Don't double-query recently added datoms

src/NexusMods.MnemonicDB.Abstractions/IConnection.cs

@@ -43,7 +43,7 @@ public interface IConnection
     /// <summary>
     ///     A sequential stream of database revisions.
     /// </summary>
-    public IObservable<Revision> Revisions { get; }
+    public IObservable<IDb> Revisions { get; }
 
     /// <summary>
     /// A service provider that entities can use to resolve their values

src/NexusMods.MnemonicDB.Abstractions/IDb.cs

@@ -24,6 +24,11 @@ public interface IDb : IEquatable<IDb>
     ///     The connection that this database is using for its state.
     /// </summary>
     IConnection Connection { get; }
+
+    /// <summary>
+    ///     The datoms that were added in the most recent transaction (indicated by the basis TxId).
+    /// </summary>
+    IndexSegment RecentlyAdded { get; }
 
     /// <summary>
     /// The snapshot that this database is based on.

src/NexusMods.MnemonicDB.Abstractions/Query/ObservableDatoms.cs

@@ -44,19 +44,19 @@ public static IObservable<IChangeSet<Datom>> ObserveDatoms(this IConnection conn
         var lastTxId = TxId.From(0);
 
         return conn.Revisions
-            .Where(rev => rev.AddedDatoms.Valid)
+            .Where(rev => rev.RecentlyAdded.Count > 0)
             .Select((rev, idx) =>
         {
             lock (set)
             {
-                if (rev.Database.BasisTxId <= lastTxId)
+                if (rev.BasisTxId <= lastTxId)
                     return ChangeSet<Datom>.Empty;
 
-                lastTxId = rev.Database.BasisTxId;
+                lastTxId = rev.BasisTxId;
 
                 if (idx == 0)
-                    return Setup(set, rev.Database, descriptor);
-                return Diff(conn.Registry, set, rev.AddedDatoms, descriptor, equality);
+                    return Setup(set, rev, descriptor);
+                return Diff(conn.Registry, set, rev.RecentlyAdded, descriptor, equality);
             }
         });
     }

src/NexusMods.MnemonicDB/Connection.cs

@@ -25,7 +25,7 @@ public class Connection : IConnection
     private readonly Dictionary<Symbol, IAttribute> _declaredAttributes;
     private readonly ILogger<Connection> _logger;
 
-    private BehaviorSubject<Revision> _dbStream;
+    private BehaviorSubject<IDb> _dbStream;
     private IDisposable? _dbStreamDisposable;
 
     /// <summary>
@@ -37,7 +37,7 @@ public Connection(ILogger<Connection> logger, IDatomStore store, IServiceProvide
         _logger = logger;
         _declaredAttributes = declaredAttributes.ToDictionary(a => a.Id);
         _store = store;
-        _dbStream = new BehaviorSubject<Revision>(default!);
+        _dbStream = new BehaviorSubject<IDb>(default!);
         Bootstrap();
     }
 
@@ -73,7 +73,7 @@ public IDb Db
             // ReSharper disable once ConditionIsAlwaysTrueOrFalseAccordingToNullableAPIContract
             if (val == null)
                 ThrowNullDb();
-            return val!.Value.Database;
+            return val!.Value;
         }
     }
 
@@ -106,7 +106,7 @@ public ITransaction BeginTransaction()
     }
 
     /// <inheritdoc />
-    public IObservable<Revision> Revisions
+    public IObservable<IDb> Revisions
     {
         get
         {
@@ -178,13 +178,8 @@ private void Bootstrap()
             _dbStreamDisposable = ForwardOnly(_store.TxLog)
                 .Select(db =>
                 {
-                    db.Connection = this;
-                    var addedItems = db.Datoms(SliceDescriptor.Create(db.BasisTxId, _store.Registry));
-                    return new Revision
-                    {
-                        Database = db,
-                        AddedDatoms = addedItems
-                    };
+                    db.Connection = this; 
+                    return db;
                 })
                 .Subscribe(_dbStream);
         }

src/NexusMods.MnemonicDB/Db.cs

@@ -29,7 +29,7 @@ internal class Db : IDb
     public ISnapshot Snapshot { get; }
     public IAttributeRegistry Registry => _registry;
 
-    public IndexSegment RecentlyAdded;
+    public IndexSegment RecentlyAdded { get; }
 
     public Db(ISnapshot snapshot, TxId txId, AttributeRegistry registry)
     {

tests/NexusMods.MnemonicDB.Storage.Tests/NullConnection.cs

@@ -8,7 +8,7 @@ public class NullConnection : IConnection
     public IDb Db => throw new NotSupportedException();
     public IAttributeRegistry Registry => throw new NotSupportedException();
     public TxId TxId => throw new NotSupportedException();
-    public IObservable<Revision> Revisions => throw new NotSupportedException();
+    public IObservable<IDb> Revisions => throw new NotSupportedException();
     public IServiceProvider ServiceProvider => throw new NotSupportedException();
     public IDb AsOf(TxId txId)
     {

tests/NexusMods.MnemonicDB.Tests/DbTests.cs

@@ -204,8 +204,8 @@ public async Task CanGetCommitUpdates()
         Connection.Revisions.Subscribe(update =>
         {
             // Only Txes we care about
-            if (update.AddedDatoms.Any(d => d.E == realId))
-                updates.Add(update.AddedDatoms.Select(d => d.Resolved).ToArray());
+            if (update.RecentlyAdded.Any(d => d.E == realId))
+                updates.Add(update.RecentlyAdded.Select(d => d.Resolved).ToArray());
         });
 
         for (var idx = 0; idx < 4; idx++)