401 lines
15 KiB
Go
401 lines
15 KiB
Go
package lmdb
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import (
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"bytes"
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"encoding/binary"
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"fmt"
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"iter"
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"log"
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"slices"
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"fiatjaf.com/nostr"
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"fiatjaf.com/nostr/eventstore/codec/betterbinary"
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"fiatjaf.com/nostr/eventstore/internal"
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"github.com/PowerDNS/lmdb-go/lmdb"
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)
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func (b *LMDBBackend) QueryEvents(filter nostr.Filter) iter.Seq[nostr.Event] {
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return func(yield func(nostr.Event) bool) {
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if filter.Search != "" {
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return
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}
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// max number of events we'll return
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var limit int
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limit = b.MaxLimit / 4
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if filter.Limit > 0 && filter.Limit <= b.MaxLimit {
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limit = filter.Limit
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}
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if tlimit := nostr.GetTheoreticalLimit(filter); tlimit == 0 {
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return
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} else if tlimit > 0 {
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limit = tlimit
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}
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b.lmdbEnv.View(func(txn *lmdb.Txn) error {
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txn.RawRead = true
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results, err := b.query(txn, filter, limit)
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for _, ie := range results {
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if !yield(ie.Event) {
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break
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}
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}
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return err
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})
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}
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}
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func (b *LMDBBackend) query(txn *lmdb.Txn, filter nostr.Filter, limit int) ([]internal.IterEvent, error) {
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queries, extraAuthors, extraKinds, extraTagKey, extraTagValues, since, err := b.prepareQueries(filter)
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if err != nil {
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return nil, err
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}
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iterators := make([]*iterator, len(queries))
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exhausted := make([]bool, len(queries)) // indicates that a query won't be used anymore
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results := make([][]internal.IterEvent, len(queries))
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pulledPerQuery := make([]int, len(queries))
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// these are kept updated so we never pull from the iterator that is at further distance
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// (i.e. the one that has the oldest event among all)
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// we will continue to pull from it as soon as some other iterator takes the position
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oldest := internal.IterEvent{Q: -1}
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sndPhase := false // after we have gathered enough events we will change the way we iterate
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secondBatch := make([][]internal.IterEvent, 0, len(queries)+1)
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sndPhaseParticipants := make([]int, 0, len(queries)+1)
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// while merging results in the second phase we will alternate between these two lists
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// to avoid having to create new lists all the time
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var sndPhaseResultsA []internal.IterEvent
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var sndPhaseResultsB []internal.IterEvent
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var sndPhaseResultsToggle bool // this is just a dummy thing we use to keep track of the alternating
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var sndPhaseHasResultsPending bool
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remainingUnexhausted := len(queries) // when all queries are exhausted we can finally end this thing
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batchSizePerQuery := internal.BatchSizePerNumberOfQueries(limit, remainingUnexhausted)
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firstPhaseTotalPulled := 0
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exhaust := func(q int) {
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exhausted[q] = true
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remainingUnexhausted--
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if q == oldest.Q {
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oldest = internal.IterEvent{Q: -1}
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}
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}
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var firstPhaseResults []internal.IterEvent
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for q := range queries {
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cursor, err := txn.OpenCursor(queries[q].dbi)
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if err != nil {
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return nil, err
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}
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iterators[q] = &iterator{cursor: cursor}
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defer cursor.Close()
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iterators[q].seek(queries[q].startingPoint)
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results[q] = make([]internal.IterEvent, 0, batchSizePerQuery*2)
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}
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// fmt.Println("queries", filter, len(queries))
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for c := 0; ; c++ {
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batchSizePerQuery = internal.BatchSizePerNumberOfQueries(limit, remainingUnexhausted)
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// fmt.Println(" iteration", c, "remaining", remainingUnexhausted, "batchsize", batchSizePerQuery)
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// we will go through all the iterators in batches until we have pulled all the required results
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for q, query := range queries {
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if exhausted[q] {
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continue
