libstore: add worker serializer for SubstitutablePathInfo

the test is for the map that usually wraps it though because it's the
bit we're interested in replacing, and it has custom serializer code.

Change-Id: If77a236dfca738b646ed2b7a5c65515dad6b7295

lix/libstore/daemon.cc

@@ -682,13 +682,7 @@ static void performOp(AsyncIoRoot & aio, TunnelLogger * logger, ref<Store> store
         logger->startWork();
         aio.blockOn(store->querySubstitutablePathInfos(pathsMap, infos));
         logger->stopWork();
-        to << infos.size();
-        for (auto & i : infos) {
-            to << store->printStorePath(i.first)
-               << (i.second.deriver ? store->printStorePath(*i.second.deriver) : "");
-            to << WorkerProto::write(*store, wconn, i.second.references);
-            to << i.second.downloadSize << i.second.narSize;
-        }
+        to << WorkerProto::write(*store, wconn, infos);
         break;
     }
 

lix/libstore/path-info.hh

@@ -27,6 +27,9 @@ struct SubstitutablePathInfo
      * 0 = unknown
      */
     uint64_t narSize;
+
+    bool operator==(const SubstitutablePathInfo &) const = default;
+    bool operator!=(const SubstitutablePathInfo &) const = default;
 };
 
 using SubstitutablePathInfos = std::map<StorePath, SubstitutablePathInfo>;

lix/libstore/remote-store.cc

@@ -23,6 +23,7 @@
 #include "lix/libutil/thread-name.hh"
 #include "lix/libutil/thread-pool.hh"
 #include "lix/libutil/types.hh"
+#include "path-info.hh"
 
 #include <kj/async.h>
 #include <optional>
@@ -240,17 +241,7 @@ try {
     conn->to << WorkerProto::Op::QuerySubstitutablePathInfos;
     conn->to << WorkerProto::write(*this, *conn, pathsMap);
     conn.processStderr();
-    size_t count = readNum<size_t>(conn->from);
-    for (size_t n = 0; n < count; n++) {
-        SubstitutablePathInfo & info(infos[parseStorePath(readString(conn->from))]);
-        auto deriver = readString(conn->from);
-        if (deriver != "")
-            info.deriver = parseStorePath(deriver);
-        info.references = WorkerProto::Serialise<StorePathSet>::read(*this, *conn);
-        info.downloadSize = readLongLong(conn->from);
-        info.narSize = readLongLong(conn->from);
-    }
-
+    infos = WorkerProto::Serialise<SubstitutablePathInfos>::read(*this, *conn);
     co_return result::success();
 } catch (...) {
     co_return result::current_exception();

lix/libstore/worker-protocol.cc

@@ -152,4 +152,25 @@ WireFormatGenerator WorkerProto::Serialise<UnkeyedValidPathInfo>::write(const St
     co_yield renderContentAddress(pathInfo.ca);
 }
 
+
+SubstitutablePathInfo WorkerProto::Serialise<SubstitutablePathInfo>::read(const Store & store, ReadConn conn)
+{
+    SubstitutablePathInfo info;
+    auto deriver = readString(conn.from);
+    if (deriver != "")
+        info.deriver = store.parseStorePath(deriver);
+    info.references = WorkerProto::Serialise<StorePathSet>::read(store, conn);
+    info.downloadSize = readLongLong(conn.from);
+    info.narSize = readLongLong(conn.from);
+    return info;
+}
+
+WireFormatGenerator WorkerProto::Serialise<SubstitutablePathInfo>::write(const Store & store, WriteConn conn, const SubstitutablePathInfo & info)
+{
+    co_yield (info.deriver ? store.printStorePath(*info.deriver) : "");
+    co_yield WorkerProto::write(store, conn, info.references);
+    co_yield info.downloadSize;
+    co_yield info.narSize;
+}
+
 }

lix/libstore/worker-protocol.hh

@@ -2,6 +2,7 @@
 ///@file
 
 #include "lix/libstore/common-protocol.hh"
+#include "path-info.hh"
 
 namespace nix {
 
@@ -230,6 +231,8 @@ template<>
 DECLARE_WORKER_SERIALISER(UnkeyedValidPathInfo);
 template<>
 DECLARE_WORKER_SERIALISER(std::optional<TrustedFlag>);
+template<>
+DECLARE_WORKER_SERIALISER(SubstitutablePathInfo);
 
 template<typename T>
 DECLARE_WORKER_SERIALISER(std::vector<T>);

tests/unit/libstore/worker-protocol.cc

@@ -3,6 +3,7 @@
 #include <gtest/gtest.h>
 
 #include "lix/libstore/worker-protocol.hh"
+#include "lix/libstore/path-info.hh"
 #include "lix/libstore/worker-protocol-impl.hh"
 #include "lix/libstore/derived-path.hh"
 #include "lix/libstore/build-result.hh"
@@ -283,4 +284,36 @@ VERSIONED_CHARACTERIZATION_TEST(
         },
     }))
 
+VERSIONED_CHARACTERIZATION_TEST(
+    WorkerProtoTest,
+    substitutablePathInfos,
+    "substitutable-path-infos",
+    defaultVersion,
+    (SubstitutablePathInfos{
+        {StorePath{
+             "g1w7hyyyy1w7hy3qg1w7hy3qgqqqqy3q-foo",
+         },
+         SubstitutablePathInfo{
+             std::nullopt,
+             {},
+             123456789,
+             987654321,
+         }},
+        {StorePath{
+             "g1w7hyyyy1w7hy3qg1w7hy3qgqqqqy3q-bar",
+         },
+         SubstitutablePathInfo{
+             StorePath{
+                 "g1w7hyyyy1w7hy3qg1w7hy3qgqqqqy3q-fox",
+             },
+             {
+                 StorePath{
+                     "g1w7hyyyy1w7hy3qg1w7hy3qgqqqqy3q-other",
+                 },
+             },
+             987654321,
+             123456789,
+         }},
+    })
+)
 }