Candidates are advised to read the guide lines. For reference use prescribed, recommended books and other source you may come across. Correct referencing carries 10 Marks.
You can help by adding to it. October CoW is also used in libraryapplication and system code. In multithreaded systems, COW can be implemented without the use of traditional locking and instead use compare-and-swap to increment or decrement the internal reference counter.
Since the original resource will never be altered, it can safely be copied by multiple threads after the reference count was increased without the need of performance-expensive locking such as mutexes.
If the reference counter turns 0, then by definition only 1 thread was holding a reference so the resource can safely be de-allocated from memory, again without the use of performance-expensive locking mechanisms. The benefit of not having to copy the resource and the resulting performance gain over traditional deep-copying will therefore be valid in both single- and multithreaded systems.
For example, strings and arrays are passed by reference, but when modified, they are duplicated if they have non-zero reference counts. This allows them to act as value types without the performance problems of copying on assignment or making them immutable.
Qt uses atomic compare-and-swap operations to increment or decrement the internal reference counter.
Since the copies are cheap, Qt types can often be safely used by multiple threads without the need of locking mechanisms such as mutexes. The benefits of CoW are thus valid in both single- and multithreaded systems.
Typically, the snapshots store only the modified data, and are stored close to the main array, so they are only a weak form of incremental backup and cannot substitute for a full backup.
When implementing snapshots, there are two techniques: The original storage is never modified.
When a write request is made, it is redirected away from the original data into a new storage area. CoW does two data writes compared to ROW's one; it is difficult to implement efficiently and thus used infrequently. The copy-on-write technique can be used to emulate a read-write storage on media that require wear leveling or are physically write once read many.
The qcow2 QEMU copy on write disk image format uses the copy-on-write technique to reduce disk image size.
In high-reliability software[ edit ] Phantom OS uses CoW at all levels, not just a database or file system. At any time, a computer running this system can fail, and then, when it starts again, the software and operating system resume operation.
Only small amounts of work can be lost. The basic approach is that all program data are kept in virtual memory. On some schedule, a summary of all software data are written to virtual memory, forming a log that tracks the current value and location of each value.
When the computer fails, a recent copy of the log and other data remain safe on disk. When operation resumes, operating system software reads the log to restore consistent copies of all the programs and data. This approach uses copy-on-write at all levels in all software, including in application software.
This requires support within the application programming language. In practice, Phantom OS permits only languages that generate Java byte codes.Therefore, at the end of your assignment you need a list of the materials you have used - a bibliography or a reference list.
There are many ways of writing a list of references - check with your department for specific information.
The most common system is called the Harvardsystem. There is no definitive version of the Harvard system and most . Reg. No.: //07 MAIN CAMPUS SMITH STREET DURBAN FACULTY OF INFORMATION TECHNOLOGY DIPLOMA IN INFORMATION TECHNOLOGY 1ST YEAR ACADEMIC YEAR ASSIGNMENT BOOKLET Registered with the Department of Education as a Private Higher Education Institution under the Higher Education Act, perlop.
NAME DESCRIPTION. Operator Precedence and Associativity Terms and List Operators (Leftward) The Arrow Operator Auto-increment and Auto-decrement.
The following overview should help you better understand how to cite sources using MLA eighth edition, including the list of works cited and in-text citations.
An assignment must describe the subject matter of the assignment; Notice to the obligor. There is no need for a specific language to make an assignment a valid one. We would like to show you a description here but the site won’t allow us.