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Properly re-raise exception to save original tracebacks

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We usually mutate some exceptions to OfflineImapError() and it is
a whole lot better if such exception will show up with the original
traceback, so all valid occurrences of such mutations were transformed
to the 3-tuple form of "raise".  Had also added coding guidelines
document where this re-raise strategy is documented.

Signed-off-by: Eygene Ryabinkin <rea@codelabs.ru>
This commit is contained in:
Eygene Ryabinkin 2015-01-11 23:44:24 +03:00
parent 8c6abc413e
commit e7fabf9e57
15 changed files with 150 additions and 26 deletions
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102
docs/CodingGuidelines.rst Normal file
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@ -0,0 +1,102 @@
.. -*- coding: utf-8 -*-
.. _OfflineIMAP: https://github.com/OfflineIMAP/offlineimap
.. _OLI_git_repo: git://github.com/OfflineIMAP/offlineimap.git
=================================
Coding guidelines for OfflineIMAP
=================================
.. contents::
.. .. sectnum::
This document contains assorted guidelines for programmers that want
to hack OfflineIMAP.
------------------
Exception handling
------------------
OfflineIMAP on many occasions re-raises various exceptions and often
changes exception type to `OfflineImapError`. This is not a problem
per se, but you must always remember that we need to preserve original
tracebacks. This is not hard if you follow these simple rules.
For re-raising original exceptions, just use::
raise
from inside your exception handling code.
If you need to change exception type, or its argument, or whatever,
use this three-argument form::
raise YourExceptionClass(argum, ents), None, sys.exc_info()[2]
In this form, you're creating an instance of new exception, so ``raise``
will deduce its ``type`` and ``value`` parameters from the first argument,
thus the second expression passed to ``raise`` is always ``None``.
And the third one is the traceback object obtained from the thread-safe
``exc_info()`` function.
In fact, if you hadn't already imported the whole ``sys`` module, it will
be better to import just ``exc_info()``::
from sys import exc_info
and raise like this::
raise YourExceptionClass(argum, ents), None, exc_info()[2]
since this is the historically-preferred style in the OfflineIMAP code.
.. -*- coding: utf-8 -*-
.. _OfflineIMAP: https://github.com/OfflineIMAP/offlineimap
.. _OLI_git_repo: git://github.com/OfflineIMAP/offlineimap.git
=================================
Coding guidelines for OfflineIMAP
=================================
.. contents::
.. .. sectnum::
This document contains assorted guidelines for programmers that want
to hack OfflineIMAP.
------------------
Exception handling
------------------
OfflineIMAP on many occasions re-raises various exceptions and often
changes exception type to `OfflineImapError`. This is not a problem
per se, but you must always remember that we need to preserve original
tracebacks. This is not hard if you follow these simple rules.
For re-raising original exceptions, just use::
raise
from inside your exception handling code.
If you need to change exception type, or its argument, or whatever,
use this three-argument form::
raise YourExceptionClass(argum, ents), None, sys.exc_info()[2]
In this form, you're creating an instance of new exception, so ``raise``
will deduce its ``type`` and ``value`` parameters from the first argument,
thus the second expression passed to ``raise`` is always ``None``.
And the third one is the traceback object obtained from the thread-safe
``exc_info()`` function.
In fact, if you hadn't already imported the whole ``sys`` module, it will
be better to import just ``exc_info()``::
from sys import exc_info
and raise like this::
raise YourExceptionClass(argum, ents), None, exc_info()[2]
since this is the historically-preferred style in the OfflineIMAP code.

