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bbc27441 | 1 | /* |
77b1029d | 2 | * Copyright (C) 1996-2020 The Squid Software Foundation and contributors |
bbc27441 AJ |
3 | * |
4 | * Squid software is distributed under GPLv2+ license and includes | |
5 | * contributions from numerous individuals and organizations. | |
6 | * Please see the COPYING and CONTRIBUTORS files for details. | |
7 | */ | |
8 | ||
44c95fcf AR |
9 | #ifndef SQUID_IPC_STORE_MAP_H |
10 | #define SQUID_IPC_STORE_MAP_H | |
11 | ||
3a8c5551 | 12 | #include "ipc/mem/FlexibleArray.h" |
68353d5a | 13 | #include "ipc/mem/Pointer.h" |
602d9612 | 14 | #include "ipc/ReadWriteLock.h" |
65e41a45 | 15 | #include "sbuf/SBuf.h" |
2745fea5 | 16 | #include "store/forward.h" |
e1ba42a4 | 17 | #include "store_key_md5.h" |
44c95fcf | 18 | |
abf396ec AR |
19 | #include <functional> |
20 | ||
9199139f AR |
21 | namespace Ipc |
22 | { | |
44c95fcf | 23 | |
f13833e9 | 24 | typedef int32_t StoreMapSliceId; |
bc8b6522 AR |
25 | |
26 | /// a piece of Store entry, linked to other pieces, forming a chain | |
ce49546e | 27 | /// slices may be appended by writers while readers read the entry |
bc8b6522 AR |
28 | class StoreMapSlice |
29 | { | |
30 | public: | |
ce49546e | 31 | typedef uint32_t Size; |
bc8b6522 | 32 | |
ce49546e | 33 | StoreMapSlice(): size(0), next(-1) {} |
d2b13bab AJ |
34 | StoreMapSlice(const StoreMapSlice &o) { |
35 | size.exchange(o.size); | |
36 | next.exchange(o.next); | |
37 | } | |
38 | ||
39 | StoreMapSlice &operator =(const StoreMapSlice &o) { | |
40 | size.store(o.size); | |
41 | next.store(o.next); | |
42 | return *this; | |
43 | } | |
44 | ||
c2037547 EB |
45 | /// restore default-constructed state |
46 | void clear() { size = 0; next = -1; } | |
47 | ||
d2b13bab AJ |
48 | std::atomic<Size> size; ///< slice contents size |
49 | std::atomic<StoreMapSliceId> next; ///< ID of the next entry slice | |
bc8b6522 AR |
50 | }; |
51 | ||
50dc81ec AR |
52 | /// Maintains shareable information about a StoreEntry as a whole. |
53 | /// An anchor points to one or more StoreEntry slices. This is the | |
54 | /// only lockable part of shared StoreEntry information, providing | |
55 | /// protection for all StoreEntry slices. | |
56 | class StoreMapAnchor | |
9199139f | 57 | { |
44c95fcf | 58 | public: |
50dc81ec | 59 | StoreMapAnchor(); |
44c95fcf | 60 | |
50dc81ec | 61 | /// store StoreEntry key and basics for an inode slot |
4310f8b0 EB |
62 | void set(const StoreEntry &anEntry, const cache_key *aKey = nullptr); |
63 | /// load StoreEntry basics that were previously stored with set() | |
64 | void exportInto(StoreEntry &) const; | |
44c95fcf AR |
65 | |
66 | void setKey(const cache_key *const aKey); | |
67 | bool sameKey(const cache_key *const aKey) const; | |
68 | ||
50dc81ec AR |
69 | /// undo the effects of set(), setKey(), etc., but keep locks and state |
70 | void rewind(); | |
71 | ||
ce49546e AR |
72 | /* entry state may change immediately after calling these methods unless |
73 | * the caller holds an appropriate lock */ | |
74 | bool empty() const { return !key[0] && !key[1]; } | |
75 | bool reading() const { return lock.readers; } | |
a3023c03 | 76 | bool writing() const { return lock.writing; } |
ce49546e AR |
77 | bool complete() const { return !empty() && !writing(); } |
78 | ||
44c95fcf AR |
79 | public: |
80 | mutable ReadWriteLock lock; ///< protects slot data below | |
d2b13bab | 81 | std::atomic<uint8_t> waitingToBeFreed; ///< may be accessed w/o a lock |
4310f8b0 EB |
82 | /// whether StoreMap::abortWriting() was called for a read-locked entry |
83 | std::atomic<uint8_t> writerHalted; | |
44c95fcf | 84 | |
ce49546e | 85 | // fields marked with [app] can be modified when appending-while-reading |
abf396ec | 86 | // fields marked with [update] can be modified when updating-while-reading |
ce49546e | 87 | |
