Estimated row count hint (DapperLib#31)

* stab at estimate row count

* intermediate

* nearly there

* fix member-name output

* fixup build output

src/Dapper.AOT.Analyzers/AnalyzerReleases.Unshipped.md

@@ -34,6 +34,10 @@ DAP025 | Sql | Warning | Diagnostics
 DAP026 | Sql | Error | Diagnostics
 DAP027 | Performance | Warning | Diagnostics
 DAP028 | Performance | Warning | Diagnostics
+DAP029 | Library | Info | Diagnostics
+DAP030 | Library | Error | Diagnostics
+DAP031 | Library | Error | Diagnostics
+DAP032 | Library | Error | Diagnostics
 DAP100 | Library | Error | Diagnostics
 DAP101 | Library | Error | Diagnostics
 DAP102 | Library | Error | Diagnostics

src/Dapper.AOT.Analyzers/CodeAnalysis/DapperInterceptorGenerator.Multi.cs

@@ -42,7 +42,12 @@ void WriteMultiExecExpression(ITypeSymbol elementType, string castType)
             // return Command<type>(...).ExecuteAsync((cast)param, ...);
             bool isAsync = HasAny(flags, OperationFlags.Async);
             sb.Append("Execute").Append(isAsync ? "Async" : "").Append("(");
-            sb.Append("(").Append(castType).Append(")param!").Append(");");
+            sb.Append("(").Append(castType).Append(")param!");
+            if (isAsync && HasParam(methodParameters, "cancellationToken"))
+            {
+                sb.Append(", cancellationToken: ").Append(Forward(methodParameters, "cancellationToken"));
+            }
+            sb.Append(");");
             sb.NewLine().Outdent().NewLine().NewLine();
         }
 

src/Dapper.AOT.Analyzers/CodeAnalysis/DapperInterceptorGenerator.Single.cs

@@ -15,10 +15,11 @@ void WriteSingleImplementation(
         OperationFlags commandTypeMode,
         ITypeSymbol? parameterType,
         string map, bool cache,
-        ImmutableArray<IParameterSymbol> methodParameters,
-        CommandFactoryState factories,
-        RowReaderState readers,
-        string? fixedSql)
+        in ImmutableArray<IParameterSymbol> methodParameters,
+        in CommandFactoryState factories,
+        in RowReaderState readers,
+        string? fixedSql,
+        in EstimatedRowCountState estimatedRowCount)
     {
         sb.Append("return ");
         if (HasAll(flags, OperationFlags.Async | OperationFlags.Query | OperationFlags.Buffered))
@@ -188,9 +189,20 @@ static bool IsInbuilt(ITypeSymbol? type, out string? helper)
         {
             sb.NewLine().Append("#error not supported: ").Append(method.Name).NewLine();
         }
-        if (isAsync)
+        if (HasAny(flags, OperationFlags.Query) && estimatedRowCount.HasValue)
         {
-            sb.Append(", ").Append(Forward(methodParameters, "cancellationToken"));
+            if (estimatedRowCount.MemberName is null)
+            {
+                sb.Append(", rowCountHint: ").Append(estimatedRowCount.Count);
+            }
+            else if (parameterType is not null && !parameterType.IsAnonymousType)
+            {
+                sb.Append(", rowCountHint: ((").Append(parameterType).Append(")param!).").Append(estimatedRowCount.MemberName);
+            }
+        }
+        if (isAsync && HasParam(methodParameters, "cancellationToken"))
+        {
+            sb.Append(", cancellationToken: ").Append(Forward(methodParameters, "cancellationToken"));
         }
         if (HasAll(flags, OperationFlags.Async | OperationFlags.Query | OperationFlags.Buffered))
         {

src/Dapper.AOT.Analyzers/CodeAnalysis/DapperInterceptorGenerator.cs

@@ -337,9 +337,10 @@ private bool PreFilter(SyntaxNode node, CancellationToken cancellationToken)
             if (!canBeCached) flags &= ~OperationFlags.CacheCommand;
         }
 
+        var estimatedRowCount = ReadEstimatedRowCount(ctx, op, paramType, ref diagnostics, cancellationToken);
         CheckCallValidity(op, flags, ref diagnostics);
 
-        return new SourceState(loc, op.TargetMethod, flags, sql, resultType, paramType, parameterMap, diagnostics);
+        return new SourceState(loc, op.TargetMethod, flags, sql, resultType, paramType, parameterMap, estimatedRowCount, diagnostics);
 
