SERVER-16442 test difference in meaning of w: majority in mixed mode replicasets

2 files changed, 155 insertions, 2 deletions

diff --git a/jstests/multiVersion/w_majority_change.js b/jstests/multiVersion/w_majority_change.js
new file mode 100644
index 00000000000..739bc8e5f21
--- /dev/null
+++ b/jstests/multiVersion/w_majority_change.js
@@ -0,0 +1,153 @@
+// exemplify and test the difference in meaning of w: "majority" between 2.6 and 2.8
+
+load("jstests/replsets/rslib.js");
+
+(function() {
+    "use strict";
+    var newVersion = "latest";
+    var oldVersion = "2.6";
+
+    // this first 7-node configuration will consist of 4 arbiters, 2 voting, non-arbiter nodes,
+    // and 1 non-voting, non-arbiter node
+    var name = "write_concern_many_arbiters";
+    var nodes = {n0: {binVersion: newVersion},
+                 n1: {binVersion: newVersion},
+                 n2: {binVersion: oldVersion},
+                 n3: {binVersion: oldVersion},
+                 n4: {binVersion: oldVersion},
+                 n5: {binVersion: newVersion},
+                 n6: {binVersion: newVersion}};
+
+    var replTest = new ReplSetTest({name: name, nodes: nodes});
+    nodes = replTest.startSet();
+    var config = {_id: name,
+                  version: 1,
+                  members: [{_id:0, host: nodes[0].host, priority: 3, votes: 1},
+                            {_id:1, host: nodes[1].host, priority: 0, votes: 0},
+                            {_id:2, host: nodes[2].host, priority: 0, votes: 1},
+                            {_id:3, host: nodes[3].host, votes: 1, arbiterOnly: true},
+                            {_id:4, host: nodes[4].host, votes: 1, arbiterOnly: true},
+                            {_id:5, host: nodes[5].host, votes: 1, arbiterOnly: true},
+                            {_id:6, host: nodes[6].host, votes: 1, arbiterOnly: true},
+                           ],
+                  };
+    replTest.initiate(config);
+
+    var writeConcern = {writeConcern: {w: "majority", wtimeout: 9*1000}};
+    var primary = replTest.getPrimary();
+    primary.forceWriteMode("commands");
+    assert.eq(primary.host, nodes[0].host, "2.8 node failed to become primary");
+
+    // w: majority on node 0 (2.8) will need both voting, non-arbiter nodes in this configuration
+    // take down one voting, non-arbiter node. fails because we are missing a voter
+    replTest.stop(2);
+    assert.writeError(primary.getDB(name).foo.insert({x: 1}, writeConcern));
+    // bring it back
+    replTest.restart(2);
+    assert.writeOK(primary.getDB(name).foo.insert({x: 2}, writeConcern));
+    // take down one non-voting, non-arbiter node. passes because the non-voter does not matter
+    replTest.stop(1);
+    assert.writeOK(primary.getDB(name).foo.insert({x: 3}, writeConcern));
+    replTest.restart(1);
+
+    // reconfig such that a 2.6 node (node 2) will be primary
+    config.version++;
+    config.members[0].priority = 0;
+    config.members[2].priority = 3;
+
+    reconfig(replTest, config, true);
+    primary = replTest.getPrimary();
+    assert.eq(primary.host, nodes[2].host, "2.6 node failed to become primary");
+    primary.forceWriteMode("commands");
+
+    // w: majority on 2.6 will need all non-arbiter nodes in this configuration
+    // take down one voting, non-arbiter node. fails because all nodes are needed
+    replTest.stop(0);
+    assert.writeError(primary.getDB(name).foo.insert({x: 4}, writeConcern));
+    // bring it back
+    replTest.restart(0);
+    assert.writeOK(primary.getDB(name).foo.insert({x: 5}, writeConcern));
+    // take down one non-voting, non-arbiter node. fails because all nodes are needed
+    replTest.stop(1);
+    assert.writeError(primary.getDB(name).foo.insert({x: 6}, writeConcern));
+
+    replTest.stopSet();
+
+    // this second 7-node configuration will consist of 1 arbiter, 4 voting, non-arbiter nodes, and
+    // 2 non-voting, non-arbiter nodes
+    name = "write_concern_few_arbiters";
+    nodes = {n0: {binVersion: newVersion},
+             n1: {binVersion: newVersion},
+             n2: {binVersion: oldVersion},
+             n3: {binVersion: oldVersion},
