rust: Use the DisplayBytes trait in config printing

This is similar to `std::fmt::Display`, but for arbitrary bytes instead
of Unicode. Writing to an abstract output stream helps avoid allocating
intermediate `Vec<u8>` buffers.

Differential Revision: https://phab.mercurial-scm.org/D9966

rust/Cargo.lock

@@ -244,16 +244,16 b' dependencies = ['
 
 [[package]]
 name = "format-bytes"
-version = "0.1.3"
+version = "0.2.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 dependencies = [
- "format-bytes-macros 0.1.2 (registry+https://github.com/rust-lang/crates.io-index)",
+ "format-bytes-macros 0.3.0 (registry+https://github.com/rust-lang/crates.io-index)",
  "proc-macro-hack 0.5.19 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
 
 [[package]]
 name = "format-bytes-macros"
-version = "0.1.2"
+version = "0.3.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 dependencies = [
  "proc-macro-hack 0.5.19 (registry+https://github.com/rust-lang/crates.io-index)",
@@ -305,7 +305,7 b' dependencies = ['
  "crossbeam-channel 0.4.4 (registry+https://github.com/rust-lang/crates.io-index)",
  "derive_more 0.99.11 (registry+https://github.com/rust-lang/crates.io-index)",
  "flate2 1.0.19 (registry+https://github.com/rust-lang/crates.io-index)",
- "format-bytes 0.1.3 (registry+https://github.com/rust-lang/crates.io-index)",
+ "format-bytes 0.2.0 (registry+https://github.com/rust-lang/crates.io-index)",
  "home 0.5.3 (registry+https://github.com/rust-lang/crates.io-index)",
  "im-rc 15.0.0 (registry+https://github.com/rust-lang/crates.io-index)",
  "lazy_static 1.4.0 (registry+https://github.com/rust-lang/crates.io-index)",
@@ -718,7 +718,7 b' dependencies = ['
  "clap 2.33.3 (registry+https://github.com/rust-lang/crates.io-index)",
  "derive_more 0.99.11 (registry+https://github.com/rust-lang/crates.io-index)",
  "env_logger 0.7.1 (registry+https://github.com/rust-lang/crates.io-index)",
- "format-bytes 0.1.3 (registry+https://github.com/rust-lang/crates.io-index)",
+ "format-bytes 0.2.0 (registry+https://github.com/rust-lang/crates.io-index)",
  "hg-core 0.1.0",
  "log 0.4.11 (registry+https://github.com/rust-lang/crates.io-index)",
  "micro-timer 0.3.1 (registry+https://github.com/rust-lang/crates.io-index)",
@@ -965,8 +965,8 b' dependencies = ['
 "checksum either 1.6.1 (registry+https://github.com/rust-lang/crates.io-index)" = "e78d4f1cc4ae33bbfc157ed5d5a5ef3bc29227303d595861deb238fcec4e9457"
 "checksum env_logger 0.7.1 (registry+https://github.com/rust-lang/crates.io-index)" = "44533bbbb3bb3c1fa17d9f2e4e38bbbaf8396ba82193c4cb1b6445d711445d36"
 "checksum flate2 1.0.19 (registry+https://github.com/rust-lang/crates.io-index)" = "7411863d55df97a419aa64cb4d2f167103ea9d767e2c54a1868b7ac3f6b47129"
-"checksum format-bytes 0.1.3 (registry+https://github.com/rust-lang/crates.io-index)" = "1a7374eb574cd29ae45878554298091c554c3286a17b3afa440a3e2710ae0790"
-"checksum format-bytes-macros 0.1.2 (registry+https://github.com/rust-lang/crates.io-index)" = "4edcc04201cea17a0e6b937adebd46b93fba09924c7e6ed8c515a35ce8432cbc"
+"checksum format-bytes 0.2.0 (registry+https://github.com/rust-lang/crates.io-index)" = "cc35f5e45d6b31053cea13078ffc6fa52fa8617aa54b7ac2011720d9c009e04f"
+"checksum format-bytes-macros 0.3.0 (registry+https://github.com/rust-lang/crates.io-index)" = "b05089e341a0460449e2210c3bf7b61597860b07f0deae58da38dbed0a4c6b6d"
 "checksum fuchsia-cprng 0.1.1 (registry+https://github.com/rust-lang/crates.io-index)" = "a06f77d526c1a601b7c4cdd98f54b5eaabffc14d5f2f0296febdc7f357c6d3ba"
 "checksum gcc 0.3.55 (registry+https://github.com/rust-lang/crates.io-index)" = "8f5f3913fa0bfe7ee1fd8248b6b9f42a5af4b9d65ec2dd2c3c26132b950ecfc2"
 "checksum getrandom 0.1.15 (registry+https://github.com/rust-lang/crates.io-index)" = "fc587bc0ec293155d5bfa6b9891ec18a1e330c234f896ea47fbada4cadbe47e6"

rust/hg-core/Cargo.toml

@@ -29,7 +29,7 b' log = "0.4.8"'
 memmap = "0.7.0"
 zstd = "0.5.3"
 rust-crypto = "0.2.36"
-format-bytes = "0.1.2"
+format-bytes = "0.2.0"
 
