1 /*
2  * Copyright (C) 2024 Huawei Device Co., Ltd.
3  * Licensed under the Apache License, Version 2.0 (the "License");
4  * you may not use this file except in compliance with the License.
5  * You may obtain a copy of the License at
6  *
7  *     http://www.apache.org/licenses/LICENSE-2.0
8  *
9  * Unless required by applicable law or agreed to in writing, software
10  * distributed under the License is distributed on an "AS IS" BASIS,
11  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
12  * See the License for the specific language governing permissions and
13  * limitations under the License.
14  */
15 
16 #ifndef DISTRIBUTEDDATAMGR_PASTEBOARD_DEDUPLICATE_MEMORY_H
17 #define DISTRIBUTEDDATAMGR_PASTEBOARD_DEDUPLICATE_MEMORY_H
18 
19 #include <cstdint>
20 #include <list>
21 
22 namespace OHOS {
23 namespace MiscServices {
24 
25 template <typename T>
26 class DeduplicateMemory {
27 public:
28     explicit DeduplicateMemory(int64_t expirationMilliSeconds);
29     ~DeduplicateMemory();
30     bool IsDuplicate(const T &data);
31 
32 private:
33     int64_t GetTimestamp();
34     void ClearExpiration();
35     bool FindExist(const T &data);
36 
37     struct MemoryIdentity {
38         int64_t timestamp;
39         const T data;
40     };
41 
42     std::list<MemoryIdentity> memory_;
43     int64_t expirationMS_;
44 };
45 
46 template <typename T>
DeduplicateMemory(int64_t expirationMilliSeconds)47 DeduplicateMemory<T>::DeduplicateMemory(int64_t expirationMilliSeconds) : expirationMS_(expirationMilliSeconds)
48 {
49 }
50 
51 template <typename T>
~DeduplicateMemory()52 DeduplicateMemory<T>::~DeduplicateMemory()
53 {
54     memory_.clear();
55 }
56 
57 template <typename T>
IsDuplicate(const T &data)58 bool DeduplicateMemory<T>::IsDuplicate(const T &data)
59 {
60     ClearExpiration();
61     if (FindExist(data)) {
62         return true;
63     }
64     int64_t timestamp = GetTimestamp();
65     memory_.push_back(MemoryIdentity({.timestamp = timestamp, .data = data}));
66     return false;
67 }
68 
69 template <typename T>
FindExist(const T &data)70 bool DeduplicateMemory<T>::FindExist(const T &data)
71 {
72     for (const MemoryIdentity &item : memory_) {
73         if (item.data == data) {
74             return true;
75         }
76     }
77     return false;
78 }
79 
80 template <typename T>
GetTimestamp()81 int64_t DeduplicateMemory<T>::GetTimestamp()
82 {
83     return std::chrono::duration_cast<std::chrono::milliseconds>(
84         std::chrono::steady_clock::now().time_since_epoch()).count();
85 }
86 
87 template <typename T>
ClearExpiration()88 void DeduplicateMemory<T>::ClearExpiration()
89 {
90     int64_t timestamp = GetTimestamp();
91     if (timestamp < expirationMS_) {
92         return;
93     }
94     int64_t expirationTimestamp = timestamp - expirationMS_;
95     memory_.remove_if([expirationTimestamp](const MemoryIdentity &identity) {
96         return expirationTimestamp > identity.timestamp;
97     });
98 }
99 } // namespace MiscServices
100 } // namespace OHOS
101 
102 #endif // DISTRIBUTEDDATAMGR_PASTEBOARD_DEDUPLICATE_MEMORY_H
103