threading: minor improvements

Factorize string, enhance comments and minor code improvements.

Signed-off-by: Nicolas Sebrecht <nicolas.s-dev@laposte.net>

offlineimap/accounts.py

@@ -351,11 +351,12 @@ class SyncableAccount(Account):
                                  "[%s]"% (localfolder, localfolder.repository))
                     continue # Ignore filtered folder
                 if not globals.options.singlethreading:
-                    thread = InstanceLimitedThread(\
+                    thread = InstanceLimitedThread(
                         instancename = 'FOLDER_' + self.remoterepos.getname(),
                         target = syncfolder,
                         name = "Folder %s [acc: %s]"% (remotefolder.getexplainedname(), self),
-                        args = (self, remotefolder, quick))
+                        args = (self, remotefolder, quick)
+                        )
                     thread.start()
                     folderthreads.append(thread)
                 else:

offlineimap/folder/Base.py

@@ -871,11 +871,12 @@ class BaseFolder(object):
             # exceptions are caught in copymessageto()
             if self.suggeststhreads() and not globals.options.singlethreading:
                 self.waitforthread()
-                thread = threadutil.InstanceLimitedThread(\
+                thread = threadutil.InstanceLimitedThread(
                     self.getcopyinstancelimit(),
                     target = self.copymessageto,
                     name = "Copy message from %s:%s" % (self.repository, self),
-                    args = (uid, dstfolder, statusfolder))
+                    args = (uid, dstfolder, statusfolder)
+                    )
                 thread.start()
                 threads.append(thread)
             else:

offlineimap/init.py

@@ -35,6 +35,7 @@ from offlineimap.repository import Repository
 import traceback
 import collections
 
+ACCOUNT_LIMITED_THREAD_NAME = 'MAX_ACCOUNTS'
 
 def syncitall(list_accounts, config):
     """The target when in multithreading mode for running accounts threads."""
@@ -44,7 +45,7 @@ def syncitall(list_accounts, config):
         # Start a new thread per account and store it in the collection.
         account = accounts.SyncableAccount(config, accountname)
         thread = threadutil.InstanceLimitedThread(
-            instancename = 'ACCOUNTLIMIT',
+            instancename = ACCOUNT_LIMITED_THREAD_NAME,
             target = account.syncrunner,
             name = "Account sync %s"% accountname
             )
@@ -287,18 +288,27 @@ class OfflineImap:
         if socktimeout > 0:
             socket.setdefaulttimeout(socktimeout)
 
-        threadutil.initInstanceLimit('ACCOUNTLIMIT',
-            config.getdefaultint('general', 'maxsyncaccounts', 1))
+        threadutil.initInstanceLimit(
+            ACCOUNT_LIMITED_THREAD_NAME,
+            config.getdefaultint('general', 'maxsyncaccounts', 1)
+            )
 
         for reposname in config.getsectionlist('Repository'):
+            # XXX: We are likely lying around. If we must use at most n
+            # connections for a remote IMAP server, why do we allow twice this
+            # number? The max connections number is used by both the FOLDER_ and
+            # the MSGCOPY_ prefixes!
             for instancename in ["FOLDER_" + reposname,
                                  "MSGCOPY_" + reposname]:
                 if options.singlethreading:
                     threadutil.initInstanceLimit(instancename, 1)
                 else:
-                    threadutil.initInstanceLimit(instancename,
-                        config.getdefaultint('Repository ' + reposname,
-                                                  'maxconnections', 2))
+                    threadutil.initInstanceLimit(
+                        instancename,
+                        config.getdefaultint(
+                            'Repository ' + reposname,
+                            'maxconnections', 2)
+                        )
         self.config = config
         return (options, args)
 

offlineimap/threadutil.py

@@ -224,8 +224,10 @@ class ExitNotifyThread(Thread):
 instancelimitedsems = {}
 
 def initInstanceLimit(instancename, instancemax):
-    """Initialize the instance-limited thread implementation to permit
-    up to intancemax threads with the given instancename."""
+    """Initialize the instance-limited thread implementation.
+
+    Run up to intancemax threads for the given instancename. This allows
+    to honor maxsyncaccounts and maxconnections."""
 
     global instancelimitedsems
 
@@ -235,6 +237,7 @@ def initInstanceLimit(instancename, instancemax):
 
 class InstanceLimitedThread(ExitNotifyThread):
     def __init__(self, instancename, *args, **kwargs):
+        # XXX: this is not a instance name, is it?
         self.instancename = instancename
         super(InstanceLimitedThread, self).__init__(*args, **kwargs)