V5 beta fail to serialize double on ARM CPU

Hi, I observe the following error in logs of my app:

System.DataMisalignedException: A datatype misalignment was detected in a load or store instruction.
   at LiteDB.BufferExtensions.ToBytes(Double value, Byte[] array, Int32 startIndex)
   at LiteDB.Engine.BufferWriter.WriteNumber[T](T value, Action`3 toBytes, Int32 size)
   at LiteDB.Engine.BufferWriter.Write(Double value)
   at LiteDB.Engine.BufferWriter.WriteElement(String key, BsonValue value)
   at LiteDB.Engine.BufferWriter.WriteDocument(BsonDocument value, Boolean recalc)
   at LiteDB.Engine.DataService.Insert(BsonDocument doc)
   at LiteDB.Engine.LiteEngine.InsertDocument(Snapshot snapshot, BsonDocument doc, BsonAutoId autoId, IndexService indexer, DataService data)
   at LiteDB.Engine.LiteEngine.<>c__DisplayClass8_0.<Insert>b__0(TransactionService transaction)
   at LiteDB.Engine.LiteEngine.AutoTransaction[T](Func`2 fn)
   at LiteDB.Engine.LiteEngine.Insert(String collection, IEnumerable`1 docs, BsonAutoId autoId)
   at LiteDB.LiteCollection`1.Insert(T document)

It happens everytime on types with non default double values. Here’s the definition of the type:

public class Checkpoint : ICheckpoint
    {
        private static long nextSequence;
        public DateTime Timestamp { get; set; } = new DateTime(0, DateTimeKind.Utc);
        public string RiderId { get; set; }
        public long Id { get; set; }
        
        public DateTime LastSeen { get; set; } = new DateTime(0, DateTimeKind.Utc);
        public int Count { get; set; } = 1;
        public bool Aggregated { get; set; }
        public bool IsManual { get; set; }
        public double Rps { get; set; }

        public Checkpoint()
        {
        }

        public Checkpoint(string riderId, DateTime? timestamp = null)
        {
            Id = Interlocked.Increment(ref nextSequence);
            RiderId = riderId;
            LastSeen = Timestamp = timestamp ?? new DateTime(0, DateTimeKind.Utc);
        }

        public override string ToString()
        {
            return $"{RiderId} Ts:{Timestamp:t}";
        }
        
        private sealed class TimestampRelationalComparer : IComparer<Checkpoint>
        {
            public int Compare(Checkpoint x, Checkpoint y)
            {
                if (ReferenceEquals(x, y)) return 0;
                if (ReferenceEquals(null, y)) return 1;
                if (ReferenceEquals(null, x)) return -1;
                return x.Timestamp.CompareTo(y.Timestamp);
            }
        }
        
        public static IComparer<Checkpoint> TimestampComparer { get; } = new TimestampRelationalComparer();
    }

If the Rps value is zero, the object would serialize and deserialize without problems. Unfortunately, I can’t create a minimal reproduction yet. A simple to save and load one item is not failing. So probably particular value makes the difference

[maxbl4]

Hi, confirm, that build from latest master has fixed the bug. Thanks!

[knippers]

I had the same issue on an old raspberry pi. I compiled the source from master and linked that to my project. Upgrade of an 188MB databse went fine and app is running again. So it seems the issue is indeed closed. Thanks for the fix.