Merge pull request #3859 from obsidiansystems/drv-outputs-map-allow-missing

`queryDerivationOutputMap` no longer assumes all outputs have a mapping

src/libstore/build.cc

@@ -2756,8 +2756,12 @@ struct RestrictedStore : public LocalFSStore
     void queryReferrers(const StorePath & path, StorePathSet & referrers) override
     { }
 
-    OutputPathMap queryDerivationOutputMap(const StorePath & path) override
-    { throw Error("queryDerivationOutputMap"); }
+    std::map<std::string, std::optional<StorePath>> queryPartialDerivationOutputMap(const StorePath & path) override
+    {
+        if (!goal.isAllowed(path))
+            throw InvalidPath("cannot query output map for unknown path '%s' in recursive Nix", printStorePath(path));
+        return next->queryPartialDerivationOutputMap(path);
+    }
 
     std::optional<StorePath> queryPathFromHashPart(const std::string & hashPart) override
     { throw Error("queryPathFromHashPart"); }
@@ -4983,7 +4987,7 @@ void Worker::waitForInput()
         std::vector<unsigned char> buffer(4096);
         for (auto & k : fds2) {
             if (pollStatus.at(fdToPollStatus.at(k)).revents) {
-                ssize_t rd = read(k, buffer.data(), buffer.size());
+                ssize_t rd = ::read(k, buffer.data(), buffer.size());
                 // FIXME: is there a cleaner way to handle pt close
                 // than EIO? Is this even standard?
                 if (rd == 0 || (rd == -1 && errno == EIO)) {

src/libstore/daemon.cc

@@ -325,9 +325,9 @@ static void performOp(TunnelLogger * logger, ref<Store> store,
     case wopQueryDerivationOutputMap: {
         auto path = store->parseStorePath(readString(from));
         logger->startWork();
-        OutputPathMap outputs = store->queryDerivationOutputMap(path);
+        auto outputs = store->queryPartialDerivationOutputMap(path);
         logger->stopWork();
-        writeOutputPathMap(*store, to, outputs);
+        worker_proto::write(*store, to, outputs);
         break;
     }
 

src/libstore/local-store.cc

@@ -785,17 +785,21 @@ StorePathSet LocalStore::queryValidDerivers(const StorePath & path)
 }
 
 
-OutputPathMap LocalStore::queryDerivationOutputMap(const StorePath & path)
+std::map<std::string, std::optional<StorePath>> LocalStore::queryPartialDerivationOutputMap(const StorePath & path)
 {
-    return retrySQLite<OutputPathMap>([&]() {
+    std::map<std::string, std::optional<StorePath>> outputs;
+    BasicDerivation drv = readDerivation(path);
+    for (auto & [outName, _] : drv.outputs) {
+        outputs.insert_or_assign(outName, std::nullopt);
+    }
+    return retrySQLite<std::map<std::string, std::optional<StorePath>>>([&]() {
         auto state(_state.lock());
 
         auto useQueryDerivationOutputs(state->stmtQueryDerivationOutputs.use()
             (queryValidPathId(*state, path)));
 
-        OutputPathMap outputs;
         while (useQueryDerivationOutputs.next())
-            outputs.emplace(
+            outputs.insert_or_assign(
                 useQueryDerivationOutputs.getStr(0),
                 parseStorePath(useQueryDerivationOutputs.getStr(1))
             );

src/libstore/local-store.hh

@@ -133,7 +133,7 @@ public:
 
     StorePathSet queryValidDerivers(const StorePath & path) override;
 
-    OutputPathMap queryDerivationOutputMap(const StorePath & path) override;
+    std::map<std::string, std::optional<StorePath>> queryPartialDerivationOutputMap(const StorePath & path) override;
 
     std::optional<StorePath> queryPathFromHashPart(const std::string & hashPart) override;
 

src/libstore/remote-store.cc

@@ -31,7 +31,6 @@ template<> StorePathSet readStorePaths(const Store & store, Source & from)
     return paths;
 }
 
-
 void writeStorePaths(const Store & store, Sink & out, const StorePathSet & paths)
 {
     out << paths.size();
@@ -39,6 +38,7 @@ void writeStorePaths(const Store & store, Sink & out, const StorePathSet & paths
         out << store.printStorePath(i);
 }
 
+
 StorePathCAMap readStorePathCAMap(const Store & store, Source & from)
 {
     StorePathCAMap paths;
@@ -57,30 +57,36 @@ void writeStorePathCAMap(const Store & store, Sink & out, const StorePathCAMap &
     }
 }
 
-std::map<string, StorePath> readOutputPathMap(const Store & store, Source & from)
+
+namespace worker_proto {
+
+StorePath read(const Store & store, Source & from, Phantom<StorePath> _)
 {
-    std::map<string, StorePath> pathMap;
-    auto rawInput = readStrings<Strings>(from);
-    if (rawInput.size() % 2)
-        throw Error("got an odd number of elements from the daemon when trying to read a output path map");
-    auto curInput = rawInput.begin();
-    while (curInput != rawInput.end()) {
-        auto thisKey = *curInput++;
-        auto thisValue = *curInput++;
-        pathMap.emplace(thisKey, store.parseStorePath(thisValue));
-    }
-    return pathMap;
+    return store.parseStorePath(readString(from));
 }
 
