30-清理时间 - 你想构建一个语言虚拟机吗？
引言
虽然处理集群化工作非常有趣，但我们积累 (accumulated) 了相当多的技术债务 (technical debt)。有大量的警告，我甚至不敢运行 clippy。因此，这篇文章全是关于逐一清理这些警告的。它可能不会像添加功能那样令人兴奋，但是确保花时间进行清理同样重要，甚至更为重要。技术债务的增长速度有时比信用卡 (credit card) 债务还要快。
范围
让我们通过在master分支上的最新提交运行cargo check来看看我们面临的问题。
Checking iridium v0.0.29 (file:///Users/fletcher/Projects/subnetzero/iridium)
warning: unused import: `std::fmt`
--> src/assembler/mod.rs:12:5
|
12 | use std::fmt;
| ^^^^^^^^
|
= note: #[warn(unused_imports)] on by default
warning: unused import: `log`
--> src/assembler/mod.rs:16:5
|
16 | use log;
| ^^^
warning: unused imports: `Arc`, `RwLock`
--> src/repl/mod.rs:9:17
|
9 | use std::sync::{RwLock, Arc, mpsc};
| ^^^^^^ ^^^
warning: unused import: `cluster::manager::Manager`
--> src/repl/mod.rs:18:5
|
18 | use cluster::manager::Manager;
| ^^^^^^^^^^^^^^^^^^^^^^^^^
warning: unused import: `Assembler`
--> src/vm.rs:12:55
|
12 | use assembler::{PIE_HEADER_LENGTH, PIE_HEADER_PREFIX, Assembler};
| ^^^^^^^^^
warning: unused import: `RwLock`
--> src/cluster/client.rs:5:22
|
5 | use std::sync::{Arc, RwLock, Mutex};
| ^^^^^^
warning: unused import: `cluster::message::IridiumMessage`
--> src/cluster/client.rs:9:5
|
9 | use cluster::message::IridiumMessage;
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
warning: unused import: `cluster::manager::Manager`
--> src/cluster/client.rs:10:5
|
10 | use cluster::manager::Manager;
| ^^^^^^^^^^^^^^^^^^^^^^^^^
warning: unused imports: `Arc`, `RwLock`
--> src/cluster/mod.rs:6:17
|
6 | use std::sync::{Arc, RwLock};
| ^^^ ^^^^^^
warning: unused variable: `bytes_read`
--> src/cluster/server.rs:18:17
|
18 | let bytes_read = client.reader.read(&mut buf);
| ^^^^^^^^^^ help: consider using `_bytes_read` instead
|
= note: #[warn(unused_variables)] on by default
warning: unused variable: `connection_manager`
--> src/cluster/server.rs:9:33
|
9 | pub fn listen(addr: SocketAddr, connection_manager: Arc<RwLock<Manager>>) {
| ^^^^^^^^^^^^^^^^^^ help: consider using `_connection_manager` instead
warning: unused variable: `args`
--> src/repl/mod.rs:342:35
|
342 | fn cluster_members(&mut self, args: &[&str]) {
| ^^^^ help: consider using `_args` instead
warning: unused variable: `offset`
--> src/vm.rs:458:21
|
458 | let offset = self.registers[self.next_8_bits() as usize] as usize;
| ^^^^^^ help: consider using `_offset` instead
warning: field is never used: `tx`
--> src/cluster/client.rs:17:5
|
17 | tx: Option<Arc<Mutex<Sender<String>>>>,
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
|
= note: #[warn(dead_code)] on by default
warning: method is never used: `w`
--> src/cluster/client.rs:44:5
|
44 | fn w(&mut self, msg: &str) -> bool {
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
warning: type alias is never used: `NodeCollection`
--> src/cluster/mod.rs:11:1
|
11 | type NodeCollection = HashMap<NodeAlias, ClusterClient>;
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
warning: unused `std::result::Result` which must be used
--> src/vm.rs:461:17
|
461 | buf.as_mut().write_i32::<LittleEndian>(data);
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
|
= note: #[warn(unused_must_use)] on by default
= note: this `Result` may be an `Err` variant, which should be handled