1
docs/doc-src/CodingGuidelines.rst Symbolic link
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@ -0,0 +1 @@
../CodingGuidelines.rst

3
offlineimap/CustomConfig.py
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@ -16,6 +16,7 @@
import os
import re
from sys import exc_info
try:
from ConfigParser import SafeConfigParser, Error
@ -75,7 +76,7 @@ class CustomConfigParser(SafeConfigParser):
return re.split(separator_re, val)
except re.error as e:
raise Error("Bad split regexp '%s': %s" % \
(separator_re, e))
(separator_re, e)), None, exc_info()[2]
def getdefaultlist(self, section, option, default, separator_re):
"""Same as getlist, but returns the value of `default`

3
offlineimap/accounts.py
View File

@ -210,7 +210,8 @@ class SyncableAccount(Account):
self._lockfd.close()
raise OfflineImapError("Could not lock account %s. Is another "
"instance using this account?" % self,
OfflineImapError.ERROR.REPO)
OfflineImapError.ERROR.REPO), \
None, exc_info()[2]
def _unlock(self):
"""Unlock the account, deleting the lock file"""

4
offlineimap/folder/Gmail.py
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@ -17,6 +17,7 @@
# Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
import re
from sys import exc_info
from offlineimap import imaputil, OfflineImapError
from offlineimap import imaplibutil
@ -144,7 +145,8 @@ class GmailFolder(IMAPFolder):
raise OfflineImapError("FETCHING UIDs in folder [%s]%s failed. " % \
(self.getrepository(), self) + \
"Server responded '[%s] %s'" % \
(res_type, response), OfflineImapError.ERROR.FOLDER)
(res_type, response), OfflineImapError.ERROR.FOLDER), \
None, exc_info()[2]
finally:
self.imapserver.releaseconnection(imapobj)

4
offlineimap/folder/GmailMaildir.py
View File

@ -17,6 +17,7 @@
import os
from sys import exc_info
from .Maildir import MaildirFolder
from offlineimap import OfflineImapError
import offlineimap.accounts
@ -170,7 +171,8 @@ class GmailMaildirFolder(MaildirFolder):
os.rename(tmppath, filepath)
except OSError as e:
raise OfflineImapError("Can't rename file '%s' to '%s': %s" % \
(tmppath, filepath, e[1]), OfflineImapError.ERROR.FOLDER)
(tmppath, filepath, e[1]), OfflineImapError.ERROR.FOLDER), \
None, exc_info()[2]
if rtime != None:
os.utime(filepath, (rtime, rtime))

9
offlineimap/folder/IMAP.py
View File

@ -594,7 +594,9 @@ class IMAPFolder(BaseFolder):
"repository '%s' failed (abort). Server responded: %s\n"
"Message content was: %s"%
(msg_id, self, self.getrepository(), str(e), dbg_output),
OfflineImapError.ERROR.MESSAGE)
OfflineImapError.ERROR.MESSAGE), \
None, exc_info()[2]
# XXX: is this still needed?
self.ui.error(e, exc_info()[2])
except imapobj.error as e: # APPEND failed
# If the server responds with 'BAD', append()
@ -604,8 +606,8 @@ class IMAPFolder(BaseFolder):
imapobj = None
raise OfflineImapError("Saving msg (%s) folder '%s', repo '%s'"
"failed (error). Server responded: %s\nMessage content was: "
"%s"% (msg_id, self, self.getrepository(), str(e), dbg_output),
OfflineImapError.ERROR.MESSAGE)
"%s" % (msg_id, self, self.getrepository(), str(e), dbg_output),
OfflineImapError.ERROR.MESSAGE), None, exc_info()[2]
# Checkpoint. Let it write out stuff, etc. Eg searches for
# just uploaded messages won't work if we don't do this.
(typ,dat) = imapobj.check()
@ -676,6 +678,7 @@ class IMAPFolder(BaseFolder):
imapobj = self.imapserver.acquireconnection()
self.ui.error(e, exc_info()[2])
fails_left -= 1
# self.ui.error() will show the original traceback
if not fails_left:
raise e
if data == [None] or res_type != 'OK':

