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Atomic Commit
In the field of computer science, an atomic commit is an operation that applies a set of distinct changes as a single operation. If the changes are applied, then the atomic commit is said to have succeeded. If there is a failure before the atomic commit can be completed, then all of the changes completed in the atomic commit are reversed. This ensures that the system is always left in a consistent state. The other key property of isolation comes from their nature as atomic operations. Isolation ensures that only one atomic commit is processed at a time. The most common uses of atomic commits are in database systems and version control systems. The problem with atomic commits is that they require coordination between multiple systems. As computer networks are unreliable services, this means no algorithm can coordinate with all systems as proven in the Two Generals Problem. As databases become more and more distributed, this coordination will increase the difficulty of making trul ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Computer Science
Computer science is the study of computation, automation, and information. Computer science spans theoretical disciplines (such as algorithms, theory of computation, information theory, and automation) to Applied science, practical disciplines (including the design and implementation of Computer architecture, hardware and Computer programming, software). Computer science is generally considered an area of research, academic research and distinct from computer programming. Algorithms and data structures are central to computer science. The theory of computation concerns abstract models of computation and general classes of computational problem, problems that can be solved using them. The fields of cryptography and computer security involve studying the means for secure communication and for preventing Vulnerability (computing), security vulnerabilities. Computer graphics (computer science), Computer graphics and computational geometry address the generation of images. Progr ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Concurrent Versions System
Concurrent Versions System (CVS, also known as the Concurrent Versioning System) is a revision control system originally developed by Dick Grune in July 1986. CVS operates as a front end to RCS, an earlier system which operates on single files. It expands upon RCS by adding support for repository-level change tracking, and a client-server model. Released under the terms of the GNU General Public License, CVS is free software. Design CVS operates as a front end to Revision Control System (RCS), an older version control system that manages individual files but not whole projects. It expands upon RCS by adding support for repository-level change tracking, and a client-server model. Files are tracked using the same history format as in RCS, with a hidden directory containing a corresponding history file for each file in the repository. CVS uses delta compression for efficient storage of different versions of the same file. This works well with large text files with few cha ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Transaction Processing
Transaction processing is information processing in computer science that is divided into individual, indivisible operations called ''transactions''. Each transaction must succeed or fail as a complete unit; it can never be only partially complete. For example, when you purchase a book from an online bookstore, you exchange money (in the form of credit) for a book. If your credit is good, a series of related operations ensures that you get the book and the bookstore gets your money. However, if a single operation in the series fails during the exchange, the entire exchange fails. You do not get the book and the bookstore does not get your money. The technology responsible for making the exchange balanced and predictable is called transaction processing. Transactions ensure that data-oriented resources are not permanently updated unless all operations within the transactional unit complete successfully. By combining a set of related operations into a unit that either completely s ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Atomic Operation
In concurrent programming, an operation (or set of operations) is linearizable if it consists of an ordered list of invocation and response events (event), 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, there may arise a situation 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 i ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Three-phase Commit Protocol
In computer networking and databases, the three-phase commit protocol (3PC) is a distributed algorithm which lets all nodes in a distributed system agree to commit a transaction. It is a more failure-resilient refinement of the two-phase commit protocol (2PC). Motivation A two-phase commit protocol cannot dependably recover from a failure of both the coordinator and a cohort member during the Commit phase. If only the coordinator had failed, and no cohort members had received a commit message, it could safely be inferred that no commit had happened. If, however, both the coordinator and a cohort member failed, it is possible that the failed cohort member was the first to be notified, and had actually done the commit. Even if a new coordinator is selected, it cannot confidently proceed with the operation until it has received an agreement from all cohort members, and hence must block until all cohort members respond. The three-phase commit protocol eliminates this problem by in ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Two-phase Commit Protocol
In transaction processing, databases, and computer networking, the two-phase commit protocol (2PC) is a type of atomic commitment protocol (ACP). It is a distributed algorithm that coordinates all the processes that participate in a distributed atomic transaction on whether to commit or abort (roll back) the transaction. This protocol (a specialised type of consensus protocol) achieves its goal even in many cases of temporary system failure (involving either process, network node, communication, etc. failures), and is thus widely used. Philip A. Bernstein, Vassos Hadzilacos, Nathan Goodman (1987) ''Concurrency Control and Recovery in Database Systems'' Chapter 7, Addison Wesley Publishing Company, Gerhard Weikum, Gottfried Vossen (2001) ''Transactional Information Systems'' Chapter 19, Elsevier, Philip A. Bernstein, Eric Newcomer (2009)''Principles of Transaction Processing'', 2nd Edition, Chapter 8, Morgan Kaufmann (Elsevier), However, it is not resilient to all possible fail ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Reversion (software Development)
