SERVER-32001 Fix unindexing of rollback in unique partial indexes

jstests/noPassthrough/partial_unique_indexes.js

@@ -0,0 +1,47 @@
+/**
+ * SERVER-32001: Test that indexing paths for non-unique, partial, unique, partial&unique
+ * crud operations correctly handle WriteConflictExceptions.
+ */
+(function() {
+    "strict";
+
+    let conn = MongoRunner.runMongod();
+    let testDB = conn.getDB("test");
+
+    let t = testDB.jstests_parallel_allops;
+    t.drop();
+
+    t.createIndex({x: 1, _id: 1}, {partialFilterExpression: {_id: {$lt: 500}}, unique: true});
+    t.createIndex({y: -1, _id: 1}, {unique: true});
+    t.createIndex({x: -1}, {partialFilterExpression: {_id: {$gte: 500}}, unique: false});
+    t.createIndex({y: 1}, {unique: false});
+
+    let _id = {"#RAND_INT": [0, 1000]};
+    let ops = [
+        {op: "remove", ns: t.getFullName(), query: {_id}},
+        {op: "update", ns: t.getFullName(), query: {_id}, update: {$inc: {x: 1}}, upsert: true},
+        {op: "update", ns: t.getFullName(), query: {_id}, update: {$inc: {y: 1}}, upsert: true},
+    ];
+
+    let seconds = 5;
+    let parallel = 5;
+    let host = testDB.getMongo().host;
+
+    let benchArgs = {ops, seconds, parallel, host};
+
+    assert.commandWorked(testDB.adminCommand({
+        configureFailPoint: 'WTWriteConflictExceptionForReads',
+        mode: {activationProbability: 0.01}
+    }));
+    assert.commandWorked(testDB.adminCommand(
+        {configureFailPoint: 'WTWriteConflictException', mode: {activationProbability: 0.01}}));
+    res = benchRun(benchArgs);
+    printjson({res});
+
+    assert.commandWorked(
+        testDB.adminCommand({configureFailPoint: 'WTWriteConflictException', mode: "off"}));
+    assert.commandWorked(
+        testDB.adminCommand({configureFailPoint: 'WTWriteConflictExceptionForReads', mode: "off"}));
+    res = t.validate();
+    assert(res.valid, tojson(res));
+})();

src/mongo/db/storage/wiredtiger/wiredtiger_index.cpp

@@ -1213,6 +1213,7 @@ void WiredTigerIndexUnique::_unindex(WT_CURSOR* c,
                 triggerWriteConflictAtPoint(c);
                 return;
             }
+            invariantWTOK(ret);
             WT_ITEM value;
             invariantWTOK(c->get_value(c, &value));
             BufReader br(value.data, value.size);