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Merged
mgravell merged 1 commit into from
Mar 27, 2025
Merged

cached-command should use a backing pool, in particular for async APIs #150

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10 changes: 7 additions & 3 deletions src/Dapper.AOT.Analyzers/CodeAnalysis/DapperInterceptorGenerator.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -579,30 +579,34 @@ private static void WriteCommandFactory(in GenerateState ctx, string baseFactory
if (additionalCommandState is not null && additionalCommandState.HasCommandProperties)
{
sb.Indent()
.NewLine().Append("var cmd = TryReuse(ref Storage, sql, commandType, args);")
.NewLine().Append("var cmd = TryReuseThreadStatic(ref Storage, sql, commandType, args, _cmdPool);")
.NewLine().Append("if (cmd is null)").Indent()
.NewLine().Append("cmd = base.GetCommand(connection, sql, commandType, args);");
WriteCommandProperties(ctx, sb, "cmd", additionalCommandState.CommandProperties);
sb.Outdent().NewLine().Append("return cmd;").Outdent();
}
else
{
sb.Indent(false).NewLine().Append(" => TryReuse(ref Storage, sql, commandType, args) ?? base.GetCommand(connection, sql, commandType, args);").Outdent(false);
sb.Indent(false).NewLine().Append(" => TryReuseThreadStatic(ref Storage, sql, commandType, args, _cmdPool) ?? base.GetCommand(connection, sql, commandType, args);").Outdent(false);
}
sb.NewLine().NewLine().Append("public override bool TryRecycle(global::System.Data.Common.DbCommand command) => TryRecycle(ref Storage, command);").NewLine();
sb.NewLine().NewLine().Append("public override bool TryRecycle(global::System.Data.Common.DbCommand command) => TryRecycleThreadStatic(ref Storage, command, _cmdPool);").NewLine();

if (cacheCount == 1)
{
sb.Append("private static readonly DbCommandCache _cmdPool = new();").NewLine();
sb.Append("[global::System.ThreadStatic] // note this works correctly with ref").NewLine();
sb.Append("private static global::System.Data.Common.DbCommand? Storage;").NewLine();
}
else
{
sb.Append("private readonly DbCommandCache _cmdPool = new(); // note: per cache instance").NewLine();
sb.Append("protected abstract ref global::System.Data.Common.DbCommand? Storage {get;}").NewLine().NewLine();

for (int i = 0; i < cacheCount; i++)
{
sb.Append("internal sealed class Cached").Append(i).Append(" : CommandFactory").Append(index).Indent().NewLine()
.Append("protected override ref global::System.Data.Common.DbCommand? Storage => ref s_Storage;").NewLine()
.Append("[global::System.ThreadStatic] // note this works correctly with ref-return").NewLine()
.Append("private static global::System.Data.Common.DbCommand? s_Storage;").NewLine()
.Outdent().NewLine();
}
Expand Down
67 changes: 63 additions & 4 deletions src/Dapper.AOT/CommandFactory.cs
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Original file line number Diff line number Diff line change
@@ -1,5 +1,6 @@
using Dapper.Internal;
using System;
using System.Collections.Concurrent;
using System.Data;
using System.Data.Common;
using System.Diagnostics;
Expand Down Expand Up @@ -175,12 +176,53 @@ protected static void SetValueWithDefaultSize(DbParameter parameter, string? val
/// <summary>
/// Provides an opportunity to recycle and reuse command instances
/// </summary>
protected static bool TryRecycle(ref DbCommand? storage, DbCommand command)
protected static bool TryRecycleInterlocked(ref DbCommand? storage, DbCommand command, DbCommandCache? cache = null)
{
// detach and recycle
command.Connection = null;
command.Transaction = null;
return Interlocked.CompareExchange(ref storage, command, null) is null;
if (Interlocked.CompareExchange(ref storage, command, null) is null)
{
return true;
}
return cache is not null && cache.TryPut(command);
}

/// <summary>
/// Provides an opportunity to recycle and reuse command instances
/// </summary>
protected static bool TryRecycleThreadStatic(ref DbCommand? storage, DbCommand command, DbCommandCache? cache = null)
{
// detach and recycle
command.Connection = null;
command.Transaction = null;
if (storage is null)
{
storage = command;
return true;
}
return cache is not null && cache.TryPut(command);
}


