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As the Autoconf documentation says, "These days portable programs [...] should not rely on `HAVE_RESTARTABLE_SYSCALLS', since nowadays whether a system call is restartable is a dynamic issue, not a configuration-time issue." In other words, if we ever rely on HAVE_RESTARTABLE_SYSCALLS, we are at the mercy of any code that Guile happens to be linked with, because that code could install a signal handler without the SA_RESTART flag, and then a Guile system call could unexpectedly return EINTR. The readline part of this goes back to this problem report: excellent example of the above paragraph. It was noted during the discussion that undefining HAVE_RESTARTABLE_SYSCALLS would fix the problem, but that solution wasn't adopted - I guess because Guile was still using cooperative threads then (not pthreads) and so there was a significant concern (whether founded or not) that not using restartable syscalls (where available) could lead to a loss of performance. Now Guile's default mode of operation is with pthreads, where we already don't assume that HAVE_RESTARTABLE_SYSCALLS is reliable, so there is no possible further performance loss. And in any case we really have no choice, if we want correct operation. * configure.in (AC_SYS_RESTARTABLE_SYSCALLS): Removed. * doc/ref/posix.texi (Signals): Remove statement that Guile always sets SA_RESTART flag. * guile-readline/configure.in (GUILE_SIGWINCH_SA_RESTART_CLEARED): Remove this setting, together with its test code. (HAVE_RL_PRE_INPUT_HOOK): Remove this setting and its code, as no longer needed. * guile-readline/readline.c (sigwinch_enable_restart): Removed. (scm_init_readline): Remove setting of rl_pre_input_hook. * libguile/_scm.h (SCM_SYSCALL): Remove the definition that relies on HAVE_RESTARTABLE_SYSCALLS. * libguile/scmsigs.c (scm_sigaction_for_thread): Don't always set the SA_RESTART flag if available. Update docstring accordingly. (scm_init_scmsigs): Remove code that sets SA_RESTART flag for all signals. |
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| .. | ||
| example-smob | ||
| goops | ||
| maint | ||
| r5rs | ||
| ref | ||
| sources | ||
| tutorial | ||
| .gitignore | ||
| BUGS | ||
| ChangeLog-2008 | ||
| ChangeLog-guile-doc | ||
| groupings.alist | ||
| guile-api.alist | ||
| guile.1 | ||
| hacks.el | ||
| Makefile.am | ||
| mbapi.texi | ||
| mltext.texi | ||
| NEWS | ||
| oldfmt.c | ||
| README | ||
| recipe-guidelines.txt | ||
| THANKS | ||
| use-cases.fig | ||
| use-cases.txt | ||
This directory contains documentation on the Guile core. -*-text-*- The documentation consists of the following manuals. - The Guile Tutorial (guile-tut.texi) contains a tutorial introduction to using Guile. - The Guile Reference Manual (guile.texi) contains (or is intended to contain) reference documentation on all aspects of Guile. - The GOOPS Manual (goops.texi) contains both tutorial-style and reference documentation for using GOOPS, Guile's Object Oriented Programming System. - The Revised^5 Report on the Algorithmic Language Scheme (r5rs.texi). Please be aware that this is all very much work in progress (apart from the Revised^5 Report). Bug reports and contributions are welcome! The file `oldfmt.c' contains a function which can be used by application writers to support both old-style and new-style error format strings. The `sources' directory includes some stuff relevant to the Guile reference manual, and which may eventually be folded in to it. It's not immediately relevant, however, which is why it's not in this directory. The Revised^4 Report (r4rs.texi) is no longer in this distribution, as it is completely superseded by the Revised^5 Report. If you need to consult R4RS, it is still widely available, for example at http://www-swiss.ai.mit.edu/projects/info/SchemeDocs/r4rs/.