try to clean up locking issues with TempoMap

git-svn-id: svn://localhost/ardour2/branches/3.0@11161 d708f5d6-7413-0410-9779-e7cbd77b26cf

diff --git a/libs/ardour/ardour/tempo.h b/libs/ardour/ardour/tempo.h
index f0a63be05ffa22ed624ddf18c05e3b846e671dfa..09d8a646950cdab0305a03fdae8daecd604a114c 100644 (file)
--- a/libs/ardour/ardour/tempo.h
+++ b/libs/ardour/ardour/tempo.h
@@ -223,7 +223,7 @@ class TempoMap : public PBD::StatefulDestructible
        typedef std::vector<BBTPoint> BBTPointList;
 
        template<class T> void apply_with_metrics (T& obj, void (T::*method)(const Metrics&)) {
-               Glib::RWLock::ReaderLock lm (metrics_lock);
+               Glib::RWLock::ReaderLock lm (lock);
                (obj.*method)(*metrics);
        }
 
@@ -297,11 +297,10 @@ class TempoMap : public PBD::StatefulDestructible
        framepos_t           last_bbt_when;
        bool                 last_bbt_valid;
        Timecode::BBT_Time   last_bbt;
-       mutable Glib::RWLock metrics_lock;
-       mutable Glib::RWLock map_lock;
+       mutable Glib::RWLock lock;
        BBTPointList*       _map;
 
-       void recompute_map (bool reassign_tempo_bbt, framepos_t end = -1);
+       void recompute_map (bool reassign_tempo_bbt, bool use_write_lock, framepos_t end = -1);
         void require_map_to (framepos_t pos);
         void require_map_to (const Timecode::BBT_Time&);
 
@@ -309,11 +308,9 @@ class TempoMap : public PBD::StatefulDestructible
        BBTPointList::const_iterator bbt_after_or_at (framepos_t);
        BBTPointList::const_iterator bbt_point_for (const Timecode::BBT_Time&);
        
-       void timestamp_metrics_from_audio_time ();
-       
        framepos_t round_to_type (framepos_t fr, int dir, BBTPointType);
        
-        void bbt_time_unlocked (framepos_t, Timecode::BBT_Time&, const BBTPointList::const_iterator&);
+        void bbt_time (framepos_t, Timecode::BBT_Time&, const BBTPointList::const_iterator&);
        
        framecnt_t bbt_duration_at_unlocked (const Timecode::BBT_Time& when, const Timecode::BBT_Time& bbt, int dir);
        

diff --git a/libs/ardour/tempo.cc b/libs/ardour/tempo.cc
index 5d027462100a36a73467aa604a3efb68831f7304..23dd34c9622edb51d48088139116e655956c442a 100644 (file)
--- a/libs/ardour/tempo.cc
+++ b/libs/ardour/tempo.cc
@@ -311,7 +311,7 @@ TempoMap::remove_tempo (const TempoSection& tempo, bool complete_operation)
        bool removed = false;
 
        {
-               Glib::RWLock::WriterLock lm (metrics_lock);
+               Glib::RWLock::WriterLock lm (lock);
                Metrics::iterator i;
 
                for (i = metrics->begin(); i != metrics->end(); ++i) {
@@ -325,10 +325,13 @@ TempoMap::remove_tempo (const TempoSection& tempo, bool complete_operation)
                                }
                        }
                }
+
+               if (removed && complete_operation) {
+                       recompute_map (false, false);
+               }
        }
 
        if (removed && complete_operation) {
-               recompute_map (false);
                PropertyChanged (PropertyChange ());
        }
 }
@@ -339,7 +342,7 @@ TempoMap::remove_meter (const MeterSection& tempo, bool complete_operation)
        bool removed = false;
 
