feat(jrsonnet-evaluator): implement gc

Some manual Trace/Finalize implementations can be replaced with derives
with Manishearth/rust-gc#116 getting merged

Signed-off-by: Yaroslav Bolyukin <[email protected]>

crates/jrsonnet-evaluator/Cargo.toml

@@ -30,13 +30,12 @@ jrsonnet-stdlib = { path = "../jrsonnet-stdlib", version = "0.3.7" }
 jrsonnet-types = { path = "../jrsonnet-types", version = "0.3.7" }
 pathdiff = "0.2.0"
 
-closure = "0.3.0"
-
 md5 = "0.7.0"
 base64 = "0.13.0"
 rustc-hash = "1.1.0"
 
 thiserror = "1.0"
+gc = { version = "0.4.1", features = ["derive"] }
 
 [dependencies.anyhow]
 version = "1.0"

crates/jrsonnet-evaluator/src/builtin/format.rs

@@ -2,11 +2,12 @@
 #![allow(clippy::too_many_arguments)]
 
 use crate::{error::Error::*, throw, LocError, ObjValue, Result, Val};
+use gc::{Finalize, Trace};
 use jrsonnet_interner::IStr;
 use jrsonnet_types::ValType;
 use thiserror::Error;
 
-#[derive(Debug, Clone, Error)]
+#[derive(Debug, Clone, Error, Trace, Finalize)]
 pub enum FormatError {
 	#[error("truncated format code")]
 	TruncatedFormatCode,

crates/jrsonnet-evaluator/src/builtin/manifest.rs

@@ -126,6 +126,7 @@ fn manifest_json_ex_buf(
 			buf.push('}');
 		}
 		Val::Func(_) => throw!(RuntimeError("tried to manifest function".into())),
+		Val::DebugGcTraceValue(v) => manifest_json_ex_buf(&v.value, buf, cur_padding, options)?,
 	};
 	Ok(())
 }

crates/jrsonnet-evaluator/src/builtin/mod.rs

@@ -1,10 +1,11 @@
 use crate::{
 	equals,
 	error::{Error::*, Result},
-	parse_args, primitive_equals, push, throw, with_state, ArrValue, Context, EvaluationState,
-	FuncVal, LazyVal, Val,
+	parse_args, primitive_equals, push, throw, with_state, ArrValue, Context, DebugGcTraceValue,
+	EvaluationState, FuncVal, LazyVal, Val,
 };
 use format::{format_arr, format_obj};
+use gc::Gc;
 use jrsonnet_interner::IStr;
 use jrsonnet_parser::{ArgsDesc, BinaryOpType, ExprLocation};
 use jrsonnet_types::ty;
@@ -68,6 +69,8 @@ thread_local! {
 			("md5".into(), builtin_md5),
 			("base64".into(), builtin_base64),
 			("trace".into(), builtin_trace),
+			("gc".into(), builtin_gc),
+			("gcTrace".into(), builtin_gc_trace),
 			("join".into(), builtin_join),
 			("escapeStringJson".into(), builtin_escape_string_json),
 			("manifestJsonEx".into(), builtin_manifest_json_ex),
@@ -301,7 +304,7 @@ fn builtin_native(context: Context, _loc: Option<&ExprLocation>, args: &ArgsDesc
 	parse_args!(context, "native", args, 1, [
 		0, x: ty!(string) => Val::Str;
 	], {
-		Ok(with_state(|s| s.settings().ext_natives.get(&x).cloned()).map(|v| Val::Func(Rc::new(FuncVal::NativeExt(x.clone(), v)))).ok_or(UndefinedExternalFunction(x))?)
+		Ok(with_state(|s| s.settings().ext_natives.get(&x).cloned()).map(|v| Val::Func(Gc::new(FuncVal::NativeExt(x.clone(), v)))).ok_or(UndefinedExternalFunction(x))?)
 	})
 }
 
@@ -446,6 +449,28 @@ fn builtin_trace(context: Context, loc: Option<&ExprLocation>, args: &ArgsDesc)
 	})
 }
 
