Accessors and Views with Lifetime Extension
Total Page:16
File Type:pdf, Size:1020Kb
Load more
Recommended publications
-
CS 403/503: Programming Languages
BNF for <expression> <expression> → identifier | number | CS 403 -<expression> | (<expression>) | <expression><operator><expression> Organization of Programming Languages <operator> → + | - | * | / Class 3 - August 30, 2001 Topics For Today Parse Tree Review of BNF (Chapter 2.1) Derivations and parse trees (Chapter 2.1) Binding time (Chapter 3.1) Object lifetime and storage slope * x + intercept management (Chapter 3.2) BNF Concept Review Another Parse Tree Terminal symbols: Actual items that are part of the language (0,1,+,-,*,/,etc.) Non-Terminal symbols: <expr>, <op>, etc. Rule/production: A single line of BNF Alternatives: Expressed with | Also: slope * x + intercept *: 0 or more occurrences +:1 or more occurrences 1 Binding Lifetimes • Binding lifetime: The period of time Def: A binding is an association, such between the creation and destruction of a as between an attribute and an entity, name-to-object binding • Object lifetime: The period of time or between an operation and a between the creation and destruction of symbol. an object • These don’t necessarily coincide Def: Binding time is the time at which a • EX. Reference parameters binding takes place. Possible binding times Object Lifetimes… 1. Language design time--e.g., bind operator …correspond to one of three principal symbols to operations 2. Language implementation time--e.g., bind fl. pt. storage allocation mechanisms: type to a representation Static objects: Object lifetime = program 3. Compile time--e.g., bind a variable to a type in C execution. Object bound to one storage or Java location from load time on. 4. Load time--e.g., bind a FORTRAN 77 variable to a memory cell (or a C static variable) Stack objects: Object lifetime = subroutine 5. -
System Calls
System Calls What are they? ● Standard interface to allow the kernel to safely handle user requests – Read from hardware – Spawn a new process – Get current time – Create shared memory ● Message passing technique between – OS kernel (server) – User (client) Executing System Calls ● User program issues call ● Core kernel looks up call in syscall table ● Kernel module handles syscall action ● Module returns result of system call ● Core kernel forwards result to user Module is not Loaded... ● User program issues call ● Core kernel looks up call in syscall table ● Kernel module isn't loaded to handle action ● ... ● Where does call go? System Call Wrappers ● Wrapper calls system call if loaded – Otherwise returns an error ● Needs to be in a separate location so that the function can actually be called – Uses function pointer to point to kernel module implementation Adding System Calls ● You'll need to add and implement: – int start_elevator(void); – int issue_request(int, int, int); – int stop_elevator(void); ● As an example, let's add a call to printk an argument passed in: – int test_call(int); Adding System Calls ● Files to add (project files): – /usr/src/test_kernel/hello_world/test_call.c – /usr/src/test_kernel/hello_world/hello.c – /usr/src/test_kernel/hello_world/Makefile ● Files to modify (core kernel): – /usr/src/test_kernel/arch/x86/entry/syscalls/syscall_64.tbl – /usr/src/test_kernel/include/linux/syscalls.h – /usr/src/test_kernel/Makefile hello_world/test_call.c ● #include <linux/linkage.h> ● #include <linux/kernel.h> ● #include -
Programming Project 5: User-Level Processes
