macOS: fix FX Pak Pro dropping out during play (desync/timeout fixes + disable App Nap)

.github/workflows/release.yml

@@ -12,14 +12,14 @@ jobs:
     runs-on: ubuntu-latest
     steps:
       - name: Set up Go
-        uses: actions/setup-go@v5
+        uses: actions/setup-go@v7
         with:
           go-version: '^1.23.0'
 
       - name: Set up linux dependencies
         run: sudo apt-get update && sudo apt-get install -y gcc
 
-      - uses: actions/checkout@v4
+      - uses: actions/checkout@v7
         with:
           fetch-depth: 0
 
@@ -48,11 +48,6 @@ jobs:
             goarch: "386"
             suffix: zip
             name: win-x86
-          - os: windows-latest
-            goos: windows
-            goarch: arm
-            suffix: zip
-            name: win-arm
           - os: windows-latest
             goos: windows
             goarch: arm64
@@ -63,11 +58,11 @@ jobs:
 
     steps:
       - name: Inject slug/short variables
-        uses: rlespinasse/github-slug-action@v4
+        uses: rlespinasse/github-slug-action@v5
 
       - name: Set up Go
         if: ${{ matrix.goos != 'windows' || matrix.os-variant != '7' }}
-        uses: actions/setup-go@v5
+        uses: actions/setup-go@v7
         with:
           go-version: '^1.23.0'
 
@@ -80,7 +75,7 @@ jobs:
 
       - run: echo "basename=sni-${{env.GITHUB_REF_SLUG}}-${{matrix.goos}}${{matrix.os-variant}}-${{matrix.goarch}}${{matrix.alt}}" | Out-File -FilePath $env:GITHUB_ENV -Encoding utf8 -Append
 
-      - uses: actions/checkout@v4
+      - uses: actions/checkout@v7
         name: Checkout
         with:
           fetch-depth: 0
@@ -130,7 +125,7 @@ jobs:
         run: 7z x -o"${{env.basename}}" "${{ runner.temp }}/${{ matrix.snfm }}"
 
       - name: Upload artifact
-        uses: actions/upload-artifact@v4
+        uses: actions/upload-artifact@v7
         with:
           name: ${{env.basename}}
           path: ${{env.basename}}/
@@ -163,16 +158,16 @@ jobs:
 
     steps:
       - name: Inject slug/short variables
-        uses: rlespinasse/github-slug-action@v4
+        uses: rlespinasse/github-slug-action@v5
 
       - name: Set up Go
-        uses: actions/setup-go@v5
+        uses: actions/setup-go@v7
         with:
           go-version: '^1.23.0'
 
       - run: echo "basename=sni-${{env.GITHUB_REF_SLUG}}-darwin-universal${{matrix.alt}}" >> $GITHUB_ENV
 
-      - uses: actions/checkout@v4
+      - uses: actions/checkout@v7
         name: Checkout
         with:
           fetch-depth: 0
@@ -218,7 +213,7 @@ jobs:
         run: 7z x -o"${{env.basename}}" "${{ runner.temp }}/${{ matrix.snfm }}"
 
       - name: Upload artifact
-        uses: actions/upload-artifact@v4
+        uses: actions/upload-artifact@v7
         with:
           name: ${{env.basename}}
           path: ${{env.basename}}/
@@ -282,10 +277,10 @@ jobs:
 
     steps:
       - name: Inject slug/short variables
-        uses: rlespinasse/github-slug-action@v4
+        uses: rlespinasse/github-slug-action@v5
 
       - name: Set up Go
-        uses: actions/setup-go@v5
+        uses: actions/setup-go@v7
         with:
           go-version: '^1.23.0'
 
@@ -294,7 +289,7 @@ jobs:
 
       - run: echo "basename=sni-${{env.GITHUB_REF_SLUG}}-${{matrix.goos}}${{matrix.os-variant}}-${{matrix.goarch}}${{matrix.alt}}" >> $GITHUB_ENV
 
-      - uses: actions/checkout@v4
+      - uses: actions/checkout@v7
         name: Checkout
         with:
           fetch-depth: 0
@@ -336,7 +331,7 @@ jobs:
         run: 7z x -o"${{env.basename}}" "${{ runner.temp }}/${{ matrix.snfm }}"
 
       - name: Upload artifact
-        uses: actions/upload-artifact@v4
+        uses: actions/upload-artifact@v7
         with:
           name: ${{env.basename}}
           path: ${{env.basename}}/
@@ -361,10 +356,10 @@ jobs:
     name: manylinux_2_28
     steps:
       - name: Inject slug/short variables
-        uses: rlespinasse/github-slug-action@v4
+        uses: rlespinasse/github-slug-action@v5
 
       - name: Set up Go
-        uses: actions/setup-go@v5
+        uses: actions/setup-go@v7
         with:
           go-version: '^1.23.0'
 
@@ -375,7 +370,7 @@ jobs:
 
       - run: echo "basename=sni-${{env.GITHUB_REF_SLUG}}-manylinux_2_28-amd64" >> $GITHUB_ENV
 
-      - uses: actions/checkout@v4
+      - uses: actions/checkout@v7
         name: Checkout
         with:
           fetch-depth: 0
@@ -414,7 +409,7 @@ jobs:
           tar cJf ${{env.basename}}.tar.xz ${{env.basename}}/
 
