Validator log filter may now be reconfigured at runtime (#5473)

* Log filter may now be reconfigured at runtime

* Add RPC API and bash script to reconfigure the log filter

Cargo.lock

@@ -3505,6 +3505,8 @@ name = "solana-logger"
 version = "0.18.0-pre1"
 dependencies = [
  "env_logger 0.6.2 (registry+https://github.com/rust-lang/crates.io-index)",
+ "lazy_static 1.3.0 (registry+https://github.com/rust-lang/crates.io-index)",
+ "log 0.4.8 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
 
 [[package]]

core/src/rpc.rs

@@ -328,6 +328,9 @@ pub trait RpcSol {
 
     #[rpc(meta, name = "getVersion")]
     fn get_version(&self, _: Self::Metadata) -> Result<RpcVersionInfo>;
+
+    #[rpc(meta, name = "setLogFilter")]
+    fn set_log_filter(&self, _: Self::Metadata, _: String) -> Result<()>;
 }
 
 pub struct RpcSolImpl;
@@ -619,6 +622,11 @@ impl RpcSol for RpcSolImpl {
             solana_core: VERSION.to_string(),
         })
     }
+
+    fn set_log_filter(&self, _: Self::Metadata, filter: String) -> Result<()> {
+        solana_logger::setup_with_filter(&filter);
+        Ok(())
+    }
 }
 
 #[cfg(test)]

logger/Cargo.toml

@@ -10,6 +10,8 @@ edition = "2018"
 
 [dependencies]
 env_logger = "0.6.2"
+lazy_static = "1.3.0"
+log = "0.4.8"
 
 [lib]
 name = "solana_logger"

logger/src/lib.rs

@@ -1,19 +1,41 @@
-//! The `logger` module provides a setup function for `env_logger`. Its only function,
-//! `setup()` may be called multiple times.
+//! The `logger` module configures `env_logger`
 
-use env_logger;
-use std::sync::Once;
+use lazy_static::lazy_static;
+use std::sync::{Arc, RwLock};
 
-static INIT: Once = Once::new();
-
-pub fn setup_with_filter(filter: &str) {
-    INIT.call_once(|| {
-        env_logger::Builder::from_env(env_logger::Env::new().default_filter_or(filter))
-            .default_format_timestamp_nanos(true)
-            .init();
-    });
+lazy_static! {
+    static ref LOGGER: Arc<RwLock<env_logger::Logger>> =
+        { Arc::new(RwLock::new(env_logger::Logger::from_default_env())) };
 }
 
+struct LoggerShim {}
+
+impl log::Log for LoggerShim {
+    fn enabled(&self, metadata: &log::Metadata) -> bool {
+        LOGGER.read().unwrap().enabled(metadata)
+    }
+
+    fn log(&self, record: &log::Record) {
+        LOGGER.read().unwrap().log(record);
+    }
+
+    fn flush(&self) {}
+}
+
+// Configures logging with a specific filter.
+// May be called at any time to re-configure the log filter
+pub fn setup_with_filter(filter: &str) {
+    let logger = env_logger::Builder::from_env(env_logger::Env::new().default_filter_or(filter))
+        .default_format_timestamp_nanos(true)
+        .build();
+    let max_level = logger.filter();
+    log::set_max_level(max_level);
+    let mut rw = LOGGER.write().unwrap();
+    std::mem::replace(&mut *rw, logger);
+    let _ = log::set_boxed_logger(Box::new(LoggerShim {}));
+}
+
+// Configures logging with the default filter ("error")
 pub fn setup() {
     setup_with_filter("error");
 }

scripts/set-log-filter.sh

@@ -0,0 +1,27 @@
+#!/usr/bin/env bash
+#
+# Reconfigures the log filter on a validator using the current RUST_LOG value
+#
+
+if [[ -n $1 ]]; then
+  url=$1
+else
+  # Default to the local node
+  url=http://127.0.0.1:8899
+fi
+
+if [[ -z $RUST_LOG ]]; then
+  echo "RUST_LOG not defined"
+  exit 1
+fi
+
+set -x
+exec curl $url -X POST -H "Content-Type: application/json" \
+  -d "
+    {
+      \"jsonrpc\": \"2.0\",
+      \"id\": 1,
+      \"method\": \"setLogFilter\",
+      \"params\": [\"$RUST_LOG\"]
+    }
+  "