eth,les,miner: implement feeHistory API (ethereum#23033)

eth/api_backend.go

@@ -181,6 +181,10 @@ func (b *EthApiBackend) BlockByNumberOrHash(ctx context.Context, blockNrOrHash r
 	return nil, errors.New("invalid arguments; neither block nor hash specified")
 }
 
+func (b *EthApiBackend) PendingBlockAndReceipts() (*types.Block, types.Receipts) {
+	return b.eth.miner.PendingBlockAndReceipts()
+}
+
 func (b *EthApiBackend) StateAndHeaderByNumber(ctx context.Context, blockNr rpc.BlockNumber) (*state.StateDB, *types.Header, error) {
 	// Pending state is only known by the miner
 	if blockNr == rpc.PendingBlockNumber {

les/api_backend.go

@@ -130,6 +130,10 @@ func (b *LesApiBackend) BlockByNumberOrHash(ctx context.Context, blockNrOrHash r
 	return nil, errors.New("invalid arguments; neither block nor hash specified")
 }
 
+func (b *LesApiBackend) PendingBlockAndReceipts() (*types.Block, types.Receipts) {
+	return nil, nil
+}
+
 func (b *LesApiBackend) StateAndHeaderByNumber(ctx context.Context, blockNr rpc.BlockNumber) (*state.StateDB, *types.Header, error) {
 	header, err := b.HeaderByNumber(ctx, blockNr)
 	if header == nil || err != nil {

miner/miner.go

@@ -178,6 +178,11 @@ func (self *Miner) PendingBlock() *types.Block {
 	return self.worker.pendingBlock()
 }
 
+// PendingBlockAndReceipts returns the currently pending block and corresponding receipts.
+func (miner *Miner) PendingBlockAndReceipts() (*types.Block, types.Receipts) {
+	return miner.worker.pendingBlockAndReceipts()
+}
+
 func (self *Miner) SetEtherbase(addr common.Address) {
 	self.coinbase = addr
 	self.worker.setEtherbase(addr)

miner/worker.go

@@ -128,6 +128,10 @@ type worker struct {
 	coinbase common.Address
 	extra    []byte
 
+	snapshotMu       sync.RWMutex // The lock used to protect the block snapshot and state snapshot
+	snapshotBlock    *types.Block
+	snapshotReceipts types.Receipts
+
 	currentMu sync.Mutex
 	current   *Work
 
@@ -219,6 +223,14 @@ func (self *worker) pendingBlock() *types.Block {
 	return self.current.Block
 }
 
+// pendingBlockAndReceipts returns pending block and corresponding receipts.
+func (w *worker) pendingBlockAndReceipts() (*types.Block, types.Receipts) {
+	// return a snapshot to avoid contention on currentMu mutex
+	w.snapshotMu.RLock()
+	defer w.snapshotMu.RUnlock()
+	return w.snapshotBlock, w.snapshotReceipts
+}
+
 func (self *worker) start() {
 	self.mu.Lock()
 	defer self.mu.Unlock()