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https://github.com/isar/libmdbx.git
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mdbx: refine/simplify mdbx_find_oldest().
Simplify b6f14780e381300beaf782fa74252b791aae082e
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parent
1a27e40701
commit
d4bf0a3332
41
src/mdbx.c
41
src/mdbx.c
@ -1564,43 +1564,25 @@ static txnid_t mdbx_find_oldest(MDBX_txn *txn) {
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return edge;
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const uint32_t nothing_changed = MDBX_STRING_TETRAD("None");
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const uint32_t no_readers = MDBX_STRING_TETRAD("Void");
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const uint32_t snap_readers_refresh_flag = lck->mti_readers_refresh_flag;
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mdbx_jitter4testing(false);
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if (snap_readers_refresh_flag == nothing_changed)
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return last_oldest;
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if (snap_readers_refresh_flag == no_readers) {
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mdbx_notice("no-reareds, update oldest %" PRIaTXN " -> %" PRIaTXN,
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last_oldest, edge);
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mdbx_tassert(txn, edge >= lck->mti_oldest);
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return lck->mti_oldest = edge;
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}
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unsigned pending = 0;
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txnid_t oldest = edge;
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while (true) {
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lck->mti_readers_refresh_flag = nothing_changed;
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mdbx_coherent_barrier();
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const unsigned snap_nreaders = lck->mti_numreaders;
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for (unsigned i = 0; i < snap_nreaders; ++i) {
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if (lck->mti_readers[i].mr_pid) {
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/* mdbx_jitter4testing(true); */
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const txnid_t snap = lck->mti_readers[i].mr_txnid;
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pending += (snap < ~(txnid_t)0);
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if (oldest > snap && last_oldest <= /* ignore pending updates */ snap) {
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oldest = snap;
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if (oldest == last_oldest)
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return oldest;
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}
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lck->mti_readers_refresh_flag = nothing_changed;
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mdbx_coherent_barrier();
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const unsigned snap_nreaders = lck->mti_numreaders;
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for (unsigned i = 0; i < snap_nreaders; ++i) {
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if (lck->mti_readers[i].mr_pid) {
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/* mdbx_jitter4testing(true); */
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const txnid_t snap = lck->mti_readers[i].mr_txnid;
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if (oldest > snap && last_oldest <= /* ignore pending updates */ snap) {
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oldest = snap;
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if (oldest == last_oldest)
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return oldest;
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}
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}
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if (unlikely(lck->mti_readers_refresh_flag != nothing_changed))
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continue;
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if (pending > 0 ||
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mdbx_atomic_compare_and_swap32(&lck->mti_readers_refresh_flag,
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nothing_changed, no_readers))
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break;
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}
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if (oldest != last_oldest) {
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@ -3762,6 +3744,7 @@ int mdbx_txn_commit(MDBX_txn *txn) {
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}
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if (unlikely(rc != MDBX_SUCCESS))
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goto fail;
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env->me_lck->mti_readers_refresh_flag = false;
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end_mode = MDBX_END_COMMITTED | MDBX_END_UPDATE | MDBX_END_EOTDONE;
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done:
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