b56b37cf | 88 | uint64_t key[2] = {0, 0}; ///< StoreEntry key |
44c95fcf AR |
89 | |
90 | // STORE_META_STD TLV field from StoreEntry | |
91 | struct Basics { | |
b56b37cf AJ |
92 | void clear() { |
93 | timestamp = 0; | |
94 | lastref = 0; | |
95 | expires = 0; | |
96 | lastmod = 0; | |
97 | swap_file_sz.store(0); | |
98 | refcount = 0; | |
99 | flags = 0; | |
100 | } | |
101 | time_t timestamp = 0; | |
102 | time_t lastref = 0; | |
103 | time_t expires = 0; | |
104 | time_t lastmod = 0; | |
d2b13bab | 105 | std::atomic<uint64_t> swap_file_sz; // [app] |
b56b37cf AJ |
106 | uint16_t refcount = 0; |
107 | uint16_t flags = 0; | |
9199139f | 108 | } basics; |
44c95fcf | 109 | |
e6d2c263 | 110 | /// where the chain of StoreEntry slices begins [app] |
d2b13bab | 111 | std::atomic<StoreMapSliceId> start; |
abf396ec AR |
112 | |
113 | /// where the updated chain prefix containing metadata/headers ends [update] | |
114 | /// if unset, this anchor points to a chain that was never updated | |
115 | std::atomic<StoreMapSliceId> splicingPoint; | |
1860fbac AR |
116 | }; |
117 | ||
118 | /// an array of shareable Items | |
119 | /// must be the last data member or, if used as a parent class, the last parent | |
120 | template <class C> | |
121 | class StoreMapItems | |
122 | { | |
123 | public: | |
124 | typedef C Item; | |
125 | typedef Ipc::Mem::Owner< StoreMapItems<Item> > Owner; | |
126 | ||
127 | explicit StoreMapItems(const int aCapacity): capacity(aCapacity), items(aCapacity) {} | |
50dc81ec | 128 | |
1860fbac AR |
129 | size_t sharedMemorySize() const { return SharedMemorySize(capacity); } |
130 | static size_t SharedMemorySize(const int aCapacity) { return sizeof(StoreMapItems<Item>) + aCapacity*sizeof(Item); } | |
131 | ||
132 | const int capacity; ///< total number of items | |
133 | Ipc::Mem::FlexibleArray<Item> items; ///< storage | |
44c95fcf AR |
134 | }; |
135 | ||
1860fbac AR |
136 | /// StoreMapSlices indexed by their slice ID. |
137 | typedef StoreMapItems<StoreMapSlice> StoreMapSlices; | |
138 | ||
abf396ec | 139 | /// StoreMapAnchors (indexed by fileno) plus |
1860fbac AR |
140 | /// sharing-safe basic housekeeping info about Store entries |
141 | class StoreMapAnchors | |
9d4e9cfb | 142 | { |
50dc81ec | 143 | public: |
1860fbac AR |
144 | typedef Ipc::Mem::Owner< StoreMapAnchors > Owner; |
145 | ||
146 | explicit StoreMapAnchors(const int aCapacity); | |
147 | ||
148 | size_t sharedMemorySize() const; | |
149 | static size_t SharedMemorySize(const int anAnchorLimit); | |
150 | ||
d2b13bab AJ |
151 | std::atomic<int32_t> count; ///< current number of entries |
152 | std::atomic<uint32_t> victim; ///< starting point for purge search | |
1860fbac AR |
153 | const int capacity; ///< total number of anchors |
154 | Ipc::Mem::FlexibleArray<StoreMapAnchor> items; ///< anchors storage | |
50dc81ec | 155 | }; |
1860fbac | 156 | // TODO: Find an elegant way to use StoreMapItems in StoreMapAnchors |
50dc81ec | 157 | |
abf396ec AR |
158 | /// StoreMapAnchor positions, indexed by entry "name" (i.e., the entry key hash) |
159 | typedef StoreMapItems< std::atomic<sfileno> > StoreMapFileNos; | |
160 | ||
161 | /// Aggregates information required for updating entry metadata and headers. | |
162 | class StoreMapUpdate | |
163 | { | |
164 | public: | |
165 | /// During an update, the stored entry has two editions: stale and fresh. | |
166 | class Edition | |
167 | { | |
168 | public: | |
169 | Edition(): anchor(nullptr), fileNo(-1), name(-1), splicingPoint(-1) {} | |
170 | ||
171 | /// whether this entry edition is currently used/initialized | |
172 | explicit operator bool() const { return anchor; } | |
173 | ||
174 | StoreMapAnchor *anchor; ///< StoreMap::anchors[fileNo], for convenience/speed | |
175 | sfileno fileNo; ///< StoreMap::fileNos[name], for convenience/speed | |
176 | sfileno name; ///< StoreEntry position in StoreMap::fileNos, for swapping Editions | |
