Copy stream when content fits into a queue message

To reduce places where magic could happen

AzureBatchQueue/MessageQueue.cs

@@ -4,7 +4,6 @@
 using Azure.Storage.Queues.Models;
 using Microsoft.Extensions.Logging;
 using Microsoft.Extensions.Logging.Abstractions;
-using JsonSerializer = System.Text.Json.JsonSerializer;
 
 namespace AzureBatchQueue;
 
@@ -39,11 +38,11 @@ public MessageQueue(string connectionString, string queueName,
     public async Task Send(T item, TimeSpan? visibilityTimeout = null, bool doubleCheckSerialization = false, CancellationToken ct = default)
     {
         var (data, offloaded) = await SerializeAndOffloadIfBig(item, ct: ct);
-        await queue.SendMessageAsync(new BinaryData(data), visibilityTimeout ?? TimeSpan.Zero, null, ct);
+        await queue.SendMessageAsync(data, visibilityTimeout ?? TimeSpan.Zero, null, ct);
 
         // Don't ask. Checking our sanity
         if (!offloaded && doubleCheckSerialization)
-            serializer.Deserialize(data.Span);
+            serializer.Deserialize(data);
     }
 
     public async Task DeleteMessage(MessageId id, CancellationToken ct = default)
@@ -62,7 +61,7 @@ public async Task UpdateMessage(MessageId id, T? item, TimeSpan visibilityTimeou
         }
 
         var (data, offloaded) = await SerializeAndOffloadIfBig(item, id.BlobName, ct);
-        await queue.UpdateMessageAsync(id.Id, id.PopReceipt, new BinaryData(data), visibilityTimeout, ct);
+        await queue.UpdateMessageAsync(id.Id, id.PopReceipt, data, visibilityTimeout, ct);
         if (!offloaded && id.BlobName != null)
             await container.DeleteBlobAsync(id.BlobName, cancellationToken: ct);
     }
@@ -72,14 +71,14 @@ async Task<Payload> SerializeAndOffloadIfBig(T item, string? blobName = null, Ca
         using var stream = MemoryStreamManager.RecyclableMemory.GetStream("QueueMessage");
         serializer.Serialize(stream, item);
 
+        stream.Position = 0;
+
         if (stream.Length <= MaxMessageSize)
-            return new Payload(stream.GetBuffer().AsMemory(0, (int)stream.Length), false);
+            return Payload.FitsInMessage(stream);
 
         var blobRef = blobName != null ? BlobRef.Get(blobName) : BlobRef.Create();
-        stream.Position = 0;
         await container.GetBlobClient(blobRef.BlobName).UploadAsync(stream, overwrite: true, ct);
-
-        return new Payload(JsonSerializer.SerializeToUtf8Bytes(blobRef), true);
+        return Payload.OffloadedToBlob(blobRef);
     }
 
     public async Task<QueueMessage<T>[]> Receive(int maxMessages = MaxMessagesReceive, TimeSpan? visibilityTimeout = null,
@@ -151,8 +150,7 @@ public async Task Dequarantine(CancellationToken ct = default)
     public async Task QuarantineData(T item, CancellationToken ct)
     {
         var payload = await SerializeAndOffloadIfBig(item, ct: ct);
-
-        await quarantineQueue.SendMessageAsync(new BinaryData(payload.Data), cancellationToken: ct);
+        await quarantineQueue.SendMessageAsync(payload.Data, cancellationToken: ct);
     }
 
     async Task<QueueMessage<T>?> ToQueueMessage(QueueMessage m, CancellationToken ct, bool fromQuarantine = false)
@@ -207,13 +205,6 @@ static bool IsBlobRef(BinaryData data, out BlobRef? o)
         }
     }
 
-    record BlobRef([property: JsonPropertyName("__MSQ_QUEUE_BLOBNAME__")] string BlobName)
-    {
-        public static BlobRef Get(string blobName) => new(blobName);
-        public static BlobRef Create() => new(FileName());
-        static string FileName() => $"{DateTime.UtcNow:yyyy-MM-dd}/{DateTime.UtcNow:s}{Guid.NewGuid():N}.json.gzip";
-    }
-
     public async Task Init() => await Task.WhenAll(queue.CreateIfNotExistsAsync(), quarantineQueue.CreateIfNotExistsAsync(), container.CreateIfNotExistsAsync());
 
     public async Task Delete(bool deleteBlobs = false)
@@ -233,9 +224,24 @@ public MessageQueue<T> WithLogger(ILogger queueLogger)
         logger = queueLogger;
         return this;
     }
+
+    record BlobRef([property: JsonPropertyName("__MSQ_QUEUE_BLOBNAME__")] string BlobName)
+    {
+        public static BlobRef Get(string blobName) => new(blobName);
+        public static BlobRef Create() => new(FileName());
+        static string FileName() => $"{DateTime.UtcNow:yyyy-MM-dd}/{DateTime.UtcNow:s}{Guid.NewGuid():N}.json.gzip";
+    }
+
+    record Payload(BinaryData Data, bool Offloaded)
+    {
+        public static Payload FitsInMessage(MemoryStream stream) =>
+            new(BinaryData.FromStream(stream), false);
+
+        public static Payload OffloadedToBlob(BlobRef blobRef) =>
+            new(BinaryData.FromObjectAsJson(blobRef), true);
+    }
 }
 
 public record QueueMessage<T>(T Item, MessageId MessageId, QueueMessageMetadata Metadata);
 public record QueueMessageMetadata(DateTimeOffset VisibilityTime, DateTimeOffset InsertedOn, long DequeueCount = 0);
 public record MessageId(string Id, string PopReceipt, string? BlobName);
-public record Payload(ReadOnlyMemory<byte> Data, bool Offloaded);