perf: improve EIP-3155 tracer

- Buffer stderr
- Allocate less

Author: DaniPopes

bins/revme/src/cmd/statetest/runner.rs

@@ -427,7 +427,7 @@ pub fn execute_test_suite(
 
                     let timer = Instant::now();
                     let res = ctx.inspect_commit_previous(
-                        TracerEip3155::new(Box::new(stderr())).without_summary(),
+                        TracerEip3155::buffered(stderr()).without_summary(),
                     );
                     *elapsed.lock().unwrap() += timer.elapsed();
 
@@ -497,9 +497,8 @@ pub fn execute_test_suite(
                     .with_tx(&tx)
                     .with_cfg(&cfg);
 
-                let _ = ctx.inspect_commit_previous(
-                    TracerEip3155::new(Box::new(stderr())).without_summary(),
-                );
+                let _ = ctx
+                    .inspect_commit_previous(TracerEip3155::buffered(stderr()).without_summary());
 
                 println!("\nExecution result: {exec_result:#?}");
                 println!("\nExpected exception: {:?}", test.expect_exception);

crates/inspector/src/eip3155.rs

@@ -38,7 +38,7 @@ pub struct TracerEip3155<CTX, INTR> {
 // The CUT MUST output a `json` object for EACH operation.
 #[derive(Serialize)]
 #[serde(rename_all = "camelCase")]
-struct Output {
+struct Output<'a> {
     // Required fields:
     /// Program counter
     pc: u64,
@@ -48,22 +48,26 @@ struct Output {
     /// OpCode
     op: u8,
     /// Gas left before executing this operation
-    gas: String,
+    #[serde(serialize_with = "serde_hex_u64")]
+    gas: u64,
     /// Gas cost of this operation
-    gas_cost: String,
+    #[serde(serialize_with = "serde_hex_u64")]
+    gas_cost: u64,
     /// Array of all values on the stack
-    stack: Vec<String>,
+    stack: &'a [U256],
     /// Depth of the call stack
     depth: u64,
     /// Depth of the EOF function call stack
     #[serde(default, skip_serializing_if = "Option::is_none")]
     function_depth: Option<u64>,
     /// Data returned by the function call
-    return_data: String,
+    return_data: &'static str,
     /// Amount of **global** gas refunded
-    refund: String,
+    #[serde(serialize_with = "serde_hex_u64")]
+    refund: u64,
     /// Size of memory array
-    mem_size: String,
+    #[serde(serialize_with = "serde_hex_u64")]
+    mem_size: u64,
 
     // Optional fields:
     /// Name of the operation
@@ -93,7 +97,8 @@ struct Summary {
     /// Return values of the function
     output: String,
     /// All gas used by the transaction
-    gas_used: String,
+    #[serde(serialize_with = "serde_hex_u64")]
+    gas_used: u64,
     /// Bool whether transaction was executed successfully
     pass: bool,
 
@@ -111,35 +116,13 @@ where
     CTX: CfgGetter + TransactionGetter,
     INTR:,
 {
-    /// Sets the writer to use for the output.
-    pub fn set_writer(&mut self, writer: Box<dyn Write>) {
-        self.output = writer;
-    }
-
-    /// Resets the Tracer to its initial state of [Self::new].
-    /// This makes the inspector ready to be used again.
-    pub fn clear(&mut self) {
-        let Self {
-            gas_inspector,
-            stack,
-            pc,
-            opcode,
-            gas,
-            refunded,
-            mem_size,
-            skip,
-            ..
-        } = self;
-        *gas_inspector = GasInspector::new();
-        stack.clear();
-        *pc = 0;
-        *opcode = 0;
-        *gas = 0;
-        *refunded = 0;
-        *mem_size = 0;
-        *skip = false;
+    /// Creates a new EIP-3155 tracer with the given output writer, by first wrapping it in a
+    /// [`BufWriter`](std::io::BufWriter).
+    pub fn buffered(output: impl Write + 'static) -> Self {
+        Self::new(Box::new(std::io::BufWriter::new(output)))
     }
 
+    /// Creates a new EIP-3155 tracer with the given output writer.
     pub fn new(output: Box<dyn Write>) -> Self {
         Self {
             output,
@@ -160,6 +143,11 @@ where
         }
     }
 
+    /// Sets the writer to use for the output.
+    pub fn set_writer(&mut self, writer: Box<dyn Write>) {
+        self.output = writer;
+    }
+
     /// Don't include a summary at the end of the trace
     pub fn without_summary(mut self) -> Self {
         self.print_summary = false;
@@ -172,10 +160,29 @@ where
         self
     }
 
