Merge pull request #3895 from obsidiansystems/templated-daemon-protocol

More templated STL support for the daemon protocol

src/libstore/build.cc

@@ -2070,7 +2070,7 @@ HookReply DerivationGoal::tryBuildHook()
 
     /* Tell the hook all the inputs that have to be copied to the
        remote system. */
-    writeStorePaths(worker.store, hook->sink, inputPaths);
+    worker_proto::write(worker.store, hook->sink, inputPaths);
 
     /* Tell the hooks the missing outputs that have to be copied back
        from the remote system. */
@@ -2081,7 +2081,7 @@ HookReply DerivationGoal::tryBuildHook()
             if (buildMode != bmCheck && status.known->isValid()) continue;
             missingPaths.insert(status.known->path);
         }
-        writeStorePaths(worker.store, hook->sink, missingPaths);
+        worker_proto::write(worker.store, hook->sink, missingPaths);
     }
 
     hook->sink = FdSink();

src/libstore/daemon.cc

@@ -247,7 +247,7 @@ static void writeValidPathInfo(
 {
     to << (info->deriver ? store->printStorePath(*info->deriver) : "")
        << info->narHash.to_string(Base16, false);
-    writeStorePaths(*store, to, info->references);
+    worker_proto::write(*store, to, info->references);
     to << info->registrationTime << info->narSize;
     if (GET_PROTOCOL_MINOR(clientVersion) >= 16) {
         to << info->ultimate
@@ -272,11 +272,11 @@ static void performOp(TunnelLogger * logger, ref<Store> store,
     }
 
     case wopQueryValidPaths: {
-        auto paths = readStorePaths<StorePathSet>(*store, from);
+        auto paths = worker_proto::read(*store, from, Phantom<StorePathSet> {});
         logger->startWork();
         auto res = store->queryValidPaths(paths);
         logger->stopWork();
-        writeStorePaths(*store, to, res);
+        worker_proto::write(*store, to, res);
         break;
     }
 
@@ -292,11 +292,11 @@ static void performOp(TunnelLogger * logger, ref<Store> store,
     }
 
     case wopQuerySubstitutablePaths: {
-        auto paths = readStorePaths<StorePathSet>(*store, from);
+        auto paths = worker_proto::read(*store, from, Phantom<StorePathSet> {});
         logger->startWork();
         auto res = store->querySubstitutablePaths(paths);
         logger->stopWork();
-        writeStorePaths(*store, to, res);
+        worker_proto::write(*store, to, res);
         break;
     }
 
@@ -325,7 +325,7 @@ static void performOp(TunnelLogger * logger, ref<Store> store,
             paths = store->queryValidDerivers(path);
         else paths = store->queryDerivationOutputs(path);
         logger->stopWork();
-        writeStorePaths(*store, to, paths);
+        worker_proto::write(*store, to, paths);
         break;
     }
 
