support MultiGet operation #80
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@ngaut PTAL |
levels.go
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| if pair.found { | ||
| continue | ||
| } | ||
| val, err := h.get(pair.key) // Calls h.RLock() and h.RUnlock(). |
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Can we reduce calling of RLock and RUnlock?
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We can move the getTablesForKey and decrTableRef out of h.get, then move RLock out of getTablesForKey, but after I do it, I found the code become much harder to read.
So I prefer not to do so.
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I'll try another way to do it.
db.go
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| }() | ||
| y.NumGets.Add(int64(len(pairs))) | ||
| var foundCount int | ||
| for i := 0; i < len(tables); i++ { |
| y.NumGets.Add(int64(len(pairs))) | ||
| var foundCount int | ||
| for _, table := range tables { | ||
| for j := range pairs { |
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This way, we cannot modify the pair in the slice because the pair is a value, not a pointer.
| var expectedValues []string | ||
| for i := 0; i < n; i += 100 { | ||
| multiGetKeys = append(multiGetKeys, data(i)) | ||
| expectedValues = append(expectedValues, fmt.Sprintf("zzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzz%9d", i)) |
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Remove "zzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzz"
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This test needs the value to be large enough, so there would be multiple levels in DB.
level_handler.go
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| if th.DoesNotHave(keyNoTs) { | ||
| func (s *levelHandler) decrTableRefs(tables []*table.Table) { |
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Make decrTableRefs as a pure function, so we can reuse it in multiget method.
transaction.go
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| @@ -366,6 +363,46 @@ func (txn *Txn) Get(key []byte) (item *Item, rerr error) { | |||
| return item, nil | |||
| } | |||
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| type keyValuePair struct { | |||
| key []byte | |||
| found bool | |||
level_handler.go
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| return y.ValueStruct{} | ||
| } | ||
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| func (s *levelHandler) getInTable(key []byte, th *table.Table) (result y.ValueStruct) { |
| return s.refLevel0Tables() | ||
| } | ||
| out := make([]*table.Table, len(pairs)) | ||
| for i, pair := range pairs { |
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There are some redundant tables, these tables may cause unnecessary search.
We should group by level, table, and keys. Also we do a lot of redundant work, such as recalculate key's hash when do bloom filter looking up.
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We can do more optimization in further PR.
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@ngaut PTAL |
level_handler.go
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| return []*table.Table{tbl} | ||
| } | ||
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| // refTablesForKeys return tables for pairs. |
level_handler.go
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| @@ -224,23 +234,50 @@ func (s *levelHandler) close() error { | |||
| return errors.Wrap(err, "levelHandler.close") | |||
| } | |||
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| // getTableForKey acquires a read-lock to access s.tables. It returns a list of tableHandlers. | |||
| func (s *levelHandler) getTableForKey(key []byte) []*table.Table { | |||
| // refTablesForKey acquires a read-lock to access s.tables. It returns a list of tableHandlers. | |||
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LGTM |
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