6502/llvm-6502
1
0
Fork 0
mirror of https://github.com/c64scene-ar/llvm-6502.git synced 2025-06-17 04:24:00 +00:00
Code Issues Projects Releases Wiki Activity

[Support/LockFileManager] Make the LockFileManager more robust against races.

Browse Source 
There was a race where:
- The LockFileManager tries to own the lock file and fails.
- The other owner then releases and removes the lock file.
- The LockFileManager tries to read the owner info from the lock file but fails now.

In such a case have LockFileManager try to get ownership again, instead of error'ing out.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@203138 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Argyrios Kyrtzidis
2014-03-06 17:37:10 +00:00
parent 7b95c0d529
commit d25733bebc
1 changed files with 34 additions and 17 deletions
Download Patch File Download Diff File Expand all files Collapse all files

51
lib/Support/LockFileManager.cpp
View File

@ -115,25 +115,42 @@ LockFileManager::LockFileManager(StringRef FileName)
} }
} }
// Create a symbolic link from the lock file name. If this succeeds, we're done. while (1) {
// Note that we are using symbolic link because hard links are not supported // Create a symbolic link from the lock file name. If this succeeds, we're
// by all filesystems. // done. Note that we are using symbolic link because hard links are not
error_code EC // supported by all filesystems.
= sys::fs::create_symbolic_link(UniqueLockFileName.str(), error_code EC
LockFileName.str()); = sys::fs::create_symbolic_link(UniqueLockFileName.str(),
if (EC == errc::success) LockFileName.str());
return; if (EC == errc::success)
return;
// Someone else managed to create the lock file first. Wipe out our unique if (EC != errc::file_exists) {
// lock file (it's useless now) and read the process ID from the lock file. Error = EC;
sys::fs::remove(UniqueLockFileName.str()); return;
if ((Owner = readLockFile(LockFileName))) }
return;
// There is a lock file that nobody owns; try to clean it up and report // Someone else managed to create the lock file first. Read the process ID
// an error. // from the lock file.
sys::fs::remove(LockFileName.str()); if ((Owner = readLockFile(LockFileName))) {
Error = EC; // Wipe out our unique lock file (it's useless now)
sys::fs::remove(UniqueLockFileName.str());
return;
}
if (!sys::fs::exists(LockFileName.str())) {
// The previous owner released the lock file before we could read it.
// Try to get ownership again.
continue;
}
// There is a lock file that nobody owns; try to clean it up and get
// ownership.
if ((EC = sys::fs::remove(LockFileName.str()))) {
Error = EC;
return;
}
}
} }
LockFileManager::LockFileState LockFileManager::getState() const { LockFileManager::LockFileState LockFileManager::getState() const {