatePendingCompactionBytes },
	};
	loop {
		wait(delay(SERVER_KNOBS->ROCKSDB_METRICS_DELAY));
		TraceEvent e("RocksDBMetrics");
		for (auto& t : tickerStats) {
			auto& [name, ticker, cum] = t;
			uint64_t val = statistics->getTickerCount(ticker);
			e.detail(name, val - cum);
			cum = val;
		}

		for (auto& p : propertyStats) {
			auto& [name, property] = p;
			uint64_t stat = 0;
			ASSERT(db->GetIntProperty(property, &stat));
			e.detail(name, stat);
		}
	}
}

struct RocksDBKeyValueStore : IKeyValueStore {
	using DB = rocksdb::DB*;
	using CF = rocksdb::ColumnFamilyHandle*;

	struct Writer : IThreadPoolReceiver {
		DB& db;
		UID id;

		explicit Writer(DB& db, UID id) : db(db), id(id) {}

		~Writer() override {
			if (db) {
				delete db;
			}
		}

		void init() override {}

		Error statusToError(const rocksdb::Status& s) {
			if (s == rocksdb::Status::IOError()) {
				return io_error();
			} else {
				return unknown_error();
			}
		}

		struct OpenAction : TypedAction<Writer, OpenAction> {
			std::string path;
			ThreadReturnPromise<Void> done;
			Optional<Future<Void>>& metrics;
			OpenAction(std::string path, Optional<Future<Void>>& metrics) : path(std::move(path)), metrics(metrics) {}

			double getTimeEstimate() const override { return SERVER_KNOBS->COMMIT_TIME_ESTIMATE; }
		};
		void action(OpenAction& a) {
			std::vector<rocksdb::ColumnFamilyDescriptor> defaultCF = { rocksdb::ColumnFamilyDescriptor{
				"default", getCFOptions() } };
			std::vector<rocksdb::ColumnFamilyHandle*> handle;
			auto options = getOptions();
			auto status = rocksdb::DB::Open(options, a.path, defaultCF, &handle, &db);
			if (!status.ok()) {
				TraceEvent(SevError, "RocksDBError").detail("Error", status.ToString()).detail("Method", "Open");
				a.done.sendError(statusToError(status));
			} else {
				TraceEvent(SevInfo, "RocksDB").detail("Path", a.path).detail("Method", "Open");
				onMainThread([&] {
					a.metrics = rocksDBMetricLogger(options.statistics, db);
					return Future<bool>(true);
				}).blockUntilReady();
				a.done.send(Void());
			}
		}

		struct DeleteVisitor : public rocksdb::WriteBatch::Handler {
			VectorRef<KeyRangeRef>& deletes;
			Arena& arena;

			DeleteVisitor(VectorRef<KeyRangeRef>& deletes, Arena& arena) : deletes(deletes), arena(arena) {}

			rocksdb::Status DeleteRangeCF(uint32_t /*column_family_id*/,
			                              const rocksdb::Slice& begin,
			                              const rocksdb::Slice& end) override {
				KeyRangeRef kr(toStringRef(begin), toStringRef(end));
				deletes.push_back_deep(arena, kr);
				return rocksdb::Status::OK();
			}
		};

		struct CommitAction : TypedAction<Writer, CommitAction> {
			std::unique_ptr<rocksdb::WriteBatch> batchToCommit;
			ThreadReturnPromise<Void> done;
			double getTimeEstimate() const override { return SERVER_KNOBS->COMMIT_TIME_ESTIMATE; }
		};
		void action(CommitAction& a) {
			Standalone<VectorRef<KeyRangeRef>> deletes;
			DeleteVisitor dv(deletes, deletes.arena());
			ASSERT(a.batchToCommit->Iterate(&dv).ok());
			// If there are any range deletes, we should have added them to be deleted.
			ASSERT(!deletes.empty() || !a.batchToCommit->HasDeleteRange());
			rocksdb::WriteOptions options;
			options.sync = !SERVER_KNOBS->ROCKSDB_UNSAFE_AUTO_FSYNC;
			auto s = db->Write(options, a.batchToCommit.get());
			if (!s.ok()) {
				TraceEvent(SevError, "RocksDBError").detail("Error", s.ToString()).detail("Method", "Commit");
				a.done.sendError(statusToError(s));
			} else {
				a.done.send(Void());
				for (const auto& keyRange : deletes) {
					auto begin = toSlice(keyRange.begin);
					auto end = toSlice(keyRange.end);
					ASSERT(db->SuggestCompactRange(db->DefaultColumnFamily(), &begin, &end).ok());
				}
			}
		}

