From 4685c63fab0eec5751979bcd99addcbdcaea5c60 Mon Sep 17 00:00:00 2001
From: Isaac Connor <isaac@zoneminder.com>
Date: Fri, 7 May 2021 14:04:51 -0400
Subject: [PATCH] Add early return if pktQueue is empty so we can assume that
 it isn't below.  Add notifications if we wake up and find that we have
 terminated so as to wake up any other waiters. Fixes failure to terminate
 when deinterlacing because both decoder and analysis are waiting

---
 src/zm_packetqueue.cpp | 25 ++++++++++++++++++++-----
 1 file changed, 20 insertions(+), 5 deletions(-)

diff --git a/src/zm_packetqueue.cpp b/src/zm_packetqueue.cpp
index 34f9f0f42..a1f149bb4 100644
--- a/src/zm_packetqueue.cpp
+++ b/src/zm_packetqueue.cpp
@@ -193,10 +193,11 @@ void PacketQueue::clearPackets(ZMPacket *add_packet) {
     return;
   }
   std::unique_lock<std::mutex> lck(mutex);
+  if (!pktQueue.size()) return;
 
   // If analysis_it isn't at the end, we need to keep that many additional packets
   int tail_count = 0;
-  if (pktQueue.size() and (pktQueue.back() != add_packet)) {
+  if (pktQueue.back() != add_packet) {
     packetqueue_iterator it = pktQueue.end();
     --it;
     while (*it != add_packet) {
@@ -205,7 +206,7 @@ void PacketQueue::clearPackets(ZMPacket *add_packet) {
       --it;
     }
   }
-  Debug(1, "Tail count is %d", tail_count);
+  Debug(1, "Tail count is %d, queue size is %lu", tail_count, pktQueue.size());
 
   if (!keep_keyframes) {
     // If not doing passthrough, we don't care about starting with a keyframe so logic is simpler
@@ -241,11 +242,17 @@ void PacketQueue::clearPackets(ZMPacket *add_packet) {
 
   // First packet is special because we know it is a video keyframe and only need to check for lock
   ZMPacket *zm_packet = *it;
+  Debug(1, "trying lock on first packet");
   ZMLockedPacket *lp = new ZMLockedPacket(zm_packet);
   if (lp->trylock()) {
+    Debug(1, "Have lock on first packet");
     ++it;
     delete lp;
 
+    if (it == pktQueue.end()) {
+      Debug(1, "Hit end already");
+      it = pktQueue.begin();
+    } else {
     // Since we have many packets in the queue, we should NOT be pointing at end so don't need to test for that
     while (*it != add_packet) {
       zm_packet = *it;
@@ -275,6 +282,7 @@ void PacketQueue::clearPackets(ZMPacket *add_packet) {
       }
       it++;
     } // end while
+    }
   }  // end if first packet not locked
   Debug(1, "Resulting pointing at latest packet? %d, next front points to begin? %d",
       ( *it == add_packet ),
@@ -419,7 +427,7 @@ unsigned int PacketQueue::clear(unsigned int frames_to_keep, int stream_id) {
 void PacketQueue::clear() {
   deleting = true;
   condition.notify_all();
-
+  Debug(1, "Clearing packetqueue");
   std::unique_lock<std::mutex> lck(mutex);
 
   while (!pktQueue.empty()) {
@@ -560,13 +568,19 @@ ZMLockedPacket *PacketQueue::get_packet(packetqueue_iterator *it) {
   ZMLockedPacket *lp = nullptr;
   while (!lp) {
     while (*it == pktQueue.end()) {
-      if (deleting or zm_terminate)
+      if (deleting or zm_terminate) {
+        Debug(1, "terminated, leaving");
+        condition.notify_all();
         return nullptr;
+      }
       Debug(2, "waiting.  Queue size %zu it == end? %d", pktQueue.size(), (*it == pktQueue.end()));
       condition.wait(lck);
     }
-    if (deleting or zm_terminate)
+    if (deleting or zm_terminate) {
+      Debug(1, "terminated, leaving");
+      condition.notify_all();
       return nullptr;
+    }
 
     ZMPacket *p = *(*it);
     if (!p) {
@@ -586,6 +600,7 @@ ZMLockedPacket *PacketQueue::get_packet(packetqueue_iterator *it) {
     }
     delete lp;
     lp = nullptr;
+    Debug(2, "waiting.  Queue size %zu it == end? %d", pktQueue.size(), (*it == pktQueue.end()));
     condition.wait(lck);
   }  // end while !lp
   return nullptr;