@@ -369,7 +369,7 @@ static void performOp(TunnelLogger * logger, ref<Store> store,
         if (GET_PROTOCOL_MINOR(clientVersion) >= 25) {
             auto name = readString(from);
             auto camStr = readString(from);
-            auto refs = readStorePaths<StorePathSet>(*store, from);
+            auto refs = worker_proto::read(*store, from, Phantom<StorePathSet> {});
             bool repairBool;
             from >> repairBool;
             auto repair = RepairFlag{repairBool};
@@ -449,7 +449,7 @@ static void performOp(TunnelLogger * logger, ref<Store> store,
     case wopAddTextToStore: {
         string suffix = readString(from);
         string s = readString(from);
-        auto refs = readStorePaths<StorePathSet>(*store, from);
+        auto refs = worker_proto::read(*store, from, Phantom<StorePathSet> {});
         logger->startWork();
         auto path = store->addTextToStore(suffix, s, refs, NoRepair);
         logger->stopWork();
@@ -622,7 +622,7 @@ static void performOp(TunnelLogger * logger, ref<Store> store,
     case wopCollectGarbage: {
         GCOptions options;
         options.action = (GCOptions::GCAction) readInt(from);
-        options.pathsToDelete = readStorePaths<StorePathSet>(*store, from);
+        options.pathsToDelete = worker_proto::read(*store, from, Phantom<StorePathSet> {});
         from >> options.ignoreLiveness >> options.maxFreed;
         // obsolete fields
         readInt(from);
@@ -691,7 +691,7 @@ static void performOp(TunnelLogger * logger, ref<Store> store,
         else {
             to << 1
                << (i->second.deriver ? store->printStorePath(*i->second.deriver) : "");
-            writeStorePaths(*store, to, i->second.references);
+            worker_proto::write(*store, to, i->second.references);
             to << i->second.downloadSize
                << i->second.narSize;
         }
@@ -702,11 +702,11 @@ static void performOp(TunnelLogger * logger, ref<Store> store,
         SubstitutablePathInfos infos;
         StorePathCAMap pathsMap = {};
         if (GET_PROTOCOL_MINOR(clientVersion) < 22) {
-            auto paths = readStorePaths<StorePathSet>(*store, from);
+            auto paths = worker_proto::read(*store, from, Phantom<StorePathSet> {});
             for (auto & path : paths)
                 pathsMap.emplace(path, std::nullopt);
         } else
-            pathsMap = readStorePathCAMap(*store, from);
+            pathsMap = worker_proto::read(*store, from, Phantom<StorePathCAMap> {});
         logger->startWork();
         store->querySubstitutablePathInfos(pathsMap, infos);
         logger->stopWork();
@@ -714,7 +714,7 @@ static void performOp(TunnelLogger * logger, ref<Store> store,
         for (auto & i : infos) {
             to << store->printStorePath(i.first)
                << (i.second.deriver ? store->printStorePath(*i.second.deriver) : "");
-            writeStorePaths(*store, to, i.second.references);
+            worker_proto::write(*store, to, i.second.references);
             to << i.second.downloadSize << i.second.narSize;
         }
         break;
@@ -724,7 +724,7 @@ static void performOp(TunnelLogger * logger, ref<Store> store,
         logger->startWork();
         auto paths = store->queryAllValidPaths();
         logger->stopWork();
-        writeStorePaths(*store, to, paths);
+        worker_proto::write(*store, to, paths);
         break;
     }
 
@@ -796,7 +796,7 @@ static void performOp(TunnelLogger * logger, ref<Store> store,
         ValidPathInfo info { path, narHash };
         if (deriver != "")
             info.deriver = store->parseStorePath(deriver);
-        info.references = readStorePaths<StorePathSet>(*store, from);
+        info.references = worker_proto::read(*store, from, Phantom<StorePathSet> {});
         from >> info.registrationTime >> info.narSize >> info.ultimate;
         info.sigs = readStrings<StringSet>(from);
         info.ca = parseContentAddressOpt(readString(from));
@@ -849,9 +849,9 @@ static void performOp(TunnelLogger * logger, ref<Store> store,
         uint64_t downloadSize, narSize;
         store->queryMissing(targets, willBuild, willSubstitute, unknown, downloadSize, narSize);
         logger->stopWork();
-        writeStorePaths(*store, to, willBuild);
+        worker_proto::write(*store, to, willBuild);
-        writeStorePaths(*store, to, willSubstitute);
+        worker_proto::write(*store, to, willSubstitute);
-        writeStorePaths(*store, to, unknown);
+        worker_proto::write(*store, to, unknown);
         to << downloadSize << narSize;
         break;
     }

src/libstore/derivations.cc

@@ -584,7 +584,7 @@ Source & readDerivation(Source & in, const Store & store, BasicDerivation & drv,
         drv.outputs.emplace(std::move(name), std::move(output));
     }
 
-    drv.inputSrcs = readStorePaths<StorePathSet>(store, in);
+    drv.inputSrcs = worker_proto::read(store, in, Phantom<StorePathSet> {});
     in >> drv.platform >> drv.builder;
     drv.args = readStrings<Strings>(in);
 
