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Android native: tighten Oboe build, fix getLastError race, cut audio-thread syscalls #208

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Merged
winnerspiros merged 2 commits into from
Apr 19, 2026
Merged

Android native: tighten Oboe build, fix getLastError race, cut audio-thread syscalls #208

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3b32acd
Fix Android native build: oboe::AllowedCapturePolicy::None
Copilot Apr 19, 2026
7e3abe3
Native Android perf/latency tightening
Copilot Apr 19, 2026
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22 changes: 19 additions & 3 deletions osu.Android/Native/CMakeLists.txt
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Original file line number Diff line number Diff line change
Expand Up @@ -22,24 +22,40 @@ set(CMAKE_SHARED_LINKER_FLAGS_RELEASE "-Wl,--gc-sections -Wl,-z,max-page-size=16
# features (our bridge outputs silence for latency measurement only).
# This reduces the Oboe portion of the binary by ~50%.
set(OBOE_ENABLE_FLOWGRAPH OFF CACHE BOOL "Disable Oboe flowgraph to reduce binary size")
# Skip Oboe's tests/examples — we never ship them. Avoids pulling googletest
# and shaves several seconds off the cold CMake configure/build.
set(BUILD_TESTING OFF CACHE BOOL "Disable Oboe tests" FORCE)
set(OBOE_BUILD_TESTS OFF CACHE BOOL "Disable Oboe tests" FORCE)
set(OBOE_BUILD_EXAMPLES OFF CACHE BOOL "Disable Oboe examples" FORCE)
set(OBOE_BUILD_DOCS OFF CACHE BOOL "Disable Oboe docs" FORCE)

# Download and build Oboe main branch from source to ensure we have the latest
# features and fixes (ADPF performance hints, workload management, spatialization,
# API 36 compatibility) regardless of the build environment.
# main is preferred over pinned tags because Oboe releases infrequently (~yearly)
# and the main branch accumulates significant latency-critical improvements between tags.
# GIT_SHALLOW TRUE: only fetch the tip of main (no history) — significantly faster CI checkout.
include(FetchContent)
FetchContent_Declare(oboe
GIT_REPOSITORY https://github.com/google/oboe.git
GIT_TAG main
GIT_SHALLOW TRUE
)
FetchContent_MakeAvailable(oboe)

# Patch Oboe's deprecated -Ofast flag to avoid build warnings/errors
# and ensure we use the same optimized flags as the rest of the project.
# Patch Oboe's compile options:
# 1. Replace deprecated `-Ofast` with `-O3` — `-Ofast` was removed in Clang 21
# and emits warnings on newer NDKs.
# 2. Strip `-ffast-math` from Oboe's compile options. In a callback that only
# does memset/store it is harmless functionally, but it injects libm
# `__FINITE_MATH_ONLY__` symbol versions that can break linkage against the
# system libm in rare NDK combos. Our own bridge keeps `-ffast-math` (see
# CMAKE_CXX_FLAGS_RELEASE above) because we link only against libc/log/Vulkan.
get_target_property(OBOE_OPTIONS oboe COMPILE_OPTIONS)
if(OBOE_OPTIONS)
string(REPLACE "-Ofast" "-O3;-ffast-math" OBOE_OPTIONS "${OBOE_OPTIONS}")
list(REMOVE_ITEM OBOE_OPTIONS "-Ofast")
list(REMOVE_ITEM OBOE_OPTIONS "-ffast-math")
list(APPEND OBOE_OPTIONS "-O3")
set_target_properties(oboe PROPERTIES COMPILE_OPTIONS "${OBOE_OPTIONS}")
endif()

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28 changes: 22 additions & 6 deletions osu.Android/Native/oboe_bridge.cpp
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Expand Up @@ -114,7 +114,7 @@ bool OboeBridge::open(int32_t sampleRate) {
// Audio is pre-mixed by BASS — tell Android not to spatialize it again.
->setIsContentSpatialized(true)
// Prevent other apps from capturing our audio stream (competitive integrity).
->setAllowedCapturePolicy(oboe::AllowedCapturePolicy::AllowNone)
->setAllowedCapturePolicy(oboe::AllowedCapturePolicy::None)
// Use shared_ptr overload (non-deprecated) for data callback.
->setDataCallback(stabilizedCallback_)
// Non-owning shared_ptr for error callback — OboeBridge outlives the stream.
Expand Down Expand Up @@ -250,9 +250,9 @@ void OboeBridge::setProvider(OboeAudioProvider provider) {
provider_.store(provider, std::memory_order_release);
}

const char* OboeBridge::getLastError() const {
std::string OboeBridge::getLastError() const {
std::lock_guard<std::mutex> lock(errorLock_);
return lastError_.empty() ? nullptr : lastError_.c_str();
return lastError_;
}

oboe::DataCallbackResult OboeBridge::onAudioReady(
Expand Down Expand Up @@ -283,14 +283,19 @@ oboe::DataCallbackResult OboeBridge::onAudioReady(

uint32_t count = callbackCount_.fetch_add(1, std::memory_order_relaxed);

