Add Redis source code for testing

1 files changed, 910 insertions, 0 deletions

diff --git a/examples/redis-unstable/tests/unit/moduleapi/keymeta.tcl b/examples/redis-unstable/tests/unit/moduleapi/keymeta.tcl
new file mode 100644
index 0000000..ebb7784
--- /dev/null
+++ b/examples/redis-unstable/tests/unit/moduleapi/keymeta.tcl
@@ -0,0 +1,910 @@
+# ============================================================================
+# Key Metadata (keymeta) Test Suite
+# ============================================================================
+#
+# Tests the Redis module key metadata framework: up to 7 independent metadata
+# classes (IDs 1-7) can be attached to keys. Class ID 0 is reserved for key
+# expiration.
+#
+# The following features are sensitive to Key Metadata and are tested here:
+#
+# - KEY EXPIRATION (class ID 0)
+#   - Stored at ((uint64_t *)kv) - 1 (first metadata slot)
+#   - Managed via db->expires dictionary
+#   - Must be preserved/updated when kvobj is reallocated
+# - HASH FIELD EXPIRATION (HFE)
+#   - NOT in kvobj metadata slots (Maybe in the future...)
+#   - Managed via db->hexpires ebuckets (holds direct kvobj pointer)
+#   - Must be removed before kvobj reallocation (hashTypeRemoveFromExpires)
+#      and restored after (hashTypeAddToExpires)
+# - MODULE METADATA (class IDs 1-7)
+#   - Defines metadata lifecycle via callbacks
+# - EMBEDDED STRINGS vs. REGULAR OBJECTS
+#   - Short strings and numbers are embedded into kvobj
+#   - The rest are kept as distinct objects
+# - LAZYFREE
+# ============================================================================
+
+set testmodule [file normalize tests/modules/test_keymeta.so]
+
+# Helper procedure to convert class ID to 4-char-id name
+proc cname {cid} {
+    return "KMT$cid"
+}
+
+# Helper procedure to check if a class should keep metadata for a given operation
+proc shouldKeep {cid operation classesSpec} {
+    upvar $classesSpec specs
+    set spec $specs($cid)
+    switch $operation {
+        "copy"   { return [string match "*KEEPONCOPY*" $spec] }
+        "rename" { return [string match "*KEEPONRENAME*" $spec] }
+        "move"   { return [string match "*KEEPONMOVE*" $spec] }
+        default  { return 0 }
+    }
+}
+
+# Helper procedure to setup a key with metadata
+proc setupKeyMeta {keyname numClasses expiryBefore expiryAfter} {
+    # Set expiry if requested
+    if {$expiryBefore} {
+        r expire $keyname 10000
+        assert_range [r ttl $keyname] 9990 10000
+    }
+
+    # Set metadata for all classes
+    for {set i 1} {$i <= $numClasses} {incr i} {
+        # Set twice to verify overwrite behavior
+        r keymeta.set [cname $i] $keyname "blabla$i"
+        assert_equal [r keymeta.get [cname $i] $keyname] "blabla$i"
+        r keymeta.set [cname $i] $keyname "meta$i"
+    }
+
+    # Verify metadata was set correctly
+    for {set i 1} {$i <= $numClasses} {incr i} {
+        assert_equal [r keymeta.get [cname $i] $keyname] "meta$i"
+    }
+
+    if {$expiryAfter} {
+        r expire $keyname 10000
+        assert_range [r ttl $keyname] 9990 10000
+    }
+
+    if {$expiryBefore} {
+        assert_range [r ttl $keyname] 9990 10000
+    }
+}
+
+# Helper procedure to verify metadata after an operation
+proc verifyKeyMeta {keyname operation numClasses hasExpiry classesSpec} {
+    upvar $classesSpec specs
+
+    # Verify expiry
+    if {$hasExpiry} {
+        assert_range [r ttl $keyname] 9990 10000
+    }
+
+    # Verify metadata based on class spec
+    for {set i 1} {$i <= $numClasses} {incr i} {
+        set expected [expr {[shouldKeep $i $operation specs] ? "meta$i" : ""}]
+        assert_equal [r keymeta.get [cname $i] $keyname] $expected
+    }
+}
+
+proc flushallAndVerifyCleanup {} {
+    r flushall
+    # Verify all metadata is cleaned up properly
+    assert_equal [r keymeta.active] 0
+}
+
+start_server {tags {"modules" "external:skip" "cluster:skip"} overrides {enable-debug-command yes}} {
+    r module load $testmodule
+
+    array set classesSpec {}
+    set classesSpec(1) "KEEPONCOPY:KEEPONRENAME:KEEPONMOVE:ALLOWIGNORE:RDBLOAD:RDBSAVE"
+    set classesSpec(2) "KEEPONCOPY:KEEPONRENAME:UNLINKFREE:ALLOWIGNORE:RDBLOAD:RDBSAVE"
+    set classesSpec(3) "KEEPONCOPY:ALLOWIGNORE:RDBLOAD:RDBSAVE"
+    set classesSpec(4) "ALLOWIGNORE:RDBLOAD:RDBSAVE"
+    set classesSpec(5) "KEEPONRENAME:KEEPONMOVE:ALLOWIGNORE:RDBLOAD:RDBSAVE"
+    set classesSpec(6) "KEEPONRENAME:ALLOWIGNORE:RDBLOAD:RDBSAVE"
+    set classesSpec(7) "KEEPONMOVE:UNLINKFREE:ALLOWIGNORE:RDBLOAD:RDBSAVE"
+
+    array set classes {}
+    for {set cid 1} {$cid <= 7} {incr cid} {
+        set spec $classesSpec($cid)
+        set classes($cid) [r keymeta.register [cname $cid] 1 $spec]
+        puts "Registered class $cid with spec $spec"
+        assert_equal $classes($cid) $cid
+    }
+
+    # Validates metadata behavior across COPY/RENAME/MOVE operations
+    # with varying numbers of metadata classes (1-7), key expiration states,
+    # key types (string/hash), hash field expiration, and metadata class flags
+    # (KEEPONCOPY, KEEPONRENAME, KEEPONMOVE).
