cmd/geth, consensus/ethash: add support for --miner.notify.full flag (#22558)

The PR implements the --miner.notify.full flag that enables full pending block
notifications. When this flag is used, the block notifications sent to mining
endpoints contain the complete block header JSON instead of a work package
array.

Co-authored-by: AlexSSD7 <alexandersadovskyi7@protonmail.com>
Co-authored-by: Martin Holst Swende <martin@swende.se>

consensus/ethash/sealer_test.go

@@ -22,6 +22,7 @@ import (
 	"math/big"
 	"net/http"
 	"net/http/httptest"
+	"strconv"
 	"testing"
 	"time"
 
@@ -74,6 +75,50 @@ func TestRemoteNotify(t *testing.T) {
 	}
 }
 
+// Tests whether remote HTTP servers are correctly notified of new work. (Full pending block body / --miner.notify.full)
+func TestRemoteNotifyFull(t *testing.T) {
+	// Start a simple web server to capture notifications.
+	sink := make(chan map[string]interface{})
+	server := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, req *http.Request) {
+		blob, err := ioutil.ReadAll(req.Body)
+		if err != nil {
+			t.Errorf("failed to read miner notification: %v", err)
+		}
+		var work map[string]interface{}
+		if err := json.Unmarshal(blob, &work); err != nil {
+			t.Errorf("failed to unmarshal miner notification: %v", err)
+		}
+		sink <- work
+	}))
+	defer server.Close()
+
+	// Create the custom ethash engine.
+	config := Config{
+		PowMode:    ModeTest,
+		NotifyFull: true,
+		Log:        testlog.Logger(t, log.LvlWarn),
+	}
+	ethash := New(config, []string{server.URL}, false)
+	defer ethash.Close()
+
+	// Stream a work task and ensure the notification bubbles out.
+	header := &types.Header{Number: big.NewInt(1), Difficulty: big.NewInt(100)}
+	block := types.NewBlockWithHeader(header)
+
+	ethash.Seal(nil, block, nil, nil)
+	select {
+	case work := <-sink:
+		if want := "0x" + strconv.FormatUint(header.Number.Uint64(), 16); work["number"] != want {
+			t.Errorf("pending block number mismatch: have %v, want %v", work["number"], want)
+		}
+		if want := "0x" + header.Difficulty.Text(16); work["difficulty"] != want {
+			t.Errorf("pending block difficulty mismatch: have %s, want %s", work["difficulty"], want)
+		}
+	case <-time.After(3 * time.Second):
+		t.Fatalf("notification timed out")
+	}
+}
+
 // Tests that pushing work packages fast to the miner doesn't cause any data race
 // issues in the notifications.
 func TestRemoteMultiNotify(t *testing.T) {
@@ -119,6 +164,55 @@ func TestRemoteMultiNotify(t *testing.T) {
 	}
 }
 
+// Tests that pushing work packages fast to the miner doesn't cause any data race
+// issues in the notifications. Full pending block body / --miner.notify.full)
+func TestRemoteMultiNotifyFull(t *testing.T) {
+	// Start a simple web server to capture notifications.
+	sink := make(chan map[string]interface{}, 64)
+	server := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, req *http.Request) {
+		blob, err := ioutil.ReadAll(req.Body)
+		if err != nil {
+			t.Errorf("failed to read miner notification: %v", err)
+		}
+		var work map[string]interface{}
+		if err := json.Unmarshal(blob, &work); err != nil {
+			t.Errorf("failed to unmarshal miner notification: %v", err)
+		}
+		sink <- work
+	}))
+	defer server.Close()
+
+	// Create the custom ethash engine.
+	config := Config{
+		PowMode:    ModeTest,
+		NotifyFull: true,
+		Log:        testlog.Logger(t, log.LvlWarn),
+	}
+	ethash := New(config, []string{server.URL}, false)
+	defer ethash.Close()
+
+	// Provide a results reader.
+	// Otherwise the unread results will be logged asynchronously
+	// and this can happen after the test is finished, causing a panic.
+	results := make(chan *types.Block, cap(sink))
+
+	// Stream a lot of work task and ensure all the notifications bubble out.
+	for i := 0; i < cap(sink); i++ {
+		header := &types.Header{Number: big.NewInt(int64(i)), Difficulty: big.NewInt(100)}
+		block := types.NewBlockWithHeader(header)
+		ethash.Seal(nil, block, results, nil)
+	}
+
+	for i := 0; i < cap(sink); i++ {
+		select {
+		case <-sink:
+			<-results
+		case <-time.After(10 * time.Second):
+			t.Fatalf("notification %d timed out", i)
+		}
+	}
+}
+
 // Tests whether stale solutions are correctly processed.
 func TestStaleSubmission(t *testing.T) {
 	ethash := NewTester(nil, true)