forked from lix-project/lix
Sergei Trofimovich
d58453f72e
Before the change garbage collector was not considering
`.drv` and outputs as alive even if configuration says otherwise.
As a result `nix store gc --dry-run` could visit (and parse)
`.drv` files multiple times (worst case it's quadratic).
It happens because `alive` set was populating only runtime closure
without regard for actual configuration. The change fixes it.
Benchmark: my system has about 139MB, 40K `.drv` files.
Performance before the change:
$ time nix store gc --dry-run
real 4m22,148s
Performance after the change:
$ time nix store gc --dry-run
real 0m14,178s
945 lines
32 KiB
C++
945 lines
32 KiB
C++
#include "derivations.hh"
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#include "globals.hh"
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#include "local-store.hh"
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#include "local-fs-store.hh"
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#include "finally.hh"
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#include <functional>
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#include <queue>
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#include <algorithm>
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#include <regex>
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#include <random>
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#include <climits>
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#include <errno.h>
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#include <fcntl.h>
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#include <poll.h>
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#include <sys/socket.h>
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#include <sys/stat.h>
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#include <sys/statvfs.h>
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#include <sys/types.h>
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#include <sys/un.h>
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#include <unistd.h>
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namespace nix {
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static std::string gcSocketPath = "/gc-socket/socket";
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static std::string gcRootsDir = "gcroots";
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static void makeSymlink(const Path & link, const Path & target)
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{
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/* Create directories up to `gcRoot'. */
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createDirs(dirOf(link));
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/* Create the new symlink. */
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Path tempLink = (format("%1%.tmp-%2%-%3%")
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% link % getpid() % random()).str();
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createSymlink(target, tempLink);
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/* Atomically replace the old one. */
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if (rename(tempLink.c_str(), link.c_str()) == -1)
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throw SysError("cannot rename '%1%' to '%2%'",
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tempLink , link);
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}
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void LocalStore::addIndirectRoot(const Path & path)
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{
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std::string hash = hashString(htSHA1, path).to_string(Base32, false);
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Path realRoot = canonPath(fmt("%1%/%2%/auto/%3%", stateDir, gcRootsDir, hash));
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makeSymlink(realRoot, path);
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}
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Path LocalFSStore::addPermRoot(const StorePath & storePath, const Path & _gcRoot)
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{
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Path gcRoot(canonPath(_gcRoot));
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if (isInStore(gcRoot))
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throw Error(
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"creating a garbage collector root (%1%) in the Nix store is forbidden "
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"(are you running nix-build inside the store?)", gcRoot);
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/* Register this root with the garbage collector, if it's
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running. This should be superfluous since the caller should
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have registered this root yet, but let's be on the safe
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side. */
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addTempRoot(storePath);
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/* Don't clobber the link if it already exists and doesn't
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point to the Nix store. */
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if (pathExists(gcRoot) && (!isLink(gcRoot) || !isInStore(readLink(gcRoot))))
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throw Error("cannot create symlink '%1%'; already exists", gcRoot);
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makeSymlink(gcRoot, printStorePath(storePath));
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addIndirectRoot(gcRoot);
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return gcRoot;
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}
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void LocalStore::addTempRoot(const StorePath & path)
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{
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auto state(_state.lock());
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/* Create the temporary roots file for this process. */
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if (!state->fdTempRoots) {
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while (1) {
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if (pathExists(fnTempRoots))
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/* It *must* be stale, since there can be no two
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processes with the same pid. */
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unlink(fnTempRoots.c_str());
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state->fdTempRoots = openLockFile(fnTempRoots, true);
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debug("acquiring write lock on '%s'", fnTempRoots);
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lockFile(state->fdTempRoots.get(), ltWrite, true);
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/* Check whether the garbage collector didn't get in our
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way. */
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struct stat st;
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if (fstat(state->fdTempRoots.get(), &st) == -1)
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throw SysError("statting '%1%'", fnTempRoots);
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if (st.st_size == 0) break;
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/* The garbage collector deleted this file before we could
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get a lock. (It won't delete the file after we get a
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lock.) Try again. */
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}
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}
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if (!state->fdGCLock)
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state->fdGCLock = openGCLock();
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restart:
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FdLock gcLock(state->fdGCLock.get(), ltRead, false, "");
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if (!gcLock.acquired) {
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/* We couldn't get a shared global GC lock, so the garbage
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collector is running. So we have to connect to the garbage
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collector and inform it about our root. */
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if (!state->fdRootsSocket) {
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auto socketPath = stateDir.get() + gcSocketPath;
