1 // Copyright (c) 2011-present, Facebook, Inc. All rights reserved.
2 // This source code is licensed under both the GPLv2 (found in the
3 // COPYING file in the root directory) and Apache 2.0 License
4 // (found in the LICENSE.Apache file in the root directory).
13 #include "db/dbformat.h"
14 #include "memory/arena.h"
15 #include "rocksdb/db.h"
16 #include "rocksdb/iterator.h"
17 #include "rocksdb/options.h"
18 #include "table/internal_iterator.h"
20 namespace ROCKSDB_NAMESPACE
{
25 class ColumnFamilyData
;
26 class ForwardLevelIterator
;
27 class VersionStorageInfo
;
30 class MinIterComparator
{
32 explicit MinIterComparator(const Comparator
* comparator
) :
33 comparator_(comparator
) {}
35 bool operator()(InternalIterator
* a
, InternalIterator
* b
) {
36 return comparator_
->Compare(a
->key(), b
->key()) > 0;
39 const Comparator
* comparator_
;
42 typedef std::priority_queue
<InternalIterator
*, std::vector
<InternalIterator
*>,
43 MinIterComparator
> MinIterHeap
;
46 * ForwardIterator is a special type of iterator that only supports Seek()
47 * and Next(). It is expected to perform better than TailingIterator by
48 * removing the encapsulation and making all information accessible within
49 * the iterator. At the current implementation, snapshot is taken at the
50 * time Seek() is called. The Next() followed do not see new values after.
52 class ForwardIterator
: public InternalIterator
{
54 ForwardIterator(DBImpl
* db
, const ReadOptions
& read_options
,
55 ColumnFamilyData
* cfd
, SuperVersion
* current_sv
= nullptr);
56 virtual ~ForwardIterator();
58 void SeekForPrev(const Slice
& /*target*/) override
{
59 status_
= Status::NotSupported("ForwardIterator::SeekForPrev()");
62 void SeekToLast() override
{
63 status_
= Status::NotSupported("ForwardIterator::SeekToLast()");
66 void Prev() override
{
67 status_
= Status::NotSupported("ForwardIterator::Prev");
71 virtual bool Valid() const override
;
72 void SeekToFirst() override
;
73 virtual void Seek(const Slice
& target
) override
;
74 virtual void Next() override
;
75 virtual Slice
key() const override
;
76 virtual Slice
value() const override
;
77 virtual Status
status() const override
;
78 virtual Status
GetProperty(std::string prop_name
, std::string
* prop
) override
;
79 virtual void SetPinnedItersMgr(
80 PinnedIteratorsManager
* pinned_iters_mgr
) override
;
81 virtual bool IsKeyPinned() const override
;
82 virtual bool IsValuePinned() const override
;
84 bool TEST_CheckDeletedIters(int* deleted_iters
, int* num_iters
);
87 void Cleanup(bool release_sv
);
88 // Unreference and, if needed, clean up the current SuperVersion. This is
89 // either done immediately or deferred until this iterator is unpinned by
90 // PinnedIteratorsManager.
92 static void SVCleanup(
93 DBImpl
* db
, SuperVersion
* sv
, bool background_purge_on_iterator_cleanup
);
94 static void DeferredSVCleanup(void* arg
);
96 void RebuildIterators(bool refresh_sv
);
97 void RenewIterators();
98 void BuildLevelIterators(const VersionStorageInfo
* vstorage
);
99 void ResetIncompleteIterators();
100 void SeekInternal(const Slice
& internal_key
, bool seek_to_first
);
101 void UpdateCurrent();
102 bool NeedToSeekImmutable(const Slice
& internal_key
);
103 void DeleteCurrentIter();
104 uint32_t FindFileInRange(
105 const std::vector
<FileMetaData
*>& files
, const Slice
& internal_key
,
106 uint32_t left
, uint32_t right
);
108 bool IsOverUpperBound(const Slice
& internal_key
) const;
110 // Set PinnedIteratorsManager for all children Iterators, this function should
111 // be called whenever we update children Iterators or pinned_iters_mgr_.
112 void UpdateChildrenPinnedItersMgr();
114 // A helper function that will release iter in the proper manner, or pass it
115 // to pinned_iters_mgr_ to release it later if pinning is enabled.
116 void DeleteIterator(InternalIterator
* iter
, bool is_arena
= false);
119 const ReadOptions read_options_
;
120 ColumnFamilyData
* const cfd_
;
121 const SliceTransform
* const prefix_extractor_
;
122 const Comparator
* user_comparator_
;
123 MinIterHeap immutable_min_heap_
;
126 InternalIterator
* mutable_iter_
;
127 std::vector
<InternalIterator
*> imm_iters_
;
128 std::vector
<InternalIterator
*> l0_iters_
;
129 std::vector
<ForwardLevelIterator
*> level_iters_
;
130 InternalIterator
* current_
;
133 // Internal iterator status; set only by one of the unsupported methods.
135 // Status of immutable iterators, maintained here to avoid iterating over
136 // all of them in status().
137 Status immutable_status_
;
138 // Indicates that at least one of the immutable iterators pointed to a key
139 // larger than iterate_upper_bound and was therefore destroyed. Seek() may
140 // need to rebuild such iterators.
141 bool has_iter_trimmed_for_upper_bound_
;
142 // Is current key larger than iterate_upper_bound? If so, makes Valid()
144 bool current_over_upper_bound_
;
146 // Left endpoint of the range of keys that immutable iterators currently
147 // cover. When Seek() is called with a key that's within that range, immutable
148 // iterators don't need to be moved; see NeedToSeekImmutable(). This key is
149 // included in the range after a Seek(), but excluded when advancing the
150 // iterator using Next().
153 bool is_prev_inclusive_
;
155 PinnedIteratorsManager
* pinned_iters_mgr_
;
159 } // namespace ROCKSDB_NAMESPACE
160 #endif // ROCKSDB_LITE