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-rw-r--r--src/server/PreProcessor.cpp46
1 files changed, 21 insertions, 25 deletions
diff --git a/src/server/PreProcessor.cpp b/src/server/PreProcessor.cpp
index 08d7bb4d..34ae48e7 100644
--- a/src/server/PreProcessor.cpp
+++ b/src/server/PreProcessor.cpp
@@ -33,8 +33,7 @@ PreProcessor::PreProcessor()
}
PreProcessor::~PreProcessor()
-{
-}
+{}
void
PreProcessor::event(Event* const ev)
@@ -47,14 +46,12 @@ PreProcessor::event(Event* const ev)
assert(!ev->next());
Event* const head = _head.get();
- Event* const tail = _tail.get();
-
if (!head) {
_head = ev;
_tail = ev;
} else {
+ _tail.get()->next(ev);
_tail = ev;
- tail->next(ev);
}
if (!_prepared_back.get()) {
@@ -72,18 +69,14 @@ PreProcessor::process(ProcessContext& context, PostProcessor& dest, bool limit)
return 0;
}
- /* Limit the maximum number of queued events to process per cycle. This
- makes the process callback (more) realtime-safe by preventing being
- choked by events coming in faster than they can be processed.
- FIXME: test this and figure out a good value
- */
- const size_t MAX_QUEUED_EVENTS = context.nframes() / 32;
-
- size_t num_events_processed = 0;
-
- Event* ev = head;
- Event* last = ev;
+ /* Limit the maximum number of events to process each cycle to ensure the
+ process callback is real-time safe. TODO: Parameterize this and/or
+ figure out a good default value. */
+ const size_t MAX_EVENTS_PER_CYCLE = context.nframes() / 4;
+ size_t n_processed = 0;
+ Event* ev = head;
+ Event* last = ev;
while (ev && ev->is_prepared() && ev->time() < context.end()) {
if (ev->time() < context.start()) {
// Didn't get around to executing in time, oh well...
@@ -91,26 +84,29 @@ PreProcessor::process(ProcessContext& context, PostProcessor& dest, bool limit)
}
ev->execute(context);
last = ev;
- ev = (Event*)ev->next();
- ++num_events_processed;
- if (limit && (num_events_processed > MAX_QUEUED_EVENTS))
+ ev = ev->next();
+ ++n_processed;
+ if (limit && (n_processed > MAX_EVENTS_PER_CYCLE)) {
break;
+ }
}
- if (num_events_processed > 0) {
+ if (n_processed > 0) {
Event* next = (Event*)last->next();
last->next(NULL);
dest.append(context, head, last);
+
+ // Since _head was not NULL, we know it hasn't been changed since
_head = next;
- if (!next) {
- _tail = NULL;
- }
+
+ /* If next is NULL, then _tail may now be invalid. However, in this
+ case _head is also NULL so event() will not read _tail. Since it
+ could cause a race with event(), _tail is not set to NULL here. */
}
- return num_events_processed;
+ return n_processed;
}
-/** Pre-process a single event */
void
PreProcessor::_run()
{