+             n4: {binVersion: oldVersion},
+             n5: {binVersion: newVersion},
+             n6: {binVersion: newVersion}};
+
+    replTest = new ReplSetTest({name: name, nodes: nodes});
+    nodes = replTest.startSet();
+    config = {_id: name,
+              version: 1,
+              members: [{_id:0, host: nodes[0].host, priority: 3, votes: 1},
+                        {_id:1, host: nodes[1].host, priority: 0, votes: 1},
+                        {_id:2, host: nodes[2].host, priority: 0, votes: 1},
+                        {_id:3, host: nodes[3].host, priority: 0, votes: 1},
+                        {_id:4, host: nodes[4].host, priority: 0, votes: 0},
+                        {_id:5, host: nodes[5].host, priority: 0, votes: 0},
+                        {_id:6, host: nodes[6].host, votes: 1, arbiterOnly: true},
+                       ],
+              };
+    replTest.initiate(config);
+
+    var primary = replTest.getPrimary();
+    primary.forceWriteMode("commands");
+    assert.eq(primary.host, nodes[0].host, "2.8 node failed to become primary");
+
+    // w: majority on node 0 (2.8) will need 3 voting, non-arbiter nodes in this configuration
+    // take down both non-voting nodes. passes because non-voting nodes do not matter
+    replTest.stop(5);
+    replTest.stop(4);
+    assert.writeOK(primary.getDB(name).foo.insert({x: 7}, writeConcern));
+    // take down one voting node. passes because we still have sufficient voting nodes
+    replTest.stop(3);
+    assert.writeOK(primary.getDB(name).foo.insert({x: 8}, writeConcern));
+    // take down another voting node. fails because we have insufficient voting nodes
+    replTest.stop(2);
+    assert.writeError(primary.getDB(name).foo.insert({x: 9}, writeConcern));
+    // bring back both non-voting nodes. fails because non-voters still do not matter
+    replTest.restart(5);
+    replTest.restart(4);
+    assert.writeError(primary.getDB(name).foo.insert({x: 10}, writeConcern));
+    // bring back a voting node. passes because we have sufficient voting nodes
+    replTest.restart(3);
+    assert.writeOK(primary.getDB(name).foo.insert({x: 11}, writeConcern));
+    replTest.restart(2);
+
+
+    // reconfig such that a 2.6 node (node 2) will be primary
+    config.version++;
+    config.members[0].priority = 0;
+    config.members[2].priority = 3;
+
+    reconfig(replTest, config, true);
+    primary = replTest.getPrimary();
+    assert.eq(primary.host, nodes[2].host, "2.6 node failed to become primary");
+    primary.forceWriteMode("commands");
+
+    // w: majority on 2.6 will need 4 non-arbiter nodes in this configuration
+    // take down both non-voting nodes. passes because there are still sufficient nodes
+    replTest.stop(5);
+    replTest.stop(4);
+    assert.writeOK(primary.getDB(name).foo.insert({x: 12}, writeConcern));
+    // take down one voting node. fails because there are insufficient nodes
+    replTest.stop(3);
+    assert.writeError(primary.getDB(name).foo.insert({x: 13}, writeConcern));
+    // bring up both non-voting nodes and take down a voting one
+    // passes because only number of nodes matters in 2.6, not voting like in 2.8
+    replTest.restart(5);
+    replTest.restart(4);
+    replTest.stop(1);
+    assert.writeOK(primary.getDB(name).foo.insert({x: 15}, writeConcern));
+
+    replTest.stopSet();
+}());
diff --git a/jstests/replsets/rslib.js b/jstests/replsets/rslib.js
index f926640e2c5..bb3b8374738 100644
--- a/jstests/replsets/rslib.js
+++ b/jstests/replsets/rslib.js
@@ -100,13 +100,13 @@ waitForAllMembers = function(master, timeout) {
     print( "All members are now in state PRIMARY, SECONDARY, or ARBITER" );
 };
 
-reconfig = function(rs, config) {
+reconfig = function(rs, config, force) {
     "use strict";
     var admin = rs.getMaster().getDB("admin");
     var e;
     var master;
     try {
-        assert.commandWorked(admin.runCommand({replSetReconfig : config}));
+        assert.commandWorked(admin.runCommand({replSetReconfig: config, force: force}));
     }
     catch (e) {
         if (tojson(e).indexOf( "error doing query: failed" ) < 0) {