redis-cli - add option --count for scan (#12042)

When using scan in redis-cli, the SCAN COUNT is fixed, which means the
full scan can take a long time if there are a lot of keys, this will let users specify
a bigger COUNT option.

src/redis-cli.c

@@ -239,6 +239,7 @@ static struct config {
     int get_functions_rdb_mode;
     int stat_mode;
     int scan_mode;
+    int count;
     int intrinsic_latency_mode;
     int intrinsic_latency_duration;
     sds pattern;
@@ -2727,6 +2728,8 @@ static int parseOptions(int argc, char **argv) {
         } else if (!strcmp(argv[i],"--pattern") && !lastarg) {
             sdsfree(config.pattern);
             config.pattern = sdsnew(argv[++i]);
+        } else if (!strcmp(argv[i],"--count") && !lastarg) {
+            config.count = atoi(argv[++i]);
         } else if (!strcmp(argv[i],"--quoted-pattern") && !lastarg) {
             sdsfree(config.pattern);
             config.pattern = unquoteCString(argv[++i]);
@@ -3081,6 +3084,7 @@ version,tls_usage);
 "  --scan             List all keys using the SCAN command.\n"
 "  --pattern <pat>    Keys pattern when using the --scan, --bigkeys or --hotkeys\n"
 "                     options (default: *).\n"
+"  --count <count>    Count option when using the --scan, --bigkeys or --hotkeys (default: 10).\n"
 "  --quoted-pattern <pat> Same as --pattern, but the specified string can be\n"
 "                         quoted, in order to pass an otherwise non binary-safe string.\n"
 "  --intrinsic-latency <sec> Run a test to measure intrinsic system latency.\n"
@@ -3111,6 +3115,7 @@ version,tls_usage);
 "  redis-cli --quoted-input set '\"null-\\x00-separated\"' value\n"
 "  redis-cli --eval myscript.lua key1 key2 , arg1 arg2 arg3\n"
 "  redis-cli --scan --pattern '*:12345*'\n"
+"  redis-cli --scan --pattern '*:12345*' --count 100\n"
 "\n"
 "  (Note: when using --eval the comma separates KEYS[] from ARGV[] items)\n"
 "\n"
@@ -8826,8 +8831,8 @@ static redisReply *sendScan(unsigned long long *it) {
     redisReply *reply;
 
     if (config.pattern)
-        reply = redisCommand(context, "SCAN %llu MATCH %b",
-            *it, config.pattern, sdslen(config.pattern));
+        reply = redisCommand(context, "SCAN %llu MATCH %b COUNT %d",
+            *it, config.pattern, sdslen(config.pattern), config.count);
     else
         reply = redisCommand(context,"SCAN %llu",*it);
 
@@ -9770,6 +9775,7 @@ int main(int argc, char **argv) {
     config.get_functions_rdb_mode = 0;
     config.stat_mode = 0;
     config.scan_mode = 0;
+    config.count = 10;
     config.intrinsic_latency_mode = 0;
     config.pattern = NULL;
     config.rdb_filename = NULL;