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//== BackgroundIndexStorage.cpp - Provide caching support to BackgroundIndex ==/
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
#include "GlobalCompilationDatabase.h"
#include "Logger.h"
#include "Path.h"
#include "index/Background.h"
#include "llvm/ADT/Optional.h"
#include "llvm/ADT/STLExtras.h"
#include "llvm/ADT/ScopeExit.h"
#include "llvm/ADT/SmallString.h"
#include "llvm/ADT/SmallVector.h"
#include "llvm/ADT/StringRef.h"
#include "llvm/Support/Error.h"
#include "llvm/Support/FileSystem.h"
#include "llvm/Support/MemoryBuffer.h"
#include "llvm/Support/Path.h"
#include <functional>
namespace clang {
namespace clangd {
namespace {
std::string getShardPathFromFilePath(llvm::StringRef ShardRoot,
llvm::StringRef FilePath) {
llvm::SmallString<128> ShardRootSS(ShardRoot);
llvm::sys::path::append(ShardRootSS, llvm::sys::path::filename(FilePath) +
"." + llvm::toHex(digest(FilePath)) +
".idx");
return ShardRootSS.str();
}
llvm::Error
writeAtomically(llvm::StringRef OutPath,
llvm::function_ref<void(llvm::raw_ostream &)> Writer) {
// Write to a temporary file first.
llvm::SmallString<128> TempPath;
int FD;
auto EC =
llvm::sys::fs::createUniqueFile(OutPath + ".tmp.%%%%%%%%", FD, TempPath);
if (EC)
return llvm::errorCodeToError(EC);
// Make sure temp file is destroyed on failure.
auto RemoveOnFail =
llvm::make_scope_exit([TempPath] { llvm::sys::fs::remove(TempPath); });
llvm::raw_fd_ostream OS(FD, /*shouldClose=*/true);
Writer(OS);
OS.close();
if (OS.has_error())
return llvm::errorCodeToError(OS.error());
// Then move to real location.
EC = llvm::sys::fs::rename(TempPath, OutPath);
if (EC)
return llvm::errorCodeToError(EC);
// If everything went well, we already moved the file to another name. So
// don't delete the file, as the name might be taken by another file.
RemoveOnFail.release();
return llvm::ErrorSuccess();
}
// Uses disk as a storage for index shards. Creates a directory called
// ".clangd/index/" under the path provided during construction.
class DiskBackedIndexStorage : public BackgroundIndexStorage {
std::string DiskShardRoot;
public:
// Sets DiskShardRoot to (Directory + ".clangd/index/") which is the base
// directory for all shard files.
DiskBackedIndexStorage(llvm::StringRef Directory) {
llvm::SmallString<128> CDBDirectory(Directory);
llvm::sys::path::append(CDBDirectory, ".clangd", "index");
DiskShardRoot = CDBDirectory.str();
std::error_code OK;
std::error_code EC = llvm::sys::fs::create_directories(DiskShardRoot);
if (EC != OK) {
elog("Failed to create directory {0} for index storage: {1}",
DiskShardRoot, EC.message());
}
}
std::unique_ptr<IndexFileIn>
loadShard(llvm::StringRef ShardIdentifier) const override {
const std::string ShardPath =
getShardPathFromFilePath(DiskShardRoot, ShardIdentifier);
auto Buffer = llvm::MemoryBuffer::getFile(ShardPath);
if (!Buffer)
return nullptr;
if (auto I = readIndexFile(Buffer->get()->getBuffer()))
return llvm::make_unique<IndexFileIn>(std::move(*I));
else
elog("Error while reading shard {0}: {1}", ShardIdentifier,
I.takeError());
return nullptr;
}
llvm::Error storeShard(llvm::StringRef ShardIdentifier,
IndexFileOut Shard) const override {
return writeAtomically(
getShardPathFromFilePath(DiskShardRoot, ShardIdentifier),
[&Shard](llvm::raw_ostream &OS) { OS << Shard; });
}
};
// Doesn't persist index shards anywhere (used when the CDB dir is unknown).
// We could consider indexing into ~/.clangd/ or so instead.
class NullStorage : public BackgroundIndexStorage {
public:
std::unique_ptr<IndexFileIn>
loadShard(llvm::StringRef ShardIdentifier) const override {
return nullptr;
}
llvm::Error storeShard(llvm::StringRef ShardIdentifier,
IndexFileOut Shard) const override {
vlog("Couldn't find project for {0}, indexing in-memory only",
ShardIdentifier);
return llvm::Error::success();
}
};
// Creates and owns IndexStorages for multiple CDBs.
class DiskBackedIndexStorageManager {
public:
DiskBackedIndexStorageManager(
std::function<llvm::Optional<ProjectInfo>(PathRef)> GetProjectInfo)
: IndexStorageMapMu(llvm::make_unique<std::mutex>()),
GetProjectInfo(std::move(GetProjectInfo)) {
llvm::SmallString<128> HomeDir;
llvm::sys::path::home_directory(HomeDir);
this->HomeDir = HomeDir.str().str();
}
// Creates or fetches to storage from cache for the specified project.
BackgroundIndexStorage *operator()(PathRef File) {
std::lock_guard<std::mutex> Lock(*IndexStorageMapMu);
Path CDBDirectory = HomeDir;
if (auto PI = GetProjectInfo(File))
CDBDirectory = PI->SourceRoot;
auto &IndexStorage = IndexStorageMap[CDBDirectory];
if (!IndexStorage)
IndexStorage = create(CDBDirectory);
return IndexStorage.get();
}
private:
std::unique_ptr<BackgroundIndexStorage> create(PathRef CDBDirectory) {
if (CDBDirectory.empty()) {
elog("Tried to create storage for empty directory!");
return llvm::make_unique<NullStorage>();
}
return llvm::make_unique<DiskBackedIndexStorage>(CDBDirectory);
}
Path HomeDir;
llvm::StringMap<std::unique_ptr<BackgroundIndexStorage>> IndexStorageMap;
std::unique_ptr<std::mutex> IndexStorageMapMu;
std::function<llvm::Optional<ProjectInfo>(PathRef)> GetProjectInfo;
};
} // namespace
BackgroundIndexStorage::Factory
BackgroundIndexStorage::createDiskBackedStorageFactory(
std::function<llvm::Optional<ProjectInfo>(PathRef)> GetProjectInfo) {
return DiskBackedIndexStorageManager(std::move(GetProjectInfo));
}
} // namespace clangd
} // namespace clang
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