StoreMap.h
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1 /*
2  * Copyright (C) 1996-2020 The Squid Software Foundation and contributors
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 
9 #ifndef SQUID_IPC_STORE_MAP_H
10 #define SQUID_IPC_STORE_MAP_H
11 
12 #include "ipc/mem/FlexibleArray.h"
13 #include "ipc/mem/Pointer.h"
14 #include "ipc/ReadWriteLock.h"
15 #include "sbuf/SBuf.h"
16 #include "store/forward.h"
17 #include "store_key_md5.h"
18 
19 #include <functional>
20 
21 namespace Ipc
22 {
23 
24 typedef int32_t StoreMapSliceId;
25 
29 {
30 public:
31  typedef uint32_t Size;
32 
33  StoreMapSlice(): size(0), next(-1) {}
35  size.exchange(o.size);
36  next.exchange(o.next);
37  }
38 
40  size.store(o.size);
41  next.store(o.next);
42  return *this;
43  }
44 
46  void clear() { size = 0; next = -1; }
47 
48  std::atomic<Size> size;
49  std::atomic<StoreMapSliceId> next;
50 };
51 
57 {
58 public:
60 
62  void set(const StoreEntry &anEntry, const cache_key *aKey = nullptr);
64  void exportInto(StoreEntry &) const;
65 
66  void setKey(const cache_key *const aKey);
67  bool sameKey(const cache_key *const aKey) const;
68 
70  void rewind();
71 
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; }
76  bool writing() const { return lock.writing; }
77  bool complete() const { return !empty() && !writing(); }
78 
79 public:
80  mutable ReadWriteLock lock;
81  std::atomic<uint8_t> waitingToBeFreed;
82  std::atomic<uint8_t> writerHalted;
84 
85  // fields marked with [app] can be modified when appending-while-reading
86  // fields marked with [update] can be modified when updating-while-reading
87 
88  uint64_t key[2] = {0, 0};
89 
90  // STORE_META_STD TLV field from StoreEntry
91  struct Basics {
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;
105  std::atomic<uint64_t> swap_file_sz; // [app]
106  uint16_t refcount = 0;
107  uint16_t flags = 0;
108  } basics;
109 
111  std::atomic<StoreMapSliceId> start;
112 
115  std::atomic<StoreMapSliceId> splicingPoint;
116 };
117 
120 template <class C>
122 {
123 public:
124  typedef C Item;
126 
127  explicit StoreMapItems(const int aCapacity): capacity(aCapacity), items(aCapacity) {}
128 
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  Item &at(const int index)
133  {
134  assert(index >= 0);
135  assert(index < capacity);
136  return items[index];
137  }
138 
139  const Item &at(const int index) const
140  {
141  return const_cast<StoreMapItems<C>&>(*this).at(index);
142  }
143 
145  void fill(const Item &value)
146  {
147  for (int index = 0; index < capacity; ++index)
148  items[index] = value;
149  }
150 
151  const int capacity;
153 };
154 
157 
161 {
162 public:
164 
165  explicit StoreMapAnchors(const int aCapacity);
166 
167  size_t sharedMemorySize() const;
168  static size_t SharedMemorySize(const int anAnchorLimit);
169 
170  std::atomic<int32_t> count;
171  std::atomic<uint32_t> victim;
172  const int capacity;
174 };
175 // TODO: Find an elegant way to use StoreMapItems in StoreMapAnchors
176 
179 
182 {
183 public:
185  class Edition
186  {
187  public:
188  Edition(): anchor(nullptr), fileNo(-1), name(-1), splicingPoint(-1) {}
189 
191  explicit operator bool() const { return anchor; }
192 
196 
199  };
200 
201  explicit StoreMapUpdate(StoreEntry *anEntry);
202  StoreMapUpdate(const StoreMapUpdate &other);
203  ~StoreMapUpdate();
204 
205  StoreMapUpdate &operator =(const StoreMapUpdate &other) = delete;
206 
210 };
211 
212 class StoreMapCleaner;
213 
218 class StoreMap
219 {
220 public:
224  typedef sfileno AnchorId;
229 
230 public:
232  class Owner
233  {
234  public:
235  Owner();
236  ~Owner();
240  private:
241  Owner(const Owner &); // not implemented
