GCC Code Coverage Report

Directory: cvmfs/
File: cvmfs/kvstore.h
Date: 2025-02-09 02:34:19
Exec Total Coverage
Lines: 23 23 100.0%
Branches: 39 78 50.0%
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1 /**
2 * This file is part of the CernVM File System.
3 */
4
5 #ifndef CVMFS_KVSTORE_H_
6 #define CVMFS_KVSTORE_H_
7
8 #include <pthread.h>
9 #include <unistd.h>
10
11 #include <string>
12 #include <vector>
13
14 #include "cache.h"
15 #include "lru.h"
16 #include "malloc_heap.h"
17 #include "statistics.h"
18 #include "util/async.h"
19 #include "util/single_copy.h"
20
21 using namespace std; // NOLINT
22
23
24 /**
25 * All objects in memory are prepended by an AllocHeader that allows the
26 * Key-Value store to find the pointer when the heap memory manager compacts
27 * the allocations.
28 */
29 struct AllocHeader {
30 254 AllocHeader() : version(0), id() { }
31 uint8_t version;
32 shash::Any id;
33 };
34
35
36 /**
37 * A MmeoryBuffer is used in the staging phase of new objects until they are
38 * committed.
39 */
40 struct MemoryBuffer {
41 306086 MemoryBuffer()
42 306086 : address(NULL)
43 306086 , size(0)
44 306086 , refcount(0)
45 306086 , object_flags(0)
46 306086 , id() {}
47 void *address;
48 size_t size;
49 unsigned int refcount;
50 int object_flags;
51 shash::Any id;
52 };
53
54
55 /**
56 * @p MemoryKvStore provides a simple RAM-backed key/value store suited to
57 * use with @ref RamCacheManager. To insert entries, the caller must allocate
58 * some memory and can choose to set some metadata such as object type.
59 * @p MemoryKvStore takes ownership of the passed-in memory and maintains
60 * reference counts for all its objects. Callers must increment the reference
61 * count on an entry before reading to ensure that the entry is not removed
62 * mid-operation, and decrement the reference count when done. The store
63 * can attempt to reduce its size by removing the least recently used
64 * entries without any outstanding references.
65 */
66 class MemoryKvStore : SingleCopy, public Callbackable<MallocHeap::BlockPtr> {
67 public:
68 enum MemoryAllocator {
69 kMallocLibc,
70 kMallocHeap,
71 };
72
73 struct Counters {
74 perf::Counter *sz_size;
75 perf::Counter *n_getsize;
76 perf::Counter *n_getrefcount;
77 perf::Counter *n_incref;
78 perf::Counter *n_unref;
79 perf::Counter *n_read;
80 perf::Counter *n_commit;
81 perf::Counter *n_delete;
82 perf::Counter *n_shrinkto;
83 perf::Counter *sz_read;
84 perf::Counter *sz_committed;
85 perf::Counter *sz_deleted;
86 perf::Counter *sz_shrunk;
87
88 63 explicit Counters(perf::StatisticsTemplate statistics) {
89
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 63 sz_size = statistics.RegisterTemplated("sz_size", "Total size");
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 63 n_getsize = statistics.RegisterTemplated("n_getsize",
91 "Number of GetSize calls");
92
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 63 n_getrefcount = statistics.RegisterTemplated("n_getrefcount",
93 "Number of GetRefcount calls");
94
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 63 n_incref = statistics.RegisterTemplated("n_incref",
95 "Number of IncRef calls");
96
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 63 n_unref = statistics.RegisterTemplated("n_unref",
97 "Number of Unref calls");
98
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 63 n_read = statistics.RegisterTemplated("n_read", "Number of Read calls");
99
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 63 n_commit = statistics.RegisterTemplated("n_commit",
100 "Number of Commit calls");
101
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 63 n_delete = statistics.RegisterTemplated("n_delete",
102 "Number of Delete calls");
103
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 63 n_shrinkto = statistics.RegisterTemplated("n_shrinkto",
104 "Number of ShrinkTo calls");
105