		struct CloseAction : TypedAction<Writer, CloseAction> {
			ThreadReturnPromise<Void> done;
			std::string path;
			bool deleteOnClose;
			CloseAction(std::string path, bool deleteOnClose) : path(path), deleteOnClose(deleteOnClose) {}
			double getTimeEstimate() const override { return SERVER_KNOBS->COMMIT_TIME_ESTIMATE; }
		};
		void action(CloseAction& a) {
			if (db == nullptr) {
				a.done.send(Void());
				return;
			}
			auto s = db->Close();
			if (!s.ok()) {
				TraceEvent(SevError, "RocksDBError").detail("Error", s.ToString()).detail("Method", "Close");
			}
			if (a.deleteOnClose) {
				std::vector<rocksdb::ColumnFamilyDescriptor> defaultCF = { rocksdb::ColumnFamilyDescriptor{
					"default", getCFOptions() } };
				s = rocksdb::DestroyDB(a.path, getOptions(), defaultCF);
				if (!s.ok()) {
					TraceEvent(SevError, "RocksDBError").detail("Error", s.ToString()).detail("Method", "Destroy");
				} else {
					TraceEvent(SevInfo, "RocksDB").detail("Path", a.path).detail("Method", "Destroy");
				}
			}
			TraceEvent(SevInfo, "RocksDB").detail("Path", a.path).detail("Method", "Close");
			a.done.send(Void());
		}
	};

	struct Reader : IThreadPoolReceiver {
		DB& db;

		explicit Reader(DB& db) : db(db) {}

		void init() override {}

		struct ReadValueAction : TypedAction<Reader, ReadValueAction> {
			Key key;
			Optional<UID> debugID;
			ThreadReturnPromise<Optional<Value>> result;
			ReadValueAction(KeyRef key, Optional<UID> debugID) : key(key), debugID(debugID) {}
			double getTimeEstimate() const override { return SERVER_KNOBS->READ_VALUE_TIME_ESTIMATE; }
		};
		void action(ReadValueAction& a) {
			Optional<TraceBatch> traceBatch;
			if (a.debugID.present()) {
				traceBatch = { TraceBatch{} };
				traceBatch.get().addEvent("GetValueDebug", a.debugID.get().first(), "Reader.Before");
			}
			rocksdb::PinnableSlice value;
			auto s = db->Get(getReadOptions(), db->DefaultColumnFamily(), toSlice(a.key), &value);
			if (a.debugID.present()) {
				traceBatch.get().addEvent("GetValueDebug", a.debugID.get().first(), "Reader.After");
				traceBatch.get().dump();
			}
			if (s.ok()) {
				a.result.send(Value(toStringRef(value)));
			} else {
				if (!s.IsNotFound()) {
					TraceEvent(SevError, "RocksDBError").detail("Error", s.ToString()).detail("Method", "ReadValue");
				}
				a.result.send(Optional<Value>());
			}
		}

