https://github.com/jansvoboda11 created
https://github.com/llvm/llvm-project/pull/130627
This patch removes some internal state out of `LockFileManager` by moving the
locking code from the constructor into new member function `tryLock()` which
returns the errors right away. This simplifies and modernizes the interface.
>From 88b5bbd1303480dc40db3ea76d0f831a69ff1957 Mon Sep 17 00:00:00 2001
From: Jan Svoboda <jan_svob...@apple.com>
Date: Sat, 8 Mar 2025 21:51:51 -0800
Subject: [PATCH] [Support] Return `LockFileManager` errors right away
---
clang/lib/Frontend/CompilerInstance.cpp | 23 +++--
clang/lib/Serialization/GlobalModuleIndex.cpp | 17 ++--
llvm/include/llvm/Support/LockFileManager.h | 33 +------
llvm/lib/Support/LockFileManager.cpp | 91 ++++++-------------
llvm/lib/Target/AMDGPU/AMDGPUSplitModule.cpp | 20 ++--
5 files changed, 59 insertions(+), 125 deletions(-)
diff --git a/clang/lib/Frontend/CompilerInstance.cpp
b/clang/lib/Frontend/CompilerInstance.cpp
index c11c857ea0606..fe351e6b41342 100644
--- a/clang/lib/Frontend/CompilerInstance.cpp
+++ b/clang/lib/Frontend/CompilerInstance.cpp
@@ -1477,29 +1477,28 @@ static bool compileModuleAndReadASTBehindLock(
llvm::sys::fs::create_directories(Dir);
while (true) {
- llvm::LockFileManager Locked(ModuleFileName);
- switch (Locked) {
- case llvm::LockFileManager::LFS_Error:
+ llvm::LockFileManager Lock(ModuleFileName);
+ bool Owned;
+ if (llvm::Error Err = Lock.tryLock().moveInto(Owned)) {
// ModuleCache takes care of correctness and locks are only necessary for
// performance. Fallback to building the module in case of any lock
// related errors.
Diags.Report(ModuleNameLoc, diag::remark_module_lock_failure)
- << Module->Name << Locked.getErrorMessage();
+ << Module->Name << toString(std::move(Err));
// Clear out any potential leftover.
- Locked.unsafeRemoveLockFile();
- [[fallthrough]];
- case llvm::LockFileManager::LFS_Owned:
+ Lock.unsafeRemoveLockFile();
+ return compileModuleAndReadASTImpl(ImportingInstance, ImportLoc,
+ ModuleNameLoc, Module, ModuleFileName);
+ }
+ if (Owned) {
// We're responsible for building the module ourselves.
return compileModuleAndReadASTImpl(ImportingInstance, ImportLoc,
ModuleNameLoc, Module,
ModuleFileName);
-
- case llvm::LockFileManager::LFS_Shared:
- break; // The interesting case.
}
// Someone else is responsible for building the module. Wait for them to
// finish.
- switch (Locked.waitForUnlock()) {
+ switch (Lock.waitForUnlock()) {
case llvm::LockFileManager::Res_Success:
break; // The interesting case.
case llvm::LockFileManager::Res_OwnerDied:
@@ -1511,7 +1510,7 @@ static bool compileModuleAndReadASTBehindLock(
Diags.Report(ModuleNameLoc, diag::remark_module_lock_timeout)
<< Module->Name;
// Clear the lock file so that future invocations can make progress.
- Locked.unsafeRemoveLockFile();
+ Lock.unsafeRemoveLockFile();
continue;
}
diff --git a/clang/lib/Serialization/GlobalModuleIndex.cpp
b/clang/lib/Serialization/GlobalModuleIndex.cpp
index 4b920fccecac3..1e2272c48bd04 100644
--- a/clang/lib/Serialization/GlobalModuleIndex.cpp
+++ b/clang/lib/Serialization/GlobalModuleIndex.cpp
@@ -849,22 +849,21 @@ GlobalModuleIndex::writeIndex(FileManager &FileMgr,
// Coordinate building the global index file with other processes that might
// try to do the same.
- llvm::LockFileManager Locked(IndexPath);
- switch (Locked) {
- case llvm::LockFileManager::LFS_Error:
+ llvm::LockFileManager Lock(IndexPath);
+ bool Owned;
+ if (llvm::Error Err = Lock.tryLock().moveInto(Owned)) {
+ llvm::consumeError(std::move(Err));
return llvm::createStringError(std::errc::io_error, "LFS error");
-
- case llvm::LockFileManager::LFS_Owned:
- // We're responsible for building the index ourselves. Do so below.
- break;
-
- case llvm::LockFileManager::LFS_Shared:
+ }
+ if (!Owned) {
// Someone else is responsible for building the index. We don't care
// when they finish, so we're done.
return llvm::createStringError(std::errc::device_or_resource_busy,
"someone else is building the index");
}
+ // We're responsible for building the index ourselves.
+
// The module index builder.
