Make async query execution compatible with WASM by gathogojr · Pull Request #3474 · OData/odata.net

gathogojr · 2026-01-12T07:17:47Z

Issues

This pull request fixes #3452.

Description

This PR introduces a modernized, end‑to‑end asynchronous request/response path for OData Client that removes synchronous waits from async flows, restores Blazor WASM compatibility, and improves cancellation/timeout behavior—without breaking existing public APIs. It lays the groundwork for deprecating APM (Begin/End) in the next major release.

Motivation

Customer regression in 8.4.3 (WASM): Blazor WebAssembly disallows blocking waits; certain internal paths performed Task.Wait() after SendAsync, surfacing “Cannot wait on monitors on this runtime.”
Underlying cause: Introducing HttpCompletionOption.ResponseHeadersRead allowed faster cancellation but exposed latent blocking in downstream conversion that synchronously waited on ReadAsStreamAsync().
Architectural debt: Async APIs were often thin wrappers over APM (Begin/End + FromAsync), not truly async/await, making timeouts and cancellation brittle across runtimes.

Design Overview

New async-native pathway

Introduce and route async callers through a unified, non-blocking pipeline:

DataServiceContext.GetResponseAsync
 → ODataRequestMessageWrapper.GetResponseAsync
   → DataServiceClientRequestMessage.GetResponseAsync
     → HttpClientRequestMessage.GetResponseAsync
        → SendInternalAsync(HttpCompletionOption.ResponseHeadersRead, CTs)
        → ConvertHttpWebResponseAsync

This path never blocks and honours cancellation via linked tokens (abort + per‑request timeout + external token).

Cancellation/Timeout

All sends use a linked CancellationToken that merges:

Abort token (from Abort()),
Per-request timeout token,
Optional external token.
This yields prompt, deterministic cancellation across stages (pre‑content, headers, body).

Key Code Changes

HTTP transport (HttpClientRequestMessage)

Add async response conversion to avoid sync waits: ConvertHttpWebResponseAsync(HttpResponseMessage) and GetResponseAsync(CancellationToken).
Rework CreateSendTask(CancellationToken) to build a linked token source and to send with ResponseHeadersRead for earlier cancellation; apply cached content headers prior to send.

Note: The previous implementation synchronously waited while reading the content stream during conversion, which is invalid on WASM; the new async conversion eliminates that path.

Request/response surface (selected)

Async entry points throughout the stack now flow through the new path:
- ODataRequestMessageWrapper.GetResponseAsync(CancellationToken)
- RequestInfo.GetResponseAsync(ODataRequestMessageWrapper, bool, CancellationToken)
- Async query/request orchestrators (QueryResult.ExecuteQueryAsync, GetReadStreamResult.ExecuteQueryAsync, etc.) use the new async response and streaming logic.

High-level APIs

DataServiceQuery<T>.ExecuteAsync(...), DataServiceActionQuerySingle<T>.GetValueAsync(...), and other public async APIs continue to exist but now route through the modernized path under the hood.

API Surface (additions / changes)

No public breaking changes in this PR. APM (Begin/End) remains for compatibility; async paths are modernized internally.

Key new / updated async members (representative):

Transport / messaging
- DataServiceClientRequestMessage.GetResponseAsync(CancellationToken) (virtual)
- HttpClientRequestMessage.GetResponseAsync(CancellationToken) / CreateSendTask(CancellationToken) / ConvertHttpWebResponseAsync(...)
- ODataRequestMessageWrapper.GetResponseAsync(CancellationToken) (internal)
- RequestInfo.GetResponseAsync(...) (internal)
Query & streaming
- QueryResult.ExecuteQueryAsync(CancellationToken) / ProcessResponseStreamAsync(CancellationToken) (internal)
- GetReadStreamResult.ExecuteQueryAsync(CancellationToken) (internal)
Save / batch flows
- SaveResult.CreateNextChangeAsync(CancellationToken)
- BatchSaveResult.BatchRequestAsync(CancellationToken)
- DeepInsertSaveResult.DeepInsertRequestAsync<T>(T, CancellationToken)
- BulkUpdateSaveResult.BulkUpdateRequestAsync<T>(CancellationToken, T[])
- DataServiceContext.*Async methods

Checklist (Uncheck if it is not completed)

Test cases added
Build and test with one-click build and test script passed

Additional work necessary

If documentation update is needed, please add "Docs Needed" label to the issue and provide details about the required document change in the issue.

xuzhg · 2026-01-13T18:47:05Z

src/Microsoft.OData.Client/BatchSaveResult.cs

+                {
+                    InvalidOperationException exception = WebUtil.GetHttpWebResponse(ex, ref this.batchResponseMessage);
+
+                    // For non-async batch requests we rethrow the WebException.  This is shipped behavior.


Can you also update the comments to make sure it's still readable later?

xuzhg · 2026-01-13T18:47:15Z

src/Microsoft.OData.Client/BatchSaveResult.cs

+                    if (this.batchResponseMessage != null)
+                    {
+                        // For non-async batch requests we call the test hook to get the response stream but we cannot consume it
+                        // because we rethrow what we caught and the customer need to be able to read the response stream from the WebException.