+    for {set numClasses 1} {$numClasses < 8} {incr numClasses} {
+        foreach expiryBefore {0 1} {
+            foreach expiryAfter {0 1} {
+                set hasExpiry [expr {$expiryBefore || $expiryAfter}]
+                set expiryStr "expiryBefore=$expiryBefore, expiryAfter=$expiryAfter)"
+                # Test COPY operation
+                test "KEYMETA - copy key-string with $numClasses classes, $expiryStr" {
+                    foreach value { 3 "value1" [string repeat "ABCD" 1000]} {
+                        r select 0
+                        r del k1 k2
+                        r set k1 $value
+                        setupKeyMeta k1 $numClasses $expiryBefore $expiryAfter
+                        # Copy:
+                        r copy k1 k2
+                        # Verify:
+                        assert_equal [r get k1] $value
+                        assert_equal [r get k2] $value
+                        # Verify expiry and metadata
+                        verifyKeyMeta k2 "copy" $numClasses $hasExpiry classesSpec
+                        flushallAndVerifyCleanup
+                    }
+                }
+
+                test "KEYMETA - copy key-hash with $numClasses classes, $expiryStr" {
+                    r select 0
+                    r del h1 h2
+                    r HSET h1 field1 "value1" field2 "value2"
+                    r hexpire h1 10000 FIELDS 1 field1
+                    setupKeyMeta h1 $numClasses $expiryBefore $expiryAfter
+                    # Copy:
+                    r copy h1 h2
+                    # Verify:
+                    verifyKeyMeta h2 "copy" $numClasses $hasExpiry classesSpec
+                    assert_range [r httl h1 FIELDS 1 field1] 9999 10000
+                    assert_range [r httl h2 FIELDS 1 field1] 9999 10000
+                    flushallAndVerifyCleanup
+                }
+
+                # Test RENAME operation
+                test "KEYMETA - rename key-string with $numClasses classes, $expiryStr" {
+                    foreach value { 3 "value1" [string repeat "ABCD" 1000]} {
+                        r select 0
+                        r del k1 k2
+                        r set k1 $value
+                        setupKeyMeta k1 $numClasses $expiryBefore $expiryAfter
+                        # Rename:
+                        r rename k1 k2
+                        # Verify:
+                        assert_equal [r exists k1] 0
+                        assert_equal [r get k2] $value
+                        # Verify expiry and metadata
+                        verifyKeyMeta k2 "rename" $numClasses $hasExpiry classesSpec
+                        flushallAndVerifyCleanup
+                    }
+                }
+
+                test "KEYMETA - rename key-hash with $numClasses classes, $expiryStr" {
+                    r select 0
+                    r del h1 h2
+                    r HSET h1 field1 "value1" field2 "value2"
+                    r hexpire h1 10000 FIELDS 1 field1
+                    setupKeyMeta h1 $numClasses $expiryBefore $expiryAfter
+                    # Rename:
+                    r rename h1 h2
+                    # Verify:
+                    assert_equal [r exists h1] 0
+                    assert_range [r httl h2 FIELDS 1 field1] 9999 10000
+                    verifyKeyMeta h2 "rename" $numClasses $hasExpiry classesSpec
+                    flushallAndVerifyCleanup
+                }
+
+
+
+                # Test MOVE operation
+                test "KEYMETA - move key-string with $numClasses classes, $expiryStr" {
+                    foreach value { 3 "value1" [string repeat "ABCD" 1000]} {
+                        r select 9
+                        r del k1
+                        r select 0
+                        r del k1
+                        r set k1 $value
+                        setupKeyMeta k1 $numClasses $expiryBefore $expiryAfter
+                        # Perform move
+                        assert_equal [r move k1 9] 1
+                        # Verify key moved
+                        assert_equal [r exists k1] 0
+                        r select 9
+                        assert_equal [r get k1] $value
+                        # Verify expiry and metadata
+                        verifyKeyMeta k1 "move" $numClasses $hasExpiry classesSpec
+                        r select 0
+                        flushallAndVerifyCleanup
+                    }
+                }
+
+                test "KEYMETA - move key-hash with $numClasses classes, $expiryStr" {
+                    r select 9
+                    r del h1
+                    r select 0
+                    r del h1
+                    r HSET h1 field1 "value1" field2 "value2"
+                    r hexpire h1 10000 FIELDS 1 field1
+                    setupKeyMeta h1 $numClasses $expiryBefore $expiryAfter
+                    assert_range [r httl h1 FIELDS 1 field1] 9999 10000
+                    assert_equal [r move h1 9] 1
+                    assert_equal [r exists h1] 0
+                    r select 9
+                    assert_range [r httl h1 FIELDS 1 field1] 9999 10000
