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Database KV

FiL provides a Key-Value datastore abstraction. This part of the library is NOT header-only and requires compilation with specific options to enable different backends.

Supported Policies

Currently, the following policies are supported (or planned):

  • RocksDB: Fast and reliable KV engine by Meta.
  • Redis: Persistent KV in-memory database.
  • Couchbase: NoSQL performant database.

These datastores are selected because they can be used in-memory, making them excellent choices for local or small-scale projects.

Basic Usage

The abstraction uses a policy-based design. You instantiate a kv_db with the desired backend policy.

#include <fil/kv_db/key_value_db.hh>
#include <fil/kv_db/kv_rocksdb.hh> // If using RocksDB

// Example with RocksDB policy
// Note: requires WITH_FIL_ROCKSDB CMake option
fil::rocksdb_initializer init;
init.path = "/tmp/testdb";
fil::kv_db<fil::kv_rocksdb_policy> db(init);

// Basic operations
db.set({"key", "value"});
auto values = db.get("key");

// Multi-get
auto kvs = db.multi_get({"key1", "key2"});

// Iteration
db.list("prefix", [](std::string_view key, std::string_view value) {
    std::cout << key << ": " << value << std::endl;
    return true; // continue iteration
});

Transactional Support

Some policies support transactions.

auto tx = db.make_transaction();
tx->set({"key", "value"});
tx->commit();

Compilation Options

To use specific backends, enable them in your CMake configuration:

  • WITH_FIL_ROCKSDB: Enables RocksDB backend.
  • WITH_FIL_REDIS: Enables Redis backend.
  • WITH_FIL_COUCHBASE: Enables Couchbase backend.