private async Task <bool> releaseAsync(IDbConnectionAsync conn, LockInfo lockInfo)
{
var state = lockInfo.AsImmutable();
if (!state.HasLock())
{
return(true); //released already
}
var newLockRef = Math.Max(1, state.LockReference + 1);
using (var command = await DbAccessHelperAsync.CreateDbCommand(conn, RELEASE_LOCK))
{
command.Parameters.Add(new SqlParameter("newLockRef", newLockRef));
command.Parameters.Add(new SqlParameter("resource", state.Resource));
command.Parameters.Add(new SqlParameter("lockReference", state.LockReference));
command.Parameters.Add(new SqlParameter("lockedByPID", _PID));
try
{
await command.ExecuteNonQueryAsync();
lockInfo.Update(null, TimeSpan.Zero, 0, FrozenTimeClock.Instance);
return(true);
}
catch (Exception ex)
{
return(false);
}
}
}
private async Task <LockInfo> acquireLockAsync(IDbConnectionAsync conn, Guid resource, int lockReference, TimeSpan timeout)
{
var lockInfo = LockInfo.Empty(resource);
var newLockRef = Math.Max(1, lockReference + 1);
//only acquires lock if old lock reference number matches, and not locked yet.
using (var command = await DbAccessHelperAsync.CreateDbCommand(conn, ACQUIRE_lOCK_COMMANDS))
{
command.Parameters.Add(new SqlParameter("newLockRef", newLockRef));
command.Parameters.Add(new SqlParameter("timeout", Convert.ToInt64(timeout.TotalMilliseconds)));
command.Parameters.Add(new SqlParameter("lockedByMachine", _machineName));
command.Parameters.Add(new SqlParameter("lockedByPID", _PID));
command.Parameters.Add(new SqlParameter("resource", resource));
command.Parameters.Add(new SqlParameter("lockReference", lockReference));
try
{
var dbLockedTill = (DateTime?)await command.ExecuteScalarAsync();
if (dbLockedTill != null)
{
var clock = _clockProvider.GetClock();
lockInfo.Update(dbLockedTill, timeout, newLockRef, clock);
}
}
catch (Exception ex)
{
ex.LogException();
}
return(lockInfo);
}
}
private async Task <LockReferenceValue> GetLatestReferenceAsync(IDbConnectionAsync conn, Guid resource)
{
using (var command = await DbAccessHelperAsync.CreateDbCommand(conn, SELECT_REFERENCE))
{
command.Parameters.Add(new SqlParameter("resource", resource));
using (var reader = (await command.ExecuteReaderAsync()) as SqlDataReader)
{
if (await reader.ReadAsync())
{
var lockReference = ReadInt(reader, 0);
var lockedTill = ReadDateTime(reader, 1);
var utcNow = ReadDateTime(reader, 2);
return(new LockReferenceValue()
{
LockReference = lockReference,
IsFree = lockReference != null && (lockedTill == null || lockedTill < utcNow)
});
}
else
{
return(new LockReferenceValue()
{
LockReference = null, IsFree = false
});
}
}
}
}
private async Task <bool> insertEntryRecordAsync(IDbConnectionAsync conn, Guid resource)
{
using (var command = await DbAccessHelperAsync.CreateDbCommand(conn, SQL_INSERT))
{
command.Parameters.Add(new SqlParameter("resource", resource));
try
{
return(await command.ExecuteNonQueryAsync() > 0);
}
catch (Exception ex)
{
return(false);
}
}
}
private async Task <bool> renewLockAsync(IDbConnectionAsync conn, TimeSpan renewTimeout, LockInfo lockInfo)
{
var state = lockInfo.AsImmutable();
if (!state.HasLock())
{
return(false);
}
var newLockRef = Math.Max(1, state.LockReference + 1);
using (var command = await DbAccessHelperAsync.CreateDbCommand(conn, RENEW_LOCK_COMMANDS))
{
command.Parameters.Add(new SqlParameter("newLockRef", newLockRef));
command.Parameters.Add(new SqlParameter("resource", state.Resource));
command.Parameters.Add(new SqlParameter("lockReference", state.LockReference));
command.Parameters.Add(new SqlParameter("timeout", Convert.ToInt64(renewTimeout.TotalMilliseconds)));
command.Parameters.Add(new SqlParameter("lockedByPID", _PID));
try
{
var dbLockedTill = (DateTime?)await command.ExecuteScalarAsync();
if (dbLockedTill != null)
{
var clock = _clockProvider.GetClock();
lockInfo.Update(dbLockedTill, renewTimeout, newLockRef, clock);
return(lockInfo.AsImmutable().HasLock());
}
return(false);
}
catch (Exception ex)
{
return(false);
}
}
}