warning: unused `std::result::Result` which must be used
--> src/vm.rs:466:17
|
466 | buf.as_mut().write_i32::<LittleEndian>(data);
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
|
= note: this `Result` may be an `Err` variant, which should be handled
warning: unused `std::result::Result` which must be used
--> src/cluster/client.rs:41:9
|
41 | self.raw_stream.write(&alias.as_bytes());
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
|
= note: this `Result` may be an `Err` variant, which should be handled
warning: unused variable: `events`
--> src/bin/iridium.rs:75:25
|
75 | let events = vm.run();
| ^^^^^^ help: consider using `_events` instead
|
= note: #[warn(unused_variables)] on by default
Finished dev [unoptimized + debuginfo] target(s) in 2.41s
所以……是的。情况并不太差。让我们看看cargo fmt是否能解决其中一些问题。
Rustfmt
我们有一个最小的.rustfmt.toml，但让我们生成一个默认的配置文件，我们可以使用：rustfmt --print-config default .rustfmt.toml。如果你查看里面，你会看到更多的规则。我不得不做一些调整，所以你将需要替换它为：
max_width = 100
hard_tabs = false
tab_spaces = 4
newline_style = "Auto"
use_small_heuristics = "Default"
indent_style = "Block"
wrap_comments = false
comment_width = 80
normalize_comments = false
format_strings = false
format_macro_matchers = false
format_macro_bodies = true
empty_item_single_line = true
struct_lit_single_line = true
fn_single_line = false
where_single_line = false
imports_indent = "Block"
imports_layout = "Mixed"
merge_imports = false
reorder_imports = true
reorder_modules = true
reorder_impl_items = false
type_punctuation_density = "Wide"
space_before_colon = false
space_after_colon = true
spaces_around_ranges = false
binop_separator = "Front"
remove_nested_parens = true
combine_control_expr = true
struct_field_align_threshold = 0
match_arm_blocks = true
force_multiline_blocks = false
fn_args_density = "Tall"
brace_style = "SameLineWhere"
control_brace_style = "AlwaysSameLine"
trailing_semicolon = true
trailing_comma = "Vertical"
match_block_trailing_comma = false
blank_lines_upper_bound = 1
blank_lines_lower_bound = 0
edition = "2018"
merge_derives = true
use_try_shorthand = false
use_field_init_shorthand = false
force_explicit_abi = true
condense_wildcard_suffixes = false
color = "Auto"
required_version = "0.99.5"
unstable_features = false
disable_all_formatting = false
skip_children = false
hide_parse_errors = false
error_on_line_overflow = false
error_on_unformatted = false
report_todo = "Never"
report_fixme = "Never"
ignore = []
emit_mode = "Files"
make_backup = false
确保你已经运行：
rustup toolchain install nightly
rustup component add rustfmt-preview --toolchain=nightly
然后实际进行格式化，运行：
现在如果我们运行cargo check……我们仍然看到很多未使用的导入。这些应该很容易清理！我不会在这篇文章中详细说明。=）
<时间流逝> (<time passes>)
所有都完成了！如果你对完整的代码感兴趣，请看这里：https://gitlab.com/subnetzero/iridium/commit/eee41a00b56351fc0310e77abcb48dfd3a125ef7
现在……让我们看看 Clippy
如果我们运行：cargo +nightly clippy，然后我们得到：
warning: redundant field names in struct initialization
--> src/repl/mod.rs:43:13
|
43 | vm: vm,
| ^^^^^^ help: replace it with: `vm`
|
= note: #[warn(clippy::redundant_field_names)] on by default
= help: for further information visit https://rust-lang-nursery.github.io/rust-clippy/v0.0.212/index.html#redundant_field_names
warning: returning the result of a let binding from a block. Consider returning the expression directly.