-    fn write_value(&mut self, value: &impl serde::Serialize) -> std::io::Result<()> {
-        serde_json::to_writer(&mut *self.output, value)?;
-        self.output.write_all(b"\n")?;
-        self.output.flush()
+    /// Resets the tracer to its initial state of [`Self::new`].
+    ///
+    /// This makes the inspector ready to be used again.
+    pub fn clear(&mut self) {
+        let Self {
+            gas_inspector,
+            stack,
+            pc,
+            opcode,
+            gas,
+            refunded,
+            mem_size,
+            skip,
+            ..
+        } = self;
+        *gas_inspector = GasInspector::new();
+        stack.clear();
+        *pc = 0;
+        *opcode = 0;
+        *gas = 0;
+        *refunded = 0;
+        *mem_size = 0;
+        *skip = false;
     }
 
     fn print_summary(&mut self, result: &InterpreterResult, context: &mut CTX) {
@@ -185,23 +192,27 @@ where
             let value = Summary {
                 state_root: B256::ZERO.to_string(),
                 output: result.output.to_string(),
-                gas_used: hex_number(gas_limit - self.gas_inspector.gas_remaining()),
+                gas_used: gas_limit - self.gas_inspector.gas_remaining(),
                 pass: result.is_ok(),
                 time: None,
                 fork: Some(spec.to_string()),
             };
             let _ = self.write_value(&value);
         }
     }
+
+    fn write_value(&mut self, value: &impl serde::Serialize) -> std::io::Result<()> {
+        write_value(&mut *self.output, value)
+    }
 }
 
 pub trait CloneStack {
-    fn clone_from(&self) -> Vec<U256>;
+    fn clone_into(&self, stack: &mut Vec<U256>);
 }
 
 impl CloneStack for Stack {
-    fn clone_from(&self) -> Vec<U256> {
-        self.data().to_vec()
+    fn clone_into(&self, stack: &mut Vec<U256>) {
+        stack.extend_from_slice(self.data());
     }
 }
 
@@ -216,10 +227,11 @@ where
 
     fn step(&mut self, interp: &mut Interpreter<INTR>, _: &mut CTX) {
         self.gas_inspector.step(interp.control.gas());
-        self.stack = interp.stack.clone_from();
+        self.stack.clear();
+        interp.stack.clone_into(&mut self.stack);
         self.memory = if self.include_memory {
             Some(hex::encode_prefixed(
-                interp.memory.slice(0..usize::MAX).as_ref(),
+                interp.memory.slice(0..interp.memory.size()).as_ref(),
             ))
         } else {
             None
@@ -252,14 +264,14 @@ where
             pc: self.pc,
             section: self.section,
             op: self.opcode,
-            gas: hex_number(self.gas),
-            gas_cost: hex_number(self.gas_inspector.last_gas_cost()),
-            stack: self.stack.iter().map(hex_number_u256).collect(),
+            gas: self.gas,
+            gas_cost: self.gas_inspector.last_gas_cost(),
+            stack: &self.stack,
             depth: context.journal().depth() as u64,
             function_depth: self.function_depth,
-            return_data: "0x".to_string(),
-            refund: hex_number(self.refunded as u64),
-            mem_size: self.mem_size.to_string(),
+            return_data: "0x",
+            refund: self.refunded as u64,
+            mem_size: self.mem_size as u64,
 
             op_name: OpCode::new(self.opcode).map(|i| i.as_str()),
             error: if !interp.control.instruction_result().is_ok() {
@@ -271,15 +283,15 @@ where
             storage: None,
             return_stack: None,
         };
-        let _ = self.write_value(&value);
+        let _ = write_value(&mut self.output, &value);
     }
 
     fn call_end(&mut self, context: &mut CTX, _: &CallInputs, outcome: &mut CallOutcome) {
         self.gas_inspector.call_end(outcome);
 
         if context.journal().depth() == 0 {
             self.print_summary(&outcome.result, context);
-            // Clear the state if we are at the top level
+            // Clear the state if we are at the top level.
             self.clear();
         }
     }
@@ -289,23 +301,20 @@ where
 
         if context.journal().depth() == 0 {
             self.print_summary(&outcome.result, context);
-
-            // Clear the state if we are at the top level
+            // Clear the state if we are at the top level.
             self.clear();
         }
     }
 }
 
-fn hex_number(uint: u64) -> String {
-    format!("0x{uint:x}")
+fn write_value(
+    output: &mut dyn std::io::Write,
+    value: &impl serde::Serialize,
+) -> std::io::Result<()> {
+    serde_json::to_writer(&mut *output, value)?;
+    output.write_all(b"\n")
 }
 
-fn hex_number_u256(b: &U256) -> String {
-    let s = hex::encode(b.to_be_bytes::<32>());
-    let s = s.trim_start_matches('0');
-    if s.is_empty() {
-        "0x0".to_string()
-    } else {
-        format!("0x{s}")
-    }
+fn serde_hex_u64<S: serde::Serializer>(n: &u64, serializer: S) -> Result<S::Ok, S::Error> {
+    serializer.serialize_str(&format!("{:#x}", *n))
 }