       - name: Upload artifact
-        uses: actions/upload-artifact@v4
+        uses: actions/upload-artifact@v7
         with:
           name: ${{env.basename}}.tar.xz
           path: ${{github.workspace}}/${{env.basename}}.tar.xz

cmd/sni/config/config.go

@@ -50,6 +50,27 @@ var (
 		"usb2snes_listen_addrs": "0.0.0.0:23074",
 		"fxpakpro_disable":      false,
 
+		// How long the fxpakpro driver waits on a device that has gone quiet or
+		// stopped accepting data. The firmware does its FAT work inside the USB
+		// interrupt handler, so a cluster allocation on a large, full, fragmented
+		// card can stall for seconds before it can answer; raise these if you see
+		// spurious timeouts on such a card.
+		"fxpakpro_read_timeout":  "15s",
+		"fxpakpro_write_timeout": "15s",
+		// Whether a caller's context deadline or cancellation aborts I/O already
+		// in flight to the device. With this off, a request that has already
+		// started talking to the fxpakpro runs to completion (bounded by the two
+		// timeouts above) rather than being cut short mid-transfer by an
+		// impatient client.
+		"fxpakpro_honor_caller_deadline": true,
+		// Optional pause after each 512-byte chunk written during a transfer.
+		// Zero, the default, writes as fast as the device accepts data. This
+		// exists to test whether host write pacing affects reliability: setting
+		// SNI_DEBUG=1 slows transfers dramatically (a hex dump per chunk to a
+		// file and the console) and has been reported to make failing transfers
+		// succeed, so this isolates the timing from the logging.
+		"fxpakpro_chunk_delay": "0s",
+
 		"retroarch_disable":    false,
 		"retroarch_hosts":      "localhost:55355",
 		"retroarch_detect_log": false,
@@ -64,8 +85,8 @@ var (
 		"emunw_disable":    false,
 		"emunw_detect_log": false,
 
-		"proxy_disable":       false,
-		"proxy_backend_host":  "",
+		"proxy_disable":      false,
+		"proxy_backend_host": "",
 	}
 	nwaConfigs = map[string]any{
 		"nwa_port_range":        NwaDefaultPort,
@@ -91,7 +112,7 @@ func InitDir() {
 		Dir = filepath.Join(Dir, ".sni")
 
 		// Follow XDG Base Directory Specification
-		if _, err := os.Stat(Dir); err != nil {		
+		if _, err := os.Stat(Dir); err != nil {
 			var xdgConfig = os.Getenv("XDG_CONFIG_HOME")
 			if xdgConfig == "" {
 				homeDir, _ := os.UserHomeDir()

cmd/sni/main.go

@@ -10,6 +10,7 @@ import (
 	"sni/cmd/sni/appversion"
 	"sni/cmd/sni/config"
 	"sni/cmd/sni/logging"
+	"sni/cmd/sni/power"
 	"sni/cmd/sni/tray"
 	"sni/devices/snes/drivers/emunwa"
 	"sni/devices/snes/drivers/fxpakpro"
@@ -39,6 +40,11 @@ func main() {
 	// keep the initial goroutine on this thread for GUI threading purposes
 	runtime.LockOSThread()
 
+	// on macOS, keep this window-less tray process out of App Nap so it keeps
+	// servicing USB devices promptly instead of being throttled in the
+	// background (no-op on other platforms):
+	power.DisableAppNap("SNI maintains real-time communication with SNES devices")
+
 	// make the version info public in the appversion package because the main package cannot be imported:
 	appversion.Init(
 		version,

cmd/sni/power/appnap_darwin.go

@@ -0,0 +1,43 @@
+//go:build darwin
+
+package power
+
+/*
+#cgo darwin CFLAGS: -x objective-c -fobjc-arc
+#cgo darwin LDFLAGS: -framework Foundation
+#include <stdlib.h>
+#import <Foundation/Foundation.h>
+
+// beginActivity takes a process-level activity assertion and retains the
+// returned token so the assertion lives for the entire lifetime of the
+// process. The token is intentionally never released; the OS drops it when
+// the process exits.
+static void beginActivity(const char *reason) {
+    NSString *r = [NSString stringWithUTF8String:reason];
+    // NSActivityUserInitiatedAllowingIdleSystemSleep disables App Nap so this
+    // background, window-less process keeps servicing USB promptly, while still
+    // allowing the machine to sleep normally when the user walks away.
+    NSActivityOptions opts = NSActivityUserInitiatedAllowingIdleSystemSleep;
+    id token = [[NSProcessInfo processInfo] beginActivityWithOptions:opts reason:r];
+    CFBridgingRetain(token);
+}
+*/
+import "C"
+
+import "unsafe"
+
+// DisableAppNap asks macOS to keep this process out of App Nap for its entire
+// lifetime.
+//
+// App Nap throttles and coalesces the timers and threads of a background,
+// window-less application. SNI presents only a status-bar (tray) icon with no
+// window, so macOS is free to nap it while a game is in the foreground. A
+// napped SNI stops servicing the FX Pak Pro's USB serial stream promptly, which
+// makes the device appear to stop responding (reads return zero bytes, writes
+// stall) until SNI is restarted. Holding a user-initiated activity assertion
+// prevents that.
+func DisableAppNap(reason string) {
+	cReason := C.CString(reason)
+	defer C.free(unsafe.Pointer(cReason))
+	C.beginActivity(cReason)
+}

cmd/sni/power/appnap_other.go

@@ -0,0 +1,6 @@
+//go:build !darwin
+
+package power
+
+// DisableAppNap is a no-op on platforms that do not have macOS App Nap.
+func DisableAppNap(reason string) {}