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Code Issues Releases Wiki Activity

ircd::db: Fix a rocksdb api misuse.

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This commit is contained in:
Jason Volk 2017-10-27 16:48:27 -07:00
parent 4ae58a4f46
commit bc5f429681
1 changed files with 14 additions and 4 deletions
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18
ircd/db.cc
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@ -2690,6 +2690,13 @@ ircd::db::write(column &column,
};
}
///
/// TODO: As soon as rocksdb regressed from allowing a null value argument
/// to the query, we are forced to watch rocksdb allocate and copy the value
/// into our string `discard` for no reason at all. If this regression remains
/// it may be more efficient to use a regular iterator seek like everything
/// else. Otherwise if they fix this, the discard string should become a
/// nullptr instead.
bool
ircd::db::has(column &column,
const string_view &key,
@ -2705,19 +2712,22 @@ ircd::db::has(column &column,
opts.read_tier = NON_BLOCKING;
// Perform a co-RP query to the filtration
if(!d.d->KeyMayExist(opts, c, k, nullptr, nullptr))
bool value{false};
static thread_local std::string discard;
const bool may_exist{d.d->KeyMayExist(opts, c, k, &discard, &value)};
if(!may_exist)
return false;
// Perform a query to the cache
static std::string *const null_str_ptr(nullptr);
auto status(d.d->Get(opts, c, k, null_str_ptr));
auto status(d.d->Get(opts, c, k, &discard));
if(status.IsIncomplete())
{
// DB cache miss; next query requires I/O, offload it
opts.read_tier = BLOCKING;
ctx::offload([&d, &c, &k, &opts, &status]
{
status = d.d->Get(opts, c, k, null_str_ptr);
status = d.d->Get(opts, c, k, &discard);
});
}