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Beware exceptions when processing input

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Added comment on the dangers of exceptions being raised when processing
input in the frontend.  Shuffled the exception handling around in the
vim controller.
This commit is contained in:
Bjorn Winckler
2009-04-10 18:33:02 +02:00
parent ac96dc67ba
commit 294d03baf6
2 changed files with 57 additions and 51 deletions
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src/MacVim/MMAppController.m
+6 -2
View File
@@ -2140,6 +2140,10 @@ fsEventCallback(ConstFSEventStreamRef streamRef,
return;
}
// NOTE: Be _very_ careful that no exceptions can be raised between here
// and the point at which 'processingFlag' is reset. Otherwise the above
// test could end up always failing and no input queues would ever be
// processed!
processingFlag = 1;
// NOTE: New input may arrive while we're busy processing; we deal with
@@ -2158,7 +2162,7 @@ fsEventCallback(ConstFSEventStreamRef streamRef,
for (i = 0; i < count; ++i) {
MMVimController *vc = [vimControllers objectAtIndex:i];
if (ukey == [vc identifier]) {
[vc processInputQueue:[queues objectForKey:key]];
[vc processInputQueue:[queues objectForKey:key]]; // !exceptions
break;
}
}
@@ -2169,7 +2173,7 @@ fsEventCallback(ConstFSEventStreamRef streamRef,
for (i = 0; i < count; ++i) {
MMVimController *vc = [cachedVimControllers objectAtIndex:i];
if (ukey == [vc identifier]) {
[vc processInputQueue:[queues objectForKey:key]];
[vc processInputQueue:[queues objectForKey:key]]; // !exceptions
break;
}
}
src/MacVim/MMVimController.m
+51 -49
View File
@@ -436,8 +436,15 @@ static BOOL isUnsafeMessage(int msgid);
{
if (!isInitialized) return;
[self doProcessInputQueue:queue];
[windowController processInputQueueDidFinish];
// NOTE: This method must not raise any exceptions (see comment in the
// calling method).
@try {
[self doProcessInputQueue:queue];
[windowController processInputQueueDidFinish];
}
@catch (NSException *ex) {
NSLog(@"[%s] Caught exception (pid=%d): %@", _cmd, pid, ex);
}
}
- (NSToolbarItem *)toolbar:(NSToolbar *)theToolbar
@@ -472,55 +479,50 @@ static BOOL isUnsafeMessage(int msgid);
{
NSMutableArray *delayQueue = nil;
@try {
unsigned i, count = [queue count];
if (count % 2) {
NSLog(@"WARNING: Uneven number of components (%d) in command "
"queue. Skipping...", count);
return;
}
//NSLog(@"======== %s BEGIN ========", _cmd);
for (i = 0; i < count; i += 2) {
NSData *value = [queue objectAtIndex:i];
NSData *data = [queue objectAtIndex:i+1];
int msgid = *((int*)[value bytes]);
//NSLog(@"%s%s", _cmd, MessageStrings[msgid]);
BOOL inDefaultMode = [[[NSRunLoop currentRunLoop] currentMode]
isEqual:NSDefaultRunLoopMode];
if (!inDefaultMode && isUnsafeMessage(msgid)) {
// NOTE: Because we may be listening to DO messages in "event
// tracking mode" we have to take extra care when doing things
// like releasing view items (and other Cocoa objects).
// Messages that may be potentially "unsafe" are delayed until
// the run loop is back to default mode at which time they are
// safe to call again.
// A problem with this approach is that it is hard to
// classify which messages are unsafe. As a rule of thumb, if
// a message may release an object used by the Cocoa framework
// (e.g. views) then the message should be considered unsafe.
// Delaying messages may have undesired side-effects since it
// means that messages may not be processed in the order Vim
// sent them, so beware.
if (!delayQueue)
delayQueue = [NSMutableArray array];
//NSLog(@"Adding unsafe message '%s' to delay queue (mode=%@)",
// MessageStrings[msgid],
// [[NSRunLoop currentRunLoop] currentMode]);
[delayQueue addObject:value];
[delayQueue addObject:data];
} else {
[self handleMessage:msgid data:data];
}
}
//NSLog(@"======== %s END ========", _cmd);
unsigned i, count = [queue count];
if (count % 2) {
NSLog(@"WARNING: Uneven number of components (%d) in command "
"queue. Skipping...", count);
return;
}
@catch (NSException *e) {
NSLog(@"Exception caught whilst processing command queue: %@", e);
//NSLog(@"======== %s BEGIN ========", _cmd);
for (i = 0; i < count; i += 2) {
NSData *value = [queue objectAtIndex:i];
NSData *data = [queue objectAtIndex:i+1];
int msgid = *((int*)[value bytes]);
//NSLog(@"%s%s", _cmd, MessageStrings[msgid]);
BOOL inDefaultMode = [[[NSRunLoop currentRunLoop] currentMode]
isEqual:NSDefaultRunLoopMode];
if (!inDefaultMode && isUnsafeMessage(msgid)) {
// NOTE: Because we may be listening to DO messages in "event
// tracking mode" we have to take extra care when doing things
// like releasing view items (and other Cocoa objects).
// Messages that may be potentially "unsafe" are delayed until
// the run loop is back to default mode at which time they are
// safe to call again.
// A problem with this approach is that it is hard to
// classify which messages are unsafe. As a rule of thumb, if
// a message may release an object used by the Cocoa framework
// (e.g. views) then the message should be considered unsafe.
// Delaying messages may have undesired side-effects since it
// means that messages may not be processed in the order Vim
// sent them, so beware.
if (!delayQueue)
delayQueue = [NSMutableArray array];
//NSLog(@"Adding unsafe message '%s' to delay queue (mode=%@)",
// MessageStrings[msgid],
// [[NSRunLoop currentRunLoop] currentMode]);
[delayQueue addObject:value];
[delayQueue addObject:data];
} else {
[self handleMessage:msgid data:data];
}
}
//NSLog(@"======== %s END ========", _cmd);
if (delayQueue) {
//NSLog(@" Flushing delay queue (%d items)", [delayQueue count]/2);