242  Owner &operator =(const Owner &); // not implemented
243  };
244 
246  static Owner *Init(const SBuf &path, const int slotLimit);
247 
248  StoreMap(const SBuf &aPath);
249 
251  sfileno fileNoByKey(const cache_key *const key) const;
252 
256  int compareVersions(const sfileno oldFileno, time_t newVersion) const;
257 
260  Anchor *openForWriting(const cache_key *const key, sfileno &fileno);
263  Anchor *openForWritingAt(sfileno fileno, bool overwriteExisting = true);
265  void startAppending(const sfileno fileno);
267  void closeForWriting(const sfileno fileno);
269  void switchWritingToReading(const sfileno fileno);
272  void forgetWritingEntry(const sfileno fileno);
273 
275  bool openForUpdating(Update &update, sfileno fileNoHint);
277  void closeForUpdating(Update &update);
279  void abortUpdating(Update &update);
280 
283  const Anchor *peekAtReader(const sfileno fileno) const;
284 
287  const Anchor *peekAtWriter(const sfileno fileno) const;
288 
291  const Anchor &peekAtEntry(const sfileno fileno) const;
292 
295  bool freeEntry(const sfileno);
298  void freeEntryByKey(const cache_key *const key);
299 
302  bool markedForDeletion(const cache_key *const);
303 
305  bool hasReadableEntry(const cache_key *const);
306 
308  const Anchor *openForReading(const cache_key *const key, sfileno &fileno);
310  const Anchor *openForReadingAt(const sfileno, const cache_key *const);
312  void closeForReading(const sfileno fileno);
314  void closeForReadingAndFreeIdle(const sfileno fileno);
315 
317  const Anchor *openOrCreateForReading(const cache_key *, sfileno &, const StoreEntry &);
318 
320  Slice &writeableSlice(const AnchorId anchorId, const SliceId sliceId);
322  const Slice &readableSlice(const AnchorId anchorId, const SliceId sliceId) const;
324  Anchor &writeableEntry(const AnchorId anchorId);
326  const Anchor &readableEntry(const AnchorId anchorId) const;
327 
329  void prepFreeSlice(const SliceId sliceId);
330 
334  SliceId sliceContaining(const sfileno fileno, const uint64_t nth) const;
335 
337  void abortWriting(const sfileno fileno);
338 
340  bool purgeOne();
341 
344  bool validateHit(const sfileno);
345 
347 
349  void importSlice(const SliceId sliceId, const Slice &slice);
350 
351  /* SwapFilenMax limits the number of entries, but not slices or slots */
352  bool validEntry(const int n) const;
353  bool validSlice(const int n) const;
354  int entryCount() const;
355  int entryLimit() const;
356  int sliceLimit() const;
357 
359  void updateStats(ReadWriteLockStats &stats) const;
360 
362 
363 protected:
364  const SBuf path;
368 
369 private:
371  sfileno nameByKey(const cache_key *const key) const;
373  sfileno fileNoByName(const sfileno name) const;
374  void relocate(const sfileno name, const sfileno fileno);
375 
376  Anchor &anchorAt(const sfileno fileno);
377  const Anchor &anchorAt(const sfileno fileno) const;
378  Anchor &anchorByKey(const cache_key *const key);
379 
380  Slice &sliceAt(const SliceId sliceId);
381  const Slice &sliceAt(const SliceId sliceId) const;
383  bool openKeyless(Update::Edition &edition);
384  void closeForUpdateFinal(Update &update);
385 
386  typedef std::function<bool (const sfileno name)> NameFilter; // a "name"-based test
387  bool visitVictims(const NameFilter filter);
388 
389  void freeChain(const sfileno fileno, Anchor &inode, const bool keepLock);
390  void freeChainAt(SliceId sliceId, const SliceId splicingPoint);
391 
394 };
395 
398 {
399 public:
400  virtual ~StoreMapCleaner() {}
401 
403  virtual void noteFreeMapSlice(const StoreMapSliceId sliceId) = 0;
404 };
405 
406 } // namespace Ipc
407 
408 // We do not reuse FileMap because we cannot control its size,
409 // resulting in sfilenos that are pointing beyond the database.
