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I would like to use gdb::parallel_for_each to implement the parallelism of the DWARF unit indexing. However, the existing implementation of gdb::parallel_for_each is blocking, which doesn't work with the model used by the DWARF indexer, which is asynchronous and callback-based. Add an asynchronouys version of gdb::parallel_for_each that will be suitable for this task. This new version accepts a callback that is invoked when the parallel for each is complete. This function uses the same strategy as gdb::task_group to invoke the "done" callback: worker threads have a shared_ptr reference to some object. The last worker thread to drop its reference causes the object to be deleted, which invokes the callback. Unlike for the sync version of gdb::parallel_for_each, it's not possible to keep any state in the calling thread's stack, because that disappears immediately after starting the workers. So all the state is kept in that same shared object. There is a limitation that the sync version doesn't have, regarding the arguments you can pass to the worker objects: it's not possibly to rely on references. There are more details in a comment in the code. It would be possible to implement the sync version of gdb::parallel_for_each on top of the async version, but I decided not to do it to avoid the unnecessary dynamic allocation of the shared object, and to avoid adding the limitations on passing references I mentioned just above. But if we judge that it would be an acceptable cost to avoid the duplication, we could do it. Add a self test for the new function. Change-Id: I6173defb1e09856d137c1aa05ad51cbf521ea0b0 Approved-By: Tom Tromey <tom@tromey.com>
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, and so on. 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.