In software development (and, by extension, in content-editing environments, especially wikis, that make use of the software development process of revision control), reversion or reverting is the abandonment of one or more recent changes in favor of a return to a previous version of the material at hand (typically software source code in the context of application development; HTML, CSS or script code in the context of web development; or content and formatting thereof in the context of wikis). A revert may be done for a wide variety of reasons, including: fixing errors introduced by previous edits; restoring the material to a state that was not contentious until new disputes can be resolved; undoing scope creep Scope creep (also called requirement creep, or kitchen sink syndrome) in project management refers to changes, continuous or uncontrolled growth in a project’s scope, at any point after the project begins. This can occur when the scope of a p ...; regression te ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Monorepo
In version-control systems, a monorepo ("mono" meaning 'single' and "repo" being short for ' repository') is a software-development strategy in which the code for a number of projects is stored in the same repository. This practice dates back to at least the early 2000s, when it was commonly called a shared codebase. Google, Meta, Microsoft, Uber, Airbnb, and Twitter all employ very large monorepos with varying strategies to scale build systems and version control software with a large volume of code and daily changes. A related concept is the monolithic application, but whereas a monolith combines its sub-projects into one large project, a monorepo may contain multiple independent projects. Advantages There are a number of potential advantages to a monorepo over individual repositories: ; Ease of code reuse : Similar functionality or communication protocols can be abstracted into shared libraries and directly included by projects, without the need of a dependency package ma ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Changeset
In version control software, a changeset (also known as commit and revision) is a set of alterations packaged together, along with meta-information about the alterations. A changeset describes the exact differences between two successive versions in the version control system's repository of changes. Changesets are typically treated as an atomic unit, an indivisible set, by version control systems. This is one synchronization model. Terminology In the Git version control system a changeset is called a commit, not to be confused with the commit operation that is used to commit a changeset (or in Git's case technically a snapshot) to a repository. Other version control systems also use other names to refer to changesets, for example Darcs calls them "patches", while Pijul refers to them as "changes". Metadata Version control systems attach metadata to changesets. Typical metadata includes a description provided by the programmer (a "commit message" in Git lingo), the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Edit Conflict
An edit conflict is a computer problem that may occur when multiple editors edit the same file and cannot merge without losing part of their edits. Description The conflict occurs when an editor gets a copy of a shared document file, changes the copy, and attempts to save the changes to the original file, which has been altered by another editor after the copy was obtained. Resolution The simplest way to resolve an edit conflict is to ignore intervening edits and overwrite the current file. This may lead to a substantial loss of information, and alternative methods are often employed to resolve or prevent conflicts. * Manual resolution, where the editor determines which version to retain and may manually incorporate edits into the current version of the file. * Store backups or file comparisons of each edit, so there are the previous versions of the file can still be accessed once the original is overwritten. * File locking, which limits the file to one editor at a time to ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
IBM Rational ClearCase
Rational ClearCase is a family of computer software tools that supports software configuration management (SCM) of source code and other software development assets. It also supports design-data management of electronic design artifacts, thus enabling hardware and software co-development. ClearCase includes revision control and forms the basis for configuration management at large and medium-sized businesses, accommodating projects with hundreds or thousands of developers. It is developed by IBM. ClearCase supports two configuration management models: UCM (Unified Change Management) and base ClearCase. UCM provides an out-of-the-box model while base ClearCase provides a basic infrastructure (UCM is built on base ClearCase). Both can be configured to support a wide variety of needs. ClearCase can accommodate large binary files, large numbers of files, and large repository sizes. It supports branching, labeling, and versioning of directories. It uses the MultiVersion File System (M ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Microsoft Visual SourceSafe
Microsoft Visual SourceSafe (VSS) is a discontinued source control program oriented towards small software development projects. Like most source control systems, SourceSafe creates a ''virtual library'' of computer files. While most commonly used for source code, SourceSafe can handle any type of file in its database, but older versions were shown to be unstable when used to store large amounts of non-textual data, such as images and compiled executables. History SourceSafe was originally created by a North Carolina company called One Tree Software. One Tree SourceSafe had gone through several releases in their 1.''x'' to 2.''x'' cycles, supporting DOS, OS/2 (with a Presentation Manager GUI), Windows, Windows NT, Mac, and Unix. When Microsoft bought OneTree in 1994, they immediately ceased development on all versions except for Windows. Microsoft SourceSafe 3.1, Windows 16-bit-only and Macintosh, rebranded One Tree 3.0 versions, were briefly available before Microsoft released ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
