zen build cache service (#318)

- **EXPERIMENTAL** `zen builds`
  - Feature: `--zen-cache-host` option for `upload` and `download` operations to use a zenserver host `/builds` endpoint for storing build blob and blob metadata
  - Feature: New `/builds` endpoint for caching build blobs and blob metadata
    - `/builds/{namespace}/{bucket}/{buildid}/blobs/{hash}` `GET` and `PUT` method for storing and fetching blobs
    - `/builds/{namespace}/{bucket}/{buildid}/blobs/putBlobMetadata` `POST` method for storing metadata about blobs
    - `/builds/{namespace}/{bucket}/{buildid}/blobs/getBlobMetadata` `POST` method for fetching metadata about blobs
    - `/builds/{namespace}/{bucket}/{buildid}/blobs/exists` `POST` method for checking existance of blobs

1 files changed, 17 insertions, 10 deletions

diff --git a/src/zenutil/filebuildstorage.cpp b/src/zenutil/filebuildstorage.cpp
index 130fec355..f040e9ece 100644
--- a/src/zenutil/filebuildstorage.cpp
+++ b/src/zenutil/filebuildstorage.cpp
@@ -442,18 +442,19 @@ public:
 		SimulateLatency(0, 0);
 	}
 
-	virtual std::vector<ChunkBlockDescription> FindBlocks(const Oid& BuildId) override
+	virtual CbObject FindBlocks(const Oid& BuildId) override
 	{
 		ZEN_TRACE_CPU("FileBuildStorage::FindBlocks");
 		ZEN_UNUSED(BuildId);
-		SimulateLatency(0, 0);
+		SimulateLatency(sizeof(BuildId), 0);
 		Stopwatch ExecutionTimer;
 		auto	  _ = MakeGuard([&]() { m_Stats.TotalExecutionTimeUs += ExecutionTimer.GetElapsedTimeUs(); });
 		m_Stats.TotalRequestCount++;
 
 		DirectoryContent Content;
 		GetDirectoryContent(GetBlobsMetadataFolder(), DirectoryContentFlags::IncludeFiles, Content);
-		std::vector<ChunkBlockDescription> Result;
+		CbObjectWriter Writer;
+		Writer.BeginArray("blocks");
 		for (const std::filesystem::path& MetaDataFile : Content.Files)
 		{
 			IoHash ChunkHash;
@@ -467,24 +468,28 @@ public:
 					m_Stats.TotalBytesRead += BlockMetaDataPayload.GetSize();
 
 					CbObject BlockObject = CbObject(SharedBuffer(BlockMetaDataPayload));
-					Result.emplace_back(ParseChunkBlockDescription(BlockObject));
+					Writer.AddObject(BlockObject);
 				}
 			}
 		}
-		SimulateLatency(0, sizeof(IoHash) * Result.size());
+		Writer.EndArray();	// blocks
+		CbObject Result = Writer.Save();
+		SimulateLatency(0, Result.GetSize());
 		return Result;
 	}
 
-	virtual std::vector<ChunkBlockDescription> GetBlockMetadata(const Oid& BuildId, std::span<const IoHash> BlockHashes) override
+	virtual CbObject GetBlockMetadatas(const Oid& BuildId, std::span<const IoHash> BlockHashes) override
 	{
 		ZEN_TRACE_CPU("FileBuildStorage::GetBlockMetadata");
 		ZEN_UNUSED(BuildId);
-		SimulateLatency(0, 0);
+		SimulateLatency(sizeof(Oid) + sizeof(IoHash) * BlockHashes.size(), 0);
 		Stopwatch ExecutionTimer;
 		auto	  _ = MakeGuard([&]() { m_Stats.TotalExecutionTimeUs += ExecutionTimer.GetElapsedTimeUs(); });
 		m_Stats.TotalRequestCount++;
 
-		std::vector<ChunkBlockDescription> Result;
+		CbObjectWriter Writer;
+		Writer.BeginArray("blocks");
+
 		for (const IoHash& BlockHash : BlockHashes)
 		{
 			std::filesystem::path MetaDataFile = GetBlobMetadataPath(BlockHash);
@@ -495,10 +500,12 @@ public:
 				m_Stats.TotalBytesRead += BlockMetaDataPayload.GetSize();
 
 				CbObject BlockObject = CbObject(SharedBuffer(BlockMetaDataPayload));
-				Result.emplace_back(ParseChunkBlockDescription(BlockObject));
+				Writer.AddObject(BlockObject);
 			}
 		}
-		SimulateLatency(sizeof(BlockHashes) * BlockHashes.size(), sizeof(ChunkBlockDescription) * Result.size());
+		Writer.EndArray();	// blocks
+		CbObject Result = Writer.Save();
+		SimulateLatency(0, Result.GetSize());
 		return Result;
 	}