[rubygems/rubygems] Aggressively optimize allocations in SafeMarshal

Reduces allocations in a bundle install --full-index by an order of magnitude

Main wins are (a) getting rid of exessive string allocations for exception message stack

(b) Avoiding hash allocations caused by kwargs for #initialize

(c) avoid using unpack to do bit math, its easy enough to do by hand

(d) special case the most common elements so they can be read without an allocation

(e) avoid string allocations every time a symbol->string lookup is done by using symbol#name

https://github.com/rubygems/rubygems/commit/7d2ee51402

1 files changed, 29 insertions, 1 deletions

diff --git a/test/rubygems/test_gem_safe_marshal.rb b/test/rubygems/test_gem_safe_marshal.rb
index d123ad5dc4..5c73170192 100644
--- a/test/rubygems/test_gem_safe_marshal.rb
+++ b/test/rubygems/test_gem_safe_marshal.rb
@@ -17,7 +17,9 @@ class TestGemSafeMarshal < Gem::TestCase
   define_method("test_safe_load_marshal Float 30000000.0") { assert_safe_load_marshal "\x04\bf\b3e7" }
   define_method("test_safe_load_marshal Float -30000000.0") { assert_safe_load_marshal "\x04\bf\t-3e7" }
   define_method("test_safe_load_marshal Gem::Version #<Gem::Version \"1.abc\">") { assert_safe_load_marshal "\x04\bU:\x11Gem::Version[\x06I\"\n1.abc\x06:\x06ET" }
-  define_method("test_safe_load_marshal Hash {}") { assert_safe_load_marshal "\x04\b}\x00[\x00" }
+  define_method("test_safe_load_marshal Hash {} default value") { assert_safe_load_marshal "\x04\b}\x00[\x00", additional_methods: [:default] }
+  define_method("test_safe_load_marshal Hash {}") { assert_safe_load_marshal "\x04\b{\x00" }
+  define_method("test_safe_load_marshal Array {}") { assert_safe_load_marshal "\x04\b[\x00" }
   define_method("test_safe_load_marshal Hash {:runtime=>:development}") { assert_safe_load_marshal "\x04\bI{\x06:\fruntime:\x10development\x06:\n@type[\x00", permitted_ivars: { "Hash" => %w[@type] } }
   define_method("test_safe_load_marshal Integer -1") { assert_safe_load_marshal "\x04\bi\xFA" }
   define_method("test_safe_load_marshal Integer -1048575") { assert_safe_load_marshal "\x04\bi\xFD\x01\x00\xF0" }
@@ -124,6 +126,12 @@ class TestGemSafeMarshal < Gem::TestCase
     assert_safe_load_as [:development, :development]
   end
 
+  def test_length_one_symbols
+    with_const(Gem::SafeMarshal, :PERMITTED_SYMBOLS, %w[E A b 0] << "") do
+      assert_safe_load_as [:A, :E, :E, :A, "".to_sym, "".to_sym], additional_methods: [:instance_variables]
+    end
+  end
+
   def test_repeated_string
     s = "hello"
     a = [s]
@@ -156,6 +164,12 @@ class TestGemSafeMarshal < Gem::TestCase
       String.new("abc", encoding: "Windows-1256"),
       String.new("abc", encoding: Encoding::BINARY),
       String.new("abc", encoding: "UTF-32"),
+
+      String.new("", encoding: "US-ASCII"),
+      String.new("", encoding: "UTF-8"),
+      String.new("", encoding: "Windows-1256"),
+      String.new("", encoding: Encoding::BINARY),
+      String.new("", encoding: "UTF-32"),
     ].each do |s|
       assert_safe_load_as s, additional_methods: [:encoding]
       assert_safe_load_as [s, s], additional_methods: [->(a) { a.map(&:encoding) }]
@@ -282,6 +296,20 @@ class TestGemSafeMarshal < Gem::TestCase
     assert_equal e.message, "Attempting to load unpermitted symbol \"rspec\" @ root.[9].[0].@name"
   end
 
+  def test_gem_spec_disallowed_ivar
+    e = assert_raise(Gem::SafeMarshal::Visitors::ToRuby::UnpermittedIvarError) do
+      spec = Gem::Specification.new do |s|
+        s.name = "hi"
+        s.version = "1.2.3"
+
+        s.dependencies << Gem::Dependency.new("rspec", Gem::Requirement.new([">= 1.2.3"]), :runtime).tap {|d| d.instance_variable_set(:@foobar, "rspec") }
+      end
+      Gem::SafeMarshal.safe_load(Marshal.dump(spec))
+    end
+
+    assert_equal e.message, "Attempting to set unpermitted ivar \"@foobar\" on object of class Gem::Dependency @ root.[9].[0].ivar_5"
+  end
+
   def assert_safe_load_marshal(dumped, additional_methods: [], permitted_ivars: nil, equality: true, marshal_dump_equality: true)
     loaded = Marshal.load(dumped)
     safe_loaded =