+fn builtin_gc(context: Context, _loc: Option<&ExprLocation>, args: &ArgsDesc) -> Result<Val> {
+	parse_args!(context, "gc", args, 1, [
+		0, rest: ty!(any);
+	], {
+		println!("GC start");
+		gc::force_collect();
+		println!("GC done");
+
+		Ok(rest)
+	})
+}
+
+fn builtin_gc_trace(context: Context, _loc: Option<&ExprLocation>, args: &ArgsDesc) -> Result<Val> {
+	parse_args!(context, "gcTrace", args, 2, [
+		0, name: ty!(string) => Val::Str;
+		1, rest: ty!(any);
+	], {
+
+		Ok(DebugGcTraceValue::new(name, rest))
+	})
+}
+
 fn builtin_base64(context: Context, _loc: Option<&ExprLocation>, args: &ArgsDesc) -> Result<Val> {
 	parse_args!(context, "base64", args, 1, [
 		0, input: ty!((string | (Array<number>)));

crates/jrsonnet-evaluator/src/builtin/sort.rs

@@ -2,9 +2,9 @@ use crate::{
 	error::{Error, LocError, Result},
 	throw, Context, FuncVal, Val,
 };
-use std::rc::Rc;
+use gc::{Finalize, Gc, Trace};
 
-#[derive(Debug, Clone, thiserror::Error)]
+#[derive(Debug, Clone, thiserror::Error, Trace, Finalize)]
 pub enum SortError {
 	#[error("sort key should be string or number")]
 	SortKeyShouldBeStringOrNumber,
@@ -59,13 +59,13 @@ fn get_sort_type<T>(
 	Ok(sort_type)
 }
 
-pub fn sort(ctx: Context, mut values: Rc<Vec<Val>>, key_getter: &FuncVal) -> Result<Rc<Vec<Val>>> {
+pub fn sort(ctx: Context, values: Gc<Vec<Val>>, key_getter: &FuncVal) -> Result<Gc<Vec<Val>>> {
 	if values.len() <= 1 {
 		return Ok(values);
 	}
 	if key_getter.is_ident() {
-		let mvalues = Rc::make_mut(&mut values);
-		let sort_type = get_sort_type(mvalues, |k| k)?;
+		let mut mvalues = (*values).clone();
+		let sort_type = get_sort_type(&mut mvalues, |k| k)?;
 		match sort_type {
 			SortKeyType::Number => mvalues.sort_by_key(|v| match v {
 				Val::Num(n) => NonNaNf64(*n),
@@ -77,7 +77,7 @@ pub fn sort(ctx: Context, mut values: Rc<Vec<Val>>, key_getter: &FuncVal) -> Res
 			}),
 			SortKeyType::Unknown => unreachable!(),
 		};
-		Ok(values)
+		Ok(Gc::new(mvalues))
 	} else {
 		let mut vk = Vec::with_capacity(values.len());
 		for value in values.iter() {
@@ -98,6 +98,6 @@ pub fn sort(ctx: Context, mut values: Rc<Vec<Val>>, key_getter: &FuncVal) -> Res
 			}),
 			SortKeyType::Unknown => unreachable!(),
 		};
-		Ok(Rc::new(vk.into_iter().map(|v| v.0).collect()))
+		Ok(Gc::new(vk.into_iter().map(|v| v.0).collect()))
 	}
 }

crates/jrsonnet-evaluator/src/ctx.rs

@@ -1,13 +1,14 @@
 use crate::{
-	error::Error::*, map::LayeredHashMap, resolved_lazy_val, FutureWrapper, LazyBinding, LazyVal,
-	ObjValue, Result, Val,
+	error::Error::*, map::LayeredHashMap, FutureWrapper, LazyBinding, LazyVal, ObjValue, Result,
+	Val,
 };
+use gc::{Finalize, Gc, Trace};
 use jrsonnet_interner::IStr;
 use rustc_hash::FxHashMap;
+use std::fmt::Debug;
 use std::hash::BuildHasherDefault;
-use std::{fmt::Debug, rc::Rc};
 
-#[derive(Clone)]
+#[derive(Clone, Trace, Finalize)]
 pub struct ContextCreator(pub Context, pub FutureWrapper<FxHashMap<IStr, LazyBinding>>);
 impl ContextCreator {
 	pub fn create(&self, this: Option<ObjValue>, super_obj: Option<ObjValue>) -> Result<Context> {
@@ -20,6 +21,7 @@ impl ContextCreator {
 	}
 }
 
