| 1 | //go:build windows |
| 2 | |
| 3 | package main |
| 4 | |
| 5 | import ( |
| 6 | "os" |
| 7 | "sync" |
| 8 | "syscall" |
| 9 | "time" |
| 10 | "unsafe" |
| 11 | |
| 12 | "golang.org/x/sys/windows" |
| 13 | ) |
| 14 | |
| 15 | const ( |
| 16 | wmNull = 0x0000 |
| 17 | smtoBlock = 0x0001 |
| 18 | smtoAbortIfHung = 0x0002 |
| 19 | ) |
| 20 | |
| 21 | var ( |
| 22 | user32DLL = windows.NewLazySystemDLL("user32.dll") |
| 23 | enumWindowsProc = user32DLL.NewProc("EnumWindows") |
| 24 | getClassNameProc = user32DLL.NewProc("GetClassNameW") |
| 25 | getWindowThreadProcessProc = user32DLL.NewProc("GetWindowThreadProcessId") |
| 26 | sendMessageTimeoutProc = user32DLL.NewProc("SendMessageTimeoutW") |
| 27 | windowsHeartbeatMu sync.Mutex |
| 28 | windowsHeartbeatStop chan struct{} |
| 29 | enumWindowsMu sync.Mutex |
| 30 | enumWindowsPID uint32 |
| 31 | enumWindowsFound uintptr |
| 32 | enumWindowsCallback = syscall.NewCallback(enumCurrentProcessTopLevelWindow) |
| 33 | ) |
| 34 | |
| 35 | func mainThreadWatchdogSupported() bool { return true } |
| 36 | |
| 37 | func startNativeMainThreadHeartbeat(intervalMS uint64) { |
| 38 | windowsHeartbeatMu.Lock() |
| 39 | if windowsHeartbeatStop != nil { |
| 40 | windowsHeartbeatMu.Unlock() |
| 41 | return |
| 42 | } |
| 43 | stop := make(chan struct{}) |
| 44 | windowsHeartbeatStop = stop |
| 45 | windowsHeartbeatMu.Unlock() |
| 46 | |
| 47 | go func() { |
| 48 | interval := time.Duration(intervalMS) * time.Millisecond |
| 49 | if interval <= 0 { |
| 50 | interval = time.Second |
| 51 | } |
| 52 | ticker := time.NewTicker(interval) |
| 53 | defer ticker.Stop() |
| 54 | for { |
| 55 | select { |
| 56 | case <-stop: |
| 57 | return |
| 58 | case now := <-ticker.C: |
| 59 | hwnd := currentProcessTopLevelWindow() |
| 60 | // Window creation can lag OnStartup. Treat absence as |
| 61 | // inconclusive instead of manufacturing a startup hang. |
| 62 | if hwnd == 0 || windowMessageLoopResponsive(hwnd, interval) { |
| 63 | recordMainThreadHeartbeat(now) |
| 64 | } |
| 65 | } |
| 66 | } |
| 67 | }() |
| 68 | } |
| 69 | |
| 70 | func stopNativeMainThreadHeartbeat() { |
| 71 | windowsHeartbeatMu.Lock() |
| 72 | stop := windowsHeartbeatStop |
| 73 | windowsHeartbeatStop = nil |
| 74 | windowsHeartbeatMu.Unlock() |
| 75 | if stop != nil { |
| 76 | close(stop) |
| 77 | } |
| 78 | } |
| 79 | |
| 80 | func currentProcessTopLevelWindow() uintptr { |
| 81 | // Go's Windows callback table is process-lifetime state with a finite |
| 82 | // capacity. Reuse one callback instead of consuming an entry on every |
| 83 | // one-second heartbeat. |
| 84 | enumWindowsMu.Lock() |
| 85 | defer enumWindowsMu.Unlock() |
| 86 | enumWindowsPID = uint32(os.Getpid()) |
| 87 | enumWindowsFound = 0 |
| 88 | enumWindowsProc.Call(enumWindowsCallback, 0) |
| 89 | return enumWindowsFound |
| 90 | } |
| 91 | |
| 92 | func enumCurrentProcessTopLevelWindow(hwnd uintptr, _ uintptr) uintptr { |
| 93 | var windowPID uint32 |
| 94 | getWindowThreadProcessProc.Call(hwnd, uintptr(unsafe.Pointer(&windowPID))) |
| 95 | if windowPID == enumWindowsPID && windowClassName(hwnd) == "wailsWindow" { |
| 96 | enumWindowsFound = hwnd |
| 97 | return 0 |
| 98 | } |
| 99 | return 1 |
| 100 | } |
| 101 | |
| 102 | func windowClassName(hwnd uintptr) string { |
| 103 | var name [256]uint16 |
| 104 | n, _, _ := getClassNameProc.Call( |
| 105 | hwnd, |
| 106 | uintptr(unsafe.Pointer(&name[0])), |
| 107 | uintptr(len(name)), |
| 108 | ) |
| 109 | if n == 0 { |
| 110 | return "" |
| 111 | } |
| 112 | return windows.UTF16ToString(name[:n]) |
| 113 | } |
| 114 | |
| 115 | func windowMessageLoopResponsive(hwnd uintptr, timeout time.Duration) bool { |
| 116 | timeoutMS := timeout.Milliseconds() |
| 117 | if timeoutMS < 250 { |
| 118 | timeoutMS = 250 |
| 119 | } |
| 120 | var result uintptr |
| 121 | ok, _, _ := sendMessageTimeoutProc.Call( |
| 122 | hwnd, |
| 123 | wmNull, |
| 124 | 0, |
| 125 | 0, |
| 126 | smtoBlock|smtoAbortIfHung, |
| 127 | uintptr(timeoutMS), |
| 128 | uintptr(unsafe.Pointer(&result)), |
| 129 | ) |
| 130 | return ok != 0 |
| 131 | } |
| 132 |