diff options
Diffstat (limited to 'third_party/nix/src/libstore/gc.cc')
| -rw-r--r-- | third_party/nix/src/libstore/gc.cc | 997 |
1 files changed, 0 insertions, 997 deletions
diff --git a/third_party/nix/src/libstore/gc.cc b/third_party/nix/src/libstore/gc.cc deleted file mode 100644 index 07dc10629a..0000000000 --- a/third_party/nix/src/libstore/gc.cc +++ /dev/null @@ -1,997 +0,0 @@ -#include <algorithm> -#include <cerrno> -#include <climits> -#include <functional> -#include <queue> -#include <random> -#include <regex> - -#include <absl/strings/match.h> -#include <absl/strings/str_cat.h> -#include <absl/strings/str_split.h> -#include <fcntl.h> -#include <glog/logging.h> -#include <sys/stat.h> -#include <sys/statvfs.h> -#include <sys/types.h> -#include <unistd.h> - -#include "libstore/derivations.hh" -#include "libstore/globals.hh" -#include "libstore/local-store.hh" -#include "libutil/finally.hh" - -namespace nix { - -constexpr std::string_view kGcLockName = "gc.lock"; -constexpr std::string_view kGcRootsDir = "gcroots"; - -/* Acquire the global GC lock. This is used to prevent new Nix - processes from starting after the temporary root files have been - read. To be precise: when they try to create a new temporary root - file, they will block until the garbage collector has finished / - yielded the GC lock. */ -AutoCloseFD LocalStore::openGCLock(LockType lockType) { - Path fnGCLock = absl::StrCat(stateDir.get(), "/", kGcLockName); - - DLOG(INFO) << "acquiring global GC lock " << fnGCLock; - - AutoCloseFD fdGCLock( - open(fnGCLock.c_str(), O_RDWR | O_CREAT | O_CLOEXEC, 0600)); - - if (!fdGCLock) { - throw SysError(format("opening global GC lock '%1%'") % fnGCLock); - } - - if (!lockFile(fdGCLock.get(), lockType, false)) { - LOG(ERROR) << "waiting for the big garbage collector lock..."; - lockFile(fdGCLock.get(), lockType, true); - } - - /* !!! Restrict read permission on the GC root. Otherwise any - process that can open the file for reading can DoS the - collector. */ - - return fdGCLock; -} - -static void makeSymlink(const Path& link, const Path& target) { - /* Create directories up to `gcRoot'. */ - createDirs(dirOf(link)); - - /* Create the new symlink. */ - Path tempLink = - (format("%1%.tmp-%2%-%3%") % link % getpid() % random()).str(); - createSymlink(target, tempLink); - - /* Atomically replace the old one. */ - if (rename(tempLink.c_str(), link.c_str()) == -1) { - throw SysError(format("cannot rename '%1%' to '%2%'") % tempLink % link); - } -} - -void LocalStore::syncWithGC() { AutoCloseFD fdGCLock = openGCLock(ltRead); } - -void LocalStore::addIndirectRoot(const Path& path) { - std::string hash = hashString(htSHA1, path).to_string(Base32, false); - Path realRoot = - canonPath(absl::StrCat(stateDir.get(), "/", kGcRootsDir, "/auto/", hash)); - makeSymlink(realRoot, path); -} - -Path LocalFSStore::addPermRoot(const Path& _storePath, const Path& _gcRoot, - bool indirect, bool allowOutsideRootsDir) { - Path storePath(canonPath(_storePath)); - Path gcRoot(canonPath(_gcRoot)); - assertStorePath(storePath); - - if (isInStore(gcRoot)) { - throw Error(format("creating a garbage collector root (%1%) in the Nix " - "store is forbidden " - "(are you running nix-build inside the store?)") % - gcRoot); - } - - if (indirect) { - /* Don't clobber the link if it already exists and doesn't - point to the Nix store. */ - if (pathExists(gcRoot) && - (!isLink(gcRoot) || !isInStore(readLink(gcRoot)))) { - throw Error(format("cannot create symlink '%1%'; already