From 313adc84320140723721e3d11da9060b32bacec4 Mon Sep 17 00:00:00 2001
From: George Tankersley <george.tankersley@gmail.com>
Date: Wed, 12 Dec 2018 23:27:29 +0000
Subject: [PATCH] frontend: implement GetBlockRange and GetTransaction

---
 frontend/service.go | 82 +++++++++++++++++++++++++++++++++++++++------
 storage/sqlite3.go  | 35 +++++++++----------
 2 files changed, 89 insertions(+), 28 deletions(-)

diff --git a/frontend/service.go b/frontend/service.go
index 217b831..054a99a 100644
--- a/frontend/service.go
+++ b/frontend/service.go
@@ -56,27 +56,87 @@ func (s *SqlStreamer) GetBlock(ctx context.Context, id *rpc.BlockID) (*rpc.Compa
 		return nil, ErrUnspecified
 	}
 
+	var blockBytes []byte
+	var err error
+
 	// Precedence: a hash is more specific than a height. If we have it, use it first.
 	if id.Hash != nil {
 		leHashString := hex.EncodeToString(id.Hash)
-		return storage.GetBlockByHash(ctx, s.db, leHashString)
+		blockBytes, err = storage.GetBlockByHash(ctx, s.db, leHashString)
+	} else {
+		blockBytes, err = storage.GetBlock(ctx, s.db, int(id.Height))
 	}
 
-	// we have a height and not a hash
-	if int(id.Height) > 0 {
-		return storage.GetBlock(ctx, s.db, int(id.Height))
+	if err != nil {
+		return nil, err
 	}
 
-	return nil, ErrUnspecified
+	cBlock := &rpc.CompactBlock{}
+	err = proto.Unmarshal(blockBytes, cBlock)
+	return cBlock, err
 }
 
-func (s *SqlStreamer) GetBlockRange(*rpc.BlockRange, rpc.CompactTxStreamer_GetBlockRangeServer) error {
-	return ErrNoImpl
+func (s *SqlStreamer) GetBlockRange(span *rpc.BlockRange, resp rpc.CompactTxStreamer_GetBlockRangeServer) error {
+	blocks := make(chan []byte)
+	errors := make(chan error)
+	done := make(chan bool)
+
+	timeout := resp.Context().WithTimeout(1 * time.Second)
+	go GetBlockRange(timeout, s.db, blocks, errors, done, span.Start, span.End)
+
+	for {
+		select {
+		case <-timeout.Done():
+			return timeout.Err()
+		case err := <-errors:
+			return err
+		case blockBytes := <-blocks:
+			cBlock := &rpc.CompactBlock{}
+			err = proto.Unmarshal(blockBytes, cBlock)
+			if err != nil {
+				return err // TODO really need better logging in this whole service
+			}
+			err = resp.Send(cBlock)
+			if err != nil {
+				return err
+			}
+		}
+	}
+
+	return nil
 }
 
-func (s *SqlStreamer) GetTransaction(context.Context, *rpc.TxFilter) (*rpc.RawTransaction, error) {
-	return nil, ErrNoImpl
-}
-func (s *SqlStreamer) SendTransaction(context.Context, *rpc.RawTransaction) (*rpc.SendResponse, error) {
+func (s *SqlStreamer) GetTransaction(ctx context.Context, txf *rpc.TxFilter) (*rpc.RawTransaction, error) {
+	var txBytes []byte
+	var err error
+
+	if txf.Hash != nil {
+		leHashString := hex.EncodeToString(txf.Hash)
+		txBytes, err = storage.GetFullTxByHash(ctx, s.db, leHashString)
+		if err != nil {
+			return nil, err
+		}
+		return &rpc.RawTransaction{Data: txBytes}, nil
+
+	}
+
+	if txf.Block.Hash != nil {
+		leHashString := hex.EncodeToString(txf.Hash)
+		txBytes, err = storage.GetFullTxByHashAndIndex(ctx, s.db, leHashString, int(txf.Index))
+		if err != nil {
+			return nil, err
+		}
+		return &rpc.RawTransaction{Data: txBytes}, nil
+	}
+
+	// A totally unset protobuf will attempt to fetch the genesis coinbase tx.
+	txBytes, err = storage.GetFullTxByHeightAndIndex(ctx, s.db, int(txf.Block.Height), int(txf.Index))
+	if err != nil {
+		return nil, err
+	}
+	return &rpc.RawTransaction{Data: txBytes}, nil
+}
+
+func (s *SqlStreamer) SendTransaction(ctx context.Context, rawtx *rpc.RawTransaction) (*rpc.SendResponse, error) {
 	return nil, ErrNoImpl
 }
diff --git a/storage/sqlite3.go b/storage/sqlite3.go
index 581970a..5da2123 100644
--- a/storage/sqlite3.go
+++ b/storage/sqlite3.go
@@ -83,35 +83,36 @@ func GetBlockByHash(ctx context.Context, db *sql.DB, hash string) ([]byte, error
 	return blockBytes, err
 }
 
-// [start, end]
-func GetBlockRange(conn *sql.DB, start, end int) ([][]byte, error) {
-	// TODO sanity check range bounds
-	query := "SELECT compact_encoding from blocks WHERE (height BETWEEN ? AND ?)"
-	result, err := conn.Query(query, start, end)
+// [start, end] inclusive
+func GetBlockRange(ctx context.Context, db *sql.DB, blocks chan<- []byte, errors chan<- error, start, end int) {
+	// TODO sanity check ranges, rate limit?
+	numBlocks := (end - start) + 1
+	query := "SELECT height, compact_encoding from blocks WHERE (height BETWEEN ? AND ?)"
+	result, err := db.QueryContext(ctx, query, start, end)
 	if err != nil {
-		return nil, err
+		errors <- err
+		return
 	}
 	defer result.Close()
 
-	compactBlocks := make([][]byte, 0, (end-start)+1)
+	// My assumption here is that if the context is cancelled then result.Next() will fail.
+
+	var blockBytes []byte // avoid a copy with *RawBytes
 	for result.Next() {
-		var blockBytes []byte // avoid a copy with *RawBytes
 		err = result.Scan(&blockBytes)
 		if err != nil {
-			return nil, err
+			errors <- err
+			return
 		}
-		compactBlocks = append(compactBlocks, blockBytes)
+		blocks <- blockBytes
 	}
 
-	err = result.Err()
-	if err != nil {
-		return nil, err
+	if err := result.Err(); err != nil {
+		errors <- err
 	}
 
-	if len(compactBlocks) == 0 {
-		return nil, ErrBadRange
-	}
-	return compactBlocks, nil
+	// done
+	errors <- nil
 }
 
 func StoreBlock(conn *sql.DB, height int, hash string, sapling bool, encoded []byte) error {