1/**
2 * Copyright (c) 2018 Inria
3 * All rights reserved.
4 *
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions are
7 * met: redistributions of source code must retain the above copyright
8 * notice, this list of conditions and the following disclaimer;
9 * redistributions in binary form must reproduce the above copyright
10 * notice, this list of conditions and the following disclaimer in the
11 * documentation and/or other materials provided with the distribution;
12 * neither the name of the copyright holders nor the names of its
13 * contributors may be used to endorse or promote products derived from
14 * this software without specific prior written permission.
15 *
16 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
17 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
18 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
19 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
20 * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
21 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
22 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
23 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
24 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
25 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
26 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
27 *
28 * Authors: Daniel Carvalho
29 */
30
31/**
32 * @file
33 * Declaration of a Second-Chance replacement policy.
34 * The victim is chosen using the timestamp. The oldest entry is chosen
35 * to be evicted, if it hasn't been touched since its insertion. If it
36 * has been touched, it is given a second chance and re-inserted at the
37 * end of the queue.
38 */
39
40#ifndef __MEM_CACHE_REPLACEMENT_POLICIES_SECOND_CHANCE_RP_HH__
41#define __MEM_CACHE_REPLACEMENT_POLICIES_SECOND_CHANCE_RP_HH__
42
| 1/**
2 * Copyright (c) 2018 Inria
3 * All rights reserved.
4 *
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions are
7 * met: redistributions of source code must retain the above copyright
8 * notice, this list of conditions and the following disclaimer;
9 * redistributions in binary form must reproduce the above copyright
10 * notice, this list of conditions and the following disclaimer in the
11 * documentation and/or other materials provided with the distribution;
12 * neither the name of the copyright holders nor the names of its
13 * contributors may be used to endorse or promote products derived from
14 * this software without specific prior written permission.
15 *
16 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
17 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
18 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
19 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
20 * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
21 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
22 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
23 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
24 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
25 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
26 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
27 *
28 * Authors: Daniel Carvalho
29 */
30
31/**
32 * @file
33 * Declaration of a Second-Chance replacement policy.
34 * The victim is chosen using the timestamp. The oldest entry is chosen
35 * to be evicted, if it hasn't been touched since its insertion. If it
36 * has been touched, it is given a second chance and re-inserted at the
37 * end of the queue.
38 */
39
40#ifndef __MEM_CACHE_REPLACEMENT_POLICIES_SECOND_CHANCE_RP_HH__
41#define __MEM_CACHE_REPLACEMENT_POLICIES_SECOND_CHANCE_RP_HH__
42
|
46class SecondChanceRP : public FIFORP
47{
48 protected:
49 /** Second-Chance-specific implementation of replacement data. */
50 struct SecondChanceReplData : public FIFOReplData
51 {
52 /**
53 * This is different from isTouched because isTouched accounts only
54 * for insertion, while this bit is reset every new re-insertion.
55 * @sa SecondChanceRP.
56 */
57 bool hasSecondChance;
58
59 /**
60 * Default constructor.
61 */
62 SecondChanceReplData() : FIFOReplData(), hasSecondChance(false) {}
63 };
64
65 /**
66 * Use replacement data's second chance.
67 *
68 * @param replacement_data Entry that will use its second chance.
69 */
70 void useSecondChance(
71 const std::shared_ptr<SecondChanceReplData>& replacement_data) const;
72
73 public:
74 /** Convenience typedef. */
75 typedef SecondChanceRPParams Params;
76
77 /**
78 * Construct and initiliaze this replacement policy.
79 */
80 SecondChanceRP(const Params *p);
81
82 /**
83 * Destructor.
84 */
85 ~SecondChanceRP() {}
86
87 /**
88 * Invalidate replacement data to set it as the next probable victim.
89 * Invalid entries do not have a second chance, and their last touch tick
90 * is set as the oldest possible.
91 *
92 * @param replacement_data Replacement data to be invalidated.
