ref: Make SourceBundleDebugSession: Send, Sync and AsSelf (#767)

This replaces all usages of `LazyCell` (which is not thread safe) with
`OnceCell`, which is and will also be available as `std::sync::OnceLock`
in the future.

Author: Swatinem

CHANGELOG.md

@@ -1,5 +1,11 @@
 # Changelog
 
+## Unreleased
+
+**Features**:
+
+- Replace internal usage of `LazyCell` by `OnceCell` and make `SourceBundleDebugSession`: `Send`, `Sync` and `AsSelf`. ([#767](https://github.com/getsentry/symbolic/pull/767))
+
 ## 12.0.0
 
 **Features**:

symbolic-debuginfo/Cargo.toml

@@ -25,7 +25,7 @@ default = ["breakpad", "elf", "macho", "ms", "ppdb", "sourcebundle", "js", "wasm
 # Breakpad text format parsing and processing
 breakpad = ["nom", "nom-supreme", "regex"]
 # DWARF processing.
-dwarf = ["gimli", "lazycell"]
+dwarf = ["gimli", "once_cell"]
 # ELF reading
 elf = [
     "dwarf",
@@ -53,7 +53,7 @@ ms = [
     "goblin/pe32",
     "goblin/pe64",
     "goblin/std",
-    "lazycell",
+    "once_cell",
     "parking_lot",
     "pdb-addr2line",
     "scroll",
@@ -65,7 +65,7 @@ ppdb = [
 # Source bundle creation
 sourcebundle = [
     "lazy_static",
-    "lazycell",
+    "once_cell",
     "parking_lot",
     "regex",
     "serde_json",
@@ -94,7 +94,7 @@ gimli = { version = "0.27.0", optional = true, default-features = false, feature
 ] }
 goblin = { version = "0.6.0", optional = true, default-features = false }
 lazy_static = { version = "1.4.0", optional = true }
-lazycell = { version = "1.2.1", optional = true }
+once_cell = { version = "1.17.1", optional = true }
 nom = { version = "7.0.0", optional = true }
 nom-supreme = { version = "0.8.0", optional = true }
 parking_lot = { version = "0.12.0", optional = true }

symbolic-debuginfo/src/dwarf.rs

@@ -20,7 +20,7 @@ use std::sync::Arc;
 use fallible_iterator::FallibleIterator;
 use gimli::read::{AttributeValue, Error as GimliError, Range};
 use gimli::{constants, DwarfFileType, UnitSectionOffset};
-use lazycell::LazyCell;
+use once_cell::sync::OnceCell;
 use thiserror::Error;
 
 use symbolic_common::{AsSelf, Language, Name, NameMangling, SelfCell};
@@ -1109,7 +1109,7 @@ impl<'data> DwarfSections<'data> {
 struct DwarfInfo<'data> {
     inner: DwarfInner<'data>,
     headers: Vec<UnitHeader<'data>>,
-    units: Vec<LazyCell<Option<Unit<'data>>>>,
+    units: Vec<OnceCell<Option<Unit<'data>>>>,
     symbol_map: SymbolMap<'data>,
     address_offset: i64,
     kind: ObjectKind,
@@ -1153,7 +1153,7 @@ impl<'d> DwarfInfo<'d> {
 
         // Prepare random access to unit headers.
         let headers = inner.units().collect::<Vec<_>>()?;
-        let units = headers.iter().map(|_| LazyCell::new()).collect();
+        let units = headers.iter().map(|_| OnceCell::new()).collect();
 
         Ok(DwarfInfo {
             inner,
@@ -1173,7 +1173,7 @@ impl<'d> DwarfInfo<'d> {
             None => return Ok(None),
         };
 
-        let unit_opt = cell.try_borrow_with(|| {
+        let unit_opt = cell.get_or_try_init(|| {
             // Parse the compilation unit from the header. This requires a top-level DIE that
             // describes the unit itself. For some older DWARF files, this DIE might be missing
             // which causes gimli to error out. We prefer to skip them silently as this simply marks

symbolic-debuginfo/src/ppdb.rs

@@ -4,7 +4,7 @@ use std::collections::HashMap;
 use std::fmt;
 use std::iter;
 
