index.go

Documentation: go.etcd.io/etcd/server/v3/mvcc

     1  // Copyright 2015 The etcd Authors
     2  //
     3  // Licensed under the Apache License, Version 2.0 (the "License");
     4  // you may not use this file except in compliance with the License.
     5  // You may obtain a copy of the License at
     6  //
     7  //     http://www.apache.org/licenses/LICENSE-2.0
     8  //
     9  // Unless required by applicable law or agreed to in writing, software
    10  // distributed under the License is distributed on an "AS IS" BASIS,
    11  // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    12  // See the License for the specific language governing permissions and
    13  // limitations under the License.
    14  
    15  package mvcc
    16  
    17  import (
    18  	"sort"
    19  	"sync"
    20  
    21  	"github.com/google/btree"
    22  	"go.uber.org/zap"
    23  )
    24  
    25  type index interface {
    26  	Get(key []byte, atRev int64) (rev, created revision, ver int64, err error)
    27  	Range(key, end []byte, atRev int64) ([][]byte, []revision)
    28  	Revisions(key, end []byte, atRev int64, limit int) ([]revision, int)
    29  	CountRevisions(key, end []byte, atRev int64) int
    30  	Put(key []byte, rev revision)
    31  	Tombstone(key []byte, rev revision) error
    32  	RangeSince(key, end []byte, rev int64) []revision
    33  	Compact(rev int64) map[revision]struct{}
    34  	Keep(rev int64) map[revision]struct{}
    35  	Equal(b index) bool
    36  
    37  	Insert(ki *keyIndex)
    38  	KeyIndex(ki *keyIndex) *keyIndex
    39  }
    40  
    41  type treeIndex struct {
    42  	sync.RWMutex
    43  	tree *btree.BTree
    44  	lg   *zap.Logger
    45  }
    46  
    47  func newTreeIndex(lg *zap.Logger) index {
    48  	return &treeIndex{
    49  		tree: btree.New(32),
    50  		lg:   lg,
    51  	}
    52  }
    53  
    54  func (ti *treeIndex) Put(key []byte, rev revision) {
    55  	keyi := &keyIndex{key: key}
    56  
    57  	ti.Lock()
    58  	defer ti.Unlock()
    59  	item := ti.tree.Get(keyi)
    60  	if item == nil {
    61  		keyi.put(ti.lg, rev.main, rev.sub)
    62  		ti.tree.ReplaceOrInsert(keyi)
    63  		return
    64  	}
    65  	okeyi := item.(*keyIndex)
    66  	okeyi.put(ti.lg, rev.main, rev.sub)
    67  }
    68  
    69  func (ti *treeIndex) Get(key []byte, atRev int64) (modified, created revision, ver int64, err error) {
    70  	keyi := &keyIndex{key: key}
    71  	ti.RLock()
    72  	defer ti.RUnlock()
    73  	if keyi = ti.keyIndex(keyi); keyi == nil {
    74  		return revision{}, revision{}, 0, ErrRevisionNotFound
    75  	}
    76  	return keyi.get(ti.lg, atRev)
    77  }
    78  
    79  func (ti *treeIndex) KeyIndex(keyi *keyIndex) *keyIndex {
    80  	ti.RLock()
    81  	defer ti.RUnlock()
    82  	return ti.keyIndex(keyi)
    83  }
    84  
    85  func (ti *treeIndex) keyIndex(keyi *keyIndex) *keyIndex {
    86  	if item := ti.tree.Get(keyi); item != nil {
    87  		return item.(*keyIndex)
    88  	}
    89  	return nil
    90  }
    91  
    92  func (ti *treeIndex) visit(key, end []byte, f func(ki *keyIndex) bool) {
    93  	keyi, endi := &keyIndex{key: key}, &keyIndex{key: end}
    94  
    95  	ti.RLock()
    96  	defer ti.RUnlock()
    97  
    98  	ti.tree.AscendGreaterOrEqual(keyi, func(item btree.Item) bool {
    99  		if len(endi.key) > 0 && !item.Less(endi) {
   100  			return false
   101  		}
   102  		if !f(item.(*keyIndex)) {
   103  			return false
   104  		}
   105  		return true
   106  	})
   107  }
   108  
   109  func (ti *treeIndex) Revisions(key, end []byte, atRev int64, limit int) (revs []revision, total int) {
   110  	if end == nil {
   111  		rev, _, _, err := ti.Get(key, atRev)
   112  		if err != nil {
   113  			return nil, 0
   114  		}
   115  		return []revision{rev}, 1
   116  	}
   117  	ti.visit(key, end, func(ki *keyIndex) bool {
   118  		if rev, _, _, err := ki.get(ti.lg, atRev); err == nil {
   119  			if limit <= 0 || len(revs) < limit {
   120  				revs = append(revs, rev)
   121  			}
   122  			total++
   123  		}
   124  		return true
   125  	})
   126  	return revs, total
   127  }
   128  
   129  func (ti *treeIndex) CountRevisions(key, end []byte, atRev int64) int {
   130  	if end == nil {
   131  		_, _, _, err := ti.Get(key, atRev)
   132  		if err != nil {