// LatencyTuner once every 128 callbacks (~1.5s @ 192 burst, 48 kHz).

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The new comment says “~1.5s @ 192 burst, 48 kHz”, but 128 callbacks * 192 frames / 48kHz is ~0.51s (and the callback frame count may not even be fixed since framesPerDataCallback is unspecified). Please correct or soften the timing estimate to avoid misleading future readers.

Suggested change
// LatencyTuner once every 128 callbacks (~1.5s @ 192 burst, 48 kHz).
// Run the LatencyTuner once every 128 callbacks. The wall-clock interval
// depends on the callback frame count and sample rate (for example, at
// 192 frames/callback and 48 kHz this is about 0.5s).

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// updateLatency() issues an AAudio syscall, so throttle it further to every
// 256 callbacks — Tab still sees stable values, but we cut audio-thread
// syscall pressure in half.
if ((count & 127) == 0) {
updateLatency();

// Dynamically tune the buffer size to the lowest stable value.
if (tuner_) {
tuner_->tune();
}

if ((count & 255) == 0)
updateLatency();

// Attempt to set CPU affinity to high-performance cores.
// We do this inside the audio callback to ensure we target the AAudio thread.
// Uses sysfs-based topology detection for accurate big-core identification
Expand Down Expand Up @@ -478,7 +483,15 @@ OSU_EXPORT void nOboeSetProvider(intptr_t ptr, OboeAudioProvider provider) {

OSU_EXPORT const char* nOboeGetLastErrorMessage(intptr_t ptr) {
auto* bridge = reinterpret_cast<OboeBridge*>(ptr);
return bridge ? bridge->getLastError() : nullptr;
if (!bridge) return nullptr;

// Hold a thread_local snapshot so the pointer we hand back to managed code
// remains valid for the duration of the P/Invoke marshalling step, even if
// another thread (Oboe error callback) overwrites `lastError_` immediately
// after we return. Each managed thread gets its own buffer.
thread_local std::string snapshot;
snapshot = bridge->getLastError();
return snapshot.empty() ? nullptr : snapshot.c_str();
}

} // extern "C"
Expand Down Expand Up @@ -512,6 +525,9 @@ OSU_EXPORT int nGetBigCoreMask() {
}

#include <android/performance_hint.h>
// Explicit dependency for gettid() used in nADPFCreateSession below — do not
// rely on transitive includes from Oboe / NDK headers, which may change.
#include <unistd.h>
Comment on lines +528 to +530

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<unistd.h> is already included at the top of this file, so the new mid-file #include <unistd.h> is redundant and the “don’t rely on transitive includes” comment is now misleading. Consider removing the duplicate include (and ideally keeping all includes in one place).

Suggested change
// Explicit dependency for gettid() used in nADPFCreateSession below — do not
// rely on transitive includes from Oboe / NDK headers, which may change.
#include <unistd.h>

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extern "C" {
OSU_EXPORT intptr_t nADPFCreateSession(int64_t targetDurationNanos) {
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6 changes: 5 additions & 1 deletion osu.Android/Native/oboe_bridge.h
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Expand Up @@ -33,7 +33,11 @@ class OboeBridge : public oboe::AudioStreamCallback {
bool isAAudio() const;
bool isMMap() const;
void setProvider(OboeAudioProvider provider);
const char* getLastError() const;
/// Returns a copy of the most recent error message under lock. We return
/// by value (not a pointer to internal storage) so callers can't observe a
/// torn or freed `std::string` if another thread mutates `lastError_`
/// concurrently (Oboe error callbacks fire from an internal thread).
std::string getLastError() const;
Comment on lines +36 to +40

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oboe_bridge.h uses std::string in the public API (getLastError()) but the header doesn’t explicitly include <string>. It currently works only if a transitive include happens to pull it in; please add #include <string> to make the header self-contained.

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// oboe::AudioStreamCallback
oboe::DataCallbackResult onAudioReady(
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