         //static bool HasDiagnostic(object? diagnostics, DiagnosticDescriptor diagnostic)
         //{
@@ -361,6 +362,46 @@ private bool PreFilter(SyntaxNode node, CancellationToken cancellationToken)
         static bool TryGetConstantValue<T>(IArgumentOperation op, out T? value)
             => TryGetConstantValueWithSyntax<T>(op, out value, out _);
 
+        static EstimatedRowCountState ReadEstimatedRowCount(GeneratorSyntaxContext ctx, IOperation op, ITypeSymbol? paramType, ref object? diagnostics, CancellationToken cancellationToken)
+        {
+            string? estimatedRowCountMember = null;
+            if (paramType is not null)
+            {
+                foreach (var member in Inspection.GetMembers(paramType))
+                {
+                    if (member.IsEstimatedRowCount)
+                    {
+                        if (estimatedRowCountMember is not null)
+                        {
+                            Diagnostics.Add(ref diagnostics, Diagnostic.Create(Diagnostics.MemberRowCountHintDuplicated, member.GetLocation()));
+                        }
+                        estimatedRowCountMember = member.Member.Name;
+                    }
+                }
+            }
+            var attrib = Inspection.GetClosestDapperAttribute(in ctx, op, Types.EstimatedRowCountAttribute, out var attribLoc, cancellationToken);
+
+            if (estimatedRowCountMember is not null)
+            {
+                if (attrib is not null)
+                {
+                    Diagnostics.Add(ref diagnostics, Diagnostic.Create(Diagnostics.MethodRowCountHintRedundant, attribLoc, estimatedRowCountMember));
+                }
+                return new EstimatedRowCountState(estimatedRowCountMember);
+            }
+
+            if (attrib is not null)
+            {
+                if (attrib.ConstructorArguments.Length == 1 && attrib.ConstructorArguments[0].Value is int i
+                    && i > 0)
+                {
+                    return new EstimatedRowCountState(i);
+                }
+                Diagnostics.Add(ref diagnostics, Diagnostic.Create(Diagnostics.MethodRowCountHintInvalid, attribLoc));
+            }
+            return default;
+        }
+
         static bool TryGetConstantValueWithSyntax<T>(IArgumentOperation op, out T? value, out SyntaxNode? syntax)
         {
             try
@@ -510,6 +551,9 @@ select var.Name.StartsWith("@") ? var.Name.Substring(1) : var.Name
                     {
                         Diagnostics.Add(ref diagnostics, Diagnostic.Create(Diagnostics.RowCountDbValue, loc, member.CodeName));
                     }
+                }
+                if (member.Kind != Inspection.ElementMemberKind.None)
+                {
                     continue; // not treated as parameters for naming etc purposes
                 }
                 var dbName = member.DbName;
@@ -885,24 +929,8 @@ private void Generate(SourceProductionContext ctx, (Compilation Compilation, Imm
         foreach (var grp in state.Nodes.Where(x => !HasAny(x.Flags, OperationFlags.DoNotGenerate)).GroupBy(x => x.Group(), CommonComparer.Instance))
         {
             // first, try to resolve the helper method that we're going to use for this
-            var (flags, method, parameterType, parameterMap, _) = grp.Key;
-            int arity = HasAny(flags, OperationFlags.TypedResult) ? 2 : 1, argCount = 8;
+            var (flags, method, parameterType, parameterMap, _, estimatedRowCount) = grp.Key;
             const bool useUnsafe = false;
-            var helperName = method.Name;
-            if (helperName == "Query")
-            {
-                if (HasAny(flags, OperationFlags.Buffered | OperationFlags.Unbuffered))
-                {
-                    //dedicated mode
-                    helperName = HasAny(flags, OperationFlags.Buffered) ? "QueryBuffered" : "QueryUnbuffered";
-                }
-                else
-                {
-                    // fallback mode, needs an extra arg to pass in "buffered"
-                    argCount++;
-                }
-            }
-
             int usageCount = 0;
 
             foreach (var op in grp.OrderBy(row => row.Location, CommonComparer.Instance))
@@ -988,7 +1016,7 @@ private void Generate(SourceProductionContext ctx, (Compilation Compilation, Imm
 