+                    verifyKeyMeta h1 "move" $numClasses $hasExpiry classesSpec
+                    r select 0
+                    flushallAndVerifyCleanup
+                }
+            }
+        }
+    }
+
+    test "KEYMETA - Verify active metadata count on copy" {
+        for {set cid 1} {$cid < 7} {incr cid} {
+            set numAlloc 0
+            flushallAndVerifyCleanup
+            set dupOnCopy [shouldKeep $cid "copy" classesSpec]
+            r set k1 "v1"
+            r keymeta.set [cname $cid] k1 "meta1"
+            assert_equal [r keymeta.active] [incr numAlloc]
+            r keymeta.set [cname $cid] k1 "meta1b"
+            assert_equal [r keymeta.active] $numAlloc
+            r copy k1 k1copy
+            assert_equal [r keymeta.active] [incr numAlloc $dupOnCopy]
+            r del k1
+            assert_equal [r keymeta.active] [incr numAlloc -1]
+            r del k1copy
+            assert_equal [r keymeta.active] 0
+        }
+    }
+
+    test "KEYMETA - Verify active metadata count on rename" {
+        for {set cid 1} {$cid <= 7} {incr cid} {
+            set numAlloc 0
+            flushallAndVerifyCleanup
+            set keepOnRename [shouldKeep $cid "rename" classesSpec]
+            set discOnRename [expr {!$keepOnRename}]
+            r set k1 "v1"
+            r keymeta.set [cname $cid] k1 "meta1"
+            assert_equal [r keymeta.active] [incr numAlloc]
+            r rename k1 k1_renamed
+            assert_equal [r keymeta.active] [incr numAlloc -$discOnRename]
+            r del k1_renamed
+            assert_equal [r keymeta.active] 0
+        }
+    }
+
+    test "KEYMETA - Verify active metadata count on move" {
+        for {set cid 1} {$cid <= 7} {incr cid} {
+            set numAlloc 0
+            r select 0
+            flushallAndVerifyCleanup
+
+            set keepOnMove [shouldKeep $cid "move" classesSpec]
+            set discOnMove [expr {!$keepOnMove}]
+
+            # Create keys with metadata in DB 0
+            r set k1 "v1"
+            r keymeta.set [cname $cid] k1 "meta1"
+            assert_equal [r keymeta.active] [incr numAlloc]
+            # Move: metadata discarded if !keepOnMove
+            r move k1 9
+            set active [r keymeta.active]
+            assert_equal [r keymeta.active] [incr numAlloc -$discOnMove]
+            # Cleanup
+            r select 9
+            r del k1
+            r select 0
+            assert_equal [r keymeta.active] 0
+        }
+    }
+
+    test "KEYMETA - Verify metadta cleanup on lazyfree" {
+        r config set lazyfree-lazy-user-del yes
+        # Class 2 has UNLINKFREE flag, so it should call unlink callback when lazyfree is enabled
+        # Class 1 does not have UNLINKFREE flag, so it should only call free callback
+        foreach {cid} { 1 2 } {
+            r config resetstat
+            # Create a large unsorted set collection to ensure it exceeds LAZYFREE_THRESHOLD
+            for {set i 0} {$i < 1024} {incr i} { r sadd myset $i }
+            r keymeta.set [cname $cid] myset "meta"
+            assert_equal [r keymeta.active] 1
+            r del myset
+
+            # Wait for lazyfree to complete and verify lazyfreed_objects incremented
+            wait_for_condition 50 100 {
+                [s lazyfree_pending_objects] == 0
+            } else {
+                fail "lazyfree isn't done"
+            }
+            assert_equal [r keymeta.active] 0
+            assert_equal [s lazyfreed_objects] 1
+        }
+        r config set lazyfree-lazy-user-del no
+    } {OK} {needs:config-resetstat}
+
+    test "KEYMETA - Verify metadata cleanup on expire" {
+        # Class 2 has UNLINKFREE flag, so it should call unlink callback when lazyfree is enabled
+        # Class 1 does not have UNLINKFREE flag, so it should only call free callback
+        foreach {cid} { 1 2 } {
+            r set mykey "mykey$cid"
+            r keymeta.set [cname $cid] mykey "meta"
+            assert_equal [r keymeta.active] 1
+            r pexpire mykey 1
+            wait_for_condition 50 100 {
+                [r exists mykey] == 0
+            } else {
+                fail "key not expired"
+            }
+            assert_equal [r keymeta.active] 0
+        }
+    }
+
+    # ============================================================================
+    # AOF Rewrite Tests
+    # ============================================================================
+    # Note: Full AOF round-trip tests (write → restart → load) are not included
+    # because the test module registers classes dynamically via commands, which
+    # creates a chicken-and-egg problem:
+    # - Classes must be registered BEFORE AOF loading (in RedisModule_OnLoad)
+    # - But the KEYMETA.REGISTER commands are in the AOF itself
+    # - When server restarts and loads AOF, classes aren't registered yet
+    # - KEYMETA.SET commands fail with "metadata class not found"
+    #
+    # For production modules, classes MUST be registered in RedisModule_OnLoad()
+    # to ensure they're available when AOF/RDB files are loaded on server startup.
