feat: Add cargo bench for logging performance

Cargo.toml

@@ -15,3 +15,10 @@ edition = "2018"
 crossbeam-channel = "0.4.4"
 log = { version = "0.4.6", features = ["std"] }
 time = "0.1.35"
+
+[dev-dependencies]
+criterion = "0.3"
+
+[[bench]]
+name = "logging_benchmark"
+harness = false

benches/logging_benchmark.rs

@@ -0,0 +1,54 @@
+use criterion::{black_box, criterion_group, criterion_main, Criterion};
+use fastlog::{LogBuilder}; // Logger is not directly used for initialization here
+use log::{Level, LevelFilter, Record}; // Import Level for Record builder
+use std::path::PathBuf;
+// Timespec is not directly needed in the benchmark file if using default formatter
+// and directly calling logger.log()
+
+fn bench_logging(c: &mut Criterion) {
+    let mut group = c.benchmark_group("logging");
+    let sizes = [10, 100, 1000, 10000];
+
+    for size in sizes.iter() {
+        group.bench_function(format!("log_{}_chars", size), |b| {
+            // Initialize logger for each iteration to ensure flushing and re-creation if necessary,
+            // though for /dev/null it might not matter as much.
+            // However, the logger has a worker thread, re-creating it each time might be too much overhead.
+            // Let's create it once outside b.iter()
+
+            let logger = LogBuilder::new()
+                .file(PathBuf::from(if cfg!(windows) { "NUL" } else { "/dev/null" }))
+                .max_log_level(LevelFilter::Info)
+                .build()
+                .expect("Failed to build logger for benchmarking.");
+
+            let message_to_log = String::from_utf8(vec![b'a'; *size]).unwrap();
+
+            // The Record needs to be created inside b.iter if its content (like timestamp) should vary per iteration,
+            // but for benchmarking the logging of a fixed-size message, creating it once is fine.
+            // However, format_args! captures its arguments by reference.
+            // To be safe and typical for iter, we'll prepare the static parts outside 
+            // and only construct the record with the message inside.
+
+            b.iter(|| {
+                // Construct the record inside the iter block.
+                // The `log` crate's Record builder is suitable here.
+                let record = Record::builder()
+                    .args(format_args!("{}", message_to_log))
+                    .level(Level::Info) // Use Level::Info here
+                    .target("benchmark_target") // Provide a target
+                    .module_path(Some("benchmark_module"))
+                    .file(Some("benches/logging_benchmark.rs"))
+                    .line(Some(line!())) // Use actual line number
+                    .build();
+
+                // Call the log method directly on the logger instance
+                logger.log(black_box(&record));
+            });
+        });
+    }
+    group.finish();
+}
+
+criterion_group!(benches, bench_logging);
+criterion_main!(benches);