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LuaJIT
LuaJIT is a tracing just-in-time compiler and interpreter for the Lua programming language. History The LuaJIT project was started in 2005 by developer Mike Pall, released under the MIT open source license. The second major release of the compiler, 2.0.0, featured major performance increases. LuaJIT uses rolling releases. Mike Pall, the creator and maintainer recommends using the tip of the v2.1 branch, and does not believe in releases. Mike Pall resigned in 2015 making only occasional patching to the future 2.1 version since then. Notable users * CERN, for their Methodical Accelerator Design 'next-generation' software for describing and simulating particle accelerators * OpenResty, a fork of nginx with Lua scripting * Neovim, a text editor based on vim that allows the use of Lua for plugins and configuration * Kong, a web API gateway * Cloudflare, who use LuaJIT in their web application firewall service Performance LuaJIT is often the fastest Lua runtime. LuaJIT h ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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Lua (programming Language)
Lua is a lightweight, high-level, multi-paradigm programming language designed mainly for embedded use in applications. Lua is cross-platform software, since the interpreter of compiled bytecode is written in ANSI C, and Lua has a relatively simple C application programming interface ( API) to embed it into applications. Lua originated in 1993 as a language for extending software applications to meet the increasing demand for customization at the time. It provided the basic facilities of most procedural programming languages, but more complicated or domain-specific features were not included; rather, it included mechanisms for extending the language, allowing programmers to implement such features. As Lua was intended to be a general embeddable extension language, the designers of Lua focused on improving its speed, portability, extensibility and ease-of-use in development. History Lua was created in 1993 by Roberto Ierusalimschy, Luiz Henrique de Figueiredo and Wa ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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OpenResty
OpenResty is an nginx distribution which includes the LuaJIT interpreter for Lua scripts. The software was created by Yichun Zhang. It was originally sponsored by Taobao before 2011 and was mainly supported by Cloudflare from 2012 to 2016. Since 2017, it has been mainly supported by OpenResty Software Foundation and OpenResty Inc. OpenResty is designed to build scalable web applications, web services, and dynamic web gateways. The OpenResty architecture is based on several nginx modules which have been extended in order to expand nginx into a web app server to handle large number of requests. OpenResty aims to run Lua server-side applications completely in the Nginx server, leveraging its event model to do non-blocking I/O not only for client connections, but also with remote resources, such as databases. History In October 2007, OpenResty began at Yahoo! China as an Open API web service framework written mostly in Perl. Its README at CPAN describes it as "A REST wrapper fo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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Tracing Just-in-time Compilation
Tracing just-in-time compilation is a technique used by virtual machines to Optimization (computer science), optimize the execution of a program at Run time (program lifecycle phase), runtime. This is done by recording a linear sequence of frequently executed operations, compiler, compiling them to Native code, native machine code and executing them. This is opposed to traditional Just-in-time compilation, just-in-time (JIT) compilers that work on a per-method basis. Overview Just-in-time compilation is a technique to increase execution speed of programs by compiling parts of a program to machine code at runtime. One way to categorize different JIT compilers is by their compilation scope. Whereas method-based JIT compilers translate one method at a time to machine code, tracing JITs use frequently executed loops as their unit of compilation. Tracing JITs are based on the assumptions that programs spend most of their time in some Loop (computing)#Loops, loops of the program ("hot l ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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Static Single-assignment Form
In compiler design, static single assignment form (often abbreviated as SSA form or simply SSA) is a type of intermediate representation (IR) where each variable is assigned exactly once. SSA is used in most high-quality optimizing compilers for imperative languages, including LLVM, the GNU Compiler Collection, and many commercial compilers. There are efficient algorithms for converting programs into SSA form. To convert to SSA, existing variables in the original IR are split into versions, new variables typically indicated by the original name with a subscript, so that every definition gets its own version. Additional statements that assign to new versions of variables may also need to be introduced at the join point of two control flow paths. Converting from SSA form to machine code is also efficient. SSA makes numerous analyses needed for optimizations easier to perform, such as determining use-define chains, because when looking at a use of a variable there is only one place ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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Tracing Just-in-time Compiler
Tracing just-in-time compilation is a technique used by virtual machines to optimize the execution of a program at runtime. This is done by recording a linear sequence of frequently executed operations, compiling them to native machine code and executing them. This is opposed to traditional just-in-time (JIT) compilers that work on a per-method basis. Overview Just-in-time compilation is a technique to increase execution speed of programs by compiling parts of a program to machine code at runtime. One way to categorize different JIT compilers is by their compilation scope. Whereas method-based JIT compilers translate one method at a time to machine code, tracing JITs use frequently executed loops as their unit of compilation. Tracing JITs are based on the assumptions that programs spend most of their time in some loops of the program ("hot loops") and subsequent loop iterations often take similar paths. Virtual machines that have a tracing JIT are often mixed-mode execution en ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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Foreign Function Interface
