Fix JDBC-179 by only resetting auto-commit conditionally

Author: seancorfield

CHANGES.md

@@ -1,3 +1,7 @@
+Changes in 0.7.11
+
+* Address edge case in transaction rollback failure [JDBC-179](https://clojure.atlassian.net/browse/JDBC-179).
+
 Changes in 0.7.10
 
 * Use a US-locale `lower-case` function to avoid problems in certain locales (e.g., Turkish). A similar issue has been fixed recently in both HoneySQL and `next.jdbc`.

README.md

@@ -1,7 +1,7 @@
 clojure.java.jdbc
 ========================================
 
-A low-level Clojure wrapper for JDBC-based access to databases. This project is "Stable" (no longer "Active"). It has effectively been superseded by [seancorfield/next.jdbc](https://github.com/seancorfield/next-jdbc). 
+A low-level Clojure wrapper for JDBC-based access to databases. This project is "Stable" (no longer "Active"). It has effectively been superseded by [seancorfield/next.jdbc](https://github.com/seancorfield/next-jdbc).
 
 For higher level DSLs and migration libraries that are compatible, see the [documentation](http://clojure-doc.org/articles/ecosystem/java_jdbc/home.html).
 
@@ -26,22 +26,22 @@ Support
 Releases and Dependency Information
 ========================================
 
-Latest stable release: 0.7.10 -- requires Clojure 1.7 or later!
+Latest stable release: 0.7.11 -- requires Clojure 1.7 or later!
 
 * [All Released Versions](http://search.maven.org/#search%7Cgav%7C1%7Cg%3A%22org.clojure%22%20AND%20a%3A%22java.jdbc%22)
 
 * [Development Snapshot Versions](https://oss.sonatype.org/index.html#nexus-search;gav~org.clojure~java.jdbc~~~)
 
 [Leiningen](https://github.com/technomancy/leiningen) dependency information:
 ```clojure
-[org.clojure/java.jdbc "0.7.10"]
+[org.clojure/java.jdbc "0.7.11"]
 ```
 [Maven](http://maven.apache.org/) dependency information:
 ```xml
 <dependency>
   <groupId>org.clojure</groupId>
   <artifactId>java.jdbc</artifactId>
-  <version>0.7.10</version>
+  <version>0.7.11</version>
 </dependency>
 ```
 _Note: Earlier versions of Clojure are supported by older versions of `clojure.java.jdbc`: e.g., version 0.6.1 supports Clojure 1.4 and later._
@@ -140,6 +140,9 @@ Developer Information
 Change Log
 ====================
 
+* Release 0.7.11 on 2019-12-24
+  * Address edge case in transaction rollback failure [JDBC-179](https://clojure.atlassian.net/browse/JDBC-179).
+
 * Release 0.7.10 on 2019-08-24
   * Use a US-locale `lower-case` function to avoid problems in certain locales (e.g., Turkish). A similar issue has been fixed recently in both HoneySQL and `next.jdbc`.
   * Clean up `db-spec` options that are passed to the JDBC connection manager as properties [JDBC-178](https://clojure.atlassian.net/browse/JDBC-178).

src/main/clojure/clojure/java/jdbc.clj

@@ -793,9 +793,10 @@ http://clojure-doc.org/articles/ecosystem/java_jdbc/home.html"}
      (if (zero? (get-level db))
        (if-let [con (db-find-connection db)]
          (let [nested-db (inc-level db)
-               auto-commit (.getAutoCommit con)
+               auto-commit   (.getAutoCommit con)
                old-isolation (.getTransactionIsolation con)
-               old-readonly  (.isReadOnly con)]
+               old-readonly  (.isReadOnly con)
+               restore-ac?   (volatile! true)]
            (io!
             (when isolation
               (.setTransactionIsolation con (isolation isolation-levels)))
@@ -805,12 +806,21 @@ http://clojure-doc.org/articles/ecosystem/java_jdbc/home.html"}
             (try
               (let [result (func nested-db)]
                 (if (db-is-rollback-only nested-db)
-                  (.rollback con)
+                  (do
+                    ;; per JDBC-179: if the rollback operation fails, we do not
+                    ;; want to try to restore auto-commit...
+                    (vreset! restore-ac? false)
+                    (.rollback con)
+                    (vreset! restore-ac? true))
                   (.commit con))
                 result)
               (catch Throwable t
                 (try
+                  ;; per JDBC-179: if the rollback operation fails, we do not
+                  ;; want to try to restore auto-commit...
+                  (vreset! restore-ac? false)
                   (.rollback con)
+                  (vreset! restore-ac? true)
                   (catch Throwable rb
                     ;; combine both exceptions
                     (throw (ex-info (str "Rollback failed handling \""
@@ -825,9 +835,10 @@ http://clojure-doc.org/articles/ecosystem/java_jdbc/home.html"}
                 ;; want those to replace any exception currently being
                 ;; handled -- and if the connection got closed, we just
                 ;; want to ignore exceptions here anyway
-                (try
-                  (.setAutoCommit con auto-commit)
-                  (catch Exception _))
+                (when @restore-ac?
+                  (try ; only restore auto-commit if rollback did not fail
+                    (.setAutoCommit con auto-commit)
+                    (catch Exception _)))
                 (when isolation
                   (try
                     (.setTransactionIsolation con old-isolation)