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debug("connecting to '%s'", socketPath);
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state->fdRootsSocket = createUnixDomainSocket();
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try {
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nix::connect(state->fdRootsSocket.get(), socketPath);
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} catch (SysError & e) {
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/* The garbage collector may have exited, so we need to
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restart. */
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if (e.errNo == ECONNREFUSED) {
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debug("GC socket connection refused");
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state->fdRootsSocket.close();
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goto restart;
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}
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}
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}
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try {
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debug("sending GC root '%s'", printStorePath(path));
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writeFull(state->fdRootsSocket.get(), printStorePath(path) + "\n", false);
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char c;
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readFull(state->fdRootsSocket.get(), &c, 1);
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assert(c == '1');
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debug("got ack for GC root '%s'", printStorePath(path));
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} catch (SysError & e) {
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/* The garbage collector may have exited, so we need to
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restart. */
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if (e.errNo == EPIPE) {
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debug("GC socket disconnected");
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state->fdRootsSocket.close();
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goto restart;
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}
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} catch (EndOfFile & e) {
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debug("GC socket disconnected");
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state->fdRootsSocket.close();
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goto restart;
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}
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}
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/* Append the store path to the temporary roots file. */
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auto s = printStorePath(path) + '\0';
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writeFull(state->fdTempRoots.get(), s);
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}
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static std::string censored = "{censored}";
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void LocalStore::findTempRoots(Roots & tempRoots, bool censor)
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{
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/* Read the `temproots' directory for per-process temporary root
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files. */
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for (auto & i : readDirectory(tempRootsDir)) {
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if (i.name[0] == '.') {
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// Ignore hidden files. Some package managers (notably portage) create
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// those to keep the directory alive.
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continue;
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}
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Path path = tempRootsDir + "/" + i.name;
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pid_t pid = std::stoi(i.name);
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debug(format("reading temporary root file '%1%'") % path);
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AutoCloseFD fd(open(path.c_str(), O_CLOEXEC | O_RDWR, 0666));
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if (!fd) {
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/* It's okay if the file has disappeared. */
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if (errno == ENOENT) continue;
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throw SysError("opening temporary roots file '%1%'", path);
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}
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/* Try to acquire a write lock without blocking. This can
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only succeed if the owning process has died. In that case
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we don't care about its temporary roots. */
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if (lockFile(fd.get(), ltWrite, false)) {
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printInfo("removing stale temporary roots file '%1%'", path);
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unlink(path.c_str());
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writeFull(fd.get(), "d");
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continue;
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}
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/* Read the entire file. */
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auto contents = readFile(fd.get());
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/* Extract the roots. */
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std::string::size_type pos = 0, end;
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while ((end = contents.find((char) 0, pos)) != std::string::npos) {
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Path root(contents, pos, end - pos);
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debug("got temporary root '%s'", root);
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tempRoots[parseStorePath(root)].emplace(censor ? censored : fmt("{temp:%d}", pid));
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pos = end + 1;
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}
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}
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}
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void LocalStore::findRoots(const Path & path, unsigned char type, Roots & roots)
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{
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auto foundRoot = [&](const Path & path, const Path & target) {
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try {
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auto storePath = toStorePath(target).first;
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if (isValidPath(storePath))
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roots[std::move(storePath)].emplace(path);
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else
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printInfo("skipping invalid root from '%1%' to '%2%'", path, target);
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} catch (BadStorePath &) { }
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};
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try {
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if (type == DT_UNKNOWN)
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type = getFileType(path);
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if (type == DT_DIR) {
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for (auto & i : readDirectory(path))
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findRoots(path + "/" + i.name, i.type, roots);
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}
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else if (type == DT_LNK) {
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Path target = readLink(path);
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if (isInStore(target))
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foundRoot(path, target);
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/* Handle indirect roots. */
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else {
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target = absPath(target, dirOf(path));
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if (!pathExists(target)) {
