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Diffstat (limited to 'llvm/lib/CAS/UnifiedOnDiskCache.cpp')
| -rw-r--r-- | llvm/lib/CAS/UnifiedOnDiskCache.cpp | 613 |
1 files changed, 613 insertions, 0 deletions
diff --git a/llvm/lib/CAS/UnifiedOnDiskCache.cpp b/llvm/lib/CAS/UnifiedOnDiskCache.cpp new file mode 100644 index 0000000..ae9d818 --- /dev/null +++ b/llvm/lib/CAS/UnifiedOnDiskCache.cpp @@ -0,0 +1,613 @@ +//===----------------------------------------------------------------------===// +// +// 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 +// +//===----------------------------------------------------------------------===// +// +/// \file +/// Encapsulates \p OnDiskGraphDB and \p OnDiskKeyValueDB instances within one +/// directory while also restricting storage growth with a scheme of chaining +/// the two most recent directories (primary & upstream), where the primary +/// "faults-in" data from the upstream one. When the primary (most recent) +/// directory exceeds its intended limit a new empty directory becomes the +/// primary one. +/// +/// Within the top-level directory (the path that \p UnifiedOnDiskCache::open +/// receives) there are directories named like this: +/// +/// 'v<version>.<x>' +/// 'v<version>.<x+1>' +/// 'v<version>.<x+2>' +/// ... +/// +/// 'version' is the version integer for this \p UnifiedOnDiskCache's scheme and +/// the part after the dot is an increasing integer. The primary directory is +/// the one with the highest integer and the upstream one is the directory +/// before it. For example, if the sub-directories contained are: +/// +/// 'v1.5', 'v1.6', 'v1.7', 'v1.8' +/// +/// Then the primary one is 'v1.8', the upstream one is 'v1.7', and the rest are +/// unused directories that can be safely deleted at any time and by any +/// process. +/// +/// Contained within the top-level directory is a file named "lock" which is +/// used for processes to take shared or exclusive locks for the contents of the +/// top directory. While a \p UnifiedOnDiskCache is open it keeps a shared lock +/// for the top-level directory; when it closes, if the primary sub-directory +/// exceeded its limit, it attempts to get an exclusive lock in order to create +/// a new empty primary directory; if it can't get the exclusive lock it gives +/// up and lets the next \p UnifiedOnDiskCache instance that closes to attempt +/// again. +/// +/// The downside of this scheme is that while \p UnifiedOnDiskCache is open on a +/// directory, by any process, the storage size in that directory will keep +/// growing unrestricted. But the major benefit is that garbage-collection can +/// be triggered on a directory concurrently, at any time and by any process, +/// without affecting any active readers/writers in the same process or other +/// processes. +/// +/// The \c UnifiedOnDiskCache also provides validation and recovery on top of +/// the underlying on-disk storage. The low-level storage is designed to remain +/// coherent across regular process crashes, but may be invalid after power loss +/// or similar system failures. \c UnifiedOnDiskCache::validateIfNeeded allows +/// validating the contents once per boot and can recover by marking invalid +/// data for garbage collection. +/// +/// The data recovery described above requires exclusive access to the CAS, and +/// it is an error to attempt recovery if the CAS is open in any process/thread. +/// In order to maximize backwards compatibility with tools that do not perform +/// validation before opening the CAS, we do not attempt to get exclusive access +/// until recovery is actually performed, meaning as long as the data is valid +/// it will not conflict with concurrent use. +// +//===----------------------------------------------------------------------===// + +#include "llvm/CAS/UnifiedOnDiskCache.h" +#include "BuiltinCAS.h" +#include "OnDiskCommon.h" +#include "llvm/ADT/STLExtras.h" +#include "llvm/ADT/ScopeExit.h" +#include "llvm/ADT/SmallString.h" +#include "llvm/ADT/SmallVector.h" +#include "llvm/ADT/StringExtras.h" +#include "llvm/ADT/StringRef.h" +#include "llvm/CAS/ActionCache.h" +#include "llvm/CAS/OnDiskGraphDB.h" +#include "llvm/CAS/OnDiskKeyValueDB.h" +#include "llvm/Support/Compiler.h" +#include "llvm/Support/Errc.h" +#include "llvm/Support/Error.h" +#include "llvm/Support/FileSystem.h" +#include "llvm/Support/FileUtilities.h" +#include "llvm/Support/MemoryBuffer.h" +#include "llvm/Support/Path.h" +#include "llvm/Support/Program.h" +#include "llvm/Support/raw_ostream.h" +#include <optional> + +#if __has_include(<sys/sysctl.h>) +#include <sys/sysctl.h> +#endif + +using namespace llvm; +using namespace llvm::cas; +using namespace llvm::cas::ondisk; + +/// FIXME: When the version of \p DBDirPrefix is bumped up we need to figure out +/// how to handle the leftover sub-directories of the previous version, within +/// the \p UnifiedOnDiskCache::collectGarbage function. +static constexpr StringLiteral DBDirPrefix = "v1."; + +static constexpr StringLiteral ValidationFilename = "v1.validation"; +static constexpr StringLiteral CorruptPrefix = "corrupt."; + +ObjectID UnifiedOnDiskCache::getObjectIDFromValue(ArrayRef<char> Value) { + // little endian encoded. + assert(Value.size() == sizeof(uint64_t)); + return ObjectID::fromOpaqueData(support::endian::read64le(Value.data())); +} + +UnifiedOnDiskCache::ValueBytes +UnifiedOnDiskCache::getValueFromObjectID(ObjectID ID) { + // little endian encoded. + UnifiedOnDiskCache::ValueBytes ValBytes; + static_assert(ValBytes.size() == sizeof(ID.getOpaqueData())); + support::endian::write64le(ValBytes.data(), ID.getOpaqueData()); + return ValBytes; +} + +Expected<std::optional<ArrayRef<char>>> +UnifiedOnDiskCache::faultInFromUpstreamKV(ArrayRef<uint8_t> Key) { + assert(UpstreamGraphDB); + assert(UpstreamKVDB); + + std::optional<ArrayRef<char>> UpstreamValue; + if (Error E = UpstreamKVDB->get(Key).moveInto(UpstreamValue)) + return std::move(E); + if (!UpstreamValue) + return std::nullopt; + + // The value is the \p ObjectID in the context of the upstream + // \p OnDiskGraphDB instance. Translate it to the context of the primary + // \p OnDiskGraphDB instance. + ObjectID UpstreamID = getObjectIDFromValue(*UpstreamValue); + auto PrimaryID = + PrimaryGraphDB->getReference(UpstreamGraphDB->getDigest(UpstreamID)); + if (LLVM_UNLIKELY(!PrimaryID)) + return PrimaryID.takeError(); + return PrimaryKVDB->put(Key, getValueFromObjectID(*PrimaryID)); +} + +/// \returns all the 'v<version>.<x>' names of sub-directories, sorted with +/// ascending order of the integer after the dot. Corrupt directories, if +/// included, will come first. +static Expected<SmallVector<std::string, 4>> +getAllDBDirs(StringRef Path, bool IncludeCorrupt = false) { + struct DBDir { + uint64_t Order; + std::string Name; + }; + SmallVector<DBDir> FoundDBDirs; + + std::error_code EC; + for (sys::fs::directory_iterator DirI(Path, EC), DirE; !EC && DirI != DirE; + DirI.increment(EC)) { + if (DirI->type() != sys::fs::file_type::directory_file) + continue; + StringRef SubDir = sys::path::filename(DirI->path()); + if (IncludeCorrupt && SubDir.starts_with(CorruptPrefix)) { + FoundDBDirs.push_back({0, std::string(SubDir)}); + continue; + } + if (!SubDir.starts_with(DBDirPrefix)) + continue; + uint64_t Order; + if (SubDir.substr(DBDirPrefix.size()).getAsInteger(10, Order)) + return createStringError(inconvertibleErrorCode(), + "unexpected directory " + DirI->path()); + FoundDBDirs.push_back({Order, std::string(SubDir)}); + } + if (EC) + return createFileError(Path, EC); + + llvm::sort(FoundDBDirs, [](const DBDir &LHS, const DBDir &RHS) -> bool { + return LHS.Order <= RHS.Order; + }); + + SmallVector<std::string, 4> DBDirs; + for (DBDir &Dir : FoundDBDirs) + DBDirs.push_back(std::move(Dir.Name)); + return DBDirs; +} + +static Expected<SmallVector<std::string, 4>> getAllGarbageDirs(StringRef Path) { + auto DBDirs = getAllDBDirs(Path, /*IncludeCorrupt=*/true); + if (!DBDirs) + return DBDirs.takeError(); + + // FIXME: When the version of \p DBDirPrefix is bumped up we need to figure + // out how to handle the leftover sub-directories of the previous version. + + for (unsigned Keep = 2; Keep > 0 && !DBDirs->empty(); --Keep) { + StringRef Back(DBDirs->back()); + if (Back.starts_with(CorruptPrefix)) + break; + DBDirs->pop_back(); + } + return *DBDirs; +} + +/// \returns Given a sub-directory named 'v<version>.<x>', it outputs the +/// 'v<version>.<x+1>' name. +static void getNextDBDirName(StringRef DBDir, llvm::raw_ostream &OS) { + assert(DBDir.starts_with(DBDirPrefix)); + uint64_t Count; + bool Failed = DBDir.substr(DBDirPrefix.size()).getAsInteger(10, Count); + assert(!Failed); + (void)Failed; + OS << DBDirPrefix << Count + 1; +} + +static Error validateOutOfProcess(StringRef LLVMCasBinary, StringRef RootPath, + bool CheckHash) { + SmallVector<StringRef> Args{LLVMCasBinary, "-cas", RootPath, "-validate"}; + if (CheckHash) + Args.push_back("-check-hash"); + + llvm::SmallString<128> StdErrPath; + int StdErrFD = -1; + if (std::error_code EC = sys::fs::createTemporaryFile( + "llvm-cas-validate-stderr", "txt", StdErrFD, StdErrPath, + llvm::sys::fs::OF_Text)) + return createStringError(EC, "failed to create temporary file"); + FileRemover OutputRemover(StdErrPath.c_str()); + + std::optional<llvm::StringRef> Redirects[] = { + {""}, // stdin = /dev/null + {""}, // stdout = /dev/null + StdErrPath.str(), + }; + + std::string ErrMsg; + int Result = + sys::ExecuteAndWait(LLVMCasBinary, Args, /*Env=*/std::nullopt, Redirects, + /*SecondsToWait=*/120, /*MemoryLimit=*/0, &ErrMsg); + + if (Result == -1) + return createStringError("failed to exec " + join(Args, " ") + ": " + + ErrMsg); + if (Result != 0) { + llvm::SmallString<64> Err("cas contents invalid"); + if (!ErrMsg.empty()) { + Err += ": "; + Err += ErrMsg; + } + auto StdErrBuf = MemoryBuffer::getFile(StdErrPath.c_str()); + if (StdErrBuf && !(*StdErrBuf)->getBuffer().empty()) { + Err += ": "; + Err += (*StdErrBuf)->getBuffer(); + } + return createStringError(Err); + } + return Error::success(); +} + +static Error validateInProcess(StringRef RootPath, StringRef HashName, + unsigned HashByteSize, bool CheckHash) { + std::shared_ptr<UnifiedOnDiskCache> UniDB; + if (Error E = UnifiedOnDiskCache::open(RootPath, std::nullopt, HashName, + HashByteSize) + .moveInto(UniDB)) + return E; + auto CAS = builtin::createObjectStoreFromUnifiedOnDiskCache(UniDB); + if (Error E = CAS->validate(CheckHash)) + return E; + auto Cache = builtin::createActionCacheFromUnifiedOnDiskCache(UniDB); + if (Error E = Cache->validate()) + return E; + return Error::success(); +} + +static Expected<uint64_t> getBootTime() { +#if __has_include(<sys/sysctl.h>) && defined(KERN_BOOTTIME) + struct timeval TV; + size_t TVLen = sizeof(TV); + int KernBoot[2] = {CTL_KERN, KERN_BOOTTIME}; + if (sysctl(KernBoot, 2, &TV, &TVLen, nullptr, 0) < 0) + return createStringError(llvm::errnoAsErrorCode(), + "failed to get boottime"); + if (TVLen != sizeof(TV)) + return createStringError("sysctl kern.boottime unexpected format"); + return TV.tv_sec; +#elif defined(__linux__) + // Use the mtime for /proc, which is recreated during system boot. + // We could also read /proc/stat and search for 'btime'. + sys::fs::file_status Status; + if (std::error_code EC = sys::fs::status("/proc", Status)) + return createFileError("/proc", EC); + return Status.getLastModificationTime().time_since_epoch().count(); +#else + llvm::report_fatal_error("getBootTime unimplemented"); +#endif +} + +Expected<ValidationResult> UnifiedOnDiskCache::validateIfNeeded( + StringRef