A foreign function interface (FFI) is a mechanism by which a program written in one programming language can call routines or make use of services written or compiled in another one. An FFI is often used in contexts where calls are made into a binary dynamic-link library. Naming The term comes from the specification for Common Lisp, which explicitly refers to the programming language feature enabling for inter-language calls as such; the term is also often used officially by the interpreter and compiler documentation for Haskell, Rust, PHP, Python, and LuaJIT ( Lua). Other languages use other terminology: Ada has ''language bindings'', while Java has '' Java Native Interface'' (JNI) or '' Java Native Access'' (JNA). Foreign function interface has become generic terminology for mechanisms which provide such services. Operation The primary function of a foreign function interface is to mate the semantics and calling conventions of one programming language (the ''host'' lan ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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Operator (computer Programming)
In computer programming, an operator is a programming language construct that provides functionality that may not be possible to define as a user-defined function (i.e. sizeof in C) or has syntax different than a function (i.e. infix addition as in a+b). Like other programming language concepts, ''operator'' has a generally accepted, although debatable meaning among practitioners while at the same time each language gives it specific meaning in that context, and therefore the meaning varies by language. Some operators are represented with symbols characters typically not allowed for a function identifier to allow for presentation that is more familiar looking than typical function syntax. For example, a function that tests for greater-than could be named gt, but many languages provide an infix symbolic operator so that code looks more familiar. For example, this: if gt(x, y) then return Can be: if x > y then return Some languages allow a language-defined operator t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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Branch Table
A branch, also called a ramus in botany, is a Plant stem, stem that grows off from another stem, or when structures like veins in leaves are divided into smaller veins. History and etymology In Old English, there are numerous words for branch, including , , , and . There are also numerous descriptive words, such as (that is, something that has bled, or 'bloomed', out), (literally 'little bough'), (literally 'on growth'), and (literally 'offspringing'). Numerous other words for twigs and boughs abound, including , which still survives as the ''-toe'' in ''mistletoe''. Latin words for branch are or . The latter term is an affix found in other modern words such as ''cladodont'' (prehistoric sharks with branched teeth), ''cladode'' (flattened leaf-like branches), or ''cladogram'' (a branched diagram showing relations among organisms). Woody branches Large branches are known as boughs and small branches are known as twigs. The term ''twig'' usually refers to a wikt:terminu ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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Inline Expansion
In computing, inline expansion, or inlining, is a manual or compiler optimization that replaces a function call site with the body of the called function. Inline expansion is similar to macro expansion, but occurs during compiling, without changing the source code (the text), while macro expansion occurs before compiling, and results in different text that is then processed by the compiler. Inlining is an important optimization, but has complex effects on performance. As a rule of thumb, some inlining will improve speed at very minor cost of space, but excess inlining will hurt speed, due to inlined code consuming too much of the instruction cache, and also cost significant space. A survey of the modest academic literature on inlining from the 1980s and 1990s is given in Peyton Jones & Marlow 1999. Overview Inline expansion is similar to macro expansion as the compiler places a new copy of the function in each place it is called. Inlined functions run a little faster than the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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Intermediate Representation
An intermediate representation (IR) is the data structure or code used internally by a compiler or virtual machine to represent source code. An IR is designed to be conducive to further processing, such as optimization and translation. A "good" IR must be ''accurate'' – capable of representing the source code without loss of information – and ''independent'' of any particular source or target language. An IR may take one of several forms: an in-memory data structure, or a special tuple- or stack-based code readable by the program. In the latter case it is also called an ''intermediate language''. A canonical example is found in most modern compilers. For example, the CPython interpreter transforms the linear human-readable text representing a program into an intermediate graph structure that allows flow analysis and re-arrangement before execution. Use of an intermediate representation such as this allows compiler systems like the GNU Compiler Collection and LLVM to be u ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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Hot Path
A hot spot in computer science is most usually defined as a region of a computer program where a high proportion of executed instructions occur or where most time is spent during the program's execution (not necessarily the same thing since some instructions are faster than others). If a program is interrupted randomly, the program counter (the pointer to the next instruction to be executed) is frequently found to contain the address of an instruction within a certain range, possibly indicating code that is in need of optimization or even indicating the existence of a 'tight' CPU loop. This simple technique can detect highly used instructions, although more-sophisticated methods, such as instruction set simulators or performance analyzers, achieve this more accurately and consistently. History of hot spot detection The computer scientist Donald Knuth described his first encounter with what he refers to as a ''jump trace'' in an interview for ''Dr. Dobb's Journal'' in 1996, sayi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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Web Application Firewall
A web application firewall (WAF) is a specific form of application firewall that filters, monitors, and blocks HTTP traffic to and from a web service. By inspecting HTTP traffic, it can prevent attacks exploiting a web application's known vulnerabilities, such as SQL injection, cross-site scripting (XSS), file inclusion, and improper system configuration. Most of the major financial institutions utilize WAFs to help in the mitigation of web application "zero-day" vulnerabilities, as well as hard-to-patch bugs or weaknesses through custom attack signature strings. History Dedicated web application firewalls entered the market in the late 1990s during a time when web server attacks were becoming more prevalent. Early WAF products, from Kavado and Gilian technologies, were available, trying to solve the increasing amount of attacks on web applications in the late 1990s. In 2002, the open-source project ModSecurity was formed in order to make WAF technology more accessible ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |