S3BinaryCacheStore:: Eliminate a string copy while uploading

This cuts hydra-queue-runner's peak memory usage by about a third.

2 files changed, 2 insertions, 2 deletions

diff --git a/src/libstore/derivations.cc b/src/libstore/derivations.cc
index d934bda38225..5562d46892a8 100644
--- a/src/libstore/derivations.cc
+++ b/src/libstore/derivations.cc
@@ -155,7 +155,7 @@ static StringSet parseStrings(std::istream & str, bool arePaths)
 static Derivation parseDerivation(const string & s)
 {
     Derivation drv;
-    std::istringstream str(s);
+    istringstream_nocopy str(s);
     expect(str, "Derive([");
 
     /* Parse the list of outputs. */
diff --git a/src/libstore/s3-binary-cache-store.cc b/src/libstore/s3-binary-cache-store.cc
index c11f2b06b990..1bc8576a8aef 100644
--- a/src/libstore/s3-binary-cache-store.cc
+++ b/src/libstore/s3-binary-cache-store.cc
@@ -145,7 +145,7 @@ struct S3BinaryCacheStoreImpl : public S3BinaryCacheStore
             .WithBucket(bucketName)
             .WithKey(path);
 
-        auto stream = std::make_shared<std::stringstream>(data);
+        auto stream = std::make_shared<istringstream_nocopy>(data);
 
         request.SetBody(stream);