| 39 | } |
| 40 | |
| 41 | bool FileLock::platformLock(LockType lockType, bool wait, bool unLockFirstIfNeeded, bool *tryAgain) { |
| 42 | auto realLockType = LockType2Flag(lockType); |
| 43 | auto flag = wait ? realLockType : (realLockType | LOCKFILE_FAIL_IMMEDIATELY); |
| 44 | if (unLockFirstIfNeeded) { |
| 45 | /* try exclusive-lock above shared-lock will always fail in Win32 |
| 46 | auto ret = LockFileEx(m_fd, realLockType | LOCKFILE_FAIL_IMMEDIATELY, 0, 1, 0, &m_overLapped); |
| 47 | if (ret) { |
| 48 | return true; |
| 49 | }*/ |
| 50 | // let's be gentleman: unlock my shared-lock to prevent deadlock |
| 51 | auto ret = UnlockFileEx(m_fd, 0, 1, 0, &m_overLapped); |
| 52 | if (!ret) { |
| 53 | auto lastError = GetLastError(); |
| 54 | if (lastError != ERROR_NOT_LOCKED) { |
| 55 | MMKVError("fail to try unlock first fd=%p, error:%d", m_fd, lastError); |
| 56 | } |
| 57 | } |
| 58 | } |
| 59 | |
| 60 | auto ret = LockFileEx(m_fd, flag, 0, 1, 0, &m_overLapped); |
| 61 | if (!ret) { |
| 62 | if (tryAgain) { |
| 63 | *tryAgain = (GetLastError() == ERROR_LOCK_VIOLATION); |
| 64 | } |
| 65 | if (wait) { |
| 66 | MMKVError("fail to lock fd=%p, error:%d", m_fd, GetLastError()); |
| 67 | } |
| 68 | // try recover my shared-lock |
| 69 | if (unLockFirstIfNeeded) { |
| 70 | ret = LockFileEx(m_fd, LockType2Flag(SharedLockType), 0, 1, 0, &m_overLapped); |
| 71 | if (!ret) { |
| 72 | // let's hope this never happen |
| 73 | MMKVError("fail to recover shared-lock fd=%p, error:%d", m_fd, GetLastError()); |
| 74 | } |
| 75 | } |
| 76 | return false; |
| 77 | } else { |
| 78 | return true; |
| 79 | } |
| 80 | } |
| 81 | |
| 82 | bool FileLock::platformUnLock(bool unlockToSharedLock) { |
| 83 | /* quote from MSDN: |
nothing calls this directly
no test coverage detected