From e06061e4e92d37cade77769c44091f6ada1cf298 Mon Sep 17 00:00:00 2001
From: John Ericson <John.Ericson@Obsidian.Systems>
Date: Sun, 20 Feb 2022 19:24:07 +0000
Subject: [PATCH] Start factoring out the serve protocol for Hydra to share

Hydra uses the lock argument differently than Nix, so we un-hard-code
it.

The parent commit is chosen such that this should work for 2.6 and
master alike.
---
 src/libstore/legacy-ssh-store.cc    | 17 ++++-------------
 src/libstore/serve-protocol-impl.cc | 24 ++++++++++++++++++++++++
 src/libstore/serve-protocol-impl.hh | 25 +++++++++++++++++++++++++
 3 files changed, 53 insertions(+), 13 deletions(-)
 create mode 100644 src/libstore/serve-protocol-impl.cc
 create mode 100644 src/libstore/serve-protocol-impl.hh

diff --git a/src/libstore/legacy-ssh-store.cc b/src/libstore/legacy-ssh-store.cc
index 6b3daae7f14..b1797ac3fbb 100644
--- a/src/libstore/legacy-ssh-store.cc
+++ b/src/libstore/legacy-ssh-store.cc
@@ -2,6 +2,7 @@
 #include "pool.hh"
 #include "remote-store.hh"
 #include "serve-protocol.hh"
+#include "serve-protocol-impl.hh"
 #include "store-api.hh"
 #include "path-with-outputs.hh"
 #include "worker-protocol.hh"
@@ -31,12 +32,9 @@ struct LegacySSHStore : public virtual LegacySSHStoreConfig, public virtual Stor
     // the documentation
     const Setting<int> logFD{(StoreConfig*) this, -1, "log-fd", "file descriptor to which SSH's stderr is connected"};
 
-    struct Connection
+    struct Connection : public serve_proto::BasicConnection
     {
         std::unique_ptr<SSHMaster::Connection> sshConn;
-        FdSink to;
-        FdSource from;
-        int remoteVersion;
         bool good = true;
     };
 
@@ -353,15 +351,8 @@ struct LegacySSHStore : public virtual LegacySSHStoreConfig, public virtual Stor
         SubstituteFlag maybeSubstitute = NoSubstitute) override
     {
         auto conn(connections->get());
-
-        conn->to
-            << cmdQueryValidPaths
-            << false // lock
-            << maybeSubstitute;
-        worker_proto::write(*this, conn->to, paths);
-        conn->to.flush();
-
-        return worker_proto::read(*this, conn->from, Phantom<StorePathSet> {});
+        return serve_proto::queryValidPaths(*conn, *this,
+            false, paths, maybeSubstitute);
     }
 
     void connect() override
diff --git a/src/libstore/serve-protocol-impl.cc b/src/libstore/serve-protocol-impl.cc
new file mode 100644
index 00000000000..636d0ce1c87
--- /dev/null
+++ b/src/libstore/serve-protocol-impl.cc
@@ -0,0 +1,24 @@
+#include "serve-protocol-impl.hh"
+
+#include "remote-store.hh"
+
+namespace nix {
+namespace serve_proto {
+
+StorePathSet queryValidPaths(
+    BasicConnection & conn, const Store & remoteStore,
+    bool lock, const StorePathSet & paths,
+    SubstituteFlag maybeSubstitute)
+{
+    conn.to
+        << cmdQueryValidPaths
+        << lock
+        << maybeSubstitute;
+    worker_proto::write(remoteStore, conn.to, paths);
+    conn.to.flush();
+
+    return worker_proto::read(remoteStore, conn.from, Phantom<StorePathSet> {});
+}
+
+}
+}
diff --git a/src/libstore/serve-protocol-impl.hh b/src/libstore/serve-protocol-impl.hh
new file mode 100644
index 00000000000..f0f78c9c0c8
--- /dev/null
+++ b/src/libstore/serve-protocol-impl.hh
@@ -0,0 +1,25 @@
+#pragma once
+
+#include "serialise.hh"
+
+#include "store-api.hh"
+#include "serve-protocol.hh"
+#include "worker-protocol.hh"
+
+namespace nix {
+namespace serve_proto {
+
+struct BasicConnection
+{
+    FdSink to;
+    FdSource from;
+    int remoteVersion;
+};
+
+StorePathSet queryValidPaths(
+    BasicConnection & conn, const Store & remoteStore,
+    bool lock, const StorePathSet & paths,
+    SubstituteFlag maybeSubstitute);
+
+}
+}