From 09b727836fce66a69dd517c0d78334101a896c3b Mon Sep 17 00:00:00 2001
From: Michael Hanselmann <hansmi@google.com>
Date: Fri, 9 Nov 2012 16:12:22 +0100
Subject: [PATCH] RunCmd: Expose "postfork" callback
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The β_postfork_fnβ parameter was only used for tests until now. To
implement a good locking scheme, remote commands must also make use of
this callback to release a lock when the command was successfully
started (but did not yet finish).
Signed-off-by: Michael Hanselmann <hansmi@google.com>
Reviewed-by: Guido Trotter <ultrotter@google.com>
---
lib/utils/process.py | 24 +++++++++++++-----------
test/ganeti.utils.process_unittest.py | 8 ++++----
2 files changed, 17 insertions(+), 15 deletions(-)
diff --git a/lib/utils/process.py b/lib/utils/process.py
index 243151f32..cc1c9ed06 100644
--- a/lib/utils/process.py
+++ b/lib/utils/process.py
@@ -142,7 +142,7 @@ def _BuildCmdEnvironment(env, reset):
def RunCmd(cmd, env=None, output=None, cwd="/", reset_env=False,
interactive=False, timeout=None, noclose_fds=None,
- input_fd=None, _postfork_fn=None):
+ input_fd=None, postfork_fn=None):
"""Execute a (shell) command.
The command should not read from its standard input, as it will be
@@ -172,7 +172,8 @@ def RunCmd(cmd, env=None, output=None, cwd="/", reset_env=False,
open for the child process
@type input_fd: C{file}-like object or numeric file descriptor
@param input_fd: File descriptor for process' standard input
- @param _postfork_fn: Callback run after fork but before timeout (unittest)
+ @type postfork_fn: Callable receiving PID as parameter
+ @param postfork_fn: Callback run after fork but before timeout
@rtype: L{RunResult}
@return: RunResult instance
@raise errors.ProgrammerError: if we call this when forks are disabled
@@ -211,10 +212,11 @@ def RunCmd(cmd, env=None, output=None, cwd="/", reset_env=False,
out, err, status, timeout_action = _RunCmdPipe(cmd, cmd_env, shell, cwd,
interactive, timeout,
noclose_fds, input_fd,
- _postfork_fn=_postfork_fn)
+ postfork_fn=postfork_fn)
else:
- assert _postfork_fn is None, \
- "_postfork_fn not supported if output provided"
+ if postfork_fn:
+ raise errors.ProgrammerError("postfork_fn is not supported if output"
+ " should be captured")
assert input_fd is None
timeout_action = _TIMEOUT_NONE
status = _RunCmdFile(cmd, cmd_env, shell, output, cwd, noclose_fds)
@@ -490,9 +492,8 @@ def _WaitForProcess(child, timeout):
def _RunCmdPipe(cmd, env, via_shell, cwd, interactive, timeout, noclose_fds,
- input_fd,
- _linger_timeout=constants.CHILD_LINGER_TIMEOUT,
- _postfork_fn=None):
+ input_fd, postfork_fn=None,
+ _linger_timeout=constants.CHILD_LINGER_TIMEOUT):
"""Run a command and return its output.
@type cmd: string or list
@@ -512,7 +513,8 @@ def _RunCmdPipe(cmd, env, via_shell, cwd, interactive, timeout, noclose_fds,
open for the child process
@type input_fd: C{file}-like object or numeric file descriptor
@param input_fd: File descriptor for process' standard input
- @param _postfork_fn: Function run after fork but before timeout (unittest)
+ @type postfork_fn: Callable receiving PID as parameter
+ @param postfork_fn: Function run after fork but before timeout
@rtype: tuple
@return: (out, err, status)
@@ -548,8 +550,8 @@ def _RunCmdPipe(cmd, env, via_shell, cwd, interactive, timeout, noclose_fds,
cwd=cwd,
preexec_fn=preexec_fn)
- if _postfork_fn:
- _postfork_fn(child.pid)
+ if postfork_fn:
+ postfork_fn(child.pid)
out = StringIO()
err = StringIO()
diff --git a/test/ganeti.utils.process_unittest.py b/test/ganeti.utils.process_unittest.py
index 322d74235..f3fbce66a 100755
--- a/test/ganeti.utils.process_unittest.py
+++ b/test/ganeti.utils.process_unittest.py
@@ -155,7 +155,7 @@ class TestIsProcessHandlingSignal(unittest.TestCase):
class _PostforkProcessReadyHelper:
- """A helper to use with _postfork_fn in RunCmd.
+ """A helper to use with C{postfork_fn} in RunCmd.
It makes sure a process has reached a certain state by reading from a fifo.
@@ -264,7 +264,7 @@ class TestRunCmd(testutils.GanetiTestCase):
(self.proc_ready_helper.write_fd, self.fifo_file))
result = utils.RunCmd(["/bin/sh", "-c", cmd], timeout=0.2,
noclose_fds=[self.proc_ready_helper.write_fd],
- _postfork_fn=self.proc_ready_helper.Ready)
+ postfork_fn=self.proc_ready_helper.Ready)
self.assertEqual(result.exit_code, 0)
def testTimeoutKill(self):
@@ -276,7 +276,7 @@ class TestRunCmd(testutils.GanetiTestCase):
timeout, [self.proc_ready_helper.write_fd],
None,
_linger_timeout=0.2,
- _postfork_fn=self.proc_ready_helper.Ready)
+ postfork_fn=self.proc_ready_helper.Ready)
self.assert_(status < 0)
self.assertEqual(-status, signal.SIGKILL)
@@ -285,7 +285,7 @@ class TestRunCmd(testutils.GanetiTestCase):
(self.proc_ready_helper.write_fd, self.fifo_file))
result = utils.RunCmd(["/bin/sh", "-c", cmd], timeout=0.2,
noclose_fds=[self.proc_ready_helper.write_fd],
- _postfork_fn=self.proc_ready_helper.Ready)
+ postfork_fn=self.proc_ready_helper.Ready)
self.assert_(result.failed)
self.assertEqual(result.stdout, "sigtermed\n")
--
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