exists") % - gcRoot); - } - makeSymlink(gcRoot, storePath); - addIndirectRoot(gcRoot); - } - - else { - if (!allowOutsideRootsDir) { - Path rootsDir = canonPath(absl::StrCat(stateDir.get(), "/", kGcRootsDir)); - - if (std::string(gcRoot, 0, rootsDir.size() + 1) != rootsDir + "/") { - throw Error(format("path '%1%' is not a valid garbage collector root; " - "it's not in the directory '%2%'") % - gcRoot % rootsDir); - } - } - - if (baseNameOf(gcRoot) == baseNameOf(storePath)) { - writeFile(gcRoot, ""); - } else { - makeSymlink(gcRoot, storePath); - } - } - - /* Check that the root can be found by the garbage collector. - !!! This can be very slow on machines that have many roots. - Instead of reading all the roots, it would be more efficient to - check if the root is in a directory in or linked from the - gcroots directory. */ - if (settings.checkRootReachability) { - Roots roots = findRoots(false); - if (roots[storePath].count(gcRoot) == 0) { - LOG(ERROR) << "warning: '" << gcRoot - << "' is not in a directory where the garbage " - << "collector looks for roots; therefore, '" << storePath - << "' might be removed by the garbage collector"; - } - } - - /* Grab the global GC root, causing us to block while a GC is in - progress. This prevents the set of permanent roots from - increasing while a GC is in progress. */ - syncWithGC(); - - return gcRoot; -} - -void LocalStore::addTempRoot(const Path& path) { - auto state(_state.lock()); - - /* Create the temporary roots file for this process. */ - if (!state->fdTempRoots) { - while (true) { - AutoCloseFD fdGCLock = openGCLock(ltRead); - - if (pathExists(fnTempRoots)) { - /* It *must* be stale, since there can be no two - processes with the same pid. */ - unlink(fnTempRoots.c_str()); - } - - state->fdTempRoots = openLockFile(fnTempRoots, true); - - fdGCLock = AutoCloseFD(-1); - - DLOG(INFO) << "acquiring read lock on " << fnTempRoots; - lockFile(state->fdTempRoots.get(), ltRead, true); - - /* Check whether the garbage collector didn't get in our - way. */ - struct stat st; - if (fstat(state->fdTempRoots.get(), &st) == -1) { - throw SysError(format("statting '%1%'") % fnTempRoots); - } - if (st.st_size == 0) { - break; - } - - /* The garbage collector deleted this file before we could - get a lock. (It won't delete the file after we get a - lock.) Try again. */ - } - } - - /* Upgrade the lock to a write lock. This will cause us to block - if the garbage collector is holding our lock. */ - DLOG(INFO) << "acquiring write lock on " << fnTempRoots; - lockFile(state->fdTempRoots.get(), ltWrite, true); - - std::string s = path + '\0'; - writeFull(state->fdTempRoots.get(), s); - - /* Downgrade to a read lock. */ - DLOG(INFO) << "downgrading to read lock on " << fnTempRoots; - lockFile(state->fdTempRoots.get(), ltRead, true); -} - -constexpr std::string_view kCensored = "{censored}"; - -void LocalStore::findTempRoots(FDs& fds, Roots& tempRoots, bool censor) { - /* Read the `temproots' directory for per-process temporary root - files. */ - for (auto& i : readDirectory(tempRootsDir)) { - Path path = tempRootsDir + "/" + i.name; - - pid_t pid = std::stoi(i.name); - - DLOG(INFO) << "reading temporary root file " << path; - FDPtr fd(new AutoCloseFD(open(path.c_str(), O_CLOEXEC | O_RDWR, 0666))); - if (!