From 5f2c4d4799d33ae0e3362af3ee5055691e03e83a Mon Sep 17 00:00:00 2001 From: wm4 Date: Mon, 15 May 2017 15:48:31 +0200 Subject: cache: move duplicated condition to a function While subtly duplicating such checks happens a lot in this file, this particular case can be easily factored into a function. --- stream/cache.c | 18 ++++++++++++------ 1 file changed, 12 insertions(+), 6 deletions(-) diff --git a/stream/cache.c b/stream/cache.c index a74c58df77..16ce35337c 100644 --- a/stream/cache.c +++ b/stream/cache.c @@ -211,15 +211,21 @@ static size_t read_buffer(struct priv *s, unsigned char *dst, return read; } +// Whether a seek will be needed to get to the position. This honors seek_limit, +// which is a heuristic to prevent dropping the cache with small forward seeks. +// This helps in situations where waiting for network a bit longer would quickly +// reach the target position. Especially if the demuxer seeks back and forth, +// not dropping the backwards cache will be a major performance win. +static bool needs_seek(struct priv *s, int64_t pos) +{ + return pos < s->min_filepos || pos > s->max_filepos + s->seek_limit; +} + static bool cache_update_stream_position(struct priv *s) { int64_t read = s->read_filepos; - // drop cache contents only if seeking backward or too much fwd. - // This is also done for on-disk files, since it loses the backseek cache. - // That in turn can cause major bandwidth increase and performance - // issues with e.g. mov or badly interleaved files - if (read < s->min_filepos || read > s->max_filepos + s->seek_limit) { + if (needs_seek(s, read)) { MP_VERBOSE(s, "Dropping cache at pos %"PRId64", " "cached range: %"PRId64"-%"PRId64".\n", read, s->min_filepos, s->max_filepos); @@ -607,7 +613,7 @@ static int cache_seek(stream_t *cache, int64_t pos) // This check is not quite exact - if the reader thread is blocked in // a read, the read might advance file position enough that a seek // forward is no longer needed. - if (pos < s->min_filepos || pos > s->max_filepos + s->seek_limit) { + if (needs_seek(s, pos)) { s->eof = false; s->control = CACHE_CTRL_SEEK; s->control_res = 0; -- cgit v1.2.3