Add new fn helpers::create_if_not_exist

Signed-off-by: Jiahao XU <Jiahao_XU@outlook.com>

src/helpers.rs

@@ -53,6 +53,30 @@ pub fn cargo_home() -> Result<&'static Path, io::Error> {
         .map(ops::Deref::deref)
 }
 
+pub fn create_if_not_exist(path: impl AsRef<Path>) -> io::Result<fs::File> {
+    let mut options = fs::File::options();
+    options.create_new(true);
+
+    for _ in 0..3 {
+        match options.open(path.as_ref()) {
+            Ok(file) => return Ok(file),
+            Err(io_err) if io_err.kind() == io::ErrorKind::AlreadyExists => {
+                match fs::File::open(path.as_ref()) {
+                    Ok(file) => return Ok(file),
+                    Err(io_err) if io_err.kind() == io::ErrorKind::NotFound => (),
+                    Err(err) => return Err(err),
+                }
+            }
+            Err(err) => return Err(err),
+        }
+    }
+
+    let errmsg = "We tried to open this file three times but all attempts have failed
+        with creation returns AlreadyExists and opening returns NotFound";
+
+    Err(io::Error::new(io::ErrorKind::TimedOut, errmsg))
+}
+
 pub async fn await_task<T>(task: tokio::task::JoinHandle<miette::Result<T>>) -> miette::Result<T> {
     match task.await {
         Ok(res) => res,