fast producer / slow consumer in C
c, c++, linux, unix
Solution
You should return the code to its original form — that is, a single program calling a second program — except that you replace the `system(3)` call with a `popen(3)` call. Now the calling program can interleave calls for event checking with reading lines from the external program.
The Unix pipe mechanism ensures that a slow consumer will cause the fast producer to wait while writing when the pipe gets full.
You might also want to look into the `fileno(3)` function, combined with `select(2)` or `poll(2)` in order to make reading from the external program asynchronous, so that it can never block the calling program.
Problem
I wrote a program in C that waits for an event, and then run an external system command by `system()` function. ``` while( true ){ wait_for_event(); system("cmd"); } ``` I have a seriuos problem on this, The `cmd` is a heavy command and takes several seconds to be completed, my app misses some events in this time frame. So I decided to move the `system` function, which is very heavy, to another program, So I changed my program as follows: ``` while( true ){ wait_for_event(); write_to_fifo("cmd"); } ``` and wrote another program: ``` while(true){ system(read_from_pipe()); } ``` but it doesn't help, because if producer (1st program) writes faster than consumer (2nd program), then consumer misses some data! Is there any way to handle this problem?