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if (isInDir(path, stateDir + "/" + gcRootsDir + "/auto")) {
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printInfo(format("removing stale link from '%1%' to '%2%'") % path % target);
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unlink(path.c_str());
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}
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} else {
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struct stat st2 = lstat(target);
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if (!S_ISLNK(st2.st_mode)) return;
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Path target2 = readLink(target);
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if (isInStore(target2)) foundRoot(target, target2);
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}
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}
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}
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else if (type == DT_REG) {
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auto storePath = maybeParseStorePath(storeDir + "/" + std::string(baseNameOf(path)));
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if (storePath && isValidPath(*storePath))
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roots[std::move(*storePath)].emplace(path);
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}
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}
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catch (SysError & e) {
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/* We only ignore permanent failures. */
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if (e.errNo == EACCES || e.errNo == ENOENT || e.errNo == ENOTDIR)
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printInfo("cannot read potential root '%1%'", path);
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else
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throw;
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}
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}
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void LocalStore::findRootsNoTemp(Roots & roots, bool censor)
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{
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/* Process direct roots in {gcroots,profiles}. */
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findRoots(stateDir + "/" + gcRootsDir, DT_UNKNOWN, roots);
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findRoots(stateDir + "/profiles", DT_UNKNOWN, roots);
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/* Add additional roots returned by different platforms-specific
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heuristics. This is typically used to add running programs to
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the set of roots (to prevent them from being garbage collected). */
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findRuntimeRoots(roots, censor);
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}
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Roots LocalStore::findRoots(bool censor)
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{
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Roots roots;
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findRootsNoTemp(roots, censor);
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findTempRoots(roots, censor);
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return roots;
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}
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typedef std::unordered_map<Path, std::unordered_set<std::string>> UncheckedRoots;
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static void readProcLink(const std::string & file, UncheckedRoots & roots)
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{
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/* 64 is the starting buffer size gnu readlink uses... */
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auto bufsiz = ssize_t{64};
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try_again:
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char buf[bufsiz];
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auto res = readlink(file.c_str(), buf, bufsiz);
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if (res == -1) {
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if (errno == ENOENT || errno == EACCES || errno == ESRCH)
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return;
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throw SysError("reading symlink");
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}
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if (res == bufsiz) {
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if (SSIZE_MAX / 2 < bufsiz)
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throw Error("stupidly long symlink");
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bufsiz *= 2;
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goto try_again;
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}
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if (res > 0 && buf[0] == '/')
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roots[std::string(static_cast<char *>(buf), res)]
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.emplace(file);
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}
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static std::string quoteRegexChars(const std::string & raw)
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{
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static auto specialRegex = std::regex(R"([.^$\\*+?()\[\]{}|])");
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return std::regex_replace(raw, specialRegex, R"(\$&)");
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}
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#if __linux__
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static void readFileRoots(const char * path, UncheckedRoots & roots)
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{
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try {
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roots[readFile(path)].emplace(path);
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} catch (SysError & e) {
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if (e.errNo != ENOENT && e.errNo != EACCES)
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throw;
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}
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}
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#endif
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void LocalStore::findRuntimeRoots(Roots & roots, bool censor)
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{
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UncheckedRoots unchecked;
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auto procDir = AutoCloseDir{opendir("/proc")};
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if (procDir) {
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struct dirent * ent;
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auto digitsRegex = std::regex(R"(^\d+$)");
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auto mapRegex = std::regex(R"(^\s*\S+\s+\S+\s+\S+\s+\S+\s+\S+\s+(/\S+)\s*$)");
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auto storePathRegex = std::regex(quoteRegexChars(storeDir) + R"(/[0-9a-z]+[0-9a-zA-Z\+\-\._\?=]*)");
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while (errno = 0, ent = readdir(procDir.get())) {
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checkInterrupt();
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if (std::regex_match(ent->d_name, digitsRegex)) {
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readProcLink(fmt("/proc/%s/exe" ,ent->d_name), unchecked);
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readProcLink(fmt("/proc/%s/cwd", ent->d_name), unchecked);
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auto fdStr = fmt("/proc/%s/fd", ent->d_name);
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auto fdDir = AutoCloseDir(opendir(fdStr.c_str()));
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if (!fdDir) {
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if (errno == ENOENT || errno == EACCES)
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continue;
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throw SysError("opening %1%", fdStr);
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}
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struct dirent * fd_ent;
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while (errno = 0, fd_ent = readdir(fdDir.get())) {
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if (fd_ent->d_name[0] != '.')