*fd) { - /* It's okay if the file has disappeared. */ - if (errno == ENOENT) { - continue; - } - throw SysError(format("opening temporary roots file '%1%'") % path); - } - - /* This should work, but doesn't, for some reason. */ - // FDPtr fd(new AutoCloseFD(openLockFile(path, false))); - // if (*fd == -1) { continue; } - - /* Try to acquire a write lock without blocking. This can - only succeed if the owning process has died. In that case - we don't care about its temporary roots. */ - if (lockFile(fd->get(), ltWrite, false)) { - LOG(ERROR) << "removing stale temporary roots file " << path; - unlink(path.c_str()); - writeFull(fd->get(), "d"); - continue; - } - - /* Acquire a read lock. This will prevent the owning process - from upgrading to a write lock, therefore it will block in - addTempRoot(). */ - DLOG(INFO) << "waiting for read lock on " << path; - lockFile(fd->get(), ltRead, true); - - /* Read the entire file. */ - std::string contents = readFile(fd->get()); - - /* Extract the roots. */ - std::string::size_type pos = 0; - std::string::size_type end; - - while ((end = contents.find(static_cast<char>(0), pos)) != - std::string::npos) { - Path root(contents, pos, end - pos); - DLOG(INFO) << "got temporary root " << root; - assertStorePath(root); - tempRoots[root].emplace(censor ? kCensored : fmt("{temp:%d}", pid)); - pos = end + 1; - } - - fds.push_back(fd); /* keep open */ - } -} - -void LocalStore::findRoots(const Path& path, unsigned char type, Roots& roots) { - auto foundRoot = [&](const Path& path, const Path& target) { - Path storePath = toStorePath(target); - if (isStorePath(storePath) && isValidPath(storePath)) { - roots[storePath].emplace(path); - } else { - LOG(INFO) << "skipping invalid root from '" << path << "' to '" - << storePath << "'"; - } - }; - - try { - if (type == DT_UNKNOWN) { - type = getFileType(path); - } - - if (type == DT_DIR) { - for (auto& i : readDirectory(path)) { - findRoots(path + "/" + i.name, i.type, roots); - } - } - - else if (type == DT_LNK) { - Path target = readLink(path); - if (isInStore(target)) { - foundRoot(path, target); - } - - /* Handle indirect roots. */ - else { - target = absPath(target, dirOf(path)); - if (!pathExists(target)) { - if (isInDir(path, absl::StrCat(stateDir.get(), "/", kGcRootsDir, - "/auto"))) { - LOG(INFO) << "removing stale link from '" << path << "' to '" - << target << "'"; - unlink(path.c_str()); - } - } else { - struct stat st2 = lstat(target); - if (!S_ISLNK(st2.st_mode)) { - return; - } - Path target2 = readLink(target); - if (isInStore(target2)) { - foundRoot(target, target2); - } - } - } - } - - else if (type == DT_REG) { - Path storePath = storeDir + "/" + baseNameOf(path); - if (isStorePath(storePath) && isValidPath(storePath)) { - roots[storePath].emplace(path); - } - } - - } - - catch (SysError& e) { - /* We only ignore permanent failures. */ - if (e.errNo == EACCES || e.errNo == ENOENT || e.errNo == ENOTDIR) { - LOG(INFO) << "cannot read potential root '" << path << "'"; - } else { - throw; - } - } -} - -void LocalStore::findRootsNoTemp(Roots& roots, bool censor) { - /* Process direct roots in {gcroots,profiles}. */ - findRoots(absl::StrCat(stateDir.get(), "/", kGcRootsDir), DT_UNKNOWN, roots); - findRoots(stateDir + "/profiles", DT_UNKNOWN, roots); - - /* Add additional roots returned by different platforms-specific - heuristics. This is typically used to add running programs to - the set of roots (to prevent them from being garbage collected). */ - findRuntimeRoots(roots, censor); -} - -Roots LocalStore::findRoots(bool censor) { - Roots roots; - findRootsNoTemp(roots, censor); - - FDs fds; - findTempRoots(fds, roots, censor); - - return roots; -} - -static void readProcLink(const