WIP memdb system

x/cosmostest/memdb/README.md

@@ -0,0 +1,18 @@
+# MemDB
+
+## Bidding Flow
+
+```mermaid
+flowchart 
+
+s[Submit Bid] --> rdb{{Read MemBids}} --> h{Is Highest Bid?} 
+
+h -- Yes --> m{{Add to MemBids}}
+h -- No --> re1[[Error]]
+
+m -- Every Block --> ae{Auction expired?}
+ae -- Yes --> fh{{Find Highest Bid}}
+ae -- No --> ca{{Check again}} -- Next block --> ae
+
+fh -- Settle --> scs[(Chain State)]
+```

x/cosmostest/memdb/biddb.go

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+package memdb
+
+import (
+	"bytes"
+	"cosmos-test/x/cosmostest/types"
+	"encoding/gob"
+	"log"
+	"math/big"
+
+	"github.com/dgraph-io/badger/v3"
+)
+
+type bidDB struct {
+	db *badger.DB
+}
+
+var BidDB bidDB
+
+// Mount Db & initialize encoder/decoder
+func (b *bidDB) Mount() {
+	db, err := badger.Open(badger.DefaultOptions("").WithInMemory(true))
+	if err != nil {
+		// must force crash here, since db is absolutely required
+		log.Fatalf("Failed to mount in-memory db: %s", err)
+	}
+	b.db = db
+
+	// initialize encode/decode stuff
+	gob.Register([]types.Bid{})
+}
+
+// Add a bid to the bid list under specified auction key.
+func (b *bidDB) AddBid(auctionId string, bid *types.Bid) error {
+	buf := bytes.NewBuffer([]byte{})
+	enc := gob.NewEncoder(buf)
+	dec := gob.NewDecoder(buf)
+	k := []byte(auctionId)
+
+	err := b.db.Update(func(txn *badger.Txn) error {
+		var bids []*types.Bid
+		bidsOld, err := txn.Get(k)
+		if err == badger.ErrKeyNotFound {
+			// key not found -> just create a new Bid array
+			bids = []*types.Bid{}
+		} else {
+			if err != nil {
+				return err
+			}
+			// key found -> decode contents to bids
+			bidsOld.Value(func(val []byte) error {
+				buf.Reset()
+				if _, err := buf.Read(val); err != nil {
+					return err
+				}
+				if err := dec.Decode(&bids); err != nil {
+					return err
+				}
+				return nil
+			})
+		}
+
+		// append bid
+		bids = append(bids, bid)
+		// encode new list
+		buf.Reset()
+		if err := enc.Encode(&bids); err != nil {
+			return err
+		}
+		// set under auction key in db
+		if err := txn.Set(k, buf.Bytes()); err != nil {
+			return err
+		}
+
+		return nil
+	})
+
+	return err
+}
+
+// Get the highest bid in the list under specified auction key.
+func (b *bidDB) GetHighestBid(auctionId string) (*types.Bid, error) {
+	k := []byte(auctionId)
+	buf := bytes.NewBuffer([]byte{})
+	dec := gob.NewDecoder(buf)
+
+	var bid *types.Bid
+
+	err := b.db.View(func(txn *badger.Txn) error {
+		bidData, err := txn.Get(k)
+		if err != nil {
+			return err
+		}
+
+		err = bidData.Value(func(val []byte) error {
+			buf.Reset()
+			if _, err := buf.Read(val); err != nil {
+				return err
+			}
+			// panic(len(val))
+
+			var bids []*types.Bid
+			if err := dec.Decode(&bids); err != nil {
+				return err
+			}
+
+			amt := big.NewInt(0)
+			rAmt := big.NewInt(0)
+			for _, rBid := range bids {
+				if bid == nil {
+					bid = rBid
+					amt.SetString(rBid.Amount, 10)
+				} else {
+					rAmt.SetString(rBid.Amount, 10)
+					if rAmt.Cmp(amt) == 1 {
+						bid = rBid
+					}
+				}
+			}
+			return nil
+		})
+
+		return err
+	})
+
+	return bid, err
+}

x/cosmostest/memdb/biddb_test.go

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+package memdb
+
+import (
+	"cosmos-test/x/cosmostest/types"
+	"testing"
+)
+
+func TestBasicFlow(t *testing.T) {
+	// this should panic if there's a problem
+	BidDB.Mount()
+
+	// add a bid
+	testBid := &types.Bid{
+		Owner:  "cosmos123",
+		Amount: "100",
+	}
+	if err := BidDB.AddBid("0", testBid); err != nil {
+		panic(err)
+	}
+
+	// // add a duplicate bid (won't check amount)
+	// if err := BidDB.AddBid("0", testBid); err != nil {
+	// 	panic(err)
+	// }
+
+	if bid, err := BidDB.GetHighestBid("0"); err != nil {
+		panic(err)
+	} else {
+		panic(bid)
+	}
+}