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}
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if oldest.Q == q && remainingUnexhausted > 1 {
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continue
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}
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// fmt.Println(" query", q, unsafe.Pointer(&results[q]), b.dbiName(query.dbi), hex.EncodeToString(query.prefix), len(results[q]))
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it := iterators[q]
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pulledThisIteration := 0
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for {
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// we already have a k and a v and an err from the cursor setup, so check and use these
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if it.err != nil ||
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len(it.key) != query.keySize ||
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!bytes.HasPrefix(it.key, query.prefix) {
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// either iteration has errored or we reached the end of this prefix
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// fmt.Println(" reached end", it.key, query.keySize, query.prefix)
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exhaust(q)
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break
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}
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// "id" indexes don't contain a timestamp
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if query.timestampSize == 4 {
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createdAt := binary.BigEndian.Uint32(it.key[len(it.key)-4:])
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if createdAt < since {
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// fmt.Println(" reached since", createdAt, "<", since)
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exhaust(q)
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break
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}
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}
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// fetch actual event
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val, err := txn.Get(b.rawEventStore, it.valIdx)
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if err != nil {
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log.Printf(
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"lmdb: failed to get %x based on prefix %x, index key %x from raw event store: %s\n",
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it.valIdx, query.prefix, it.key, err)
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return nil, fmt.Errorf("iteration error: %w", err)
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}
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// check it against pubkeys without decoding the entire thing
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if extraAuthors != nil && !slices.Contains(extraAuthors, [32]byte(val[32:64])) {
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it.next()
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continue
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}
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// check it against kinds without decoding the entire thing
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if extraKinds != nil && !slices.Contains(extraKinds, [2]byte(val[132:134])) {
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it.next()
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continue
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}
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// decode the entire thing
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event := nostr.Event{}
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if err := betterbinary.Unmarshal(val, &event); err != nil {
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log.Printf("lmdb: value read error (id %x) on query prefix %x sp %x dbi %d: %s\n", val[0:32],
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query.prefix, query.startingPoint, query.dbi, err)
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return nil, fmt.Errorf("event read error: %w", err)
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}
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// fmt.Println(" event", hex.EncodeToString(val[0:4]), "kind", binary.BigEndian.Uint16(val[132:134]), "author", hex.EncodeToString(val[32:36]), "ts", nostr.Timestamp(binary.BigEndian.Uint32(val[128:132])), hex.EncodeToString(it.key), it.valIdx)
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// if there is still a tag to be checked, do it now
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if extraTagValues != nil && !event.Tags.ContainsAny(extraTagKey, extraTagValues) {
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it.next()
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continue
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}
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// this event is good to be used
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evt := internal.IterEvent{Event: event, Q: q}
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//
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//
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if sndPhase {
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// do the process described below at HIWAWVRTP.
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// if we've reached here this means we've already passed the `since` check.
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// now we have to eliminate the event currently at the `since` threshold.
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nextThreshold := firstPhaseResults[len(firstPhaseResults)-2]
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if oldest.Event.ID == nostr.ZeroID {
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// fmt.Println(" b1", evt.ID[0:8])
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// BRANCH WHEN WE DON'T HAVE THE OLDEST EVENT (BWWDHTOE)
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// when we don't have the oldest set, we will keep the results
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// and not change the cutting point -- it's bad, but hopefully not that bad.
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results[q] = append(results[q], evt)
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sndPhaseHasResultsPending = true
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} else if nextThreshold.CreatedAt > oldest.CreatedAt {
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// fmt.Println(" b2", nextThreshold.CreatedAt, ">", oldest.CreatedAt, evt.ID[0:8])
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// one of the events we have stored is the actual next threshold
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// eliminate last, update since with oldest
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firstPhaseResults = firstPhaseResults[0 : len(firstPhaseResults)-1]
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since = uint32(oldest.CreatedAt)
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// fmt.Println(" new since", since, evt.ID[0:8])
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// we null the oldest Event as we can't rely on it anymore
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// (we'll fall under BWWDHTOE above) until we have a new oldest set.
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oldest = internal.IterEvent{Q: -1}
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// anything we got that would be above this won't trigger an update to
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// the oldest anyway, because it will be discarded as being after the limit.