410 
411 #endif /* SQUID_IPC_STORE_MAP_H */
412 
Ipc::Mem::FlexibleArray< Item > items
storage
Definition: StoreMap.h:152
Anchor & writeableEntry(const AnchorId anchorId)
writeable anchor for the entry created by openForWriting()
Definition: StoreMap.cc:237
void freeEntryByKey(const cache_key *const key)
Definition: StoreMap.cc:331
bool empty() const
Definition: StoreMap.h:74
class Ping::pingStats_ stats
std::atomic< int32_t > count
current number of entries
Definition: StoreMap.h:170
approximate stats of a set of ReadWriteLocks
Definition: ReadWriteLock.h:63
void closeForWriting(const sfileno fileno)
successfully finish creating or updating the entry at fileno pos
Definition: StoreMap.cc:200
size_t sharedMemorySize() const
Definition: StoreMap.h:129
void startAppending(const sfileno fileno)
restrict opened for writing entry to appending operations; allow reads
Definition: StoreMap.cc:191
std::atomic< bool > writing
there is a writing user (there can be at most 1)
Definition: ReadWriteLock.h:50
void importSlice(const SliceId sliceId, const Slice &slice)
copies slice to its designated position
Definition: StoreMap.cc:722
unsigned char cache_key
Store key.
Definition: forward.h:29
StoreMap(const SBuf &aPath)
Definition: StoreMap.cc:54
bool sameKey(const cache_key *const aKey) const
Definition: StoreMap.cc:952
void relocate(const sfileno name, const sfileno fileno)
map name to fileNo
Definition: StoreMap.cc:905
Definition: SBuf.h:86
virtual ~StoreMapCleaner()
Definition: StoreMap.h:400
size_t sharedMemorySize() const
Definition: StoreMap.cc:1057
StoreMapSlice & operator=(const StoreMapSlice &o)
Definition: StoreMap.h:39
void set(const StoreEntry &anEntry, const cache_key *aKey=nullptr)
store StoreEntry key and basics for an inode slot
Definition: StoreMap.cc:959
Edition fresh
new anchor and the updated chain prefix
Definition: StoreMap.h:209
void forgetWritingEntry(const sfileno fileno)
Definition: StoreMap.cc:84
const Anchor * peekAtReader(const sfileno fileno) const
Definition: StoreMap.cc:287
SliceId sliceContaining(const sfileno fileno, const uint64_t nth) const
Definition: StoreMap.cc:421
bool writing() const
Definition: StoreMap.h:76
Mem::Pointer< StoreMapAnchors > anchors
entry inodes (starting blocks)
Definition: StoreMap.h:366
ReadWriteLock lock
protects slot data below
Definition: StoreMap.h:80
const Anchor * openForReadingAt(const sfileno, const cache_key *const)
opens entry (identified by sfileno) for reading, increments read level
Definition: StoreMap.cc:453
void freeChain(const sfileno fileno, Anchor &inode, const bool keepLock)
unconditionally frees an already locked chain of slots, unlocking if needed
Definition: StoreMap.cc:375
bool validEntry(const int n) const
whether n is a valid slice coordinate
Definition: StoreMap.cc:758
StoreMapItems< std::atomic< sfileno > > StoreMapFileNos
StoreMapAnchor positions, indexed by entry "name" (i.e., the entry key hash)
Definition: StoreMap.h:178
const int capacity
total number of items
Definition: StoreMap.h:151
Anchor & anchorAt(const sfileno fileno)
Definition: StoreMap.cc:871
void updateStats(ReadWriteLockStats &stats) const
adds approximate current stats to the supplied ones
Definition: StoreMap.cc:751
std::atomic< uint32_t > readers
number of reading users
Definition: ReadWriteLock.h:49
uint64_t key[2]
StoreEntry key.
Definition: StoreMap.h:88
void prepFreeSlice(const SliceId sliceId)
prepare a chain-unaffiliated slice for being added to an entry chain
Definition: StoreMap.cc:413
StoreMapUpdate Update
Definition: StoreMap.h:228
StoreMapItems< StoreMapSlice > StoreMapSlices
StoreMapSlices indexed by their slice ID.
Definition: StoreMap.h:156
Mem::Pointer< StoreMapSlices > slices
chained entry pieces positions
Definition: StoreMap.h:367
static size_t SharedMemorySize(const int anAnchorLimit)
Definition: StoreMap.cc:1063
static Owner * Init(const SBuf &path, const int slotLimit)
initialize shared memory
Definition: StoreMap.cc:42
Mem::Pointer< StoreMapFileNos > fileNos
entry inodes (starting blocks)
Definition: StoreMap.h:365
std::atomic< uint8_t > writerHalted
whether StoreMap::abortWriting() was called for a read-locked entry
Definition: StoreMap.h:83
std::atomic< StoreMapSliceId > start
where the chain of StoreEntry slices begins [app]
Definition: StoreMap.h:111
StoreMapUpdate(StoreEntry *anEntry)
Definition: StoreMap.cc:1011
std::atomic< StoreMapSliceId > splicingPoint
Definition: StoreMap.h:115
void closeForUpdating(Update &update)
makes updated info available to others, unlocks, and cleans up
Definition: StoreMap.cc:605
Ipc::Mem::FlexibleArray< StoreMapAnchor > items
anchors storage
Definition: StoreMap.h:173
Owner & operator=(const Owner &)
const Anchor * openForReading(const cache_key *const key, sfileno &fileno)
opens entry (identified by key) for reading, increments read level
Definition: StoreMap.cc:440
std::atomic< StoreMapSliceId > next
ID of the next entry slice.
