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tidy Win32 inter-process lock

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This commit is contained in:
guoling
2019-12-18 16:57:30 +08:00
parent d383aa71ec
commit 88f72682bf
6 changed files with 123 additions and 81 deletions
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Core/InterProcessLock.cpp
+27 -80
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@@ -26,30 +26,14 @@
#endif
namespace mmkv {
#ifndef MMKV_WIN32
static uint32_t LockType2FlockType(LockType lockType) {
switch (lockType) {
case SharedLockType:
return LOCK_SH;
case ExclusiveLockType:
return LOCK_EX;
}
return LOCK_EX;
bool FileLock::lock(LockType lockType) {
return doLock(lockType, true);
}
#else
static DWORD LockType2Flag(LockType lockType) {
DWORD flag = 0;
switch (lockType) {
case SharedLockType:
flag = 0;
break;
case ExclusiveLockType:
flag = LOCKFILE_EXCLUSIVE_LOCK;
break;
}
return flag;
bool FileLock::try_lock(LockType lockType) {
return doLock(lockType, false);
}
#endif
bool FileLock::doLock(LockType lockType, bool wait) {
if (!isFileLockValid()) {
@@ -74,8 +58,21 @@ bool FileLock::doLock(LockType lockType, bool wait) {
unLockFirstIfNeeded = true;
}
}
return platformLock(lockType, wait, unLockFirstIfNeeded);
}
#ifndef MMKV_WIN32
static uint32_t LockType2FlockType(LockType lockType) {
switch (lockType) {
case SharedLockType:
return LOCK_SH;
case ExclusiveLockType:
return LOCK_EX;
}
return LOCK_EX;
}
bool FileLock::platformLock(LockType lockType, bool wait, bool unLockFirstIfNeeded) {
auto realLockType = LockType2FlockType(lockType);
int cmd = wait ? realLockType : (realLockType | LOCK_NB);
if (unLockFirstIfNeeded) {
@@ -99,39 +96,19 @@ bool FileLock::doLock(LockType lockType, bool wait) {
} else {
return true;
}
#else
auto realLockType = LockType2Flag(lockType);
auto flag = wait ? realLockType : (realLockType | LOCKFILE_FAIL_IMMEDIATELY);
if (unLockFirstIfNeeded) {
/* try exclusive-lock above shared-lock will always fail in Win32
auto ret = LockFileEx(m_fd, realLockType | LOCKFILE_FAIL_IMMEDIATELY, 0, 1, 0, &m_overLapped);
if (ret) {
return true;
}*/
// lets be gentleman: unlock my shared-lock to prevent deadlock
auto ret = UnlockFileEx(m_fd, 0, 1, 0, &m_overLapped);
if (!ret) {
MMKVError("fail to try unlock first fd=%p, error:%d", m_fd, GetLastError());
}
}
}
auto ret = LockFileEx(m_fd, flag, 0, 1, 0, &m_overLapped);
if (!ret) {
MMKVError("fail to lock fd=%p, error:%d", m_fd, GetLastError());
bool FileLock::platformUnLock(LockType lockType, bool unlockToSharedLock) {
int cmd = unlockToSharedLock ? LOCK_SH : LOCK_UN;
auto ret = flock(m_fd, cmd);
if (ret != 0) {
MMKVError("fail to unlock fd=%d, ret=%d, error:%s", m_fd, ret, strerror(errno));
return false;
} else {
return true;
}
}
#endif
}
bool FileLock::lock(LockType lockType) {
return doLock(lockType, true);
}
bool FileLock::try_lock(LockType lockType) {
return doLock(lockType, false);
}
bool FileLock::unlock(LockType lockType) {
if (!isFileLockValid()) {
@@ -161,37 +138,7 @@ bool FileLock::unlock(LockType lockType) {
unlockToSharedLock = true;
}
}
#ifndef MMKV_WIN32
int cmd = unlockToSharedLock ? LOCK_SH : LOCK_UN;
auto ret = flock(m_fd, cmd);
if (ret != 0) {
MMKVError("fail to unlock fd=%d, ret=%d, error:%s", m_fd, ret, strerror(errno));
return false;
} else {
return true;
}
#else
/* quote from MSDN:
* If the same range is locked with an exclusive and a shared lock,
* two unlock operations are necessary to unlock the region;
* the first unlock operation unlocks the exclusive lock,
* the second unlock operation unlocks the shared lock.
*/
if (unlockToSharedLock) {
auto flag = LockType2Flag(SharedLockType);
if (!LockFileEx(m_fd, flag, 0, 1, 0, &m_overLapped)) {
MMKVError("fail to roll back to shared-lock, error:%d", GetLastError());
}
}
auto ret = UnlockFileEx(m_fd, 0, 1, 0, &m_overLapped);
if (!ret) {
MMKVError("fail to unlock fd=%p, error:%d", m_fd, GetLastError());
return false;
} else {
return true;
}
#endif
return platformUnLock(lockType, unlockToSharedLock);
}
} // namespace mmkv