+    # See src/module.c documentation for RM_CreateKeyMetaClass() for details.
+    #
+    # The test below verifies that AOF callbacks correctly emit KEYMETA.SET commands
+    # to the AOF file during rewrite, which is the module's responsibility.
+    test "KEYMETA - AOF rewrite emits correct KEYMETA.SET commands to file" {
+        # This test verifies that the AOF callback implementation correctly writes
+        # KEYMETA.SET commands to the AOF file during rewrite. We don't test the
+        # full round-trip (restart + load) due to the dynamic registration limitation
+        # explained above.
+
+        r config set appendonly yes
+        r config set auto-aof-rewrite-percentage 0
+        r config set aof-use-rdb-preamble no
+        # Wait for the initial AOF rewrite that Redis triggers when enabling AOF
+        waitForBgrewriteaof r
+
+        # Create keys with metadata from multiple classes
+        r set key1 "value1"
+        r keymeta.set [cname 1] key1 "metadata_c1"
+
+        r set key2 "value2"
+        r keymeta.set [cname 2] key2 "metadata_c2"
+        r keymeta.set [cname 3] key2 "metadata_c3"
+
+        r hset hashkey field1 val1
+        r keymeta.set [cname 4] hashkey "hash_meta"
+
+        # Trigger AOF rewrite
+        r bgrewriteaof
+        waitForBgrewriteaof r
+
+        # Get the AOF directory and read the AOF file
+        set aof_dir [lindex [r config get dir] 1]
+        set aof_base_filename [lindex [r config get appendfilename] 1]
+
+        # Find the base AOF file (after rewrite)
+        set aof_files [glob -nocomplain -directory $aof_dir appendonlydir/${aof_base_filename}.*.base.aof]
+        assert {[llength $aof_files] > 0}
+
+        # Read the most recent base AOF file
+        set aof_file [lindex [lsort $aof_files] end]
+        set fp [open $aof_file r]
+        set aof_content [read $fp]
+        close $fp
+
+        # Verify the AOF contains KEYMETA.SET commands with correct format
+        assert_match "*KEYMETA.SET*[cname 1]*key1*metadata_c1*" $aof_content
+        assert_match "*KEYMETA.SET*[cname 2]*key2*metadata_c2*" $aof_content
+        assert_match "*KEYMETA.SET*[cname 3]*key2*metadata_c3*" $aof_content
+        assert_match "*KEYMETA.SET*[cname 4]*hashkey*hash_meta*" $aof_content
+
+        # Verify the RESP format is correct by checking for the command structure
+        # The AOF should contain: *4 (array of 4 elements)
+        assert_match "*\$11*KEYMETA.SET*" $aof_content
+        # Count how many KEYMETA.SET commands are in the AOF
+        set keymeta_count [regexp -all {KEYMETA\.SET} $aof_content]
+        assert_equal $keymeta_count 4
+    } {} {external:skip}
+
+    # ========================================================================
+    # RDB Save/Load Tests
+    # ========================================================================
+
+    test {RDB: SAVE and reload preserves metadata} {
+        # Create key with metadata
+        r set key1 "value1"
+        r keymeta.set [cname 1] key1 "key1_meta1"
+        assert_equal [r keymeta.get [cname 1] key1] "key1_meta1"
+
+        r save
+        r debug reload
+
+        # Verify metadata persisted after reload
+        assert_equal [r keymeta.get [cname 1] key1] "key1_meta1"
+
+        flushallAndVerifyCleanup
+    } {} {external:skip needs:save}
+
+    test {RDB: BGSAVE writes metadata to RDB file} {
+        # Create keys with different metadata combinations
+        r set key1 "value1"
+        r keymeta.set [cname 1] key1 "key1_meta1"
+
+        r set key2 "value2"
+        r keymeta.set [cname 1] key2 "key2_meta1"
+        r keymeta.set [cname 2] key2 "key2_meta2"
+
+        # Trigger BGSAVE and reload (debug reload preserves modules)
+        r bgsave
+        waitForBgsave r
+        r debug reload
+
+        # Verify metadata persisted after reload
+        assert_equal [r keymeta.get [cname 1] key1] "key1_meta1"
+        assert_equal [r keymeta.get [cname 1] key2] "key2_meta1"
+        assert_equal [r keymeta.get [cname 2] key2] "key2_meta2"
+
+        flushallAndVerifyCleanup
+    } {} {external:skip needs:save}
+
+    test {RDB: Metadata persists with expiretime} {
+        # Create key with both expiry and metadata
+        r set key1 "value1"
+        set expire_time [expr {[clock seconds] + 10000}]
+        r expireat key1 $expire_time
+        r keymeta.set [cname 1] key1 "meta_with_expire"
+
+        assert_equal [r expiretime key1] $expire_time
+        assert_equal [r keymeta.get [cname 1] key1] "meta_with_expire"
+
+        # Reload from RDB
+        r debug reload
+
+        # Verify metadata and expiry persist after reload
+        assert_equal [r expiretime key1] $expire_time
+        assert_equal [r keymeta.get [cname 1] key1] "meta_with_expire"
+
+        flushallAndVerifyCleanup
+    } {} {external:skip needs:debug}