Project 5 Operating Systems Programming Project 5: User-Level Processes Due Date: ______________________________ Project Duration: One week Overview and Goal In this project, you will explore user-level processes. You will create a single process, running in its own address space. When this user-level process executes, the CPU will be in “user mode.” The user-level process will make system calls to the kernel, which will cause the CPU to switch into “system mode.” Upon completion, the CPU will switch back to user mode before resuming execution of the user-level process. The user-level process will execute in its own “logical address space.” Its address space will be broken into a number of “pages” and each page will be stored in a frame in memory. The pages will be resident (i.e., stored in frames in physical memory) at all times and will not be swapped out to disk in this project. (Contrast this with “virtual” memory, in which some pages may not be resident in memory.) The kernel will be entirely protected from the user-level program; nothing the user-level program does can crash the kernel. Download New Files The files for this project are available in: http://www.cs.pdx.edu/~harry/Blitz/OSProject/p5/ Please retain your old files from previous projects and don’t modify them once you submit them. You should get the following files: Switch.s Runtime.s System.h System.c Page 1 Project 5 Operating Systems List.h List.c BitMap.h BitMap.c makefile FileStuff.h FileStuff.c Main.h Main.c DISK UserRuntime.s UserSystem.h UserSystem.c MyProgram.h MyProgram.c TestProgram1.h TestProgram1.c TestProgram2.h TestProgram2.c The following files are unchanged from the last project and you should not modify them: Switch.s Runtime.s System.h System.c -- except HEAP_SIZE has been modified List.h List.c BitMap.h BitMap.c The following files are not provided; instead you will modify what you created in the last project. -
C++/CLI Language Specification
Ecma/TC39-TG5/2004/25 C++/CLI Language Specification Working Draft 1.5, Jun, 2004 Public Review Document Text highlighted like this indicates a placeholder for some future action. It might be a note from the editor to himself, or an indication of the actual or expected direction of some as-yet open issue. Note: In the spirit of the "Working Draft, Standard for Programming Language C++", this is an early draft. It’s known to be incomplet and incorrekt, and it has lots of bad formatting. Publication Time: 6/17/2004 11:44 PM Table of Contents Table of Contents Introduction....................................................................................................................................................xi 1. Scope............................................................................................................................................................. 1 2. Conformance ............................................................................................................................................... 2 3. Normative references .................................................................................................................................. 3 4. Definitions .................................................................................................................................................... 4 5. Notational conventions................................................................................................................................ 7 6. Acronyms and abbreviations -
CS 0449: Introduction to Systems Software
CS 0449: Introduction to Systems Software Jonathan Misurda Computer Science Department University of Pittsburgh [email protected] http://www.cs.pitt.edu/∼jmisurda Version 3, revision 1 Last modified: July 27, 2017 at 1:33 P.M. Copyright © 2017 by Jonathan Misurda This text is meant to accompany the course CS 0449 at the University of Pittsburgh. Any other use, commercial or otherwise, is prohibited without permission of the author. All rights reserved. Java is a registered trademark of Oracle Corporation. This reference is dedicated to the students of CS 0449, Fall 2007 (2081). Their patience in dealing with a changing course and feedback on the first version of this text was greatly appreciated. Contents Contents i List of Figures v List of Code Listings vii Preface ix 1 Pointers 1 1.1 Basic Pointers . 2 1.1.1 Fundamental Operations . 2 1.2 Passing Pointers to Functions . 4 1.3 Pointers, Arrays, and Strings . 5 1.3.1 Pointer Arithmetic . 6 1.4 Terms and Definitions . 7 2 Variables: Scope & Lifetime 8 2.1 Scope and Lifetime in C . 9 2.1.1 Global Variables . 11 2.1.2 Automatic Variables . 12 2.1.3 Register variables . 13 2.1.4 Static Variables . 13 2.1.5 Volatile Variables . 16 2.2 Summary Table . 17 2.3 Terms and Definitions . 17 ii Contents 3 Compiling & Linking: From Code to Executable 19 3.1 The Stages of Compilation . 19 3.1.1 The Preprocessor . 20 3.1.2 The Compiler . 21 3.1.3 The Linker . 22 3.2 Executable File Formats . -