Can you also update the comments to make sure it's still readable later?

xuzhg · 2026-01-13T18:48:33Z

src/Microsoft.OData.Client/BatchSaveResult.cs

+        /// </summary>
+        /// <param name="cancellationToken">Optional cancellation token.</param>
+        /// <returns>A task that represents the asynchronous batch request operation.</returns>
+        internal async Task BatchRequestAsync(CancellationToken cancellationToken = default)


Task

Can we use ValueTask?

xuzhg · 2026-01-13T18:50:24Z

src/Microsoft.OData.Client/DataServiceQueryOfT.cs

+                .ConfigureAwait(false);
+        }
+
+        // TODO: In future releases, expose this method as public GetAllPagesAsync to support IAsyncEnumerable


why do we wait for future release since we support it

@xuzhg Because in the current version, there's already a GetAllPagesAsync method that returns IEnumerable<T>. We'd switch that with IAsyncEnumerable<T> in a major release because it'd be a breaking change

xuzhg · 2026-01-13T19:08:47Z

src/Microsoft.OData.Client/QueryResult.cs

+                this.outputResponseStream = null;
+            }
+            else if (copy.Position < copy.Length)
+            {   // In Silverlight, generally 3 bytes less than advertised by ContentLength are read


Silverlight

do we still to mean about 'SilverLight'?

xuzhg · 2026-01-13T19:10:52Z

src/Microsoft.OData.Client/WebUtil.cs

            if (buffer == null)
            {
-                refBuffer = buffer = new byte[1000];
+                refBuffer = buffer = new byte[1000]; // Why does this use 1000 instead of DefaultBufferSizeForStreamCopy?


Did you check the history to see "why"?

xuzhg

gathogojr force-pushed the fix/3452-wasm-compatibility branch from b0028e9 to 0e4adf3 Compare January 12, 2026 07:45

xuzhg reviewed Jan 13, 2026

View reviewed changes

xuzhg previously approved these changes Jan 13, 2026

View reviewed changes

gathogojr force-pushed the fix/3452-wasm-compatibility branch from 0e4adf3 to 88a2eb8 Compare January 19, 2026 13:30

gathogojr dismissed xuzhg’s stale review via 60aff18 January 21, 2026 18:33

gathogojr force-pushed the fix/3452-wasm-compatibility branch 2 times, most recently from 60aff18 to 240a800 Compare January 22, 2026 05:46

Make async query execution compatible with WASM

28f1005

gathogojr force-pushed the fix/3452-wasm-compatibility branch from 240a800 to 28f1005 Compare January 23, 2026 06:41

Add OData Client WebAssembly Sample projects

fb311b7

gathogojr force-pushed the fix/3452-wasm-compatibility branch from 2a3a08e to fb311b7 Compare January 26, 2026 20:08

Provide feedback

Saved searches

Use saved searches to filter your results more quickly

Make async query execution compatible with WASM#3474

Make async query execution compatible with WASM#3474
gathogojr wants to merge 2 commits intoOData:mainfrom
gathogojr:fix/3452-wasm-compatibility

gathogojr commented Jan 12, 2026

Uh oh!

xuzhg Jan 13, 2026

Uh oh!

xuzhg Jan 13, 2026

Uh oh!

xuzhg Jan 13, 2026

Uh oh!

xuzhg Jan 13, 2026

Uh oh!

gathogojr Jan 19, 2026

Uh oh!

xuzhg Jan 13, 2026

Uh oh!

xuzhg Jan 13, 2026

Uh oh!

xuzhg left a comment

Uh oh!

Reviewers

Assignees

Labels

Projects

Milestone

Development

Uh oh!

2 participants

Conversation

gathogojr commented Jan 12, 2026

Issues

Description

Motivation

Design Overview

New async-native pathway

Cancellation/Timeout

Key Code Changes

HTTP transport (HttpClientRequestMessage)

Request/response surface (selected)

High-level APIs

API Surface (additions / changes)

Checklist (Uncheck if it is not completed)

Additional work necessary

Uh oh!

xuzhg Jan 13, 2026

Choose a reason for hiding this comment

Uh oh!

xuzhg Jan 13, 2026

Choose a reason for hiding this comment

Uh oh!

xuzhg Jan 13, 2026

Choose a reason for hiding this comment

Uh oh!

xuzhg Jan 13, 2026

Choose a reason for hiding this comment

Uh oh!

gathogojr Jan 19, 2026

Choose a reason for hiding this comment

Uh oh!

xuzhg Jan 13, 2026

Choose a reason for hiding this comment

Uh oh!

xuzhg Jan 13, 2026

Choose a reason for hiding this comment

Uh oh!

xuzhg left a comment

Choose a reason for hiding this comment

Uh oh!

Reviewers

Assignees

Labels

Projects

Milestone

Development

Uh oh!

2 participants