             if (!TryWriteMultiExecImplementation(sb, flags, commandTypeMode, parameterType, grp.Key.ParameterMap, grp.Key.UniqueLocation is not null, methodParameters, factories, fixedSql))
             {
-                WriteSingleImplementation(sb, method, resultType, flags, commandTypeMode, parameterType, grp.Key.ParameterMap, grp.Key.UniqueLocation is not null, methodParameters, factories, readers, fixedSql);
+                WriteSingleImplementation(sb, method, resultType, flags, commandTypeMode, parameterType, grp.Key.ParameterMap, grp.Key.UniqueLocation is not null, methodParameters, factories, readers, fixedSql, estimatedRowCount);
             }
         }
 
@@ -1630,8 +1658,10 @@ sealed class SourceState
         public IMethodSymbol Method { get; }
         public ITypeSymbol? ResultType { get; }
         public ITypeSymbol? ParameterType { get; }
+        public EstimatedRowCountState EstimatedRowCount { get; }
         public SourceState(Location location, IMethodSymbol method, OperationFlags flags, string? sql,
-            ITypeSymbol? resultType, ITypeSymbol? parameterType, string parameterMap, object? diagnostics = null)
+            ITypeSymbol? resultType, ITypeSymbol? parameterType, string parameterMap,
+            EstimatedRowCountState estimatedRowCount, object? diagnostics = null)
         {
             Location = location;
             Flags = flags;
@@ -1640,6 +1670,7 @@ public SourceState(Location location, IMethodSymbol method, OperationFlags flags
             ParameterType = parameterType;
             Method = method;
             ParameterMap = parameterMap;
+            EstimatedRowCount = estimatedRowCount;
             this.diagnostics = diagnostics;
         }
 
@@ -1658,21 +1689,25 @@ public SourceState(Location location, IMethodSymbol method, OperationFlags flags
             _ => throw new IndexOutOfRangeException(nameof(index)),
         };
 
-        public (OperationFlags Flags, IMethodSymbol Method, ITypeSymbol? ParameterType, string ParameterMap, Location? UniqueLocation) Group()
-            => new(Flags, Method, ParameterType, ParameterMap, (Flags & (OperationFlags.CacheCommand | OperationFlags.IncludeLocation)) == 0 ? null : Location);
+        public (OperationFlags Flags, IMethodSymbol Method, ITypeSymbol? ParameterType, string ParameterMap, Location? UniqueLocation, EstimatedRowCountState EstimatedRowCount) Group()
+            => new(Flags, Method, ParameterType, ParameterMap, (Flags & (OperationFlags.CacheCommand | OperationFlags.IncludeLocation)) == 0 ? null : Location, EstimatedRowCount);
     }
-    private sealed class CommonComparer : LocationComparer, IEqualityComparer<(OperationFlags Flags, IMethodSymbol Method, ITypeSymbol? ParameterType, string ParameterMap, Location? UniqueLocation)>
+    private sealed class CommonComparer : LocationComparer, IEqualityComparer<(OperationFlags Flags, IMethodSymbol Method, ITypeSymbol? ParameterType, string ParameterMap, Location? UniqueLocation, EstimatedRowCountState EstimatedRowCount)>
     {
         public static readonly CommonComparer Instance = new();
         private CommonComparer() { }
 
-        public bool Equals((OperationFlags Flags, IMethodSymbol Method, ITypeSymbol? ParameterType, string ParameterMap, Location? UniqueLocation) x, (OperationFlags Flags, IMethodSymbol Method, ITypeSymbol? ParameterType, string ParameterMap, Location? UniqueLocation) y) => x.Flags == y.Flags
+        public bool Equals(
+
+            (OperationFlags Flags, IMethodSymbol Method, ITypeSymbol? ParameterType, string ParameterMap, Location? UniqueLocation, EstimatedRowCountState EstimatedRowCount) x,
+            (OperationFlags Flags, IMethodSymbol Method, ITypeSymbol? ParameterType, string ParameterMap, Location? UniqueLocation, EstimatedRowCountState EstimatedRowCount) y) => x.Flags == y.Flags
                 && x.ParameterMap == y.ParameterMap
                 && SymbolEqualityComparer.Default.Equals(x.Method, y.Method)
                 && SymbolEqualityComparer.Default.Equals(x.ParameterType, y.ParameterType)
-                && x.UniqueLocation == y.UniqueLocation;
+                && x.UniqueLocation == y.UniqueLocation
+                && x.EstimatedRowCount.Equals(y.EstimatedRowCount);
 
