GCC Code Coverage Report

Directory: cvmfs/
File: cvmfs/kvstore.h
Date: 2025-06-29 02:35:41
Exec Total Coverage
Lines: 19 19 100.0%
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 9962 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 8418814 MemoryBuffer()
42 8418814 : address(NULL), size(0), refcount(0), object_flags(0), id() { }
43 void *address;
44 size_t size;
45 unsigned int refcount;
46 int object_flags;
47 shash::Any id;
48 };
49
50
51 /**
52 * @p MemoryKvStore provides a simple RAM-backed key/value store suited to
53 * use with @ref RamCacheManager. To insert entries, the caller must allocate
54 * some memory and can choose to set some metadata such as object type.
55 * @p MemoryKvStore takes ownership of the passed-in memory and maintains
56 * reference counts for all its objects. Callers must increment the reference
57 * count on an entry before reading to ensure that the entry is not removed
58 * mid-operation, and decrement the reference count when done. The store
59 * can attempt to reduce its size by removing the least recently used
60 * entries without any outstanding references.
61 */
62 class MemoryKvStore : SingleCopy, public Callbackable<MallocHeap::BlockPtr> {
63 public:
64 enum MemoryAllocator {
65 kMallocLibc,
66 kMallocHeap,
67 };
68
69 struct Counters {
70 perf::Counter *sz_size;
71 perf::Counter *n_getsize;
72 perf::Counter *n_getrefcount;
73 perf::Counter *n_incref;
74 perf::Counter *n_unref;
75 perf::Counter *n_read;
76 perf::Counter *n_commit;
77 perf::Counter *n_delete;
78 perf::Counter *n_shrinkto;
79 perf::Counter *sz_read;
80 perf::Counter *sz_committed;
81 perf::Counter *sz_deleted;
82 perf::Counter *sz_shrunk;
83
84 2245 explicit Counters(perf::StatisticsTemplate statistics) {
85
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 2245 sz_size = statistics.RegisterTemplated("sz_size", "Total size");
86
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 2245 n_getsize = statistics.RegisterTemplated("n_getsize",
87 "Number of GetSize calls");
88
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 2245 n_getrefcount = statistics.RegisterTemplated(
89 "n_getrefcount", "Number of GetRefcount calls");
90
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 2245 n_incref = statistics.RegisterTemplated("n_incref",
91 "Number of IncRef calls");
92
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 2245 n_unref = statistics.RegisterTemplated("n_unref",
93 "Number of Unref calls");
94
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 2245 n_read = statistics.RegisterTemplated("n_read", "Number of Read calls");
95
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 2245 n_commit = statistics.RegisterTemplated("n_commit",
96 "Number of Commit calls");
97
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 2245 n_delete = statistics.RegisterTemplated("n_delete",
98 "Number of Delete calls");
99
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 2245 n_shrinkto = statistics.RegisterTemplated("n_shrinkto",
100 "Number of ShrinkTo calls");
101
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 2245 sz_read = statistics.RegisterTemplated("sz_read", "Bytes read");
102
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 2245 sz_committed = statistics.RegisterTemplated("sz_committed",
103 "Bytes committed");
104
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 2245 sz_deleted = statistics.RegisterTemplated("sz_deleted", "Bytes deleted");
105
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 2245 sz_shrunk = statistics.RegisterTemplated("sz_shrunk", "Bytes shrunk");
106 2245 }
107 };
108
109 MemoryKvStore(unsigned int cache_entries,
110 MemoryAllocator alloc,
111 unsigned alloc_size,
112 perf::StatisticsTemplate statistics);
113
114 ~MemoryKvStore();
115
116 /**
117 * Check for the existence of an entry
118 * @param id The hash key
119 * @returns True iff the entry exists
120 */
121 bool Contains(const shash::Any &id);
122
123 /**
124 * Get the size in bytes of the entry at id
125 * @param id The hash key
126 * @returns The entry's size
127 * @retval -ENOENT The entry is absent
128 */
129 int64_t GetSize(const shash::Any &id);
130
131 /**
132 * Get the number of references to the entry at id
133 * @param id The hash key
134 * @returns A reference count
135 * @retval -ENOENT The entry is absent
136 */
137 int64_t GetRefcount(const shash::Any &id);
138
139 /**
140 * Increase the reference count on the entry at id
141 * @param id The hash key
142 * @returns True if the entry exists and was updated
143 */
144 bool IncRef(const shash::Any &id);
145
146 /**
147 * Decrease the reference count on the entry at id. If the refcount is zero,
148 * no effect
149 * @param id The hash key
150 * @returns True if the entry exists and was updated
151 */
152 bool Unref(const shash::Any &id);
153
154 /**
155 * Copy a portion of the entry at id to the given address. See pread(2)
156 * @param id The hash key
157 * @param buf The address at which to write the data
158 * @param size The number of bytes to copy
159 * @param offset The offset within the entry to start the copy
160 * @returns The number of bytes copied
161 * @retval -ENOENT The entry is absent
162 */
163 int64_t Read(const shash::Any &id, void *buf, size_t size, size_t offset);
164
165 /**
166 * Insert a new memory buffer. The KvStore copies the referred memory, so
167 * callers may free() their buffers after Commit returns
168 * @param buf The memory buffer to insert
169 * @returns -ENFILE if too many file handles are in use
170 * @returns -EIO if memory allocation fails
171 */
172 int Commit(const MemoryBuffer &buf);
173
174 /**
175 * Delete an entry, free()ing its memory. Note that the entry not have any
176 * references
177 * @param id The hash key
178 * @returns True iff the entry was successfully deleted
179 */
180 bool Delete(const shash::Any &id);
181
182 /**
183 * Delete the oldest entries until the KvStore uses less than the given size.
184 * Entries with nonzero refcount will not be deleted.
185 * @param size The maximum size to make the KvStore
186 * @returns True iff the shrink succeeds
187 */
188 bool ShrinkTo(size_t size);
189
190 /**
191 * Get the total space used for data
192 */
193 7099 size_t GetUsed() { return used_bytes_; }
194
195 private:
196 // Compact memory once utilization falls below the threshold
197 static const double kCompactThreshold; // = 0.8
198
199 bool DoDelete(const shash::Any &id);
200 int DoMalloc(MemoryBuffer *buf);
201 void DoFree(MemoryBuffer *buf);
202 int DoCommit(const MemoryBuffer &buf);
203 void OnBlockMove(const MallocHeap::BlockPtr &ptr);
204 bool CompactMemory();
205
206 MemoryAllocator allocator_;
207 size_t used_bytes_;
208 unsigned int entry_count_;
209 unsigned int max_entries_;
210 lru::LruCache<shash::Any, MemoryBuffer> entries_;
211 MallocHeap *heap_;
212 pthread_rwlock_t rwlock_;
213 Counters counters_;
214 };
215
216 #endif // CVMFS_KVSTORE_H_
217