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Epoll
epoll is a Linux kernel system call for a scalable I/O event notification mechanism, first introduced in version 2.5.45 of the Linux kernel. Its function is to monitor multiple file descriptors to see whether I/O is possible on any of them. It is meant to replace the older POSIX select(2) and poll(2) system calls, to achieve better performance in more demanding applications, where the number of watched file descriptors is large (unlike the older system calls, which operate in ''O''(''n'') time, epoll operates in ''O''(1) time). epoll is similar to FreeBSD's kqueue, in that it consists of a set of user-space functions, each taking a file descriptor argument denoting the configurable kernel object, against which they cooperatively operate. epoll uses a red–black tree (RB-tree) data structure to keep track of all file descriptors that are currently being monitored. API int epoll_create1(int flags); Creates an epoll object and returns its file descriptor. The flags parameter al ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
File Descriptor
In Unix and Unix-like computer operating systems, a file descriptor (FD, less frequently fildes) is a process-unique identifier (handle) for a file or other input/output resource, such as a pipe or network socket. File descriptors typically have non-negative integer values, with negative values being reserved to indicate "no value" or error conditions. File descriptors are a part of the POSIX API. Each Unix process (except perhaps daemons) should have three standard POSIX file descriptors, corresponding to the three standard streams: Overview In the traditional implementation of Unix, file descriptors index into a per-process maintained by the kernel, that in turn indexes into a system-wide table of files opened by all processes, called the . This table records the ''mode'' with which the file (or other resource) has been opened: for reading, writing, appending, and possibly other modes. It also indexes into a third table called the inode table that describes the ac ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Kqueue
Kqueue is a scalable event notification interface introduced in FreeBSD 4.1 in July 2000, also supported in NetBSD, OpenBSD, DragonFly BSD, and macOS. Kqueue was originally authored in 2000 by Jonathan Lemon, then involved with the FreeBSD Core Team. Kqueue makes it possible for software like nginx to solve the c10k problem. The term "kqueue" refers to its function as a "kernel event queue" Kqueue provides efficient input and output event pipelines between the kernel and userland. Thus, it is possible to modify event filters as well as receive pending events while using only a single system call to kevent(2) per main event loop iteration. This contrasts with older traditional polling system calls such as poll(2) and select(2) which are less efficient, especially when polling for events on numerous file descriptors. Kqueue not only handles file descriptor events but is also used for various other notifications such as file modification monitoring, signals, asynchronous I ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Red–black Tree
In computer science, a red–black tree is a self-balancing binary search tree data structure noted for fast storage and retrieval of ordered information. The nodes in a red-black tree hold an extra "color" bit, often drawn as red and black, which help ensure that the tree is always approximately balanced. When the tree is modified, the new tree is rearranged and "repainted" to restore the coloring properties that constrain how unbalanced the tree can become in the worst case. The properties are designed such that this rearranging and recoloring can be performed efficiently. The (re-)balancing is not perfect, but guarantees searching in O(\log n) time, where n is the number of entries in the tree. The insert and delete operations, along with tree rearrangement and recoloring, also execute in O(\log n) time. Tracking the color of each node requires only one bit of information per node because there are only two colors (due to memory alignment present in some programming languag ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Kqueue
Kqueue is a scalable event notification interface introduced in FreeBSD 4.1 in July 2000, also supported in NetBSD, OpenBSD, DragonFly BSD, and macOS. Kqueue was originally authored in 2000 by Jonathan Lemon, then involved with the FreeBSD Core Team. Kqueue makes it possible for software like nginx to solve the c10k problem. The term "kqueue" refers to its function as a "kernel event queue" Kqueue provides efficient input and output event pipelines between the kernel and userland. Thus, it is possible to modify event filters as well as receive pending events while using only a single system call to kevent(2) per main event loop iteration. This contrasts with older traditional polling system calls such as poll(2) and select(2) which are less efficient, especially when polling for events on numerous file descriptors. Kqueue not only handles file descriptor events but is also used for various other notifications such as file modification monitoring, signals, asynchronous I ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Select (Unix)
is a system call and application programming interface (API) in Unix-like and POSIX-compliant operating systems for examining the status of file descriptors of open input/output channels. The select system call is similar to the ' facility introduced in UNIX System V and later operating systems. However, with the c10k problem, both select and poll have been superseded by the likes of kqueue, epoll, /dev/poll and I/O completion ports. One common use of select outside of its stated use of waiting on filehandles is to implement a portable sub-second sleep. This can be achieved by passing NULL for all three fd_set arguments, and the duration of the desired sleep as the timeout argument. In the C programming language, the select system call is declared in the header file sys/select.h or unistd.h, and has the following syntax: int select(int nfds, fd_set *readfds, fd_set *writefds, fd_set *errorfds, struct timeval *timeout); fd_set type arguments may be manipulated with fou ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Input/output Completion Port