		struct ReadValuePrefixAction : TypedAction<Reader, ReadValuePrefixAction> {
			Key key;
			int maxLength;
			Optional<UID> debugID;
			ThreadReturnPromise<Optional<Value>> result;
			ReadValuePrefixAction(Key key, int maxLength, Optional<UID> debugID)
			  : key(key), maxLength(maxLength), debugID(debugID){};
			double getTimeEstimate() const override { return SERVER_KNOBS->READ_VALUE_TIME_ESTIMATE; }
		};
		void action(ReadValuePrefixAction& a) {
			rocksdb::PinnableSlice value;
			Optional<TraceBatch> traceBatch;
			if (a.debugID.present()) {
				traceBatch = { TraceBatch{} };
				traceBatch.get().addEvent("GetValuePrefixDebug",
				                          a.debugID.get().first(),
				                          "Reader.Before"); //.detail("TaskID", g_network->getCurrentTask());
			}
			auto s = db->Get(getReadOptions(), db->DefaultColumnFamily(), toSlice(a.key), &value);
			if (a.debugID.present()) {
				traceBatch.get().addEvent("GetValuePrefixDebug",
				                          a.debugID.get().first(),
				                          "Reader.After"); //.detail("TaskID", g_network->getCurrentTask());
				traceBatch.get().dump();
			}
			if (s.ok()) {
				a.result.send(Value(StringRef(reinterpret_cast<const uint8_t*>(value.data()),
				                              std::min(value.size(), size_t(a.maxLength)))));
			} else {
				if (!s.IsNotFound()) {
					TraceEvent(SevError, "RocksDBError")
					    .detail("Error", s.ToString())
					    .detail("Method", "ReadValuePrefix");
				}
				a.result.send(Optional<Value>());
			}
		}

		struct ReadRangeAction : TypedAction<Reader, ReadRangeAction>, FastAllocated<ReadRangeAction> {
			KeyRange keys;
			int rowLimit, byteLimit;
			ThreadReturnPromise<RangeResult> result;
			ReadRangeAction(KeyRange keys, int rowLimit, int byteLimit)
			  : keys(keys), rowLimit(rowLimit), byteLimit(byteLimit) {}
			double getTimeEstimate() const override { return SERVER_KNOBS->READ_RANGE_TIME_ESTIMATE; }
		};
		void action(ReadRangeAction& a) {
			RangeResult result;
			if (a.rowLimit == 0 || a.byteLimit == 0) {
				a.result.send(result);
			}
			int accumulatedBytes = 0;
			rocksdb::Status s;
			auto options = getReadOptions();
			// When using a prefix extractor, ensure that keys are returned in order even if they cross
			// a prefix boundary.
			options.auto_prefix_mode = (SERVER_KNOBS->ROCKSDB_PREFIX_LEN > 0);
			if (a.rowLimit >= 0) {
				auto endSlice = toSlice(a.keys.end);
				options.iterate_upper_bound = &endSlice;
				auto cursor = std::unique_ptr<rocksdb::Iterator>(db->NewIterator(options));
				cursor->Seek(toSlice(a.keys.begin));
				while (cursor->Valid() && toStringRef(cursor->key()) < a.keys.end) {
					KeyValueRef kv(toStringRef(cursor->key()), toStringRef(cursor->value()));
					accumulatedBytes += sizeof(KeyValueRef) + kv.expectedSize();
					result.push_back_deep(result.arena(), kv);
					// Calling `cursor->Next()` is potentially expensive, so short-circut here just in case.
					if (result.size() >= a.rowLimit || accumulatedBytes >= a.byteLimit) {
						break;
					}
					cursor->Next();
				}
				s = cursor->status();
			} else {
				auto beginSlice = toSlice(a.keys.begin);
				options.iterate_lower_bound = &beginSlice;
				auto cursor = std::unique_ptr<rocksdb::Iterator>(db->NewIterator(options));
				cursor->SeekForPrev(toSlice(a.keys.end));
				if (cursor->Valid() && toStringRef(cursor->key()) == a.keys.end) {
					cursor->Prev();
				}
				while (cursor->Valid() && toStringRef(cursor->key()) >= a.keys.begin) {
					KeyValueRef kv(toStringRef(cursor->key()), toStringRef(cursor->value()));
					accumulatedBytes += sizeof(KeyValueRef) + kv.expectedSize();
					result.push_back_deep(result.arena(), kv);
					// Calling `cursor->Prev()` is potentially expensive, so short-circut here just in case.
					if (result.size() >= -a.rowLimit || accumulatedBytes >= a.byteLimit) {
						break;
					}
					cursor->Prev();
				}
				s = cursor->status();
			}

			if (!s.ok()) {
				TraceEvent(SevError, "RocksDBError").detail("Error", s.ToString()).detail("Method", "ReadRange");
			}
			result.more =
			    (result.size() == a.rowLimit) || (result.size() == -a.rowLimit) || (accumulatedBytes >= a.byteLimit);
			if (result.more) {
				result.readThrough = result[result.size() - 1].key;
			}
			a.result.send(result);
		}
	};