+
+    test {RDB: Create keys with upto 7 meta classes, with or without expiry} {
+        # Test all combinations of 1-7 metadata classes, with or without expiry
+        for {set n 1} {$n <= 7} {incr n} {
+            foreach hasExpiry {0 1} {
+                set keyname "key_${n}_exp${hasExpiry}"
+                r set $keyname "value$n"
+
+                # Set expiry if hasExpiry is 1
+                if {$hasExpiry} {
+                    set ttl [expr {3600 + $n}]
+                    r expire $keyname $ttl
+                    # Get the actual expiretime set by Redis to use as expected value
+                    set expExpiry [r expiretime $keyname]
+                }
+
+                # Create list of class IDs to attach (1 through n)
+                set class_ids {}
+                for {set i 1} {$i <= $n} {incr i} {
+                    lappend class_ids $i
+                }
+
+                # Randomize the order of metadata attachment
+                set class_ids [lshuffle $class_ids]
+
+                # Attach metadata in randomized order
+                foreach cid $class_ids {
+                    r keymeta.set [cname $cid] $keyname "meta$cid"
+                }
+
+                # Verify metadata before RDB save
+                # Verify exactly n metadata classes are attached
+                for {set i 1} {$i <= 7} {incr i} {
+                    if {$i <= $n} {
+                        assert_equal [r keymeta.get [cname $i] $keyname] "meta$i"
+                    } else {
+                        assert_equal [r keymeta.get [cname $i] $keyname] ""
+                    }
+                }
+
+                # Verify expiry before RDB save
+                if {$hasExpiry} {
+                    set actual_expiretime [r expiretime $keyname]
+                    assert_equal $actual_expiretime $expExpiry
+                }
+
+                # Save and reload from RDB (debug reload preserves modules)
+                r save
+                r debug reload
+
+                # Verify metadata after RDB reload
+                # Verify exactly n metadata classes are still attached
+                for {set i 1} {$i <= 7} {incr i} {
+                    if {$i <= $n} {
+                        assert_equal [r keymeta.get [cname $i] $keyname] "meta$i"
+                    } else {
+                        assert_equal [r keymeta.get [cname $i] $keyname] ""
+                    }
+                }
+
+                # Verify expiry after RDB reload
+                if {$hasExpiry} {
+                    set actual_expiretime [r expiretime $keyname]
+                    assert_equal $actual_expiretime $expExpiry
+                } else {
+                    # Verify no expiry set
+                    assert_equal [r expiretime $keyname] -1
+                }
+                flushallAndVerifyCleanup
+            }
+        }
+    } {} {external:skip needs:save}
+
+    # ========================================================================
+    # RDB Flag Tests: ALLOW_IGNORE, RDBLOAD, RDBSAVE
+    # ========================================================================
+
+    # Test all combinations except the error case (ALLOW_IGNORE=0, RDBLOAD=0, RDBSAVE=1)
+    foreach RDBLOAD {0 1} {
+        foreach RDBSAVE {0 1} {
+            foreach ALLOW_IGNORE {0 1} {
+                # Skip the error case - we'll test it last since it causes RDB load to fail
+                if {!$RDBLOAD && $RDBSAVE && !$ALLOW_IGNORE} { continue }
+
+                test "RDB: SAVE and LOAD (ALLOW_IGNORE=$ALLOW_IGNORE, RDBLOAD=$RDBLOAD, RDBSAVE=$RDBSAVE)" {
+                    # Flush all data and save empty RDB to start with a clean slate
+                    r flushall
+                    r save
+
+                    # re-register class 1 with new flags. Expected re-registered same class ID
+                    r keymeta.unregister [cname 1]
+                    # dummy default spec
+                    set newSpec "KEEPONCOPY"
+                    if {$ALLOW_IGNORE} { append newSpec ":ALLOWIGNORE" }
+                    if {$RDBLOAD} { append newSpec ":RDBLOAD" }
+                    if {$RDBSAVE} { append newSpec ":RDBSAVE" }
+
+                    # Must reuse same class-id that it had before
+                    assert_equal $classes(1) [r keymeta.register [cname 1] 1 $newSpec]
+
+                    r set key1 "value1"
+                    r keymeta.set [cname 1] key1 "key1_meta1"
+                    assert_equal [r keymeta.get [cname 1] key1] "key1_meta1"
+
+                    r save
+                    r debug reload
+
+                    # Metadata is preserved only when BOTH rdb_save AND rdb_load are enabled
+                    # Otherwise metadata is lost (either not saved, or saved but not loaded)
