Table of Contents

ServiceStack.Redis

OptunaSharp.Storage.ServiceStack.Redis provides ServiceStackJournalRedisBackend in OptunaSharp.Storages.Journal. It uses a ServiceStack IRedisClientsManager and borrows clients for journal commands. This adapter connects an existing ServiceStack-based application to the same journal format as the other Redis adapters.

Install and use

Requires .NET 8 or .NET 10 and a reachable Redis server. The package's dependency notice identifies ServiceStack.Redis as commercially licensed with a request-limited free tier. Review the dependency's applicable terms for your application; OptunaSharp's own license does not replace them.

dotnet add package OptunaSharp.Storage.ServiceStack.Redis

using OptunaSharp;
using OptunaSharp.Storages.Journal;
using ServiceStack.Redis;

using var manager = new RedisManagerPool("localhost:6379");
var backend = new ServiceStackJournalRedisBackend(manager, prefix: "experiments");
var study = Optuna.CreateStudy(
    storage: new JournalStorage(backend),
    studyName: "quadratic", loadIfExists: true);
study.Optimize(trial => Math.Pow(trial.SuggestFloat("x", -10, 10), 2), nTrials: 20);

The application owns the manager. The adapter returns borrowed IRedisClient instances after command use. Disposing the adapter does not dispose an injected manager. Keep the manager alive for the entire study workload.

Constructors and endpoint settings

First arguments Behavior
string url Parse the Redis URL and construct a RedisManagerPool
string url, Action<ServiceStack.Redis.RedisEndpoint> configure Modify the native endpoint before pool creation
ServiceStack.Redis.RedisEndpoint endpoint Construct a pool from the native endpoint
IRedisClientsManager manager Borrow clients from your existing manager

All overloads also accept useCluster = false and prefix = "". redis:// and rediss:// URLs are supported. unix:// throws ValueError because this adapter does not support Unix-domain sockets.

The native endpoint is distinct from OptunaSharp.Storages.Journal.RedisEndpoint, the neutral URL-parser result. Qualify or alias the ServiceStack type if both namespaces are imported:

using OptunaSharp.Storages.Journal;
using ServiceStackEndpoint = ServiceStack.Redis.RedisEndpoint;

var backend = new ServiceStackJournalRedisBackend(
    new ServiceStackEndpoint("localhost", 6379) { Db = 1 },
    prefix: "experiments");

The endpoint and URL paths build a RedisManagerPool whose resolver serves the endpoint object itself, so every pooled client copies its host, port, TLS, database, username, password, client name and connect/send/receive timeouts. A URL's timeouts default to redis-py's 5 seconds. These paths do not expose a manager-configuration callback. Use an injected manager for pool selection, pool sizing, or application-managed connection behavior.

ServiceStack.Redis takes certificate callbacks only process-wide (RedisConfig.CertificateValidationCallback), speaks RESP2 only, authenticates only when a password is set, and turns revocation checking on whenever TLS versions are given. So a URL's ssl_cert_reqs=none, ssl_check_hostname=false, extra certificate authorities, client certificate, ssl_min_version, protocol=3, or a user name without a password raises NotSupportedException. Use the StackExchange or NRedisStack backend for those, or configure ServiceStack yourself. Leave the native endpoint's NamespacePrefix unset and use OptunaSharp's prefix argument to preserve the shared journal keys.

As with the other adapters, the backend is IDisposable. The URL and endpoint convenience constructors create an internal pool that the backend owns, and Dispose() closes it. An injected manager is never disposed by the backend.

Commands, compatibility, and limits

The adapter uses GetValue, SetValue, SetValueIfNotExists, and IncrementValue for the raw journal strings. On standalone Redis, reads and appends use ExecLua with the shared scripts: one request per batch of up to 1,000 records and one per appended record, which also stretches a request-metered licence. Cluster mode allocates the counter and writes the record separately, and reads key by key. Snapshots use native byte Get/Set under {prefix}:snapshot:optunasharp, avoiding ServiceStack typed-object serialization.

useCluster selects that append algorithm; it does not provision a cluster or configure the manager's routing. Read the Redis overview for missing-record waits, prefix isolation, and the difference between interoperable logs and runtime-specific snapshots.

Implementation: ServiceStackJournalRedisBackend. Verification covers pool/endpoint/callback constructors, cross-library bytes, and Python read/write interoperability.

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