93 */
94 void invalidate(const std::shared_ptr<ReplacementData>& replacement_data)
95 const override;
96
97 /**
98 * Touch an entry to update its re-insertion tick and second chance bit.
99 *
100 * @param replacement_data Replacement data to be touched.
101 */
102 void touch(const std::shared_ptr<ReplacementData>& replacement_data) const
103 override;
104
105 /**
106 * Reset replacement data. Used when an entry is inserted or re-inserted
107 * in the queue.
108 * Sets its insertion tick and second chance bit.
109 *
110 * @param replacement_data Replacement data to be reset.
111 */
112 void reset(const std::shared_ptr<ReplacementData>& replacement_data) const
113 override;
114
115 /**
116 * Find replacement victim using insertion timestamps and second chance
117 * bit.
118 *
119 * @param cands Replacement candidates, selected by indexing policy.
120 * @return Replacement entry to be replaced.
121 */
122 ReplaceableEntry* getVictim(const ReplacementCandidates& candidates) const
123 override;
124
125 /**
126 * Instantiate a replacement data entry.
127 *
128 * @return A shared pointer to the new replacement data.
129 */
130 std::shared_ptr<ReplacementData> instantiateEntry() override;
131};
132
133#endif // __MEM_CACHE_REPLACEMENT_POLICIES_SECOND_CHANCE_RP_HH__
| 48class SecondChanceRP : public FIFORP
49{
50 protected:
51 /** Second-Chance-specific implementation of replacement data. */
52 struct SecondChanceReplData : public FIFOReplData
53 {
54 /**
55 * This is different from isTouched because isTouched accounts only
56 * for insertion, while this bit is reset every new re-insertion.
57 * @sa SecondChanceRP.
58 */
59 bool hasSecondChance;
60
61 /**
62 * Default constructor.
63 */
64 SecondChanceReplData() : FIFOReplData(), hasSecondChance(false) {}
65 };
66
67 /**
68 * Use replacement data's second chance.
69 *
70 * @param replacement_data Entry that will use its second chance.
71 */
72 void useSecondChance(
73 const std::shared_ptr<SecondChanceReplData>& replacement_data) const;
74
75 public:
76 /** Convenience typedef. */
77 typedef SecondChanceRPParams Params;
78
79 /**
80 * Construct and initiliaze this replacement policy.
81 */
82 SecondChanceRP(const Params *p);
83
84 /**
85 * Destructor.
86 */
87 ~SecondChanceRP() {}
88
89 /**
90 * Invalidate replacement data to set it as the next probable victim.
91 * Invalid entries do not have a second chance, and their last touch tick
92 * is set as the oldest possible.
93 *
94 * @param replacement_data Replacement data to be invalidated.
95 */
96 void invalidate(const std::shared_ptr<ReplacementData>& replacement_data)
97 const override;
98
99 /**
100 * Touch an entry to update its re-insertion tick and second chance bit.
101 *
102 * @param replacement_data Replacement data to be touched.
103 */
104 void touch(const std::shared_ptr<ReplacementData>& replacement_data) const
105 override;
106
107 /**
108 * Reset replacement data. Used when an entry is inserted or re-inserted
109 * in the queue.
110 * Sets its insertion tick and second chance bit.
111 *
112 * @param replacement_data Replacement data to be reset.
113 */
114 void reset(const std::shared_ptr<ReplacementData>& replacement_data) const
115 override;
116
117 /**
118 * Find replacement victim using insertion timestamps and second chance
119 * bit.
120 *
121 * @param cands Replacement candidates, selected by indexing policy.
122 * @return Replacement entry to be replaced.
123 */
124 ReplaceableEntry* getVictim(const ReplacementCandidates& candidates) const
125 override;
126
127 /**
128 * Instantiate a replacement data entry.
129 *
130 * @return A shared pointer to the new replacement data.
131 */
132 std::shared_ptr<ReplacementData> instantiateEntry() override;
133};
134
135#endif // __MEM_CACHE_REPLACEMENT_POLICIES_SECOND_CHANCE_RP_HH__
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