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readProcLink(fmt("%s/%s", fdStr, fd_ent->d_name), unchecked);
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}
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if (errno) {
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if (errno == ESRCH)
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continue;
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throw SysError("iterating /proc/%1%/fd", ent->d_name);
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}
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fdDir.reset();
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try {
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auto mapFile = fmt("/proc/%s/maps", ent->d_name);
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auto mapLines = tokenizeString<std::vector<std::string>>(readFile(mapFile), "\n");
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for (const auto & line : mapLines) {
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auto match = std::smatch{};
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if (std::regex_match(line, match, mapRegex))
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unchecked[match[1]].emplace(mapFile);
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}
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auto envFile = fmt("/proc/%s/environ", ent->d_name);
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auto envString = readFile(envFile);
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auto env_end = std::sregex_iterator{};
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for (auto i = std::sregex_iterator{envString.begin(), envString.end(), storePathRegex}; i != env_end; ++i)
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unchecked[i->str()].emplace(envFile);
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} catch (SysError & e) {
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if (errno == ENOENT || errno == EACCES || errno == ESRCH)
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continue;
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throw;
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}
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}
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}
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if (errno)
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throw SysError("iterating /proc");
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}
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#if !defined(__linux__)
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// lsof is really slow on OS X. This actually causes the gc-concurrent.sh test to fail.
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// See: https://github.com/NixOS/nix/issues/3011
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// Because of this we disable lsof when running the tests.
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if (getEnv("_NIX_TEST_NO_LSOF") != "1") {
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try {
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std::regex lsofRegex(R"(^n(/.*)$)");
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auto lsofLines =
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tokenizeString<std::vector<std::string>>(runProgram(LSOF, true, { "-n", "-w", "-F", "n" }), "\n");
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for (const auto & line : lsofLines) {
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std::smatch match;
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if (std::regex_match(line, match, lsofRegex))
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unchecked[match[1]].emplace("{lsof}");
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}
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} catch (ExecError & e) {
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/* lsof not installed, lsof failed */
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}
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}
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#endif
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#if __linux__
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readFileRoots("/proc/sys/kernel/modprobe", unchecked);
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readFileRoots("/proc/sys/kernel/fbsplash", unchecked);
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readFileRoots("/proc/sys/kernel/poweroff_cmd", unchecked);
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#endif
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for (auto & [target, links] : unchecked) {
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if (!isInStore(target)) continue;
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try {
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auto path = toStorePath(target).first;
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if (!isValidPath(path)) continue;
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debug("got additional root '%1%'", printStorePath(path));
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if (censor)
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roots[path].insert(censored);
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else
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roots[path].insert(links.begin(), links.end());
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} catch (BadStorePath &) { }
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}
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}
|
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|
|
|
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struct GCLimitReached { };
|
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|
|
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void LocalStore::collectGarbage(const GCOptions & options, GCResults & results)
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{
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bool shouldDelete = options.action == GCOptions::gcDeleteDead || options.action == GCOptions::gcDeleteSpecific;
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bool gcKeepOutputs = settings.gcKeepOutputs;
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bool gcKeepDerivations = settings.gcKeepDerivations;
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StorePathSet roots, dead, alive;
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struct Shared
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{
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// The temp roots only store the hash part to make it easier to
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// ignore suffixes like '.lock', '.chroot' and '.check'.
