Optimized Cache::Entry should support old dalli_store values

Same bug as rails#42559, but a very different fix due to rails#42025. To recap, the issue:

- While using the `dalli_store`, you set any value in the Rails cache with no expiry.
- You change to the `mem_cache_store`.
- You upgrade to Rails 7.
- You try to read the same cache key you set in step 1, and it crashes on read.

rails#42025 was backward compatible with entries written using the `mem_cache_store`, but *not* the `dalli_store` which did not use `ActiveSupport::Cache::Entry`. This PR attempts to fix that.

activesupport/lib/active_support/cache.rb

@@ -844,14 +844,20 @@ module Loader
         extend self
 
         def load(payload)
-          if payload.start_with?(MARK_70_UNCOMPRESSED)
+          if !payload.is_a?(String)
+            ActiveSupport::Cache::Store.logger&.warn %{Payload wasn't a string, was #{payload.class.name} - couldn't unmarshal, so returning nil."}
+
+            return nil
+          elsif payload.start_with?(MARK_70_UNCOMPRESSED)
             members = Marshal.load(payload.byteslice(1..-1))
           elsif payload.start_with?(MARK_70_COMPRESSED)
             members = Marshal.load(Zlib::Inflate.inflate(payload.byteslice(1..-1)))
           elsif payload.start_with?(MARK_61)
             return Marshal.load(payload)
           else
-            raise ArgumentError, %{Invalid cache prefix: #{payload.byteslice(0).inspect}, expected "\\x00" or "\\x01"}
+            ActiveSupport::Cache::Store.logger&.warn %{Invalid cache prefix: #{payload.byteslice(0).inspect}, expected "\\x00" or "\\x01"}
+
+            return nil
           end
           Entry.unpack(members)
         end

activesupport/test/cache/behaviors/local_cache_behavior.rb

@@ -228,4 +228,11 @@ def test_local_race_condition_protection
       end
     end
   end
+
+  def test_local_cache_should_read_and_write_false
+    @cache.with_local_cache do
+      assert @cache.write("foo", false)
+      assert_equal false, @cache.read("foo")
+    end
+  end
 end

activesupport/test/cache/stores/mem_cache_store_test.rb

@@ -232,6 +232,42 @@ def test_large_object_with_default_compression_settings
     assert_compressed(LARGE_OBJECT)
   end
 
+  def test_can_load_raw_values_from_dalli_store
+    key = "test-with-value-the-way-the-dalli-store-did"
+
+    @cache.instance_variable_get(:@data).with { |c| c.set(@cache.send(:normalize_key, key, nil), "value", 0, compress: false) }
+    assert_nil @cache.read(key)
+    assert_equal "value", @cache.fetch(key) { "value" }
+  end
+
+  def test_can_load_raw_falsey_values_from_dalli_store
+    key = "test-with-false-value-the-way-the-dalli-store-did"
+
+    @cache.instance_variable_get(:@data).with { |c| c.set(@cache.send(:normalize_key, key, nil), false, 0, compress: false) }
+    assert_nil @cache.read(key)
+    assert_equal false, @cache.fetch(key) { false }
+  end
+
+  def test_can_load_raw_values_from_dalli_store_with_local_cache
+    key = "test-with-value-the-way-the-dalli-store-did-with-local-cache"
+
+    @cache.instance_variable_get(:@data).with { |c| c.set(@cache.send(:normalize_key, key, nil), "value", 0, compress: false) }
+    @cache.with_local_cache do
+      assert_nil @cache.read(key)
+      assert_equal "value", @cache.fetch(key) { "value" }
+    end
+  end
+
+  def test_can_load_raw_falsey_values_from_dalli_store_with_local_cache
+    key = "test-with-false-value-the-way-the-dalli-store-did-with-local-cache"
+
+    @cache.instance_variable_get(:@data).with { |c| c.set(@cache.send(:normalize_key, key, nil), false, 0, compress: false) }
+    @cache.with_local_cache do
+      assert_nil @cache.read(key)
+      assert_equal false, @cache.fetch(key) { false }
+    end
+  end
+
   private
     def random_string(length)
       (0...length).map { (65 + rand(26)).chr }.join