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Hash Array Mapped Trie
A hash array mapped trie (HAMT, ) is an implementation of an associative array that combines the characteristics of a hash table and an array mapped trie. It is a refined version of the more general notion of a hash tree. Operation A HAMT is an array mapped trie where the keys are first hashed to ensure an even distribution of keys and a constant key length. In a typical implementation of HAMT's array mapped trie, each node contains a table with some fixed number N of slots with each slot containing either a nil pointer or a pointer to another node. N is commonly 32. As allocating space for N pointers for each node would be expensive, each node instead contains a bitmap which is N bits long where each bit indicates the presence of a non-nil pointer. This is followed by an array of pointers equal in length to the number of ones in the bitmap (its Hamming weight). Advantages of HAMTs The hash array mapped trie achieves almost hash table-like speed while using memory much mor ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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Associative Array
In computer science, an associative array, key-value store, map, symbol table, or dictionary is an abstract data type that stores a collection of (key, value) pairs, such that each possible key appears at most once in the collection. In mathematical terms, an associative array is a function with ''finite'' domain. It supports 'lookup', 'remove', and 'insert' operations. The dictionary problem is the classic problem of designing efficient data structures that implement associative arrays. The two major solutions to the dictionary problem are hash tables and search trees..Dietzfelbinger, M., Karlin, A., Mehlhorn, K., Meyer auf der Heide, F., Rohnert, H., and Tarjan, R. E. 1994"Dynamic Perfect Hashing: Upper and Lower Bounds". SIAM J. Comput. 23, 4 (Aug. 1994), 738-761. http://portal.acm.org/citation.cfm?id=182370 It is sometimes also possible to solve the problem using directly addressed arrays, binary search trees, or other more specialized structures. Many programmin ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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JavaScript
JavaScript (), often abbreviated as JS, is a programming language and core technology of the World Wide Web, alongside HTML and CSS. Ninety-nine percent of websites use JavaScript on the client side for webpage behavior. Web browsers have a dedicated JavaScript engine that executes the client code. These engines are also utilized in some servers and a variety of apps. The most popular runtime system for non-browser usage is Node.js. JavaScript is a high-level, often just-in-time–compiled language that conforms to the ECMAScript standard. It has dynamic typing, prototype-based object-orientation, and first-class functions. It is multi-paradigm, supporting event-driven, functional, and imperative programming styles. It has application programming interfaces (APIs) for working with text, dates, regular expressions, standard data structures, and the Document Object Model (DOM). The ECMAScript standard does not include any input/output (I/O), such as netwo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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Radix Tree
In computer science, a radix tree (also radix trie or compact prefix tree or compressed trie) is a data structure that represents a space-optimized trie (prefix tree) in which each node that is the only child is merged with its parent. The result is that the number of children of every internal node is at most the radix of the radix tree, where = 2 for some integer ≥ 1. Unlike regular trees, edges can be labeled with sequences of elements as well as single elements. This makes radix trees much more efficient for small sets (especially if the strings are long) and for sets of strings that share long prefixes. Unlike regular trees (where whole keys are compared ''en masse'' from their beginning up to the point of inequality), the key at each node is compared chunk-of-bits by chunk-of-bits, where the quantity of bits in that chunk at that node is the radix of the radix trie. When is 2, the radix trie is binary (i.e., compare that node's 1-bit portion of the key), which mini ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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Judy Array
In computer science, a Judy array is an early-2000s Hewlett-Packard hand-optimized implementation of a 256-ary radix tree that uses many situational node types to reduce latency from CPU cache-line fills.Alan Silverstein,Judy IV Shop Manual, 2002 As a compressed radix tree, a Judy array can store potentially sparse integer- or string-indexed data with comparatively low memory usage and low read latency, without relying on hashing or tree balancing, and without sacrificing in-order traversal. Per-operation latency scales as O(\log n)—as expected of a tree—and the leading constant factor is small enough that Judy arrays are suitable even to the peta-element range. When applicable, they can be faster than implementations of AVL trees, B-trees, hash tables, or skip lists from the same time period. History The Judy array was invented by Douglas Baskins over the years leading up to 2002 and named after his sister. Node types Broadly, tree nodes in Judy arrays fall into one of three ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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Lock Free
In computer science, an algorithm is called non-blocking if failure or suspension of any thread cannot cause failure or suspension of another thread; for some operations, these algorithms provide a useful alternative to traditional blocking implementations. A non-blocking algorithm is lock-free if there is guaranteed system-wide progress, and wait-free if there is also guaranteed per-thread progress. "Non-blocking" was used as a synonym for "lock-free" in the literature until the introduction of obstruction-freedom in 2003. The word "non-blocking" was traditionally used to describe telecommunications networks that could route a connection through a set of relays "without having to re-arrange existing calls" (see Clos network). Also, if the telephone exchange "is not defective, it can always make the connection" (see nonblocking minimal spanning switch). Motivation The traditional approach to multi-threaded programming is to use locks to synchronize access to shared res ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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Linearizability
