WengQiang's Blog

linux_programming

发表于 2019-08-23 分类于 technique Waline：

select() int select(int nfds, fd_set *readfds, fd_set *writefds, fd_set *exceptfds, struct timeval *timeout);

poll()

int poll (struct pollfd *fds, unsigned int nfds, int timeout);

struct pollfd {
      int fd;
      short events; 
      short revents;
};

select() have three bitmask-based set of fds(fd-set), poll() only have signle array of fds(pollfd structure)
select() will reconstruct the fds, so should build each set before each call; poll() has seperate events and returned events, so it don't need.
select() and poll() manage everything in user mode and send sets each time to wait on, to add another fd we need to add it to the set and call select()/poll() again(); however epoll() use epoll_create to create context in the kernel mode, using epoll_ctl to update the context.

发表于 2019-03-28 更新于 2022-03-22 分类于 technique ，随笔 Waline：

ordering service: broadcast and establish concensus
identity and membership
scalable dissemination(optional): An optional peer-to-peer gossip service disseminates the blocks output by ordering service to all peers
smart-contract execution
ledger maintenance

client: submit transaction proposals and broadcast them
peer: execute transaction proposals and validate them and maintain blockchain ledger which is append-only not all peers will execute the transaciton proposals, which called endorsing peers execute them.
ordering service node

发表于 2019-03-08 更新于 2022-03-22 分类于 technique ，随笔 Waline：

introduction in general, on common processor machine, Integer multiplication is many times faster than division. So dividing a numerator n by a divisor d is mathematically equivalent to multiplication by the inverse of the divisor n / d = n * (1/d)
faster remainder algorithm for detail, see paperFaster Remainder by Direct Computation Applications to Compilers and Software Libraries

the faster remainder algorithm implemented in c is following(unsigned and signed):

发表于 2019-03-06 更新于 2022-03-22 分类于 technique ，随笔 Waline：

发表于 2019-03-01 更新于 2023-10-24 分类于 technique ，随笔 Waline：