@@ -622,7 +622,7 @@ void writeDerivation(Sink & out, const Store & store, const BasicDerivation & dr
             },
         }, i.second.output);
     }
-    writeStorePaths(store, out, drv.inputSrcs);
+    worker_proto::write(store, out, drv.inputSrcs);
     out << drv.platform << drv.builder << drv.args;
     out << drv.env.size();
     for (auto & i : drv.env)

src/libstore/export-import.cc

@@ -45,7 +45,7 @@ void Store::exportPath(const StorePath & path, Sink & sink)
     teeSink
         << exportMagic
         << printStorePath(path);
-    writeStorePaths(*this, teeSink, info->references);
+    worker_proto::write(*this, teeSink, info->references);
     teeSink
         << (info->deriver ? printStorePath(*info->deriver) : "")
         << 0;
@@ -73,7 +73,7 @@ StorePaths Store::importPaths(Source & source, CheckSigsFlag checkSigs)
 
         //Activity act(*logger, lvlInfo, format("importing path '%s'") % info.path);
 
-        auto references = readStorePaths<StorePathSet>(*this, source);
+        auto references = worker_proto::read(*this, source, Phantom<StorePathSet> {});
         auto deriver = readString(source);
         auto narHash = hashString(htSHA256, *saved.s);
 

src/libstore/legacy-ssh-store.cc

@@ -122,7 +122,7 @@ struct LegacySSHStore : public Store, public virtual LegacySSHStoreConfig
             auto deriver = readString(conn->from);
             if (deriver != "")
                 info->deriver = parseStorePath(deriver);
-            info->references = readStorePaths<StorePathSet>(*this, conn->from);
+            info->references = worker_proto::read(*this, conn->from, Phantom<StorePathSet> {});
             readLongLong(conn->from); // download size
             info->narSize = readLongLong(conn->from);
 
@@ -156,7 +156,7 @@ struct LegacySSHStore : public Store, public virtual LegacySSHStoreConfig
                 << printStorePath(info.path)
                 << (info.deriver ? printStorePath(*info.deriver) : "")
                 << info.narHash.to_string(Base16, false);
-            writeStorePaths(*this, conn->to, info.references);
+            worker_proto::write(*this, conn->to, info.references);
             conn->to
                 << info.registrationTime
                 << info.narSize
@@ -185,7 +185,7 @@ struct LegacySSHStore : public Store, public virtual LegacySSHStoreConfig
             conn->to
                 << exportMagic
                 << printStorePath(info.path);
-            writeStorePaths(*this, conn->to, info.references);
+            worker_proto::write(*this, conn->to, info.references);
             conn->to
                 << (info.deriver ? printStorePath(*info.deriver) : "")
                 << 0
@@ -301,10 +301,10 @@ public:
         conn->to
             << cmdQueryClosure
             << includeOutputs;
-        writeStorePaths(*this, conn->to, paths);
+        worker_proto::write(*this, conn->to, paths);
         conn->to.flush();
 
-        for (auto & i : readStorePaths<StorePathSet>(*this, conn->from))
+        for (auto & i : worker_proto::read(*this, conn->from, Phantom<StorePathSet> {}))
             out.insert(i);
     }
 
@@ -317,10 +317,10 @@ public:
             << cmdQueryValidPaths
             << false // lock
             << maybeSubstitute;
-        writeStorePaths(*this, conn->to, paths);
+        worker_proto::write(*this, conn->to, paths);
         conn->to.flush();
 
