Luanda - Angolan President Jose Eduardo Dos Santos, in power since 1979, will not contest Wednesday's general election, meaning he will soon lose his place as Africa's second longest-serving leader.The continent is home to many men who have held office for two decades or more, and Dos Santos has up to now trailed Teodoro Obiang Nguema of Equatorial Guinea by just a month.Here is a rundown:More than 30 years - In tiny, oil-rich Equatorial Guinea, Obiang is Africa's longest-serving leader, at 38 years.Obiang came to power in a coup on August 3, 1979, ousting his own uncle, Francisco Macias Nguema, who was shot by a firing squad. Obiang was re-elected in 2016 for a fifth seven-year term.- Robert Mugabe, 93, is the oldest serving head of state in the world, having run Zimbabwe since its independence in April 1980.Mugabe has been either prime minister or president (since 1987) for more than 37 years.- In Cameroon, Paul Biya has nearly 35 years under his belt. He became president on November 6, 1982 after serving seven years as prime minister.- Congolese President Denis Sassou Nguesso has spent 33 years in office, but not in one go. He first served from 1979 to 1992 and then came back to run the country in 1997 at the end of a civil war.Sassou Nguesso was re-elected in March 2016 and could run again when his current term expires.- In Uganda, Yoweri Museveni has been in power for more than 31 years. He took office in January 1986 after winning the war that ousted Idi Amin Dada, with help from neighbouring Tanzania.He was elected to a fifth term in February 2016 amid allegations of fraud.- King Mswati III of Swaziland is Africa's last absolute monarch and has served for more than 31 years. He acceded to the throne of the tiny southern kingdom in April 1986. More than 20 years - In Sudan, Omar al-Bashir has ruled for 28 years since he staged a successful coup in June 1989.- Chad's leader Idriss Deby took over the north-central African nation in December 1990, giving him nearly 27 years in power. Deby won a disputed fifth term in April 2016- Eritrea's head of state Isaias Afewerki has been around since 1993. All time record - The record for political longevity on the African continent is held by Ethiopian emperor Haile Selassie, ousted in 1974 after a reign of 44 years.- Libya's Moammar Gaddafi, who ruled Libya with an iron grip for nearly 42 years, was slain on October 20, 2011 after a protest movement turned into an armed conflict.- Gabon's Omar Bongo Ondimba died in June 2009 after more than 41 years in power.