177 | ||
178 | /// the last slice in the chain still containing metadata/headers | |
179 | StoreMapSliceId splicingPoint; | |
180 | }; | |
181 | ||
182 | explicit StoreMapUpdate(StoreEntry *anEntry); | |
183 | StoreMapUpdate(const StoreMapUpdate &other); | |
184 | ~StoreMapUpdate(); | |
185 | ||
186 | StoreMapUpdate &operator =(const StoreMapUpdate &other) = delete; | |
187 | ||
188 | StoreEntry *entry; ///< the store entry being updated | |
66d51f4f AR |
189 | Edition stale; ///< old anchor and chain |
190 | Edition fresh; ///< new anchor and the updated chain prefix | |
abf396ec AR |
191 | }; |
192 | ||
7f6748c8 AR |
193 | class StoreMapCleaner; |
194 | ||
1860fbac | 195 | /// Manages shared Store index (e.g., locking/unlocking/freeing entries) using |
abf396ec AR |
196 | /// StoreMapFileNos indexed by hashed entry keys (a.k.a. entry names), |
197 | /// StoreMapAnchors indexed by fileno, and | |
198 | /// StoreMapSlices indexed by slice ID. | |
44c95fcf AR |
199 | class StoreMap |
200 | { | |
201 | public: | |
abf396ec | 202 | typedef StoreMapFileNos FileNos; |
50dc81ec | 203 | typedef StoreMapAnchor Anchor; |
1860fbac | 204 | typedef StoreMapAnchors Anchors; |
50dc81ec AR |
205 | typedef sfileno AnchorId; |
206 | typedef StoreMapSlice Slice; | |
1860fbac | 207 | typedef StoreMapSlices Slices; |
50dc81ec | 208 | typedef StoreMapSliceId SliceId; |
abf396ec | 209 | typedef StoreMapUpdate Update; |
44c95fcf | 210 | |
1860fbac AR |
211 | public: |
212 | /// aggregates anchor and slice owners for Init() caller convenience | |
2da4bfe6 A |
213 | class Owner |
214 | { | |
f8f98441 | 215 | public: |
1860fbac AR |
216 | Owner(); |
217 | ~Owner(); | |
abf396ec | 218 | FileNos::Owner *fileNos; |
1860fbac AR |
219 | Anchors::Owner *anchors; |
220 | Slices::Owner *slices; | |
221 | private: | |
222 | Owner(const Owner &); // not implemented | |
223 | Owner &operator =(const Owner &); // not implemented | |
68353d5a DK |
224 | }; |
225 | ||
68353d5a | 226 | /// initialize shared memory |
1860fbac | 227 | static Owner *Init(const SBuf &path, const int slotLimit); |
68353d5a | 228 | |
1860fbac | 229 | StoreMap(const SBuf &aPath); |
44c95fcf | 230 | |
abf396ec AR |
231 | /// computes map entry anchor position for a given entry key |
232 | sfileno fileNoByKey(const cache_key *const key) const; | |
50dc81ec AR |
233 | |
234 | /// Like strcmp(mapped, new), but for store entry versions/timestamps. | |
235 | /// Returns +2 if the mapped entry does not exist; -1/0/+1 otherwise. | |
236 | /// Comparison may be inaccurate unless the caller is a lock holder. | |
237 | int compareVersions(const sfileno oldFileno, time_t newVersion) const; | |
238 | ||
239 | /// finds, locks, and returns an anchor for an empty key position, | |
240 | /// erasing the old entry (if any) | |
241 | Anchor *openForWriting(const cache_key *const key, sfileno &fileno); | |
242 | /// locks and returns an anchor for the empty fileno position; if | |
243 | /// overwriteExisting is false and the position is not empty, returns nil | |
244 | Anchor *openForWritingAt(sfileno fileno, bool overwriteExisting = true); | |
ce49546e AR |
245 | /// restrict opened for writing entry to appending operations; allow reads |
246 | void startAppending(const sfileno fileno); | |
50dc81ec | 247 | /// successfully finish creating or updating the entry at fileno pos |
8253d451 AR |
248 | void closeForWriting(const sfileno fileno); |
249 | /// stop writing (or updating) the locked entry and start reading it | |
250 | void switchWritingToReading(const sfileno fileno); | |
50dc81ec AR |
251 | /// unlock and "forget" openForWriting entry, making it Empty again |
252 | /// this call does not free entry slices so the caller has to do that | |
253 | void forgetWritingEntry(const sfileno fileno); | |
254 | ||
abf396ec AR |
255 | /// finds and locks the Update entry for an exclusive metadata update |