-        return readStorePaths<StorePathSet>(*this, conn->from);
+        return worker_proto::read(*this, conn->from, Phantom<StorePathSet> {});
     }
 
     void connect() override

src/libstore/remote-store.cc

@@ -24,47 +24,19 @@
 
 namespace nix {
 
-
-template<> StorePathSet readStorePaths(const Store & store, Source & from)
-{
-    StorePathSet paths;
-    for (auto & i : readStrings<Strings>(from))
-        paths.insert(store.parseStorePath(i));
-    return paths;
-}
-
-void writeStorePaths(const Store & store, Sink & out, const StorePathSet & paths)
-{
-    out << paths.size();
-    for (auto & i : paths)
-        out << store.printStorePath(i);
-}
-
-
-StorePathCAMap readStorePathCAMap(const Store & store, Source & from)
-{
-    StorePathCAMap paths;
-    auto count = readNum<size_t>(from);
-    while (count--) {
-        auto path = store.parseStorePath(readString(from));
-        auto ca = parseContentAddressOpt(readString(from));
-        paths.insert_or_assign(path, ca);
-    }
-    return paths;
-}
-
-void writeStorePathCAMap(const Store & store, Sink & out, const StorePathCAMap & paths)
-{
-    out << paths.size();
-    for (auto & i : paths) {
-        out << store.printStorePath(i.first);
-        out << renderContentAddress(i.second);
-    }
-}
-
-
 namespace worker_proto {
 
+std::string read(const Store & store, Source & from, Phantom<std::string> _)
+{
+    return readString(from);
+}
+
+void write(const Store & store, Sink & out, const std::string & str)
+{
+    out << str;
+}
+
+
 StorePath read(const Store & store, Source & from, Phantom<StorePath> _)
 {
     return store.parseStorePath(readString(from));
@@ -76,19 +48,39 @@ void write(const Store & store, Sink & out, const StorePath & storePath)
 }
 
 
-template<>
+ContentAddress read(const Store & store, Source & from, Phantom<ContentAddress> _)
+{
+    return parseContentAddress(readString(from));
+}
+
+void write(const Store & store, Sink & out, const ContentAddress & ca)
+{
+    out << renderContentAddress(ca);
+}
+
+
 std::optional<StorePath> read(const Store & store, Source & from, Phantom<std::optional<StorePath>> _)
 {
     auto s = readString(from);
     return s == "" ? std::optional<StorePath> {} : store.parseStorePath(s);
 }
 
-template<>
 void write(const Store & store, Sink & out, const std::optional<StorePath> & storePathOpt)
 {
     out << (storePathOpt ? store.printStorePath(*storePathOpt) : "");
 }
 
+
+std::optional<ContentAddress> read(const Store & store, Source & from, Phantom<std::optional<ContentAddress>> _)
+{
+    return parseContentAddressOpt(readString(from));
+}
+
+void write(const Store & store, Sink & out, const std::optional<ContentAddress> & caOpt)
+{
+    out << (caOpt ? renderContentAddress(*caOpt) : "");
+}
+
 }
 
 
@@ -337,9 +329,9 @@ StorePathSet RemoteStore::queryValidPaths(const StorePathSet & paths, Substitute
         return res;
     } else {
         conn->to << wopQueryValidPaths;
-        writeStorePaths(*this, conn->to, paths);
+        worker_proto::write(*this, conn->to, paths);
         conn.processStderr();
-        return readStorePaths<StorePathSet>(*this, conn->from);
+        return worker_proto::read(*this, conn->from, Phantom<StorePathSet> {});
     }
 }
 
@@ -349,7 +341,7 @@ StorePathSet RemoteStore::queryAllValidPaths()
     auto conn(getConnection());
     conn->to << wopQueryAllValidPaths;
     conn.processStderr();
-    return readStorePaths<StorePathSet>(*this, conn->from);
+    return worker_proto::read(*this, conn->from, Phantom<StorePathSet> {});
 }
 
 
@@ -366,9 +358,9 @@ StorePathSet RemoteStore::querySubstitutablePaths(const StorePathSet & paths)
         return res;
     } else {
         conn->to << wopQuerySubstitutablePaths;
-        writeStorePaths(*this, conn->to, paths);
+        worker_proto::write(*this, conn->to, paths);
         conn.processStderr();
-        return readStorePaths<StorePathSet>(*this, conn->from);
+        return worker_proto::read(*this, conn->from, Phantom<StorePathSet> {});
     }
 }
 
