Level-based logging for graphql schema tools

Summary: Replacing `println!` with level-based logging. Main goal was to get timestamp-ed messages but it also keeps code clean from `if (verbose) { ... }` kind of blocks.

Reviewed By: gary-z

Differential Revision: D47189630

fbshipit-source-id: 18cad398ac6bd65acc2448b553f1a2b49152030a

compiler/crates/schema-validate/Cargo.toml

@@ -20,6 +20,7 @@ common = { path = "../common" }
 fnv = "1.0"
 intern = { path = "../intern" }
 lazy_static = "1.4"
+log = { version = "0.4.17", features = ["kv_unstable", "kv_unstable_std"] }
 rayon = "1.2"
 regex = "1.6.0"
 schema = { path = "../schema" }

compiler/crates/schema-validate/src/lib.rs

@@ -21,6 +21,7 @@ use intern::string_key::Intern;
 use intern::string_key::StringKey;
 use intern::Lookup;
 use lazy_static::lazy_static;
+use log::info;
 use rayon::prelude::*;
 use regex::Regex;
 use schema::EnumID;
@@ -97,8 +98,8 @@ impl<'schema> ValidationContext<'schema> {
         self.validate_root_types();
         self.validate_directives();
         self.validate_types();
-        println!("Validated Schema in {}ms", now.elapsed().as_millis());
-        println!(
+        info!("Validated Schema in {}ms", now.elapsed().as_millis());
+        info!(
             "Found {} validation errors",
             self.errors.lock().unwrap().len()
         )