--> src/vm.rs:557:9
|
557 | starting_offset
| ^^^^^^^^^^^^^^^
|
= note: #[warn(clippy::let_and_return)] on by default
note: this expression can be directly returned
--> src/vm.rs:556:31
|
556 | let starting_offset = rdr.read_u32::<LittleEndian>().unwrap() as usize;
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
= help: for further information visit https://rust-lang-nursery.github.io/rust-clippy/v0.0.212/index.html#let_and_return
warning: using `clone` on a `Copy` type
--> src/assembler/mod.rs:358:46
|
358 | *starting_instruction = Some(self.current_instruction.clone())
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: try removing the `clone` call: `self.current_instruction`
|
= note: #[warn(clippy::clone_on_copy)] on by default
= help: for further information visit https://rust-lang-nursery.github.io/rust-clippy/v0.0.212/index.html#clone_on_copy
warning: using `clone` on a `Copy` type
--> src/assembler/mod.rs:364:46
|
364 | *starting_instruction = Some(self.current_instruction.clone())
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: try removing the `clone` call: `self.current_instruction`
|
= help: for further information visit https://rust-lang-nursery.github.io/rust-clippy/v0.0.212/index.html#clone_on_copy
warning: redundant pattern matching, consider using `is_ok()`
--> src/cluster/client.rs:38:16
|
38 | if let Ok(_) = self.raw_stream.write(&alias.as_bytes()) {
| -------^^^^^------------------------------------------- help: try this: `if self.raw_stream.write(&alias.as_bytes()).is_ok()`
|
= note: #[warn(clippy::if_let_redundant_pattern_matching)] on by default
= help: for further information visit https://rust-lang-nursery.github.io/rust-clippy/v0.0.212/index.html#if_let_redundant_pattern_matching
warning: this argument is passed by value, but not consumed in the function body
--> src/cluster/manager.rs:28:41
|
28 | pub fn del_client(&mut self, alias: NodeAlias) {
| ^^^^^^^^^ help: consider changing the type to: `&str`
|
= note: #[warn(clippy::needless_pass_by_value)] on by default
= help: for further information visit https://rust-lang-nursery.github.io/rust-clippy/v0.0.212/index.html#needless_pass_by_value
warning: you seem to want to iterate on a map's keys
--> src/cluster/manager.rs:34:27
|
34 | for (alias, _) in &self.clients {
| ^^^^^^^^^^^^^
|
= note: #[warn(clippy::for_kv_map)] on by default
= help: for further information visit https://rust-lang-nursery.github.io/rust-clippy/v0.0.212/index.html#for_kv_map
help: use the corresponding method
|
34 | for alias in self.clients.keys() {
| ^^^^^ ^^^^^^^^^^^^^^^^^^^
warning: this argument is passed by value, but not consumed in the function body
--> src/cluster/server.rs:9:54
|
9 | pub fn listen(addr: SocketAddr, _connection_manager: Arc<RwLock<Manager>>) {
| ^^^^^^^^^^^^^^^^^^^^ help: consider taking a reference instead: `&Arc<RwLock<Manager>>`
|
= help: for further information visit https://rust-lang-nursery.github.io/rust-clippy/v0.0.212/index.html#needless_pass_by_value
warning: useless use of `format!`
--> src/repl/mod.rs:319:27
|
319 | self.send_message(format!("Started cluster server!"));
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: consider using .to_string(): `"Started cluster server!".to_string()`
|
= note: #[warn(clippy::useless_format)] on by default
= help: for further information visit https://rust-lang-nursery.github.io/rust-clippy/v0.0.212/index.html#useless_format
warning: useless use of `format!`
--> src/repl/mod.rs:324:27
|
324 | self.send_message(format!("Attempting to join cluster..."));
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: consider using .to_string(): `"Attempting to join cluster...".to_string()`
|
= help: for further information visit https://rust-lang-nursery.github.io/rust-clippy/v0.0.212/index.html#useless_format
warning: useless use of `format!`
--> src/repl/mod.rs:329:31
|
329 | self.send_message(format!("Connected to cluster!"));
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: consider using .to_string(): `"Connected to cluster!".to_string()`
|
= help: for further information visit https://rust-lang-nursery.github.io/rust-clippy/v0.0.212/index.html#useless_format
warning: useless use of `format!`
--> src/repl/mod.rs:338:31
|
338 | self.send_message(format!("Could not connect to cluster!"));
