Method _addToCache

db/change_cache.go:837–872

Adds an entry to the appropriate channels' caches, returning the affected channels. lateSequence flag indicates whether it was a change arriving out of sequence

(ctx context.Context, change *LogEntry)

// Adds an entry to the appropriate channels' caches, returning the affected channels.  lateSequence
// flag indicates whether it was a change arriving out of sequence
func (c *changeCache) _addToCache(ctx context.Context, change *LogEntry) []channels.ID {

	if change.Sequence >= c.nextSequence {
		c.nextSequence = change.Sequence + 1
	}
	// check if change is unused sequence range
	if change.EndSequence != 0 {
		c.nextSequence = change.EndSequence + 1
	}
	delete(c.receivedSeqs, change.Sequence)

	// If unused sequence, notify the cache and return
	if change.UnusedSequence {
		c.channelCache.AddUnusedSequence(change)
		return nil
	}

	if change.IsPrincipal {
		c.channelCache.AddPrincipal(change)
		return nil
	}

	// updatedChannels tracks the set of channels that should be notified of the change.  This includes
	// the change's active channels, as well as any channel removals for the active revision.
	updatedChannels := c.channelCache.AddToCache(ctx, change)
	if base.LogDebugEnabled(ctx, base.KeyChanges) {
		base.DebugfCtx(ctx, base.KeyChanges, " #%d ==> channels %v", change.Sequence, base.UD(updatedChannels))
	}

	if change.TimeReceived != 0 {
		c.db.DbStats.Database().DCPCachingCount.Add(1)
		c.db.DbStats.Database().DCPCachingTime.Add(change.TimeReceived.Since())
	}

	return updatedChannels
}

// _addPendingLogs Add the first change(s) from pendingLogs if they're the next sequence.  If not, and we've been
// waiting too long for nextSequence, move nextSequence to skipped queue.