change to use expoential function to generate delay time. add fuzz method
change to use expoential function to generate delay time.
add fuzz method

RyanTech/tchannel,benfleis/tchannel,RyanTech/tchannel,chenwenbin928/tchannel,savaki/tchannel,vanloswang/tchannel,RyanTech/tchannel,Zirpon/tchannel,sasa233/tchannel,savaki/tchannel,savaki/tchannel,bunnyblue/tchannel,bunnyblue/tchannel,sasa233/tchannel,vanloswang/tchannel,hustxiaoc/tchannel,benfleis/tchannel,i/tchannel,benfleis/tchannel,i/tchannel,hustxiaoc/tchannel,sasa233/tchannel,i/tchannel,bunnyblue/tchannel,Zirpon/tchannel,vanloswang/tchannel,Zirpon/tchannel,chenwenbin928/tchannel,hustxiaoc/tchannel,chenwenbin928/tchannel