snapshot of https://github.com/tauri-apps/tauri.git (dev, 2026-09-23; blobs > 131072B omitted)

crates/tauri/src/state.rs

@@ -0,0 +1,291 @@
+// Copyright 2019-2024 Tauri Programme within The Commons Conservancy
+// SPDX-License-Identifier: Apache-2.0
+// SPDX-License-Identifier: MIT
+
+use std::{
+  any::{Any, TypeId},
+  collections::HashMap,
+  hash::BuildHasherDefault,
+  sync::Mutex,
+};
+
+use crate::{
+  Manager, Runtime,
+  ipc::{CommandArg, CommandItem, InvokeError},
+};
+
+/// A guard for a state value.
+///
+/// See [`Manager::manage`](`crate::Manager::manage`) for usage examples.
+pub struct State<'r, T>(&'r T);
+
+impl<'r, T> State<'r, T> {
+  /// Retrieve a borrow to the underlying value with a lifetime of `'r`.
+  /// Using this method is typically unnecessary as `State` implements
+  /// [`std::ops::Deref`] with a [`std::ops::Deref::Target`] of `T`.
+  #[inline(always)]
+  pub fn inner(&self) -> &'r T {
+    self.0
+  }
+}
+
+impl<T> std::ops::Deref for State<'_, T> {
+  type Target = T;
+
+  #[inline(always)]
+  fn deref(&self) -> &T {
+    self.0
+  }
+}
+
+impl<T> Clone for State<'_, T> {
+  fn clone(&self) -> Self {
+    State(self.0)
+  }
+}
+
+impl<T: PartialEq> PartialEq for State<'_, T> {
+  fn eq(&self, other: &Self) -> bool {
+    self.0 == other.0
+  }
+}
+
+impl<T: std::fmt::Debug> std::fmt::Debug for State<'_, T> {
+  fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+    f.debug_tuple("State").field(&self.0).finish()
+  }
+}
+
+impl<'r, 'de: 'r, T: Send + Sync + 'static, R: Runtime> CommandArg<'de, R> for State<'r, T> {
+  /// Grabs the [`State`] from the [`CommandItem`]. This will never fail.
+  fn from_command(command: CommandItem<'de, R>) -> Result<Self, InvokeError> {
+    command.message.webview_ref().try_state().ok_or_else(|| {
+      InvokeError::from_anyhow(anyhow::anyhow!(
+        "state not managed for field `{}` on command `{}`. You must call `.manage()` before using this command",
+        command.key, command.name
+      ))
+    })
+  }
+}
+
+// Taken from: https://github.com/SergioBenitez/state/blob/556c1b94db8ce8427a0e72de7983ab5a9af4cc41/src/ident_hash.rs
+// This is a _super_ stupid hash. It just uses its input as the hash value. This
+// hash is meant to be used _only_ for "prehashed" values. In particular, we use
+// this so that hashing a TypeId is essentially a noop. This is because TypeIds
+// are already unique integers.
+#[derive(Default)]
+struct IdentHash(u64);
+
+impl std::hash::Hasher for IdentHash {
+  fn finish(&self) -> u64 {
+    self.0
+  }
+
+  fn write(&mut self, bytes: &[u8]) {
+    for byte in bytes {
+      self.write_u8(*byte);
+    }
+  }
+
+  fn write_u8(&mut self, i: u8) {
+    self.0 = (self.0 << 8) | (i as u64);
+  }
+
+  fn write_u64(&mut self, i: u64) {
+    self.0 = i;
+  }
+}
+
+/// Safety:
+/// - The `key` must equal to `(*value).type_id()`, see the safety doc in methods of [StateManager] for details.
+/// - Once you insert a value, you can't remove/mutated/move it anymore, see [StateManager::try_get] for details.
+type TypeIdMap = HashMap<TypeId, Box<dyn Any + Sync + Send>, BuildHasherDefault<IdentHash>>;
+
+/// The Tauri state manager.
+// TODO: make private for v3
+#[derive(Debug)]
+pub struct StateManager {
+  map: Mutex<TypeIdMap>,
+}
+
+impl StateManager {
+  pub(crate) fn new() -> Self {
+    Self {
+      map: Default::default(),
+    }
+  }
+
+  pub(crate) fn set<T: Send + Sync + 'static>(&self, state: T) -> bool {
+    let mut map = self.map.lock().unwrap();
+    let type_id = TypeId::of::<T>();
+    let already_set = map.contains_key(&type_id);
+    if !already_set {
+      let state = Box::new(state) as Box<dyn Any + Sync + Send>;
+      map.insert(type_id, state);
+    }
+    !already_set
+  }
+
+  /// SAFETY: Calling this method will move the `value`,
+  /// which will cause references obtained through [Self::try_get] to dangle.
+  pub(crate) unsafe fn unmanage<T: Send + Sync + 'static>(&self) -> Option<T> {
+    let mut map = self.map.lock().unwrap();
+    let type_id = TypeId::of::<T>();
+    let state = map.remove(&type_id)?;
+    let value = state
+      .downcast::<T>()
+      .expect("the type of the key should be same as the type of the value");
+    Some(*value)
+  }
+
+  /// Gets the state associated with the specified type.
+  pub fn get<T: 'static>(&self) -> State<'_, T> {
+    self
+      .try_get()
+      .unwrap_or_else(|| panic!("state not found for type {}", std::any::type_name::<T>()))
+  }
+
+  /// Gets the state associated with the specified type.