 # We don't use the `miniz-oxide` backend to not change rhg benchmarks and until
 # we have a clearer view of which backend is the fastest.

rust/hg-core/src/config/config.rs

@@ -12,6 +12,7 b' use crate::config::layer::{'
     ConfigError, ConfigLayer, ConfigParseError, ConfigValue,
 };
 use crate::utils::files::get_bytes_from_path;
+use format_bytes::{write_bytes, DisplayBytes};
 use std::env;
 use std::path::{Path, PathBuf};
 
@@ -23,13 +24,22 b' pub struct Config {'
     layers: Vec<layer::ConfigLayer>,
 }
 
-impl std::fmt::Debug for Config {
-    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+impl DisplayBytes for Config {
+    fn display_bytes(
+        &self,
+        out: &mut dyn std::io::Write,
+    ) -> std::io::Result<()> {
         for (index, layer) in self.layers.iter().rev().enumerate() {
-            write!(
-                f,
-                "==== Layer {} (trusted: {}) ====\n{:?}",
-                index, layer.trusted, layer
+            write_bytes!(
+                out,
+                b"==== Layer {} (trusted: {}) ====\n{}",
+                index,
+                if layer.trusted {
+                    &b"yes"[..]
+                } else {
+                    &b"no"[..]
+                },
+                layer
             )?;
         }
         Ok(())

rust/hg-core/src/config/layer.rs

@@ -9,7 +9,7 b''
 
 use crate::errors::{HgError, IoResultExt};
 use crate::utils::files::{get_bytes_from_path, get_path_from_bytes};
-use format_bytes::format_bytes;
+use format_bytes::{write_bytes, DisplayBytes};
 use lazy_static::lazy_static;
 use regex::bytes::Regex;
 use std::collections::HashMap;
@@ -165,8 +165,11 b' impl ConfigLayer {'
     }
 }
 
-impl std::fmt::Debug for ConfigLayer {
-    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+impl DisplayBytes for ConfigLayer {
+    fn display_bytes(
+        &self,
+        out: &mut dyn std::io::Write,
+    ) -> std::io::Result<()> {
         let mut sections: Vec<_> = self.sections.iter().collect();
         sections.sort_by(|e0, e1| e0.0.cmp(e1.0));
 
@@ -175,16 +178,13 b' impl std::fmt::Debug for ConfigLayer {'
             items.sort_by(|e0, e1| e0.0.cmp(e1.0));
 
             for (item, config_entry) in items {
-                writeln!(
-                    f,
-                    "{}",
-                    String::from_utf8_lossy(&format_bytes!(
-                        b"{}.{}={} # {}",
-                        section,
-                        item,
-                        &config_entry.bytes,
-                        &self.origin.to_bytes(),
-                    ))
+                write_bytes!(
+                    out,
+                    b"{}.{}={} # {}\n",
+                    section,
+                    item,
+                    &config_entry.bytes,
+                    &self.origin,
                 )?
             }
         }
@@ -224,13 +224,15 b' pub enum ConfigOrigin {'
      * Others? */
 }
 
-impl ConfigOrigin {
-    /// TODO use some kind of dedicated trait?
-    pub fn to_bytes(&self) -> Vec<u8> {
+impl DisplayBytes for ConfigOrigin {
+    fn display_bytes(
+        &self,
+        out: &mut dyn std::io::Write,
+    ) -> std::io::Result<()> {
         match self {
-            ConfigOrigin::File(p) => get_bytes_from_path(p),
-            ConfigOrigin::CommandLine => b"--config".to_vec(),
-            ConfigOrigin::Environment(e) => format_bytes!(b"${}", e),
+            ConfigOrigin::File(p) => out.write_all(&get_bytes_from_path(p)),
+            ConfigOrigin::CommandLine => out.write_all(b"--config"),
+            ConfigOrigin::Environment(e) => write_bytes!(out, b"${}", e),
         }
     }
 }

rust/rhg/Cargo.toml

@@ -14,4 +14,4 b' derive_more = "0.99"'
 log = "0.4.11"
 micro-timer = "0.3.1"
 env_logger = "0.7.1"
-format-bytes = "0.1.3"
+format-bytes = "0.2.0"

rust/rhg/src/error.rs

@@ -90,7 +90,7 b' impl From<ConfigParseError> for CommandE'
         CommandError::Abort {
             message: format_bytes!(
                 b"config parse error in {}{}: '{}'",
-                origin.to_bytes(),
+                origin,
                 line_message,
                 bytes
             ),