6 files changed, 72 insertions, 27 deletions

diff --git a/crates/ra_db/src/cancellation.rs b/crates/ra_db/src/cancellation.rs
index 8d38eebfb..32a268553 100644
--- a/crates/ra_db/src/cancellation.rs
+++ b/crates/ra_db/src/cancellation.rs
@@ -27,6 +27,12 @@ impl Canceled {
     pub(crate) fn new() -> Canceled {
         Canceled { _private: () }
     }
+
+    pub fn throw() -> ! {
+        // We use resume and not panic here to avoid running the panic
+        // hook (that is, to avoid collecting and printing backtrace).
+        std::panic::resume_unwind(Box::new(Canceled::new()))
+    }
 }
 
 impl std::fmt::Display for Canceled {
diff --git a/crates/ra_db/src/lib.rs b/crates/ra_db/src/lib.rs
index fb8ea2496..20e712afe 100644
--- a/crates/ra_db/src/lib.rs
+++ b/crates/ra_db/src/lib.rs
@@ -5,6 +5,8 @@ mod input;
 mod loc2id;
 pub mod mock;
 
+use std::panic;
+
 use ra_syntax::{TextUnit, TextRange, SourceFile, TreePtr};
 
 pub use crate::{
@@ -18,13 +20,21 @@ pub use crate::{
     loc2id::LocationIntener,
 };
 
-pub trait BaseDatabase: salsa::Database {
+pub trait BaseDatabase: salsa::Database + panic::RefUnwindSafe {
     fn check_canceled(&self) -> Cancelable<()> {
-        if self.salsa_runtime().is_current_revision_canceled() {
-            Err(Canceled::new())
-        } else {
-            Ok(())
-        }
+        self.salsa_runtime()
+            .if_current_revision_is_canceled(Canceled::throw);
+        Ok(())
+    }
+
+    fn catch_canceled<F: FnOnce(&Self) -> T + panic::UnwindSafe, T>(
+        &self,
+        f: F,
+    ) -> Result<T, Canceled> {
+        panic::catch_unwind(|| f(self)).map_err(|err| match err.downcast::<Canceled>() {
+            Ok(canceled) => *canceled,
+            Err(payload) => panic::resume_unwind(payload),
+        })
     }
 }
 
diff --git a/crates/ra_db/src/loc2id.rs b/crates/ra_db/src/loc2id.rs
index 254c52629..359cd893d 100644
--- a/crates/ra_db/src/loc2id.rs
+++ b/crates/ra_db/src/loc2id.rs
@@ -1,4 +1,4 @@
-use std::hash::Hash;
+use std::{panic, hash::Hash};
 
 use parking_lot::Mutex;
 use rustc_hash::FxHashMap;
@@ -70,6 +70,15 @@ where
     map: Mutex<Loc2IdMap<LOC, ID>>,
 }
 
+impl<LOC, ID> panic::RefUnwindSafe for LocationIntener<LOC, ID>
+where
+    ID: ArenaId + Clone,
+    LOC: Clone + Eq + Hash,
+    ID: panic::RefUnwindSafe,
+    LOC: panic::RefUnwindSafe,
+{
+}
+
 impl<LOC, ID> Default for LocationIntener<LOC, ID>
 where
     ID: ArenaId + Clone,
diff --git a/crates/ra_hir/src/mock.rs b/crates/ra_hir/src/mock.rs
index 0fae7de82..7a0301648 100644
--- a/crates/ra_hir/src/mock.rs
+++ b/crates/ra_hir/src/mock.rs
@@ -1,4 +1,4 @@
-use std::sync::Arc;
+use std::{sync::Arc, panic};
 
 use parking_lot::Mutex;
 use salsa::{self, Database};
@@ -18,6 +18,8 @@ pub(crate) struct MockDatabase {
     file_counter: u32,
 }
 
+impl panic::RefUnwindSafe for MockDatabase {}
+
 impl MockDatabase {
     pub(crate) fn with_files(fixture: &str) -> (MockDatabase, SourceRoot) {
         let (db, source_root, position) = MockDatabase::from_fixture(fixture);
diff --git a/crates/ra_ide_api/src/db.rs b/crates/ra_ide_api/src/db.rs
index 9d46609ec..a2e06f5db 100644
--- a/crates/ra_ide_api/src/db.rs
+++ b/crates/ra_ide_api/src/db.rs
@@ -1,7 +1,7 @@
 use std::{fmt, sync::Arc};
 
 use salsa::{self, Database};
-use ra_db::{LocationIntener, BaseDatabase, FileId};
+use ra_db::{LocationIntener, BaseDatabase, FileId, Canceled};
 
 use crate::{symbol_index, LineIndex};
 
