Postgres over the ring

ioxide.pg is a hand-rolled Postgres driver where everything - TCP connect, startup handshake, every query - is an io_uring op on the host reactor's ring, resumed inline. No Npgsql, no socket engine, no thread pool.

The pool

var options = new PgOptions
{
    Host = "127.0.0.1",      // IPv4 literal - resolve DNS up front
    User = "bench",
    Database = "bench",
    PoolSize = 8,            // connections per reactor
};

// At startup, on the reactor thread.
reactor.OnStart = r => PgPool.Start(r, options);

// In the handler: rent → query → return, in one call.
var pool   = reactor.GetService<PgPool>();
var result = await pool.QueryAsync("SELECT 42");

// result.Value: "42" · result.Rows: 1 · result.CommandTag: "SELECT 1"

One PgConnection is one conversation - one query in flight. The pool is the concurrency: QueryAsync rents a connection, runs the query, returns it; when all are busy, requests queue and resume inline as connections free up. For multi-statement work (transactions), RentAsync/Return directly.

Warmup is concurrent and non-blocking: Start fires PoolSize ring-native connects; a request that arrives first simply waits in the rent queue until the first connection lands. Total server-side connections = PoolSize × ReactorCount.

Failure semantics

Failure	Behavior
Server error (bad SQL, missing table)	`PgException` with severity + SQLSTATE, thrown after the stream resyncs at ReadyForQuery - the connection stays usable
Transport failure (reset, EOF, malformed framing)	connection marked `IsBroken`; the pool discards it on return and opens a replacement in the background
Database restart	broken connections get replaced as they're returned - the server heals without a restart

try
{
    var result = await pool.QueryAsync(sql);
}
catch (PgException e) when (e.SqlState == "42P01")
{
    // Relation does not exist - the connection is already back in rotation.
}

Wire details

Simple query protocol, UTF-8 throughout; the parser walks messages incrementally and compacts/grows its native buffer (64KB → 1MB) for large responses.
PgResult carries the first column of the first row as text, the row count, and the command tag - enough for the common case; a typed row reader is roadmap.
Trust authentication only, today. SCRAM, the extended protocol (prepared statements), and pipelining are the driver's roadmap, in that order.

Parallel requests overlap their queries across the pool instead of serializing on one connection - see it directly with the Playground's /sleep route and a few concurrent curls.

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