SERVER-36534 don't acquire locks on oplog when writing oplog entries

(cherry picked from commit 5c1a3ec728a71bca81629f99be782ac305a6ad4b)

6 files changed, 15 insertions, 18 deletions

diff --git a/jstests/disk/wt_missing_file_errors.js b/jstests/disk/wt_missing_file_errors.js
index 626974bbc30..3a9c783aad6 100644
--- a/jstests/disk/wt_missing_file_errors.js
+++ b/jstests/disk/wt_missing_file_errors.js
@@ -23,7 +23,7 @@
             MongoRunner.stopMongod(mongod);
             jsTestLog("deleting collection file: " + testCollFile);
             removeFile(testCollFile);
-        }, "Fatal Assertion 50883");
+        }, "Fatal Assertion 50882");
 
     /**
      * Test 2. Delete the _mdb_catalog.
@@ -35,7 +35,7 @@
             let mdbCatalogFile = dbpath + "_mdb_catalog.wt";
             jsTestLog("deleting catalog file: " + mdbCatalogFile);
             removeFile(mdbCatalogFile);
-        }, "Fatal Assertion 50883");
+        }, "Fatal Assertion 50882");
 
     /**
      * Test 3. Delete the WiredTiger.wt.
@@ -73,6 +73,6 @@
                 testColl.insert({a: 1});
             });
         },
-        "Fatal Assertion 50883");
+        "Fatal Assertion 50882");
 
 })();
diff --git a/src/mongo/db/catalog/collection_impl.cpp b/src/mongo/db/catalog/collection_impl.cpp
index c7b6427d777..e03e01599b9 100644
--- a/src/mongo/db/catalog/collection_impl.cpp
+++ b/src/mongo/db/catalog/collection_impl.cpp
@@ -323,7 +323,7 @@ Status CollectionImpl::insertDocumentsForOplog(OperationContext* opCtx,
                                                const DocWriter* const* docs,
                                                Timestamp* timestamps,
                                                size_t nDocs) {
-    dassert(opCtx->lockState()->isCollectionLockedForMode(ns().toString(), MODE_IX));
+    dassert(opCtx->lockState()->isWriteLocked());
 
     // Since this is only for the OpLog, we can assume these for simplicity.
     // This also means that we do not need to forward this object to the OpObserver, which is good
diff --git a/src/mongo/db/concurrency/write_conflict_exception.cpp b/src/mongo/db/concurrency/write_conflict_exception.cpp
index 202f17cf392..9ec06e31cec 100644
--- a/src/mongo/db/concurrency/write_conflict_exception.cpp
+++ b/src/mongo/db/concurrency/write_conflict_exception.cpp
@@ -59,8 +59,10 @@ void WriteConflictException::logAndBackoff(int attempt, StringData operation, St
         sleepmillis(1);
     } else if (attempt < 100) {
         sleepmillis(5);
-    } else {
+    } else if (attempt < 200) {
         sleepmillis(10);
+    } else {
+        sleepmillis(100);
     }
 }
 
diff --git a/src/mongo/db/repl/oplog.cpp b/src/mongo/db/repl/oplog.cpp
index 2ad84d776e9..d3f48954cd1 100644
--- a/src/mongo/db/repl/oplog.cpp
+++ b/src/mongo/db/repl/oplog.cpp
@@ -440,8 +440,6 @@ OpTime logOp(OperationContext* opCtx,
         return {};
     }
 
-    Lock::DBLock lk(opCtx, NamespaceString::kLocalDb, MODE_IX);
-    Lock::CollectionLock lock(opCtx->lockState(), _oplogCollectionName, MODE_IX);
     auto const oplog = _localOplogCollection;
 
     OplogSlot slot;
@@ -495,8 +493,6 @@ std::vector<OpTime> logInsertOps(OperationContext* opCtx,
     std::vector<OplogDocWriter> writers;
     writers.reserve(count);
     Collection* oplog = _localOplogCollection;
-    Lock::DBLock lk(opCtx, "local", MODE_IX);
-    Lock::CollectionLock lock(opCtx->lockState(), _oplogCollectionName, MODE_IX);
 
     WriteUnitOfWork wuow(opCtx);
 
diff --git a/src/mongo/db/storage/wiredtiger/wiredtiger_recovery_unit.cpp b/src/mongo/db/storage/wiredtiger/wiredtiger_recovery_unit.cpp
index 930cdba82c3..ae5962ac3b5 100644
--- a/src/mongo/db/storage/wiredtiger/wiredtiger_recovery_unit.cpp
+++ b/src/mongo/db/storage/wiredtiger/wiredtiger_recovery_unit.cpp
@@ -533,12 +533,6 @@ WiredTigerCursor::WiredTigerCursor(const std::string& uri,
     _ru = WiredTigerRecoveryUnit::get(opCtx);
     _session = _ru->getSession();
     _cursor = _session->getCursor(uri, tableId, forRecordStore);
-    if (!_cursor) {
-        // It could be an index file or a data file here.
-        error() << "Failed to get the cursor for uri: " << uri;
-        error() << "This may be due to missing data files. " << kWTRepairMsg;
-        fassertFailedNoTrace(50883);
-    }
 }
 
 WiredTigerCursor::~WiredTigerCursor() {
diff --git a/src/mongo/db/storage/wiredtiger/wiredtiger_session_cache.cpp b/src/mongo/db/storage/wiredtiger/wiredtiger_session_cache.cpp
index f617759d5dc..aaf59bdc5c3 100644
--- a/src/mongo/db/storage/wiredtiger/wiredtiger_session_cache.cpp
+++ b/src/mongo/db/storage/wiredtiger/wiredtiger_session_cache.cpp
@@ -37,6 +37,7 @@
 #include "mongo/db/storage/wiredtiger/wiredtiger_session_cache.h"
 
 #include "mongo/base/error_codes.h"
+#include "mongo/db/concurrency/write_conflict_exception.h"
 #include "mongo/db/global_settings.h"
 #include "mongo/db/repl/repl_settings.h"
 #include "mongo/db/server_parameters.h"
@@ -124,14 +125,18 @@ WT_CURSOR* WiredTigerSession::getCursor(const std::string& uri, uint64_t id, boo
     WT_CURSOR* c = NULL;
     int ret = _session->open_cursor(
         _session, uri.c_str(), NULL, forRecordStore ? "" : "overwrite=false", &c);
-    if (ret != ENOENT && ret != 0) {
+    if (ret == EBUSY) {
+        // This can only happen when trying to open a cursor on the oplog and it is currently locked
+        // by a verify or salvage, because we don't employ database locks to protect the oplog.
+        throw WriteConflictException();
+    }
+    if (ret != 0) {
         error() << "Failed to open a WiredTiger cursor: " << uri;
         error() << "This may be due to data corruption. " << kWTRepairMsg;
 
         fassertFailedNoTrace(50882);
     }
-    if (c)
-        _cursorsOut++;
+    _cursorsOut++;
     return c;
 }