experiment: enable tokio eager driver handoff (3.7.0 follow-up)

.cargo/config.toml

@@ -0,0 +1,2 @@
+[build]
+rustflags = ["--cfg", "tokio_unstable"]

debian/rules

@@ -3,6 +3,11 @@
 export DH_VERBOSE = 1
 export JEMALLOC_SYS_WITH_MALLOC_CONF = dirty_decay_ms:30000,muzzy_decay_ms:30000,background_thread:true,metadata_thp:auto
 
+# Required by tokio::runtime::Builder::enable_eager_driver_handoff (unstable API).
+# The .cargo/config.toml in the source tree is overwritten below in override_dh_auto_build
+# to point at vendored sources, so we re-deliver the cfg via RUSTFLAGS here.
+export RUSTFLAGS = --cfg tokio_unstable
+
 # Rust installation directory (local install, no network access on Launchpad)
 RUST_INSTALL_DIR = $(CURDIR)/rust-local
 export PATH := $(RUST_INSTALL_DIR)/bin:$(PATH)

pkg/rpm/pg-doorman.spec

@@ -62,6 +62,11 @@ EOF
 # Set jemalloc configuration
 export JEMALLOC_SYS_WITH_MALLOC_CONF="dirty_decay_ms:30000,muzzy_decay_ms:30000,background_thread:true,metadata_thp:auto"
 
+# Required by tokio::runtime::Builder::enable_eager_driver_handoff (unstable API).
+# The .cargo/config.toml shipped in the source tree is overwritten above to point
+# at vendored sources, so we re-deliver the cfg via RUSTFLAGS here.
+export RUSTFLAGS="--cfg tokio_unstable"
+
 # Build release binaries
 cargo build --release
 

src/app/server.rs

@@ -92,6 +92,7 @@ pub fn run_server(args: Args, config: Config) -> Result<(), Box<dyn std::error::
     runtime_builder
         .worker_threads(config.general.worker_threads)
         .enable_all()
+        .enable_eager_driver_handoff()
         .thread_name("worker-pg-doorman");
 
     // Apply optional tokio runtime parameters only if explicitly configured.