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std::unordered_set<std::string> tempRoots;
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// Hash part of the store path currently being deleted, if
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// any.
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std::optional<std::string> pending;
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};
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Sync<Shared> _shared;
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std::condition_variable wakeup;
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|
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/* Using `--ignore-liveness' with `--delete' can have unintended
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consequences if `keep-outputs' or `keep-derivations' are true
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(the garbage collector will recurse into deleting the outputs
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or derivers, respectively). So disable them. */
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if (options.action == GCOptions::gcDeleteSpecific && options.ignoreLiveness) {
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gcKeepOutputs = false;
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gcKeepDerivations = false;
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}
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|
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if (shouldDelete)
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deletePath(reservedPath);
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|
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/* Acquire the global GC root. Note: we don't use fdGCLock
|
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here because then in auto-gc mode, another thread could
|
|
downgrade our exclusive lock. */
|
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auto fdGCLock = openGCLock();
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FdLock gcLock(fdGCLock.get(), ltWrite, true, "waiting for the big garbage collector lock...");
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|
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/* Start the server for receiving new roots. */
|
|
auto socketPath = stateDir.get() + gcSocketPath;
|
|
createDirs(dirOf(socketPath));
|
|
auto fdServer = createUnixDomainSocket(socketPath, 0666);
|
|
|
|
if (fcntl(fdServer.get(), F_SETFL, fcntl(fdServer.get(), F_GETFL) | O_NONBLOCK) == -1)
|
|
throw SysError("making socket '%1%' non-blocking", socketPath);
|
|
|
|
Pipe shutdownPipe;
|
|
shutdownPipe.create();
|
|
|
|
std::thread serverThread([&]() {
|
|
Sync<std::map<int, std::thread>> connections;
|
|
|
|
Finally cleanup([&]() {
|
|
debug("GC roots server shutting down");
|
|
while (true) {
|
|
auto item = remove_begin(*connections.lock());
|
|
if (!item) break;
|
|
auto & [fd, thread] = *item;
|
|
shutdown(fd, SHUT_RDWR);
|
|
thread.join();
|
|
}
|
|
});
|
|
|
|
while (true) {
|
|
std::vector<struct pollfd> fds;
|
|
fds.push_back({.fd = shutdownPipe.readSide.get(), .events = POLLIN});
|
|
fds.push_back({.fd = fdServer.get(), .events = POLLIN});
|
|
auto count = poll(fds.data(), fds.size(), -1);
|
|
assert(count != -1);
|
|
|
|
if (fds[0].revents)
|
|
/* Parent is asking us to quit. */
|
|
break;
|
|
|
|
if (fds[1].revents) {
|
|
