# jfrs
[](https://github.com/ocadaruma/jfrs/actions/workflows/ci.yml)
[](https://crates.io/crates/jfrs)
Java Flight Recorder reader for Rust
## Features
### Read events (low-level API)
```rust
fn main() {
let mut reader = JfrReader::new(File::open("/path/to/recording.jfr").unwrap());
for (reader, chunk) in reader.chunks().flatten() {
for event in reader.events(&chunk)
.flatten()
.filter(|e| e.class.name() == "jdk.ExecutionSample")
{
let thread_name = event.value()
.get_field("sampledThread")
.and_then(|v| v.get_field("osName"))
.and_then(|v| <&str>::try_from(v.value).ok())
.unwrap();
println!("sampled thread: {}", thread_name);
}
}
}
```
### \[Experimental\] Deserialize events as Rust struct
> **Note**
> As of now, deserialization performance is very poor. See [tuning_notes.md](./example/tuning_notes.md) for the details.
Though low-level API provides full functionality to interpret the events as you need,
usually we want to map known JFR events to the Rust structure.
`jfrs` also provides `serde-rs` based deserialization feature.
```rust
fn main() {
let mut reader = JfrReader::new(File::open("/path/to/recording.jfr").unwrap());
for (reader, chunk) in reader.chunks().flatten() {
for event in reader.events(&chunk)
.flatten()
.filter(|e| e.class.name() == "jdk.ExecutionSample")
{
let sample: ExecutionSample = from_event(&event).unwrap();
println!("sampled thread: {}", sample.sampled_thread.and_then(|t| t.os_name).unwrap());
}
}
}
```