aio: add generic thread-pool facility

Add a generic thread-pool.  The code is roughly based on posix-aio-compat.c,
with some changes, especially the following:

- use QemuSemaphore instead of QemuCond;

- separate the state of the thread from the return code of the worker
function.  The return code is totally opaque for the thread pool;

- do not busy wait when doing cancellation.

A more generic threadpool (but still specific to I/O so that in the future
it can use special scheduling classes or PI mutexes) can have many uses:
it allows more flexibility in raw-posix.c and can more easily be extended
to Win32, and it will also be used to do an msync of the persistent bitmap.

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

1 files changed, 1 insertions, 1 deletions

diff --git a/Makefile.objs b/Makefile.objs
index a8ade04c02..f8ae0316b8 100644
--- a/Makefile.objs
+++ b/Makefile.objs
@@ -43,7 +43,7 @@ coroutine-obj-$(CONFIG_WIN32) += coroutine-win32.o
 
 block-obj-y = iov.o cache-utils.o qemu-option.o module.o async.o
 block-obj-y += nbd.o block.o blockjob.o aes.o qemu-config.o
-block-obj-y += qemu-progress.o qemu-sockets.o uri.o notify.o
+block-obj-y += thread-pool.o qemu-progress.o qemu-sockets.o uri.o notify.o
 block-obj-y += $(coroutine-obj-y) $(qobject-obj-y) $(version-obj-y)
 block-obj-$(CONFIG_POSIX) += posix-aio-compat.o
 block-obj-$(CONFIG_POSIX) += event_notifier-posix.o aio-posix.o