/* Accept a new connection. */
|
|
assert(fds[1].revents & POLLIN);
|
|
AutoCloseFD fdClient = accept(fdServer.get(), nullptr, nullptr);
|
|
if (!fdClient) continue;
|
|
|
|
debug("GC roots server accepted new client");
|
|
|
|
/* Process the connection in a separate thread. */
|
|
auto fdClient_ = fdClient.get();
|
|
std::thread clientThread([&, fdClient = std::move(fdClient)]() {
|
|
Finally cleanup([&]() {
|
|
auto conn(connections.lock());
|
|
auto i = conn->find(fdClient.get());
|
|
if (i != conn->end()) {
|
|
i->second.detach();
|
|
conn->erase(i);
|
|
}
|
|
});
|
|
|
|
/* On macOS, accepted sockets inherit the
|
|
non-blocking flag from the server socket, so
|
|
explicitly make it blocking. */
|
|
if (fcntl(fdServer.get(), F_SETFL, fcntl(fdServer.get(), F_GETFL) & ~O_NONBLOCK) == -1)
|
|
abort();
|
|
|
|
while (true) {
|
|
try {
|
|
auto path = readLine(fdClient.get());
|
|
auto storePath = maybeParseStorePath(path);
|
|
if (storePath) {
|
|
debug("got new GC root '%s'", path);
|
|
auto hashPart = std::string(storePath->hashPart());
|
|
auto shared(_shared.lock());
|
|
shared->tempRoots.insert(hashPart);
|
|
/* If this path is currently being
|
|
deleted, then we have to wait until
|
|
deletion is finished to ensure that
|
|
the client doesn't start
|
|
re-creating it before we're
|
|
done. FIXME: ideally we would use a
|
|
FD for this so we don't block the
|
|
poll loop. */
|
|
while (shared->pending == hashPart) {
|
|
debug("synchronising with deletion of path '%s'", path);
|
|
shared.wait(wakeup);
|
|
}
|
|
} else
|
|
printError("received garbage instead of a root from client");
|
|
writeFull(fdClient.get(), "1", false);
|
|
} catch (Error & e) {
|
|
debug("reading GC root from client: %s", e.msg());
|
|
break;
|
|
}
|
|
}
|
|
});
|
|
|
|
connections.lock()->insert({fdClient_, std::move(clientThread)});
|
|
}
|
|
}
|
|
});
|
|
|
|
Finally stopServer([&]() {
|
|
writeFull(shutdownPipe.writeSide.get(), "x", false);
|
|
wakeup.notify_all();
|
|
if (serverThread.joinable()) serverThread.join();
|
|
});
|
|
|
|
/* Find the roots. Since we've grabbed the GC lock, the set of
|
|
permanent roots cannot increase now. */
|
|
printInfo("finding garbage collector roots...");
|
|
Roots rootMap;
|
|
if (!options.ignoreLiveness)
|
|
findRootsNoTemp(rootMap, true);
|
|
|
|
for (auto & i : rootMap) roots.insert(i.first);
|
|
|
|
/* Read the temporary roots created before we acquired the global
|
|
GC root. Any new roots will be sent to our socket. */
|
|
Roots tempRoots;
|
|
findTempRoots(tempRoots, true);
|
|
for (auto & root : tempRoots) {
|
|
_shared.lock()->tempRoots.insert(std::string(root.first.hashPart()));
|
|
roots.insert(root.first);
|
|
}
|
|
|
|
/* Helper function that deletes a path from the store and throws
|
|
GCLimitReached if we've deleted enough garbage. */
|
|
auto deleteFromStore = [&](std::string_view baseName)
|
|
{
|
|
Path path = storeDir + "/" + std::string(baseName);
|
|
Path realPath = realStoreDir + "/" + std::string(baseName);
|
|
|
|
printInfo("deleting '%1%'", path);
|
|
|
|
results.paths.insert(path);
|
|
|
|
uint64_t bytesFreed;
|
|
deletePath(realPath, bytesFreed);
|
|
results.bytesFreed += bytesFreed;
|
|
|
|
if (results.bytesFreed > options.maxFreed) {
|
|
printInfo("deleted more than %d bytes; stopping", options.maxFreed);
|
|
throw GCLimitReached();
|
|
}
|
|
};
|
|
|
|
std::map<StorePath, StorePathSet> referrersCache;
|
|
|
|
