Bug 834449 - Part 2: clean up cached statements in Sqlite.jsm. r=gps

toolkit/modules/Sqlite.jsm

@@ -731,6 +731,26 @@ OpenedConnection.prototype = Object.freeze({
     return this.execute("PRAGMA shrink_memory").then(onShrunk, onShrunk);
   },
 
+  /**
+   * Discard all inactive cached statements.
+   *
+   * @return (integer) the number of statements discarded.
+   */
+  discardCachedStatements: function () {
+    let count = 0;
+    for (let [k, statement] of this._cachedStatements) {
+      if (this.inProgress(statement)) {
+        continue;
+      }
+
+      ++count;
+      this._cachedStatements.delete(k);
+      statement.finalize();
+    }
+    this._log.debug("Discarded " + count + " cached statements.");
+    return count;
+  },
+
   _executeStatement: function (sql, statement, params, onRow) {
     if (statement.state != statement.MOZ_STORAGE_STATEMENT_READY) {
       throw new Error("Statement is not ready for execution.");

toolkit/modules/tests/xpcshell/test_sqlite.js

@@ -528,3 +528,50 @@ add_task(function test_in_progress_counts() {
   yield c.close();
 });
 
+add_task(function test_discard_while_active() {
+  let c = yield getDummyDatabase("discard_while_active");
+
+  yield c.executeCached("INSERT INTO dirs (path) VALUES ('foo')");
+  yield c.executeCached("INSERT INTO dirs (path) VALUES ('bar')");
+
+  let discarded = -1;
+  let first = true;
+  let sql = "SELECT * FROM dirs";
+  yield c.executeCached(sql, null, function onRow(row) {
+    if (!first) {
+      return;
+    }
+    first = false;
+    discarded = c.discardCachedStatements();
+  });
+
+  // We didn't discard the SELECT, only the two INSERTs.
+  do_check_eq(2, discarded);
+
+  // But we got the remainder when it became inactive.
+  do_check_eq(1, c.discardCachedStatements());
+
+  // And again is safe.
+  do_check_eq(0, c.discardCachedStatements());
+
+  yield c.close();
+});
+
+add_task(function test_discard_cached() {
+  let c = yield getDummyDatabase("discard_cached");
+
+  yield c.executeCached("SELECT * from dirs");
+  do_check_eq(1, c._cachedStatements.size);
+
+  yield c.executeCached("SELECT * from files");
+  do_check_eq(2, c._cachedStatements.size);
+
+  yield c.executeCached("SELECT * from dirs");
+  do_check_eq(2, c._cachedStatements.size);
+
+  c.discardCachedStatements();
+  do_check_eq(0, c._cachedStatements.size);
+
+  yield c.close();
+});
+