/// <summary>
/// A simple store for command re-use.
/// </summary>
protected sealed class DbCommandCache(int capacity = 16)
{
private readonly ConcurrentQueue<DbCommand> store = [];
internal bool TryPut(DbCommand command)
{
if (store.Count < capacity) // not exact - inherent race condition
{
store.Enqueue(command);
return true;
}
return false;
}

internal DbCommand? TryTake()
=> store.TryDequeue(out var cmd) ? cmd : null;
}
}

Expand Down Expand Up @@ -252,9 +294,26 @@ public virtual void UpdateParameters(in UnifiedCommand command, T args)
/// <summary>
/// Provides an opportunity to recycle and reuse command instances
/// </summary>
protected DbCommand? TryReuse(ref DbCommand? storage, string sql, CommandType commandType, T args)
protected DbCommand? TryReuseThreadStatic(ref DbCommand? storage, string sql, CommandType commandType, T args, DbCommandCache? cache = null)
{
var cmd = storage ?? cache?.TryTake();
storage = null;
if (cmd is not null)
{
// try to avoid any dirty detection in the setters
if (cmd.CommandText != sql) cmd.CommandText = sql;
if (cmd.CommandType != commandType) cmd.CommandType = commandType;
UpdateParameters(new(cmd), args);
}
return cmd;
}

/// <summary>
/// Provides an opportunity to recycle and reuse command instances
/// </summary>
protected DbCommand? TryReuseInterlocked(ref DbCommand? storage, string sql, CommandType commandType, T args, DbCommandCache? cache = null)
{
var cmd = Interlocked.Exchange(ref storage, null);
var cmd = Interlocked.Exchange(ref storage, null) ?? cache?.TryTake();
if (cmd is not null)
{
// try to avoid any dirty detection in the setters
Expand Down
13 changes: 9 additions & 4 deletions test/Dapper.AOT.Test/Interceptors/CacheCommand.output.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -118,20 +118,23 @@ public override void UpdateParameters(in global::Dapper.UnifiedCommand cmd, obje

public override global::System.Data.Common.DbCommand GetCommand(global::System.Data.Common.DbConnection connection,
string sql, global::System.Data.CommandType commandType, object? args)
=> TryReuse(ref Storage, sql, commandType, args) ?? base.GetCommand(connection, sql, commandType, args);
=> TryReuseThreadStatic(ref Storage, sql, commandType, args, _cmdPool) ?? base.GetCommand(connection, sql, commandType, args);

public override bool TryRecycle(global::System.Data.Common.DbCommand command) => TryRecycle(ref Storage, command);
public override bool TryRecycle(global::System.Data.Common.DbCommand command) => TryRecycleThreadStatic(ref Storage, command, _cmdPool);
private readonly DbCommandCache _cmdPool = new(); // note: per cache instance
protected abstract ref global::System.Data.Common.DbCommand? Storage {get;}

internal sealed class Cached0 : CommandFactory0
{
protected override ref global::System.Data.Common.DbCommand? Storage => ref s_Storage;
[global::System.ThreadStatic] // note this works correctly with ref-return
private static global::System.Data.Common.DbCommand? s_Storage;

}
internal sealed class Cached1 : CommandFactory0
{
protected override ref global::System.Data.Common.DbCommand? Storage => ref s_Storage;
[global::System.ThreadStatic] // note this works correctly with ref-return
private static global::System.Data.Common.DbCommand? s_Storage;

}
Expand Down Expand Up @@ -165,9 +168,11 @@ public override void UpdateParameters(in global::Dapper.UnifiedCommand cmd, obje

public override global::System.Data.Common.DbCommand GetCommand(global::System.Data.Common.DbConnection connection,
string sql, global::System.Data.CommandType commandType, object? args)
=> TryReuse(ref Storage, sql, commandType, args) ?? base.GetCommand(connection, sql, commandType, args);
=> TryReuseThreadStatic(ref Storage, sql, commandType, args, _cmdPool) ?? base.GetCommand(connection, sql, commandType, args);

public override bool TryRecycle(global::System.Data.Common.DbCommand command) => TryRecycle(ref Storage, command);
public override bool TryRecycle(global::System.Data.Common.DbCommand command) => TryRecycleThreadStatic(ref Storage, command, _cmdPool);
private static readonly DbCommandCache _cmdPool = new();
[global::System.ThreadStatic] // note this works correctly with ref
private static global::System.Data.Common.DbCommand? Storage;

