Avoid potential allocation when using lambdas.

Author: electricessence

Open.ChannelExtensions/BatchingChannelReader.cs

@@ -41,6 +41,8 @@ public BatchingChannelReader(
 	/// </summary>
 	public bool ForceBatch() => TryPipeItems(true);
 
+	void ForceBatch(object obj) => ForceBatch();
+
 	long _timeout = -1;
 	Timer? _timer;
 
@@ -67,7 +69,7 @@ public BatchingChannelReader<T> WithTimeout(long millisecondsTimeout)
 		}
 
 		LazyInitializer.EnsureInitialized(ref _timer,
-			() => new Timer(obj => ForceBatch()));
+			() => new Timer(ForceBatch));
 
 		if (_batch is null) return this;
 

Open.ChannelExtensions/Documentation.xml

@@ -28,9 +28,12 @@ public static async ValueTask<long> PipeTo<T>(this ChannelReader<T> source,
 		if (target is null) throw new ArgumentNullException(nameof(target));
 		Contract.EndContractBlock();
 
+		// Acceptable closure.
+		ValueTask WriteTarget(T e) => target.WriteAsync(e, cancellationToken);
+
 		try
 		{
-			return await source.ReadAllAsync(e => target.WriteAsync(e, cancellationToken), cancellationToken).ConfigureAwait(false);
+			return await source.ReadAllAsync(WriteTarget, cancellationToken).ConfigureAwait(false);
 		}
 		catch (Exception ex)
 		{

Open.ChannelExtensions/Extensions.Pipe.cs

@@ -2,7 +2,6 @@
 using System.Collections.Generic;
 using System.Diagnostics.Contracts;
 using System.IO;
-using System.Linq;
 using System.Threading;
 using System.Threading.Channels;
 using System.Threading.Tasks;
@@ -108,7 +107,7 @@ public static ValueTask<long> WriteAllAsync<T>(
 
 		return WriteAllAsync(
 			target,
-			source.Select(e => new ValueTask<T>(e)),
+			source.WrapValueTask(),
 			complete,
 			deferredExecution,
 			cancellationToken);
@@ -155,7 +154,7 @@ public static ValueTask<long> WriteAllAsync<T>(
 
 		return WriteAllAsync(
 			target,
-			source.Select(e => new ValueTask<T>(e())),
+			source.WrapValueTask(),
 			complete,
 			deferredExecution,
 			cancellationToken);
@@ -202,7 +201,7 @@ public static ValueTask<long> WriteAll<T>(
 
 		return WriteAllAsync(
 			target,
-			source.Select(e => new ValueTask<T>(e)),
+			source.WrapValueTask(),
 			complete,
 			deferredExecution,
 			cancellationToken);
@@ -309,6 +308,8 @@ public static ValueTask<long> WriteAllLines(
 		CancellationToken cancellationToken)
 		=> WriteAllLines(target, source, complete, false, cancellationToken);
 
+
+
 #if NETSTANDARD2_1
 	/// <summary>
 	/// Asynchronously writes all entries from the source to the channel.

Open.ChannelExtensions/Extensions.Write.cs

@@ -141,7 +141,7 @@ public static Task<long> WriteAllConcurrentlyAsync<T>(
 		IEnumerable<Task<T>> source,
 		bool complete = false,
 		CancellationToken cancellationToken = default)
-		=> WriteAllConcurrentlyAsync(target, maxConcurrency, source.Select(e => new ValueTask<T>(e)), complete, cancellationToken);
+		=> WriteAllConcurrentlyAsync(target, maxConcurrency, source.WrapValueTask(), complete, cancellationToken);
 
 	/// <summary>
 	/// Asynchronously executes all entries and writes their results to the channel.
@@ -160,5 +160,5 @@ public static Task<long> WriteAllConcurrentlyAsync<T>(
 		IEnumerable<Func<T>> source,
 		bool complete = false,
 		CancellationToken cancellationToken = default)
-		=> WriteAllConcurrentlyAsync(target, maxConcurrency, source.Select(e => new ValueTask<T>(e())), complete, cancellationToken);
+		=> WriteAllConcurrentlyAsync(target, maxConcurrency, source.WrapValueTask(), complete, cancellationToken);
 }

Open.ChannelExtensions/Extensions.WriteConcurrently.cs

@@ -46,6 +46,25 @@ static async ValueTask ThrowChannelClosedExceptionIfFalse(ValueTask<bool> write,
 		}
 	}
 
+	// Avoid potential lambda allocation.
+	internal static IEnumerable<ValueTask<T>> WrapValueTask<T>(this IEnumerable<T> source)
+	{
+		foreach (var e in source)
+			yield return new ValueTask<T>(e);
+	}
+
+	internal static IEnumerable<ValueTask<T>> WrapValueTask<T>(this IEnumerable<Task<T>> source)
+	{
+		foreach (var e in source)
+			yield return new ValueTask<T>(e);
+	}
+
+	internal static IEnumerable<ValueTask<T>> WrapValueTask<T>(this IEnumerable<Func<T>> source)
+	{
+		foreach (var e in source)
+			yield return new ValueTask<T>(e());
+	}
+
 	/// <summary>
 	/// Waits for opportunity to write to a channel and throws a ChannelClosedException if the channel is closed.  
 	/// </summary>