MB-33840: Revert "MB-33684: Convert VB::Manifest lock to folly::SharedMutex"

This reverts commit 0dfa085 and 
commit 27e3aa7.


Change-Id: If45017cbe923908e1cd52884b5266c8134a4289f
Reviewed-on: http://review.couchbase.org/107642
Tested-by: Build Bot <[email protected]>
Reviewed-by: Dave Rigby <[email protected]>

Author: BenHuddleston

engines/ep/src/collections/vbucket_manifest.cc

@@ -871,8 +871,8 @@ boost::optional<std::vector<CollectionID>> Manifest::getCollectionsForScope(
 }
 
 bool Manifest::operator==(const Manifest& rhs) const {
-    mutex_type::ReadHolder readLock(rwlock);
-    mutex_type::ReadHolder otherReadLock(rhs.rwlock);
+    std::lock_guard<cb::ReaderLock> readLock(rwlock.reader());
+    std::lock_guard<cb::ReaderLock> otherReadLock(rhs.rwlock.reader());
 
     if (rhs.map.size() != map.size()) {
         return false;

engines/ep/src/collections/vbucket_manifest.h

@@ -24,7 +24,6 @@
 #include "systemevent.h"
 
 #include <boost/optional/optional_fwd.hpp>
-#include <folly/SharedMutex.h>
 #include <platform/non_negative_counter.h>
 #include <platform/rwlock.h>
 #include <platform/sized_buffer.h>
@@ -34,7 +33,6 @@
 #include <list>
 #include <mutex>
 #include <set>
-#include <shared_mutex>
 #include <unordered_map>
 
 class VBucket;
@@ -81,7 +79,6 @@ namespace VB {
 class Manifest {
 public:
     using container = ::std::unordered_map<CollectionID, ManifestEntry>;
-    using mutex_type = folly::SharedMutex;
 
     /**
      * RAII read locking for access to the Manifest.
@@ -98,7 +95,7 @@ class Manifest {
          */
         ReadHandle() = default;
 
-        ReadHandle(const Manifest* m, mutex_type& lock)
+        ReadHandle(const Manifest* m, cb::RWLock& lock)
             : readLock(lock), manifest(m) {
         }
 
@@ -260,7 +257,7 @@ class Manifest {
     protected:
         friend std::ostream& operator<<(std::ostream& os,
                                         const Manifest::ReadHandle& readHandle);
-        std::shared_lock<mutex_type> readLock;
+        std::unique_lock<cb::ReaderLock> readLock;
         const Manifest* manifest;
     };
 
@@ -292,7 +289,7 @@ class Manifest {
          *        should not be allowed, whereas a disk backfill is allowed
          */
         CachingReadHandle(const Manifest* m,
-                          mutex_type& lock,
+                          cb::RWLock& lock,
                           DocKey key,
                           bool allowSystem)
             : ReadHandle(m, lock),
@@ -469,7 +466,7 @@ class Manifest {
      */
     class StatsReadHandle : private ReadHandle {
     public:
-        StatsReadHandle(const Manifest* m, mutex_type& lock, CollectionID cid)
+        StatsReadHandle(const Manifest* m, cb::RWLock& lock, CollectionID cid)
             : ReadHandle(m, lock), itr(m->getManifestIterator(cid)) {
         }
 
@@ -503,7 +500,7 @@ class Manifest {
      */
     class WriteHandle {
     public:
-        WriteHandle(Manifest& m, mutex_type& lock)
+        WriteHandle(Manifest& m, cb::RWLock& lock)
             : writeLock(lock), manifest(m) {
         }
 
@@ -644,7 +641,7 @@ class Manifest {
         }
 
     private:
-        mutex_type::WriteHolder writeLock;
+        std::unique_lock<cb::WriterLock> writeLock;
         Manifest& manifest;
     };
 
@@ -1256,7 +1253,7 @@ class Manifest {
     /**
      * shared lock to allow concurrent readers and safe updates
      */
-    mutable mutex_type rwlock;
+    mutable cb::RWLock rwlock;
 
     friend std::ostream& operator<<(std::ostream& os, const Manifest& manifest);
 

engines/ep/tests/module_tests/collections/vbucket_manifest_test.cc

@@ -37,19 +37,19 @@ class MockVBManifest : public Collections::VB::Manifest {
     }
 
     bool exists(CollectionID identifier) const {
-        mutex_type::ReadHolder readLock(rwlock);
+        std::lock_guard<cb::ReaderLock> readLock(rwlock.reader());
         return exists_UNLOCKED(identifier);
     }
 
     size_t size() const {
-        mutex_type::ReadHolder readLock(rwlock);
+        std::lock_guard<cb::ReaderLock> readLock(rwlock.reader());
         return map.size();
     }
 
     bool compareEntry(CollectionID id,
                       const Collections::VB::ManifestEntry& entry,
                       bool ignoreHighSeqno = false) const {
-        mutex_type::ReadHolder readLock(rwlock);
+        std::lock_guard<cb::ReaderLock> readLock(rwlock.reader());
         if (exists_UNLOCKED(id)) {
             auto itr = map.find(id);
             const auto& myEntry = itr->second;
@@ -75,7 +75,7 @@ class MockVBManifest : public Collections::VB::Manifest {
     }
 
     bool operator==(const MockVBManifest& rhs) const {
-        mutex_type::ReadHolder readLock(rwlock);
+        std::lock_guard<cb::ReaderLock> readLock(rwlock.reader());
         if (rhs.size() != size()) {
             return false;
         }