perf(init): cache the LocalHostName lookup (#14066)

Signed-off-by: 付典 <fudianchn@gmail.com>

lib/cli.zsh

@@ -739,8 +739,8 @@ function _omz::reload {
   # Old zsh versions don't have ZSH_ARGZERO
   local zsh="${ZSH_ARGZERO:-${functrace[-1]%:*}}"
   # ZSH_ARGZERO is how zsh was invoked, not the path to it, so re-resolve
-  # anything that is not absolute (see #13919)
-  [[ "${zsh#-}" != /* ]] && (( $+commands[zsh] )) && zsh="$commands[zsh]"
+  # anything that is not absolute via $PATH at exec time (see #13919)
+  [[ "${zsh#-}" != /* ]] && (( $+commands[zsh] )) && zsh="zsh"
   # Check whether to run a login shell
   [[ "$zsh" = -* || -o login ]] && exec -l "${zsh#-}" || exec "$zsh"
 }
@@ -923,8 +923,8 @@ function _omz::update {
     # Old zsh versions don't have ZSH_ARGZERO
     local zsh="${ZSH_ARGZERO:-${functrace[-1]%:*}}"
     # ZSH_ARGZERO is how zsh was invoked, not the path to it, so re-resolve
-    # anything that is not absolute (see #13919)
-    [[ "${zsh#-}" != /* ]] && (( $+commands[zsh] )) && zsh="$commands[zsh]"
+    # anything that is not absolute via $PATH at exec time (see #13919)
+    [[ "${zsh#-}" != /* ]] && (( $+commands[zsh] )) && zsh="zsh"
     # Check whether to run a login shell
     [[ "$zsh" = -* || -o login ]] && exec -l "${zsh#-}" || exec "$zsh"
   fi

lib/theme-and-appearance.zsh

@@ -13,69 +13,92 @@ ZSH_THEME_RUBY_PROMPT_PREFIX="("
 ZSH_THEME_RUBY_PROMPT_SUFFIX=")"
 
 
+# The command probes below fork a process each, and their result doesn't change
+# from one shell to the next, so they're cached for a day (like lib/grep.zsh).
+typeset -A __omz_probes
+__omz_probe_cache="$ZSH_CACHE_DIR/appearance-probes"
+__omz_probe_cached=("$__omz_probe_cache"(Nm-1))
+[[ -z "$__omz_probe_cached" ]] || source "$__omz_probe_cache"
+
+function __omz_test_cmd_args {
+  # Usage: __omz_test_cmd_args cmd args...
+  # Runs `cmd args... /dev/null` and remembers whether it succeeded, so a
+  # command needing two operands passes the first one itself:
+  # e.g. __omz_test_cmd_args gls --color  ->  gls --color /dev/null
+  #      __omz_test_cmd_args diff --color /dev/null  ->  diff --color /dev/null /dev/null
+  local key="$*"
+  if (( ! ${+__omz_probes[$key]} )); then
+    command "$@" /dev/null &>/dev/null
+    __omz_probes[$key]=$?
+    if [[ -w "$ZSH_CACHE_DIR" ]]; then
+      print -r -- "__omz_probes=(" "${(@qqkv)__omz_probes}" ")" >| "$__omz_probe_cache"
+    fi
+  fi
+  return $__omz_probes[$key]
+}
+
 # Use diff --color if available
-if command diff --color /dev/null{,} &>/dev/null; then
+if __omz_test_cmd_args diff --color /dev/null; then
   function diff {
     command diff --color "$@"
   }
 fi
 
-# Don't set ls coloring if disabled
-[[ "$DISABLE_LS_COLORS" != true ]] || return 0
+# Set up ls coloring. Done in a function so the early return below still
+# reaches the cleanup at the end of this file.
+() {
+  # Don't set ls coloring if disabled
+  [[ "$DISABLE_LS_COLORS" != true ]] || return 0
 
-# Default coloring for BSD-based ls
-export LSCOLORS="Gxfxcxdxbxegedabagacad"
+  # Default coloring for BSD-based ls
+  export LSCOLORS="Gxfxcxdxbxegedabagacad"
 
-# Default coloring for GNU-based ls
-if [[ -z "$LS_COLORS" ]]; then
-  # Define LS_COLORS via dircolors if available. Otherwise, set a default
-  # equivalent to LSCOLORS (generated via https://geoff.greer.fm/lscolors)
-  if (( $+commands[dircolors] )); then
-    [[ -f "$HOME/.dircolors" ]] \
-      && source <(dircolors -b "$HOME/.dircolors") \
-      || source <(dircolors -b)
-  else
-    export LS_COLORS="di=1;36:ln=35:so=32:pi=33:ex=31:bd=34;46:cd=34;43:su=30;41:sg=30;46:tw=30;42:ow=30;43"
+  # Default coloring for GNU-based ls
+  if [[ -z "$LS_COLORS" ]]; then
+    # Define LS_COLORS via dircolors if available. Otherwise, set a default
+    # equivalent to LSCOLORS (generated via https://geoff.greer.fm/lscolors)
+    if (( $+commands[dircolors] )); then
+      [[ -f "$HOME/.dircolors" ]] \
+        && source <(dircolors -b "$HOME/.dircolors") \
+        || source <(dircolors -b)
+    else
+      export LS_COLORS="di=1;36:ln=35:so=32:pi=33:ex=31:bd=34;46:cd=34;43:su=30;41:sg=30;46:tw=30;42:ow=30;43"
+    fi
   fi
-fi
 