        {
-               Glib::RWLock::WriterLock lm (metrics_lock);
+               Glib::RWLock::WriterLock lm (lock);
                Metrics::iterator i;
 
                for (i = metrics->begin(); i != metrics->end(); ++i) {
@@ -353,10 +356,13 @@ TempoMap::remove_meter (const MeterSection& tempo, bool complete_operation)
                                }
                        }
                }
+
+               if (removed && complete_operation) {
+                       recompute_map (true, false);
+               }
        }
 
        if (removed && complete_operation) {
-               recompute_map (true);
                PropertyChanged (PropertyChange ());
        }
 }
@@ -471,12 +477,11 @@ TempoMap::replace_tempo (const TempoSection& ts, const Tempo& tempo, const BBT_T
                add_tempo (tempo, where);
        } else {
                {
-                       Glib::RWLock::WriterLock lm (metrics_lock);
+                       Glib::RWLock::WriterLock lm (lock);
                        /* cannot move the first tempo section */
                        *((Tempo*)&first) = tempo;
+                       recompute_map (false, false);
                }
-
-               recompute_map (false);
        }
 
        PropertyChanged (PropertyChange ());
@@ -486,7 +491,7 @@ void
 TempoMap::add_tempo (const Tempo& tempo, BBT_Time where)
 {
        {
-               Glib::RWLock::WriterLock lm (metrics_lock);
+               Glib::RWLock::WriterLock lm (lock);
 
                /* new tempos always start on a beat */
                where.ticks = 0;
@@ -524,9 +529,10 @@ TempoMap::add_tempo (const Tempo& tempo, BBT_Time where)
                /* and insert it */
                
                do_insert (ts);
+
+               recompute_map (false, false);
        }
 
-       recompute_map (false);
 
        PropertyChanged (PropertyChange ());
 }
@@ -541,11 +547,11 @@ TempoMap::replace_meter (const MeterSection& ms, const Meter& meter, const BBT_T
                add_meter (meter, where);
        } else {
                {
-                       Glib::RWLock::WriterLock lm (metrics_lock);
+                       Glib::RWLock::WriterLock lm (lock);
                        /* cannot move the first meter section */
                        *((Meter*)&first) = meter;
+                       recompute_map (true, false);
                }
-               recompute_map (true);
        }
 
        PropertyChanged (PropertyChange ());
@@ -555,7 +561,7 @@ void
 TempoMap::add_meter (const Meter& meter, BBT_Time where)
 {
        {
-               Glib::RWLock::WriterLock lm (metrics_lock);
+               Glib::RWLock::WriterLock lm (lock);
 
                /* a new meter always starts a new bar on the first beat. so
                   round the start time appropriately. remember that
@@ -573,9 +579,9 @@ TempoMap::add_meter (const Meter& meter, BBT_Time where)
                where.ticks = 0;
                
                do_insert (new MeterSection (where, meter.divisions_per_bar(), meter.note_divisor()));
+               recompute_map (true, false);
        }
 
-       recompute_map (true);
        
 #ifndef NDEBUG
        if (DEBUG_ENABLED(DEBUG::TempoMap)) {
@@ -595,10 +601,10 @@ TempoMap::change_initial_tempo (double beats_per_minute, double note_type)
        for (Metrics::iterator i = metrics->begin(); i != metrics->end(); ++i) {
                if ((t = dynamic_cast<TempoSection*> (*i)) != 0) {
                        {
-                               Glib::RWLock::WriterLock lm (metrics_lock);
+                               Glib::RWLock::WriterLock lm (lock);
                                *((Tempo*) t) = newtempo;
+                               recompute_map (false, false);
                        }
-                       recompute_map (false);
                        PropertyChanged (PropertyChange ());
                        break;
                }
@@ -645,12 +651,12 @@ TempoMap::change_existing_tempo_at (framepos_t where, double beats_per_minute, d
        /* reset */
 
        {
-               Glib::RWLock::WriterLock lm (metrics_lock);
+               Glib::RWLock::WriterLock lm (lock);
                /* cannot move the first tempo section */
                *((Tempo*)prev) = newtempo;
+               recompute_map (false, false);
        }
 