std::string& file, Roots& roots) { - /* 64 is the starting buffer size gnu readlink uses... */ - auto bufsiz = ssize_t{64}; -try_again: - char buf[bufsiz]; - auto res = readlink(file.c_str(), buf, bufsiz); - if (res == -1) { - if (errno == ENOENT || errno == EACCES || errno == ESRCH) { - return; - } - throw SysError("reading symlink"); - } - if (res == bufsiz) { - if (SSIZE_MAX / 2 < bufsiz) { - throw Error("stupidly long symlink"); - } - bufsiz *= 2; - goto try_again; - } - if (res > 0 && buf[0] == '/') { - roots[std::string(static_cast<char*>(buf), res)].emplace(file); - } -} - -static std::string quoteRegexChars(const std::string& raw) { - static auto specialRegex = std::regex(R"([.^$\\*+?()\[\]{}|])"); - return std::regex_replace(raw, specialRegex, R"(\$&)"); -} - -static void readFileRoots(const char* path, Roots& roots) { - try { - roots[readFile(path)].emplace(path); - } catch (SysError& e) { - if (e.errNo != ENOENT && e.errNo != EACCES) { - throw; - } - } -} - -void LocalStore::findRuntimeRoots(Roots& roots, bool censor) { - Roots unchecked; - - auto procDir = AutoCloseDir{opendir("/proc")}; - if (procDir) { - struct dirent* ent; - auto digitsRegex = std::regex(R"(^\d+$)"); - auto mapRegex = - std::regex(R"(^\s*\S+\s+\S+\s+\S+\s+\S+\s+\S+\s+(/\S+)\s*$)"); - auto storePathRegex = std::regex(quoteRegexChars(storeDir) + - R"(/[0-9a-z]+[0-9a-zA-Z\+\-\._\?=]*)"); - while (errno = 0, ent = readdir(procDir.get())) { - checkInterrupt(); - if (std::regex_match(ent->d_name, digitsRegex)) { - readProcLink(fmt("/proc/%s/exe", ent->d_name), unchecked); - readProcLink(fmt("/proc/%s/cwd", ent->d_name), unchecked); - - auto fdStr = fmt("/proc/%s/fd", ent->d_name); - auto fdDir = AutoCloseDir(opendir(fdStr.c_str())); - if (!fdDir) { - if (errno == ENOENT || errno == EACCES) { - continue; - } - throw SysError(format("opening %1%") % fdStr); - } - struct dirent* fd_ent; - while (errno = 0, fd_ent = readdir(fdDir.get())) { - if (fd_ent->d_name[0] != '.') { - readProcLink(fmt("%s/%s", fdStr, fd_ent->d_name), unchecked); - } - } - if (errno) { - if (errno == ESRCH) { - continue; - } - throw SysError(format("iterating /proc/%1%/fd") % ent->d_name); - } - fdDir.reset(); - - try { - auto mapFile = fmt("/proc/%s/maps", ent->d_name); - std::vector<std::string> mapLines = absl::StrSplit( - readFile(mapFile, true), absl::ByChar('\n'), absl::SkipEmpty()); - for (const auto& line : mapLines) { - auto match = std::smatch{}; - if (std::regex_match(line, match, mapRegex)) { - unchecked[match[1]].emplace(mapFile); - } - } - - auto envFile = fmt("/proc/%s/environ", ent->d_name); - auto envString = readFile(envFile, true); - auto env_end = std::sregex_iterator{}; - for (auto i = std::sregex_iterator{envString.begin(), envString.end(), - storePathRegex}; - i != env_end; ++i) { - unchecked[i->str()].emplace(envFile); - } - } catch (SysError& e) { - if (errno == ENOENT || errno == EACCES || errno == ESRCH) { - continue; - } - throw; - } - } - } - if (errno) { - throw SysError("iterating /proc"); - } - } - - readFileRoots("/proc/sys/kernel/modprobe", unchecked); - readFileRoots("/proc/sys/kernel/fbsplash", unchecked); - readFileRoots("/proc/sys/kernel/poweroff_cmd", unchecked); - - for (auto& [target, links] : unchecked) { - if (isInStore(target)) { - Path path = toStorePath(target); - if (isStorePath(path) && isValidPath(path)) { - DLOG(INFO) << "got additional root " << path; - if (censor) { - roots[path].insert(std::string(kCensored)); - } else { - roots[path].insert(links.begin(), links.end()); - } - } - } - } -} - -struct GCLimitReached {}; - -struct LocalStore::GCState { - GCOptions options; - GCResults& results; - PathSet roots; - PathSet tempRoots; - PathSet dead; - PathSet alive; - bool gcKeepOutputs; - bool gcKeepDerivations; - unsigned long long bytesInvalidated; - bool moveToTrash = true; - bool shouldDelete; - explicit GCState(GCResults& results_) - : results(results_), bytesInvalidated(0) {} -}; - -bool LocalStore::isActiveTempFile(const GCState& state, const Path& path, - const std::string& suffix) { - return absl::EndsWith(path, suffix) && - state.tempRoots.find(std::string( - path, 0, path.size() - suffix.size())) != state.tempRoots.end(); -} - -void LocalStore::deleteGarbage(GCState& state, const Path& path) { - unsigned long long bytesFreed; - deletePath(path, bytesFreed); - state.results.bytesFreed += bytesFreed; -} - -void LocalStore::deletePathRecursive(GCState& state, const Path& path) { - checkInterrupt(); - - unsigned long long size = 0; - - if (isStorePath(path) && isValidPath(path)) { - PathSet referrers; - queryReferrers(path, referrers); - for (auto& i : referrers) { - if (i != path) { - deletePathRecursive(state, i); - } - } - size = queryPathInfo(path)->narSize; - invalidatePathChecked(path); - } - - Path realPath = realStoreDir + "/" + baseNameOf(path); - - struct stat st; - if (lstat(realPath.c_str(), &st) != 0) { - if (errno == ENOENT) { - return; - } - throw SysError(format("getting status of %1%") % realPath); - } - - LOG(INFO) << "deleting '" << path << "'"; - - state.results.paths.insert(path); - - /* If the path is not a regular file or symlink, move it to the - trash directory. The move is to ensure that later (when we're - not holding the global GC lock) we can delete the path without - being afraid that the path has become alive again. Otherwise - delete it right away. */ - if (state.moveToTrash && S_ISDIR(st.st_mode)) { - // Estimate the amount freed using the narSize field. FIXME: - // if the path was not valid, need to determine the actual - // size. - try { - if (chmod(realPath.c_str(), st.st_mode | S_IWUSR) == -1) { - throw SysError(format("making '%1%' writable") % realPath); - } - Path tmp = trashDir + "/" + baseNameOf(path); - if (rename(realPath.c_str(), tmp.c_str()) != 0) { - throw SysError(format("unable to rename '%1%' to '%2%'") % realPath % - tmp); - } - state.bytesInvalidated += size; - } catch (SysError& e) { - if (e.errNo == ENOSPC) { - LOG(INFO) << "note: can't create move '" << realPath - << "': " << e.msg(); - deleteGarbage(state, realPath); - } - } - } else { - deleteGarbage(state, realPath); - } - - if (state.results.bytesFreed + state.bytesInvalidated > - state.options.maxFreed) { - LOG(INFO) << "deleted or invalidated more than " << state.options.maxFreed - << " bytes; stopping"; - throw GCLimitReached(); - } -} - -bool LocalStore::canReachRoot(GCState& state, PathSet& visited, - const Path& path) { - if (visited.count(path) != 0u) { - return false; - } - - if (state.alive.count(path) != 0u) { - return true; - } - - if (state.dead.count(path) != 0u) { - return false; - } - - if (state.roots.count(path) != 0u) { - DLOG(INFO) << "cannot delete '" << path << "' because it's a root"; - state.alive.insert(path); - return true; - } - - visited.insert(path); - - if (!isStorePath(path) || !isValidPath(path)) { - return false; - } - - PathSet incoming; - - /* Don't delete this path if any of its referrers are alive. */ - queryReferrers(path, incoming); - - /* If