256 | bool openForUpdating(Update &update, sfileno fileNoHint); | |
257 | /// makes updated info available to others, unlocks, and cleans up | |
258 | void closeForUpdating(Update &update); | |
259 | /// undoes partial update, unlocks, and cleans up | |
260 | void abortUpdating(Update &update); | |
261 | ||
d1d3b4dc EB |
262 | /// the caller must hold a lock on the entry |
263 | /// \returns nullptr unless the slice is readable | |
50dc81ec AR |
264 | const Anchor *peekAtReader(const sfileno fileno) const; |
265 | ||
d1d3b4dc EB |
266 | /// the caller must hold a lock on the entry |
267 | /// \returns nullptr unless the slice is writeable | |
268 | const Anchor *peekAtWriter(const sfileno fileno) const; | |
269 | ||
270 | /// the caller must hold a lock on the entry | |
271 | /// \returns the corresponding Anchor | |
d366a7fa AR |
272 | const Anchor &peekAtEntry(const sfileno fileno) const; |
273 | ||
ce49546e | 274 | /// free the entry if possible or mark it as waiting to be freed if not |
4310f8b0 EB |
275 | /// \returns whether the entry was neither empty nor marked |
276 | bool freeEntry(const sfileno); | |
ce49546e AR |
277 | /// free the entry if possible or mark it as waiting to be freed if not |
278 | /// does nothing if we cannot check that the key matches the cached entry | |
279 | void freeEntryByKey(const cache_key *const key); | |
50dc81ec | 280 | |
4310f8b0 EB |
281 | /// whether the entry with the given key exists and was marked as |
282 | /// "waiting to be freed" some time ago | |
283 | bool markedForDeletion(const cache_key *const); | |
284 | ||
285 | /// whether the index contains a valid readable entry with the given key | |
286 | bool hasReadableEntry(const cache_key *const); | |
287 | ||
50dc81ec AR |
288 | /// opens entry (identified by key) for reading, increments read level |
289 | const Anchor *openForReading(const cache_key *const key, sfileno &fileno); | |
290 | /// opens entry (identified by sfileno) for reading, increments read level | |
b2aca62a | 291 | const Anchor *openForReadingAt(const sfileno, const cache_key *const); |
50dc81ec AR |
292 | /// closes open entry after reading, decrements read level |
293 | void closeForReading(const sfileno fileno); | |
d1d3b4dc EB |
294 | /// same as closeForReading() but also frees the entry if it is unlocked |
295 | void closeForReadingAndFreeIdle(const sfileno fileno); | |
44c95fcf | 296 | |
5bd8ce13 AR |
297 | /// openForReading() but creates a new entry if there is no old one |
298 | const Anchor *openOrCreateForReading(const cache_key *, sfileno &, const StoreEntry &); | |
299 | ||
50dc81ec AR |
300 | /// writeable slice within an entry chain created by openForWriting() |
301 | Slice &writeableSlice(const AnchorId anchorId, const SliceId sliceId); | |
302 | /// readable slice within an entry chain opened by openForReading() | |
303 | const Slice &readableSlice(const AnchorId anchorId, const SliceId sliceId) const; | |
304 | /// writeable anchor for the entry created by openForWriting() | |
305 | Anchor &writeableEntry(const AnchorId anchorId); | |
ce49546e AR |
306 | /// readable anchor for the entry created by openForReading() |
307 | const Anchor &readableEntry(const AnchorId anchorId) const; | |
44c95fcf | 308 | |
c2037547 EB |
309 | /// prepare a chain-unaffiliated slice for being added to an entry chain |
310 | void prepFreeSlice(const SliceId sliceId); | |
311 | ||
abf396ec AR |
312 | /// Returns the ID of the entry slice containing n-th byte or |
313 | /// a negative ID if the entry does not store that many bytes (yet). | |
314 | /// Requires a read lock. | |
315 | SliceId sliceContaining(const sfileno fileno, const uint64_t nth) const; | |
316 | ||
a3023c03 AR |
317 | /// stop writing the entry, freeing its slot for others to use if possible |
318 | void abortWriting(const sfileno fileno); | |