+                    set metaPreserved [expr {$RDBSAVE && $RDBLOAD}]
+                    set expectedMeta [expr {$metaPreserved ? "key1_meta1" : ""}]
+
+                    assert_equal [r keymeta.get [cname 1] key1] $expectedMeta
+
+                    flushallAndVerifyCleanup
+                } {} {external:skip needs:save}
+            }
+        }
+    }
+
+    # Test the error case last (ALLOW_IGNORE=0, RDBLOAD=0, RDBSAVE=1)
+    # This test causes RDB load to fail, so we test it last to avoid polluting subsequent tests
+    test "RDB: SAVE and LOAD Invalid combination: (ALLOW_IGNORE=0, RDBLOAD=0, RDBSAVE=1)" {
+        # re-register class 1 with RDBSAVE flag but no RDBLOAD or ALLOW_IGNORE
+        r keymeta.unregister [cname 1]
+        set newSpec "KEEPONCOPY:RDBSAVE"
+        assert_equal $classes(1) [r keymeta.register [cname 1] 1 $newSpec]
+
+        r set key1 "value1"
+        r keymeta.set [cname 1] key1 "key1_meta1"
+        assert_equal [r keymeta.get [cname 1] key1] "key1_meta1"
+
+        r save
+
+        # This combination causes RDB load to fail because:
+        # - Metadata was saved (RDBSAVE=1)
+        # - Class has no rdb_load callback (RDBLOAD=0)
+        # - Errors are not ignored (ALLOW_IGNORE=0)
+        catch {r debug reload} err
+        assert_match "*Error trying to load the RDB dump*" $err
+    } {} {external:skip needs:save}
+
+    # ========================================================================
+    # DUMP/RESTORE Tests
+    # ========================================================================
+
+    test {DUMP/RESTORE: 1 to 7 metadata classes, optional TTL} {
+        foreach withTTL {0 1} {
+            for {set numClasses 1} {$numClasses < 8} {incr numClasses} {
+                # Re-register classes with RDBLOAD and RDBSAVE flags
+                for {set cid 1} {$cid <= $numClasses} {incr cid} {
+                    r keymeta.unregister [cname $cid]
+                    assert_equal $classes($cid) [r keymeta.register [cname $cid] 1 $classesSpec($cid)]
+                }
+
+                # Create key with metadata classes
+                r set key1 "value1"
+                for {set i 1} {$i <= $numClasses} {incr i} {
+                    r keymeta.set [cname $i] key1 "meta${i}_value"
+                }
+
+                if {$withTTL} { r expire key1 10000 }
+
+                # Verify all metadata before DUMP
+                for {set i 1} {$i <= $numClasses} {incr i} {
+                    assert_equal [r keymeta.get [cname $i] key1] "meta${i}_value"
+                }
+
+                # DUMP the key
+                set encoded [r dump key1]
+
+                # Delete and RESTORE
+                r del key1
+                r restore key1 [expr {$withTTL ? 10000 : 0}] $encoded
+
+                # Verify all metadata was restored
+                assert_equal [r get key1] "value1"
+                for {set i 1} {$i <= $numClasses} {incr i} {
+                    assert_equal [r keymeta.get [cname $i] key1] "meta${i}_value"
+                }
+                if {$withTTL} { assert_range [r pttl key1] 9000 10000 }
+
+                flushallAndVerifyCleanup
+            }
+        }
+    }
+
+    test {DUMP/RESTORE: REPLACE with metadata} {
+        # Create key with metadata
+        r set key1 value1
+        r keymeta.set [cname 1] key1 "meta1_original"
+
+        # DUMP the key
+        set encoded1 [r dump key1]
+
+        # Create different key with different metadata
+        r set key1 value2
+        r keymeta.set [cname 1] key1 "meta1_new"
+
+        # DUMP the second version
+        set encoded2 [r dump key1]
+
+        # Delete and restore first version
+        r del key1
+        r restore key1 0 $encoded1
+        assert_equal [r get key1] "value1"
+        assert_equal [r keymeta.get [cname 1] key1] "meta1_original"
+
+        # RESTORE second version with REPLACE
+        r restore key1 0 $encoded2 replace
+        assert_equal [r get key1] "value2"
+        assert_equal [r keymeta.get [cname 1] key1] "meta1_new"
+
+        flushallAndVerifyCleanup
+    }
+
+
+    # Test all combinations except the error case (ALLOW_IGNORE=0, RDBLOAD=0, RDBSAVE=1)
+    foreach RDBLOAD {0 1} {
+        foreach RDBSAVE {0 1} {
+            foreach ALLOW_IGNORE {0 1} {
+                # Skip the error case - we'll test it last since it causes RESTORE to fail
+                if {!$RDBLOAD && $RDBSAVE && !$ALLOW_IGNORE} { continue }
+
+                test "DUMP/RESTORE: (ALLOW_IGNORE=$ALLOW_IGNORE, RDBLOAD=$RDBLOAD, RDBSAVE=$RDBSAVE)" {
+                    # re-register class 1 with new flags. Expected re-registered same class ID
+                    r keymeta.unregister [cname 1]
+                    # dummy default spec
+                    set newSpec "KEEPONCOPY"
+                    if {$ALLOW_IGNORE} { append newSpec ":ALLOWIGNORE" }