-       recompute_map (false);
        PropertyChanged (PropertyChange ());
 }
 
@@ -686,121 +692,31 @@ TempoMap::first_tempo () const
        return *t;
 }
 
-void
-TempoMap::timestamp_metrics_from_audio_time ()
-{
-       Metrics::iterator i;
-       const MeterSection* meter;
-       const TempoSection* tempo;
-       MeterSection *m;
-       TempoSection *t;
-
-       meter = &first_meter ();
-       tempo = &first_tempo ();
-
-       BBT_Time start;
-       BBT_Time end;
-       
-       // cerr << "\n###################### TIMESTAMP via AUDIO ##############\n" << endl;
-
-       bool first = true;
-       MetricSection* prev = 0;
-
-       for (i = metrics->begin(); i != metrics->end(); ++i) {
-
-               BBT_Time bbt;
-               TempoMetric metric (*meter, *tempo);
-
-               if (prev) {
-                       metric.set_start (prev->start());
-                       metric.set_frame (prev->frame());
-               } else {
-                       // metric will be at frames=0 bbt=1|1|0 by default
-                       // which is correct for our purpose
-               }
-
-               BBTPointList::const_iterator bi = bbt_before_or_at ((*i)->frame());
-               bbt_time_unlocked ((*i)->frame(), bbt, bi);
-               
-               // cerr << "timestamp @ " << (*i)->frame() << " with " << bbt.bars << "|" << bbt.beats << "|" << bbt.ticks << " => ";
-
-               if (first) {
-                       first = false;
-               } else {
-
-                       if (bbt.ticks > BBT_Time::ticks_per_bar_division/2) {
-                               /* round up to next beat */
-                               bbt.beats += 1;
-                       }
-
-                       bbt.ticks = 0;
-
-                       if (bbt.beats != 1) {
-                               /* round up to next bar */
-                               bbt.bars += 1;
-                               bbt.beats = 1;
-                       }
-               }
-
-               // cerr << bbt << endl;
-
-               (*i)->set_start (bbt);
-                       
-               if ((t = dynamic_cast<TempoSection*>(*i)) != 0) {
-                       tempo = t;
-                       // cerr << "NEW TEMPO, frame = " << (*i)->frame() << " start = " << (*i)->start() <<endl;
-               } else if ((m = dynamic_cast<MeterSection*>(*i)) != 0) {
-                       meter = m;
-                       // cerr << "NEW METER, frame = " << (*i)->frame() << " start = " << (*i)->start() <<endl;
-               } else {
-                       fatal << _("programming error: unhandled MetricSection type") << endmsg;
-                       /*NOTREACHED*/
-               }
-
-               prev = (*i);
-       }
-
-#ifndef NDEBUG
-       if (DEBUG_ENABLED(DEBUG::TempoMap)) {
-               dump (cerr);
-       }
-#endif
-
-}
-
 void
 TempoMap::require_map_to (framepos_t pos)
 {
-       bool revise_map;
+       /* CALLER MUST HOLD READ LOCK AND MAY NOT HOLD WRITE LOCK */
 
-       {
-               Glib::RWLock::ReaderLock lm (map_lock);
-               revise_map = (_map->empty() || _map->back().frame < pos);
-       }
-
-       if (revise_map) {
-               recompute_map (false, pos);
+       if (_map->empty() || _map->back().frame < pos) {
+               recompute_map (false, true, pos);
        }
 }
 
 void
 TempoMap::require_map_to (const BBT_Time& bbt)
 {
-       bool revise_map;
-
-       {
-               Glib::RWLock::ReaderLock lm (map_lock);
-               revise_map = (_map->empty() || _map->back().bbt() < bbt);
-       }
-
-       if (revise_map) {
-               recompute_map (false, 99);
+       /* CALLER MUST HOLD READ LOCK AND MAY NOT HOLD WRITE LOCK */
+       
+       if (_map->empty() || _map->back().bbt() < bbt) {
+               recompute_map (false, true, 99);
        }
 }
 
 void
-TempoMap::recompute_map (bool reassign_tempo_bbt, framepos_t end)
+TempoMap::recompute_map (bool reassign_tempo_bbt, bool use_write_lock, framepos_t end)
 {
+       /* CALLER MUST HOLD READ LOCK AND MAY HOLD WRITE LOCK */
+
        MeterSection* meter;
        TempoSection* tempo;
        TempoSection* ts;
@@ -814,8 +730,6 @@ TempoMap::recompute_map (bool reassign_tempo_bbt, framepos_t end)
 
        if (end < 0) {
 
-               Glib::RWLock::ReaderLock lm (map_lock);
-
                if (_map->empty()) {
                        /* compute 1 mins worth */
                        end = _frame_rate * 60;
@@ -826,8 +740,6 @@ TempoMap::recompute_map (bool reassign_tempo_bbt, framepos_t end)
 