@@ -390,7 +382,7 @@ void RemoteStore::querySubstitutablePathInfos(const StorePathCAMap & pathsMap, S
             auto deriver = readString(conn->from);
             if (deriver != "")
                 info.deriver = parseStorePath(deriver);
-            info.references = readStorePaths<StorePathSet>(*this, conn->from);
+            info.references = worker_proto::read(*this, conn->from, Phantom<StorePathSet> {});
             info.downloadSize = readLongLong(conn->from);
             info.narSize = readLongLong(conn->from);
             infos.insert_or_assign(i.first, std::move(info));
@@ -403,9 +395,9 @@ void RemoteStore::querySubstitutablePathInfos(const StorePathCAMap & pathsMap, S
             StorePathSet paths;
             for (auto & path : pathsMap)
                 paths.insert(path.first);
-            writeStorePaths(*this, conn->to, paths);
+            worker_proto::write(*this, conn->to, paths);
         } else
-            writeStorePathCAMap(*this, conn->to, pathsMap);
+            worker_proto::write(*this, conn->to, pathsMap);
         conn.processStderr();
         size_t count = readNum<size_t>(conn->from);
         for (size_t n = 0; n < count; n++) {
@@ -413,7 +405,7 @@ void RemoteStore::querySubstitutablePathInfos(const StorePathCAMap & pathsMap, S
             auto deriver = readString(conn->from);
             if (deriver != "")
                 info.deriver = parseStorePath(deriver);
-            info.references = readStorePaths<StorePathSet>(*this, conn->from);
+            info.references = worker_proto::read(*this, conn->from, Phantom<StorePathSet> {});
             info.downloadSize = readLongLong(conn->from);
             info.narSize = readLongLong(conn->from);
         }
@@ -428,7 +420,7 @@ ref<const ValidPathInfo> RemoteStore::readValidPathInfo(ConnectionHandle & conn,
     auto narHash = Hash::parseAny(readString(conn->from), htSHA256);
     auto info = make_ref<ValidPathInfo>(path, narHash);
     if (deriver != "") info->deriver = parseStorePath(deriver);
-    info->references = readStorePaths<StorePathSet>(*this, conn->from);
+    info->references = worker_proto::read(*this, conn->from, Phantom<StorePathSet> {});
     conn->from >> info->registrationTime >> info->narSize;
     if (GET_PROTOCOL_MINOR(conn->daemonVersion) >= 16) {
         conn->from >> info->ultimate;
@@ -472,7 +464,7 @@ void RemoteStore::queryReferrers(const StorePath & path,
     auto conn(getConnection());
     conn->to << wopQueryReferrers << printStorePath(path);
     conn.processStderr();
-    for (auto & i : readStorePaths<StorePathSet>(*this, conn->from))
+    for (auto & i : worker_proto::read(*this, conn->from, Phantom<StorePathSet> {}))
         referrers.insert(i);
 }
 
@@ -482,7 +474,7 @@ StorePathSet RemoteStore::queryValidDerivers(const StorePath & path)
     auto conn(getConnection());
     conn->to << wopQueryValidDerivers << printStorePath(path);
     conn.processStderr();
-    return readStorePaths<StorePathSet>(*this, conn->from);
+    return worker_proto::read(*this, conn->from, Phantom<StorePathSet> {});
 }
 
 
@@ -494,7 +486,7 @@ StorePathSet RemoteStore::queryDerivationOutputs(const StorePath & path)
     }
     conn->to << wopQueryDerivationOutputs << printStorePath(path);
     conn.processStderr();
-    return readStorePaths<StorePathSet>(*this, conn->from);
+    return worker_proto::read(*this, conn->from, Phantom<StorePathSet> {});
 }
 
