Issue indexer queue redis support (#6218)

* add redis queue

* finished indexer redis queue

* add redis vendor

* fix vet

* Update docs/content/doc/advanced/config-cheat-sheet.en-us.md

Co-Authored-By: lunny <xiaolunwen@gmail.com>

* switch to go mod

* Update required changes for new logging func signatures

vendor/github.com/go-redis/redis/iterator.go

@@ -0,0 +1,73 @@
+package redis
+
+import "sync"
+
+// ScanIterator is used to incrementally iterate over a collection of elements.
+// It's safe for concurrent use by multiple goroutines.
+type ScanIterator struct {
+	mu  sync.Mutex // protects Scanner and pos
+	cmd *ScanCmd
+	pos int
+}
+
+// Err returns the last iterator error, if any.
+func (it *ScanIterator) Err() error {
+	it.mu.Lock()
+	err := it.cmd.Err()
+	it.mu.Unlock()
+	return err
+}
+
+// Next advances the cursor and returns true if more values can be read.
+func (it *ScanIterator) Next() bool {
+	it.mu.Lock()
+	defer it.mu.Unlock()
+
+	// Instantly return on errors.
+	if it.cmd.Err() != nil {
+		return false
+	}
+
+	// Advance cursor, check if we are still within range.
+	if it.pos < len(it.cmd.page) {
+		it.pos++
+		return true
+	}
+
+	for {
+		// Return if there is no more data to fetch.
+		if it.cmd.cursor == 0 {
+			return false
+		}
+
+		// Fetch next page.
+		if it.cmd._args[0] == "scan" {
+			it.cmd._args[1] = it.cmd.cursor
+		} else {
+			it.cmd._args[2] = it.cmd.cursor
+		}
+
+		err := it.cmd.process(it.cmd)
+		if err != nil {
+			return false
+		}
+
+		it.pos = 1
+
+		// Redis can occasionally return empty page.
+		if len(it.cmd.page) > 0 {
+			return true
+		}
+	}
+}
+
+// Val returns the key/field at the current cursor position.
+func (it *ScanIterator) Val() string {
+	var v string
+	it.mu.Lock()
+	if it.cmd.Err() == nil && it.pos > 0 && it.pos <= len(it.cmd.page) {
+		v = it.cmd.page[it.pos-1]
+	}
+	it.mu.Unlock()
+	return v
+}