[cfe-commits] r149204 - /cfe/trunk/lib/Frontend/CompilerInstance.cpp
Douglas Gregor
dgregor at apple.com
Sun Jan 29 12:15:24 PST 2012
Author: dgregor
Date: Sun Jan 29 14:15:24 2012
New Revision: 149204
URL: http://llvm.org/viewvc/llvm-project?rev=149204&view=rev
Log:
Switch over to LLVM's file-level locking facility
Modified:
cfe/trunk/lib/Frontend/CompilerInstance.cpp
Modified: cfe/trunk/lib/Frontend/CompilerInstance.cpp
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/Frontend/CompilerInstance.cpp?rev=149204&r1=149203&r2=149204&view=diff
==============================================================================
--- cfe/trunk/lib/Frontend/CompilerInstance.cpp (original)
+++ cfe/trunk/lib/Frontend/CompilerInstance.cpp Sun Jan 29 14:15:24 2012
@@ -37,6 +37,7 @@
#include "llvm/ADT/Statistic.h"
#include "llvm/Support/Timer.h"
#include "llvm/Support/Host.h"
+#include "llvm/Support/LockFileManager.h"
#include "llvm/Support/Path.h"
#include "llvm/Support/Program.h"
#include "llvm/Support/Signals.h"
@@ -44,18 +45,6 @@
#include "llvm/Support/CrashRecoveryContext.h"
#include "llvm/Config/config.h"
-// Support for FileLockManager
-#include <fstream>
-#include <sys/types.h>
-#include <sys/stat.h>
-
-#if LLVM_ON_WIN32
-#include <windows.h>
-#endif
-#if LLVM_ON_UNIX
-#include <unistd.h>
-#endif
-
using namespace clang;
CompilerInstance::CompilerInstance()
@@ -715,270 +704,21 @@
Data.Instance.ExecuteAction(Data.CreateModuleAction);
}
-namespace {
- /// \brief Class that manages the creation of a lock file to aid
- /// implicit coordination between different processes.
- ///
- /// The implicit coordination works by creating a ".lock" file alongside
- /// the file that we're coordinating for, using the atomicity of the file
- /// system to ensure that only a single process can create that ".lock" file.
- /// When the lock file is removed, the owning process has finished the
- /// operation.
- class LockFileManager {
- public:
- /// \brief Describes the state of a lock file.
- enum LockFileState {
- /// \brief The lock file has been created and is owned by this instance
- /// of the object.
- LFS_Owned,
- /// \brief The lock file already exists and is owned by some other
- /// instance.
- LFS_Shared,
- /// \brief An error occurred while trying to create or find the lock
- /// file.
- LFS_Error
- };
-
- private:
- llvm::SmallString<128> LockFileName;
- llvm::SmallString<128> UniqueLockFileName;
-
- llvm::Optional<std::pair<std::string, int> > Owner;
- llvm::Optional<llvm::error_code> Error;
-
- LockFileManager(const LockFileManager &);
- LockFileManager &operator=(const LockFileManager &);
-
- static llvm::Optional<std::pair<std::string, int> >
- readLockFile(StringRef LockFileName);
-
- static bool processStillExecuting(StringRef Hostname, int PID);
-
- public:
-
- LockFileManager(StringRef FileName);
- ~LockFileManager();
-
- /// \brief Determine the state of the lock file.
- LockFileState getState() const;
-
- operator LockFileState() const { return getState(); }
-
- /// \brief For a shared lock, wait until the owner releases the lock.
- void waitForUnlock();
- };
-}
-
-/// \brief Attempt to read the lock file with the given name, if it exists.
-///
-/// \param LockFileName The name of the lock file to read.
-///
-/// \returns The process ID of the process that owns this lock file
-llvm::Optional<std::pair<std::string, int> >
-LockFileManager::readLockFile(StringRef LockFileName) {
- // Check whether the lock file exists. If not, clearly there's nothing
- // to read, so we just return.
- bool Exists = false;
- if (llvm::sys::fs::exists(LockFileName, Exists) || !Exists)
- return llvm::Optional<std::pair<std::string, int> >();
-
- // Read the owning host and PID out of the lock file. If it appears that the
- // owning process is dead, the lock file is invalid.
- int PID = 0;
- std::string Hostname;
- std::ifstream Input(LockFileName.str().c_str());
- if (Input >> Hostname >> PID && PID > 0 &&
- processStillExecuting(Hostname, PID))
- return std::make_pair(Hostname, PID);
-
- // Delete the lock file. It's invalid anyway.
- bool Existed;
- llvm::sys::fs::remove(LockFileName, Existed);
- return llvm::Optional<std::pair<std::string, int> >();
-}
-
-bool LockFileManager::processStillExecuting(StringRef Hostname, int PID) {
-#if LLVM_ON_UNIX
- char MyHostname[256];
- MyHostname[255] = 0;
- MyHostname[0] = 0;
- gethostname(MyHostname, 255);
- // Check whether the process is dead. If so, we're done.
