libutil: begin porting serialization to generators

generators are a better basis for serializers than streaming into sinks
as we do currently for many reasons, such as being usable as sources if
one wishes to (without requiring an intermediate sink to serialize full
data sets into memory, or boost coroutines to turn sinks into sources),
composing more naturally (as one can just yield a sub-generator instead
of being forced to wrap entire substreams into clunky functions or even
more clunky custom types to implement operator<< on), allowing wrappers
to transform data with clear ownership semantics (removing the need for
explicit memory allocations and Source wrappers), and many other things

Change-Id: I361d89ff556354f6930d9204f55117565f2f7f20

2 files changed, 2 insertions, 3 deletions

diff --git a/src/libstore/daemon.cc b/src/libstore/daemon.cc
index 6d64644d1..cdc9c09c7 100644
--- a/src/libstore/daemon.cc
+++ b/src/libstore/daemon.cc
@@ -160,8 +160,7 @@ struct TunnelSink : Sink
     TunnelSink(Sink & to) : to(to) { }
     void operator () (std::string_view data)
     {
-        to << STDERR_WRITE;
-        writeString(data, to);
+        to << STDERR_WRITE << data;
     }
 };
 
diff --git a/src/libstore/remote-store.cc b/src/libstore/remote-store.cc
index b2f8a285d..55a71f502 100644
--- a/src/libstore/remote-store.cc
+++ b/src/libstore/remote-store.cc
@@ -897,7 +897,7 @@ std::exception_ptr RemoteStore::Connection::processStderr(Sink * sink, Source *
             if (!source) throw Error("no source");
             size_t len = readNum<size_t>(from);
             auto buf = std::make_unique<char[]>(len);
-            writeString({(const char *) buf.get(), source->read(buf.get(), len)}, to);
+            to << std::string_view((const char *) buf.get(), source->read(buf.get(), len));
             to.flush();
         }