fix(tvix): Chunk the AddTextToStore request r/1736

Rather than sending the entire AddTextToStore request along in a single
message, send it in a stream of chunks using the same metadata-first
approach we've been using for the other store gRPC requests. This fixes
a bug where certain builds could send more data than the maximum gRPC
request size (4194304 bytes, it would appear), resulting in a
RESOURCE_EXHAUSTED error.

The initial chunk size, which is currently constant but should be made
dynamic at some point in the future, has been chosen based on the IPC
bandwidth delay product for tazjin's desktop, rounded up.

Change-Id: I6f0232cdbc98653484816b39855126873fc59a03
Reviewed-on: https://cl.tvl.fyi/c/depot/+/1835
Tested-by: BuildkiteCI
Reviewed-by: tazjin <mail@tazj.in>
Reviewed-by: kanepyork <rikingcoding@gmail.com>

1 files changed, 11 insertions, 4 deletions

diff --git a/third_party/nix/src/proto/worker.proto b/third_party/nix/src/proto/worker.proto
index 6a80b3e32b..b0dc32afbe 100644
--- a/third_party/nix/src/proto/worker.proto
+++ b/third_party/nix/src/proto/worker.proto
@@ -23,7 +23,7 @@ service WorkerService {
   rpc AddToStore(stream AddToStoreRequest) returns (StorePath);
 
   // Adds the supplied string to the store, as a text file.
-  rpc AddTextToStore(AddTextToStoreRequest) returns (StorePath);
+  rpc AddTextToStore(stream AddTextToStoreRequest) returns (StorePath);
 
   // Build the specified derivations in one of the specified build
   // modes, defaulting to a normal build.
@@ -223,9 +223,16 @@ message AddToStoreRequest {
 }
 
 message AddTextToStoreRequest {
-  string name = 1;
-  string content = 2;
-  repeated string references = 3;
+  message Metadata {
+    string name = 1;
+    repeated string references = 2;
+    uint64 size = 3;
+  }
+
+  oneof add_oneof {
+    Metadata meta = 4;
+    bytes data = 5;
+  }
 }
 
 message BuildPathsRequest {