+#[derive(Trace, Finalize)]
 struct ContextInternals {
 	dollar: Option<ObjValue>,
 	this: Option<ObjValue>,
@@ -28,15 +30,12 @@ struct ContextInternals {
 }
 impl Debug for ContextInternals {
 	fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
-		f.debug_struct("Context")
-			.field("this", &self.this.as_ref().map(|e| Rc::as_ptr(&e.0)))
-			.field("bindings", &self.bindings)
-			.finish()
+		f.debug_struct("Context").finish()
 	}
 }
 
-#[derive(Debug, Clone)]
-pub struct Context(Rc<ContextInternals>);
+#[derive(Debug, Clone, Trace, Finalize)]
+pub struct Context(Gc<ContextInternals>);
 impl Context {
 	pub fn new_future() -> FutureWrapper<Self> {
 		FutureWrapper::new()
@@ -55,7 +54,7 @@ impl Context {
 	}
 
 	pub fn new() -> Self {
-		Self(Rc::new(ContextInternals {
+		Self(Gc::new(ContextInternals {
 			dollar: None,
 			this: None,
 			super_obj: None,
@@ -81,7 +80,7 @@ impl Context {
 	pub fn with_var(self, name: IStr, value: Val) -> Self {
 		let mut new_bindings =
 			FxHashMap::with_capacity_and_hasher(1, BuildHasherDefault::default());
-		new_bindings.insert(name, resolved_lazy_val!(value));
+		new_bindings.insert(name, LazyVal::new_resolved(value));
 		self.extend(new_bindings, None, None, None)
 	}
 
@@ -96,40 +95,21 @@ impl Context {
 		new_this: Option<ObjValue>,
 		new_super_obj: Option<ObjValue>,
 	) -> Self {
-		match Rc::try_unwrap(self.0) {
-			Ok(mut ctx) => {
-				// Extended context aren't used by anything else, we can freely mutate it without cloning
-				if let Some(dollar) = new_dollar {
-					ctx.dollar = Some(dollar);
-				}
-				if let Some(this) = new_this {
-					ctx.this = Some(this);
-				}
-				if let Some(super_obj) = new_super_obj {
-					ctx.super_obj = Some(super_obj);
-				}
-				if !new_bindings.is_empty() {
-					ctx.bindings = ctx.bindings.extend(new_bindings);
-				}
-				Self(Rc::new(ctx))
-			}
-			Err(ctx) => {
-				let dollar = new_dollar.or_else(|| ctx.dollar.clone());
-				let this = new_this.or_else(|| ctx.this.clone());
-				let super_obj = new_super_obj.or_else(|| ctx.super_obj.clone());
-				let bindings = if new_bindings.is_empty() {
-					ctx.bindings.clone()
-				} else {
-					ctx.bindings.clone().extend(new_bindings)
-				};
-				Self(Rc::new(ContextInternals {
-					dollar,
-					this,
-					super_obj,
-					bindings,
-				}))
-			}
-		}
+		let ctx = &self.0;
+		let dollar = new_dollar.or_else(|| ctx.dollar.clone());
+		let this = new_this.or_else(|| ctx.this.clone());
+		let super_obj = new_super_obj.or_else(|| ctx.super_obj.clone());
+		let bindings = if new_bindings.is_empty() {
+			ctx.bindings.clone()
+		} else {
+			ctx.bindings.clone().extend(new_bindings)
+		};
+		Self(Gc::new(ContextInternals {
+			dollar,
+			this,
+			super_obj,
+			bindings,
+		}))
 	}
 	pub fn extend_bound(self, new_bindings: FxHashMap<IStr, LazyVal>) -> Self {
 		let new_this = self.0.this.clone();
@@ -166,22 +146,6 @@ impl Default for Context {
 
