add dir parameter to crox

if dir is added all events files will be located in that dir
and then all event will be merged to one chrome_profiler.json file

CHANGELOG.md

@@ -3,6 +3,8 @@
 ## Unreleased
 ### Added
 - `flamegraph`: new tool that uses the `inferno` crate to generate flamegraph svg files ([GH-73])
+- `crox`: Added the `--dir` parameter to merge all events files in dir in to one trace file ([GH-84])
+- `crox`: Added possibility to add multiple `file_prefix` parameters to merge all them to one trace file ([GH-84])
 
 ### Changed
 - `measureme`: Events are recorded in a more compact format ([GH-76])
@@ -47,3 +49,4 @@
 [GH-70]: https://github.com/rust-lang/measureme/pull/70
 [GH-73]: https://github.com/rust-lang/measureme/pull/73
 [GH-76]: https://github.com/rust-lang/measureme/pull/76
+[GH-84]: https://github.com/rust-lang/measureme/pull/84

crox/src/main.rs

@@ -44,7 +44,11 @@ struct Event {
 
 #[derive(StructOpt, Debug)]
 struct Opt {
+    #[structopt(required_unless = "dir")]
     file_prefix: Vec<PathBuf>,
+    /// all event trace files in dir will be merged to one chrome_profiler.json file
+    #[structopt(long = "dir")]
+    dir: Option<PathBuf>,
     /// collapse threads without overlapping events
     #[structopt(long = "collapse-threads")]
     collapse_threads: bool,
@@ -120,7 +124,9 @@ fn main() -> Result<(), Box<dyn std::error::Error>> {
 
     let mut seq = serializer.serialize_seq(None)?;
 
-    for file_prefix in opt.file_prefix.iter() {
+    let dir_paths = file_prefixes_in_dir(&opt)?;
+
+    for file_prefix in opt.file_prefix.iter().chain(dir_paths.iter()) {
         let data = ProfilingData::new(&file_prefix)?;
 
         let thread_to_collapsed_thread = generate_thread_to_collapsed_thread_mapping(&opt, &data);
@@ -191,6 +197,20 @@ fn main() -> Result<(), Box<dyn std::error::Error>> {
     Ok(())
 }
 
+fn file_prefixes_in_dir(opt: &Opt) -> Result<Vec<PathBuf>, std::io::Error> {
+    let mut result = Vec::new();
+    if let Some(dir_path) = &opt.dir {
+        for entry in fs::read_dir(dir_path)? {
+            let entry = entry?;
+            let path = entry.path();
+            if path.extension().filter(|e| *e == "events").is_some() {
+                result.push(path)
+            }
+        }
+    }
+    Ok(result)
+}
+
 fn timestamp_to_min_max(timestamp: Timestamp) -> (SystemTime, SystemTime) {
     match timestamp {
         Timestamp::Instant(t) => (t, t),