RootPath, StringRef HashName, unsigned HashByteSize, + bool CheckHash, bool AllowRecovery, bool ForceValidation, + std::optional<StringRef> LLVMCasBinaryPath) { + if (std::error_code EC = sys::fs::create_directories(RootPath)) + return createFileError(RootPath, EC); + + SmallString<256> PathBuf(RootPath); + sys::path::append(PathBuf, ValidationFilename); + int FD = -1; + if (std::error_code EC = sys::fs::openFileForReadWrite( + PathBuf, FD, sys::fs::CD_OpenAlways, sys::fs::OF_None)) + return createFileError(PathBuf, EC); + assert(FD != -1); + + sys::fs::file_t File = sys::fs::convertFDToNativeFile(FD); + auto CloseFile = make_scope_exit([&]() { sys::fs::closeFile(File); }); + + if (std::error_code EC = lockFileThreadSafe(FD, sys::fs::LockKind::Exclusive)) + return createFileError(PathBuf, EC); + auto UnlockFD = make_scope_exit([&]() { unlockFileThreadSafe(FD); }); + + SmallString<8> Bytes; + if (Error E = sys::fs::readNativeFileToEOF(File, Bytes)) + return createFileError(PathBuf, std::move(E)); + + uint64_t ValidationBootTime = 0; + if (!Bytes.empty() && + StringRef(Bytes).trim().getAsInteger(10, ValidationBootTime)) + return createFileError(PathBuf, errc::illegal_byte_sequence, + "expected integer"); + + static uint64_t BootTime = 0; + if (BootTime == 0) + if (Error E = getBootTime().moveInto(BootTime)) + return std::move(E); + + std::string LogValidationError; + + if (ValidationBootTime == BootTime && !ForceValidation) + return ValidationResult::Skipped; + + // Validate! + bool NeedsRecovery = false; + if (Error E = + LLVMCasBinaryPath + ? validateOutOfProcess(*LLVMCasBinaryPath, RootPath, CheckHash) + : validateInProcess(RootPath, HashName, HashByteSize, + CheckHash)) { + if (AllowRecovery) { + consumeError(std::move(E)); + NeedsRecovery = true; + } else { + return std::move(E); + } + } + + if (NeedsRecovery) { + sys::path::remove_filename(PathBuf); + sys::path::append(PathBuf, "lock"); + + int LockFD = -1; + if (std::error_code EC = sys::fs::openFileForReadWrite( + PathBuf, LockFD, sys::fs::CD_OpenAlways, sys::fs::OF_None)) + return createFileError(PathBuf, EC); + sys::fs::file_t LockFile = sys::fs::convertFDToNativeFile(LockFD); + auto CloseLock = make_scope_exit([&]() { sys::fs::closeFile(LockFile); }); + if (std::error_code EC = tryLockFileThreadSafe(LockFD)) { + if (EC == std::errc::no_lock_available) + return createFileError( + PathBuf, EC, + "CAS validation requires exclusive access but CAS was in use"); + return createFileError(PathBuf, EC); + } + auto UnlockFD = make_scope_exit([&]() { unlockFileThreadSafe(LockFD); }); + + auto DBDirs = getAllDBDirs(RootPath); + if (!DBDirs) + return DBDirs.takeError(); + + for (StringRef DBDir : *DBDirs) { + sys::path::remove_filename(PathBuf); + sys::path::append(PathBuf, DBDir); + std::error_code EC; + int Attempt = 0, MaxAttempts = 100; + SmallString<128> GCPath; + for (; Attempt < MaxAttempts; ++Attempt) { + GCPath.assign(RootPath); + sys::path::append(GCPath, CorruptPrefix + std::to_string(Attempt) + + "." + DBDir); + EC = sys::fs::rename(PathBuf, GCPath); + // Darwin uses ENOTEMPTY. Linux may return either ENOTEMPTY or EEXIST. + if (EC != errc::directory_not_empty && EC != errc::file_exists) + break; + } + if (Attempt == MaxAttempts) + return createStringError( + EC, "rename " + PathBuf + + " failed: too many CAS directories awaiting pruning"); + if (EC) + return createStringError(EC, "rename " + PathBuf + " to " + GCPath + + " failed: " + EC.message()); + } + } + + if (ValidationBootTime != BootTime) { + // Fix filename in case we have error to report. + sys::path::remove_filename(PathBuf); + sys::path::append(PathBuf, ValidationFilename); + if (std::error_code EC = sys::fs::resize_file(FD, 0)) + return createFileError(PathBuf, EC); + raw_fd_ostream OS(FD, /*shouldClose=*/false); + OS.seek(0); // resize does not reset position + OS << BootTime << '\n'; + if (OS.has_error()) + return createFileError(PathBuf, OS.error()); + } + + return NeedsRecovery ? ValidationResult::Recovered : ValidationResult::Valid; +} + +Expected<std::unique_ptr<UnifiedOnDiskCache>> +UnifiedOnDiskCache::open(StringRef RootPath, std::optional<uint64_t> SizeLimit, + StringRef HashName, unsigned HashByteSize, + OnDiskGraphDB::FaultInPolicy FaultInPolicy) { + if (std::error_code EC = sys::fs::create_directories(RootPath)) + return createFileError(RootPath, EC); + + SmallString<256> PathBuf(RootPath); + sys::path::append(PathBuf, "lock"); + int LockFD = -1; + if (std::error_code EC = sys::fs::openFileForReadWrite( + PathBuf, LockFD, sys::fs::CD_OpenAlways, sys::fs::OF_None)) + return createFileError(PathBuf, EC); + assert(LockFD != -1); + // Locking the directory using shared lock, which will prevent other processes + // from creating a new chain (essentially while a \p UnifiedOnDiskCache + // instance holds a shared lock the storage for the primary directory will + // grow unrestricted). + if (std::error_code EC = + lockFileThreadSafe(LockFD, sys::fs::LockKind::Shared)) + return createFileError(PathBuf, EC); + + auto DBDirs = getAllDBDirs(RootPath); + if (!DBDirs) + return DBDirs.takeError(); + if (DBDirs->empty()) + DBDirs->push_back((Twine(DBDirPrefix) + "1").str()); + + assert(!DBDirs->empty()); + + /// If there is only one directory open databases on it. If there are 2 or + /// more directories, get the most recent directories and chain them, with the + /// most recent being the primary one. The remaining directories are unused + /// data than can be garbage-collected. + auto UniDB = std::unique_ptr<UnifiedOnDiskCache>(new UnifiedOnDiskCache()); + std::unique_ptr<OnDiskGraphDB> UpstreamGraphDB; + std::unique_ptr<OnDiskKeyValueDB> UpstreamKVDB; + if (DBDirs->size() > 1) { + StringRef UpstreamDir = *(DBDirs->end() - 2); + PathBuf = RootPath; + sys::path::append(PathBuf, UpstreamDir); + if (Error E = OnDiskGraphDB::open(PathBuf, HashName, HashByteSize, + /*UpstreamDB=*/nullptr, FaultInPolicy) + .moveInto(UpstreamGraphDB)) + return std::move(E); + if (Error E = OnDiskKeyValueDB::open(PathBuf, HashName, HashByteSize, + /*ValueName=*/"objectid", + /*ValueSize=*/sizeof(uint64_t)) + .moveInto(UpstreamKVDB)) + return std::move(E); + } + + StringRef PrimaryDir = *(DBDirs->end() - 1); + PathBuf = RootPath; + sys::path::append(PathBuf, PrimaryDir); + std::unique_ptr<OnDiskGraphDB> PrimaryGraphDB; + if (Error E = OnDiskGraphDB::open(PathBuf, HashName, HashByteSize, + UpstreamGraphDB.get(), FaultInPolicy) + .moveInto(PrimaryGraphDB)) + return std::move(E); + std::unique_ptr<OnDiskKeyValueDB> PrimaryKVDB; + // \p UnifiedOnDiskCache does manual chaining for key-value requests, + // including an extra translation step of the value during fault-in. + if (Error E = + OnDiskKeyValueDB::open(PathBuf, HashName, HashByteSize, + /*ValueName=*/"objectid", + /*ValueSize=*/sizeof(uint64_t), UniDB.get()) + .moveInto(PrimaryKVDB)) + return std::move(E); + + UniDB->RootPath = RootPath; + UniDB->SizeLimit = SizeLimit.value_or(0); + UniDB->LockFD = LockFD; + UniDB->NeedsGarbageCollection = DBDirs->size() > 2; + UniDB->PrimaryDBDir = PrimaryDir; + UniDB->UpstreamGraphDB = std::move(UpstreamGraphDB); + UniDB->PrimaryGraphDB = std::move(PrimaryGraphDB); + UniDB->UpstreamKVDB = std::move(UpstreamKVDB); + UniDB->PrimaryKVDB = std::move(PrimaryKVDB); + + return std::move(UniDB); +} + +void UnifiedOnDiskCache::setSizeLimit(std::optional<uint64_t> SizeLimit) { + this->SizeLimit = SizeLimit.value_or(0); +} + +uint64_t UnifiedOnDiskCache::getStorageSize() const { + uint64_t TotalSize = getPrimaryStorageSize(); + if (UpstreamGraphDB) + TotalSize += UpstreamGraphDB->getStorageSize(); + if (UpstreamKVDB) + TotalSize += UpstreamKVDB->getStorageSize(); + return TotalSize; +} + +uint64_t