protected override async Task<Lease> AcquireLease()
{
using (var connection = new SqlConnection(settings.ConnectionString))
{
await connection.OpenAsync();
var cmd = connection.CreateCommand();
cmd.CommandType = CommandType.StoredProcedure;
cmd.CommandText = @"Alluvial.AcquireLease";
cmd.Parameters.AddWithValue(@"@waitIntervalMilliseconds", waitInterval.TotalMilliseconds);
cmd.Parameters.AddWithValue(@"@leaseDurationMilliseconds", defaultLeaseDuration.TotalMilliseconds);
cmd.Parameters.AddWithValue(@"@scope", scope);
using (var reader = await cmd.ExecuteReaderAsync())
{
while (await reader.ReadAsync())
{
var resourceName = await reader.GetFieldValueAsync<string>(0);
var leaseLastGranted = await reader.GetFieldValueAsync<dynamic>(2);
var leaseLastReleased = await reader.GetFieldValueAsync<dynamic>(3);
var token = await reader.GetFieldValueAsync<dynamic>(5);
var resource = new LeasableResource(
resourceName,
defaultLeaseDuration)
{
LeaseLastGranted = leaseLastGranted is DBNull
? DateTimeOffset.MinValue
: (DateTimeOffset) leaseLastGranted,
LeaseLastReleased = leaseLastReleased is DBNull
? DateTimeOffset.MinValue
: (DateTimeOffset) leaseLastReleased
};
Lease lease = null;
lease = new Lease(resource,
resource.DefaultLeaseDuration,
(int) token,
extend: by => ExtendLease(lease, @by));
return lease;
}
}
return null;
}
}
public SqlBrokeredStreamQueryDistributor(
LeasableResource[] leasableResources,
SqlBrokeredStreamQueryDistributorDatabase settings,
string scope,
int maxDegreesOfParallelism = 5,
TimeSpan? waitInterval = null,
TimeSpan? defaultLeaseDuration = null)
: base(leasableResources, maxDegreesOfParallelism, waitInterval)
{
if (settings == null)
{
throw new ArgumentNullException("settings");
}
if (scope == null)
{
throw new ArgumentNullException("scope");
}
this.settings = settings;
this.scope = scope;
this.defaultLeaseDuration = defaultLeaseDuration ?? TimeSpan.FromMinutes(5);
}
