public async Task <QueueItem> EnqueueAsync(QueueDbContext context, string value)
{
var item = new QueueItem()
{
Id = Guid.NewGuid().ToString(), Value = value, State = 0, LastModifyDateTime = DateTime.UtcNow
};
var res = await context.Queue.AddAsync(item);
return(res.Entity);
}
public async Task <QueueItem> DequeueAsync(QueueDbContext context)
{
var now = DateTime.UtcNow;
var limitTime = now - TimeSpan.FromSeconds(5);
var res = await context.Queue
.FromSql("UPDATE \"Queue\" SET \"State\" = 1, \"LastModifyDateTime\" = {0} WHERE \"Id\" = (SELECT \"Id\" FROM \"Queue\" WHERE \"State\" = 0 OR (\"State\" = 1 AND \"LastModifyDateTime\" < {1} ) ORDER BY \"LastModifyDateTime\" FOR UPDATE SKIP LOCKED LIMIT 1) RETURNING *", now, limitTime)
.ToListAsync();
var item = res.FirstOrDefault();
if (item != null)
{
context.Queue.Remove(item);
}
return(item);
}
