Raw is a brand of the U. S. based professional wrestling promotion WWE. The brand was first established on March 25, 2002, during a special episode of Monday Night Raw and went into effect one week on April 1; the brand was discontinued for a period between August 2010 and July 2016. Wrestlers assigned to the Raw brand wrestle predominantly on the eponymous television program; the brand has appeared in the Worlds Collide and Mixed Match Challenge events. During the first brand split, they competed on their former supplementary show, Heat. In early-to-mid-2002 World Wrestling Federation underwent a process they called the "brand extension"; the WWF divided itself into two de facto wrestling promotions with separate rosters and authority figures. Raw and SmackDown! would host each division, give its name to the division and compete against each other. The split came about as a result of the WWF purchasing their two biggest competitors, World Championship Wrestling and Extreme Championship Wrestling.
The brand extension was publicly announced by Linda McMahon during a telecast of Raw on March 25 and became official the next day. At the time, this excluded the WWE Undisputed Championship and the WWE Women's Championship as those WWE titles would be defended on both shows. In September 2002 WWE Undisputed Champion Brock Lesnar refused to defend the title on Raw, in effect causing his title to become exclusive to SmackDown; the following week on Raw, Raw General Manager Eric Bischoff awarded a newly instated World Heavyweight Championship to Raw's designated number one contender Triple H. Because the WWE Undisputed Championship was now a SmackDown exclusive, it was no longer referred to as "undisputed". Following this, the Women's Championship soon became a Raw exclusive as well; as a result of the brand extension, an annual "draft lottery" was instituted to exchange members of each roster and refresh the lineups. Raw was the home brand for many top WWE stars including Triple H, Ric Flair, Randy Orton, Chris Benoit, Chris Jericho, Shawn Michaels, Trish Stratus, Stacy Keibler.
The 2005 draft was held on the June 6 episode of Raw. The first draft lottery pick was WWE Champion John Cena, thus moving the WWE Championship to Raw and having two titles on the brand. World Heavyweight Champion Batista was drafted to SmackDown as the last draft pick, leaving only the WWE Championship on Raw. On the 2008 draft lottery, CM Punk got drafted to Raw and won the World Heavyweight Championship from Edge, a SmackDown wrestler. Triple H, the WWE Champion at the time, got drafted to SmackDown while Kane, the ECW Champion, got drafted to Raw. After the draft lottery in 2009, the WWE Championship was brought back to Raw when Triple H was drafted from SmackDown while the World Heavyweight Championship was brought back to SmackDown when Edge defeated John Cena to win the title at Backlash. On the August 29, 2011, episode of Raw, it was announced that performers from Raw and SmackDown were no longer exclusive to their respective brand. Subsequently, championships exclusive to one show or the other were available for wrestlers from any show to compete for—this would mark the end of the brand extension as all programming and live events featured the full WWE roster.
In a 2013 interview with Advertising Age, Stephanie McMahon explained that WWE's decision to end the brand extension was due to wanting their content to flow across television and online platforms. On May 25, 2016, it was announced that WWE would be reintroducing the brand split in July, with distinctive rosters for both Raw and SmackDown. On the July 11 episode of Raw, Vince McMahon named Stephanie McMahon the commissioner of Raw; the draft took place on the live premiere of SmackDown Live on July 19, with the general managers of the respective brands hand-picking the wrestlers for their brands. Raw's Commissioner Stephanie McMahon and General Manager Mick Foley created a new championship—the WWE Universal Championship; this championship would be exclusive to the Raw brand, as the WWE World Championship had become exclusive to the SmackDown brand. Clash of Champions was scheduled as the first Raw-exclusive pay-per-view since January 2007 and the reintroduction of the Cruiserweight division where as Elimination Chamber has been scheduled as final Raw-exclusive pay-per-view making upcomings to be interbranded after WrestleMania.
The Undisputed WWE Championship and the original WWE Women's Championship were available to both brands. The other championships were exclusive to the brand; when the brand extension began, Raw received the Intercontinental Championship and European Championship when their respective holders were drafted. In September 2002, the WWE Undisputed Championship became the WWE Championship again and was moved to SmackDown, prompting Raw General Manager Eric Bischoff to create the World Heavyweight Championship for Raw. Shortly thereafter, Raw became the exclusive brand for the World Tag Team Championships, the Intercontinental Championship and the WWE Women's Championship. On July 19, 2016, the brand extension was brought back and for the first time the draft was held on SmackDown Live. Raw drafted the WWE Women's Championship, the United States Championship and the WWE Tag Team Champions. With the WWE Championship being defended on SmackDown, Stephanie McMahon and Mick Foley introduced the Universal Championship
Double compare-and-swap is an atomic primitive proposed to support certain concurrent programming techniques. DCAS takes two not contiguous memory locations and writes new values into them only if they match pre-supplied "expected" values. DCAS is sometimes confused with the double-width compare-and-swap implemented by instructions such as x86 CMPXCHG16B. DCAS, as discussed here, handles two discontiguous memory locations of pointer size, whereas DWCAS handles two adjacent pointer-sized memory locations. In his doctoral thesis, Michael Greenwald recommended adding DCAS to modern hardware, showing it could be used to create easy-to-apply yet efficient software transactional memory. Greenwald points out that an advantage of DCAS vs CAS is that higher-order CASn can be implemented in O with DCAS, but requires O time with unary CAS, where p is the number of contending processes. One of the advantages of DCAS is the ability to implement atomic deques with relative ease. More however, it has been shown that an STM can be implemented with comparable properties using only CAS.
In general however, DCAS is not a silver bullet: implementing lock-free and wait-free algorithms using it is just as complex and error-prone as for CAS. Motorola at one point included DCAS in the instruction set for its 68k series; as of 2015, DCAS is not natively supported by any widespread CPUs in production. The generalization of DCAS to more than two addresses is sometimes called MCAS. MCAS can be implemented in software in various ways. In 2013, Trevor Brown, Faith Ellen, Eric Ruppert have implemented in software a multi-address LL/SC extension that while being more restrictive than MCAS enabled them, via some automated code generation, to implement one of the best performing concurrent binary search tree beating the JDK CAS-based skip list implementation. In general, DCAS can be provided by a more expressive hardware transactional memory. IBM POWER8 and Intel Intel TSX provide working implementations of transactional memory. Sun's cancelled Rock processor would have supported it as well.
US Patent 4584640 Method and apparatus for a compare and swap instruction Phuong Ha-Hoai. "Fast and Lock-free: Multi-word Compare-and-swap Algorithms". CiteSeerX 10.1.1.66.3324