}
Expand Down
13 changes: 9 additions & 4 deletions test/Dapper.AOT.Test/Interceptors/CacheCommand.output.netfx.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -118,20 +118,23 @@ public override void UpdateParameters(in global::Dapper.UnifiedCommand cmd, obje

public override global::System.Data.Common.DbCommand GetCommand(global::System.Data.Common.DbConnection connection,
string sql, global::System.Data.CommandType commandType, object? args)
=> TryReuse(ref Storage, sql, commandType, args) ?? base.GetCommand(connection, sql, commandType, args);
=> TryReuseThreadStatic(ref Storage, sql, commandType, args, _cmdPool) ?? base.GetCommand(connection, sql, commandType, args);

public override bool TryRecycle(global::System.Data.Common.DbCommand command) => TryRecycle(ref Storage, command);
public override bool TryRecycle(global::System.Data.Common.DbCommand command) => TryRecycleThreadStatic(ref Storage, command, _cmdPool);
private readonly DbCommandCache _cmdPool = new(); // note: per cache instance
protected abstract ref global::System.Data.Common.DbCommand? Storage {get;}

internal sealed class Cached0 : CommandFactory0
{
protected override ref global::System.Data.Common.DbCommand? Storage => ref s_Storage;
[global::System.ThreadStatic] // note this works correctly with ref-return
private static global::System.Data.Common.DbCommand? s_Storage;

}
internal sealed class Cached1 : CommandFactory0
{
protected override ref global::System.Data.Common.DbCommand? Storage => ref s_Storage;
[global::System.ThreadStatic] // note this works correctly with ref-return
private static global::System.Data.Common.DbCommand? s_Storage;

}
Expand Down Expand Up @@ -165,9 +168,11 @@ public override void UpdateParameters(in global::Dapper.UnifiedCommand cmd, obje

public override global::System.Data.Common.DbCommand GetCommand(global::System.Data.Common.DbConnection connection,
string sql, global::System.Data.CommandType commandType, object? args)
=> TryReuse(ref Storage, sql, commandType, args) ?? base.GetCommand(connection, sql, commandType, args);
=> TryReuseThreadStatic(ref Storage, sql, commandType, args, _cmdPool) ?? base.GetCommand(connection, sql, commandType, args);

public override bool TryRecycle(global::System.Data.Common.DbCommand command) => TryRecycle(ref Storage, command);
public override bool TryRecycle(global::System.Data.Common.DbCommand command) => TryRecycleThreadStatic(ref Storage, command, _cmdPool);
private static readonly DbCommandCache _cmdPool = new();
[global::System.ThreadStatic] // note this works correctly with ref
private static global::System.Data.Common.DbCommand? Storage;

}
Expand Down
13 changes: 9 additions & 4 deletions test/Dapper.AOT.Test/Interceptors/CommandProperties.output.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -199,7 +199,7 @@ public override void UpdateParameters(in global::Dapper.UnifiedCommand cmd, obje
public override global::System.Data.Common.DbCommand GetCommand(global::System.Data.Common.DbConnection connection,
string sql, global::System.Data.CommandType commandType, object? args)
{
var cmd = TryReuse(ref Storage, sql, commandType, args);
var cmd = TryReuseThreadStatic(ref Storage, sql, commandType, args, _cmdPool);
if (cmd is null)
{
cmd = base.GetCommand(connection, sql, commandType, args);
Expand All @@ -212,7 +212,9 @@ public override void UpdateParameters(in global::Dapper.UnifiedCommand cmd, obje
return cmd;
}

public override bool TryRecycle(global::System.Data.Common.DbCommand command) => TryRecycle(ref Storage, command);
public override bool TryRecycle(global::System.Data.Common.DbCommand command) => TryRecycleThreadStatic(ref Storage, command, _cmdPool);
private readonly DbCommandCache _cmdPool = new();
[global::System.ThreadStatic] // note this works correctly with ref
private static global::System.Data.Common.DbCommand? Storage;

}
Expand Down Expand Up @@ -256,7 +258,7 @@ public override void UpdateParameters(in global::Dapper.UnifiedCommand cmd, obje
public override global::System.Data.Common.DbCommand GetCommand(global::System.Data.Common.DbConnection connection,
string sql, global::System.Data.CommandType commandType, object? args)
{
var cmd = TryReuse(ref Storage, sql, commandType, args);
var cmd = TryReuseThreadStatic(ref Storage, sql, commandType, args, _cmdPool);
if (cmd is null)
{
cmd = base.GetCommand(connection, sql, commandType, args);
Expand All @@ -269,18 +271,21 @@ public override void UpdateParameters(in global::Dapper.UnifiedCommand cmd, obje
return cmd;
}

public override bool TryRecycle(global::System.Data.Common.DbCommand command) => TryRecycle(ref Storage, command);
public override bool TryRecycle(global::System.Data.Common.DbCommand command) => TryRecycleThreadStatic(ref Storage, command, _cmdPool);
private readonly DbCommandCache _cmdPool = new();
protected abstract ref global::System.Data.Common.DbCommand? Storage {get;}

internal sealed class Cached0 : CommandFactory1
{
protected override ref global::System.Data.Common.DbCommand? Storage => ref s_Storage;
[global::System.ThreadStatic] // note this works correctly with ref-return
private static global::System.Data.Common.DbCommand? s_Storage;

}
internal sealed class Cached1 : CommandFactory1
{
protected override ref global::System.Data.Common.DbCommand? Storage => ref s_Storage;
[global::System.ThreadStatic] // note this works correctly with ref-return
private static global::System.Data.Common.DbCommand? s_Storage;

}
Expand Down
13 changes: 9 additions & 4 deletions test/Dapper.AOT.Test/Interceptors/CommandProperties.output.netfx.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -199,7 +199,7 @@ public override void UpdateParameters(in global::Dapper.UnifiedCommand cmd, obje
public override global::System.Data.Common.DbCommand GetCommand(global::System.Data.Common.DbConnection connection,
string sql, global::System.Data.CommandType commandType, object? args)
{
var cmd = TryReuse(ref Storage, sql, commandType, args);
var cmd = TryReuseThreadStatic(ref Storage, sql, commandType, args, _cmdPool);
if (cmd is null)
{
cmd = base.GetCommand(connection, sql, commandType, args);
Expand All @@ -212,7 +212,9 @@ public override void UpdateParameters(in global::Dapper.UnifiedCommand cmd, obje
return cmd;
}

public override bool TryRecycle(global::System.Data.Common.DbCommand command) => TryRecycle(ref Storage, command);
public override bool TryRecycle(global::System.Data.Common.DbCommand command) => TryRecycleThreadStatic(ref Storage, command, _cmdPool);
private readonly DbCommandCache _cmdPool = new();
[global::System.ThreadStatic] // note this works correctly with ref
private static global::System.Data.Common.DbCommand? Storage;

}
Expand Down Expand Up @@ -256,7 +258,7 @@ public override void UpdateParameters(in global::Dapper.UnifiedCommand cmd, obje
public override global::System.Data.Common.DbCommand GetCommand(global::System.Data.Common.DbConnection connection,
string sql, global::System.Data.CommandType commandType, object? args)
{
var cmd = TryReuse(ref Storage, sql, commandType, args);
var cmd = TryReuseThreadStatic(ref Storage, sql, commandType, args, _cmdPool);
if (cmd is null)
{
cmd = base.GetCommand(connection, sql, commandType, args);
Expand All @@ -269,18 +271,21 @@ public override void UpdateParameters(in global::Dapper.UnifiedCommand cmd, obje
return cmd;
}

public override bool TryRecycle(global::System.Data.Common.DbCommand command) => TryRecycle(ref Storage, command);
public override bool TryRecycle(global::System.Data.Common.DbCommand command) => TryRecycleThreadStatic(ref Storage, command, _cmdPool);
private readonly DbCommandCache _cmdPool = new();
protected abstract ref global::System.Data.Common.DbCommand? Storage {get;}

internal sealed class Cached0 : CommandFactory1
{
protected override ref global::System.Data.Common.DbCommand? Storage => ref s_Storage;
[global::System.ThreadStatic] // note this works correctly with ref-return
private static global::System.Data.Common.DbCommand? s_Storage;

}
internal sealed class Cached1 : CommandFactory1
{
protected override ref global::System.Data.Common.DbCommand? Storage => ref s_Storage;
[global::System.ThreadStatic] // note this works correctly with ref-return
private static global::System.Data.Common.DbCommand? s_Storage;

}
Expand Down
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