From 89b5d9294c248f5b178fc81da6b89794c2205e91 Mon Sep 17 00:00:00 2001
From: Lucien Greathouse <me@lpghatguy.com>
Date: Wed, 19 Feb 2020 09:36:38 -0800
Subject: [PATCH] Event receiving/committing infrastructure

---
 vfs/src/lib.rs          | 21 ++++++++++++++++++++-
 vfs/src/noop_backend.rs |  2 +-
 vfs/src/std_backend.rs  |  2 +-
 3 files changed, 22 insertions(+), 3 deletions(-)

diff --git a/vfs/src/lib.rs b/vfs/src/lib.rs
index 19b76a6e..c2f434e4 100644
--- a/vfs/src/lib.rs
+++ b/vfs/src/lib.rs
@@ -26,7 +26,7 @@ pub trait VfsBackend: sealed::Sealed {
     fn read_dir(&mut self, path: &Path) -> io::Result<ReadDir>;
     fn metadata(&mut self, path: &Path) -> io::Result<Metadata>;
 
-    fn event_receiver(&mut self) -> crossbeam_channel::Receiver<VfsEvent>;
+    fn event_receiver(&self) -> crossbeam_channel::Receiver<VfsEvent>;
     fn watch(&mut self, path: &Path) -> io::Result<()>;
     fn unwatch(&mut self, path: &Path) -> io::Result<()>;
 }
@@ -101,6 +101,15 @@ impl VfsLock {
         let path = path.as_ref();
         self.backend.read_dir(path)
     }
+
+    pub fn event_receiver(&self) -> crossbeam_channel::Receiver<VfsEvent> {
+        self.backend.event_receiver()
+    }
+
+    pub fn commit_event(&mut self, _event: &VfsEvent) -> io::Result<()> {
+        // Because we hold no state, there's no cache to update here.
+        Ok(())
+    }
 }
 
 /// A virtual filesystem with a configurable backend.
@@ -156,4 +165,14 @@ impl Vfs {
         let path = path.as_ref();
         self.inner.lock().unwrap().read_dir(path)
     }
+
+    /// Retrieve a handle to the event receiver for this `Vfs`.
+    pub fn event_receiver(&self) -> crossbeam_channel::Receiver<VfsEvent> {
+        self.inner.lock().unwrap().event_receiver()
+    }
+
+    /// Commit an event to this `Vfs`.
+    pub fn commit_event(&self, event: &VfsEvent) -> io::Result<()> {
+        self.inner.lock().unwrap().commit_event(event)
+    }
 }
diff --git a/vfs/src/noop_backend.rs b/vfs/src/noop_backend.rs
index 5d73bd1d..b28103ab 100644
--- a/vfs/src/noop_backend.rs
+++ b/vfs/src/noop_backend.rs
@@ -42,7 +42,7 @@ impl VfsBackend for NoopBackend {
         ))
     }
 
-    fn event_receiver(&mut self) -> crossbeam_channel::Receiver<VfsEvent> {
+    fn event_receiver(&self) -> crossbeam_channel::Receiver<VfsEvent> {
         crossbeam_channel::never()
     }
 
diff --git a/vfs/src/std_backend.rs b/vfs/src/std_backend.rs
index d42d8d6c..d0236c8c 100644
--- a/vfs/src/std_backend.rs
+++ b/vfs/src/std_backend.rs
@@ -82,7 +82,7 @@ impl VfsBackend for StdBackend {
         })
     }
 
-    fn event_receiver(&mut self) -> crossbeam_channel::Receiver<VfsEvent> {
+    fn event_receiver(&self) -> crossbeam_channel::Receiver<VfsEvent> {
         self.watcher_receiver.clone()
     }