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ircd::db: Improve row seek debugging and related.

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This commit is contained in:
Jason Volk 2019-01-11 13:46:43 -08:00
parent 11f905274e
commit 0f20a6a6ba
1 changed files with 52 additions and 23 deletions
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59
ircd/db.cc
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@ -9125,22 +9125,28 @@ ircd::db::write(const row::delta *const &begin,
write(&deltas.front(), &deltas.front() + deltas.size(), sopts);
}
// Developer can specifically use RB_DEBUG_DB_SEEK_ROW without RB_DEBUG_DB_SEEK
// to only see a report of the row seek as a whole. If RB_DEBUG_DB_SEEK is
// enabled that implies RB_DEBUG_DB_SEEK_ROW as well.
//
#if !defined(RB_DEBUG_DB_SEEK_ROW) && defined(RB_DEBUG_DB_SEEK_ROW)
#define RB_DEBUG_DB_SEEK_ROW
#endif
size_t
ircd::db::seek(row &r,
const string_view &key,
const gopts &opts)
{
#ifdef RB_DEBUG_DB_SEEK
const ircd::timer timer;
#endif
// This frame can't be interrupted because it may have requests
// pending in the request pool which must synchronize back here.
const ctx::uninterruptible ui;
// The following closure performs the seek() for a single cell in the row.
// It may be executed on another ircd::ctx if the data isn't cached and
// blocking IO is required. This frame can't be interrupted because it may
// have requests pending in the request pool which must synchronize back
// here.
size_t ret{0};
std::exception_ptr eptr;
ctx::latch latch{r.size()};
const ctx::uninterruptible ui;
const auto closure{[&opts, &latch, &ret, &key, &eptr]
(auto &cell) noexcept
{
@ -9184,18 +9190,37 @@ ircd::db::seek(row &r,
latch.count_down();
}};
#ifdef RB_DEBUG_DB_SEEK_ROW
const ircd::timer timer;
size_t submits{0};
#endif
// Submit all the requests
for(auto &cell : r)
{
db::column &column(cell);
const auto reclosure{[&closure, &cell]
() noexcept
{
closure(cell);
}};
// Whether to submit the request to another ctx or execute it here.
// Explicit option to prevent submitting must not be set. If there
// is a chance the data is already in the cache, we can avoid the
// context switching and occupation of the request pool.
//TODO: should check a bloom filter on the cache for this branch
//TODO: because right now double-querying the cache is gross.
if(!test(opts, get::NO_PARALLEL) && !exists(cache(column), key))
const bool submit
{
!test(opts, get::NO_PARALLEL) && !exists(cache(column), key)
};
#ifdef RB_DEBUG_DB_SEEK_ROW
submits += submit;
#endif
if(submit)
request(reclosure);
else
reclosure();
@ -9205,21 +9230,25 @@ ircd::db::seek(row &r,
latch.wait();
assert(ret <= r.size());
#ifdef RB_DEBUG_DB_SEEK
#ifdef RB_DEBUG_DB_SEEK_ROW
if(likely(!r.empty()))
{
const column &c(r[0]);
const database &d(c);
thread_local char tmbuf[32];
log::debug
{
log, "'%s' %lu:%lu '%s' row SEEK KEY %zu of %zu in %ld$us %s",
log, "'%s' SEEK ROW seq:%lu:%-10lu cnt:%-2zu req:%-2zu ret:%-2zu in %s %s",
name(d),
sequence(d),
sequence(r[0]),
name(c),
ret,
sequence(opts.snapshot),
r.size(),
timer.at<microseconds>().count(),
submits,
ret,
pretty(tmbuf, timer.at<microseconds>(), true),
what(eptr)
};
}
#endif
if(eptr && !test(opts, get::NO_THROW))