Definition: StoreMap.h:49
struct Ipc::StoreMapAnchor::Basics basics
Ipc::Mem::Owner< StoreMapAnchors > Owner
Definition: StoreMap.h:163
const Anchor & readableEntry(const AnchorId anchorId) const
readable anchor for the entry created by openForReading()
Definition: StoreMap.cc:244
StoreMapAnchors Anchors
Definition: StoreMap.h:223
sfileno AnchorId
Definition: StoreMap.h:224
int entryLimit() const
maximum entryCount() possible
Definition: StoreMap.cc:733
int32_t StoreMapSliceId
Definition: StoreMap.h:24
Edition stale
old anchor and chain
Definition: StoreMap.h:208
StoreMapUpdate & operator=(const StoreMapUpdate &other)=delete
bool openKeyless(Update::Edition &edition)
Definition: StoreMap.cc:587
int sliceLimit() const
maximum number of slices possible
Definition: StoreMap.cc:745
FileNos::Owner * fileNos
Definition: StoreMap.h:237
Ipc::Mem::Owner< StoreMapItems< Item > > Owner
Definition: StoreMap.h:125
bool validateHit(const sfileno)
Definition: StoreMap.cc:801
void closeForReading(const sfileno fileno)
closes open entry after reading, decrements read level
Definition: StoreMap.cc:497
API for adjusting external state when dirty map slice is being freed.
Definition: StoreMap.h:397
StoreEntry * entry
the store entry being updated
Definition: StoreMap.h:207
void setKey(const cache_key *const aKey)
Definition: StoreMap.cc:945
bool validSlice(const int n) const
whether n is a valid slice coordinate
Definition: StoreMap.cc:764
StoreMapSlice(const StoreMapSlice &o)
Definition: StoreMap.h:34
void rewind()
undo the effects of set(), setKey(), etc., but keep locks and state
Definition: StoreMap.cc:997
const SBuf path
cache_dir path or similar cache name; for logging
Definition: StoreMap.h:364
#define assert(EX)
Definition: assert.h:19
static uint32 C
Definition: md4.c:43
std::atomic< uint64_t > swap_file_sz
Definition: StoreMap.h:105
StoreMapFileNos FileNos
Definition: StoreMap.h:221
void fill(const Item &value)
reset all items to the same value
Definition: StoreMap.h:145
int entryCount() const
number of writeable and readable entries
Definition: StoreMap.cc:739
Aggregates information required for updating entry metadata and headers.
Definition: StoreMap.h:181
std::atomic< uint8_t > waitingToBeFreed
Definition: StoreMap.h:81
StoreMapAnchor * anchor
StoreMap::anchors[fileNo], for convenience/speed.
Definition: StoreMap.h:193
sfileno nameByKey(const cache_key *const key) const
computes entry name (i.e., key hash) for a given entry key
Definition: StoreMap.cc:884
bool complete() const
Definition: StoreMap.h:77
int compareVersions(const sfileno oldFileno, time_t newVersion) const
Definition: StoreMap.cc:68
Anchor * openForWriting(const cache_key *const key, sfileno &fileno)
Definition: StoreMap.cc:140
Slice & sliceAt(const SliceId sliceId)
Definition: StoreMap.cc:925
Slices::Owner * slices
Definition: StoreMap.h:239
std::atomic< uint32_t > victim
starting point for purge search
Definition: StoreMap.h:171
signed_int32_t sfileno
Definition: forward.h:22
void clear()
restore default-constructed state
Definition: StoreMap.h:46
bool freeEntry(const sfileno)
Definition: StoreMap.cc:313
Anchor & anchorByKey(const cache_key *const key)
Definition: StoreMap.cc:919
const Item & at(const int index) const
Definition: StoreMap.h:139
During an update, the stored entry has two editions: stale and fresh.
