public async Task <T> Query <T>(ISingleQueryHandler <T> handler, CancellationToken cancellation)
{
using var conn = _database.CreateConnection();
var command = handler.BuildCommand();
command.Connection = conn;
await conn.OpenAsync(cancellation).ConfigureAwait(false);
using var reader = await command.ExecuteReaderAsync(cancellation).ConfigureAwait(false);
try
{
return(await handler.HandleAsync(reader, cancellation).ConfigureAwait(false));
}
finally
{
#if NET6_0_OR_GREATER
await reader.CloseAsync().ConfigureAwait(false);
#else
#pragma warning disable VSTHRD103
reader.Close();
#pragma warning restore VSTHRD103
#endif
await conn.CloseAsync().ConfigureAwait(false);
}
}
public async Task <T> Query <T>(ISingleQueryHandler <T> handler, CancellationToken cancellation)
{
using var conn = _database.CreateConnection();
var command = handler.BuildCommand();
command.Connection = conn;
await conn.OpenAsync(cancellation).ConfigureAwait(false);
using var reader = await command.ExecuteReaderAsync(cancellation).ConfigureAwait(false);
return(await handler.HandleAsync(reader, cancellation).ConfigureAwait(false));
}
public async Task SetFloor(long floor)
{
var numberOfPages = (long)Math.Ceiling((double)floor / MaxLo);
var updateSql =
$"update {_options.DatabaseSchemaName}.mt_hilo set hi_value = :floor where entity_name = :name";
// This guarantees that the hilo row exists
await AdvanceToNextHi().ConfigureAwait(false);
using var conn = _database.CreateConnection();
await conn.OpenAsync().ConfigureAwait(false);
await conn.CreateCommand(updateSql)
.With("floor", numberOfPages)
.With("name", _entityName)
.ExecuteNonQueryAsync().ConfigureAwait(false);
// And again to get it where we need it to be
await AdvanceToNextHi().ConfigureAwait(false);
}
private async Task <bool> tryToAttainLockAndStartShards()
{
bool gotLock = false;
NpgsqlConnection conn = null;
try
{
conn = _database.CreateConnection();
await conn.OpenAsync(_cancellation.Token).ConfigureAwait(false);
gotLock = (bool)await conn.CreateCommand("SELECT pg_try_advisory_lock(:id);")
.With("id", _settings.DaemonLockId)
.ExecuteScalarAsync(_cancellation.Token).ConfigureAwait(false);
if (!gotLock)
{
await conn.CloseAsync().ConfigureAwait(false);
}
}
catch (Exception e)
{
conn?.SafeDispose();
_logger.LogError(e, "Error trying to attain the async daemon lock for database {Database}", _database.Identifier);
return(false);
}
if (gotLock)
{
_logger.LogInformation("Attained lock for the async daemon for database {Database}, attempting to start all shards", _database.Identifier);
try
{
await startAllProjections(conn).ConfigureAwait(false);
stopPollingForOwnership();
return(true);
}
catch (Exception ex)
{
_logger.LogError(ex, "Failure while trying to start all async projection shards for database {Database}", _database.Identifier);
}
}
else
{
_logger.LogDebug("Attempted to attain lock for async projections, but could not take leadership for database {Database}.", _database.Identifier);
}
if (_timer == null || !_timer.Enabled)
{
startPollingForOwnership();
}
else
{
_timer.Start();
}
return(false);
}
