GetHandleWithTimeout is in charge of resolving handle names on handle instances that are under the risk of producing a deadlock, and thus hanging the caller thread. To prevent this kind of unwanted scenarios, deadlock aware timeout calls into `NtQueryObject` in a separate native thread. The thread i
(handle windows.Handle, timeout uint32)
| 58 | // If the query thread doesn't notify the main thread after a prudent timeout, then the query thread is killed. |
| 59 | // Subsequent calls for handle name resolution will recreate the thread in case of it not being alive. |
| 60 | func GetHandleWithTimeout(handle windows.Handle, timeout uint32) (string, error) { |
| 61 | if tmt.thread == 0 { |
| 62 | if err := windows.ResetEvent(tmt.ini); err != nil { |
| 63 | return "", fmt.Errorf("couldn't reset init event: %v", err) |
| 64 | } |
| 65 | if err := windows.ResetEvent(tmt.done); err != nil { |
| 66 | return "", fmt.Errorf("couldn't reset done event: %v", err) |
| 67 | } |
| 68 | tmt.in = make(chan windows.Handle, 1) |
| 69 | tmt.out = make(chan string, 1) |
| 70 | tmt.thread = sys.CreateThread( |
| 71 | nil, |
| 72 | 0, |
| 73 | windows.NewCallback(timeoutFn), |
| 74 | 0, |
| 75 | 0, |
| 76 | nil) |
| 77 | if tmt.thread == 0 { |
| 78 | return "", fmt.Errorf("cannot create handle query thread: %v", windows.GetLastError()) |
| 79 | } |
| 80 | } |
| 81 | |
| 82 | tmt.in <- handle |
| 83 | if err := windows.SetEvent(tmt.ini); err != nil { |
| 84 | return "", err |
| 85 | } |
| 86 | |
| 87 | evt, err := windows.WaitForSingleObject(tmt.done, timeout) |
| 88 | if err != nil || evt == windows.WAIT_FAILED { |
| 89 | // consume pushed handle |
| 90 | <-tmt.in |
| 91 | return "", nil |
| 92 | } |
| 93 | if evt == windows.WAIT_OBJECT_0 { |
| 94 | return <-tmt.out, nil |
| 95 | } |
| 96 | if windows.Errno(evt) == windows.WAIT_TIMEOUT { |
| 97 | waitTimeoutCounts.Add(1) |
| 98 | // kill the thread and wait for its termination to orderly cleanup resources |
| 99 | if err := sys.TerminateThread(tmt.thread, 0); err != nil { |
| 100 | return "", fmt.Errorf("unable tmt terminate timeout thread: %v", err) |
| 101 | } |
| 102 | if _, err := windows.WaitForSingleObject(tmt.thread, timeout); err != nil { |
| 103 | tmt.thread = 0 |
| 104 | return "", fmt.Errorf("failed awaiting timeout thread termination: %v", err) |
| 105 | } |
| 106 | _ = windows.CloseHandle(tmt.thread) |
| 107 | tmt.thread = 0 |
| 108 | return "", errors.New("couldn't resolve handle name due to timeout") |
| 109 | } |
| 110 | return "", nil |
| 111 | } |
| 112 | |
| 113 | // CloseTimeout releases event and thread handles. |
| 114 | func CloseTimeout() error { |