 
@@ -520,7 +512,6 @@ std::map<std::string, std::optional<StorePath>> RemoteStore::queryPartialDerivat
         }
         return ret;
     }
-
 }
 
 std::optional<StorePath> RemoteStore::queryPathFromHashPart(const std::string & hashPart)
@@ -550,7 +541,7 @@ ref<const ValidPathInfo> RemoteStore::addCAToStore(
             << wopAddToStore
             << name
             << renderContentAddressMethod(caMethod);
-        writeStorePaths(*this, conn->to, references);
+        worker_proto::write(*this, conn->to, references);
         conn->to << repair;
 
         conn.withFramedSink([&](Sink & sink) {
@@ -567,7 +558,7 @@ ref<const ValidPathInfo> RemoteStore::addCAToStore(
             [&](TextHashMethod thm) -> void {
                 std::string s = dump.drain();
                 conn->to << wopAddTextToStore << name << s;
-                writeStorePaths(*this, conn->to, references);
+                worker_proto::write(*this, conn->to, references);
                 conn.processStderr();
             },
             [&](FixedOutputHashMethod fohm) -> void {
@@ -636,7 +627,7 @@ void RemoteStore::addToStore(const ValidPathInfo & info, Source & source,
             sink
                 << exportMagic
                 << printStorePath(info.path);
-            writeStorePaths(*this, sink, info.references);
+            worker_proto::write(*this, sink, info.references);
             sink
                 << (info.deriver ? printStorePath(*info.deriver) : "")
                 << 0 // == no legacy signature
@@ -646,7 +637,7 @@ void RemoteStore::addToStore(const ValidPathInfo & info, Source & source,
 
         conn.processStderr(0, source2.get());
 
-        auto importedPaths = readStorePaths<StorePathSet>(*this, conn->from);
+        auto importedPaths = worker_proto::read(*this, conn->from, Phantom<StorePathSet> {});
         assert(importedPaths.size() <= 1);
     }
 
@@ -655,7 +646,7 @@ void RemoteStore::addToStore(const ValidPathInfo & info, Source & source,
                  << printStorePath(info.path)
                  << (info.deriver ? printStorePath(*info.deriver) : "")
                  << info.narHash.to_string(Base16, false);
-        writeStorePaths(*this, conn->to, info.references);
+        worker_proto::write(*this, conn->to, info.references);
         conn->to << info.registrationTime << info.narSize
                  << info.ultimate << info.sigs << renderContentAddress(info.ca)
                  << repair << !checkSigs;
@@ -777,7 +768,7 @@ void RemoteStore::collectGarbage(const GCOptions & options, GCResults & results)
 
     conn->to
         << wopCollectGarbage << options.action;
-    writeStorePaths(*this, conn->to, options.pathsToDelete);
+    worker_proto::write(*this, conn->to, options.pathsToDelete);
     conn->to << options.ignoreLiveness
         << options.maxFreed
         /* removed options */
@@ -839,9 +830,9 @@ void RemoteStore::queryMissing(const std::vector<StorePathWithOutputs> & targets
             ss.push_back(p.to_string(*this));
         conn->to << ss;
         conn.processStderr();
-        willBuild = readStorePaths<StorePathSet>(*this, conn->from);
+        willBuild = worker_proto::read(*this, conn->from, Phantom<StorePathSet> {});
-        willSubstitute = readStorePaths<StorePathSet>(*this, conn->from);
+        willSubstitute = worker_proto::read(*this, conn->from, Phantom<StorePathSet> {});
-        unknown = readStorePaths<StorePathSet>(*this, conn->from);
+        unknown = worker_proto::read(*this, conn->from, Phantom<StorePathSet> {});
         conn->from >> downloadSize >> narSize;
         return;
     }

src/libstore/worker-protocol.hh

@@ -66,10 +66,6 @@ typedef enum {
 class Store;
 struct Source;
 
-template<class T> T readStorePaths(const Store & store, Source & from);
-
-void writeStorePaths(const Store & store, Sink & out, const StorePathSet & paths);
-
 /* To guide overloading */
 template<typename T>
 struct Phantom {};
@@ -78,45 +74,63 @@ struct Phantom {};
 namespace worker_proto {
 /* FIXME maybe move more stuff inside here */
 
