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<rdar://problem/13551789> Fix a race in the LockFileManager. 

It's possible for the lock file to disappear and the owning process to
return before we're able to see the generated file. Spin for a little
while to see if it shows up before failing. 

llvm-svn: 178909
This commit is contained in:
Douglas Gregor 2013-04-05 20:53:57 +00:00
parent 6bd4d8cf72
commit 0cb6846090
1 changed files with 32 additions and 5 deletions
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37
llvm/lib/Support/LockFileManager.cpp
View File

@ -174,8 +174,8 @@ void LockFileManager::waitForUnlock() {
Interval.tv_sec = 0;
Interval.tv_nsec = 1000000;
#endif
// Don't wait more than an hour for the file to appear.
const unsigned MaxSeconds = 3600;
// Don't wait more than five minutes for the file to appear.
unsigned MaxSeconds = 300;
bool LockFileGone = false;
do {
// Sleep for the designated interval, to allow the owning process time to
@ -187,21 +187,48 @@ void LockFileManager::waitForUnlock() {
#else
nanosleep(&Interval, NULL);
#endif
// If the lock file no longer exists, wait for the actual file.
bool Exists = false;
bool LockFileJustDisappeared = false;
// If the lock file is still expected to be there, check whether it still
// is.
if (!LockFileGone) {
if (!sys::fs::exists(LockFileName.str(), Exists) && !Exists) {
LockFileGone = true;
LockFileJustDisappeared = true;
Exists = false;
}
}
// If the lock file is no longer there, check if the original file is
// available now.
if (LockFileGone) {
if (!sys::fs::exists(FileName.str(), Exists) && Exists)
if (!sys::fs::exists(FileName.str(), Exists) && Exists) {
return;
}
// The lock file is gone, so now we're waiting for the original file to
// show up. If this just happened, reset our waiting intervals and keep
// waiting.
if (LockFileJustDisappeared) {
MaxSeconds = 5;
#if LLVM_ON_WIN32
Interval = 1;
#else
Interval.tv_sec = 0;
Interval.tv_nsec = 1000000;
#endif
continue;
}
}
if (!processStillExecuting((*Owner).first, (*Owner).second))
// If we're looking for the lock file to disappear, but the process
// owning the lock died without cleaning up, just bail out.
if (!LockFileGone &&
!processStillExecuting((*Owner).first, (*Owner).second)) {
return;
}
// Exponentially increase the time we wait for the lock to be removed.
#if LLVM_ON_WIN32