9c995fc4dd
The torrent reader used a static 5 MiB readahead — about 1.9s of a 20 Mbps 4K stream — so streaming a torrent while it downloaded outran the download and stalled. anacrolix's reader already prioritises the pieces in the readahead window ahead of the playhead (and re-prioritises on seek); the window was just too small. dynamicReadahead sizes it to ~30s of video (clamped 8-96 MiB, 24 MiB default when bitrate is unknown). The torrent provider probes the bitrate asynchronously so stream start never blocks on ffprobe; readers created after the probe resolves pick up the accurate size. Real 4K (20.7 Mbps) -> 73 MiB.
43 lines
1.5 KiB
Go
43 lines
1.5 KiB
Go
package engine
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import "testing"
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func TestDynamicReadahead(t *testing.T) {
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cases := []struct {
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name string
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bitrateBps int64
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want int64
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}{
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{"unknown bitrate → default", 0, defaultReadahead},
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{"negative → default", -1, defaultReadahead},
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{"low bitrate clamps to min", 1_000_000, minReadahead}, // 1 Mbps → ~3.75 MiB < 8 MiB
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{"mid bitrate scales", 5_000_000, 5_000_000 / 8 * readaheadSeconds}, // 5 Mbps → ~18.75 MiB
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{"high bitrate within range", 25_000_000, 25_000_000 / 8 * readaheadSeconds}, // 4K ~25 Mbps → ~93.75 MiB
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{"very high clamps to max", 80_000_000, maxReadahead}, // 80 Mbps → 300 MiB > cap
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}
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for _, c := range cases {
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t.Run(c.name, func(t *testing.T) {
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got := dynamicReadahead(c.bitrateBps)
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if got != c.want {
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t.Errorf("dynamicReadahead(%d) = %d, want %d", c.bitrateBps, got, c.want)
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}
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if got < minReadahead && c.bitrateBps > 0 {
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t.Errorf("result %d below min %d", got, minReadahead)
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}
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if got > maxReadahead {
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t.Errorf("result %d above max %d", got, maxReadahead)
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}
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})
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}
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}
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func TestDynamicReadahead_BeatsOldStatic(t *testing.T) {
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// The whole point: every result is bigger than the old static 5 MiB that
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// stalled HD/4K.
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const oldStatic = 5 * 1024 * 1024
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for _, b := range []int64{0, 1_000_000, 8_000_000, 25_000_000, 100_000_000} {
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if got := dynamicReadahead(b); got <= oldStatic {
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t.Errorf("dynamicReadahead(%d) = %d, not bigger than the old 5 MiB", b, got)
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}
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}
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}
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