log subprocess calls.

[nodemanager.git] / tools.py

diff --git a/tools.py b/tools.py
index 143e128..bc4b49e 100644 (file)
--- a/tools.py
+++ b/tools.py
@@ -1,15 +1,18 @@
+"""A few things that didn't seem to fit anywhere else."""
+
 import cPickle
 import errno
 import os
 import pwd
 import tempfile
 import threading
+import fcntl
+import commands
 
 import logger
 
 
-PID_FILE = '/var/run/pl_node_mgr.pid'
-
+PID_FILE = '/var/run/nm.pid'
 
 def as_daemon_thread(run):
     """Call function <run> with no arguments in its own thread."""
@@ -17,7 +20,6 @@ def as_daemon_thread(run):
     thr.setDaemon(True)
     thr.start()
 
-
 def close_nonstandard_fds():
     """Close all open file descriptors other than 0, 1, and 2."""
     _SC_OPEN_MAX = 4
@@ -25,7 +27,6 @@ def close_nonstandard_fds():
         try: os.close(fd)
         except OSError: pass  # most likely an fd that isn't open
 
-
 # after http://www.erlenstar.demon.co.uk/unix/faq_2.html
 def daemon():
     """Daemonize the current process."""
@@ -35,13 +36,11 @@ def daemon():
     os.chdir('/')
     os.umask(0)
     devnull = os.open(os.devnull, os.O_RDWR)
-    for fd in range(3): os.dup2(devnull, fd)
-
-
-def deepcopy(obj):
-    """Return a deep copy of obj."""
-    return cPickle.loads(cPickle.dumps(obj, -1))
-
+    os.dup2(devnull, 0)
+    # xxx fixme - this is just to make sure that nothing gets stupidly lost - should use devnull
+    crashlog = os.open('/var/log/nm.daemon', os.O_RDWR | os.O_APPEND | os.O_CREAT, 0644)
+    os.dup2(crashlog, 1)
+    os.dup2(crashlog, 2)
 
 def fork_as(su, function, *args):
     """fork(), cd / to avoid keeping unused directories open, close all nonstandard file descriptors (to avoid capturing open sockets), fork() again (to avoid zombies) and call <function> with arguments <args> in the grandchild process.  If <su> is not None, set our group and user ids appropriately in the child process."""
@@ -50,9 +49,10 @@ def fork_as(su, function, *args):
         try:
             os.chdir('/')
             close_nonstandard_fds()
-            pw_ent = pwd.getpwnam(su)
-            os.setegid(pw_ent[3])
-            os.seteuid(pw_ent[2])
+            if su:
+                pw_ent = pwd.getpwnam(su)
+                os.setegid(pw_ent[3])
+                os.seteuid(pw_ent[2])
             child_pid = os.fork()
             if child_pid == 0: function(*args)
         except:
@@ -62,7 +62,6 @@ def fork_as(su, function, *args):
         os._exit(0)
     else: os.waitpid(child_pid, 0)
 
-
 def pid_file():
     """We use a pid file to ensure that only one copy of NM is running at a given time.  If successful, this function will write a pid file containing the pid of the current process.  The return value is the pid of the other running process, or None otherwise."""
     other_pid = None
@@ -77,18 +76,67 @@ def pid_file():
             else: raise  # who knows
     if other_pid == None:
         # write a new pid file
-        write_file(PID_FILE, lambda thefile: thefile.write(str(os.getpid())))
+        write_file(PID_FILE, lambda f: f.write(str(os.getpid())))
     return other_pid
 
-
-def write_file(filename, do_write):
+def write_file(filename, do_write, **kw_args):
     """Write file <filename> atomically by opening a temporary file, using <do_write> to write that file, and then renaming the temporary file."""
-    os.rename(write_temp_file(do_write), filename)
-
+    os.rename(write_temp_file(do_write, **kw_args), filename)
 
-def write_temp_file(do_write):
+def write_temp_file(do_write, mode=None, uidgid=None):
     fd, temporary_filename = tempfile.mkstemp()
-    thefile = os.fdopen(fd, 'w')
-    do_write(thefile)
-    thefile.close()
+    if mode: os.chmod(temporary_filename, mode)
+    if uidgid: os.chown(temporary_filename, *uidgid)
+    f = os.fdopen(fd, 'w')
+    try: do_write(f)
+    finally: f.close()
     return temporary_filename
+
+# utilities functions to get (cached) information from the node
+
+# get node_id from /etc/planetlab/node_id and cache it
+_node_id=None
+def node_id():
+    global _node_id
+    if _node_id is None:
+        try:
+            _node_id=int(file("/etc/planetlab/node_id").read())
+        except:
+            _node_id=""
+    return _node_id
+
+# get slicefamily from /etc/planetlab/slicefamily and cache it
+# http://svn.planet-lab.org/wiki/SliceFamily
+_slicefamily=None
+def slicefamily():
+    global _slicefamily
+    if _slicefamily is None:
+        try:
+            _slicefamily=file("/etc/planetlab/slicefamily").read().strip()
+        except:
+            _slicefamily=""
+    return _slicefamily
+
+_root_context_arch=None
+def root_context_arch():
+    global _root_context_arch
+    if not _root_context_arch:
+        _root_context_arch=commands.getoutput("uname -i")
+    return _root_context_arch
+
+
+class NMLock:
+    def __init__(self, file):
+        logger.log("Lock %s initialized." % file, 2)
+        self.fd = os.open(file, os.O_RDWR|os.O_CREAT, 0600)
+        flags = fcntl.fcntl(self.fd, fcntl.F_GETFD)
+        flags |= fcntl.FD_CLOEXEC
+        fcntl.fcntl(self.fd, fcntl.F_SETFD, flags)
+    def __del__(self):
+        os.close(self.fd)
+    def acquire(self):
+        logger.log("Lock acquired.", 2)
+        fcntl.lockf(self.fd, fcntl.LOCK_SH)
+    def release(self):
+        logger.log("Lock released.", 2)
+        fcntl.lockf(self.fd, fcntl.LOCK_UN)