From 09df6647acc4611f670e0f972e6b70b56dac0e25 Mon Sep 17 00:00:00 2001
From: Anshum Gupta <anshum@apache.org>
Date: Wed, 4 Dec 2019 01:19:56 +0530
Subject: [PATCH] SOLR-13998: Add thread safety annotations to classes (#1053)

---
 solr/CHANGES.txt                              |  3 ++
 .../common/annotation/SolrSingleThreaded.java | 34 ++++++++++++++++++
 .../common/annotation/SolrThreadSafe.java     | 35 +++++++++++++++++++
 3 files changed, 72 insertions(+)
 create mode 100644 solr/solrj/src/java/org/apache/solr/common/annotation/SolrSingleThreaded.java
 create mode 100644 solr/solrj/src/java/org/apache/solr/common/annotation/SolrThreadSafe.java

diff --git a/solr/CHANGES.txt b/solr/CHANGES.txt
index 24d0c5d473f..4e213d32b45 100644
--- a/solr/CHANGES.txt
+++ b/solr/CHANGES.txt
@@ -223,6 +223,9 @@ Other Changes
 
 * SOLR-13992: Code refactored to have collection name, slice name in Replica, Slice (noble)
 
+* SOLR-13998: Add thread safety annotations to Solr. This only introduces the annotations and doesn't add these to
+  existing classes. (Anshum Gupta, Mark Miller)
+
 ==================  8.3.1 ==================
 
 Consult the LUCENE_CHANGES.txt file for additional, low level, changes in this release.
diff --git a/solr/solrj/src/java/org/apache/solr/common/annotation/SolrSingleThreaded.java b/solr/solrj/src/java/org/apache/solr/common/annotation/SolrSingleThreaded.java
new file mode 100644
index 00000000000..3845468ef4d
--- /dev/null
+++ b/solr/solrj/src/java/org/apache/solr/common/annotation/SolrSingleThreaded.java
@@ -0,0 +1,34 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements.  See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.
+ * The ASF licenses this file to You under the Apache License, Version 2.0
+ * (the "License"); you may not use this file except in compliance with
+ * the License.  You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.apache.solr.common.annotation;
+
+import static java.lang.annotation.ElementType.TYPE;
+import static java.lang.annotation.RetentionPolicy.SOURCE;
+
+import java.lang.annotation.Documented;
+import java.lang.annotation.Retention;
+import java.lang.annotation.Target;
+
+/**
+ * Annotation for classes in Solr that are not thread safe. This provides a clear indication of the thread safety of the class.
+ */
+@Documented
+@Retention(SOURCE)
+@Target(TYPE)
+public @interface SolrSingleThreaded {
+
+}
diff --git a/solr/solrj/src/java/org/apache/solr/common/annotation/SolrThreadSafe.java b/solr/solrj/src/java/org/apache/solr/common/annotation/SolrThreadSafe.java
new file mode 100644
index 00000000000..8c2ef48d536
--- /dev/null
+++ b/solr/solrj/src/java/org/apache/solr/common/annotation/SolrThreadSafe.java
@@ -0,0 +1,35 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements.  See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.
+ * The ASF licenses this file to You under the Apache License, Version 2.0
+ * (the "License"); you may not use this file except in compliance with
+ * the License.  You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.apache.solr.common.annotation;
+
+import static java.lang.annotation.ElementType.TYPE;
+import static java.lang.annotation.RetentionPolicy.SOURCE;
+
+import java.lang.annotation.Documented;
+import java.lang.annotation.Retention;
+import java.lang.annotation.Target;
+
+/**
+ * This annotation is applied to a class that is thread safe. This means that the objects of this class will never be
+ * in an inconsistent state, irrespective of interleaving accesses to the object.
+ */
+@Documented
+@Retention(SOURCE)
+@Target(TYPE)
+public @interface SolrThreadSafe {
+
+}