/* Helper function that visits all paths reachable from `start`
|
|
via the referrers edges and optionally derivers and derivation
|
|
output edges. If none of those paths are roots, then all
|
|
visited paths are garbage and are deleted. */
|
|
auto deleteReferrersClosure = [&](const StorePath & start) {
|
|
StorePathSet visited;
|
|
std::queue<StorePath> todo;
|
|
|
|
/* Wake up any GC client waiting for deletion of the paths in
|
|
'visited' to finish. */
|
|
Finally releasePending([&]() {
|
|
auto shared(_shared.lock());
|
|
shared->pending.reset();
|
|
wakeup.notify_all();
|
|
});
|
|
|
|
auto enqueue = [&](const StorePath & path) {
|
|
if (visited.insert(path).second)
|
|
todo.push(path);
|
|
};
|
|
|
|
enqueue(start);
|
|
|
|
while (auto path = pop(todo)) {
|
|
checkInterrupt();
|
|
|
|
/* Bail out if we've previously discovered that this path
|
|
is alive. */
|
|
if (alive.count(*path)) {
|
|
alive.insert(start);
|
|
return;
|
|
}
|
|
|
|
/* If we've previously deleted this path, we don't have to
|
|
handle it again. */
|
|
if (dead.count(*path)) continue;
|
|
|
|
auto markAlive = [&]()
|
|
{
|
|
alive.insert(*path);
|
|
alive.insert(start);
|
|
try {
|
|
StorePathSet closure;
|
|
computeFSClosure(*path, closure,
|
|
/* flipDirection */ false, gcKeepOutputs, gcKeepDerivations);
|
|
for (auto & p : closure)
|
|
alive.insert(p);
|
|
} catch (InvalidPath &) { }
|
|
};
|
|
|
|
/* If this is a root, bail out. */
|
|
if (roots.count(*path)) {
|
|
debug("cannot delete '%s' because it's a root", printStorePath(*path));
|
|
return markAlive();
|
|
}
|
|
|
|
if (options.action == GCOptions::gcDeleteSpecific
|
|
&& !options.pathsToDelete.count(*path))
|
|
return;
|
|
|
|
{
|
|
auto hashPart = std::string(path->hashPart());
|
|
auto shared(_shared.lock());
|
|
if (shared->tempRoots.count(hashPart)) {
|
|
debug("cannot delete '%s' because it's a temporary root", printStorePath(*path));
|
|
return markAlive();
|
|
}
|
|
shared->pending = hashPart;
|
|
}
|
|
|
|
if (isValidPath(*path)) {
|
|
|
|
/* Visit the referrers of this path. */
|
|
auto i = referrersCache.find(*path);
|
|
if (i == referrersCache.end()) {
|
|
StorePathSet referrers;
|
|
queryReferrers(*path, referrers);
|
|
referrersCache.emplace(*path, std::move(referrers));
|
|
i = referrersCache.find(*path);
|
|
}
|
|
for (auto & p : i->second)
|
|
enqueue(p);
|
|
|
|
/* If keep-derivations is set and this is a
|
|
derivation, then visit the derivation outputs. */
|
|
if (gcKeepDerivations && path->isDerivation()) {
|
|
for (auto & [name, maybeOutPath] : queryPartialDerivationOutputMap(*path))
|
|
if (maybeOutPath &&
|
|
isValidPath(*maybeOutPath) &&
|
|
queryPathInfo(*maybeOutPath)->deriver == *path)
|
|
enqueue(*maybeOutPath);
|
|
}
|
|
|
|
/* If keep-outputs is set, then visit the derivers. */
|
|
if (gcKeepOutputs) {
|
|
auto derivers = queryValidDerivers(*path);
|
|
for (auto & i : derivers)
|
|
enqueue(i);
|
|
}
|
|
}
|
|
}
|
|
|
|
for (auto & path : topoSortPaths(visited)) {
|
|
if (!dead.insert(path).second) continue;
|
|
if (shouldDelete) {
|
|
invalidatePathChecked(path);
|
|
deleteFromStore(path.to_string());
|
|
referrersCache.erase(path);
|
|
}
|
|
}
|
|
};
|
|
|
|
/* Synchronisation point for testing, see tests/gc-concurrent.sh. */
|
|
if (auto p = getEnv("_NIX_TEST_GC_SYNC"))
|
|
readFile(*p);
|
|
|
|
/* Either delete all garbage paths, or just the specified
|
|
paths (for gcDeleteSpecific). */
|
|
if (options.action == GCOptions::gcDeleteSpecific) {
