LockFileManager.cpp [plain text]
#include "llvm/Support/LockFileManager.h"
#include "llvm/ADT/STLExtras.h"
#include "llvm/ADT/StringExtras.h"
#include "llvm/Support/FileSystem.h"
#include "llvm/Support/MemoryBuffer.h"
#include "llvm/Support/Path.h"
#include "llvm/Support/raw_ostream.h"
#include <sys/stat.h>
#include <sys/types.h>
#if LLVM_ON_WIN32
#include <windows.h>
#endif
#if LLVM_ON_UNIX
#include <unistd.h>
#endif
using namespace llvm;
Optional<std::pair<std::string, int> >
LockFileManager::readLockFile(StringRef LockFileName) {
std::unique_ptr<MemoryBuffer> MB;
if (MemoryBuffer::getFile(LockFileName, MB)) {
sys::fs::remove(LockFileName);
return None;
}
StringRef Hostname;
StringRef PIDStr;
tie(Hostname, PIDStr) = getToken(MB->getBuffer(), " ");
PIDStr = PIDStr.substr(PIDStr.find_first_not_of(" "));
int PID;
if (!PIDStr.getAsInteger(10, PID)) {
auto Owner = std::make_pair(std::string(Hostname), PID);
if (processStillExecuting(Owner.first, Owner.second))
return Owner;
}
sys::fs::remove(LockFileName);
return None;
}
bool LockFileManager::processStillExecuting(StringRef Hostname, int PID) {
#if LLVM_ON_UNIX && !defined(__ANDROID__)
char MyHostname[256];
MyHostname[255] = 0;
MyHostname[0] = 0;
gethostname(MyHostname, 255);
if (MyHostname == Hostname && getsid(PID) == -1 && errno == ESRCH)
return false;
#endif
return true;
}
LockFileManager::LockFileManager(StringRef FileName)
{
this->FileName = FileName;
if (error_code EC = sys::fs::make_absolute(this->FileName)) {
Error = EC;
return;
}
LockFileName = this->FileName;
LockFileName += ".lock";
if ((Owner = readLockFile(LockFileName)))
return;
UniqueLockFileName = LockFileName;
UniqueLockFileName += "-%%%%%%%%";
int UniqueLockFileID;
if (error_code EC
= sys::fs::createUniqueFile(UniqueLockFileName.str(),
UniqueLockFileID,
UniqueLockFileName)) {
Error = EC;
return;
}
{
raw_fd_ostream Out(UniqueLockFileID, true);
#if LLVM_ON_UNIX
char hostname[256];
hostname[255] = 0;
hostname[0] = 0;
gethostname(hostname, 255);
Out << hostname << ' ' << getpid();
#else
Out << "localhost 1";
#endif
Out.close();
if (Out.has_error()) {
Error = make_error_code(errc::no_space_on_device);
sys::fs::remove(UniqueLockFileName.c_str());
return;
}
}
while (1) {
error_code EC =
sys::fs::create_link(UniqueLockFileName.str(), LockFileName.str());
if (EC == errc::success)
return;
if (EC != errc::file_exists) {
Error = EC;
return;
}
if ((Owner = readLockFile(LockFileName))) {
sys::fs::remove(UniqueLockFileName.str());
return;
}
if (!sys::fs::exists(LockFileName.str())) {
continue;
}
if ((EC = sys::fs::remove(LockFileName.str()))) {
Error = EC;
return;
}
}
}
LockFileManager::LockFileState LockFileManager::getState() const {
if (Owner)
return LFS_Shared;
if (Error)
return LFS_Error;
return LFS_Owned;
}
LockFileManager::~LockFileManager() {
if (getState() != LFS_Owned)
return;
sys::fs::remove(LockFileName.str());
sys::fs::remove(UniqueLockFileName.str());
}
LockFileManager::WaitForUnlockResult LockFileManager::waitForUnlock() {
if (getState() != LFS_Shared)
return Res_Success;
#if LLVM_ON_WIN32
unsigned long Interval = 1;
#else
struct timespec Interval;
Interval.tv_sec = 0;
Interval.tv_nsec = 1000000;
#endif
unsigned MaxSeconds = 300;
bool LockFileGone = false;
do {
#if LLVM_ON_WIN32
Sleep(Interval);
#else
nanosleep(&Interval, NULL);
#endif
bool Exists = false;
bool LockFileJustDisappeared = false;
if (!LockFileGone) {
if (!sys::fs::exists(LockFileName.str(), Exists) && !Exists) {
LockFileGone = true;
LockFileJustDisappeared = true;
Exists = false;
}
}
if (LockFileGone) {
if (!sys::fs::exists(FileName.str(), Exists) && Exists) {
return Res_Success;
}
if (LockFileJustDisappeared) {
MaxSeconds = 5;
#if LLVM_ON_WIN32
Interval = 1;
#else
Interval.tv_sec = 0;
Interval.tv_nsec = 1000000;
#endif
continue;
}
}
if (!LockFileGone &&
!processStillExecuting((*Owner).first, (*Owner).second)) {
return Res_OwnerDied;
}
#if LLVM_ON_WIN32
Interval *= 2;
#else
Interval.tv_sec *= 2;
Interval.tv_nsec *= 2;
if (Interval.tv_nsec >= 1000000000) {
++Interval.tv_sec;
Interval.tv_nsec -= 1000000000;
}
#endif
} while (
#if LLVM_ON_WIN32
Interval < MaxSeconds * 1000
#else
Interval.tv_sec < (time_t)MaxSeconds
#endif
);
return Res_Timeout;
}