UnifiedOnDiskCache::getPrimaryStorageSize() const { + return PrimaryGraphDB->getStorageSize() + PrimaryKVDB->getStorageSize(); +} + +bool UnifiedOnDiskCache::hasExceededSizeLimit() const { + uint64_t CurSizeLimit = SizeLimit; + if (!CurSizeLimit) + return false; + + // If the hard limit is beyond 85%, declare above limit and request clean up. + unsigned CurrentPercent = + std::max(PrimaryGraphDB->getHardStorageLimitUtilization(), + PrimaryKVDB->getHardStorageLimitUtilization()); + if (CurrentPercent > 85) + return true; + + // We allow each of the directories in the chain to reach up to half the + // intended size limit. Check whether the primary directory has exceeded half + // the limit or not, in order to decide whether we need to start a new chain. + // + // We could check the size limit against the sum of sizes of both the primary + // and upstream directories but then if the upstream is significantly larger + // than the intended limit, it would trigger a new chain to be created before + // the primary has reached its own limit. Essentially in such situation we + // prefer reclaiming the storage later in order to have more consistent cache + // hits behavior. + return (CurSizeLimit / 2) < getPrimaryStorageSize(); +} + +Error UnifiedOnDiskCache::close(bool CheckSizeLimit) { + if (LockFD == -1) + return Error::success(); // already closed. + auto CloseLock = make_scope_exit([&]() { + assert(LockFD >= 0); + sys::fs::file_t LockFile = sys::fs::convertFDToNativeFile(LockFD); + sys::fs::closeFile(LockFile); + LockFD = -1; + }); + + bool ExceededSizeLimit = CheckSizeLimit ? hasExceededSizeLimit() : false; + UpstreamKVDB.reset(); + PrimaryKVDB.reset(); + UpstreamGraphDB.reset(); + PrimaryGraphDB.reset(); + if (std::error_code EC = unlockFileThreadSafe(LockFD)) + return createFileError(RootPath, EC); + + if (!ExceededSizeLimit) + return Error::success(); + + // The primary directory exceeded its intended size limit. Try to get an + // exclusive lock in order to create a new primary directory for next time + // this \p UnifiedOnDiskCache path is opened. + + if (std::error_code EC = tryLockFileThreadSafe( + LockFD, std::chrono::milliseconds(0), sys::fs::LockKind::Exclusive)) { + if (EC == errc::no_lock_available) + return Error::success(); // couldn't get exclusive lock, give up. + return createFileError(RootPath, EC); + } + auto UnlockFile = make_scope_exit([&]() { unlockFileThreadSafe(LockFD); }); + + // Managed to get an exclusive lock which means there are no other open + // \p UnifiedOnDiskCache instances for the same path, so we can safely start a + // new primary directory. To start a new primary directory we just have to + // create a new empty directory with the next consecutive index; since this is + // an atomic operation we will leave the top-level directory in a consistent + // state even if the process dies during this code-path. + + SmallString<256> PathBuf(RootPath); + raw_svector_ostream OS(PathBuf); + OS << sys::path::get_separator(); + getNextDBDirName(PrimaryDBDir, OS); + if (std::error_code EC = sys::fs::create_directory(PathBuf)) + return createFileError(PathBuf, EC); + + NeedsGarbageCollection = true; + return Error::success(); +} + +UnifiedOnDiskCache::UnifiedOnDiskCache() = default; + +UnifiedOnDiskCache::~UnifiedOnDiskCache() { consumeError(close()); } + +Error UnifiedOnDiskCache::collectGarbage(StringRef Path) { + auto DBDirs = getAllGarbageDirs(Path); + if (!DBDirs) + return DBDirs.takeError(); + + SmallString<256> PathBuf(Path); + for (StringRef UnusedSubDir : *DBDirs) { + sys::path::append(PathBuf, UnusedSubDir); + if (std::error_code EC = sys::fs::remove_directories(PathBuf)) + return createFileError(PathBuf, EC); + sys::path::remove_filename(PathBuf); + } + return Error::success(); +} + +Error UnifiedOnDiskCache::collectGarbage() { return collectGarbage(RootPath); } |