-StorePath read(const Store & store, Source & from, Phantom<StorePath> _);
+#define MAKE_WORKER_PROTO(TEMPLATE, T) \
-void write(const Store & store, Sink & out, const StorePath & storePath);
+    TEMPLATE T read(const Store & store, Source & from, Phantom< T > _); \
+    TEMPLATE void write(const Store & store, Sink & out, const T & str)
+
+MAKE_WORKER_PROTO(, std::string);
+MAKE_WORKER_PROTO(, StorePath);
+MAKE_WORKER_PROTO(, ContentAddress);
+
+MAKE_WORKER_PROTO(template<typename T>, std::set<T>);
+MAKE_WORKER_PROTO(template<typename T>, std::optional<T>);
+
+#define X_ template<typename K, typename V>
+#define Y_ std::map<K, V>
+MAKE_WORKER_PROTO(X_, Y_);
+#undef X_
+#undef Y_
 
 template<typename T>
-std::map<std::string, T> read(const Store & store, Source & from, Phantom<std::map<std::string, T>> _);
+std::set<T> read(const Store & store, Source & from, Phantom<std::set<T>> _)
-template<typename T>
-void write(const Store & store, Sink & out, const std::map<string, T> & resMap);
-template<typename T>
-std::optional<T> read(const Store & store, Source & from, Phantom<std::optional<T>> _);
-template<typename T>
-void write(const Store & store, Sink & out, const std::optional<T> & optVal);
-
-/* Specialization which uses and empty string for the empty case, taking
-   advantage of the fact StorePaths always serialize to a non-empty string.
-   This is done primarily for backwards compatability, so that StorePath <=
-   std::optional<StorePath>, where <= is the compatability partial order.
- */
-template<>
-void write(const Store & store, Sink & out, const std::optional<StorePath> & optVal);
-
-template<typename T>
-std::map<std::string, T> read(const Store & store, Source & from, Phantom<std::map<std::string, T>> _)
 {
-    std::map<string, T> resMap;
+    std::set<T> resSet;
-    auto size = (size_t)readInt(from);
+    auto size = readNum<size_t>(from);
     while (size--) {
-        auto thisKey = readString(from);
+        resSet.insert(read(store, from, Phantom<T> {}));
-        resMap.insert_or_assign(std::move(thisKey), nix::worker_proto::read(store, from, Phantom<T> {}));
+    }
+    return resSet;
+}
+
+template<typename T>
+void write(const Store & store, Sink & out, const std::set<T> & resSet)
+{
+    out << resSet.size();
+    for (auto & key : resSet) {
+        write(store, out, key);
+    }
+}
+
+template<typename K, typename V>
+std::map<K, V> read(const Store & store, Source & from, Phantom<std::map<K, V>> _)
+{
+    std::map<K, V> resMap;
+    auto size = readNum<size_t>(from);
+    while (size--) {
+        auto k = read(store, from, Phantom<K> {});
+        auto v = read(store, from, Phantom<V> {});
+        resMap.insert_or_assign(std::move(k), std::move(v));
     }
     return resMap;
 }
 
-template<typename T>
+template<typename K, typename V>
-void write(const Store & store, Sink & out, const std::map<string, T> & resMap)
+void write(const Store & store, Sink & out, const std::map<K, V> & resMap)
 {
     out << resMap.size();
     for (auto & i : resMap) {
-        out << i.first;
+        write(store, out, i.first);
-        nix::worker_proto::write(store, out, i.second);
+        write(store, out, i.second);
     }
 }
 
@@ -128,26 +142,29 @@ std::optional<T> read(const Store & store, Source & from, Phantom<std::optional<
     case 0:
         return std::nullopt;
     case 1:
-        return nix::worker_proto::read(store, from, Phantom<T> {});
+        return read(store, from, Phantom<T> {});
     default:
-        throw Error("got an invalid tag bit for std::optional: %#04x", tag);
+        throw Error("got an invalid tag bit for std::optional: %#04x", (size_t)tag);
     }
 }
 
 template<typename T>
 void write(const Store & store, Sink & out, const std::optional<T> & optVal)
 {
-    out << (optVal ? 1 : 0);
+    out << (uint64_t) (optVal ? 1 : 0);
     if (optVal)
-        nix::worker_proto::write(store, out, *optVal);
+        worker_proto::write(store, out, *optVal);
 }
 