C# Programming in Depth Lecture 4: Garbage Collection & Exception
Chair of Software Engineering C# Programming in Depth Prof. Dr. Bertrand Meyer March 2007 – May 2007 Lecture 4: Garbage Collection & Exception Handling Lisa (Ling) Liu Overview Scope and lifetime Garbage collection mechanism Exception handling C# programming lecture 4: Garbage Collection & Exception Handling 2 Scope and lifetime Scope of a variable is portion of program text within which it is declared ¾ Need not be contiguous ¾ In C#, is static: independent of data Lifetime or extent of storage is portion of program execution during which it exists ¾ Always contiguous ¾ Generally dynamic: dependent on data Class of lifetime ¾ Static: entire duration of program ¾ Local or automatic: duration of call or block execution (local variable) ¾ Dynamic: From time of allocation statement (new) to deallocation, if any. C# programming lecture 4: Garbage Collection & Exception Handling 3 Object lifetime in C# Memory allocation for an object should be made using the “new” keyword Objects are allocated onto the managed heap, where they are automatically deallocated by the runtime at “some time in the future” Garbage collection is automated in C# Rule: Allocate an object onto the managed heap using the new keyword and forget about it C# programming lecture 4: Garbage Collection & Exception Handling 4 Object creation When a call to new is made, it creates a CIL “newobj” instruction to the code module public static int Main (string[] args) { Car c = new Car(“Viper”, 200, 100); } IL_000c: newobj instance void CilNew.Car::.ctor (string, int32, -
Foreign Library Interface by Daniel Adler Dia Applications That Can Run on a Multitude of Plat- Forms
30 CONTRIBUTED RESEARCH ARTICLES Foreign Library Interface by Daniel Adler dia applications that can run on a multitude of plat- forms. Abstract We present an improved Foreign Function Interface (FFI) for R to call arbitary na- tive functions without the need for C wrapper Foreign function interfaces code. Further we discuss a dynamic linkage framework for binding standard C libraries to FFIs provide the backbone of a language to inter- R across platforms using a universal type infor- face with foreign code. Depending on the design of mation format. The package rdyncall comprises this service, it can largely unburden developers from the framework and an initial repository of cross- writing additional wrapper code. In this section, we platform bindings for standard libraries such as compare the built-in R FFI with that provided by (legacy and modern) OpenGL, the family of SDL rdyncall. We use a simple example that sketches the libraries and Expat. The package enables system- different work flow paths for making an R binding to level programming using the R language; sam- a function from a foreign C library. ple applications are given in the article. We out- line the underlying automation tool-chain that extracts cross-platform bindings from C headers, FFI of base R making the repository extendable and open for Suppose that we wish to invoke the C function sqrt library developers. of the Standard C Math library. The function is de- clared as follows in C: Introduction double sqrt(double x); We present an improved Foreign Function Interface The .C function from the base R FFI offers a call (FFI) for R that significantly reduces the amount of gate to C code with very strict conversion rules, and C wrapper code needed to interface with C. -
Debugging Mixedenvironment Programs with Blink