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//
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// finally
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// add this to the results to be merged later
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results[q] = append(results[q], evt)
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sndPhaseHasResultsPending = true
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} else if nextThreshold.CreatedAt < evt.CreatedAt {
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// the next last event in the firstPhaseResults is the next threshold
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// fmt.Println(" b3", nextThreshold.CreatedAt, "<", oldest.CreatedAt, evt.ID[0:8])
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// eliminate last, update since with the antelast
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firstPhaseResults = firstPhaseResults[0 : len(firstPhaseResults)-1]
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since = uint32(nextThreshold.CreatedAt)
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// fmt.Println(" new since", since)
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// add this to the results to be merged later
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results[q] = append(results[q], evt)
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sndPhaseHasResultsPending = true
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// update the oldest event
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if evt.CreatedAt < oldest.CreatedAt {
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oldest = evt
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}
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} else {
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// fmt.Println(" b4", evt.ID[0:8])
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// oops, _we_ are the next `since` threshold
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firstPhaseResults[len(firstPhaseResults)-1] = evt
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since = uint32(evt.CreatedAt)
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// fmt.Println(" new since", since)
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// do not add us to the results to be merged later
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// as we're already inhabiting the firstPhaseResults slice
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}
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} else {
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results[q] = append(results[q], evt)
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firstPhaseTotalPulled++
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// update the oldest event
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if oldest.Event.ID == nostr.ZeroID || evt.CreatedAt < oldest.CreatedAt {
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oldest = evt
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}
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}
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pulledPerQuery[q]++
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pulledThisIteration++
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if pulledThisIteration > batchSizePerQuery {
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// batch filled
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it.next()
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// fmt.Println(" filled", hex.EncodeToString(it.key), it.valIdx)
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break
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}
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if pulledPerQuery[q] >= limit {
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// batch filled + reached limit for this query (which is the global limit)
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exhaust(q)
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it.next()
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break
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}
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it.next()
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}
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}
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// we will do this check if we don't accumulated the requested number of events yet
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// fmt.Println("oldest", oldest.Event, "from iter", oldest.Q)
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if sndPhase && sndPhaseHasResultsPending && (oldest.Event.ID == nostr.ZeroID || remainingUnexhausted == 0) {
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// fmt.Println("second phase aggregation!")
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// when we are in the second phase we will aggressively aggregate results on every iteration
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//
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secondBatch = secondBatch[:0]
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for s := 0; s < len(sndPhaseParticipants); s++ {
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q := sndPhaseParticipants[s]
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if len(results[q]) > 0 {
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secondBatch = append(secondBatch, results[q])
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}
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if exhausted[q] {
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sndPhaseParticipants = internal.SwapDelete(sndPhaseParticipants, s)
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s--
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}
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}
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// every time we get here we will alternate between these A and B lists
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// combining everything we have into a new partial results list.
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// after we've done that we can again set the oldest.
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// fmt.Println(" xxx", sndPhaseResultsToggle)
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if sndPhaseResultsToggle {
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secondBatch = append(secondBatch, sndPhaseResultsB)
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sndPhaseResultsA = internal.MergeSortMultiple(secondBatch, limit, sndPhaseResultsA)
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oldest = sndPhaseResultsA[len(sndPhaseResultsA)-1]
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// fmt.Println(" new aggregated a", len(sndPhaseResultsB))
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} else {
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secondBatch = append(secondBatch, sndPhaseResultsA)
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sndPhaseResultsB = internal.MergeSortMultiple(secondBatch, limit, sndPhaseResultsB)
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oldest = sndPhaseResultsB[len(sndPhaseResultsB)-1]
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// fmt.Println(" new aggregated b", len(sndPhaseResultsB))
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}
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sndPhaseResultsToggle = !sndPhaseResultsToggle
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since = uint32(oldest.CreatedAt)
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// fmt.Println(" new since", since)
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// reset the `results` list so we can keep using it
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results = results[:len(queries)]
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for _, q := range sndPhaseParticipants {
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results[q] = results[q][:0]
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}
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} else if !sndPhase && firstPhaseTotalPulled >= limit && remainingUnexhausted > 0 {
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// fmt.Println("have enough!", firstPhaseTotalPulled, "/", limit, "remaining", remainingUnexhausted)
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// we will exclude this oldest number as it is not relevant anymore
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// (we now want to keep track only of the oldest among the remaining iterators)
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oldest = internal.IterEvent{Q: -1}
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// HOW IT WORKS AFTER WE'VE REACHED THIS POINT (HIWAWVRTP)
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// now we can combine the results we have and check what is our current oldest event.
