cache taps

There are plenty of IO operations inside Tap object, and it will be more
when implementing formula alias reverse look up(e.g. list all of alias
names for a formula). So let's cache them.

Some benchmark:

$ time brew info $(brew ruby -e 'puts Formula.tap_names') > /dev/null
Before: 6.40s user 2.42s system 96% cpu 9.134 total
After: 4.75s user 0.77s system 97% cpu 5.637 total

Closes Homebrew/homebrew#44377.

Signed-off-by: Xu Cheng <xucheng@me.com>

9 files changed, 13 insertions, 11 deletions

diff --git a/Library/Homebrew/cmd/info.rb b/Library/Homebrew/cmd/info.rb
index a2b491e05..52d39ca15 100644
--- a/Library/Homebrew/cmd/info.rb
+++ b/Library/Homebrew/cmd/info.rb
@@ -69,7 +69,7 @@ module Homebrew
   def github_info(f)
     if f.tap?
       user, repo = f.tap.split("/", 2)
-      tap = Tap.new user, repo.gsub(/^homebrew-/, "")
+      tap = Tap.fetch user, repo.gsub(/^homebrew-/, "")
       if remote = tap.remote
         path = f.path.relative_path_from(tap.path)
         github_remote_path(remote, path)
diff --git a/Library/Homebrew/cmd/readall.rb b/Library/Homebrew/cmd/readall.rb
index 81eaba37d..5e87fcbdb 100644
--- a/Library/Homebrew/cmd/readall.rb
+++ b/Library/Homebrew/cmd/readall.rb
@@ -46,7 +46,7 @@ module Homebrew
     if ARGV.named.empty?
       formulae = Formula.files
     else
-      tap = Tap.new(*tap_args)
+      tap = Tap.fetch(*tap_args)
       raise TapUnavailableError, tap.name unless tap.installed?
       formulae = tap.formula_files
     end
diff --git a/Library/Homebrew/cmd/tap-info.rb b/Library/Homebrew/cmd/tap-info.rb
index 1354264df..dc979af7e 100644
--- a/Library/Homebrew/cmd/tap-info.rb
+++ b/Library/Homebrew/cmd/tap-info.rb
@@ -6,7 +6,7 @@ module Homebrew
       taps = Tap
     else
       taps = ARGV.named.map do |name|
-        Tap.new(*tap_args(name))
+        Tap.fetch(*tap_args(name))
       end
     end
 
diff --git a/Library/Homebrew/cmd/tap-pin.rb b/Library/Homebrew/cmd/tap-pin.rb
index 40888428a..80f1f762a 100644
--- a/Library/Homebrew/cmd/tap-pin.rb
+++ b/Library/Homebrew/cmd/tap-pin.rb
@@ -3,7 +3,7 @@ require "cmd/tap"
 module Homebrew
   def tap_pin
     ARGV.named.each do |name|
-      tap = Tap.new(*tap_args(name))
+      tap = Tap.fetch(*tap_args(name))
       tap.pin
       ohai "Pinned #{tap.name}"
     end
diff --git a/Library/Homebrew/cmd/tap-unpin.rb b/Library/Homebrew/cmd/tap-unpin.rb
index 4462ce68d..641b7c945 100644
--- a/Library/Homebrew/cmd/tap-unpin.rb
+++ b/Library/Homebrew/cmd/tap-unpin.rb
@@ -3,7 +3,7 @@ require "cmd/tap"
 module Homebrew
   def tap_unpin
     ARGV.named.each do |name|
-      tap = Tap.new(*tap_args(name))
+      tap = Tap.fetch(*tap_args(name))
       tap.unpin
       ohai "Unpinned #{tap.name}"
     end
diff --git a/Library/Homebrew/cmd/tap.rb b/Library/Homebrew/cmd/tap.rb
index 291407aff..294106b3c 100644
--- a/Library/Homebrew/cmd/tap.rb
+++ b/Library/Homebrew/cmd/tap.rb
@@ -23,7 +23,7 @@ module Homebrew
     # ensure git is installed
     Utils.ensure_git_installed!
 
-    tap = Tap.new user, repo
+    tap = Tap.fetch user, repo
     return false if tap.installed?
     ohai "Tapping #{tap}"
     remote = clone_target || "https://github.com/#{tap.user}/homebrew-#{tap.repo}"
diff --git a/Library/Homebrew/cmd/test-bot.rb b/Library/Homebrew/cmd/test-bot.rb
index 66f23d873..658f042f9 100644
--- a/Library/Homebrew/cmd/test-bot.rb
+++ b/Library/Homebrew/cmd/test-bot.rb
@@ -39,20 +39,20 @@ module Homebrew
 
   def resolve_test_tap
     tap = ARGV.value("tap")
-    return Tap.new(*tap_args(tap)) if tap
+    return Tap.fetch(*tap_args(tap)) if tap
 
     if ENV["UPSTREAM_BOT_PARAMS"]
       bot_argv = ENV["UPSTREAM_BOT_PARAMS"].split " "
       bot_argv.extend HomebrewArgvExtension
       tap = bot_argv.value("tap")
-      return Tap.new(*tap_args(tap)) if tap
+      return Tap.fetch(*tap_args(tap)) if tap
     end
 
     if git_url = ENV["UPSTREAM_GIT_URL"] || ENV["GIT_URL"]
       # Also can get tap from Jenkins GIT_URL.
       url_path = git_url.sub(%r{^https?://github\.com/}, "").chomp("/")
       HOMEBREW_TAP_ARGS_REGEX =~ url_path
-      return Tap.new($1, $3) if $1 && $3 && $3 != "homebrew"
+      return Tap.fetch($1, $3) if $1 && $3 && $3 != "homebrew"
     end
 
     # return nil means we are testing core repo.
diff --git a/Library/Homebrew/cmd/untap.rb b/Library/Homebrew/cmd/untap.rb
index 22dab7383..c70a0d007 100644
--- a/Library/Homebrew/cmd/untap.rb
+++ b/Library/Homebrew/cmd/untap.rb
@@ -6,7 +6,7 @@ module Homebrew
     raise "Usage is `brew untap <tap-name>`" if ARGV.empty?
 
     ARGV.named.each do |tapname|
-      tap = Tap.new(*tap_args(tapname))
+      tap = Tap.fetch(*tap_args(tapname))
 
       raise TapUnavailableError, tap.name unless tap.installed?
       puts "Untapping #{tap}... (#{tap.path.abv})"
diff --git a/Library/Homebrew/cmd/update.rb b/Library/Homebrew/cmd/update.rb
index 917244a8d..b50348bcf 100644
--- a/Library/Homebrew/cmd/update.rb
+++ b/Library/Homebrew/cmd/update.rb
@@ -63,6 +63,8 @@ module Homebrew
       end
     end
 
+    Tap.clear_cache
+
     # automatically tap any migrated formulae's new tap
     report.select_formula(:D).each do |f|
       next unless (dir = HOMEBREW_CELLAR/f).exist?
@@ -372,7 +374,7 @@ class Report
         user = $1
         repo = $2.sub("homebrew-", "")
         oldname = path.basename(".rb").to_s
-        next unless newname = Tap.new(user, repo).formula_renames[oldname]
+        next unless newname = Tap.fetch(user, repo).formula_renames[oldname]
       else
         oldname = path.basename(".rb").to_s
         next unless newname = FORMULA_RENAMES[oldname]