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 63 sz_read = statistics.RegisterTemplated("sz_read", "Bytes read");
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 63 sz_committed = statistics.RegisterTemplated("sz_committed",
107 "Bytes committed");
108
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 63 sz_deleted = statistics.RegisterTemplated("sz_deleted", "Bytes deleted");
109
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 63 sz_shrunk = statistics.RegisterTemplated("sz_shrunk", "Bytes shrunk");
110 63 }
111 };
112
113 MemoryKvStore(
114 unsigned int cache_entries,
115 MemoryAllocator alloc,
116 unsigned alloc_size,
117 perf::StatisticsTemplate statistics);
118
119 ~MemoryKvStore();
120
121 /**
122 * Check for the existence of an entry
123 * @param id The hash key
124 * @returns True iff the entry exists
125 */
126 bool Contains(const shash::Any &id);
127
128 /**
129 * Get the size in bytes of the entry at id
130 * @param id The hash key
131 * @returns The entry's size
132 * @retval -ENOENT The entry is absent
133 */
134 int64_t GetSize(const shash::Any &id);
135
136 /**
137 * Get the number of references to the entry at id
138 * @param id The hash key
139 * @returns A reference count
140 * @retval -ENOENT The entry is absent
141 */
142 int64_t GetRefcount(const shash::Any &id);
143
144 /**
145 * Increase the reference count on the entry at id
146 * @param id The hash key
147 * @returns True if the entry exists and was updated
148 */
149 bool IncRef(const shash::Any &id);
150
151 /**
152 * Decrease the reference count on the entry at id. If the refcount is zero, no effect
153 * @param id The hash key
154 * @returns True if the entry exists and was updated
155 */
156 bool Unref(const shash::Any &id);
157
158 /**
159 * Copy a portion of the entry at id to the given address. See pread(2)
160 * @param id The hash key
161 * @param buf The address at which to write the data
162 * @param size The number of bytes to copy
163 * @param offset The offset within the entry to start the copy
164 * @returns The number of bytes copied
165 * @retval -ENOENT The entry is absent
166 */
167 int64_t Read(
168 const shash::Any &id,
169 void *buf,
170 size_t size,
171 size_t offset);
172
173 /**
174 * Insert a new memory buffer. The KvStore copies the referred memory, so
175 * callers may free() their buffers after Commit returns
176 * @param buf The memory buffer to insert
177 * @returns -ENFILE if too many file handles are in use
178 * @returns -EIO if memory allocation fails
179 */
180 int Commit(const MemoryBuffer &buf);
181
182 /**
183 * Delete an entry, free()ing its memory. Note that the entry not have any references
184 * @param id The hash key
185 * @returns True iff the entry was successfully deleted
186 */
187 bool Delete(const shash::Any &id);
188
189 /**
190 * Delete the oldest entries until the KvStore uses less than the given size.
191 * Entries with nonzero refcount will not be deleted.
192 * @param size The maximum size to make the KvStore
193 * @returns True iff the shrink succeeds
194 */
195 bool ShrinkTo(size_t size);
196
197 /**
198 * Get the total space used for data
199 */
200 177 size_t GetUsed() { return used_bytes_; }
201
202 private:
203 // Compact memory once utilization falls below the threshold
204 static const double kCompactThreshold; // = 0.8
205
206 bool DoDelete(const shash::Any &id);
207 int DoMalloc(MemoryBuffer *buf);
208 void DoFree(MemoryBuffer *buf);
209 int DoCommit(const MemoryBuffer &buf);
210 void OnBlockMove(const MallocHeap::BlockPtr &ptr);
211 bool CompactMemory();
212
213 MemoryAllocator allocator_;
214 size_t used_bytes_;
215 unsigned int entry_count_;
216 unsigned int max_entries_;
217 lru::LruCache<shash::Any, MemoryBuffer> entries_;
218 MallocHeap *heap_;
219 pthread_rwlock_t rwlock_;
220 Counters counters_;
221 };
222
223 #endif // CVMFS_KVSTORE_H_
224