+                    if {$RDBLOAD} { append newSpec ":RDBLOAD" }
+                    if {$RDBSAVE} { append newSpec ":RDBSAVE" }
+
+                    # Must reuse same class-id that it had before
+                    assert_equal $classes(1) [r keymeta.register [cname 1] 1 $newSpec]
+
+                    r set key1 "value1"
+                    r keymeta.set [cname 1] key1 "key1_meta1"
+                    assert_equal [r keymeta.get [cname 1] key1] "key1_meta1"
+
+                    # DUMP & RESTORE
+                    set encoded [r dump key1]
+                    r del key1
+                    r restore key1 0 $encoded
+
+                    # Metadata is preserved only when BOTH rdb_save AND rdb_load are enabled
+                    # Otherwise metadata is lost (either not saved, or saved but not loaded)
+                    set metaPreserved [expr {$RDBSAVE && $RDBLOAD}]
+                    set expectedMeta [expr {$metaPreserved ? "key1_meta1" : ""}]
+
+                    assert_equal [r keymeta.get [cname 1] key1] $expectedMeta
+
+                    flushallAndVerifyCleanup
+                }
+            }
+        }
+    }
+
+    # Test the error case last (ALLOW_IGNORE=0, RDBLOAD=0, RDBSAVE=1)
+    # This test causes RESTORE to fail, so we test it last to avoid polluting subsequent tests
+    test "DUMP/RESTORE: Invalid combination: (ALLOW_IGNORE=0, RDBLOAD=0, RDBSAVE=1)" {
+        # re-register class 1 with RDBSAVE flag but no RDBLOAD or ALLOW_IGNORE
+        r keymeta.unregister [cname 1]
+        set newSpec "KEEPONCOPY:RDBSAVE"
+        assert_equal $classes(1) [r keymeta.register [cname 1] 1 $newSpec]
+
+        r set key1 "value1"
+        r keymeta.set [cname 1] key1 "key1_meta1"
+        assert_equal [r keymeta.get [cname 1] key1] "key1_meta1"
+
+        # DUMP the key
+        set encoded [r dump key1]
+
+        # Delete and try to RESTORE
+        r del key1
+
+        # This combination causes RESTORE to fail because:
+        # - Metadata was saved (RDBSAVE=1)
+        # - Class has no rdb_load callback (RDBLOAD=0)
+        # - Errors are not ignored (ALLOW_IGNORE=0)
+        catch {r restore key1 0 $encoded} err
+        assert_match "*Bad data format*" $err
+
+        flushallAndVerifyCleanup
+    }
+}
+
+test "RDB: Load with different module registration order preserves metadata correctly" {
+    # This test verifies out-of-order metadata attachment during RDB load.
+    # When modules register in different order at load time vs save time,
+    # metadata values should still be correctly associated with their classes.
+    start_server {tags {"modules" "external:skip" "cluster:skip"} overrides {enable-debug-command yes}} {
+        r module load $testmodule
+
+        # Helper function to generate class names (needed in inner scope)
+        proc cname {id} { return "CLS$id" }
+
+        # Register classes in order: 1, 2, 3
+        set spec1 "KEEPONCOPY:ALLOWIGNORE:RDBLOAD:RDBSAVE"
+        set spec2 "KEEPONRENAME:ALLOWIGNORE:RDBLOAD:RDBSAVE"
+        set spec3 "KEEPONMOVE:ALLOWIGNORE:RDBLOAD:RDBSAVE"
+
+        set class1 [r keymeta.register [cname 1] 1 $spec1]
+        set class2 [r keymeta.register [cname 2] 1 $spec2]
+        set class3 [r keymeta.register [cname 3] 1 $spec3]
+
+        # Verify class IDs match registration order
+        assert_equal $class1 1 "Class 1 registered first, gets ID 1"
+        assert_equal $class2 2 "Class 2 registered second, gets ID 2"
+        assert_equal $class3 3 "Class 3 registered third, gets ID 3"
+
+        # OUTER SERVER: Create RDB with classes registered in order 1,2,3
+        r flushall
+        r set mykey "myvalue"
+        r keymeta.set [cname 1] mykey "metadata_for_class1"
+        r keymeta.set [cname 2] mykey "metadata_for_class2"
+        r keymeta.set [cname 3] mykey "metadata_for_class3"
+
+        # Verify metadata before save
+        assert_equal [r keymeta.get [cname 1] mykey] "metadata_for_class1"
+        assert_equal [r keymeta.get [cname 2] mykey] "metadata_for_class2"
+        assert_equal [r keymeta.get [cname 3] mykey] "metadata_for_class3"
+
+        r save
+
+        # Get RDB file path & Copy RDB to a temp location with unique name
+        set rdb_dir [lindex [r config get dir] 1]
+        set rdb_file [lindex [r config get dbfilename] 1]
+        set rdb_path [file join $rdb_dir $rdb_file]
+        set temp_rdb [file join $rdb_dir "temp_metadata_outoforder_[pid].rdb"]
+        file copy -force $rdb_path $temp_rdb
+
+        # INNER SERVER: Start new server, register classes in DIFFERENT order, then load RDB
+        start_server [list overrides [list dir $rdb_dir enable-debug-command yes]] {
+            r module load $testmodule
+
+            # Helper function to generate class names (needed in inner scope)