SOFTWARE – PRACTICE AND EXPERIENCE Softw. Pract. Exper. (2014) Published online in Wiley Online Library (wileyonlinelibrary.com). DOI: 10.1002/spe.2276 Debugging mixed-environment programs with Blink Byeongcheol Lee1,*,†, Martin Hirzel2, Robert Grimm3 and Kathryn S. McKinley4 1Gwangju Institute of Science and Technology, Gwangju, Korea 2IBM, Thomas J. Watson Research Center, Yorktown Heights, NY, USA 3New York University, New York, NY, USA 4Microsoft Research, Redmond, WA, USA SUMMARY Programmers build large-scale systems with multiple languages to leverage legacy code and languages best suited to their problems. For instance, the same program may use Java for ease of programming and C to interface with the operating system. These programs pose significant debugging challenges, because programmers need to understand and control code across languages, which often execute in different envi- ronments. Unfortunately, traditional multilingual debuggers require a single execution environment. This paper presents a novel composition approach to building portable mixed-environment debuggers, in which an intermediate agent interposes on language transitions, controlling and reusing single-environment debug- gers. We implement debugger composition in Blink, a debugger for Java, C, and the Jeannie programming language. We show that Blink is (i) simple: it requires modest amounts of new code; (ii) portable: it supports multiple Java virtual machines, C compilers, operating systems, and component debuggers; and (iii) pow- erful: composition eases debugging, while supporting new mixed-language expression evaluation and Java native interface bug diagnostics. To demonstrate the generality of interposition, we build prototypes and demonstrate debugger language transitions with C for five of six other languages (Caml, Common Lisp, C#, Perl 5, Python, and Ruby) without modifications to their debuggers. -
Analyzing a Decade of Linux System Calls
Noname manuscript No. (will be inserted by the editor) Analyzing a Decade of Linux System Calls Mojtaba Bagherzadeh Nafiseh Kahani · · Cor-Paul Bezemer Ahmed E. Hassan · · Juergen Dingel James R. Cordy · Received: date / Accepted: date Abstract Over the past 25 years, thousands of developers have contributed more than 18 million lines of code (LOC) to the Linux kernel. As the Linux kernel forms the central part of various operating systems that are used by mil- lions of users, the kernel must be continuously adapted to changing demands and expectations of these users. The Linux kernel provides its services to an application through system calls. The set of all system calls combined forms the essential Application Programming Interface (API) through which an application interacts with the kernel. In this paper, we conduct an empirical study of the 8,770 changes that were made to Linux system calls during the last decade (i.e., from April 2005 to December 2014) In particular, we study the size of the changes, and we manually identify the type of changes and bug fixes that were made. Our analysis provides an overview of the evolution of the Linux system calls over the last decade. We find that there was a considerable amount of technical debt in the kernel, that was addressed by adding a number of sibling calls (i.e., 26% of all system calls). In addition, we find that by far, the ptrace() and signal handling system calls are the most difficult to maintain and fix. Our study can be used by developers who want to improve the design and ensure the successful evolution of their own kernel APIs. -
Generating Object Lifetime Traces with Merlin
Generating Object Lifetime Traces with Merlin MATTHEW HERTZ University of Massachusetts, Amherst STEPHEN M BLACKBURN Australian National University J ELIOT B MOSS University of Massachusetts, Amherst KATHRYN S McKINLEY University of Texas at Austin and DARKO STEFANOVIC´ University of New Mexico ÈÖÓÖÑÑÖ× Ö ÛÖØÒ ÖÔÐÝ ÖÓÛÒ ÒÙÑ Ö Ó ÔÖÓÖÑ× Ò Ó Ø ÐÒÙ׸ × ÂÚ Ò ¸ ØØ ÖÕÙÖ Ö Ö Ò ×ÑÙÐØÓÒ ×Ô ÜÔÐÓÖØÓÒ ÙÔ Ý ÒÐÒ Ô Ö ÙÒÖרÒÒ× Ó Ó ÐØÑ ÚÓÖ Ò Ò ×Ò Ó ÒÛ Ö ÐÓÖØÑ׺ ÏÒ ÒÖØÒ Ô Ø ÖÙØ¹ÓÖ ÑØÓ Ó Ó ÐØÑ× ÖÕÙÖ× ÛÓÐ¹Ô Ö Ø ÚÖÝ Ô ÓØÒØÐ Ô ÓÒØ Ò Ø ÔÖÓÖѺ Ø× ÔÖÓ × ÔÖÓØÚÐÝ ÜÔ Ò×Ú¸ Ö× ÓØÒ ÒÙÐØ Ý ÓÒÐÝ Ô ÖÓ ¸ ºº¸ ÚÖÝ ¿¾Ã ÝØ× Ó ÐÐÓ Ù× Ö Û Ï ÜØÒ Ø ×ØØ Ó Ø ÖØ ÓÖ ×ÑÙÐØÒ Ö ÐÓÖØÑ× Ò ØÛÓÛÝ׺ Öר¸ ÚÐÓÔ ÑØÓ ÓÐÓÝ ÓÖ ×ÑÙÐØÓÒ ×ØÙ× Ó ÝÒ Ö Ò ÔÖ×ÒØ Ö×ÙÐØ× ×ÓÛÒ Ø Ó ÖÒÙÐÖØÝ ÓÒ Ø× ×ÑÙÐØÓÒ׺ Ï ×ÓÛ ØØ ÖÒÙÐÖØÝ ÓØÒ ×ØÓÖØ× ×ÑÙÐØ Ö Ö×ÙÐØ× ÛØ Ô Û ÓÖ Ó ÔÖ×ÒØ Ò Ñ×ÙÖ Ø Ô Ó ÒÛ ÐÓÖØÑ ÅÖÐÒ ÐØÑ׺ ÅÖÐÒ ØÑרÑÔ× Ó Ò ÐØÖ Ù×× Ø ØÑרÑÔ× Ó Ó ØÓ ÛÒ ØÝ º Ì ÅÖÐÒ ÐÓÖØÑ × ÓÒ Ö Ô ÖÓÖÑ Ý Ø × ÖÑÒØÐ Ö×ÙÐØ× ×ÓÛ ØØ ÅÖÐÒ ÒÖØ ÓÚÖ ØÛÓ ÓÖÖ× Ó ÑÒØÙ ×Ý×ØÑº ÜÔ ×ØÖ ØÒ Ø ÑØÓ ØÖ ÚÖÝ Ó ÐÐÓ Ï Ð×Ó Ù× ÅÖÐÒ ØÓ ÔÖÓ Ú×ÙÐÞØÓÒ× Ó Ô ÚÓÖ ØØ ÜÔ Ó× ÒÛ Ó ÐØÑ ÚÓÖ׺ Categories and Subject Descriptors: D.3.4 [Programming Languages]: Processors—memory management (gar- bage collection) ÒÖÐ ÌÖÑ× ÐÓÖØÑ׸ ÄÒÙ׸ È ØÓÒÐ ÃÝ ÏÓÖ× Ò ÈÖ×× Ö ×Ò¸ Ó ÐØÑ ÒÐÝ×׸ ÒÖØÓÒ This work is supported by NSF grants CCR-0219587, ITR CCR-0085792, EIA-0218262, EIA-9726401, EIA- 030609, EIA-0238027, EIA-0324845, DARPA F33615-03-C-4106, Hewlett-Packard gift 88425.1, Microsoft Re- search, and IBM. -
Modern C++ Object-Oriented Programming
CPP Modern C++ Object-Oriented Programming ''Combine old and newer features to get the best out of the language'' Margit ANTAL 2020 C++ - Object-Oriented Programming Course content − Introduction to C++ − Object-oriented programming − Generic programming and the STL − Object-oriented design C++ - Object-Oriented Programming References − Bjarne Stroustrup, Herb Sutter, C++ Core Guidelines, 2017. rd − M. Gregoire, Professional C++, 3 edition, John Wiley & Sons, 2014. th − S. Lippman, J. Lajoie, B. E. Moo, C++ Primer, 5 edition, Addison Wesley, , 2013. th − S. Prata, C++ Primer Plus, 6 edition, Addison Wesley, 2012. − N. Josuttis, The C++ standard library. a tutorial and reference. Pearson Education. 2012. − A. Williams, C++ Concurrency in Action:Practical Multithreading. Greenwich, CT: Manning. 2012. Module 1 Introduction to C++ Introduction to C++ Content − History and evolution − Overview of the key features ● New built-in types ● Scope and namespaces ● Enumerations ● Dynamic memory: new and delete ● Smart pointers: unique_ptr, shared_ptr, weak_ptr ● Error handling with exceptions ● References ● The const modifier Introduction to C++ History and evolution − Creator: Bjarne Stroustrup 1983 − Standards: ● The first C++ standard − 1998 (C++98, major) − 2003 (C++03, minor) ● The second C++ standard − 2011 (C++11, major) – significant improvements in language and library − 2014 (C++14, minor) − 2017 (C++17, major) Introduction to C+ History and evolution − source: https://isocpp.org/std/status Introduction to C+ History and evolution − source: -
Name, Scope and Binding (2) in Text: Chapter 5
Name, Scope and Binding (2) In Text: Chapter 5 N. Meng, F. Poursardar Variable • A program variable is an abstraction of a memory cell or a collection of cells • It has several attributes – Name: A mnemonic character string – Address – Type 2 Variable Attributes (continued) • Storage Bindings – Allocation o Getting a memory cell from a pool of available memory to bind to a variable – Deallocation o Putting a memory cell that has been unbound from a variable back into the pool • Lifetime – The lifetime of a variable is the time during which it is bound to a particular memory cell 3 Object Lifetime and Storage Management • Key events: creation of objects, creation of bindings, references to variables (which use bindings), (temporary) deactivation of bindings, reactivation of bindings, destruction of bindings, and destruction of objects. • Binding lifetime: the period of time from creation to destruction of a name-to-object binding. • Object lifetime: the time between the creation and destruction of an objects is the object’s lifetime: – If object outlives binding it's garbage. – If binding outlives object it's a dangling reference. • Scope: the textual region of the program in which the binding is active; we sometimes use the word scope as a noun all by itself, without an indirect object. Lifetime • If an object’s memory binding outlives its access binding, we get garbage • If an object’s access binding outlives its memory binding, we get a dangling reference • Variable lifetime begins at allocation, and ends at deallocation either by the program or garbage collector 5 Categories of Variables by Lifetimes • Static • Stack-dynamic • Explicit heap-dynamic • Implicit heap-dynamic Storage Allocation Mechanisms • Static: objects are given an absolute address that is retained throughout the program’s execution.