mirror of
git://sourceware.org/git/newlib-cygwin.git
synced 2025-01-19 12:59:21 +08:00
8ca713d70a
When a reader opens, it needs to block if there are no writers open (unless is is opened with O_NONBLOCK). This is easy for the first reader to test, since it can just wait for a writer to signal that it is open (via the write_ready event). But when a second reader wants to open, all writers might have closed. To check this, use a new '_nwriters' member of struct fifo_shmem_t, which keeps track of the number of open writers. This should be more reliable than the previous method. Add nwriters_lock to control access to shmem->_nwriters, and remove reader_opening_lock, which is no longer needed. Previously only readers had access to the shared memory, but now writers access it too so that they can increment _nwriters during open/dup/fork/exec and decrement it during close. Add an optional 'only_open' argument to create_shmem for use by writers, which only open the shared memory rather than first trying to create it. Since writers don't need to access the shared memory until they have successfully connected to a pipe instance, they can safely assume that a reader has already created the shared memory. For debugging purposes, change create_shmem to return 1 instead of 0 when a reader successfully opens the shared memory after finding that it had already been created. Remove check_write_ready_evt, write_ready_ok_evt, and check_write_ready(), which are no longer needed. When opening a writer and looping to try to get a connection, recheck read_ready at the top of the loop since the number of readers might have changed. To slightly speed up the process of opening the first reader, take ownership immediately rather than waiting for the fifo_reader_thread to handle it.
README for GNU development tools This directory contains various GNU compilers, assemblers, linkers, debuggers, etc., plus their support routines, definitions, and documentation. If you are receiving this as part of a GDB release, see the file gdb/README. If with a binutils release, see binutils/README; if with a libg++ release, see libg++/README, etc. That'll give you info about this package -- supported targets, how to use it, how to report bugs, etc. It is now possible to automatically configure and build a variety of tools with one command. To build all of the tools contained herein, run the ``configure'' script here, e.g.: ./configure make To install them (by default in /usr/local/bin, /usr/local/lib, etc), then do: make install (If the configure script can't determine your type of computer, give it the name as an argument, for instance ``./configure sun4''. You can use the script ``config.sub'' to test whether a name is recognized; if it is, config.sub translates it to a triplet specifying CPU, vendor, and OS.) If you have more than one compiler on your system, it is often best to explicitly set CC in the environment before running configure, and to also set CC when running make. For example (assuming sh/bash/ksh): CC=gcc ./configure make A similar example using csh: setenv CC gcc ./configure make Much of the code and documentation enclosed is copyright by the Free Software Foundation, Inc. See the file COPYING or COPYING.LIB in the various directories, for a description of the GNU General Public License terms under which you can copy the files. REPORTING BUGS: Again, see gdb/README, binutils/README, etc., for info on where and how to report problems.