        DEBUG_TRACE (DEBUG::TempoMath, string_compose ("recomputing tempo map, zero to %1\n", end));
 
-       Glib::RWLock::ReaderLock lm (metrics_lock);
-       
        for (Metrics::iterator i = metrics->begin(); i != metrics->end(); ++i) {
                if ((ms = dynamic_cast<MeterSection *> (*i)) != 0) {
                        meter = ms;
@@ -995,17 +907,20 @@ TempoMap::recompute_map (bool reassign_tempo_bbt, framepos_t end)
                }
        }
 
-       {
-               Glib::RWLock::WriterLock lm (map_lock);
+       if (use_write_lock) {
+               Glib::RWLock::WriterLock lm (lock);
+               swap (_map, new_map);
+       } else {
                swap (_map, new_map);
-               delete new_map;
        }
+
+       delete new_map;
 }
 
 TempoMetric
 TempoMap::metric_at (framepos_t frame) const
 {
-       Glib::RWLock::ReaderLock lm (metrics_lock);
+       Glib::RWLock::ReaderLock lm (lock);
        TempoMetric m (first_meter(), first_tempo());
        const Meter* meter;
        const Tempo* tempo;
@@ -1042,7 +957,7 @@ TempoMap::metric_at (framepos_t frame) const
 TempoMetric
 TempoMap::metric_at (BBT_Time bbt) const
 {
-       Glib::RWLock::ReaderLock lm (metrics_lock);
+       Glib::RWLock::ReaderLock lm (lock);
        TempoMetric m (first_meter(), first_tempo());
        const Meter* meter;
        const Tempo* tempo;
@@ -1078,16 +993,26 @@ TempoMap::metric_at (BBT_Time bbt) const
 void
 TempoMap::bbt_time (framepos_t frame, BBT_Time& bbt)
 {
-       {
-               Glib::RWLock::ReaderLock lm (map_lock);
-               BBTPointList::const_iterator i = bbt_before_or_at (frame);
-               bbt_time_unlocked (frame, bbt, i);
+       Glib::RWLock::ReaderLock lm (lock);
+
+       const BBTPointList::const_iterator& i = bbt_before_or_at (frame);
+
+       bbt.bars = (*i).bar;
+       bbt.beats = (*i).beat;
+
+       if ((*i).frame == frame) {
+               bbt.ticks = 0;
+       } else {
+               bbt.ticks = llrint (((frame - (*i).frame) / (*i).meter->frames_per_division(*((*i).tempo), _frame_rate)) *
+                                   BBT_Time::ticks_per_bar_division);
        }
 }
 
 void
-TempoMap::bbt_time_unlocked (framepos_t frame, BBT_Time& bbt, const BBTPointList::const_iterator& i)
+TempoMap::bbt_time (framepos_t frame, BBT_Time& bbt, const BBTPointList::const_iterator& i)
 {
+       /* CALLER MUST HOLD READ LOCK */
+
        bbt.bars = (*i).bar;
        bbt.beats = (*i).beat;
 
@@ -1102,7 +1027,7 @@ TempoMap::bbt_time_unlocked (framepos_t frame, BBT_Time& bbt, const BBTPointList
 framepos_t
 TempoMap::frame_time (const BBT_Time& bbt)
 {
-       Glib::RWLock::ReaderLock lm (map_lock);
+       Glib::RWLock::ReaderLock lm (lock);
 
        BBTPointList::const_iterator s = bbt_point_for (BBT_Time (1, 1, 0));
        BBTPointList::const_iterator e = bbt_point_for (BBT_Time (bbt.bars, bbt.beats, 0));
@@ -1118,7 +1043,7 @@ TempoMap::frame_time (const BBT_Time& bbt)
 framecnt_t
 TempoMap::bbt_duration_at (framepos_t pos, const BBT_Time& bbt, int dir)
 {
-       Glib::RWLock::ReaderLock lm (map_lock);
+       Glib::RWLock::ReaderLock lm (lock);
        framecnt_t frames = 0;
        BBT_Time when;
 