5
offlineimap/folder/LocalStatus.py
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@ -15,6 +15,7 @@
# along with this program; if not, write to the Free Software
# Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
from sys import exc_info
import os
import threading
@ -79,7 +80,7 @@ class LocalStatusFolder(BaseFolder):
errstr = "Corrupt line '%s' in cache file '%s'" % \
(line, self.filename)
self.ui.warn(errstr)
raise ValueError(errstr)
raise ValueError(errstr), None, exc_info()[2]
self.messagelist[uid] = self.msglist_item_initializer(uid)
self.messagelist[uid]['flags'] = flags
@ -103,7 +104,7 @@ class LocalStatusFolder(BaseFolder):
errstr = "Corrupt line '%s' in cache file '%s'" % \
(line, self.filename)
self.ui.warn(errstr)
raise ValueError(errstr)
raise ValueError(errstr), None, exc_info()[2]
self.messagelist[uid] = self.msglist_item_initializer(uid)
self.messagelist[uid]['flags'] = flags
self.messagelist[uid]['mtime'] = mtime

3
offlineimap/folder/LocalStatusSQLite.py
View File

@ -16,6 +16,7 @@
# Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
import os
import re
from sys import exc_info
from threading import Lock
from .Base import BaseFolder
try:
@ -66,7 +67,7 @@ class LocalStatusSQLiteFolder(BaseFolder):
except NameError:
# sqlite import had failed
raise UserWarning('SQLite backend chosen, but no sqlite python '
'bindings available. Please install.')
'bindings available. Please install.'), None, exc_info()[2]
#Make sure sqlite is in multithreading SERIALIZE mode
assert sqlite.threadsafety == 1, 'Your sqlite is not multithreading safe.'

6
offlineimap/folder/Maildir.py
View File

@ -19,6 +19,7 @@ import socket
import time
import re
import os
from sys import exc_info
from .Base import BaseFolder
from threading import Lock
try:
@ -282,7 +283,7 @@ class MaildirFolder(BaseFolder):
continue
severity = OfflineImapError.ERROR.MESSAGE
raise OfflineImapError("Unique filename %s already exists." % \
filename, severity)
filename, severity), None, exc_info()[2]
else:
raise
@ -372,7 +373,8 @@ class MaildirFolder(BaseFolder):
except OSError as e:
raise OfflineImapError("Can't rename file '%s' to '%s': %s" % (
oldfilename, newfilename, e[1]),
OfflineImapError.ERROR.FOLDER)
OfflineImapError.ERROR.FOLDER), \
None, exc_info()[2]
self.messagelist[uid]['flags'] = flags
self.messagelist[uid]['filename'] = newfilename

6
offlineimap/folder/UIDMaps.py
View File

@ -14,6 +14,8 @@
# You should have received a copy of the GNU General Public License
# along with this program; if not, write to the Free Software
# Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
from sys import exc_info
from threading import Lock
from offlineimap import OfflineImapError
from .IMAP import IMAPFolder
@ -60,7 +62,7 @@ class MappedIMAPFolder(IMAPFolder):
line = line.strip()
except ValueError:
raise Exception("Corrupt line '%s' in UID mapping file '%s'"%
(line, mapfilename))
(line, mapfilename)), None, exc_info()[2]
(str1, str2) = line.split(':')
loc = long(str1)
rem = long(str2)
@ -89,7 +91,7 @@ class MappedIMAPFolder(IMAPFolder):
raise OfflineImapError("Could not find UID for msg '{0}' (f:'{1}'."
" This is usually a bad thing and should be reported on the ma"
"iling list.".format(e.args[0], self),
OfflineImapError.ERROR.MESSAGE)
OfflineImapError.ERROR.MESSAGE), None, exc_info()[2]
# Interface from BaseFolder
def cachemessagelist(self):

3
offlineimap/imaplibutil.py
View File

@ -18,6 +18,7 @@ import os
import fcntl
import time
import subprocess
from sys import exc_info
import threading
from hashlib import sha1
@ -54,7 +55,7 @@ class UsefulIMAPMixIn(object):
errstr = "Server '%s' closed connection, error on SELECT '%s'. Ser"\
"ver said: %s" % (self.host, mailbox, e.args[0])
severity = OfflineImapError.ERROR.FOLDER_RETRY
raise OfflineImapError(errstr, severity)
raise OfflineImapError(errstr, severity), None, exc_info()[2]
if result[0] != 'OK':
#in case of error, bail out with OfflineImapError
errstr = "Error SELECTing mailbox '%s', server reply:\n%s" %\