|
|
|
|
for (auto & i : options.pathsToDelete) {
|
|
deleteReferrersClosure(i);
|
|
if (!dead.count(i))
|
|
throw Error(
|
|
"Cannot delete path '%1%' since it is still alive. "
|
|
"To find out why, use: "
|
|
"nix-store --query --roots",
|
|
printStorePath(i));
|
|
}
|
|
|
|
} else if (options.maxFreed > 0) {
|
|
|
|
if (shouldDelete)
|
|
printInfo("deleting garbage...");
|
|
else
|
|
printInfo("determining live/dead paths...");
|
|
|
|
try {
|
|
AutoCloseDir dir(opendir(realStoreDir.get().c_str()));
|
|
if (!dir) throw SysError("opening directory '%1%'", realStoreDir);
|
|
|
|
/* Read the store and delete all paths that are invalid or
|
|
unreachable. We don't use readDirectory() here so that
|
|
GCing can start faster. */
|
|
auto linksName = baseNameOf(linksDir);
|
|
Paths entries;
|
|
struct dirent * dirent;
|
|
while (errno = 0, dirent = readdir(dir.get())) {
|
|
checkInterrupt();
|
|
std::string name = dirent->d_name;
|
|
if (name == "." || name == ".." || name == linksName) continue;
|
|
|
|
if (auto storePath = maybeParseStorePath(storeDir + "/" + name))
|
|
deleteReferrersClosure(*storePath);
|
|
else
|
|
deleteFromStore(name);
|
|
|
|
}
|
|
} catch (GCLimitReached & e) {
|
|
}
|
|
}
|
|
|
|
if (options.action == GCOptions::gcReturnLive) {
|
|
for (auto & i : alive)
|
|
results.paths.insert(printStorePath(i));
|
|
return;
|
|
}
|
|
|
|
if (options.action == GCOptions::gcReturnDead) {
|
|
for (auto & i : dead)
|
|
results.paths.insert(printStorePath(i));
|
|
return;
|
|
}
|
|
|
|
/* 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. */
|
|
if (options.action == GCOptions::gcDeleteDead || options.action == GCOptions::gcDeleteSpecific) {
|
|
printInfo("deleting unused links...");
|
|
|
|
AutoCloseDir dir(opendir(linksDir.c_str()));
|
|
if (!dir) throw SysError("opening directory '%1%'", linksDir);
|
|
|
|
int64_t actualSize = 0, 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;
|
|
|
|
auto st = lstat(path);
|
|
|
|
if (st.st_nlink != 1) {
|
|
actualSize += st.st_size;
|
|
unsharedSize += (st.st_nlink - 1) * st.st_size;
|
|
continue;
|
|
}
|
|
|
|
printMsg(lvlTalkative, format("deleting unused link '%1%'") % path);
|
|
|
|
if (unlink(path.c_str()) == -1)
|
|
throw SysError("deleting '%1%'", path);
|
|
|
|
/* Do not accound for deleted file here. Rely on deletePath()
|
|
accounting. */
|
|
}
|
|
|
|
struct stat st;
|
|
if (stat(linksDir.c_str(), &st) == -1)
|
|
throw SysError("statting '%1%'", linksDir);
|
|
int64_t overhead = st.st_blocks * 512ULL;
|
|
|
|
printInfo("note: currently hard linking saves %.2f MiB",
|
|
((unsharedSize - actualSize - overhead) / (1024.0 * 1024.0)));
|
|
}
|
|
|
|
/* 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");
|
|
|
|
auto getAvail = [this]() -> uint64_t {
|
|
if (fakeFreeSpaceFile)
|
|
return std::stoll(readFile(*fakeFreeSpaceFile));
|
|
|
|
struct statvfs st;
|
|
if (statvfs(realStoreDir.get().c_str(), &st))
|
|
throw SysError("getting filesystem info about '%s'", realStoreDir);
|
|
|
|
return (uint64_t) st.f_bavail * st.f_frsize;
|
|
};
|
|
|
|
std::shared_future<void> future;
|
|
|
|
{
|
|
auto state(_state.lock());
|
|
|
|
if (state->gcRunning) {
|
|
future = state->gcFuture;
|
|
debug("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;
|
|
|
|
printInfo("running auto-GC to free %d bytes", options.maxFreed);
|
|
|
|
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();
|
|
}
|
|
|
|
|
|
}
|