Contents in Detail. Who This Book Is For... xx Using Ruby to Test Itself... xx Which Implementation of Ruby?... xxi Overview...

Transcription

1 Contents in Detail Foreword by Aaron Patterson xv Acknowledgments xvii Introduction Who This Book Is For xx Using Ruby to Test Itself.... xx Which Implementation of Ruby?.... xxi Overview... xxi 1 Tokenization and Parsing 3 Tokens: The Words That Make Up the Ruby Language... 4 The parser_yylex Function... 8 Experiment 1-1: Using Ripper to Tokenize Different Ruby Scripts... 9 Parsing: How Ruby Understands Your Code Understanding the LALR Parse Algorithm Some Actual Ruby Grammar Rules Reading a Bison Grammar Rule Experiment 1-2: Using Ripper to Parse Different Ruby Scripts Summary Compilation 31 No Compiler for Ruby Ruby 1.9 and 2.0 Introduce a Compiler How Ruby Compiles a Simple Script Compiling a Call to a Block How Ruby Iterates Through the AST Experiment 2-1: Displaying YARV Instructions The Local Table Compiling Optional Arguments Compiling Keyword Arguments Experiment 2-2: Displaying the Local Table Summary How Ruby Executes Your Code 55 YARV s Internal Stack and Your Ruby Stack Stepping Through How Ruby Executes a Simple Script Executing a Call to a Block Taking a Close Look at a YARV Instruction Experiment 3-1: Benchmarking Ruby 2.0 and Ruby 1.9 vs. Ruby xix

2 Local and Dynamic Access of Ruby Variables Local Variable Access Method Arguments Are Treated Like Local Variables Dynamic Variable Access Climbing the Environment Pointer Ladder in C Experiment 3-2: Exploring Special Variables A Definitive List of Special Variables Summary Control Structures and Method Dispatch 83 How Ruby Executes an if Statement Jumping from One Scope to Another Catch Tables Other Uses for Catch Tables Experiment 4-1: Testing How Ruby Implements for Loops Internally The send Instruction: Ruby s Most Complex Control Structure Method Lookup and Method Dispatch Eleven Types of Ruby Methods Calling Normal Ruby Methods Preparing Arguments for Normal Ruby Methods Calling Built-In Ruby Methods Calling attr_reader and attr_writer Method Dispatch Optimizes attr_reader and attr_writer Experiment 4-2: Exploring How Ruby Implements Keyword Arguments Summary Objects and Classes 105 Inside a Ruby Object Inspecting klass and ivptr Visualizing Two Instances of One Class Generic Objects Simple Ruby Values Don t Require a Structure at All Do Generic Objects Have Instance Variables? Reading the RBasic and RObject C Structure Definitions Where Does Ruby Save Instance Variables for Generic Objects? Experiment 5-1: How Long Does It Take to Save a New Instance Variable? What s Inside the RClass Structure? Inheritance Class Instance Variables vs. Class Variables Getting and Setting Class Variables Constants The Actual RClass Structure Reading the RClass C Structure Definition Experiment 5-2: Where Does Ruby Save Class Methods? Summary x Contents in Detail

3 6 Method Lookup and Constant Lookup 133 How Ruby Implements Modules Modules Are Classes Including a Module into a Class Ruby s Method Lookup Algorithm A Method Lookup Example The Method Lookup Algorithm in Action Multiple Inheritance in Ruby The Global Method Cache The Inline Method Cache Clearing Ruby s Method Caches Including Two Modules into One Class Including One Module into Another A Module#prepend Example How Ruby Implements Module#prepend Experiment 6-1: Modifying a Module After Including It Classes See Methods Added to a Module Later Classes Don t See Submodules Included Later Included Classes Share the Method Table with the Original Module A Close Look at How Ruby Copies Modules Constant Lookup Finding a Constant in a Superclass How Does Ruby Find a Constant in the Parent Namespace? Lexical Scope in Ruby Creating a Constant for a New Class or Module Finding a Constant in the Parent Namespace Using Lexical Scope Ruby s Constant Lookup Algorithm Experiment 6-2: Which Constant Will Ruby Find First? Ruby s Actual Constant Lookup Algorithm Summary The Hash Table: The Workhorse of Ruby Internals 167 Hash Tables in Ruby Saving a Value in a Hash Table Retrieving a Value from a Hash Table Experiment 7-1: Retrieving a Value from Hashes of Varying Sizes How Hash Tables Expand to Accommodate More Values Hash Collisions Rehashing Entries How Does Ruby Rehash Entries in a Hash Table? Experiment 7-2: Inserting One New Element into Hashes of Varying Sizes Where Do the Magic Numbers 57 and 67 Come From? How Ruby Implements Hash Functions Experiment 7-3: Using Objects as Keys in a Hash Hash Optimization in Ruby Summary Contents in Detail xi

