Refactor API to use a Guard internally

Signed-off-by: Matthias Beyer <matthias.beyer@ifm.com>

5 files changed, 62 insertions, 48 deletions

diff --git a/plugins/plugin_fdman/src/file.rs b/plugins/plugin_fdman/src/file.rs
new file mode 100644
index 00000000..012e35a3
--- /dev/null
+++ b/plugins/plugin_fdman/src/file.rs
@@ -0,0 +1,27 @@
+use crate::guard::Guard;
+
+#[derive(Debug)]
+pub struct FileGuard {
+    file: std::fs::File,
+    guard: Guard,
+}
+
+impl FileGuard {
+    pub(crate) fn new(file: std::fs::File, guard: Guard) -> Self {
+        Self { file, guard }
+    }
+}
+
+impl std::ops::Deref for FileGuard {
+    type Target = std::fs::File;
+
+    fn deref(&self) -> &Self::Target {
+        &self.file
+    }
+}
+
+impl std::ops::DerefMut for FileGuard {
+    fn deref_mut(&mut self) -> &mut Self::Target {
+        &mut self.file
+    }
+}
diff --git a/plugins/plugin_fdman/src/guard.rs b/plugins/plugin_fdman/src/guard.rs
new file mode 100644
index 00000000..a464ef32
--- /dev/null
+++ b/plugins/plugin_fdman/src/guard.rs
@@ -0,0 +1,20 @@
+use std::sync::{atomic::AtomicU64, Arc};
+
+#[derive(Debug)]
+pub struct Guard {
+    tokens: u64,
+    handle_ref: Arc<AtomicU64>,
+}
+
+impl Guard {
+    pub fn new(tokens: u64, handle_ref: Arc<AtomicU64>) -> Self {
+        Self { tokens, handle_ref }
+    }
+}
+
+impl Drop for Guard {
+    fn drop(&mut self) {
+        self.handle_ref
+            .fetch_sub(self.tokens, std::sync::atomic::Ordering::SeqCst);
+    }
+}
diff --git a/plugins/plugin_fdman/src/lib.rs b/plugins/plugin_fdman/src/lib.rs
index 71e12f2a..e7526604 100644
--- a/plugins/plugin_fdman/src/lib.rs
+++ b/plugins/plugin_fdman/src/lib.rs
@@ -1,9 +1,12 @@
 mod builder;
 mod config;
 mod error;
-pub mod message;
+mod guard;
 mod plugin;
 
+pub mod file;
+pub mod message;
+
 pub use crate::builder::FdManPluginBuilder;
 pub use crate::error::Error;
 pub use crate::plugin::FdManPlugin;
diff --git a/plugins/plugin_fdman/src/message/open_options.rs b/plugins/plugin_fdman/src/message/open_options.rs
index c8913052..39cc926e 100644
--- a/plugins/plugin_fdman/src/message/open_options.rs
+++ b/plugins/plugin_fdman/src/message/open_options.rs
@@ -1,10 +1,9 @@
-use std::{
-    path::PathBuf,
-    sync::{atomic::AtomicU64, Arc},
-};
+use std::path::PathBuf;
 
 use tedge_api::Message;
 
+use crate::file::FileGuard;
+
 #[derive(Clone, Debug, bevy_reflect::TypeUuid)]
 #[uuid = "cf82a6ed-3fc1-4011-bbf0-c79fc6fdf781"]
 pub struct OpenOptions {
@@ -81,42 +80,6 @@ impl tedge_api::message::AcceptsReplies for OpenOptions {
     type Reply = OpenOptionsResult;
 }
 
-#[derive(Debug)]
-pub struct OpenOptionsFile {
-    file: std::fs::File,
-    currently_held_count: Arc<AtomicU64>,
-}
-
-impl OpenOptionsFile {
-    pub(crate) fn new(file: std::fs::File, currently_held_count: Arc<AtomicU64>) -> Self {
-        Self {
-            file,
-            currently_held_count,
-        }
-    }
-}
-
-impl Drop for OpenOptionsFile {
-    fn drop(&mut self) {
-        self.currently_held_count
-            .fetch_sub(1, std::sync::atomic::Ordering::SeqCst);
-    }
-}
-
-impl std::ops::Deref for OpenOptionsFile {
-    type Target = std::fs::File;
-
-    fn deref(&self) -> &Self::Target {
-        &self.file
-    }
-}
-
-impl std::ops::DerefMut for OpenOptionsFile {
-    fn deref_mut(&mut self) -> &mut Self::Target {
-        &mut self.file
-    }
-}
-
 #[derive(Debug, thiserror::Error)]
 pub enum OpenOptionsError {
     #[error("FdMan Plugin error")]
@@ -127,13 +90,13 @@ pub enum OpenOptionsError {
 #[uuid = "e259bed9-14b9-4edf-ab7b-e87d454b823f"]
 pub struct OpenOptionsResult {
     open_options: OpenOptions,
-    result: Result<OpenOptionsFile, OpenOptionsError>,
+    result: Result<FileGuard, OpenOptionsError>,
 }
 
 impl OpenOptionsResult {
     pub(crate) fn new(
         open_options: OpenOptions,
-        result: Result<OpenOptionsFile, OpenOptionsError>,
+        result: Result<FileGuard, OpenOptionsError>,
     ) -> Self {
         Self {
             open_options,
@@ -145,11 +108,11 @@ impl OpenOptionsResult {
         &self.open_options
     }
 
-    pub fn result(&self) -> &Result<OpenOptionsFile, OpenOptionsError> {
+    pub fn result(&self) -> &Result<FileGuard, OpenOptionsError> {
         &self.result
     }
 
-    pub fn into_result(self) -> Result<OpenOptionsFile, OpenOptionsError> {
+    pub fn into_result(self) -> Result<FileGuard, OpenOptionsError> {
         self.result
     }
 }
diff --git a/plugins/plugin_fdman/src/plugin.rs b/plugins/plugin_fdman/src/plugin.rs
index de36855c..0c959162 100644
--- a/plugins/plugin_fdman/src/plugin.rs
+++ b/plugins/plugin_fdman/src/plugin.rs
@@ -9,6 +9,7 @@ use tedge_api::{
 
 use crate::{
     error::Error,
+    guard::Guard,
     message::{OpenOptions, OpenOptionsError, OpenOptionsResult},
 };
 
@@ -74,16 +75,16 @@ impl Handle<OpenOptions> for FdManPlugin {
                             Err(OpenOptionsError::from(err)),
                         ))
                         .map_err(|_| Error::SendingReply)
-                        .map_err(PluginError::from)
+                        .map_err(PluginError::from);
                 }
 
                 let file_result = message
                     .as_std()
                     .open(message.path())
                     .map(|file| {
-                        crate::message::OpenOptionsFile::new(
+                        crate::file::FileGuard::new(
                             file,
-                            self.currently_held_count.clone(),
+                            Guard::new(aquired_handles, self.currently_held_count.clone()),
                         )
                     })
                     .map_err(Error::from)