Introduce AudioProcessor::before_drop pre-destructor hook

[orottier]

This allows the processor to send some final events, or move some items to the garbage collector thread. This will help with #368

In this commit we use the before_drop hook to ensure that the ended event is sent for all AudioScheduledSourceNodes when the stop time is implicit. This fixes #489

[orottier]

/bench

[github-actions]

Benchmark result:


bench_ctor
  Instructions:             3326217 (-0.090261%)
  L1 Accesses:              5104643 (-0.053726%)
  L2 Accesses:                  774 (+1.842105%)
  RAM Accesses:               55238 (-0.005431%)
  Estimated Cycles:         7041843 (-0.039449%)

bench_audio_buffer_decode
  Instructions:             7373065 (No change)
  L1 Accesses:             10167885 (-0.000256%)
  L2 Accesses:                28131 (+0.096072%)
  RAM Accesses:               32201 (-0.003105%)
  Estimated Cycles:        11435575 (+0.000647%)

bench_constant_source
  Instructions:             7709084 (-0.139575%)
  L1 Accesses:             11707246 (-0.090588%)
  L2 Accesses:                  875 (+0.922722%)
  RAM Accesses:               56305 (-0.012431%)
  Estimated Cycles:        13682296 (-0.079018%)

bench_sine
  Instructions:            59346829 (-0.022955%)
  L1 Accesses:             87705382 (-0.051152%)
  L2 Accesses:               247049 (+14.77945%)
  RAM Accesses:               57015 (+0.003508%)
  Estimated Cycles:        90936152 (+0.125784%)

bench_sine_gain
  Instructions:            63822702 (-0.044885%)
  L1 Accesses:             94606058 (-0.049943%)
  L2 Accesses:               246276 (+8.428102%)
  RAM Accesses:               55248 (+0.005430%)
  Estimated Cycles:        97771118 (+0.049678%)

bench_sine_gain_delay
  Instructions:            97160784 (+0.013428%)
  L1 Accesses:            141912453 (+0.045890%)
  L2 Accesses:               444724 (-4.561774%)
  RAM Accesses:               57276 (+0.012223%)
  Estimated Cycles:       146140733 (-0.028010%)

bench_buffer_src
  Instructions:            18288868 (-0.075301%)
  L1 Accesses:             26970718 (-0.054107%)
  L2 Accesses:                81321 (+1.652521%)
  RAM Accesses:               93762 (+0.009600%)
  Estimated Cycles:        30658993 (-0.025030%)

bench_buffer_src_delay
  Instructions:            75509981 (+0.026996%)
  L1 Accesses:            106955863 (+0.045177%)
  L2 Accesses:               282317 (+1.010040%)
  RAM Accesses:               93902 (+0.015977%)
  Estimated Cycles:       111654018 (+0.056401%)

bench_buffer_src_iir
  Instructions:            79344509 (-0.021662%)
  L1 Accesses:            113879908 (-0.010619%)
  L2 Accesses:                80750 (-5.170693%)
  RAM Accesses:               93367 (+0.006427%)
  Estimated Cycles:       117551503 (-0.028829%)

bench_buffer_src_biquad
  Instructions:            56981856 (-0.056779%)
  L1 Accesses:             77391020 (-0.023634%)
  L2 Accesses:               189866 (-6.673614%)
  RAM Accesses:               93489 (+0.009628%)
  Estimated Cycles:        81612465 (-0.105100%)

bench_stereo_positional
  Instructions:            45662328 (-0.276083%)
  L1 Accesses:             69289082 (-0.236421%)
  L2 Accesses:               424993 (-1.584174%)
  RAM Accesses:               94079 (+0.013820%)
  Estimated Cycles:        74706812 (-0.264272%)

bench_stereo_panning_automation
  Instructions:            29537019 (-0.071682%)
  L1 Accesses:             44651837 (-0.052248%)
  L2 Accesses:                85102 (+3.254065%)
  RAM Accesses:               93409 (+0.003212%)
  Estimated Cycles:        48346662 (-0.020322%)

bench_analyser_node
  Instructions:            37375838 (-0.045896%)
  L1 Accesses:             52502111 (-0.033865%)
  L2 Accesses:               130255 (+1.026122%)
  RAM Accesses:               94351 (+0.004240%)
  Estimated Cycles:        56455671 (-0.019535%)

bench_hrtf_panners
  Instructions:           321982516 (-0.006385%)
  L1 Accesses:            564950099 (-0.003125%)
  L2 Accesses:             10852682 (-0.104584%)
  RAM Accesses:              120929 (-0.109036%)
  Estimated Cycles:       623446024 (-0.012684%)

bench_sine_gain_with_worklet
  Instructions:            64661655 (-0.032720%)
  L1 Accesses:             95841591 (-0.024396%)
  L2 Accesses:               217949 (+1.278828%)
  RAM Accesses:               55426 (+0.007217%)
  Estimated Cycles:        98871246 (-0.009594%)


running 0 tests

test result: ok. 0 passed; 0 failed; 0 ignored; 0 measured; 0 filtered out; finished in 0.00s

[b-ma]

Really nice!