From: Steinar H. Gunderson <sgunderson@bigfoot.com>
Date: Sun, 8 Sep 2013 16:18:14 +0000 (+0200)
Subject: Reduce contention of queued_data_mutex.
X-Git-Tag: 1.0.1~10
X-Git-Url: https://git.sesse.net/?a=commitdiff_plain;h=9b8129d05b5d1ec0caed09a40f170e967afc60b3;hp=9b8129d05b5d1ec0caed09a40f170e967afc60b3;p=cubemap

Reduce contention of queued_data_mutex.

Seemingly holding queued_data_mutex over add_data_raw(), which does writev(),
could be slow on systems where /tmp is not on tmpfs, causing the queued_data_mutex
to be held for so long (up to a second has been observed) that the input thread
couldn't keep up.

To fix this, we move queued_data_mutex into a per-stream variable (not sure
if it's ideal, but it was the simplest way to avoid ugliness), and then hold it
for as short as possible in process_queued_data().

While we're at it, document that queued_data_last_starting_point has the same
locking rules as queued_data.
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