Added BITFIELD_RO variants for read-only operations.

src/bitops.c

@@ -902,6 +902,9 @@ void bitposCommand(client *c) {
  * OVERFLOW [WRAP|SAT|FAIL]
  */
 
+#define BITFIELD_COMMON (1<<0)
+#define BITFIELD_READONLY (1<<1)
+
 struct bitfieldOp {
     uint64_t offset;    /* Bitfield offset. */
     int64_t i64;        /* Increment amount (INCRBY) or SET value */
@@ -911,7 +914,7 @@ struct bitfieldOp {
     int sign;           /* True if signed, otherwise unsigned op. */
 };
 
-void bitfieldCommand(client *c) {
+void bitfieldGeneric(client *c, int flags) {
     robj *o;
     size_t bitoffset;
     int j, numops = 0, changes = 0;
@@ -999,6 +1002,12 @@ void bitfieldCommand(client *c) {
             return;
         }
     } else {
+        if (flags & BITFIELD_READONLY) {
+            zfree(ops);
+            addReplyError(c, "bitfield_ro only support get subcommand");
+            return;
+        }
+
         /* Lookup by making room up to the farest bit reached by
          * this operation. */
         if ((o = lookupStringForBitCommand(c,
@@ -1129,3 +1138,11 @@ void bitfieldCommand(client *c) {
     }
     zfree(ops);
 }
+
+void bitfieldCommand(client *c) {
+    bitfieldGeneric(c, BITFIELD_COMMON);
+}
+
+void bitfieldroCommand(client *c) {
+    bitfieldGeneric(c, BITFIELD_READONLY);
+}

src/server.c

@@ -238,6 +238,10 @@ struct redisCommand redisCommandTable[] = {
      "write use-memory @bitmap",
      0,NULL,1,1,1,0,0,0},
 
+    {"bitfield_ro",bitfieldroCommand,-2,
+     "read-only fast @bitmap",
+     0,NULL,1,1,1,0,0,0},
+
     {"setrange",setrangeCommand,4,
      "write use-memory @string",
      0,NULL,1,1,1,0,0,0},

src/server.h

@@ -2177,6 +2177,7 @@ void existsCommand(client *c);
 void setbitCommand(client *c);
 void getbitCommand(client *c);
 void bitfieldCommand(client *c);
+void bitfieldroCommand(client *c);
 void setrangeCommand(client *c);
 void getrangeCommand(client *c);
 void incrCommand(client *c);

tests/unit/bitfield.tcl

@@ -199,3 +199,34 @@ start_server {tags {"bitops"}} {
         r del mystring
     }
 }
+
+start_server {tags {"repl"}} {
+    start_server {} {
+        set master [srv -1 client]
+        set master_host [srv -1 host]
+        set master_port [srv -1 port]
+        set slave [srv 0 client]
+
+        test {setup slave} {
+            $slave slaveof $master_host $master_port
+            wait_for_condition 50 100 {
+                [s 0 master_link_status] eq {up}
+            } else {
+                fail "Replication not started."
+            }
+        }
+
+        test {write on master, read on slave} {
+            $master del bits
+            assert_equal 0 [$master bitfield bits set u8 0 255]
+            assert_equal 255 [$master bitfield bits set u8 0 100]
+            wait_for_ofs_sync $master $slave
+            assert_equal 100 [$slave bitfield_ro bits get u8 0]
+        }
+
+        test {bitfield_ro with write option} {
+            catch {$slave bitfield_ro bits set u8 0 100 get u8 0} err
+            assert_match {*ERR bitfield_ro only support get subcommand*} $err
+        }
+    }
+}