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// we also discard anything that is after the current cutting point (`limit`).
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// so if we have [1,2,3], [10, 15, 20] and [7, 21, 49] but we only want 6 total
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// we can just keep [1,2,3,7,10,15] and discard [20, 21, 49],
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// and also adjust our `since` parameter to `15`, discarding anything we get after it
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// and immediately declaring that iterator exhausted.
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// also every time we get result that is more recent than this updated `since` we can
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// keep it but also discard the previous since, moving the needle one back -- for example,
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// if we get an `8` we can keep it and move the `since` parameter to `10`, discarding `15`
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// in the process.
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all := make([][]internal.IterEvent, len(results))
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copy(all, results) // we have to use this otherwise internal.MergeSortMultiple will scramble our results slice
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firstPhaseResults = internal.MergeSortMultiple(all, limit, nil)
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oldest = firstPhaseResults[limit-1]
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since = uint32(oldest.CreatedAt)
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// fmt.Println("new since", since)
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for q := range queries {
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if exhausted[q] {
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continue
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}
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// we also automatically exhaust any of the iterators that have already passed the
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// cutting point (`since`)
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if results[q][len(results[q])-1].CreatedAt < oldest.CreatedAt {
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exhausted[q] = true
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remainingUnexhausted--
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continue
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}
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// for all the remaining iterators,
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// since we have merged all the events in this `firstPhaseResults` slice, we can empty the
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// current `results` slices and reuse them.
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results[q] = results[q][:0]
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// build this index of indexes with everybody who remains
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sndPhaseParticipants = append(sndPhaseParticipants, q)
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}
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// we create these two lists and alternate between them so we don't have to create a
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// a new one every time
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sndPhaseResultsA = make([]internal.IterEvent, 0, limit*2)
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sndPhaseResultsB = make([]internal.IterEvent, 0, limit*2)
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// from now on we won't run this block anymore
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sndPhase = true
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}
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// fmt.Println("remaining", remainingUnexhausted)
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if remainingUnexhausted == 0 {
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break
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}
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}
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// fmt.Println("is sndPhase?", sndPhase)
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var combinedResults []internal.IterEvent
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if sndPhase {
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// fmt.Println("ending second phase")
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// when we reach this point either sndPhaseResultsA or sndPhaseResultsB will be full of stuff,
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// the other will be empty
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var sndPhaseResults []internal.IterEvent
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// fmt.Println("xxx", sndPhaseResultsToggle, len(sndPhaseResultsA), len(sndPhaseResultsB))
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if sndPhaseResultsToggle {
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sndPhaseResults = sndPhaseResultsB
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combinedResults = sndPhaseResultsA[0:limit] // reuse this
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// fmt.Println(" using b", len(sndPhaseResultsA))
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} else {
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sndPhaseResults = sndPhaseResultsA
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combinedResults = sndPhaseResultsB[0:limit] // reuse this
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// fmt.Println(" using a", len(sndPhaseResultsA))
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}
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all := [][]internal.IterEvent{firstPhaseResults, sndPhaseResults}
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combinedResults = internal.MergeSortMultiple(all, limit, combinedResults)
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// fmt.Println("final combinedResults", len(combinedResults), cap(combinedResults), limit)
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} else {
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combinedResults = make([]internal.IterEvent, limit)
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combinedResults = internal.MergeSortMultiple(results, limit, combinedResults)
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}
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return combinedResults, nil
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}
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