- if (MyHostname == Hostname && getsid(PID) == -1 && errno == ESRCH)
- return false;
-#endif
-
- return true;
-}
-
-LockFileManager::LockFileManager(StringRef FileName)
-{
- LockFileName = FileName;
- LockFileName += ".lock";
-
- // If the lock file already exists, don't bother to try to create our own
- // lock file; it won't work anyway. Just figure out who owns this lock file.
- if ((Owner = readLockFile(LockFileName)))
- return;
-
- // Create a lock file that is unique to this instance.
- UniqueLockFileName = LockFileName;
- UniqueLockFileName += "-%%%%%%%%";
- int UniqueLockFileID;
- if (llvm::error_code EC
- = llvm::sys::fs::unique_file(UniqueLockFileName.str(),
- UniqueLockFileID,
- UniqueLockFileName,
- /*makeAbsolute=*/false)) {
- Error = EC;
- return;
- }
-
- // Write our process ID to our unique lock file.
- {
- llvm::raw_fd_ostream Out(UniqueLockFileID, /*shouldClose=*/true);
-
-#if LLVM_ON_UNIX
- // FIXME: move getpid() call into LLVM
- 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()) {
- // We failed to write out PID, so make up an excuse, remove the
- // unique lock file, and fail.
- Error = llvm::make_error_code(llvm::errc::no_space_on_device);
- bool Existed;
- llvm::sys::fs::remove(UniqueLockFileName.c_str(), Existed);
- return;
- }
- }
-
- // Create a hard link from the lock file name. If this succeeds, we're done.
- llvm::error_code EC
- = llvm::sys::fs::create_hard_link(UniqueLockFileName.str(),
- LockFileName.str());
- if (EC == llvm::errc::success)
- return;
-
- // Creating the hard link failed.
-
-#ifdef LLVM_ON_UNIX
- // The creation of the hard link may appear to fail, but if stat'ing the
- // unique file returns a link count of 2, then we can still declare success.
- struct stat StatBuf;
- if (stat(UniqueLockFileName.c_str(), &StatBuf) == 0 &&
- StatBuf.st_nlink == 2)
- return;
-#endif
-
- // Someone else managed to create the lock file first. Wipe out our unique
- // lock file (it's useless now) and read the process ID from the lock file.
- bool Existed;
- llvm::sys::fs::remove(UniqueLockFileName.str(), Existed);
- if ((Owner = readLockFile(LockFileName)))
- return;
-
- // There is a lock file that nobody owns; try to clean it up and report
- // an error.
- llvm::sys::fs::remove(LockFileName.str(), Existed);
- Error = EC;
-}
-
-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;
-
- // Since we own the lock, remove the lock file and our own unique lock file.
- bool Existed;
- llvm::sys::fs::remove(LockFileName.str(), Existed);
- llvm::sys::fs::remove(UniqueLockFileName.str(), Existed);
-}
-
-void LockFileManager::waitForUnlock() {
- if (getState() != LFS_Shared)
- return;
-
-#if LLVM_ON_WIN32
- unsigned long Interval = 1;
-#else
- struct timespec Interval;
- 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;
- do {
- // Sleep for the designated interval, to allow the owning process time to
- // finish up and remove the lock file.
- // FIXME: Should we hook in to system APIs to get a notification when the
- // lock file is deleted?
-#if LLVM_ON_WIN32
- Sleep(Interval);
-#else
- nanosleep(&Interval, NULL);
-#endif
- // If the file no longer exists, we're done.
- bool Exists = false;
- if (!llvm::sys::fs::exists(LockFileName.str(), Exists) && !Exists)
- return;
-
- if (!processStillExecuting((*Owner).first, (*Owner).second))
- return;
-
- // Exponentially increase the time we wait for the lock to be removed.
-#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
- );
-
- // Give up.
-}
-
/// \brief Compile a module file for the given module, using the options
/// provided by the importing compiler instance.
static void compileModule(CompilerInstance &ImportingInstance,
Module *Module,
StringRef ModuleFileName) {
- LockFileManager Locked(ModuleFileName);
+ llvm::LockFileManager Locked(ModuleFileName);
switch (Locked) {
- case LockFileManager::LFS_Error:
+ case llvm::LockFileManager::LFS_Error:
return;
- case LockFileManager::LFS_Owned:
+ case llvm::LockFileManager::LFS_Owned:
// We're responsible for building the module ourselves. Do so below.
break;
- case LockFileManager::LFS_Shared:
+ case llvm::LockFileManager::LFS_Shared:
// Someone else is responsible for building the module. Wait for them to
// finish.
Locked.waitForUnlock();
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