4 8 How Ruby Borrowed a Decades-Old Idea from Lisp 191 Blocks: Closures in Ruby Stepping Through How Ruby Calls a Block Borrowing an Idea from The rb_block_t and rb_control_frame_t Structures Experiment 8-1: Which Is Faster: A while Loop or Passing a Block to each? Lambdas and Procs: Treating a Function as a First-Class Citizen Stack vs. Heap Memory A Closer Look at How Ruby Saves a String Value How Ruby Creates a Lambda How Ruby Calls a Lambda The Proc Object Experiment 8-2: Changing Local Variables After Calling lambda Calling lambda More Than Once in the Same Scope Summary Metaprogramming 219 Alternative Ways to Define Methods Ruby s Normal Method Definition Process Defining Class Methods Using an Object Prefix Defining Class Methods Using a New Lexical Scope Defining Methods Using Singleton Classes Defining Methods Using Singleton Classes in a Lexical Scope Creating Refinements Using Refinements Experiment 9-1: Who Am I? How self Changes with Lexical Scope self in the Top Scope self in a Class Scope self in a Metaclass Scope self Inside a Class Method Metaprogramming and Closures: eval, instance_eval, and binding Code That Writes Code Calling eval with binding An instance_eval Example Another Important Part of Ruby Closures instance_eval Changes self to the Receiver instance_eval Creates a Singleton Class for a New Lexical Scope How Ruby Keeps Track of Lexical Scope for Blocks Experiment 9-2: Using a Closure to Define a Method Using define_method Methods Acting as Closures Summary xii Contents in Detail

5 10 JRuby: Ruby on the JVM 251 Running Programs with MRI and JRuby How JRuby Parses and Compiles Your Code How JRuby Executes Your Code Implementing Ruby Classes with Java Classes Experiment 10-1: Monitoring JRuby s Just-in-Time Compiler Experiment Code Using the -J-XX:+PrintCompilation Option Does JIT Speed Up Your JRuby Program? Strings in JRuby and MRI How JRuby and MRI Save String Data Copy-on-Write Experiment 10-2: Measuring Copy-on-Write Performance Creating a Unique, Nonshared String Experiment Code Visualizing Copy-on-Write Modifying a Shared String Is Slower Summary Rubinius: Ruby Implemented with Ruby 273 The Rubinius Kernel and Virtual Machine Tokenization and Parsing Using Ruby to Compile Ruby Rubinius Bytecode Instructions Ruby and C++ Working Together Implementing Ruby Objects with C++ Objects Experiment 11-1: Comparing Backtraces in MRI and Rubinius Backtraces in Rubinius Arrays in Rubinius and MRI Arrays Inside of MRI The RArray C Structure Definition Arrays Inside of Rubinius Experiment 11-2: Exploring the Rubinius Implementation of Array#shift Reading Array#shift Modifying Array#shift Summary Garbage Collection in MRI, JRuby, and Rubinius 295 Garbage Collectors Solve Three Problems Garbage Collection in MRI: Mark and Sweep The Free List MRI s Use of Multiple Free Lists Marking How Does MRI Mark Live Objects? Contents in Detail xiii

6 Sweeping Lazy Sweeping The RVALUE Structure Disadvantages of Mark and Sweep Experiment 12-1: Seeing MRI Garbage Collection in Action Seeing MRI Perform a Lazy Sweep Seeing MRI Perform a Full Collection Interpreting a GC Profile Report Garbage Collection in JRuby and Rubinius Copying Garbage Collection Bump Allocation The Semi-Space Algorithm The Eden Heap Generational Garbage Collection The Weak Generational Hypothesis Using the Semi-Space Algorithm for Young Objects Promoting Objects Garbage Collection for Mature Objects References Between Generations Concurrent Garbage Collection Marking While the Object Graph Changes Tricolor Marking Three Garbage Collectors in the JVM Experiment 12-2: Using Verbose GC Mode in JRuby Triggering Major Collections Further Reading Summary Index 327 xiv Contents in Detail