Add tests for blocking XREAD[GROUP] when the stream ran dry (#10035)

The purpose of this commit is to add some tests to
cover #5299, which was fixed in #5300 but without tests.

This commit should close #5306 and #5299.

tests/unit/type/stream-cgroups.tcl

@@ -205,11 +205,87 @@ start_server {
         $rd close
     }
 
+    test {Blocking XREADGROUP for stream that ran dry (issue #5299)} {
+        set rd [redis_deferring_client]
+
+        # Add a entry then delete it, now stream's last_id is 666.
+        r DEL mystream
+        r XGROUP CREATE mystream mygroup $ MKSTREAM
+        r XADD mystream 666 key value
+        r XDEL mystream 666
+
+        # Pass a special `>` ID but without new entry, released on timeout.
+        $rd XREADGROUP GROUP mygroup myconsumer BLOCK 10 STREAMS mystream >
+        assert_equal [$rd read] {}
+
+        # Throw an error if the ID equal or smaller than the last_id.
+        assert_error ERR*equal*smaller* {r XADD mystream 665 key value}
+        assert_error ERR*equal*smaller* {r XADD mystream 666 key value}
+
+        # Entered blocking state and then release because of the new entry.
+        $rd XREADGROUP GROUP mygroup myconsumer BLOCK 0 STREAMS mystream >
+        wait_for_blocked_clients_count 1
+        r XADD mystream 667 key value
+        assert_equal [$rd read] {{mystream {{667-0 {key value}}}}}
+
+        $rd close
+    }
+
+    test "Blocking XREADGROUP will ignore BLOCK if ID is not >" {
+        set rd [redis_deferring_client]
+
+        # Add a entry then delete it, now stream's last_id is 666.
+        r DEL mystream
+        r XGROUP CREATE mystream mygroup $ MKSTREAM
+        r XADD mystream 666 key value
+        r XDEL mystream 666
+
+        # Return right away instead of blocking, return the stream with an
+        # empty list instead of NIL if the ID specified is not the special `>` ID.
+        foreach id {0 600 666 700} {
+            $rd XREADGROUP GROUP mygroup myconsumer BLOCK 0 STREAMS mystream $id
+            assert_equal [$rd read] {{mystream {}}}
+        }
+
+        # After adding a new entry, `XREADGROUP BLOCK` still return the stream
+        # with an empty list because the pending list is empty.
+        r XADD mystream 667 key value
+        foreach id {0 600 666 667 700} {
+            $rd XREADGROUP GROUP mygroup myconsumer BLOCK 0 STREAMS mystream $id
+            assert_equal [$rd read] {{mystream {}}}
+        }
+
+        # After we read it once, the pending list is not empty at this time,
+        # pass any ID smaller than 667 will return one of the pending entry.
+        set res [r XREADGROUP GROUP mygroup myconsumer BLOCK 0 STREAMS mystream >]
+        assert_equal $res {{mystream {{667-0 {key value}}}}}
+        foreach id {0 600 666} {
+            $rd XREADGROUP GROUP mygroup myconsumer BLOCK 0 STREAMS mystream $id
+            assert_equal [$rd read] {{mystream {{667-0 {key value}}}}}
+        }
+
+        # Pass ID equal or greater than 667 will return the stream with an empty list.
+        foreach id {667 700} {
+            $rd XREADGROUP GROUP mygroup myconsumer BLOCK 0 STREAMS mystream $id
+            assert_equal [$rd read] {{mystream {}}}
+        }
+
+        # After we ACK the pending entry, return the stream with an empty list.
+        r XACK mystream mygroup 667
+        foreach id {0 600 666 667 700} {
+            $rd XREADGROUP GROUP mygroup myconsumer BLOCK 0 STREAMS mystream $id
+            assert_equal [$rd read] {{mystream {}}}
+        }
+
+        $rd close
+    }
+
     test {XGROUP DESTROY should unblock XREADGROUP with -NOGROUP} {
         r del mystream
         r XGROUP CREATE mystream mygroup $ MKSTREAM
         set rd [redis_deferring_client]
-        $rd XREADGROUP GROUP mygroup Alice BLOCK 100 STREAMS mystream ">"
+        $rd XREADGROUP GROUP mygroup Alice BLOCK 0 STREAMS mystream ">"
+        wait_for_blocked_clients_count 1
         r XGROUP DESTROY mystream mygroup
         assert_error "*NOGROUP*" {$rd read}
         $rd close
@@ -220,6 +296,7 @@ start_server {
         r XGROUP CREATE mystream{t} mygroup $ MKSTREAM
         set rd [redis_deferring_client]
         $rd XREADGROUP GROUP mygroup Alice BLOCK 0 STREAMS mystream{t} ">"
+        wait_for_blocked_clients_count 1
         r XGROUP CREATE mystream2{t} mygroup $ MKSTREAM
         r XADD mystream2{t} 100 f1 v1
         r RENAME mystream2{t} mystream{t}
@@ -232,6 +309,7 @@ start_server {
         r XGROUP CREATE mystream{t} mygroup $ MKSTREAM
         set rd [redis_deferring_client]
         $rd XREADGROUP GROUP mygroup Alice BLOCK 0 STREAMS mystream{t} ">"
+        wait_for_blocked_clients_count 1
         r XADD mystream2{t} 100 f1 v1
         r RENAME mystream2{t} mystream{t}
         assert_error "*NOGROUP*" {$rd read} ;# mystream2{t} didn't have mygroup before RENAME
@@ -560,6 +638,7 @@ start_server {
             r XREADGROUP GROUP mygroup Alice NOACK STREAMS mystream ">"
             set rd [redis_deferring_client]
             $rd XREADGROUP GROUP mygroup Bob BLOCK 0 NOACK STREAMS mystream ">"
+            wait_for_blocked_clients_count 1
             r XADD mystream * f2 v2
             set grpinfo [r xinfo groups mystream]
 
@@ -580,6 +659,7 @@ start_server {
             r XREADGROUP GROUP mygroup Alice NOACK STREAMS mystream ">"
             set rd [redis_deferring_client]
             $rd XREADGROUP GROUP mygroup Bob BLOCK 0 NOACK STREAMS mystream ">"
+            wait_for_blocked_clients_count 1
             r XGROUP CREATECONSUMER mystream mygroup Charlie
             set grpinfo [lindex [r xinfo groups mystream] 0]
 

tests/unit/type/stream.tcl

@@ -354,6 +354,31 @@ start_server {
         $rd close
     }
 
+    test "Blocking XREAD for stream that ran dry (issue #5299)" {
+        set rd [redis_deferring_client]
+
+        # Add a entry then delete it, now stream's last_id is 666.
+        r DEL mystream
+        r XADD mystream 666 key value
+        r XDEL mystream 666
+
+        # Pass a ID smaller than stream's last_id, released on timeout.
+        $rd XREAD BLOCK 10 STREAMS mystream 665
+        assert_equal [$rd read] {}
+
+        # Throw an error if the ID equal or smaller than the last_id.
+        assert_error ERR*equal*smaller* {r XADD mystream 665 key value}
+        assert_error ERR*equal*smaller* {r XADD mystream 666 key value}
+
+        # Entered blocking state and then release because of the new entry.
+        $rd XREAD BLOCK 0 STREAMS mystream 665
+        wait_for_blocked_clients_count 1
+        r XADD mystream 667 key value
+        assert_equal [$rd read] {{mystream {{667-0 {key value}}}}}
+
+        $rd close
+    }
+
     test "XREAD: XADD + DEL should not awake client" {
         set rd [redis_deferring_client]
         r del s1