keep-derivations is set and this is a derivation, then - don't delete the derivation if any of the outputs are alive. */ - if (state.gcKeepDerivations && isDerivation(path)) { - PathSet outputs = queryDerivationOutputs(path); - for (auto& i : outputs) { - if (isValidPath(i) && queryPathInfo(i)->deriver == path) { - incoming.insert(i); - } - } - } - - /* If keep-outputs is set, then don't delete this path if there - are derivers of this path that are not garbage. */ - if (state.gcKeepOutputs) { - PathSet derivers = queryValidDerivers(path); - for (auto& i : derivers) { - incoming.insert(i); - } - } - - for (auto& i : incoming) { - if (i != path) { - if (canReachRoot(state, visited, i)) { - state.alive.insert(path); - return true; - } - } - } - - return false; -} - -void LocalStore::tryToDelete(GCState& state, const Path& path) { - checkInterrupt(); - - auto realPath = realStoreDir + "/" + baseNameOf(path); - if (realPath == linksDir || realPath == trashDir) { - return; - } - - // Activity act(*logger, lvlDebug, format("considering whether to delete - // '%1%'") % path); - - if (!isStorePath(path) || !isValidPath(path)) { - /* A lock file belonging to a path that we're building right - now isn't garbage. */ - if (isActiveTempFile(state, path, ".lock")) { - return; - } - - /* Don't delete .chroot directories for derivations that are - currently being built. */ - if (isActiveTempFile(state, path, ".chroot")) { - return; - } - - /* Don't delete .check directories for derivations that are - currently being built, because we may need to run - diff-hook. */ - if (isActiveTempFile(state, path, ".check")) { - return; - } - } - - PathSet visited; - - if (canReachRoot(state, visited, path)) { - DLOG(INFO) << "cannot delete '" << path << "' because it's still reachable"; - } else { - /* No path we visited was a root, so everything is garbage. - But we only delete ‘path’ and its referrers here so that - ‘nix-store --delete’ doesn't have the unexpected effect of - recursing into derivations and outputs. */ - state.dead.insert(visited.begin(), visited.end()); - if (state.shouldDelete) { - deletePathRecursive(state, path); - } - } -} - -/* Unlink all files in /nix/store/.links that have a link count of 1, - which indicates that there are no other links and so they can be - safely deleted. FIXME: race condition with optimisePath(): we - might see a link count of 1 just before optimisePath() increases - the link count. */ -void LocalStore::removeUnusedLinks(const GCState& state) { - AutoCloseDir dir(opendir(linksDir.c_str())); - if (!dir) { - throw SysError(format("opening directory '%1%'") % linksDir); - } - - long long actualSize = 0; - long long unsharedSize = 0; - - struct dirent* dirent; - while (errno = 0, dirent = readdir(dir.get())) { - checkInterrupt(); - std::string name = dirent->d_name; - if (name == "." || name == "..") { - continue; - } - Path path = linksDir + "/" + name; - - struct stat st; - if (lstat(path.c_str(), &st) == -1) { - throw SysError(format("statting '%1%'") % path); - } - - if (st.st_nlink != 1) { - actualSize += st.st_size; - unsharedSize += (st.st_nlink - 1) * st.st_size; - continue; - } - - LOG(INFO) << "deleting unused link " << path; - - if (unlink(path.c_str()) == -1) { - throw SysError(format("deleting '%1%'") % path); - } - - state.results.bytesFreed += st.st_size; - } - - struct stat st; - if (stat(linksDir.c_str(), &st) == -1) { - throw SysError(format("statting '%1%'") % linksDir); - } - - long long overhead = st.st_blocks * 