build-remote: Implement in C++

src/libstore/derivations.cc

@@ -88,9 +88,6 @@ Path writeDerivation(ref<Store> store,
 }
 
 
-MakeError(FormatError, Error)
-
-
 /* Read string `s' from stream `str'. */
 static void expect(std::istream & str, const string & s)
 {

src/libstore/pathlocks.cc

@@ -53,6 +53,8 @@ bool lockFile(int fd, LockType lockType, bool wait)
             checkInterrupt();
             if (errno != EINTR)
                 throw SysError(format("acquiring/releasing lock"));
+            else
+                return false;
         }
     } else {
         while (fcntl(fd, F_SETLK, &lock) != 0) {

src/libstore/ssh-store.cc

@@ -49,6 +49,8 @@ SSHStore::SSHStore(string uri, const Params & params, size_t maxConnections)
     , uri(std::move(uri))
     , key(get(params, "ssh-key", ""))
 {
+    /* open a connection and perform the handshake to verify all is well */
+    connections->get();
 }
 
 string SSHStore::getUri()

src/libstore/store-api.cc

@@ -3,6 +3,7 @@
 #include "store-api.hh"
 #include "util.hh"
 #include "nar-info-disk-cache.hh"
+#include "thread-pool.hh"
 
 #include <future>
 
@@ -698,4 +699,36 @@ std::list<ref<Store>> getDefaultSubstituters()
 }
 
 
+void copyPaths(ref<Store> from, ref<Store> to, const Paths & storePaths)
+{
+    std::string copiedLabel = "copied";
+
+    logger->setExpected(copiedLabel, storePaths.size());
+
+    ThreadPool pool;
+
+    processGraph<Path>(pool,
+        PathSet(storePaths.begin(), storePaths.end()),
+
+        [&](const Path & storePath) {
+            return from->queryPathInfo(storePath)->references;
+        },
+
+        [&](const Path & storePath) {
+            checkInterrupt();
+
+            if (!to->isValidPath(storePath)) {
+                Activity act(*logger, lvlInfo, format("copying ‘%s’...") % storePath);
+
+                copyStorePath(from, to, storePath);
+
+                logger->incProgress(copiedLabel);
+            } else
+                logger->incExpected(copiedLabel, -1);
+        });
+
+    pool.process();
+}
+
+
 }

src/libstore/store-api.hh

@@ -608,6 +608,8 @@ void removeTempRoots();
 ref<Store> openStore(const std::string & uri = getEnv("NIX_REMOTE"));
 
 
+void copyPaths(ref<Store> from, ref<Store> to, const Paths & storePaths);
+
 enum StoreType {
     tDaemon,
     tLocal,