The fopen family of functions in C is normally used for reading configuration
files, since fgets is an easy way to parse files on a line-by-line basis.
The TSfopen family of functions aims at solving the same problem of buffered
IO and line at a time IO in a platform-independent manner. The fopen family
of C library functions can only open a file if a file descriptor less than
256 is available. Since Traffic Server often has more than 2000 file descriptors
open at once, however, the likelihood of an available file descriptor less
than 256 very small. To solve this problem, the TSfopen family can open
files with descriptors greater than 256.
The TSfopen family of routines is not intended for high speed IO or flexibility -
they are blocking APIs (not asynchronous). For performance reasons, you should
not directly use these APIs on a Traffic Server thread (when being called back
on an HTTP hook); it is better to use a separate thread for doing the blocking
IO. The TSfopen family is intended for reading and writing configuration
information when corresponding usage of the fopen family of functions is
inappropriate due to file descriptor and portability limitations. The TSfopen
family of functions consists of the following: