fix(storage): a partial PageFileConfig gets LockTimeout.Default, not Immediate (#322)

src/BLite.Core/Storage/LockTimeout.cs

@@ -14,6 +14,11 @@ namespace BLite.Core.Storage;
 /// <c>busy_timeout</c> is 0) or specify custom values to give concurrent callers
 /// time to release contended locks.
 /// </para>
+/// <para>
+/// <c>default(LockTimeout)</c>, or <c>new LockTimeout()</c> with no property set, means
+/// "not specified": <see cref="PageFileConfig.Normalize"/> replaces it with
+/// <see cref="Default"/>. To fail fast, set <see cref="Immediate"/> explicitly.
+/// </para>
 /// </summary>
 public readonly struct LockTimeout : IEquatable<LockTimeout>
 {
@@ -25,7 +30,7 @@ namespace BLite.Core.Storage;
     ///   <item><c>&gt;0</c> — wait up to this many milliseconds.</item>
     /// </list>
     /// </summary>
-    public int ReadTimeoutMs { get; init; }
+    public int ReadTimeoutMs { get => _readTimeoutMs; init { _readTimeoutMs = value; _isSpecified = true; } }
 
     /// <summary>
     /// Timeout for acquiring write locks (milliseconds).
@@ -35,7 +40,7 @@ namespace BLite.Core.Storage;
     ///   <item><c>&gt;0</c> — wait up to this many milliseconds.</item>
     /// </list>
     /// </summary>
-    public int WriteTimeoutMs { get; init; }
+    public int WriteTimeoutMs { get => _writeTimeoutMs; init { _writeTimeoutMs = value; _isSpecified = true; } }
 
     /// <summary>
     /// Maximum number of threads that can simultaneously enter the commit path.
@@ -50,7 +55,18 @@ namespace BLite.Core.Storage;
     ///   <item><c>&gt;0</c> — at most this many concurrent commit operations.</item>
     /// </list>
     /// </summary>
-    public int MaxConcurrentWriters { get; init; }
+    public int MaxConcurrentWriters { get => _maxConcurrentWriters; init { _maxConcurrentWriters = value; _isSpecified = true; } }
+
+    private readonly int _readTimeoutMs;
+    private readonly int _writeTimeoutMs;
+    private readonly int _maxConcurrentWriters;
+    private readonly bool _isSpecified;
+
+    /// <summary>
+    /// <c>false</c> for <c>default(LockTimeout)</c>: no property was set, so the value is
+    /// indistinguishable from <see cref="Immediate"/> but was not chosen. Not part of equality.
+    /// </summary>
+    internal bool IsSpecified => _isSpecified;
 
     /// <summary>
     /// Immediate failure on contention — equivalent to SQLite's default

src/BLite.Core/Storage/PageFile.cs

@@ -46,7 +46,8 @@ public readonly struct PageFileConfig
     /// Lock acquisition timeouts for read and write operations.
     /// Controls how long the engine waits for a contended lock before throwing
     /// <see cref="System.TimeoutException"/> (analogous to SQLite's <c>SQLITE_BUSY</c>).
-    /// Defaults to <see cref="LockTimeout.Default"/> (500 ms read / 500 ms write).
+    /// Defaults to <see cref="LockTimeout.Default"/> (500 ms read / 500 ms write), also when
+    /// the config is built with an object initializer that does not set it.
     /// Use <see cref="LockTimeout.Immediate"/> for fail-fast behaviour.
     /// </summary>
     public LockTimeout LockTimeout { get; init; }
@@ -133,8 +134,9 @@ public readonly struct PageFileConfig
     public bool AllowMultiProcessAccess { get; init; }
 
     /// <summary>
-    /// Returns a copy of this config where any zero-valued numeric fields are replaced
-    /// with the corresponding values from <see cref="Default"/>.
+    /// Returns a copy of this config where any zero-valued numeric fields, and a
+    /// <see cref="LockTimeout"/> that was never set, are replaced with the corresponding
+    /// values from <see cref="Default"/>.
     /// This ensures that a partially-constructed <see cref="PageFileConfig"/>
     /// (e.g. <c>new PageFileConfig { AllowMultiProcessAccess = true }</c>) is always
     /// valid before being handed to the storage engine.
@@ -146,6 +148,7 @@ public PageFileConfig Normalize()
         {
             PageSize        = PageSize        > 0 ? PageSize        : defaults.PageSize,
             GrowthBlockSize = GrowthBlockSize > 0 ? GrowthBlockSize : defaults.GrowthBlockSize,
+            LockTimeout     = LockTimeout.IsSpecified ? LockTimeout : defaults.LockTimeout,
         };
     }
 

tests/BLite.Tests/PageFileConfigLockTimeoutTests.cs

@@ -0,0 +1,34 @@
+using BLite.Core.Storage;
+
+namespace BLite.Tests;
+
+/// <summary>
+/// Regression test for #322: a <see cref="PageFileConfig"/> built with an object initializer
+/// that does not set <see cref="PageFileConfig.LockTimeout"/> used to open with
+/// <c>default(LockTimeout)</c>, which has the same values as <see cref="LockTimeout.Immediate"/>,
+/// so every contended lock failed at once.
+/// </summary>
+public class PageFileConfigLockTimeoutTests
+{
+    [Fact]
+    public void StorageEngine_PartialConfigWithoutLockTimeout_GetsDefault_ExplicitImmediateIsKept()
+    {
+        var dir = Path.Combine(Path.GetTempPath(), $"blite_locktimeout_{Guid.NewGuid():N}");
+        Directory.CreateDirectory(dir);
+        try
+        {
+            using (var engine = new StorageEngine(Path.Combine(dir, "partial.db"), new PageFileConfig { AllowMultiProcessAccess = false }))
+                Assert.Equal(LockTimeout.Default, engine.LockTimeout);
+
+            using (var engine = new StorageEngine(Path.Combine(dir, "immediate.db"), new PageFileConfig { LockTimeout = LockTimeout.Immediate }))
+                Assert.Equal(LockTimeout.Immediate, engine.LockTimeout);
+
+            using (var engine = new StorageEngine(Path.Combine(dir, "from.db"), new PageFileConfig { LockTimeout = LockTimeout.From(0, 0, 0) }))
+                Assert.Equal(LockTimeout.Immediate, engine.LockTimeout);
+        }
+        finally
+        {
+            try { Directory.Delete(dir, recursive: true); } catch { /* best-effort */ }
+        }
+    }
+}