Now here’s a happy sign that summer is almost upon us: Brooklyn Pigfest, the annual Dumbo day of whole-hog feasting, is tomorrow. The event, which is being held in the roofless Tobacco Building, underneath the Manhattan Bridge, from 1 p.m. to 6 p.m., gets bigger every year, and it’s not hard to see why: It’s one of the only places in the city where you can eat a full-size barbecued pig, not an insipid, frighteningly vulnerable-looking piglet, as at most restaurants. And between the live band, the Brooklyn Brewery beer on tap, and the sun-dappled setting, there are plenty of other reasons to go. But the pig is the main thing, and visitors have cause to worry if there’s enough to go around. Last year, Brooklyn Pigfest ran out of pig midway through the event, which made for a lot of not-very-happy picnickers. While it lasts, though, it’s bound to be good, cooked as it is every year by Sam Barbieri and Ralph Yedinak from the Waterfront Ale House, the city’s most unheralded barbecuers. Tickets are available, for $85 a person, at the Brooklyn Brewery Website.