[Experimental] Use System.HashCode instead of JSONConvert.SerializeObject

PowerSync/PowerSync.Common/Client/Sync/Bucket/BucketStorageAdapter.cs

@@ -2,6 +2,7 @@
 namespace PowerSync.Common.Client.Sync.Bucket;
 
 using System;
+using System.Linq;
 using System.Threading.Tasks;
 
 using PowerSync.Common.DB.Crud;
@@ -54,12 +55,18 @@ public class SyncLocalDatabaseResult
     public override bool Equals(object? obj)
     {
         if (obj is not SyncLocalDatabaseResult other) return false;
-        return JsonConvert.SerializeObject(this) == JsonConvert.SerializeObject(other);
+        return Ready == other.Ready
+            && CheckpointValid == other.CheckpointValid
+            && CompareUtils.ArraysEqual(CheckpointFailures, other.CheckpointFailures);
     }
 
     public override int GetHashCode()
     {
-        return JsonConvert.SerializeObject(this).GetHashCode();
+        return HashCode.Combine(
+            Ready,
+            CheckpointValid,
+            HashUtils.GetHashCodeArray(CheckpointFailures)
+        );
     }
 }
 
@@ -129,4 +136,4 @@ public interface IBucketStorageAdapter : IEventStream<BucketStorageEvent>
     /// Invokes the `powersync_control` function for the sync client.
     /// </summary>
     Task<string> Control(string op, object? payload);
-}
+}

PowerSync/PowerSync.Common/DB/Crud/CrudEntry.cs

@@ -3,6 +3,8 @@ namespace PowerSync.Common.DB.Crud;
 using System.Collections.Generic;
 using Newtonsoft.Json;
 
+using PowerSync.Common.Utils;
+
 public enum UpdateType
 {
     [JsonProperty("PUT")]
@@ -90,11 +92,23 @@ public static CrudEntry FromRow(CrudEntryJSON dbRow)
     public override bool Equals(object? obj)
     {
         if (obj is not CrudEntry other) return false;
-        return JsonConvert.SerializeObject(this) == JsonConvert.SerializeObject(other);
+        return ClientId == other.ClientId
+          && Id == other.Id
+          && Op == other.Op
+          && TransactionId == other.TransactionId
+          && Table == other.Table
+          && CompareUtils.DictionariesEqual(OpData, other.OpData);
     }
 
     public override int GetHashCode()
     {
-        return JsonConvert.SerializeObject(this).GetHashCode();
+        return HashCode.Combine(
+            ClientId,
+            Id,
+            Op,
+            Table,
+            TransactionId,
+            HashUtils.GetHashCodeDictionary(OpData)
+        );
     }
-}
+}

PowerSync/PowerSync.Common/PowerSync.Common.csproj

@@ -31,6 +31,13 @@
     <PackageReference Include="System.Threading.Channels" Version="8.0.0" />
   </ItemGroup>
 
+  <!-- System.HashCode polyfill for .NET Standard 2.0 and .NET Framework 4.8 -->
+  <ItemGroup Condition="$(TargetFramework) == 'net48' OR $(TargetFramework) == 'netstandard2.0'">
+    <PackageReference Include="Microsoft.Bcl.HashCode">
+      <Version>6.0.0</Version>
+    </PackageReference>
+  </ItemGroup>
+
   <ItemGroup>
     <None Include="PowerSync.Common.targets" Pack="true" PackagePath="build\" />
     <None Include="PowerSync.Common.targets" Pack="true" PackagePath="buildTransitive\" />
@@ -50,7 +57,7 @@
   </ItemGroup>
 
   <ItemGroup>
-    <None Include="..\..\icon.png" Pack="true" PackagePath=""/>
-    <None Include="README.md" Pack="true" PackagePath=""/>
+    <None Include="..\..\icon.png" Pack="true" PackagePath="" />
+    <None Include="README.md" Pack="true" PackagePath="" />
   </ItemGroup>
 </Project>

PowerSync/PowerSync.Common/Utils/CompareUtils.cs

@@ -0,0 +1,43 @@
+namespace PowerSync.Common.Utils;
+
+using System.Collections.Generic;
+using System.Linq;
+
+public static class CompareUtils
+{
+    /// <summary>
+    /// Compare two dictionaries by value. Checks if both dictionaries have both the same 
+    /// number of keys, as well as the same keys pointing to the same values.
+    /// </summary>
+    public static bool DictionariesEqual<TKey, TValue>(Dictionary<TKey, TValue>? dict1, Dictionary<TKey, TValue>? dict2)
+    {
+        if (ReferenceEquals(dict1, dict2)) return true;
+        if (dict1 == null || dict2 == null) return false;
+        if (dict1.Count != dict2.Count) return false;
+
+        var comparer = EqualityComparer<TValue>.Default;
+
+        foreach (var keyValuePair in dict1)
+        {
+            if (!dict2.TryGetValue(keyValuePair.Key, out TValue secondValue) ||
+              !comparer.Equals(keyValuePair.Value, secondValue))
+            {
+                return false;
+            }
+        }
+
+        return true;
+    }
+
+    /// <summary>
+    /// Check if two (maybe null) arrays contain the same elements in the same order.
+    /// Effectively arr1.SequenceEqual(arr2), but with null checks.
+    /// </summary>
+    public static bool ArraysEqual<TValue>(TValue[]? arr1, TValue[]? arr2)
+    {
+        if (ReferenceEquals(arr1, arr2)) return true;
+        if (arr1 == null || arr2 == null) return false;
+        return arr1.SequenceEqual(arr2);
+    }
+}
+

PowerSync/PowerSync.Common/Utils/HashUtils.cs

@@ -0,0 +1,47 @@
+namespace PowerSync.Common.Utils;
+
+using System;
+using System.Collections.Generic;
+
+public static class HashUtils
+{
+    /// <summary>
+    /// Create a hash from the key-value pairs in a dictionary. The hash does not depend
+    /// on the internal pair ordering of the dictionary.
+    /// </summary>
+    public static int GetHashCodeDictionary<TKey, TValue>(Dictionary<TKey, TValue>? dict)
+    {
+        if (dict == null)
+        {
+            return 0;
+        }
+
+        // Use integer hash because order matters with System.HashCode
+        int hash = 0;
+        foreach (var kvp in dict)
+        {
+            // Combine hashes with XOR so that order doesn't matter
+            hash ^= HashCode.Combine(kvp.Key, kvp.Value);
+        }
+        return hash;
+    }
+
+    /// <summary>
+    /// Create a hash from an array of values. The hash depends on the order of
+    /// elements in the array.
+    /// </summary>
+    public static int GetHashCodeArray<TValue>(TValue[]? values)
+    {
+        if (values == null)
+        {
+            return 0;
+        }
+
+        HashCode hash = new HashCode();
+        foreach (var value in values)
+        {
+            hash.Add(value);
+        }
+        return hash.ToHashCode();
+    }
+}