@@ -1189,13 +1114,13 @@ TempoMap::round_to_beat (framepos_t fr, int dir)
 framepos_t
 TempoMap::round_to_beat_subdivision (framepos_t fr, int sub_num, int dir)
 {
-       Glib::RWLock::ReaderLock lm (map_lock);
+       Glib::RWLock::ReaderLock lm (lock);
        BBTPointList::const_iterator i = bbt_before_or_at (fr);
        BBT_Time the_beat;
        uint32_t ticks_one_subdivisions_worth;
        uint32_t difference;
 
-       bbt_time_unlocked (fr, the_beat, i);
+       bbt_time (fr, the_beat, i);
 
        DEBUG_TRACE (DEBUG::SnapBBT, string_compose ("round %1 to nearest 1/%2 beat, before-or-at = %3 @ %4|%5 precise = %6\n",
                                                     fr, sub_num, (*i).frame, (*i).bar, (*i).beat, the_beat));
@@ -1306,7 +1231,7 @@ TempoMap::round_to_beat_subdivision (framepos_t fr, int sub_num, int dir)
 framepos_t
 TempoMap::round_to_type (framepos_t frame, int dir, BBTPointType type)
 {
-       Glib::RWLock::ReaderLock lm (map_lock);
+       Glib::RWLock::ReaderLock lm (lock);
        BBTPointList::const_iterator fi;
 
        if (dir > 0) {
@@ -1441,6 +1366,7 @@ TempoMap::map (TempoMap::BBTPointList::const_iterator& begin,
               TempoMap::BBTPointList::const_iterator& end, 
               framepos_t lower, framepos_t upper) 
 {
+       Glib::RWLock::ReaderLock lm (lock);
        require_map_to (upper);
        begin = lower_bound (_map->begin(), _map->end(), lower);
        end = upper_bound (_map->begin(), _map->end(), upper);
@@ -1449,7 +1375,7 @@ TempoMap::map (TempoMap::BBTPointList::const_iterator& begin,
 const TempoSection&
 TempoMap::tempo_section_at (framepos_t frame) const
 {
-       Glib::RWLock::ReaderLock lm (metrics_lock);
+       Glib::RWLock::ReaderLock lm (lock);
        Metrics::const_iterator i;
        TempoSection* prev = 0;
 
@@ -1495,7 +1421,7 @@ TempoMap::get_state ()
        XMLNode *root = new XMLNode ("TempoMap");
 
        {
-               Glib::RWLock::ReaderLock lm (metrics_lock);
+               Glib::RWLock::ReaderLock lm (lock);
                for (i = metrics->begin(); i != metrics->end(); ++i) {
                        root->add_child_nocopy ((*i)->get_state());
                }
@@ -1508,7 +1434,7 @@ int
 TempoMap::set_state (const XMLNode& node, int /*version*/)
 {
        {
-               Glib::RWLock::WriterLock lm (metrics_lock);
+               Glib::RWLock::WriterLock lm (lock);
 
                XMLNodeList nlist;
                XMLNodeConstIterator niter;
@@ -1561,9 +1487,10 @@ TempoMap::set_state (const XMLNode& node, int /*version*/)
                        MetricSectionSorter cmp;
                        metrics->sort (cmp);
                }
+
+               recompute_map (true, false);
        }
 
-       recompute_map (true);
        PropertyChanged (PropertyChange ());
 
        return 0;
@@ -1572,7 +1499,7 @@ TempoMap::set_state (const XMLNode& node, int /*version*/)
 void
 TempoMap::dump (std::ostream& o) const
 {
-       Glib::RWLock::ReaderLock lm (metrics_lock);
+       Glib::RWLock::ReaderLock lm (lock);
        const MeterSection* m;
        const TempoSection* t;
 
