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authorZac Medico <zmedico@gentoo.org>2011-03-17 14:12:13 -0700
committerZac Medico <zmedico@gentoo.org>2011-03-18 12:50:14 -0700
commit768958c9d1504f72d2f252c1793a5bc48a2a4a85 (patch)
treeb5d66a46683197736331029a4b1da01a4a66f407 /bin
parentf72d4b20478a33da08dd30f399b3a55cc7a9dda4 (diff)
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ebuild-ipc: use non-blocking read
This makes it possible for the daemon to send a reply without blocking, thereby improving performance and also making it possible for the daemon to do a non-blocking write without a race condition. This reverts part of commit 81fc303212b8379219cf5d463c8717359b972dba, which probably didn't help portability anyway. Now, ebuild-ipc is using non-blocking read with os.read and EAGAIN handling, just like EbuildIpcDaemon since commit 7e5b81da12dd7bd59f6620840dc0d824e3f4d69a (known compatible with FreeBSD).
Diffstat (limited to 'bin')
-rwxr-xr-xbin/ebuild-ipc.py54
1 files changed, 41 insertions, 13 deletions
diff --git a/bin/ebuild-ipc.py b/bin/ebuild-ipc.py
index d8e7e5512..cb77171ec 100755
--- a/bin/ebuild-ipc.py
+++ b/bin/ebuild-ipc.py
@@ -134,23 +134,43 @@ class EbuildIpc(object):
return os.WEXITSTATUS(wait_retval[1])
- def _receive_reply(self):
+ def _receive_reply(self, input_fd):
- # File streams are in unbuffered mode since we do atomic
- # read and write of whole pickles.
- input_file = open(self.ipc_out_fifo, 'rb', 0)
-
- # For maximum portability, use a single atomic read.
+ # Timeouts are handled by the parent process, so just
+ # block until input is available. For maximum portability,
+ # use a single atomic read.
buf = None
- try:
- buf = input_file.read(self._BUFSIZE)
- except IOError as e:
- if not buf:
+ while True:
+ try:
+ events = select.select([input_fd], [], [])
+ except select.error as e:
portage.util.writemsg_level(
- "ebuild-ipc: %s\n" % (e,),
+ "ebuild-ipc: %s: %s\n" % \
+ (portage.localization._('during select for read'), e),
level=logging.ERROR, noiselevel=-1)
+ continue
- input_file.close()
+ if events[0]:
+ # For maximum portability, use os.read() here since
+ # array.fromfile() and file.read() are both known to
+ # erroneously return an empty string from this
+ # non-blocking fifo stream on FreeBSD (bug #337465).
+ try:
+ buf = os.read(input_fd, self._BUFSIZE)
+ except OSError as e:
+ if e.errno != errno.EAGAIN:
+ portage.util.writemsg_level(
+ "ebuild-ipc: %s: %s\n" % \
+ (portage.localization._('read error'), e),
+ level=logging.ERROR, noiselevel=-1)
+ break
+ # Assume that another event will be generated
+ # if there's any relevant data.
+ continue
+
+ # Only one (atomic) read should be necessary.
+ if buf:
+ break
retval = 2
@@ -192,6 +212,13 @@ class EbuildIpc(object):
self._no_daemon_msg()
return 2
+ # Open the input fifo before the output fifo, in order to make it
+ # possible for the daemon to send a reply without blocking. This
+ # improves performance, and also makes it possible for the daemon
+ # to do a non-blocking write without a race condition.
+ input_fd = os.open(self.ipc_out_fifo,
+ os.O_RDONLY|os.O_NONBLOCK)
+
# Use forks so that the child process can handle blocking IO
# un-interrupted, while the parent handles all timeout
# considerations. This helps to avoid possible race conditions
@@ -231,12 +258,13 @@ class EbuildIpc(object):
if pid == 0:
os.close(pr)
- retval = self._receive_reply()
+ retval = self._receive_reply(input_fd)
os._exit(retval)
os.close(pw)
retval = self._wait(pid, pr, portage.localization._('during read'))
os.close(pr)
+ os.close(input_fd)
return retval
def ebuild_ipc_main(args):