In concurrent programming, an operation (or set of operations) is linearizable if it consists of an ordered list of invocation and response events, that may be extended by adding response events such that: # The extended list can be re-expressed as a sequential history (is serializable). # That sequential history is a subset of the original unextended list. Informally, this means that the unmodified list of events is linearizable if and only if its invocations were serializable, but some of the responses of the serial schedule have yet to return. In a concurrent system, processes can access a shared object at the same time. Because multiple processes are accessing a single object, a situation may arise in which while one process is accessing the object, another process changes its contents. Making a system linearizable is one solution to this problem. In a linearizable system, although operations overlap on a shared object, each operation appears to take place instantaneousl ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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Atomicity (programming)
Atomicity may refer to: Chemistry * Atomicity (chemistry), the total number of atoms present in 1 molecule of a substance * Valence (chemistry) In chemistry, the valence (US spelling) or valency (British spelling) of an atom is a measure of its combining capacity with other atoms when it forms chemical compounds or molecules. Valence is generally understood to be the number of chemica ..., sometimes referred to as atomicity Computing * Atomicity (database systems), a property of database transactions which are guaranteed to either completely occur, or have no effects * Atomicity (programming), an operation appears to occur at a single instant between its invocation and its response * Atomicity, a property of an S-expression, in a symbolic language like Lisp Mathematics * Atomicity, an element of orthogonality in a component-based system * Atomicity, in order theory; see Atom (order theory) See also * Atom (other) {{Disambiguation ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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Ctrie
A concurrent hash-trie or Ctrie is a concurrent thread-safe lock-free implementation of a hash array mapped trie. It is used to implement the concurrent map abstraction. It has particularly scalable concurrent insert and remove operations and is memory-efficient. It is the first known concurrent data-structure that supports O(1), atomic, lock-free snapshots. Operation The Ctrie data structure is a non-blocking concurrent hash array mapped trie based on single-word compare-and-swap instructions in a shared-memory system. It supports concurrent lookup, insert and remove operations. Just like the hash array mapped trie, it uses the entire 32-bit space for hash values thus having low risk of hashcode collisions. Each node may have up to 32 sub-nodes, but to conserve memory, the list of sub-nodes is represented by a 32-bit bitmap where each bit indicates the presence of a branch, followed by a non-sparse array (of pointers to sub-nodes) whose length equals the Hamming weight of the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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Erlang (programming Language)
Erlang ( ) is a general-purpose, concurrent, functional high-level programming language, and a garbage-collected runtime system. The term Erlang is used interchangeably with Erlang/OTP, or Open Telecom Platform (OTP), which consists of the Erlang runtime system, several ready-to-use components (OTP) mainly written in Erlang, and a set of design principles for Erlang programs. The Erlang runtime system is designed for systems with these traits: * Distributed * Fault-tolerant * Soft real-time * Highly available, non-stop applications * Hot swapping, where code can be changed without stopping a system. The Erlang programming language has immutable data, pattern matching, and functional programming. The sequential subset of the Erlang language supports eager evaluation, single assignment, and dynamic typing. A normal Erlang application is built out of hundreds of small Erlang processes. It was originally proprietary software within Ericsson, developed by Joe Armstrong ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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Ruby (programming Language)
Ruby is a general-purpose programming language. It was designed with an emphasis on programming productivity and simplicity. In Ruby, everything is an object (computer science), object, including primitive data types. It was developed in the mid-1990s by Yukihiro Matsumoto, Yukihiro "Matz" Matsumoto in Japan. Ruby is interpreted language, interpreted, high-level programming language, high-level, and Dynamic typing, dynamically typed; its interpreter uses garbage collection (computer science), garbage collection and just-in-time compilation. It supports multiple programming paradigms, including procedural programming, procedural, object-oriented programming, object-oriented, and functional programming. According to the creator, Ruby was influenced by Perl, Smalltalk, Eiffel (programming language), Eiffel, Ada (programming language), Ada, BASIC, and Lisp (programming language), Lisp. History Early concept According to Matsumoto, Ruby was conceived in 1993. In a 1999 post to t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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GitHub
GitHub () is a Proprietary software, proprietary developer platform that allows developers to create, store, manage, and share their code. It uses Git to provide distributed version control and GitHub itself provides access control, bug tracking system, bug tracking, software feature requests, task management, continuous integration, and wikis for every project. Headquartered in California, GitHub, Inc. has been a subsidiary of Microsoft since 2018. It is commonly used to host open source software development projects. GitHub reported having over 100 million developers and more than 420 million Repository (version control), repositories, including at least 28 million public repositories. It is the world's largest source code host Over five billion developer contributions were made to more than 500 million open source projects in 2024. About Founding The development of the GitHub platform began on October 19, 2005. The site was launched in April 2008 by Tom ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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Rubinius
Rubinius is an alternative Ruby implementation created by Evan Phoenix. Based loosely on the Smalltalk-80 ''Blue Book'' design, Rubinius seeks to "provide a rich, high-performance environment for running Ruby code." Goals Rubinius follows in the Lisp and Smalltalk traditions, by natively implementing as much of Ruby as possible in Ruby code. It also has a goal of being thread-safe in order to be able to embed more than one interpreter in a single application. Sponsorship From 2007 to 2013, Engine Yard funded one full-time engineer to work exclusively on Rubinius. Evan Phoenix now works at HashiCorp. PowerPC64 support Since version 2.4.0, support on PowerPC64 is enabled. See also * Jikes RVM * JRuby * MacRuby *MagLev * Parrot virtual machine * PyPy * Squawk * Squeak Squeak is an object-oriented, class-based, and reflective programming language. It was derived from Smalltalk-80 by a group that included some of Smalltalk-80's original developers, initially a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |