netlink: use features for slog and agent handler

Use features to enable/disable slog and agent handler on demand.
This helps to reduce dependency chains if slog/agent handler is unused.

Signed-off-by: Liu Jiang <gerry@linux.alibaba.com>

src/agent/Cargo.lock

@@ -257,8 +257,6 @@ dependencies = [
  "protocols",
  "scan_fmt",
  "slog",
- "slog-async",
- "slog-json",
  "slog-scope",
 ]
 

src/agent/netlink/Cargo.toml

@@ -9,10 +9,13 @@ edition = "2018"
 [dependencies]
 libc = "0.2.58"
 nix = "0.17.0"
-protobuf = "=2.14.0"
-protocols = { path = "../protocols" }
-slog = { version = "2.5.2", features = ["dynamic-keys", "max_level_trace", "release_max_level_info"] }
-slog-json = "2.3.0"
-slog-async = "2.3.0"
-slog-scope = "4.1.2"
+
+protobuf = { version = "=2.14.0", optional = true }
+protocols = { path = "../protocols", optional = true }
+slog = { version = "2.5.2", features = ["dynamic-keys", "max_level_trace", "release_max_level_info"], optional = true }
+slog-scope = { version = "4.1.2", optional = true }
 scan_fmt = "0.2.3"
+
+[features]
+with-log = ["slog", "slog-scope"]
+with-agent-handler = ["protobuf", "protocols"]

src/agent/netlink/src/agent_handler.rs

@@ -9,6 +9,7 @@
 use protobuf::RepeatedField;
 use protocols::types::{ARPNeighbor, IPAddress, IPFamily, Interface, Route};
 
+#[cfg(feature = "with-log")]
 // Convenience macro to obtain the scope logger
 macro_rules! sl {
     () => {

src/agent/netlink/src/lib.rs

@@ -9,17 +9,18 @@
 #![allow(unused_parens)]
 #![allow(unused_unsafe)]
 
-mod agent_handler;
-
 extern crate libc;
 extern crate nix;
+
+#[cfg(feature = "with-agent-handler")]
 extern crate protobuf;
+#[cfg(feature = "with-agent-handler")]
 extern crate protocols;
 
+#[cfg(feature = "with-log")]
 #[macro_use]
 extern crate slog;
-extern crate slog_async;
-extern crate slog_json;
+#[cfg(feature = "with-log")]
 extern crate slog_scope;
 
 #[macro_use]
@@ -33,8 +34,7 @@ use std::mem;
 use std::net::{Ipv4Addr, Ipv6Addr};
 use std::str::FromStr;
 
-type Result<T> = std::result::Result<T, nix::Error>;
-
+#[cfg(feature = "with-log")]
 // Convenience macro to obtain the scope logger
 macro_rules! sl {
     () => {
@@ -42,6 +42,19 @@ macro_rules! sl {
     };
 }
 
+#[cfg(not(feature = "with-log"))]
+#[macro_export]
+macro_rules! info {
+    ($l:expr, #$tag:expr, $($args:tt)*) => {};
+    ($l:expr, $($args:tt)*) => {};
+}
+
+#[cfg(feature = "with-agent-handler")]
+mod agent_handler;
+
+/// Specialized version of std::result::Result for Netlink related operations.
+pub type Result<T> = std::result::Result<T, nix::Error>;
+
 // define the struct, const, etc needed by netlink operations
 
 pub type __s8 = libc::c_char;