16
offlineimap/imapserver.py
View File

@ -206,8 +206,8 @@ class IMAPServer:
imapobj.starttls()
except imapobj.error as e:
raise OfflineImapError("Failed to start "
"TLS connection: %s"% str(e),
OfflineImapError.ERROR.REPO)
"TLS connection: %s" % str(e),
OfflineImapError.ERROR.REPO, None, exc_info()[2])
## All __authn_* procedures are helpers that do authentication.
@ -466,7 +466,7 @@ class IMAPServer:
"'%s'. Make sure you have configured the ser"\
"ver name correctly and that you are online."%\
(self.hostname, self.repos)
raise OfflineImapError(reason, severity)
raise OfflineImapError(reason, severity), None, exc_info()[2]
elif isinstance(e, SSLError) and e.errno == 1:
# SSL unknown protocol error
@ -479,7 +479,7 @@ class IMAPServer:
reason = "Unknown SSL protocol connecting to host '%s' for "\
"repository '%s'. OpenSSL responded:\n%s"\
% (self.hostname, self.repos, e)
raise OfflineImapError(reason, severity)
raise OfflineImapError(reason, severity), None, exc_info()[2]
elif isinstance(e, socket.error) and e.args[0] == errno.ECONNREFUSED:
# "Connection refused", can be a non-existing port, or an unauthorized
@ -487,15 +487,15 @@ class IMAPServer:
reason = "Connection to host '%s:%d' for repository '%s' was "\
"refused. Make sure you have the right host and port "\
"configured and that you are actually able to access the "\
"network."% (self.hostname, self.port, self.repos)
raise OfflineImapError(reason, severity)
"network." % (self.hostname, self.port, self.repos)
raise OfflineImapError(reason, severity), None, exc_info()[2]
# Could not acquire connection to the remote;
# socket.error(last_error) raised
if str(e)[:24] == "can't open socket; error":
raise OfflineImapError("Could not connect to remote server '%s' "\
"for repository '%s'. Remote does not answer."
% (self.hostname, self.repos),
OfflineImapError.ERROR.REPO)
OfflineImapError.ERROR.REPO), None, exc_info()[2]
else:
# re-raise all other errors
raise
@ -702,7 +702,7 @@ class IdleThread(object):
self.ui.error(e, exc_info()[2])
self.parent.releaseconnection(imapobj, True)
else:
raise e
raise
else:
success = True
if "IDLE" in imapobj.capabilities:

3
offlineimap/repository/IMAP.py
View File

@ -103,7 +103,8 @@ class IMAPRepository(BaseRepository):
except Exception as e:
raise OfflineImapError("remotehosteval option for repository "\
"'%s' failed:\n%s" % (self, e),
OfflineImapError.ERROR.REPO)
OfflineImapError.ERROR.REPO), \
None, exc_info()[2]
if host:
self._host = host
return self._host

8
offlineimap/repository/__init__.py
View File

@ -15,6 +15,8 @@
# along with this program; if not, write to the Free Software
# Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
from sys import exc_info
try:
from configparser import NoSectionError
except ImportError: #python2
@ -66,14 +68,16 @@ class Repository(object):
except NoSectionError as e:
errstr = ("Could not find section '%s' in configuration. Required "
"for account '%s'." % ('Repository %s' % name, account))
raise OfflineImapError(errstr, OfflineImapError.ERROR.REPO)
raise OfflineImapError(errstr, OfflineImapError.ERROR.REPO), \
None, exc_info()[2]
try:
repo = typemap[repostype]
except KeyError:
errstr = "'%s' repository not supported for '%s' repositories." \
% (repostype, reqtype)
raise OfflineImapError(errstr, OfflineImapError.ERROR.REPO)
raise OfflineImapError(errstr, OfflineImapError.ERROR.REPO), \
None, exc_info()[2]
return repo(name, account)