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: consider using .to_string(): `"Could not connect to cluster!".to_string()`
|
= help: for further information visit https://rust-lang-nursery.github.io/rust-clippy/v0.0.212/index.html#useless_format
warning: useless use of `format!`
--> src/repl/mod.rs:343:27
|
343 | self.send_message(format!("Listing Known Nodes:"));
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: consider using .to_string(): `"Listing Known Nodes:".to_string()`
|
= help: for further information visit https://rust-lang-nursery.github.io/rust-clippy/v0.0.212/index.html#useless_format
warning: you don't need to add `&` to both the expression and the patterns
--> src/vm.rs:27:9
|
27 | / match &self {
28 | | &VMEventType::Start => 0,
29 | | &VMEventType::GracefulStop { code } => *code,
30 | | &VMEventType::Crash { code } => *code,
31 | | }
| |_________^
|
= note: #[warn(clippy::match_ref_pats)] on by default
= help: for further information visit https://rust-lang-nursery.github.io/rust-clippy/v0.0.212/index.html#match_ref_pats
help: try
|
27 | match self {
28 | VMEventType::Start => 0,
29 | VMEventType::GracefulStop { code } => *code,
30 | VMEventType::Crash { code } => *code,
|
warning: casting u8 to i32 may become silently lossy if types change
--> src/vm.rs:423:27
|
423 | let uv1 = self.next_8_bits() as i32;
| ^^^^^^^^^^^^^^^^^^^^^^^^^ help: try: `i32::from(self.next_8_bits())`
|
= note: #[warn(clippy::cast_lossless)] on by default
= help: for further information visit https://rust-lang-nursery.github.io/rust-clippy/v0.0.212/index.html#cast_lossless
warning: casting u8 to i32 may become silently lossy if types change
--> src/vm.rs:424:27
|
424 | let uv2 = self.next_8_bits() as i32;
| ^^^^^^^^^^^^^^^^^^^^^^^^^ help: try: `i32::from(self.next_8_bits())`
|
= help: for further information visit https://rust-lang-nursery.github.io/rust-clippy/v0.0.212/index.html#cast_lossless
warning: redundant pattern matching, consider using `is_ok()`
--> src/vm.rs:464:24
|
464 | if let Ok(_) = buf.as_mut().write_i32::<LittleEndian>(data) {
| -------^^^^^----------------------------------------------- help: try this: `if buf.as_mut().write_i32::<LittleEndian>(data).is_ok()`
|
= help: for further information visit https://rust-lang-nursery.github.io/rust-clippy/v0.0.212/index.html#if_let_redundant_pattern_matching
warning: the variable `c` is used as a loop counter. Consider using `for (c, item) in self.stack.drain(new_len..).enumerate()` or similar iterators
--> src/vm.rs:477:40
|
477 | for removed_element in self.stack.drain(new_len..) {
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^
|
= note: #[warn(clippy::explicit_counter_loop)] on by default
= help: for further information visit https://rust-lang-nursery.github.io/rust-clippy/v0.0.212/index.html#explicit_counter_loop
warning: the variable `c` is used as a loop counter. Consider using `for (c, item) in self.stack.drain(new_len..).enumerate()` or similar iterators
--> src/vm.rs:495:40
|
495 | for removed_element in self.stack.drain(new_len..) {
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^
|
= help: for further information visit https://rust-lang-nursery.github.io/rust-clippy/v0.0.212/index.html#explicit_counter_loop
Finished dev [unoptimized + debuginfo] target(s) in 12.96s
呼，好的。它们大部分是风格上/习惯性 (stylistic/idiomatic) 的问题。然而，这个警告是一个很好的发现：
warning: casting u8 to i32 may become silently lossy if types change
--> src/vm.rs:423:27
|
423 | let uv1 = self.next_8_bits() as i32;
| ^^^^^^^^^^^^^^^^^^^^^^^^^ help: try: `i32::from(self.next_8_bits())`
|
= note: #[warn(clippy::cast_lossless)] on by default
= help: for further information visit https://rust-lang-nursery.github.io/rust-clippy/v0.0.212/index.html#cast_lossless
结束
我在 w 函数中允许存在未使用的代码，因为我们稍后将会使用它，以及其中一个测试函数。如果您想查看经过 Clippy 审核的版本，请查看：https://gitlab.com/subnetzero/iridium/commit/6206685d402651f0dd0f98b034011fef3990bff6
直到第 31 部分！
原文出处：https://blog.subnetzero.io/post/building-language-vm-part-30/
作者名：Fletcher
专有名词及注释
rustfmt是一个 Rust 语言的代码格式化工具，它能够自动地重新格式化 Rust 代码，以保持代码风格的一致性。rustfmt的目的是减少代码风格上的争论，并使得代码库中的所有代码看起来像是同一个人编写的。它是一个命令行工具，可以单独运行，也可以集成到编辑器或 IDE 中。Clippy是一个 Rust 语言的静态分析工具，它专注于发现常见的编程错误、性能问题和代码风格问题。Clippy提供了一系列的检查器（linter），这些检查器会分析 Rust 代码并提出改进建议。Clippy的目标是帮助开发者写出更清晰、更安全、更高效的 Rust 代码。Clippy通常与rustfmt结合使用，以确保代码不仅在格式上符合标准，而且在内容上也遵循最佳实践。使用这两个工具可以帮助提高代码质量，并减少潜在的问题。