@@ -29,6 +29,9 @@ impl salsa::Database for RootDatabase {
     fn salsa_runtime(&self) -> &salsa::Runtime<RootDatabase> {
         &self.runtime
     }
+    fn on_propagated_panic(&self) -> ! {
+        Canceled::throw()
+    }
 }
 
 impl Default for RootDatabase {
diff --git a/crates/ra_ide_api/src/lib.rs b/crates/ra_ide_api/src/lib.rs
index fbe1421a4..f505959ce 100644
--- a/crates/ra_ide_api/src/lib.rs
+++ b/crates/ra_ide_api/src/lib.rs
@@ -35,7 +35,7 @@ use std::{fmt, sync::Arc};
 
 use ra_syntax::{SmolStr, SourceFile, TreePtr, SyntaxKind, TextRange, TextUnit};
 use ra_text_edit::TextEdit;
-use ra_db::{SyntaxDatabase, FilesDatabase, LocalSyntaxPtr};
+use ra_db::{SyntaxDatabase, FilesDatabase, LocalSyntaxPtr, BaseDatabase};
 use rayon::prelude::*;
 use relative_path::RelativePathBuf;
 use rustc_hash::FxHashMap;
@@ -420,43 +420,47 @@ impl Analysis {
 
     /// Fuzzy searches for a symbol.
     pub fn symbol_search(&self, query: Query) -> Cancelable<Vec<NavigationTarget>> {
-        let res = symbol_index::world_symbols(&*self.db, query)?
-            .into_iter()
-            .map(NavigationTarget::from_symbol)
-            .collect();
-        Ok(res)
+        self.with_db(|db| {
+            let res = symbol_index::world_symbols(db, query)?
+                .into_iter()
+                .map(NavigationTarget::from_symbol)
+                .collect::<Vec<_>>();
+            Ok(res)
+        })?
     }
 
     pub fn goto_definition(
         &self,
         position: FilePosition,
     ) -> Cancelable<Option<Vec<NavigationTarget>>> {
-        goto_definition::goto_definition(&*self.db, position)
+        self.db
+            .catch_canceled(|db| goto_definition::goto_definition(db, position))?
     }
 
     /// Finds all usages of the reference at point.
     pub fn find_all_refs(&self, position: FilePosition) -> Cancelable<Vec<(FileId, TextRange)>> {
-        self.db.find_all_refs(position)
+        self.with_db(|db| db.find_all_refs(position))?
     }
 
     /// Returns a short text descrbing element at position.
     pub fn hover(&self, position: FilePosition) -> Cancelable<Option<RangeInfo<String>>> {
-        hover::hover(&*self.db, position)
+        self.with_db(|db| hover::hover(db, position))?
     }
 
     /// Computes parameter information for the given call expression.
     pub fn call_info(&self, position: FilePosition) -> Cancelable<Option<CallInfo>> {
-        call_info::call_info(&*self.db, position)
+        self.db
+            .catch_canceled(|db| call_info::call_info(db, position))?
     }
 
     /// Returns a `mod name;` declaration which created the current module.
     pub fn parent_module(&self, position: FilePosition) -> Cancelable<Vec<NavigationTarget>> {
-        self.db.parent_module(position)
+        self.with_db(|db| db.parent_module(position))?
     }
 
     /// Returns crates this file belongs too.
     pub fn crate_for(&self, file_id: FileId) -> Cancelable<Vec<CrateId>> {
-        self.db.crate_for(file_id)
+        self.with_db(|db| db.crate_for(file_id))?
     }
 
     /// Returns the root file of the given crate.
@@ -466,17 +470,21 @@ impl Analysis {
 
     /// Returns the set of possible targets to run for the current file.
     pub fn runnables(&self, file_id: FileId) -> Cancelable<Vec<Runnable>> {
-        runnables::runnables(&*self.db, file_id)
+        self.db
+            .catch_canceled(|db| runnables::runnables(db, file_id))?
     }
 
     /// Computes syntax highlighting for the given file.
     pub fn highlight(&self, file_id: FileId) -> Cancelable<Vec<HighlightedRange>> {
-        syntax_highlighting::highlight(&*self.db, file_id)
+        self.db
+            .catch_canceled(|db| syntax_highlighting::highlight(db, file_id))?
     }
 
     /// Computes completions at the given position.
     pub fn completions(&self, position: FilePosition) -> Cancelable<Option<Vec<CompletionItem>>> {
-        let completions = completion::completions(&self.db, position)?;
+        let completions = self
+            .db
+            .catch_canceled(|db| completion::completions(db, position))??;
         Ok(completions.map(|it| it.into()))
     }
 
@@ -488,12 +496,12 @@ impl Analysis {
 
     /// Computes the set of diagnostics for the given file.
     pub fn diagnostics(&self, file_id: FileId) -> Cancelable<Vec<Diagnostic>> {
-        self.db.diagnostics(file_id)
+        self.with_db(|db| db.diagnostics(file_id))?
     }
 
     /// Computes the type of the expression at the given position.
     pub fn type_of(&self, frange: FileRange) -> Cancelable<Option<String>> {
-        hover::type_of(&*self.db, frange)
+        self.with_db(|db| hover::type_of(db, frange))?
     }
 
     /// Returns the edit required to rename reference at the position to the new
@@ -503,7 +511,14 @@ impl Analysis {
         position: FilePosition,
         new_name: &str,
     ) -> Cancelable<Vec<SourceFileEdit>> {
-        self.db.rename(position, new_name)
+        self.with_db(|db| db.rename(position, new_name))?
+    }
+
+    fn with_db<F: FnOnce(&db::RootDatabase) -> T + std::panic::UnwindSafe, T>(
+        &self,
+        f: F,
+    ) -> Cancelable<T> {
+        self.db.catch_canceled(f)
     }
 }