   133  			return 0
   134  		}
   135  		return 1
   136  	}
   137  	total := 0
   138  	ti.visit(key, end, func(ki *keyIndex) bool {
   139  		if _, _, _, err := ki.get(ti.lg, atRev); err == nil {
   140  			total++
   141  		}
   142  		return true
   143  	})
   144  	return total
   145  }
   146  
   147  func (ti *treeIndex) Range(key, end []byte, atRev int64) (keys [][]byte, revs []revision) {
   148  	if end == nil {
   149  		rev, _, _, err := ti.Get(key, atRev)
   150  		if err != nil {
   151  			return nil, nil
   152  		}
   153  		return [][]byte{key}, []revision{rev}
   154  	}
   155  	ti.visit(key, end, func(ki *keyIndex) bool {
   156  		if rev, _, _, err := ki.get(ti.lg, atRev); err == nil {
   157  			revs = append(revs, rev)
   158  			keys = append(keys, ki.key)
   159  		}
   160  		return true
   161  	})
   162  	return keys, revs
   163  }
   164  
   165  func (ti *treeIndex) Tombstone(key []byte, rev revision) error {
   166  	keyi := &keyIndex{key: key}
   167  
   168  	ti.Lock()
   169  	defer ti.Unlock()
   170  	item := ti.tree.Get(keyi)
   171  	if item == nil {
   172  		return ErrRevisionNotFound
   173  	}
   174  
   175  	ki := item.(*keyIndex)
   176  	return ki.tombstone(ti.lg, rev.main, rev.sub)
   177  }
   178  
   179  // RangeSince returns all revisions from key(including) to end(excluding)
   180  // at or after the given rev. The returned slice is sorted in the order
   181  // of revision.
   182  func (ti *treeIndex) RangeSince(key, end []byte, rev int64) []revision {
   183  	keyi := &keyIndex{key: key}
   184  
   185  	ti.RLock()
   186  	defer ti.RUnlock()
   187  
   188  	if end == nil {
   189  		item := ti.tree.Get(keyi)
   190  		if item == nil {
   191  			return nil
   192  		}
   193  		keyi = item.(*keyIndex)
   194  		return keyi.since(ti.lg, rev)
   195  	}
   196  
   197  	endi := &keyIndex{key: end}
   198  	var revs []revision
   199  	ti.tree.AscendGreaterOrEqual(keyi, func(item btree.Item) bool {
   200  		if len(endi.key) > 0 && !item.Less(endi) {
   201  			return false
   202  		}
   203  		curKeyi := item.(*keyIndex)
   204  		revs = append(revs, curKeyi.since(ti.lg, rev)...)
   205  		return true
   206  	})
   207  	sort.Sort(revisions(revs))
   208  
   209  	return revs
   210  }
   211  
   212  func (ti *treeIndex) Compact(rev int64) map[revision]struct{} {
   213  	available := make(map[revision]struct{})
   214  	ti.lg.Info("compact tree index", zap.Int64("revision", rev))
   215  	ti.Lock()
   216  	clone := ti.tree.Clone()
   217  	ti.Unlock()
   218  
   219  	clone.Ascend(func(item btree.Item) bool {
   220  		keyi := item.(*keyIndex)
   221  		//Lock is needed here to prevent modification to the keyIndex while
   222  		//compaction is going on or revision added to empty before deletion
   223  		ti.Lock()
   224  		keyi.compact(ti.lg, rev, available)
   225  		if keyi.isEmpty() {
   226  			item := ti.tree.Delete(keyi)
   227  			if item == nil {
   228  				ti.lg.Panic("failed to delete during compaction")
   229  			}
   230  		}
   231  		ti.Unlock()
   232  		return true
   233  	})
   234  	return available
   235  }
   236  
   237  // Keep finds all revisions to be kept for a Compaction at the given rev.
   238  func (ti *treeIndex) Keep(rev int64) map[revision]struct{} {
   239  	available := make(map[revision]struct{})
   240  	ti.RLock()
   241  	defer ti.RUnlock()
   242  	ti.tree.Ascend(func(i btree.Item) bool {
   243  		keyi := i.(*keyIndex)
   244  		keyi.keep(rev, available)
   245  		return true
   246  	})
   247  	return available
   248  }
   249  
   250  func (ti *treeIndex) Equal(bi index) bool {
   251  	b := bi.(*treeIndex)
   252  
   253  	if ti.tree.Len() != b.tree.Len() {
   254  		return false
   255  	}
   256  
   257  	equal := true
   258  
   259  	ti.tree.Ascend(func(item btree.Item) bool {
   260  		aki := item.(*keyIndex)
   261  		bki := b.tree.Get(item).(*keyIndex)
   262  		if !aki.equal(bki) {
   263  			equal = false
   264  			return false
   265  		}
   266  		return true
   267  	})
   268  
   269  	return equal
   270  }
   271  
   272  func (ti *treeIndex) Insert(ki *keyIndex) {
   273  	ti.Lock()
   274  	defer ti.Unlock()
   275  	ti.tree.ReplaceOrInsert(ki)
   276  }
   277
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