[yew-devel] [PATCH yew-widget-toolkit v2 0/2] improve error message on store locks and add non-panicking functions

[yew-devel] [PATCH yew-widget-toolkit v2 0/2] improve error message on store locks and add non-panicking functions

[Shannon Sterz]

this series adds more context to a locking failure in the first commit.
the second commit then adds functions that allow components to recover
from not being able to acquire a lock, instead of simply panicking.

--

changes since v1 (thanks @ Dominik):

- rephrase the commit message of the first commit

changes since rfc:

- don't use `UnwrapThrowExt` as it does not improve error handling
  meaningfully. (thanks @ Dominik)
- add `try_read()` and `try_write()` functions to allow components to
  recover from not being able to acquire a lock instead of panicking.

--

Shannon Sterz (2):
  store: use try_borrow and expect for better error messages
  store: add try_read() and try_write() functions

 src/state/store.rs | 32 +++++++++++++++++++++++++-------
 1 file changed, 25 insertions(+), 7 deletions(-)

--
2.39.5



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[yew-devel] [PATCH yew-widget-toolkit v2 1/2] store: use try_borrow and expect for better error messages

[Shannon Sterz]

this commit adds more context for panics based on failed locks. this
is done by using `try_borrow()` and calling `expect()` on the result.

Signed-off-by: Shannon Sterz <s.sterz@proxmox.com>
---
 src/state/store.rs | 11 +++++++++--
 1 file changed, 9 insertions(+), 2 deletions(-)

diff --git a/src/state/store.rs b/src/state/store.rs
index bde7d9da..67e72b77 100644
--- a/src/state/store.rs
+++ b/src/state/store.rs
@@ -130,7 +130,10 @@ impl<T: 'static> Store<T> {
     /// Panics if the value is currently mutably locked.
     pub fn read(&self) -> StoreReadGuard<T> {
         StoreReadGuard {
-            state: self.inner.borrow(),
+            state: self
+                .inner
+                .try_borrow()
+                .expect("Could not acquire read lock on store!"),
         }
     }
 
@@ -142,7 +145,11 @@ impl<T: 'static> Store<T> {
     /// When the returned [StoreWriteGuard] is dropped, the store listeners
     /// are notified. To prevent that use [StoreWriteGuard::skip_update]
     pub fn write(&self) -> StoreWriteGuard<T> {
-        let state = self.inner.borrow_mut();
+        let state = self
+            .inner
+            .try_borrow_mut()
+            .expect("Could not acquire write lock on store!");
+
         StoreWriteGuard {
             state,
             update: true,
-- 
2.39.5



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[yew-devel] [PATCH yew-widget-toolkit v2 2/2] store: add try_read() and try_write() functions

[Shannon Sterz]

these let users of the store decide whether failure to acquire a lock
on a store is critical enough to panic or whether this scenario can be
handled just fine.

Signed-off-by: Shannon Sterz <s.sterz@proxmox.com>
---
 src/state/store.rs | 37 ++++++++++++++++++++++++-------------
 1 file changed, 24 insertions(+), 13 deletions(-)

diff --git a/src/state/store.rs b/src/state/store.rs
index 67e72b77..42cb53b3 100644
--- a/src/state/store.rs
+++ b/src/state/store.rs
@@ -3,6 +3,7 @@ use std::ops::Range;
 use std::ops::{Deref, DerefMut};
 use std::rc::Rc;
 
+use anyhow::Error;
 use derivative::Derivative;
 use slab::Slab;
 
@@ -129,12 +130,18 @@ impl<T: 'static> Store<T> {
     ///
     /// Panics if the value is currently mutably locked.
     pub fn read(&self) -> StoreReadGuard<T> {
-        StoreReadGuard {
-            state: self
-                .inner
-                .try_borrow()
-                .expect("Could not acquire read lock on store!"),
-        }
+        self.try_read()
+            .expect("Could not acquire read lock on store!")
+    }
+
+    /// Try to lock this store for read access.
+    ///
+    /// Will return an error if the lock could not be acquired due to a write lock still being in
+    /// place.
+    pub fn try_read(&self) -> Result<StoreReadGuard<T>, Error> {
+        Ok(StoreReadGuard {
+            state: self.inner.try_borrow()?,
+        })
     }
 
     /// Lock this store for write access.
@@ -145,15 +152,19 @@ impl<T: 'static> Store<T> {
     /// When the returned [StoreWriteGuard] is dropped, the store listeners
     /// are notified. To prevent that use [StoreWriteGuard::skip_update]
     pub fn write(&self) -> StoreWriteGuard<T> {
-        let state = self
-            .inner
-            .try_borrow_mut()
-            .expect("Could not acquire write lock on store!");
+        self.try_write()
+            .expect("Could not acquire write lock on store!")
+    }
 
-        StoreWriteGuard {
-            state,
+    /// Try to lock this store for write access.
+    ///
+    /// Will return an error if the lock could not be acquired due to a read or write lock still
+    /// being in place.
+    pub fn try_write(&self) -> Result<StoreWriteGuard<T>, Error> {
+        Ok(StoreWriteGuard {
+            state: self.inner.try_borrow_mut()?,
             update: true,
-        }
+        })
     }
 
     // DataStore trait implementation, so that we can use those
-- 
2.39.5



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[yew-devel] applied: [PATCH yew-widget-toolkit v2 0/2] improve error message on store locks and add non-panicking functions

[Dietmar Maurer]

applied


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