partial block fetch (#298)

 - Improvement: Do partial requests of blocks if not all of the block is needed
  - Improvement: Better progress/statistics on download
  - Bugfix: Ensure that temporary folder for Jupiter downloads exists during verify phase

1 files changed, 13 insertions, 4 deletions

diff --git a/src/zenutil/filebuildstorage.cpp b/src/zenutil/filebuildstorage.cpp
index a4bb759e7..e57109006 100644
--- a/src/zenutil/filebuildstorage.cpp
+++ b/src/zenutil/filebuildstorage.cpp
@@ -325,7 +325,7 @@ public:
 		return {};
 	}
 
-	virtual IoBuffer GetBuildBlob(const Oid& BuildId, const IoHash& RawHash) override
+	virtual IoBuffer GetBuildBlob(const Oid& BuildId, const IoHash& RawHash, uint64_t RangeOffset, uint64_t RangeBytes) override
 	{
 		ZEN_UNUSED(BuildId);
 		SimulateLatency(0, 0);
@@ -337,10 +337,19 @@ public:
 		if (std::filesystem::is_regular_file(BlockPath))
 		{
 			BasicFile File(BlockPath, BasicFile::Mode::kRead);
-			IoBuffer  Payload = File.ReadAll();
-			ZEN_ASSERT_SLOW(ValidateCompressedBuffer(RawHash, CompositeBuffer(SharedBuffer(Payload))));
-			m_Stats.TotalBytesRead += Payload.GetSize();
+			IoBuffer  Payload;
+			if (RangeOffset != 0 || RangeBytes != (uint64_t)-1)
+			{
+				Payload = IoBuffer(RangeBytes);
+				File.Read(Payload.GetMutableView().GetData(), RangeBytes, RangeOffset);
+			}
+			else
+			{
+				Payload = File.ReadAll();
+				ZEN_ASSERT_SLOW(ValidateCompressedBuffer(RawHash, CompositeBuffer(SharedBuffer(Payload))));
+			}
 			Payload.SetContentType(ZenContentType::kCompressedBinary);
+			m_Stats.TotalBytesRead += Payload.GetSize();
 			SimulateLatency(0, Payload.GetSize());
 			return Payload;
 		}