44c95fcf | 319 | |
5bba33c9 | 320 | /// either finds and frees an entry with at least 1 slice or returns false |
50dc81ec | 321 | bool purgeOne(); |
44c95fcf | 322 | |
b2aca62a EB |
323 | /// validates locked hit metadata and calls freeEntry() for invalid entries |
324 | /// \returns whether hit metadata is correct | |
325 | bool validateHit(const sfileno); | |
326 | ||
327 | void disableHitValidation() { hitValidation = false; } | |
328 | ||
50dc81ec AR |
329 | /// copies slice to its designated position |
330 | void importSlice(const SliceId sliceId, const Slice &slice); | |
44c95fcf | 331 | |
36c84e19 AR |
332 | /* SwapFilenMax limits the number of entries, but not slices or slots */ |
333 | bool validEntry(const int n) const; ///< whether n is a valid slice coordinate | |
334 | bool validSlice(const int n) const; ///< whether n is a valid slice coordinate | |
50dc81ec AR |
335 | int entryCount() const; ///< number of writeable and readable entries |
336 | int entryLimit() const; ///< maximum entryCount() possible | |
36c84e19 | 337 | int sliceLimit() const; ///< maximum number of slices possible |
44c95fcf AR |
338 | |
339 | /// adds approximate current stats to the supplied ones | |
340 | void updateStats(ReadWriteLockStats &stats) const; | |
341 | ||
7f6748c8 AR |
342 | StoreMapCleaner *cleaner; ///< notified before a readable entry is freed |
343 | ||
44c95fcf | 344 | protected: |
1860fbac | 345 | const SBuf path; ///< cache_dir path or similar cache name; for logging |
abf396ec | 346 | Mem::Pointer<StoreMapFileNos> fileNos; ///< entry inodes (starting blocks) |
1860fbac AR |
347 | Mem::Pointer<StoreMapAnchors> anchors; ///< entry inodes (starting blocks) |
348 | Mem::Pointer<StoreMapSlices> slices; ///< chained entry pieces positions | |
44c95fcf AR |
349 | |
350 | private: | |
abf396ec AR |
351 | /// computes entry name (i.e., key hash) for a given entry key |
352 | sfileno nameByKey(const cache_key *const key) const; | |
353 | /// computes anchor position for a given entry name | |
354 | sfileno fileNoByName(const sfileno name) const; | |
355 | void relocate(const sfileno name, const sfileno fileno); | |
356 | ||
1860fbac AR |
357 | Anchor &anchorAt(const sfileno fileno); |
358 | const Anchor &anchorAt(const sfileno fileno) const; | |
50dc81ec | 359 | Anchor &anchorByKey(const cache_key *const key); |
44c95fcf | 360 | |
1860fbac AR |
361 | Slice &sliceAt(const SliceId sliceId); |
362 | const Slice &sliceAt(const SliceId sliceId) const; | |
50dc81ec | 363 | Anchor *openForReading(Slice &s); |
abf396ec AR |
364 | bool openKeyless(Update::Edition &edition); |
365 | void closeForUpdateFinal(Update &update); | |
366 | ||
367 | typedef std::function<bool (const sfileno name)> NameFilter; // a "name"-based test | |
368 | bool visitVictims(const NameFilter filter); | |
50dc81ec AR |
369 | |
370 | void freeChain(const sfileno fileno, Anchor &inode, const bool keepLock); | |
abf396ec | 371 | void freeChainAt(SliceId sliceId, const SliceId splicingPoint); |
b2aca62a EB |
372 | |
373 | /// whether paranoid_hit_validation should be performed | |
374 | bool hitValidation; | |
68353d5a | 375 | }; |
44c95fcf | 376 | |
50dc81ec | 377 | /// API for adjusting external state when dirty map slice is being freed |
7f6748c8 AR |
378 | class StoreMapCleaner |
379 | { | |
380 | public: | |
381 | virtual ~StoreMapCleaner() {} | |
382 | ||
50dc81ec | 383 | /// adjust slice-linked state before a locked Readable slice is erased |
36c84e19 | 384 | virtual void noteFreeMapSlice(const StoreMapSliceId sliceId) = 0; |
7f6748c8 AR |
385 | }; |
386 | ||
44c95fcf AR |
387 | } // namespace Ipc |
388 | ||
75f8f9a2 | 389 | // We do not reuse FileMap because we cannot control its size, |
44c95fcf AR |
390 | // resulting in sfilenos that are pointing beyond the database. |
391 | ||
392 | #endif /* SQUID_IPC_STORE_MAP_H */ | |
f53969cc | 393 |