SERVER-37001 Add idleCursor to $currentOp

1 files changed, 61 insertions, 0 deletions

diff --git a/jstests/libs/pin_getmore_cursor.js b/jstests/libs/pin_getmore_cursor.js
new file mode 100644
index 00000000000..d362eb347fa
--- /dev/null
+++ b/jstests/libs/pin_getmore_cursor.js
@@ -0,0 +1,61 @@
+/**
+ * Pins a cursor in a seperate shell and then runs the given function.
+ * 'conn': a connection to an instance of a mongod or mongos.
+ * 'assertFunction': a function containing the test to be run after a cursor is pinned and hanging.
+ * 'runGetMoreFunc': A function to generate a string that will be executed in the parallel shell.
+ * 'failPointName': The string name of the failpoint where the cursor will hang. The function turns
+ * the failpoint on, the assert function should turn it off whenever it is appropriate for the test.
+ */
+
+function withPinnedCursor({conn, assertFunction, runGetMoreFunc, failPointName}) {
+    // This test runs manual getMores using different connections, which will not inherit the
+    // implicit session of the cursor establishing command.
+    TestData.disableImplicitSessions = true;
+
+    const db = conn.getDB("test");
+    const coll = db.jstest_with_pinned_cursor;
+    coll.drop();
+    for (let i = 0; i < 100; ++i) {
+        assert.writeOK(coll.insert({value: i}));
+    }
+    let cleanup = null;
+    try {
+        // Enable the specified failpoint.
+        assert.commandWorked(
+            db.adminCommand({configureFailPoint: failPointName, mode: "alwaysOn"}));
+        // Issue an initial find in order to create a cursor and obtain its cursorID.
+        let cmdRes = db.runCommand({find: coll.getName(), batchSize: 2});
+        assert.commandWorked(cmdRes);
+        let cursorId = cmdRes.cursor.id;
+        assert.neq(cursorId, NumberLong(0));
+        // Let the cursor hang in a different shell
+        let code = "let cursorId = " + cursorId.toString() + ";";
+        code += "let collName = '" + coll.getName() + "';";
+        code += "(" + runGetMoreFunc.toString() + ")();";
+        cleanup = startParallelShell(code, conn.port);
+        // Wait until we know the failpoint has been reached.
+        assert.soon(function() {
+            const arr =
+                db.getSiblingDB("admin")
+                    .aggregate([{$currentOp: {localOps: true}}, {$match: {"msg": failPointName}}])
+                    .toArray();
+            return arr.length > 0;
+        });
+        assertFunction(cursorId, coll);
+        // Eventually the cursor should be cleaned up.
+        assert.commandWorked(db.adminCommand({configureFailPoint: failPointName, mode: "off"}));
+        assert.soon(() => db.serverStatus().metrics.cursor.open.pinned == 0);
+
+        // Trying to kill the cursor again should result in the cursor not being found.
+        cmdRes = db.runCommand({killCursors: coll.getName(), cursors: [cursorId]});
+        assert.commandWorked(cmdRes);
+        assert.eq(cmdRes.cursorsKilled, []);
+        assert.eq(cmdRes.cursorsAlive, []);
+        assert.eq(cmdRes.cursorsNotFound, [cursorId]);
+        assert.eq(cmdRes.cursorsUnknown, []);
+    } finally {
+        if (cleanup) {
+            cleanup();
+        }
+    }
+}