@@ -1591,7 +1518,7 @@ TempoMap::dump (std::ostream& o) const
 int
 TempoMap::n_tempos() const
 {
-       Glib::RWLock::ReaderLock lm (metrics_lock);
+       Glib::RWLock::ReaderLock lm (lock);
        int cnt = 0;
 
        for (Metrics::const_iterator i = metrics->begin(); i != metrics->end(); ++i) {
@@ -1606,7 +1533,7 @@ TempoMap::n_tempos() const
 int
 TempoMap::n_meters() const
 {
-       Glib::RWLock::ReaderLock lm (metrics_lock);
+       Glib::RWLock::ReaderLock lm (lock);
        int cnt = 0;
 
        for (Metrics::const_iterator i = metrics->begin(); i != metrics->end(); ++i) {
@@ -1621,14 +1548,93 @@ TempoMap::n_meters() const
 void
 TempoMap::insert_time (framepos_t where, framecnt_t amount)
 {
-       Glib::RWLock::WriterLock lm (metrics_lock);
-       for (Metrics::iterator i = metrics->begin(); i != metrics->end(); ++i) {
-               if ((*i)->frame() >= where && (*i)->movable ()) {
-                       (*i)->set_frame ((*i)->frame() + amount);
+       {
+               Glib::RWLock::WriterLock lm (lock);
+               for (Metrics::iterator i = metrics->begin(); i != metrics->end(); ++i) {
+                       if ((*i)->frame() >= where && (*i)->movable ()) {
+                               (*i)->set_frame ((*i)->frame() + amount);
+                       }
                }
+
+               /* now reset the BBT time of all metrics, based on their new
+                * audio time. This is the only place where we do this reverse
+                * timestamp.
+                */
+
+               Metrics::iterator i;
+               const MeterSection* meter;
+               const TempoSection* tempo;
+               MeterSection *m;
+               TempoSection *t;
+               
+               meter = &first_meter ();
+               tempo = &first_tempo ();
+               
+               BBT_Time start;
+               BBT_Time end;
+               
+               // cerr << "\n###################### TIMESTAMP via AUDIO ##############\n" << endl;
+               
+               bool first = true;
+               MetricSection* prev = 0;
+               
+               for (i = metrics->begin(); i != metrics->end(); ++i) {
+                       
+                       BBT_Time bbt;
+                       TempoMetric metric (*meter, *tempo);
+                       
+                       if (prev) {
+                               metric.set_start (prev->start());
+                               metric.set_frame (prev->frame());
+                       } else {
+                               // metric will be at frames=0 bbt=1|1|0 by default
+                               // which is correct for our purpose
+                       }
+                       
+                       BBTPointList::const_iterator bi = bbt_before_or_at ((*i)->frame());
+                       bbt_time ((*i)->frame(), bbt, bi);
+                       
+                       // cerr << "timestamp @ " << (*i)->frame() << " with " << bbt.bars << "|" << bbt.beats << "|" << bbt.ticks << " => ";
+                       
+                       if (first) {
+                               first = false;
+                       } else {
+                               
+                               if (bbt.ticks > BBT_Time::ticks_per_bar_division/2) {
+                                       /* round up to next beat */
+                                       bbt.beats += 1;
+                               }
+                               
+                               bbt.ticks = 0;
+                               
+                               if (bbt.beats != 1) {
+                                       /* round up to next bar */
+                                       bbt.bars += 1;
+                                       bbt.beats = 1;
+                               }
+                       }
+                       
+                       // cerr << bbt << endl;
+                       
+                       (*i)->set_start (bbt);
+                       
+                       if ((t = dynamic_cast<TempoSection*>(*i)) != 0) {
+                               tempo = t;
+                               // cerr << "NEW TEMPO, frame = " << (*i)->frame() << " start = " << (*i)->start() <<endl;
+                       } else if ((m = dynamic_cast<MeterSection*>(*i)) != 0) {
+                               meter = m;
+                               // cerr << "NEW METER, frame = " << (*i)->frame() << " start = " << (*i)->start() <<endl;
+                       } else {
+                               fatal << _("programming error: unhandled MetricSection type") << endmsg;
+                               /*NOTREACHED*/
+                       }
+                       
+                       prev = (*i);
+               }
+               
+               recompute_map (true, false);
        }
 
-       timestamp_metrics_from_audio_time ();
 