Input/output completion port (IOCP) is an API for performing multiple simultaneous asynchronous input/output operations in Windows NT versions 3.5 and later, AIX and on Solaris 10 and later. An input/output completion port object is created and associated with a number of sockets or file handles. When I/O services are requested on the object, completion is indicated by a message A message is a unit of communication that conveys information from a sender to a receiver. It can be transmitted through various forms, such as spoken or written words, signals, or electronic data, and can range from simple instructions to co ... queued to the I/O completion port. A process requesting I/O services is not notified of completion of the I/O services, but instead checks the I/O completion port's message queue to determine the status of its I/O requests. The I/O completion port manages multiple threads and their concurrency. See also * Overlapped I/O * kqueue * epoll References E ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Libevent
libevent is a software library that provides asynchronous event notification. The libevent API provides a mechanism to execute a callback function when a specific event occurs on a file descriptor or after a timeout has been reached. libevent also supports callbacks triggered by signals and regular timeouts. libevent is meant to replace the event loop found in event-driven network servers. An application can just call event_dispatch() and then add or remove events dynamically without having to change the event loop. Currently, libevent supports /dev/poll, kqueue(2), POSIX select(2), Windows IOCP, poll(2), epoll(7) and Solaris event ports. It also has experimental support for real-time signals. The exposed event API is uniform over all of the supported platforms. As a result, libevent allows for portable application development and provides "the most scalable event notification mechanism available on an operating system". Using callbacks on signals, libevent makes ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Input/output Completion Port
Input/output completion port (IOCP) is an API for performing multiple simultaneous asynchronous input/output operations in Windows NT versions 3.5 and later, AIX and on Solaris 10 and later. An input/output completion port object is created and associated with a number of sockets or file handles. When I/O services are requested on the object, completion is indicated by a message A message is a unit of communication that conveys information from a sender to a receiver. It can be transmitted through various forms, such as spoken or written words, signals, or electronic data, and can range from simple instructions to co ... queued to the I/O completion port. A process requesting I/O services is not notified of completion of the I/O services, but instead checks the I/O completion port's message queue to determine the status of its I/O requests. The I/O completion port manages multiple threads and their concurrency. See also * Overlapped I/O * kqueue * epoll References E ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Linux Kernel
The Linux kernel is a Free and open-source software, free and open source Unix-like kernel (operating system), kernel that is used in many computer systems worldwide. The kernel was created by Linus Torvalds in 1991 and was soon adopted as the kernel for the GNU operating system (OS) which was created to be a free software, free replacement for Unix. Since the late 1990s, it has been included in many Linux distributions, operating system distributions, many of which are called Linux. One such Linux kernel operating system is Android (operating system), Android which is used in many mobile and embedded devices. Most of the kernel code is written in C (programming language), C as supported by the GNU compiler collection (GCC) which has extensions beyond standard C. The code also contains assembly language, assembly code for architecture-specific logic such as optimizing memory use and task execution. The kernel has a Modular programming, modular design such that modules can be inte ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Events (computing)
Event may refer to: Gatherings of people * Ceremony, an event of ritual significance, performed on a special occasion * Convention (meeting), a gathering of individuals engaged in some common interest * Event management, the organization of events * Festival, an event that celebrates some unique aspect of a community * Happening, a type of artistic performance * Media event, an event created for publicity * Party, a social, recreational or corporate events held * Sporting event, at which athletic competition takes place * Virtual event, a gathering of individuals within a virtual environment Science, technology, and mathematics * Event (computing), a software message indicating that something has happened, such as a keystroke or mouse click * Event (philosophy), an object in time, or an instantiation of a property in an object * Event (probability theory), a set of outcomes to which a probability is assigned * Event (relativity), a point in space at an instant in time, i.e. a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
YouTube
YouTube is an American social media and online video sharing platform owned by Google. YouTube was founded on February 14, 2005, by Steve Chen, Chad Hurley, and Jawed Karim who were three former employees of PayPal. Headquartered in San Bruno, California, it is the second-most-visited website in the world, after Google Search. In January 2024, YouTube had more than 2.7billion monthly active users, who collectively watched more than one billion hours of videos every day. , videos were being uploaded to the platform at a rate of more than 500 hours of content per minute, and , there were approximately 14.8billion videos in total. On November 13, 2006, YouTube was purchased by Google for $1.65 billion (equivalent to $ billion in ). Google expanded YouTube's business model of generating revenue from advertisements alone, to offering paid content such as movies and exclusive content produced by and for YouTube. It also offers YouTube Premium, a paid subs ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Event Port
Event may refer to: Gatherings of people * Ceremony, an event of ritual significance, performed on a special occasion * Convention (meeting), a gathering of individuals engaged in some common interest * Event management, the organization of events * Festival, an event that celebrates some unique aspect of a community * Happening, a type of artistic performance * Media event, an event created for publicity * Party, a social, recreational or corporate events held * Sporting event, at which athletic competition takes place * Virtual event, a gathering of individuals within a virtual environment Science, technology, and mathematics * Event (computing), a software message indicating that something has happened, such as a keystroke or mouse click * Event (philosophy), an object in time, or an instantiation of a property in an object * Event (probability theory), a set of outcomes to which a probability is assigned * Event (relativity), a point in space at an instant in time, i.e. a lo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