	DB db = nullptr;
	std::string path;
	UID id;
	Reference<IThreadPool> writeThread;
	Reference<IThreadPool> readThreads;
	Promise<Void> errorPromise;
	Promise<Void> closePromise;
	Future<Void> openFuture;
	std::unique_ptr<rocksdb::WriteBatch> writeBatch;
	Optional<Future<Void>> metrics;

	explicit RocksDBKeyValueStore(const std::string& path, UID id) : path(path), id(id) {
		// In simluation, run the reader/writer threads as Coro threads (i.e. in the network thread. The storage engine
		// is still multi-threaded as background compaction threads are still present. Reads/writes to disk will also
		// block the network thread in a way that would be unacceptable in production but is a necessary evil here. When
		// performing the reads in background threads in simulation, the event loop thinks there is no work to do and
		// advances time faster than 1 sec/sec. By the time the blocking read actually finishes, simulation has advanced
		// time by more than 5 seconds, so every read fails with a transaction_too_old error. Doing blocking IO on the
		// main thread solves this issue. There are almost certainly better fixes, but my goal was to get a less
		// invasive change merged first and work on a more realistic version if/when we think that would provide
		// substantially more confidence in the correctness.
		// TODO: Adapt the simulation framework to not advance time quickly when background reads/writes are occurring.
		if (g_network->isSimulated()) {
			writeThread = CoroThreadPool::createThreadPool();
			readThreads = CoroThreadPool::createThreadPool();
		} else {
			writeThread = createGenericThreadPool();
			readThreads = createGenericThreadPool();
		}
		writeThread->addThread(new Writer(db, id), "fdb-rocksdb-wr");
		for (unsigned i = 0; i < SERVER_KNOBS->ROCKSDB_READ_PARALLELISM; ++i) {
			readThreads->addThread(new Reader(db), "fdb-rocksdb-re");
		}
	}

	Future<Void> getError() override { return errorPromise.getFuture(); }

	ACTOR static void doClose(RocksDBKeyValueStore* self, bool deleteOnClose) {
		// The metrics future retains a reference to the DB, so stop it before we delete it.
		self->metrics.reset();

		wait(self->readThreads->stop());
		auto a = new Writer::CloseAction(self->path, deleteOnClose);
		auto f = a->done.getFuture();
		self->writeThread->post(a);
		wait(f);
		wait(self->writeThread->stop());
		if (self->closePromise.canBeSet())
			self->closePromise.send(Void());
		if (self->errorPromise.canBeSet())
			self->errorPromise.send(Never());
		delete self;
	}

	Future<Void> onClosed() override { return closePromise.getFuture(); }

	void dispose() override { doClose(this, true); }

	void close() override { doClose(this, false); }

	KeyValueStoreType getType() const override { return KeyValueStoreType(KeyValueStoreType::SSD_ROCKSDB_V1); }