GlobalModuleIndexBuilder Builder(FileMgr, PCHContainerRdr);
diff --git a/llvm/include/llvm/Support/LockFileManager.h
b/llvm/include/llvm/Support/LockFileManager.h
index 92c7ceed6a929..e687f3b1dfa53 100644
--- a/llvm/include/llvm/Support/LockFileManager.h
+++ b/llvm/include/llvm/Support/LockFileManager.h
@@ -9,6 +9,7 @@
#define LLVM_SUPPORT_LOCKFILEMANAGER_H
#include "llvm/ADT/SmallString.h"
+#include "llvm/Support/Error.h"
#include <optional>
#include <system_error>
#include <utility> // for std::pair
@@ -26,19 +27,6 @@ class StringRef;
/// operation.
class LockFileManager {
public:
- /// Describes the state of a lock file.
- enum LockFileState {
- /// The lock file has been created and is owned by this instance
- /// of the object.
- LFS_Owned,
- /// The lock file already exists and is owned by some other
- /// instance.
- LFS_Shared,
- /// An error occurred while trying to create or find the lock
- /// file.
- LFS_Error
- };
-
/// Describes the result of waiting for the owner to release the lock.
enum WaitForUnlockResult {
/// The lock was released successfully.
@@ -55,8 +43,6 @@ class LockFileManager {
SmallString<128> UniqueLockFileName;
std::optional<std::pair<std::string, int>> Owner;
- std::error_code ErrorCode;
- std::string ErrorDiagMsg;
LockFileManager(const LockFileManager &) = delete;
LockFileManager &operator=(const LockFileManager &) = delete;
@@ -71,10 +57,10 @@ class LockFileManager {
LockFileManager(StringRef FileName);
~LockFileManager();
- /// Determine the state of the lock file.
- LockFileState getState() const;
-
- operator LockFileState() const { return getState(); }
+ /// Tries to acquire the lock without blocking.
+ /// \returns true if the lock was successfully acquired, false if the lock is
+ /// already held by someone else, or \c Error in case of unexpected failure.
+ Expected<bool> tryLock();
/// For a shared lock, wait until the owner releases the lock.
/// Total timeout for the file to appear is ~1.5 minutes.
@@ -84,15 +70,6 @@ class LockFileManager {
/// Remove the lock file. This may delete a different lock file than
/// the one previously read if there is a race.
std::error_code unsafeRemoveLockFile();
-
- /// Get error message, or "" if there is no error.
- std::string getErrorMessage() const;
-
- /// Set error and error message
- void setError(const std::error_code &EC, StringRef ErrorMsg = "") {
- ErrorCode = EC;
- ErrorDiagMsg = ErrorMsg.str();
- }
};
} // end namespace llvm
diff --git a/llvm/lib/Support/LockFileManager.cpp
b/llvm/lib/Support/LockFileManager.cpp
index 9a45a9966458e..1ec206415a13c 100644
--- a/llvm/lib/Support/LockFileManager.cpp
+++ b/llvm/lib/Support/LockFileManager.cpp
@@ -157,42 +157,35 @@ class RemoveUniqueLockFileOnSignal {
} // end anonymous namespace
-LockFileManager::LockFileManager(StringRef FileName)
-{
- this->FileName = FileName;
- if (std::error_code EC = sys::fs::make_absolute(this->FileName)) {
- std::string S("failed to obtain absolute path for ");
- S.append(std::string(this->FileName));
- setError(EC, S);
- return;
- }
- LockFileName = this->FileName;
+LockFileManager::LockFileManager(StringRef FileName) : FileName(FileName) {}
+
+Expected<bool> LockFileManager::tryLock() {
+ SmallString<128> AbsoluteFileName(FileName);
+ if (std::error_code EC = sys::fs::make_absolute(AbsoluteFileName))
+ return createStringError("failed to obtain absolute path for " +
+ AbsoluteFileName);
+ LockFileName = AbsoluteFileName;
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;
+ return false;
// Create a lock file that is unique to this instance.
UniqueLockFileName = LockFileName;
UniqueLockFileName += "-%%%%%%%%";
int UniqueLockFileID;
if (std::error_code EC = sys::fs::createUniqueFile(
- UniqueLockFileName, UniqueLockFileID, UniqueLockFileName)) {
- std::string S("failed to create unique file ");
- S.append(std::string(UniqueLockFileName));
- setError(EC, S);
- return;
- }
+ UniqueLockFileName, UniqueLockFileID, UniqueLockFileName))
+ return createStringError("failed to create unique file " +
+ UniqueLockFileName);
// Write our process ID to our unique lock file.
{
SmallString<256> HostID;
- if (auto EC = getHostID(HostID)) {
- setError(EC, "failed to get host id");
- return;
- }
+ if (auto EC = getHostID(HostID))
+ return createStringError(EC, "failed to get host id");
raw_fd_ostream Out(UniqueLockFileID, /*shouldClose=*/true);
Out << HostID << ' ' << sys::Process::getProcessId();
@@ -201,13 +194,12 @@ LockFileManager::LockFileManager(StringRef FileName)
if (Out.has_error()) {
// We failed to write out PID, so report the error, remove the
// unique lock file, and fail.
