/// <summary>
/// Method to check if a DCRGraph in the database is locked. This is a helper method which is used by all methods which change data in the database.
/// </summary>
/// <param name="guid"></param>
/// <param name="graphId"></param>
/// <param name="db"></param>
/// <returns></returns>
public async Task<Tuple<bool, string>> CheckLock(Guid guid, int graphId, DBO.Database db)
{
var graph = await db.DCRGraphs.FindAsync(graphId);
if (graph == null) return new Tuple<bool, string>(false, "The graph did not exist");
if (graph.Lock == false)
return new Tuple<bool, string>(false, "The graph was not locked when reaching the check lock phase");
if (graph.Guid != guid)
return new Tuple<bool, string>(false, "someone else has locked the graph.");
return new Tuple<bool, string>(true, "");
}
/// <summary>
/// Method to unlock a DCRGraph in the database. This is a helper method which is used by all methods which change data in the database.
/// </summary>
/// <param name="guid"></param>
/// <param name="graphId"></param>
/// <param name="db"></param>
/// <returns></returns>
public async Task<Tuple<bool, string>> Unlock(Guid guid, int graphId, DBO.Database db)
{
var graph = await db.DCRGraphs.FindAsync(graphId);
if (graph == null) return new Tuple<bool, string>(false, "The graph did not exist");
if (graph.Lock == false)
return new Tuple<bool, string>(false, "The graph was not locked when reaching the unlock phase");
if (graph.Guid != guid)
return new Tuple<bool, string>(false, "someone else has locked the graph. Should not be possible.");
//unlock and save to db.
graph.Lock = false;
db.Entry(graph).State = EntityState.Modified;
await db.SaveChangesAsync();
return new Tuple<bool, string>(true, "");
}
/// <summary>
/// Method to lock a DCRGraph in the database. This is a helper method which is used by all methods which change data in the database.
/// </summary>
/// <param name="guid"></param>
/// <param name="graphId"></param>
/// <param name="db"></param>
/// <returns></returns>
public async Task<Tuple<bool, string>> LockGraph(Guid guid, int graphId, DBO.Database db)
{
var graph = await db.DCRGraphs.FindAsync(graphId);
//check if the graph exist
if(graph == null) return new Tuple<bool, string>(false,"The graph did not exist");
//Check that the graph is not locked, and if it is, check whether it's an old lock. Locks older than 1minute we do no care about.
if(graph.Lock && DateTime.Now.Subtract(graph.LockTime).Minutes < 1 ) return new Tuple<bool, string>(false, "The graph is already locked");
//lock this
graph.Lock = true;
graph.LockTime = DateTime.Now;
graph.Guid = guid;
db.Entry(graph).State = EntityState.Modified;
await db.SaveChangesAsync();
return new Tuple<bool, string>(true, "");
}