	Future<Void> init() override {
		if (openFuture.isValid()) {
			return openFuture;
		}
		auto a = std::make_unique<Writer::OpenAction>(path, metrics);
		openFuture = a->done.getFuture();
		writeThread->post(a.release());
		return openFuture;
	}

	void set(KeyValueRef kv, const Arena*) override {
		if (writeBatch == nullptr) {
			writeBatch.reset(new rocksdb::WriteBatch());
		}
		writeBatch->Put(toSlice(kv.key), toSlice(kv.value));
	}

	void clear(KeyRangeRef keyRange, const Arena*) override {
		if (writeBatch == nullptr) {
			writeBatch.reset(new rocksdb::WriteBatch());
		}

		writeBatch->DeleteRange(toSlice(keyRange.begin), toSlice(keyRange.end));
	}

	Future<Void> commit(bool) override {
		// If there is nothing to write, don't write.
		if (writeBatch == nullptr) {
			return Void();
		}
		auto a = new Writer::CommitAction();
		a->batchToCommit = std::move(writeBatch);
		auto res = a->done.getFuture();
		writeThread->post(a);
		return res;
	}

	Future<Optional<Value>> readValue(KeyRef key, Optional<UID> debugID) override {
		auto a = new Reader::ReadValueAction(key, debugID);
		auto res = a->result.getFuture();
		readThreads->post(a);
		return res;
	}

	Future<Optional<Value>> readValuePrefix(KeyRef key, int maxLength, Optional<UID> debugID) override {
		auto a = new Reader::ReadValuePrefixAction(key, maxLength, debugID);
		auto res = a->result.getFuture();
		readThreads->post(a);
		return res;
	}

	Future<RangeResult> readRange(KeyRangeRef keys, int rowLimit, int byteLimit) override {
		auto a = new Reader::ReadRangeAction(keys, rowLimit, byteLimit);
		auto res = a->result.getFuture();
		readThreads->post(a);
		return res;
	}

	StorageBytes getStorageBytes() const override {
		uint64_t live = 0;
		ASSERT(db->GetIntProperty(rocksdb::DB::Properties::kLiveSstFilesSize, &live));

		int64_t free;
		int64_t total;
		g_network->getDiskBytes(path, free, total);

		return StorageBytes(free, total, live, free);
	}
};

} // namespace

#endif // SSD_ROCKSDB_EXPERIMENTAL

IKeyValueStore* keyValueStoreRocksDB(std::string const& path,
                                     UID logID,
                                     KeyValueStoreType storeType,
                                     bool checkChecksums,
                                     bool checkIntegrity) {
#ifdef SSD_ROCKSDB_EXPERIMENTAL
	return new RocksDBKeyValueStore(path, logID);
#else
	TraceEvent(SevError, "RocksDBEngineInitFailure").detail("Reason", "Built without RocksDB");
	ASSERT(false);
	return nullptr;
#endif // SSD_ROCKSDB_EXPERIMENTAL
}

#ifdef SSD_ROCKSDB_EXPERIMENTAL
#include "flow/UnitTest.h"

namespace {

TEST_CASE("noSim/fdbserver/KeyValueStoreRocksDB/Reopen") {
	state const std::string rocksDBTestDir = "rocksdb-kvstore-reopen-test-db";
	platform::eraseDirectoryRecursive(rocksDBTestDir);

	state IKeyValueStore* kvStore = new RocksDBKeyValueStore(rocksDBTestDir, deterministicRandom()->randomUniqueID());
	wait(kvStore->init());

	kvStore->set({ LiteralStringRef("foo"), LiteralStringRef("bar") });
	wait(kvStore->commit(false));

	Optional<Value> val = wait(kvStore->readValue(LiteralStringRef("foo")));
	ASSERT(Optional<Value>(LiteralStringRef("bar")) == val);

	Future<Void> closed = kvStore->onClosed();
	kvStore->close();
	wait(closed);

	kvStore = new RocksDBKeyValueStore(rocksDBTestDir, deterministicRandom()->randomUniqueID());
	wait(kvStore->init());
	// Confirm that `init()` is idempotent.
	wait(kvStore->init());

	Optional<Value> val = wait(kvStore->readValue(LiteralStringRef("foo")));
	ASSERT(Optional<Value>(LiteralStringRef("bar")) == val);

	Future<Void> closed = kvStore->onClosed();
	kvStore->close();
	wait(closed);

	platform::eraseDirectoryRecursive(rocksDBTestDir);
	return Void();
}

} // namespace

#endif // SSD_ROCKSDB_EXPERIMENTAL