+/* Specialization which uses and empty string for the empty case, taking
+   advantage of the fact these types always serialize to non-empty strings.
+   This is done primarily for backwards compatability, so that T <=
+   std::optional<T>, where <= is the compatability partial order, T is one of
+   the types below.
+ */
+MAKE_WORKER_PROTO(, std::optional<StorePath>);
+MAKE_WORKER_PROTO(, std::optional<ContentAddress>);
 
 }
 
-
-StorePathCAMap readStorePathCAMap(const Store & store, Source & from);
-
-void writeStorePathCAMap(const Store & store, Sink & out, const StorePathCAMap & paths);
-
 }

src/nix-store/nix-store.cc

@@ -822,7 +822,7 @@ static void opServe(Strings opFlags, Strings opArgs)
             case cmdQueryValidPaths: {
                 bool lock = readInt(in);
                 bool substitute = readInt(in);
-                auto paths = readStorePaths<StorePathSet>(*store, in);
+                auto paths = worker_proto::read(*store, in, Phantom<StorePathSet> {});
                 if (lock && writeAllowed)
                     for (auto & path : paths)
                         store->addTempRoot(path);
@@ -852,19 +852,19 @@ static void opServe(Strings opFlags, Strings opArgs)
                         }
                 }
 
-                writeStorePaths(*store, out, store->queryValidPaths(paths));
+                worker_proto::write(*store, out, store->queryValidPaths(paths));
                 break;
             }
 
             case cmdQueryPathInfos: {
-                auto paths = readStorePaths<StorePathSet>(*store, in);
+                auto paths = worker_proto::read(*store, in, Phantom<StorePathSet> {});
                 // !!! Maybe we want a queryPathInfos?
                 for (auto & i : paths) {
                     try {
                         auto info = store->queryPathInfo(i);
                         out << store->printStorePath(info->path)
                             << (info->deriver ? store->printStorePath(*info->deriver) : "");
-                        writeStorePaths(*store, out, info->references);
+                        worker_proto::write(*store, out, info->references);
                         // !!! Maybe we want compression?
                         out << info->narSize // downloadSize
                             << info->narSize;
@@ -892,7 +892,7 @@ static void opServe(Strings opFlags, Strings opArgs)
 
             case cmdExportPaths: {
                 readInt(in); // obsolete
-                store->exportPaths(readStorePaths<StorePathSet>(*store, in), out);
+                store->exportPaths(worker_proto::read(*store, in, Phantom<StorePathSet> {}), out);
                 break;
             }
 
@@ -941,9 +941,9 @@ static void opServe(Strings opFlags, Strings opArgs)
             case cmdQueryClosure: {
                 bool includeOutputs = readInt(in);
                 StorePathSet closure;
-                store->computeFSClosure(readStorePaths<StorePathSet>(*store, in),
+                store->computeFSClosure(worker_proto::read(*store, in, Phantom<StorePathSet> {}),
                     closure, false, includeOutputs);
-                writeStorePaths(*store, out, closure);
+                worker_proto::write(*store, out, closure);
                 break;
             }
 
@@ -958,7 +958,7 @@ static void opServe(Strings opFlags, Strings opArgs)
                 };
                 if (deriver != "")
                     info.deriver = store->parseStorePath(deriver);
-                info.references = readStorePaths<StorePathSet>(*store, in);
+                info.references = worker_proto::read(*store, in, Phantom<StorePathSet> {});
                 in >> info.registrationTime >> info.narSize >> info.ultimate;
                 info.sigs = readStrings<StringSet>(in);
                 info.ca = parseContentAddressOpt(readString(in));