- std::string S("failed to write to ");
- S.append(std::string(UniqueLockFileName));
- setError(Out.error(), S);
+ Error Err = createStringError(Out.error(),
+ "failed to write to " +
UniqueLockFileName);
sys::fs::remove(UniqueLockFileName);
// Don't call report_fatal_error.
Out.clear_error();
- return;
+ return std::move(Err);
}
}
@@ -221,23 +213,19 @@ LockFileManager::LockFileManager(StringRef FileName)
sys::fs::create_link(UniqueLockFileName, LockFileName);
if (!EC) {
RemoveUniqueFile.lockAcquired();
- return;
+ return true;
}
- if (EC != errc::file_exists) {
- std::string S("failed to create link ");
- raw_string_ostream OSS(S);
- OSS << LockFileName.str() << " to " << UniqueLockFileName.str();
- setError(EC, S);
- return;
- }
+ if (EC != errc::file_exists)
+ return createStringError(EC, "failed to create link " + LockFileName +
+ " to " + UniqueLockFileName);
// Someone else managed to create the lock file first. Read the process ID
// from the lock file.
if ((Owner = readLockFile(LockFileName))) {
// Wipe out our unique lock file (it's useless now)
sys::fs::remove(UniqueLockFileName);
- return;
+ return false;
}
if (!sys::fs::exists(LockFileName)) {
@@ -248,39 +236,14 @@ LockFileManager::LockFileManager(StringRef FileName)
// There is a lock file that nobody owns; try to clean it up and get
// ownership.
- if ((EC = sys::fs::remove(LockFileName))) {
- std::string S("failed to remove lockfile ");
- S.append(std::string(UniqueLockFileName));
- setError(EC, S);
- return;
- }
- }
-}
-
-LockFileManager::LockFileState LockFileManager::getState() const {
- if (Owner)
- return LFS_Shared;
-
- if (ErrorCode)
- return LFS_Error;
-
- return LFS_Owned;
-}
-
-std::string LockFileManager::getErrorMessage() const {
- if (ErrorCode) {
- std::string Str(ErrorDiagMsg);
- std::string ErrCodeMsg = ErrorCode.message();
- raw_string_ostream OSS(Str);
- if (!ErrCodeMsg.empty())
- OSS << ": " << ErrCodeMsg;
- return Str;
+ if ((EC = sys::fs::remove(LockFileName)))
+ return createStringError(EC, "failed to remove lockfile " +
+ UniqueLockFileName);
}
- return "";
}
LockFileManager::~LockFileManager() {
- if (getState() != LFS_Owned)
+ if (Owner)
return;
// Since we own the lock, remove the lock file and our own unique lock file.
@@ -293,7 +256,7 @@ LockFileManager::~LockFileManager() {
LockFileManager::WaitForUnlockResult
LockFileManager::waitForUnlock(const unsigned MaxSeconds) {
- if (getState() != LFS_Shared)
+ if (!Owner)
return Res_Success;
// Since we don't yet have an event-based method to wait for the lock file,
diff --git a/llvm/lib/Target/AMDGPU/AMDGPUSplitModule.cpp
b/llvm/lib/Target/AMDGPU/AMDGPUSplitModule.cpp
index 65aee2f70104b..65cbb13628301 100644
--- a/llvm/lib/Target/AMDGPU/AMDGPUSplitModule.cpp
+++ b/llvm/lib/Target/AMDGPU/AMDGPUSplitModule.cpp
@@ -1545,18 +1545,16 @@ PreservedAnalyses AMDGPUSplitModulePass::run(Module &M,
<< "'\n");
while (true) {
- llvm::LockFileManager Locked(LockFilePath.str());
- switch (Locked) {
- case LockFileManager::LFS_Error:
+ llvm::LockFileManager Lock(LockFilePath.str());
+ bool Owned;
+ if (Error Err = Lock.tryLock().moveInto(Owned)) {
+ consumeError(std::move(Err));
LLVM_DEBUG(
dbgs() << "[amdgpu-split-module] unable to acquire lockfile, debug
"
"output may be mangled by other processes\n");
- Locked.unsafeRemoveLockFile();
- break;
- case LockFileManager::LFS_Owned:
- break;
- case LockFileManager::LFS_Shared: {
- switch (Locked.waitForUnlock()) {
+ Lock.unsafeRemoveLockFile();
+ } else if (!Owned) {
+ switch (Lock.waitForUnlock()) {
case LockFileManager::Res_Success:
break;
case LockFileManager::Res_OwnerDied:
@@ -1566,11 +1564,9 @@ PreservedAnalyses AMDGPUSplitModulePass::run(Module &M,
dbgs()
<< "[amdgpu-split-module] unable to acquire lockfile, debug "
"output may be mangled by other processes\n");
- Locked.unsafeRemoveLockFile();
+ Lock.unsafeRemoveLockFile();
break; // give up
}
- break;
- }
}
splitAMDGPUModule(TTIGetter, M, N, ModuleCallback);
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