-function test-ls-args {
-  # Usage: test-ls-args cmd args...
-  # e.g. test-ls-args gls --color
-  command "$@" /dev/null &>/dev/null
+  # Find the option for using colors in ls, depending on the version
+  case "$OSTYPE" in
+    netbsd*)
+      # On NetBSD, test if `gls` (GNU ls) is installed (this one supports colors);
+      # otherwise, leave ls as is, because NetBSD's ls doesn't support -G
+      __omz_test_cmd_args gls --color && alias ls='gls --color=tty'
+      ;;
+    openbsd*)
+      # On OpenBSD, `gls` (ls from GNU coreutils) and `colorls` (ls from base,
+      # with color and multibyte support) are available from ports.
+      # `colorls` will be installed on purpose and can't be pulled in by installing
+      # coreutils (which might be installed for ), so prefer it to `gls`.
+      __omz_test_cmd_args gls --color && alias ls='gls --color=tty'
+      __omz_test_cmd_args colorls -G && alias ls='colorls -G'
+      ;;
+    (darwin|freebsd)*)
+      # This alias works by default just using $LSCOLORS
+      __omz_test_cmd_args ls -G && alias ls='ls -G'
+      # Only use GNU ls if installed and there are user defaults for $LS_COLORS,
+      # as the default coloring scheme is not very pretty
+      zstyle -t ':omz:lib:theme-and-appearance' gnu-ls \
+        && __omz_test_cmd_args gls --color \
+        && alias ls='gls --color=tty'
+      ;;
+    *)
+      if __omz_test_cmd_args ls --color; then
+        alias ls='ls --color=tty'
+      elif __omz_test_cmd_args ls -G; then
+        alias ls='ls -G'
+      fi
+      ;;
+  esac
 }
 
-# Find the option for using colors in ls, depending on the version
-case "$OSTYPE" in
-  netbsd*)
-    # On NetBSD, test if `gls` (GNU ls) is installed (this one supports colors);
-    # otherwise, leave ls as is, because NetBSD's ls doesn't support -G
-    test-ls-args gls --color && alias ls='gls --color=tty'
-    ;;
-  openbsd*)
-    # On OpenBSD, `gls` (ls from GNU coreutils) and `colorls` (ls from base,
-    # with color and multibyte support) are available from ports.
-    # `colorls` will be installed on purpose and can't be pulled in by installing
-    # coreutils (which might be installed for ), so prefer it to `gls`.
-    test-ls-args gls --color && alias ls='gls --color=tty'
-    test-ls-args colorls -G && alias ls='colorls -G'
-    ;;
-  (darwin|freebsd)*)
-    # This alias works by default just using $LSCOLORS
-    test-ls-args ls -G && alias ls='ls -G'
-    # Only use GNU ls if installed and there are user defaults for $LS_COLORS,
-    # as the default coloring scheme is not very pretty
-    zstyle -t ':omz:lib:theme-and-appearance' gnu-ls \
-      && test-ls-args gls --color \
-      && alias ls='gls --color=tty'
-    ;;
-  *)
-    if test-ls-args ls --color; then
-      alias ls='ls --color=tty'
-    elif test-ls-args ls -G; then
-      alias ls='ls -G'
-    fi
-    ;;
-esac
-
-unfunction test-ls-args
+unfunction __omz_test_cmd_args
+unset __omz_probes __omz_probe_cache __omz_probe_cached

oh-my-zsh.sh

@@ -100,7 +100,28 @@ done
 # Figure out the SHORT hostname
 if [[ "$OSTYPE" = darwin* ]]; then
   # macOS's $HOST changes with dhcp, etc. Use LocalHostName if possible.
-  SHORT_HOST=$(scutil --get LocalHostName 2>/dev/null) || SHORT_HOST="${HOST/.*/}"
+  # scutil costs a fork on every start, so remember its answer for a day
+  # (like lib/grep.zsh) and re-check sooner if $HOST changes.
+  __omz_host_cache="$ZSH_CACHE_DIR/localhostname"
+  __omz_host_cached=("$__omz_host_cache"(Nm-1))
+  __omz_host_key=
+  SHORT_HOST=
+  if [[ -n "$__omz_host_cached" ]]; then
+    if ! { read -r __omz_host_key && read -r SHORT_HOST } < "$__omz_host_cache"; then
+      __omz_host_key=
+      SHORT_HOST=
+    fi
+  fi
+  if [[ "$__omz_host_key" != "$HOST" || -z "$SHORT_HOST" ]]; then
+    # only cache what scutil actually answered, so a transient failure
+    # doesn't pin the fallback name for a day
+    if SHORT_HOST=$(scutil --get LocalHostName 2>/dev/null) && [[ -n "$SHORT_HOST" ]]; then
+      [[ ! -w "$ZSH_CACHE_DIR" ]] || print -rl -- "$HOST" "$SHORT_HOST" >| "$__omz_host_cache"
+    else
+      SHORT_HOST="${HOST/.*/}"
+    fi
+  fi
+  unset __omz_host_cache __omz_host_cached __omz_host_key
 else
   SHORT_HOST="${HOST/.*/}"
 fi