-        public int GetHashCode((OperationFlags Flags, IMethodSymbol Method, ITypeSymbol? ParameterType, string ParameterMap, Location? UniqueLocation) obj)
+        public int GetHashCode((OperationFlags Flags, IMethodSymbol Method, ITypeSymbol? ParameterType, string ParameterMap, Location? UniqueLocation, EstimatedRowCountState EstimatedRowCount) obj)
         {
             var hash = (int)obj.Flags;
             hash *= -47;
@@ -1689,6 +1724,8 @@ public int GetHashCode((OperationFlags Flags, IMethodSymbol Method, ITypeSymbol?
             {
                 hash += obj.UniqueLocation.GetHashCode();
             }
+            hash *= -47;
+            hash += obj.EstimatedRowCount.GetHashCode();
             return hash;
         }
     }

src/Dapper.AOT.Analyzers/CodeAnalysis/Diagnostics.cs

@@ -66,6 +66,14 @@ internal static readonly DiagnosticDescriptor
             "Use {0}() instead of Query(...).{1}()", Category.Performance, DiagnosticSeverity.Warning, true),
         UseQueryAsList = new("DAP028", "Use AsList instead of ToList",
             "Use Query(...).AsList() instead of Query(...).ToList()", Category.Performance, DiagnosticSeverity.Warning, true),
+        MethodRowCountHintRedundant = new("DAP029", "Method-level row-count hint redundant",
+            "The [EstimatedRowCount] will be ignored due to parameter member '{0}'", Category.Library, DiagnosticSeverity.Info, true),
+        MethodRowCountHintInvalid = new("DAP030", "Method-level row-count hint invalid",
+            "The [EstimatedRowCount] parameters are invalid; a positive integer must be supplied", Category.Library, DiagnosticSeverity.Error, true),
+        MemberRowCountHintInvalid = new("DAP031", "Member-level row-count hint invalid",
+            "The [EstimatedRowCount] parameters are invalid; no parameter should be supplied", Category.Library, DiagnosticSeverity.Error, true),
+        MemberRowCountHintDuplicated = new("DAP032", "Member-level row-count hint duplicated",
+            "Only a single member should be marked [EstimatedRowCount]", Category.Library, DiagnosticSeverity.Error, true),
 
     // TypeAccessor
         TypeAccessorCollectionTypeNotAllowed = new("DAP100", "TypeAccessors does not allow collection types",

src/Dapper.AOT.Analyzers/Internal/CommandFactoryState.cs

@@ -8,6 +8,7 @@ namespace Dapper.Internal;
 
 internal readonly struct CommandFactoryState : IEnumerable<(ITypeSymbol Type, string Map, int Index, int CacheCount)>
 {
+
     public CommandFactoryState(Compilation compilation) => systemObject = compilation.GetSpecialType(SpecialType.System_Object);
     private readonly ITypeSymbol systemObject;
     private readonly Dictionary<(ITypeSymbol Type, string Map, bool Cached), (int Index, int CacheCount)> parameterTypes = new(ParameterTypeMapComparer.Instance);

src/Dapper.AOT.Analyzers/Internal/EstimatedRowCountState.cs

@@ -0,0 +1,33 @@
+using System;
+
+namespace Dapper.Internal;
+
+internal readonly struct EstimatedRowCountState : IEquatable<EstimatedRowCountState>
+{
+    public readonly int Count;
+    public readonly string? MemberName;
+    public bool HasValue => Count > 0 || MemberName is not null;
+
+    public EstimatedRowCountState(string memberName)
+    {
+        Count = 0;
+        MemberName = memberName;
+    }
+
+    public EstimatedRowCountState(int count)
+    {
+        Count = count;
+        MemberName = null;
+    }
+
+    public override bool Equals(object obj) => obj is EstimatedRowCountState other && Equals(other);
+
+    public bool Equals(EstimatedRowCountState other)
+        => Count == other.Count && MemberName == other.MemberName;
+
+    public override int GetHashCode()
+        => Count + (MemberName is null ? 0 : MemberName.GetHashCode());
+
+    public override string ToString() => MemberName is null
+        ? Count.ToString() : MemberName;
+}