+  pub fn try_get<T: 'static>(&self) -> Option<State<'_, T>> {
+    let map = self.map.lock().unwrap();
+    let type_id = TypeId::of::<T>();
+    let state = map.get(&type_id)?;
+    let value = state
+      .downcast_ref::<T>()
+      .expect("the type of the key should be same as the type of the value");
+    // SAFETY: We ensure the lifetime of `value` is the same as [StateManager] and `value` will not be mutated/moved.
+    let v_ref = unsafe { &*(value as *const T) };
+    Some(State(v_ref))
+  }
+}
+
+// Ported from https://github.com/SergioBenitez/state/blob/556c1b94db8ce8427a0e72de7983ab5a9af4cc41/tests/main.rs
+#[cfg(test)]
+mod tests {
+  use super::StateManager;
+
+  use std::sync::{Arc, RwLock};
+  use std::thread;
+
+  // Tiny structures to test that dropping works as expected.
+  struct DroppingStruct(Arc<RwLock<bool>>);
+  struct DroppingStructWrap(#[allow(dead_code)] DroppingStruct);
+
+  impl Drop for DroppingStruct {
+    fn drop(&mut self) {
+      *self.0.write().unwrap() = true;
+    }
+  }
+
+  #[test]
+  #[should_panic(expected = "state not found for type core::option::Option<alloc::string::String>")]
+  fn get_panics() {
+    let state = StateManager::new();
+    state.get::<Option<String>>();
+  }
+
+  #[test]
+  fn simple_set_get() {
+    let state = StateManager::new();
+    assert!(state.set(1u32));
+    assert_eq!(*state.get::<u32>(), 1);
+  }
+
+  #[test]
+  fn simple_set_get_unmanage() {
+    let state = StateManager::new();
+    assert!(state.set(1u32));
+    assert_eq!(*state.get::<u32>(), 1);
+    // safety: the reference returned by `try_get` is already dropped.
+    assert!(unsafe { state.unmanage::<u32>() }.is_some());
+    assert!(unsafe { state.unmanage::<u32>() }.is_none());
+    assert_eq!(state.try_get::<u32>(), None);
+    assert!(state.set(2u32));
+    assert_eq!(*state.get::<u32>(), 2);
+  }
+
+  #[test]
+  fn dst_set_get() {
+    let state = StateManager::new();
+    assert!(state.set::<[u32; 4]>([1, 2, 3, 4u32]));
+    assert_eq!(*state.get::<[u32; 4]>(), [1, 2, 3, 4]);
+  }
+
+  #[test]
+  fn set_get_remote() {
+    let state = Arc::new(StateManager::new());
+    let sate_ = Arc::clone(&state);
+    thread::spawn(move || {
+      sate_.set(10isize);
+    })
+    .join()
+    .unwrap();
+
+    assert_eq!(*state.get::<isize>(), 10);
+  }
+
+  #[test]
+  fn two_put_get() {
+    let state = StateManager::new();
+    assert!(state.set("Hello, world!".to_string()));
+
+    let s_old = state.get::<String>();
+    assert_eq!(*s_old, "Hello, world!");
+
+    assert!(!state.set::<String>("Bye bye!".into()));
+    assert_eq!(*state.get::<String>(), "Hello, world!");
+    assert_eq!(state.get::<String>(), s_old);
+  }
+
+  #[test]
+  fn many_puts_only_one_succeeds() {
+    let state = Arc::new(StateManager::new());
+    let mut threads = vec![];
+    for _ in 0..1000 {
+      let state_ = Arc::clone(&state);
+      threads.push(thread::spawn(move || state_.set(10i64)))
+    }
+
+    let results: Vec<bool> = threads.into_iter().map(|t| t.join().unwrap()).collect();
+    assert_eq!(results.into_iter().filter(|&b| b).count(), 1);
+    assert_eq!(*state.get::<i64>(), 10);
+  }
+
+  // Ensure setting when already set doesn't cause a drop.
+  #[test]
+  fn test_no_drop_on_set() {
+    let state = StateManager::new();
+    let drop_flag = Arc::new(RwLock::new(false));
+    let dropping_struct = DroppingStruct(drop_flag.clone());
+
+    let _drop_flag_ignore = Arc::new(RwLock::new(false));
+    let _dropping_struct_ignore = DroppingStruct(_drop_flag_ignore);
+
+    state.set::<DroppingStruct>(dropping_struct);
+    assert!(!state.set::<DroppingStruct>(_dropping_struct_ignore));
+    assert!(!*drop_flag.read().unwrap());
+  }
+
+  // Ensure dropping a type_map drops its contents.
+  #[test]
+  fn drop_inners_on_drop() {
+    let drop_flag_a = Arc::new(RwLock::new(false));
+    let dropping_struct_a = DroppingStruct(drop_flag_a.clone());
+
+    let drop_flag_b = Arc::new(RwLock::new(false));
+    let dropping_struct_b = DroppingStructWrap(DroppingStruct(drop_flag_b.clone()));
+
+    {
+      let state = StateManager::new();
+      state.set(dropping_struct_a);
+      assert!(!*drop_flag_a.read().unwrap());
+
+      state.set(dropping_struct_b);
+      assert!(!*drop_flag_a.read().unwrap());
+      assert!(!*drop_flag_b.read().unwrap());
+    }
+
+    assert!(*drop_flag_a.read().unwrap());
+    assert!(*drop_flag_b.read().unwrap());
+  }
+}