 impl PartialEq for Context {
 	fn eq(&self, other: &Self) -> bool {
-		Rc::ptr_eq(&self.0, &other.0)
-	}
-}
-
-#[cfg(feature = "unstable")]
-#[derive(Debug, Clone)]
-pub struct WeakContext(std::rc::Weak<ContextInternals>);
-#[cfg(feature = "unstable")]
-impl WeakContext {
-	pub fn upgrade(&self) -> Context {
-		Context(self.0.upgrade().expect("context is removed"))
-	}
-}
-#[cfg(feature = "unstable")]
-impl PartialEq for WeakContext {
-	fn eq(&self, other: &Self) -> bool {
-		self.0.ptr_eq(&other.0)
+		Gc::ptr_eq(&self.0, &other.0)
 	}
 }

crates/jrsonnet-evaluator/src/dynamic.rs

@@ -1,23 +1,23 @@
-use std::{cell::RefCell, rc::Rc};
+use gc::{Finalize, Gc, GcCell, Trace};
 
-#[derive(Clone)]
-pub struct FutureWrapper<V>(pub Rc<RefCell<Option<V>>>);
-impl<T> FutureWrapper<T> {
+#[derive(Clone, Trace, Finalize)]
+pub struct FutureWrapper<V: Trace + 'static>(pub Gc<GcCell<Option<V>>>);
+impl<T: Trace + 'static> FutureWrapper<T> {
 	pub fn new() -> Self {
-		Self(Rc::new(RefCell::new(None)))
+		Self(Gc::new(GcCell::new(None)))
 	}
 	pub fn fill(self, value: T) {
 		assert!(self.0.borrow().is_none(), "wrapper is filled already");
 		self.0.borrow_mut().replace(value);
 	}
 }
-impl<T: Clone> FutureWrapper<T> {
+impl<T: Clone + Trace + 'static> FutureWrapper<T> {
 	pub fn unwrap(&self) -> T {
 		self.0.borrow().as_ref().cloned().unwrap()
 	}
 }
 
-impl<T> Default for FutureWrapper<T> {
+impl<T: Trace + 'static> Default for FutureWrapper<T> {
 	fn default() -> Self {
 		Self::new()
 	}

crates/jrsonnet-evaluator/src/error.rs

@@ -2,13 +2,14 @@ use crate::{
 	builtin::{format::FormatError, sort::SortError},
 	typed::TypeLocError,
 };
+use gc::{Finalize, Trace};
 use jrsonnet_interner::IStr;
 use jrsonnet_parser::{BinaryOpType, ExprLocation, UnaryOpType};
 use jrsonnet_types::ValType;
 use std::{path::PathBuf, rc::Rc};
 use thiserror::Error;
 
-#[derive(Error, Debug, Clone)]
+#[derive(Error, Debug, Clone, Trace, Finalize)]
 pub enum Error {
 	#[error("intrinsic not found: {0}")]
 	IntrinsicNotFound(IStr),
@@ -88,13 +89,16 @@ pub enum Error {
 	ImportSyntaxError {
 		path: Rc<PathBuf>,
 		source_code: IStr,
+		#[unsafe_ignore_trace]
 		error: Box<jrsonnet_parser::ParseError>,
 	},
 
 	#[error("runtime error: {0}")]
 	RuntimeError(IStr),
 	#[error("stack overflow, try to reduce recursion, or set --max-stack to bigger value")]
 	StackOverflow,
+	#[error("infinite recursion detected")]
+	RecursiveLazyValueEvaluation,
 	#[error("tried to index by fractional value")]
 	FractionalIndex,
 	#[error("attempted to divide by zero")]
@@ -142,15 +146,15 @@ impl From<Error> for LocError {
 	}
 }
 
-#[derive(Clone, Debug)]
+#[derive(Clone, Debug, Trace, Finalize)]
 pub struct StackTraceElement {
 	pub location: Option<ExprLocation>,
 	pub desc: String,
 }
-#[derive(Debug, Clone)]
+#[derive(Debug, Clone, Trace, Finalize)]
 pub struct StackTrace(pub Vec<StackTraceElement>);
 
-#[derive(Debug, Clone)]
+#[derive(Debug, Clone, Trace, Finalize)]
 pub struct LocError(Box<(Error, StackTrace)>);
 impl LocError {
 	pub fn new(e: Error) -> Self {