replace more std::unordered_* types by faster boost hash maps

src/libstore/derivations.cc

@@ -11,6 +11,7 @@
 #include "nix/util/json-utils.hh"
 
 #include <boost/container/small_vector.hpp>
+#include <boost/unordered/concurrent_flat_map.hpp>
 #include <nlohmann/json.hpp>
 
 namespace nix {
@@ -834,7 +835,7 @@ DerivationType BasicDerivation::type() const
     throw Error("can't mix derivation output types");
 }
 
-Sync<DrvHashes> drvHashes;
+DrvHashes drvHashes;
 
 /* pathDerivationModulo and hashDerivationModulo are mutually recursive
  */
@@ -844,16 +845,13 @@ Sync<DrvHashes> drvHashes;
  */
 static const DrvHash pathDerivationModulo(Store & store, const StorePath & drvPath)
 {
-    {
-        auto hashes = drvHashes.lock();
-        auto h = hashes->find(drvPath);
-        if (h != hashes->end()) {
-            return h->second;
-        }
+    std::optional<DrvHash> hash;
+    if (drvHashes.cvisit(drvPath, [&hash](const auto & kv) { hash.emplace(kv.second); })) {
+        return *hash;
     }
     auto h = hashDerivationModulo(store, store.readInvalidDerivation(drvPath), false);
     // Cache it
-    drvHashes.lock()->insert_or_assign(drvPath, h);
+    drvHashes.insert_or_assign(drvPath, h);
     return h;
 }
 

src/libstore/gc.cc

@@ -1,6 +1,7 @@
 #include "nix/store/derivations.hh"
 #include "nix/store/globals.hh"
 #include "nix/store/local-store.hh"
+#include "nix/store/path.hh"
 #include "nix/util/finally.hh"
 #include "nix/util/unix-domain-socket.hh"
 #include "nix/util/signals.hh"
@@ -13,14 +14,10 @@
 #  include "nix/util/processes.hh"
 #endif
 
+#include <boost/unordered/unordered_flat_map.hpp>
+#include <boost/unordered/unordered_flat_set.hpp>
 #include <boost/regex.hpp>
-
-#include <functional>
 #include <queue>
-#include <algorithm>
-#include <random>
-
-#include <climits>
 #include <errno.h>
 #include <fcntl.h>
 #include <sys/stat.h>
@@ -314,7 +311,7 @@ Roots LocalStore::findRoots(bool censor)
 /**
  * Key is a mere string because cannot has path with macOS's libc++
  */
-typedef std::unordered_map<std::string, std::unordered_set<std::string>> UncheckedRoots;
+typedef boost::unordered_flat_map<std::string, boost::unordered_flat_set<std::string>> UncheckedRoots;
 
 static void readProcLink(const std::filesystem::path & file, UncheckedRoots & roots)
 {
@@ -463,13 +460,13 @@ void LocalStore::collectGarbage(const GCOptions & options, GCResults & results)
     bool gcKeepOutputs = settings.gcKeepOutputs;
     bool gcKeepDerivations = settings.gcKeepDerivations;
 
-    std::unordered_set<StorePath> roots, dead, alive;
+    boost::unordered_flat_set<StorePath, std::hash<StorePath>> roots, dead, alive;
 
     struct Shared
     {
         // The temp roots only store the hash part to make it easier to
         // ignore suffixes like '.lock', '.chroot' and '.check'.
-        std::unordered_set<std::string> tempRoots;
+        boost::unordered_flat_set<std::string> tempRoots;
 
         // Hash part of the store path currently being deleted, if
         // any.
@@ -672,7 +669,7 @@ void LocalStore::collectGarbage(const GCOptions & options, GCResults & results)
         }
     };
 
-    std::unordered_map<StorePath, StorePathSet> referrersCache;
+    boost::unordered_flat_map<StorePath, StorePathSet, std::hash<StorePath>> referrersCache;
 
     /* Helper function that visits all paths reachable from `start`
        via the referrers edges and optionally derivers and derivation

src/libstore/include/nix/store/derivations.hh

@@ -11,7 +11,7 @@
 #include "nix/util/sync.hh"
 #include "nix/util/variant-wrapper.hh"
 
-#include <map>
+#include <boost/unordered/concurrent_flat_map_fwd.hpp>
 #include <variant>
 
 namespace nix {
@@ -507,13 +507,23 @@ DrvHash hashDerivationModulo(Store & store, const Derivation & drv, bool maskOut
  */
 std::map<std::string, Hash> staticOutputHashes(Store & store, const Derivation & drv);
 
+struct DrvHashFct
+{
+    using is_avalanching = std::true_type;
+
+    std::size_t operator()(const StorePath & path) const noexcept
+    {
+        return std::hash<std::string_view>{}(path.to_string());
+    }
+};
+
 /**
  * Memoisation of hashDerivationModulo().
  */
-typedef std::map<StorePath, DrvHash> DrvHashes;
+typedef boost::concurrent_flat_map<StorePath, DrvHash, DrvHashFct> DrvHashes;
 
 // FIXME: global, though at least thread-safe.
-extern Sync<DrvHashes> drvHashes;
+extern DrvHashes drvHashes;
 
 struct Source;
 struct Sink;

src/libstore/include/nix/store/gc-store.hh

@@ -1,13 +1,13 @@
 #pragma once
 ///@file
 
-#include <unordered_set>
-
 #include "nix/store/store-api.hh"
+#include <boost/unordered/unordered_flat_map.hpp>
+#include <boost/unordered/unordered_flat_set.hpp>
 
 namespace nix {
 
-typedef std::unordered_map<StorePath, std::unordered_set<std::string>> Roots;
+typedef boost::unordered_flat_map<StorePath, boost::unordered_flat_set<std::string>, std::hash<StorePath>> Roots;
 
 struct GCOptions
 {

src/libstore/include/nix/store/local-store.hh

@@ -11,7 +11,7 @@
 #include <chrono>
 #include <future>
 #include <string>
-#include <unordered_set>
+#include <boost/unordered/unordered_flat_set.hpp>
 
 namespace nix {
 
@@ -442,7 +442,7 @@ private:
 
     std::pair<std::filesystem::path, AutoCloseFD> createTempDirInStore();
 
-    typedef std::unordered_set<ino_t> InodeHash;
+    typedef boost::unordered_flat_set<ino_t> InodeHash;
 
     InodeHash loadInodeHash();
     Strings readDirectoryIgnoringInodes(const Path & path, const InodeHash & inodeHash);

src/libstore/misc.cc

@@ -1,5 +1,3 @@
-#include <unordered_set>
-
 #include "nix/store/derivations.hh"
 #include "nix/store/parsed-derivations.hh"
 #include "nix/store/derivation-options.hh"
@@ -13,6 +11,8 @@
 #include "nix/store/filetransfer.hh"
 #include "nix/util/strings.hh"
 
+#include <boost/unordered/unordered_flat_set.hpp>
+
 namespace nix {
 
 void Store::computeFSClosure(
@@ -106,7 +106,7 @@ MissingPaths Store::queryMissing(const std::vector<DerivedPath> & targets)
 
     struct State
     {
-        std::unordered_set<std::string> done;
+        boost::unordered_flat_set<std::string> done;
         MissingPaths res;
     };