        PropertyChanged (PropertyChange ());
 }
@@ -1652,7 +1658,7 @@ TempoMap::framepos_minus_beats (framepos_t pos, Evoral::MusicalTime beats)
 framepos_t
 TempoMap::framepos_minus_bbt (framepos_t pos, BBT_Time op)
 {
-       Glib::RWLock::ReaderLock lm (map_lock);
+       Glib::RWLock::ReaderLock lm (lock);
        BBTPointList::const_iterator i;
        framecnt_t extra_frames = 0;
        bool had_bars = (op.bars != 0);
@@ -1707,7 +1713,7 @@ TempoMap::framepos_minus_bbt (framepos_t pos, BBT_Time op)
 framepos_t
 TempoMap::framepos_plus_bbt (framepos_t pos, BBT_Time op)
 {
-       Glib::RWLock::ReaderLock lm (map_lock);
+       Glib::RWLock::ReaderLock lm (lock);
        BBT_Time op_copy (op);
        int additional_minutes = 1;
        BBTPointList::const_iterator i;
@@ -1777,7 +1783,7 @@ TempoMap::framepos_plus_bbt (framepos_t pos, BBT_Time op)
 Evoral::MusicalTime
 TempoMap::framewalk_to_beats (framepos_t pos, framecnt_t distance)
 {
-       Glib::RWLock::ReaderLock lm (map_lock);
+       Glib::RWLock::ReaderLock lm (lock);
        BBTPointList::const_iterator i = bbt_after_or_at (pos);
        Evoral::MusicalTime beats = 0;
        framepos_t end = pos + distance;
@@ -1812,17 +1818,15 @@ TempoMap::framewalk_to_beats (framepos_t pos, framecnt_t distance)
 TempoMap::BBTPointList::const_iterator
 TempoMap::bbt_before_or_at (framepos_t pos)
 {
+       /* CALLER MUST HOLD READ LOCK */
        BBTPointList::const_iterator i;
 
        require_map_to (pos);
-       {
-               Glib::RWLock::ReaderLock lm (map_lock);
-               i = lower_bound (_map->begin(), _map->end(), pos);
-               assert (i != _map->end());
-               if ((*i).frame > pos) {
-                       assert (i != _map->begin());
-                       --i;
-               }
+       i = lower_bound (_map->begin(), _map->end(), pos);
+       assert (i != _map->end());
+       if ((*i).frame > pos) {
+               assert (i != _map->begin());
+               --i;
        }
        return i;
 }
@@ -1830,14 +1834,13 @@ TempoMap::bbt_before_or_at (framepos_t pos)
 TempoMap::BBTPointList::const_iterator
 TempoMap::bbt_after_or_at (framepos_t pos)
 {
+       /* CALLER MUST HOLD READ LOCK */
+
        BBTPointList::const_iterator i;
 
        require_map_to (pos);
-       {
-               Glib::RWLock::ReaderLock lm (map_lock);
-               i = upper_bound (_map->begin(), _map->end(), pos);
-               assert (i != _map->end());
-       }
+       i = upper_bound (_map->begin(), _map->end(), pos);
+       assert (i != _map->end());
        return i;
 }
 
@@ -1850,13 +1853,14 @@ struct bbtcmp {
 TempoMap::BBTPointList::const_iterator
 TempoMap::bbt_point_for (const BBT_Time& bbt)
 {
+       /* CALLER MUST HOLD READ LOCK */
+
        BBTPointList::const_iterator i;
        bbtcmp cmp;
        int additional_minutes = 1;
 
        while (1) {
                {
-                       Glib::RWLock::ReaderLock lm (map_lock);
                        if (!_map->empty() && _map->back().bar >= (bbt.bars + 1)) {
                                break;
                        }
@@ -1866,11 +1870,8 @@ TempoMap::bbt_point_for (const BBT_Time& bbt)
                additional_minutes *= 2;
        }
 
-       {
-               Glib::RWLock::ReaderLock lm (map_lock);
-               i = lower_bound (_map->begin(), _map->end(), bbt, cmp);
-               assert (i != _map->end());
-       }
+       i = lower_bound (_map->begin(), _map->end(), bbt, cmp);
+       assert (i != _map->end());
 
        return i;
 }