-void writeOutputPathMap(const Store & store, Sink & out, const std::map<string, StorePath> & pathMap)
+void write(const Store & store, Sink & out, const StorePath & storePath)
 {
-    out << 2*pathMap.size();
-    for (auto & i : pathMap) {
-        out << i.first;
-        out << store.printStorePath(i.second);
+    out << store.printStorePath(storePath);
 }
+
+
+template<>
+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) : "");
+}
+
+}
+
+
 /* TODO: Separate these store impls into different files, give them better names */
 RemoteStore::RemoteStore(const Params & params)
     : Store(params)
@@ -468,12 +474,12 @@ StorePathSet RemoteStore::queryDerivationOutputs(const StorePath & path)
 }
 
 
-OutputPathMap RemoteStore::queryDerivationOutputMap(const StorePath & path)
+std::map<std::string, std::optional<StorePath>> RemoteStore::queryPartialDerivationOutputMap(const StorePath & path)
 {
     auto conn(getConnection());
     conn->to << wopQueryDerivationOutputMap << printStorePath(path);
     conn.processStderr();
-    return readOutputPathMap(*this, conn->from);
+    return worker_proto::read(*this, conn->from, Phantom<std::map<std::string, std::optional<StorePath>>> {});
 
 }
 

src/libstore/remote-store.hh

@@ -51,7 +51,7 @@ public:
 
     StorePathSet queryDerivationOutputs(const StorePath & path) override;
 
-    OutputPathMap queryDerivationOutputMap(const StorePath & path) override;
+    std::map<std::string, std::optional<StorePath>> queryPartialDerivationOutputMap(const StorePath & path) override;
     std::optional<StorePath> queryPathFromHashPart(const std::string & hashPart) override;
 
     StorePathSet querySubstitutablePaths(const StorePathSet & paths) override;

src/libstore/store-api.cc

@@ -359,6 +359,17 @@ bool Store::PathInfoCacheValue::isKnownNow()
     return std::chrono::steady_clock::now() < time_point + ttl;
 }
 
+OutputPathMap Store::queryDerivationOutputMap(const StorePath & path) {
+    auto resp = queryPartialDerivationOutputMap(path);
+    OutputPathMap result;
+    for (auto & [outName, optOutPath] : resp) {
+        if (!optOutPath)
+            throw Error("output '%s' has no store path mapped to it", outName);
+        result.insert_or_assign(outName, *optOutPath);
+    }
+    return result;
+}
+
 StorePathSet Store::queryDerivationOutputs(const StorePath & path)
 {
     auto outputMap = this->queryDerivationOutputMap(path);

src/libstore/store-api.hh

@@ -343,9 +343,15 @@ public:
     /* Query the outputs of the derivation denoted by `path'. */
     virtual StorePathSet queryDerivationOutputs(const StorePath & path);
 
-    /* Query the mapping outputName=>outputPath for the given derivation */
-    virtual OutputPathMap queryDerivationOutputMap(const StorePath & path)
-    { unsupported("queryDerivationOutputMap"); }
+    /* Query the mapping outputName => outputPath for the given derivation. All
+       outputs are mentioned so ones mising the mapping are mapped to
+       `std::nullopt`.  */
+    virtual std::map<std::string, std::optional<StorePath>> queryPartialDerivationOutputMap(const StorePath & path)
+    { unsupported("queryPartialDerivationOutputMap"); }
+
+    /* Query the mapping outputName=>outputPath for the given derivation.
+       Assume every output has a mapping and throw an exception otherwise. */
+    OutputPathMap queryDerivationOutputMap(const StorePath & path);
 
     /* Query the full store path given the hash part of a valid store
        path, or empty if the path doesn't exist. */

src/libstore/worker-protocol.hh

@@ -70,10 +70,84 @@ 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 {};
+
+
+namespace worker_proto {
+/* FIXME maybe move more stuff inside here */
+
+StorePath read(const Store & store, Source & from, Phantom<StorePath> _);
+void write(const Store & store, Sink & out, const StorePath & storePath);
+
+template<typename T>
+std::map<std::string, T> read(const Store & store, Source & from, Phantom<std::map<std::string, 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;
+    auto size = (size_t)readInt(from);
+    while (size--) {
+        auto thisKey = readString(from);
+        resMap.insert_or_assign(std::move(thisKey), nix::worker_proto::read(store, from, Phantom<T> {}));
+    }
+    return resMap;
+}
+
+template<typename T>
+void write(const Store & store, Sink & out, const std::map<string, T> & resMap)
+{
+    out << resMap.size();
+    for (auto & i : resMap) {
+        out << i.first;
+        nix::worker_proto::write(store, out, i.second);
+    }
+}
+
+template<typename T>
+std::optional<T> read(const Store & store, Source & from, Phantom<std::optional<T>> _)
+{
+    auto tag = readNum<uint8_t>(from);
+    switch (tag) {
+    case 0:
+        return std::nullopt;
+    case 1:
+        return nix::worker_proto::read(store, from, Phantom<T> {});
+    default:
+        throw Error("got an invalid tag bit for std::optional: %#04x", tag);
+    }
+}
+
+template<typename T>
+void write(const Store & store, Sink & out, const std::optional<T> & optVal)
+{
+    out << (optVal ? 1 : 0);
+    if (optVal)
+        nix::worker_proto::write(store, out, *optVal);
+}
+
+
+}
+
+
 StorePathCAMap readStorePathCAMap(const Store & store, Source & from);
 
 void writeStorePathCAMap(const Store & store, Sink & out, const StorePathCAMap & paths);
 
-void writeOutputPathMap(const Store & store, Sink & out, const OutputPathMap & paths);
-
 }