Definition: StoreMap.h:185
sfileno fileNoByName(const sfileno name) const
computes anchor position for a given entry name
Definition: StoreMap.cc:894
bool hasReadableEntry(const cache_key *const)
whether the index contains a valid readable entry with the given key
Definition: StoreMap.cc:363
const Anchor * openOrCreateForReading(const cache_key *, sfileno &, const StoreEntry &)
openForReading() but creates a new entry if there is no old one
Definition: StoreMap.cc:103
void closeForUpdateFinal(Update &update)
void exportInto(StoreEntry &) const
load StoreEntry basics that were previously stored with set()
Definition: StoreMap.cc:979
StoreMapSliceId splicingPoint
the last slice in the chain still containing metadata/headers
Definition: StoreMap.h:198
const Slice & readableSlice(const AnchorId anchorId, const SliceId sliceId) const
readable slice within an entry chain opened by openForReading()
Definition: StoreMap.cc:229
StoreMapSlices Slices
Definition: StoreMap.h:226
const Anchor * peekAtWriter(const sfileno fileno) const
Definition: StoreMap.cc:297
sfileno fileNo
StoreMap::fileNos[name], for convenience/speed.
Definition: StoreMap.h:194
Anchors::Owner * anchors
Definition: StoreMap.h:238
StoreMapCleaner * cleaner
notified before a readable entry is freed
Definition: StoreMap.h:361
void disableHitValidation()
Definition: StoreMap.h:346
bool purgeOne()
either finds and frees an entry with at least 1 slice or returns false
Definition: StoreMap.cc:702
StoreMapAnchors(const int aCapacity)
Definition: StoreMap.cc:1048
bool markedForDeletion(const cache_key *const)
Definition: StoreMap.cc:355
const Anchor & peekAtEntry(const sfileno fileno) const
Definition: StoreMap.cc:307
StoreMapSlice Slice
Definition: StoreMap.h:225
void closeForReadingAndFreeIdle(const sfileno fileno)
same as closeForReading() but also frees the entry if it is unlocked
Definition: StoreMap.cc:506
sfileno name
StoreEntry position in StoreMap::fileNos, for swapping Editions.
Definition: StoreMap.h:195
void abortWriting(const sfileno fileno)
stop writing the entry, freeing its slot for others to use if possible
Definition: StoreMap.cc:251
static size_t SharedMemorySize(const int aCapacity)
Definition: StoreMap.h:130
const int capacity
total number of anchors
Definition: StoreMap.h:172
bool hitValidation
whether paranoid_hit_validation should be performed
Definition: StoreMap.h:393
std::atomic< Size > size
slice contents size
Definition: StoreMap.h:48
bool visitVictims(const NameFilter filter)
Definition: StoreMap.cc:685
StoreMapItems(const int aCapacity)
Definition: StoreMap.h:127
Anchor * openForWritingAt(sfileno fileno, bool overwriteExisting=true)
Definition: StoreMap.cc:155
virtual void noteFreeMapSlice(const StoreMapSliceId sliceId)=0
adjust slice-linked state before a locked Readable slice is erased
void abortUpdating(Update &update)
undoes partial update, unlocks, and cleans up
Definition: StoreMap.cc:269
bool openForUpdating(Update &update, sfileno fileNoHint)
finds and locks the Update entry for an exclusive metadata update
Definition: StoreMap.cc:523
bool reading() const
Definition: StoreMap.h:75
void freeChainAt(SliceId sliceId, const SliceId splicingPoint)
unconditionally frees an already locked chain of slots; no anchor maintenance
Definition: StoreMap.cc:391
uint32_t Size
Definition: StoreMap.h:31
sfileno fileNoByKey(const cache_key *const key) const
computes map entry anchor position for a given entry key
Definition: StoreMap.cc:912
StoreMapSliceId SliceId
Definition: StoreMap.h:227
aggregates anchor and slice owners for Init() caller convenience
Definition: StoreMap.h:232
std::function< bool(const sfileno name)> NameFilter
Definition: StoreMap.h:386
void switchWritingToReading(const sfileno fileno)
stop writing (or updating) the locked entry and start reading it
Definition: StoreMap.cc:211
Definition: IpcIoFile.h:23
StoreMapAnchor Anchor
Definition: StoreMap.h:222
Slice & writeableSlice(const AnchorId anchorId, const SliceId sliceId)
writeable slice within an entry chain created by openForWriting()
Definition: StoreMap.cc:221
Item & at(const int index)
Definition: StoreMap.h:132

 

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