Using directory approach
//----- BLOCK THIS FUNCTION BEING RUN SIMULTANEOUSLY ON DIFFERENT THREADS -----
//Creating and deleting a directory is a good way tot do this in PHP because although files may be opened by two different processes (which happily overwrite each other),
//directories don’t have such problems (they may be created and removed, but they can’t be written)
//We check for the presence of a directory by creating one. If the creation fails, then the directory is already there. If the creation succeed, then, the directory was not there.
if (mkdir('/tmp/mysemaphorefile.lock', 0700))
{
//We are OK to run
rmdir('/tmp/mysemaphorefile.lock') ;
}
else
{
//Another script is already running
}
USEFUL?
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