1 //===------------------SharedCluster.h --------------------------*- C++ -*-===//
2 //
3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4 // See https://llvm.org/LICENSE.txt for license information.
5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6 //
7 //===----------------------------------------------------------------------===//
8 
9 #ifndef LLDB_UTILITY_SHAREDCLUSTER_H
10 #define LLDB_UTILITY_SHAREDCLUSTER_H
11 
12 #include "lldb/Utility/LLDBAssert.h"
13 #include "llvm/ADT/STLExtras.h"
14 #include "llvm/ADT/SmallPtrSet.h"
15 
16 #include <memory>
17 #include <mutex>
18 
19 namespace lldb_private {
20 
21 template <class T>
22 class ClusterManager : public std::enable_shared_from_this<ClusterManager<T>> {
23 public:
Create()24   static std::shared_ptr<ClusterManager> Create() {
25     return std::shared_ptr<ClusterManager>(new ClusterManager());
26   }
27 
~ClusterManager()28   ~ClusterManager() {
29     for (T *obj : m_objects)
30       delete obj;
31   }
32 
ManageObject(T * new_object)33   void ManageObject(T *new_object) {
34     std::lock_guard<std::mutex> guard(m_mutex);
35     auto ret = m_objects.insert(new_object);
36     assert(ret.second && "ManageObject called twice for the same object?");
37     (void)ret;
38   }
39 
GetSharedPointer(T * desired_object)40   std::shared_ptr<T> GetSharedPointer(T *desired_object) {
41     std::lock_guard<std::mutex> guard(m_mutex);
42     auto this_sp = this->shared_from_this();
43     size_t count =  m_objects.count(desired_object);
44     if (count == 0) {
45       lldbassert(false && "object not found in shared cluster when expected");
46       desired_object = nullptr;
47     }
48     return {std::move(this_sp), desired_object};
49   }
50 
51 private:
ClusterManager()52   ClusterManager() : m_objects() {}
53   // The cluster manager is used primarily to manage the
54   // children of root ValueObjects. So it will always have
55   // one element - the root.  Pointers will often have dynamic
56   // values, so having 2 entries is pretty common.  It's also
57   // pretty common to have small (2,3) structs, so setting the
58   // static size to 4 will cover those cases with no allocations
59   // w/o wasting too much space.
60   llvm::SmallPtrSet<T *, 4> m_objects;
61   std::mutex m_mutex;
62 };
63 
64 } // namespace lldb_private
65 
66 #endif // LLDB_UTILITY_SHAREDCLUSTER_H
67