MtClient/MtApi5: async command API with request pipelining#310

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biohazardxxx wants to merge 4 commits into

vdemydiuk:devfrom

biohazardxxx:feat/mtclient-async-commands

biohazardxxx commented Jul 6, 2026

Summary

The RPC core already supports multiple in-flight commands (responses are correlated by commandId, and the expert drains its whole command queue per wake-up), but the public API is strictly synchronous — one blocked thread per outstanding command. This PR adds a first-class async path so callers can pipeline requests:

MtClient: CommandTask gains a TaskCompletionSource (created with RunContinuationsAsynchronously — continuations never run inline on the receive thread); new Task<string?> SendCommandAsync(...) mirrors SendCommand's registration, locking, and timeout semantics exactly. Purely additive — MT4's MtApiClient compiles untouched (verified).
MtApi5: private SendCommandAsync<T> mirrors SendCommand<T> exception semantics; public async variants for the read-heavy hot set: PositionsTotalAsync, OrdersTotalAsync, AccountInfoDouble/IntegerAsync, SymbolInfoTickAsync, SymbolInfoDouble/IntegerAsync, CopyRatesAsync (3 overloads, returning Task<MqlRates[]> directly instead of out params), CopyTicksAsync, TimeCurrentAsync.
Test client: AsyncPipelineDemo action comparing 20 sequential sync calls vs 20 concurrent async calls.

No async variants for trade operations by design — OrderSendAsync already exists as a synchronous wrapper of MQL5's OrderSendAsync command and a Task-returning overload of that name would be a foot-gun.

Implementation notes

Timeout semantics mirror sync exactly, including the benign race where a response arriving between timeout expiry and lock acquisition is still returned.
All library awaits use ConfigureAwait(false); no async void in library code.
CopyRatesAsync returns [] (never null) on a null response, matching the observable behavior of the sync overloads (review finding, fixed in c236352).

Testing

All four projects build clean (MtClient, MtApi5, MtApi — proving the MT4 surface untouched — and the test client).
Adversarial review traced deadlock/lock-ordering, task-leak, unobserved-exception, and semantics-parity concerns — no confirmed defects beyond the CopyRatesAsync null/empty drift, which is fixed.
Runtime-verified against a live MT5 terminal (build 5830):
- Correctness: PositionsTotalAsync/TimeCurrentAsync results equal their sync counterparts.
- Pipelining: 20 concurrent async commands complete in 102 ms vs 1997 ms for 20 sequential sync calls against an expert on a 100 ms polling timer (x19.6) — all 20 served in a single wake-up, as designed. Against a nudge-responsive expert: 5 ms vs 27 ms (x5.4).

🤖 Generated with Claude Code

biohazardxxx and others added 4 commits

July 6, 2026 12:53


          feat(MtClient): add async command path to MtRpcClient

4bb8194

Add SendCommandAsync alongside the sync SendCommand. CommandTask now
completes a TaskCompletionSource (created with
RunContinuationsAsynchronously so awaiter continuations never run
inline on the receive thread) in addition to the existing
EventWaitHandle. Timeout semantics mirror the sync path: on timeout
the current response value (null if none arrived) is returned and the
task entry is removed. No existing signature or behavior changed.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>


          feat(MtApi5): add async variants for read-heavy hot-set commands

86e8e8e

Add a private SendCommandAsync<T> mirroring SendCommand<T> (same
response parsing and ExecutionException semantics) and public async
variants: PositionsTotalAsync, OrdersTotalAsync, AccountInfoDoubleAsync,
AccountInfoIntegerAsync, SymbolInfoTickAsync, SymbolInfoDoubleAsync,
SymbolInfoIntegerAsync, CopyRatesAsync (x3 overloads returning the
array directly instead of out params), CopyTicksAsync, TimeCurrentAsync.

Multiple in-flight commands are pipelined and typically served in a
single expert wake-up. Trade operations are intentionally excluded:
OrderSendAsync already exists as a sync wrapper of MQL's
OrderSendAsync command and must not be shadowed.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>


          feat(MtApi5TestClient): add AsyncPipelineDemo latency comparison

56ef3ef

New button on the Time and Date tab runs 20 sequential sync calls
(PositionsTotal/TimeCurrent alternating) followed by the same 20 calls
concurrently via Task.WhenAll on the async variants, and logs both
wall-clock times to demonstrate command pipelining.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>


          MtApi5: CopyRatesAsync returns empty array on null response

c236352

Matches the observable behavior of the sync CopyRates overloads
(ratesArray is never null) and the CopyTicksAsync/CopyTicks parity.
Review finding.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

biohazardxxx mentioned this pull request

MQL5: add timer-based command polling for live trading #295

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4 tasks

hosseinkhojany pushed a commit to hosseinkhojany/mtapi that referenced this pull request


          Merge PR vdemydiuk#310 from vdemydiuk/mtapi: async command API with r…

b99e8f3

…equest pipelining

# Conflicts:
#	TestClients/MtApi5TestClient/MainWindow.xaml
#	TestClients/MtApi5TestClient/ViewModel.cs

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