512ULL; - - // TODO(tazjin): absl::StrFormat %.2f - LOG(INFO) << "note: currently hard linking saves " - << ((unsharedSize - actualSize - overhead) / (1024.0 * 1024.0)) - << " MiB"; -} - -void LocalStore::collectGarbage(const GCOptions& options, GCResults& results) { - GCState state(results); - state.options = options; - state.gcKeepOutputs = settings.gcKeepOutputs; - state.gcKeepDerivations = settings.gcKeepDerivations; - - /* Using `--ignore-liveness' with `--delete' can have unintended - consequences if `keep-outputs' or `keep-derivations' are true - (the garbage collector will recurse into deleting the outputs - or derivers, respectively). So disable them. */ - if (options.action == GCOptions::gcDeleteSpecific && options.ignoreLiveness) { - state.gcKeepOutputs = false; - state.gcKeepDerivations = false; - } - - state.shouldDelete = options.action == GCOptions::gcDeleteDead || - options.action == GCOptions::gcDeleteSpecific; - - if (state.shouldDelete) { - deletePath(reservedPath); - } - - /* Acquire the global GC root. This prevents - a) New roots from being added. - b) Processes from creating new temporary root files. */ - AutoCloseFD fdGCLock = openGCLock(ltWrite); - - /* Find the roots. Since we've grabbed the GC lock, the set of - permanent roots cannot increase now. */ - LOG(INFO) << "finding garbage collector roots..."; - Roots rootMap; - if (!options.ignoreLiveness) { - findRootsNoTemp(rootMap, true); - } - - for (auto& i : rootMap) { - state.roots.insert(i.first); - } - - /* Read the temporary roots. This acquires read locks on all - per-process temporary root files. So after this point no paths - can be added to the set of temporary roots. */ - FDs fds; - Roots tempRoots; - findTempRoots(fds, tempRoots, true); - for (auto& root : tempRoots) { - state.tempRoots.insert(root.first); - } - state.roots.insert(state.tempRoots.begin(), state.tempRoots.end()); - - /* After this point the set of roots or temporary roots cannot - increase, since we hold locks on everything. So everything - that is not reachable from `roots' is garbage. */ - - if (state.shouldDelete) { - if (pathExists(trashDir)) { - deleteGarbage(state, trashDir); - } - try { - createDirs(trashDir); - } catch (SysError& e) { - if (e.errNo == ENOSPC) { - LOG(INFO) << "note: can't create trash directory: " << e.msg(); - state.moveToTrash = false; - } - } - } - - /* Now either delete all garbage paths, or just the specified - paths (for gcDeleteSpecific). */ - - if (options.action == GCOptions::gcDeleteSpecific) { - for (auto& i : options.pathsToDelete) { - assertStorePath(i); - tryToDelete(state, i); - if (state.dead.find(i) == state.dead.end()) { - throw Error(format("cannot delete path '%1%' since it is still alive") % - i); - } - } - - } else if (options.maxFreed > 0) { - if (state.shouldDelete) { - LOG(INFO) << "deleting garbage..."; - } else { - LOG(ERROR) << "determining live/dead paths..."; - } - - try { - AutoCloseDir dir(opendir(realStoreDir.c_str())); - if (!dir) { - throw SysError(format("opening directory '%1%'") % realStoreDir); - } - - /* Read the store and immediately delete all paths that - aren't valid. When using --max-freed etc., deleting - invalid paths is preferred over deleting unreachable - paths, since unreachable paths could become reachable - again. We don't use readDirectory() here so that GCing - can start faster. */ - Paths entries; - struct dirent* dirent; - while (errno = 0, dirent = readdir(dir.get())) { - checkInterrupt(); - std::string name = dirent->d_name; - if (name == "." || name == "..") { - continue; - } - Path path = storeDir + "/" + name; - if (isStorePath(path) && isValidPath(path)) { - entries.push_back(path); - } else { - tryToDelete(state, path); - } - } - - dir.reset(); - - /* Now delete the unreachable valid paths. Randomise the - order in which we delete entries to make the collector - less biased towards deleting paths that come - alphabetically first (e.g. /nix/store/000...). This - matters when using --max-freed etc. */ - std::vector<Path> entries_(entries.begin(), entries.end()); - std::mt19937 gen(1); - std::shuffle(entries_.begin(), entries_.end(), gen); - - for (auto& i : entries_) { - tryToDelete(state, i); - } - - } catch (GCLimitReached& e) { - } - } - - if (state.options.action == GCOptions::gcReturnLive) { - state.results.paths = state.alive; - return; - } - - if (state.options.action == GCOptions::gcReturnDead) { - state.results.paths = state.dead; - return; - } - - /* Allow other processes to add to the store from here on. */ - fdGCLock = AutoCloseFD(-1); - fds.clear(); - - /* Delete the trash directory. */ - LOG(INFO) << "deleting " << trashDir; - deleteGarbage(state, trashDir); - - /* Clean up the links directory. */ - if (options.action == GCOptions::gcDeleteDead || - options.action == GCOptions::gcDeleteSpecific) { - LOG(INFO) << "deleting unused links..."; - removeUnusedLinks(state); - } - - /* While we're at it, vacuum the database. */ - // if (options.action == GCOptions::gcDeleteDead) { vacuumDB(); } -} - -void LocalStore::autoGC(bool sync) { - static auto fakeFreeSpaceFile = - getEnv("_NIX_TEST_FREE_SPACE_FILE").value_or(""); - - auto getAvail = [this]() -> uint64_t { - if (!fakeFreeSpaceFile.empty()) { - return std::stoll(readFile(fakeFreeSpaceFile)); - } - - struct statvfs st; - if (statvfs(realStoreDir.c_str(), &st) != 0) { - throw SysError("getting filesystem info about '%s'", realStoreDir); - } - - return static_cast<uint64_t>(st.f_bavail) * st.f_bsize; - }; - - std::shared_future<void> future; - - { - auto state(_state.lock()); - - if (state->gcRunning) { - future = state->gcFuture; - DLOG(INFO) << "waiting for auto-GC to finish"; - goto sync; - } - - auto now = std::chrono::steady_clock::now(); - - if (now < state->lastGCCheck + - std::chrono::seconds(settings.minFreeCheckInterval)) { - return; - } - - auto avail = getAvail(); - - state->lastGCCheck = now; - - if (avail >= settings.minFree || avail >= settings.maxFree) { - return; - } - - if (avail > state->availAfterGC * 0.97) { - return; - } - - state->gcRunning = true; - - std::promise<void> promise; - future = state->gcFuture = promise.get_future().share(); - - std::thread([promise{std::move(promise)}, this, avail, getAvail]() mutable { - try { - /* Wake up any threads waiting for the auto-GC to finish. */ - Finally wakeup([&]() { - auto state(_state.lock()); - state->gcRunning = false; - state->lastGCCheck = std::chrono::steady_clock::now(); - promise.set_value(); - }); - - GCOptions options; - options.maxFreed = settings.maxFree - avail; - - LOG(INFO) << "running auto-GC to free " << options.maxFreed << " bytes"; - - GCResults results; - - collectGarbage(options, results); - - _state.lock()->availAfterGC = getAvail(); - - } catch (...) { - // FIXME: we could propagate the exception to the - // future, but we don't really care. - ignoreException(); - } - }).detach(); - } - -sync: - // Wait for the future outside of the state lock. - if (sync) { - future.get(); - } -} - -} // namespace nix |