hide latency mod behind feature gate

Cargo.toml

@@ -35,7 +35,7 @@ decimal = { path = "../decimal", version = "2" }
 
 #windows = { path = "../windows", version = "0.2" }
 money = { path = "../money", version = "0.3" }
-pubsub = { path = "../pubsub" }
+pubsub = { path = "../pubsub", optional = true }
 
 [features]
 default = ["inlines"]
@@ -51,3 +51,4 @@ no-influx-buffer = []
 disable-short-uuid = []
 warnings = []
 inlines = []
+latency = ["pubsub"]

src/lib.rs

@@ -26,7 +26,7 @@ extern crate num;
 extern crate dirs;
 #[cfg(feature = "zmq")]
 extern crate zmq;
-
+#[cfg(feature = "latency")]
 extern crate pubsub as pub_sub;
 
 use chrono::{DateTime, Utc, TimeZone as ChronoTZ};
@@ -43,6 +43,7 @@ use uuid::Uuid;
 pub mod influx;
 #[cfg(feature = "warnings")]
 pub mod warnings;
+#[cfg(feature = "latency")]
 pub mod latency;
 pub mod hist;