+            proc cname {id} { return "CLS$id" }
+
+            # Register classes in DIFFERENT order: 3, 1, 2
+            # This simulates a server where modules load in different order
+            set spec1 "KEEPONCOPY:ALLOWIGNORE:RDBLOAD:RDBSAVE"
+            set spec2 "KEEPONRENAME:ALLOWIGNORE:RDBLOAD:RDBSAVE"
+            set spec3 "KEEPONMOVE:ALLOWIGNORE:RDBLOAD:RDBSAVE"
+
+            set class3 [r keymeta.register [cname 3] 1 $spec3]
+            set class1 [r keymeta.register [cname 1] 1 $spec1]
+            set class2 [r keymeta.register [cname 2] 1 $spec2]
+
+            # Verify class IDs are assigned by REGISTRATION ORDER, not name
+            # We registered in order 3,1,2, so the runtime IDs are:
+            # - class3 (name "CLS3") gets ID 1 (first registered)
+            # - class1 (name "CLS1") gets ID 2 (second registered)
+            # - class2 (name "CLS2") gets ID 3 (third registered)
+            # This is DIFFERENT from outer server which registered in order 1,2,3
+            assert_equal $class3 1 "Class 3 registered first, gets ID 1"
+            assert_equal $class1 2 "Class 1 registered second, gets ID 2"
+            assert_equal $class2 3 "Class 2 registered third, gets ID 3"
+
+            # Copy the saved RDB to this server's dbfilename
+            set inner_rdb_file [lindex [r config get dbfilename] 1]
+            set inner_rdb_path [file join $rdb_dir $inner_rdb_file]
+            file copy -force $temp_rdb $inner_rdb_path
+
+            # NOW load the RDB (AFTER registration in different order)
+            # Use 'nosave' to reload from the copied RDB without saving current state first
+            r debug reload nosave
+
+            # Verify the key exists
+            assert_equal [r exists mykey] 1 "Key should exist after RDB load"
+            assert_equal [r get mykey] "myvalue" "Key value should be preserved"
+
+            # Verify metadata values are correctly associated with their classes
+            # WITHOUT metadata would be swapped because:
+            # - At SAVE time (outer): classes registered in order 1,2,3
+            # - At LOAD time (inner): classes registered in order 3,1,2
+            # - RDB contains metadata in saved order, but keyMetaClassLookupByName
+            #   maps them back to correct classes by NAME, not by registration order
+            assert_equal [r keymeta.get [cname 1] mykey] "metadata_for_class1"
+            assert_equal [r keymeta.get [cname 2] mykey] "metadata_for_class2"
+            assert_equal [r keymeta.get [cname 3] mykey] "metadata_for_class3"
+        }
+
+        # Cleanup temp file
+        file delete $temp_rdb
+
+    }
+} {} {external:skip needs:save}
+
+test "RDB: File size same with/without metadata when no rdb_save callback" {
+    # This test verifies that when a metadata class has no rdb_save callback,
+    # the metadata is not serialized to RDB, so the RDB file size should be
+    # approximately the same (within a small tolerance for header differences).
+
+    start_server {tags {"modules" "external:skip" "cluster:skip"} overrides {enable-debug-command yes}} {
+        r module load $testmodule
+
+        # Get RDB directory
+        set rdb_dir [lindex [r config get dir] 1]
+        set rdb_file [lindex [r config get dbfilename] 1]
+        set rdb_path [file join $rdb_dir $rdb_file]
+
+        # Test 1: Create key WITHOUT metadata and save
+        r flushall
+        r set key1 "test_value_12345"
+        r save
+        set size_without_meta [file size $rdb_path]
+        
+        # Test 2: Create identical key WITH metadata (but no rdb_save) and save        
+        # Register a class WITHOUT rdb_save callback (RDBSAVE=0)
+        # Use ALLOWIGNORE so loading doesn't fail when metadata is missing
+        set spec "ALLOWIGNORE"
+        r keymeta.register [cname 1] 1 $spec
+        
+        r flushall
+        r set key1 "test_value_12345"
+        r keymeta.set [cname 1] key1 "some_metadata_value"
+
+        # Verify metadata is attached
+        assert_equal [r keymeta.get [cname 1] key1] "some_metadata_value"
+
+        r save
+        set size_with_meta [file size $rdb_path]
+
+        # The file sizes should be the same (metadata not serialized)
+        assert_equal $size_without_meta $size_with_meta
+    }
+} {} {external:skip needs:save}
+
+test "Creating key metadata not during OnLoad should fail" {
+    # This time start_server without "enable-debug-command yes"
+    start_server {tags {"modules" "external:skip" "cluster:skip"} overrides {enable-debug-command no}} {
+        r module load $testmodule
+        # Creating a class not during OnLoad should fail
+        catch {r keymeta.register [cname 1] 1 "ALLOWIGNORE"} err
+        assert_match {*failed to create metadata class*} $err        
+    }
+} {} {external:skip needs:save}