| pico_thread |
| |
| bsy@cs.ucsd.edu |
| Mar, 1996 |
| |
| This is a portable, machine independent coroutine threads package. It |
| was written in 1994 while I was a graduate student at Carnegie Mellon. |
| In 1996, I added the pico_select interface to integrate in I/O |
| operations because I wanted to build a coroutine based Web server. |
| |
| The portability of this coroutine package stems from its design around |
| the ubiquitious setjmp/longjmp primitives, which suffices for the |
| basic context-switching needed by coroutine threads. The only machine |
| (operating system, really) dependency is whether POSIX style signals |
| are supported, or whether pre-4.4 Berkeley style signals are provided; |
| and whether POSIX style setjmp (vs sigsetjmp) are provided, or whether |
| Berkeley _setjmp (vs setjmp) are to be used. Knowledge about signals |
| is needed since pico_thread blocks signals while it is doing its |
| bookkeeping and while it is context switching between threads to hide |
| the threading details from user-supplied signal handlers. |
| |
| TO DO |
| |
| A complete, transparent, and stackable syscall emulation library (as |
| an separate layer, not integrated into pico_thread since it may not be |
| desired) to make writing coroutine threads easier. |
| |
| Preemption via interval timer clocks. |
| |
| Stack usage estimates; stack overflow panics. |
| |
| Complete the pico_io interface to provide stdio-like I/O which uses |
| pico_select internally to permit threads to perform (disjoint) I/O |
| operations. |