-use lazycell::LazyCell;
+use once_cell::sync::OnceCell;
 use symbolic_common::{Arch, CodeId, DebugId};
 use symbolic_ppdb::EmbeddedSource;
 use symbolic_ppdb::{Document, FormatError, PortablePdb};
@@ -143,7 +143,7 @@ impl fmt::Debug for PortablePdbObject<'_> {
 /// A debug session for a Portable PDB object.
 pub struct PortablePdbDebugSession<'data> {
     ppdb: PortablePdb<'data>,
-    sources: LazyCell<HashMap<String, PPDBSource<'data>>>,
+    sources: OnceCell<HashMap<String, PPDBSource<'data>>>,
 }
 
 #[derive(Debug, Clone)]
@@ -156,7 +156,7 @@ impl<'data> PortablePdbDebugSession<'data> {
     fn new(ppdb: &'_ PortablePdb<'data>) -> Result<Self, FormatError> {
         Ok(PortablePdbDebugSession {
             ppdb: ppdb.clone(),
-            sources: LazyCell::new(),
+            sources: OnceCell::new(),
         })
     }
 
@@ -196,7 +196,7 @@ impl<'data> PortablePdbDebugSession<'data> {
         &self,
         path: &str,
     ) -> Result<Option<SourceFileDescriptor<'_>>, FormatError> {
-        let sources = self.sources.borrow_with(|| self.init_sources());
+        let sources = self.sources.get_or_init(|| self.init_sources());
         match sources.get(path) {
             None => Ok(None),
             Some(PPDBSource::Embedded(source)) => source.get_contents().map(|bytes| {

symbolic-debuginfo/src/sourcebundle.rs

@@ -51,7 +51,7 @@ use std::io::{BufReader, BufWriter, Read, Seek, Write};
 use std::path::Path;
 use std::sync::Arc;
 
-use lazycell::LazyCell;
+use once_cell::sync::OnceCell;
 use parking_lot::Mutex;
 use regex::Regex;
 use serde::{Deserialize, Deserializer, Serialize};
@@ -676,7 +676,7 @@ impl<'data> SourceBundle<'data> {
         Ok(SourceBundleDebugSession {
             manifest: self.manifest.clone(),
             archive: self.archive.clone(),
-            indexed_files: LazyCell::new(),
+            indexed_files: OnceCell::new(),
         })
     }
 
@@ -802,7 +802,7 @@ enum FileKey<'a> {
 pub struct SourceBundleDebugSession<'data> {
     manifest: Arc<SourceBundleManifest>,
     archive: Arc<Mutex<zip::read::ZipArchive<std::io::Cursor<&'data [u8]>>>>,
-    indexed_files: LazyCell<HashMap<FileKey<'data>, Arc<String>>>,
+    indexed_files: OnceCell<HashMap<FileKey<'data>, Arc<String>>>,
 }
 
 impl<'data> SourceBundleDebugSession<'data> {
@@ -820,7 +820,7 @@ impl<'data> SourceBundleDebugSession<'data> {
 
     /// Get the indexed file mapping.
     fn indexed_files(&self) -> &HashMap<FileKey, Arc<String>> {
-        self.indexed_files.borrow_with(|| {
+        self.indexed_files.get_or_init(|| {
             let files = &self.manifest.files;
             let mut rv = HashMap::with_capacity(files.len());
 
@@ -928,6 +928,14 @@ impl<'data, 'session> DebugSession<'session> for SourceBundleDebugSession<'data>
     }
 }
 
+impl<'slf, 'data: 'slf> AsSelf<'slf> for SourceBundleDebugSession<'data> {
+    type Ref = SourceBundleDebugSession<'slf>;
+
+    fn as_self(&'slf self) -> &Self::Ref {
+        unsafe { std::mem::transmute(self) }
+    }
+}
+
 /// An iterator over source files in a SourceBundle object.
 pub struct SourceBundleFileIterator<'s> {
     files: std::collections::btree_map::Values<'s, String, SourceFileInfo>,
@@ -1362,6 +1370,12 @@ mod tests {
         Ok(())
     }
 
+    #[test]
+    fn debugsession_is_sendsync() {
+        fn is_sendsync<T: Send + Sync>() {}
+        is_sendsync::<SourceBundleDebugSession>();
+    }
+
     #[test]
     fn test_source_descriptor() -> Result<(), SourceBundleError> {
         let mut writer = Cursor::new(Vec::new());