github.com/m3db/m3@v1.5.0/src/m3ninx/index/segment/mem/concurrent_postings_map.go (about)

     1  // Copyright (c) 2018 Uber Technologies, Inc.
     2  //
     3  // Permission is hereby granted, free of charge, to any person obtaining a copy
     4  // of this software and associated documentation files (the "Software"), to deal
     5  // in the Software without restriction, including without limitation the rights
     6  // to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
     7  // copies of the Software, and to permit persons to whom the Software is
     8  // furnished to do so, subject to the following conditions:
     9  //
    10  // The above copyright notice and this permission notice shall be included in
    11  // all copies or substantial portions of the Software.
    12  //
    13  // THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
    14  // IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
    15  // FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
    16  // AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
    17  // LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
    18  // OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
    19  // THE SOFTWARE.
    20  
    21  package mem
    22  
    23  import (
    24  	"regexp"
    25  	"sync"
    26  
    27  	"github.com/m3db/m3/src/m3ninx/postings"
    28  	"github.com/m3db/m3/src/m3ninx/postings/roaring"
    29  )
    30  
    31  // concurrentPostingsMap is a thread-safe map from []byte -> postings.List.
    32  type concurrentPostingsMap struct {
    33  	sync.RWMutex
    34  	*postingsMap
    35  
    36  	opts Options
    37  }
    38  
    39  // newConcurrentPostingsMap returns a new thread-safe map from []byte -> postings.List.
    40  func newConcurrentPostingsMap(opts Options) *concurrentPostingsMap {
    41  	return &concurrentPostingsMap{
    42  		postingsMap: newPostingsMap(opts.InitialCapacity()),
    43  		opts:        opts,
    44  	}
    45  }
    46  
    47  // Add adds the provided `id` to the postings.List backing `key`.
    48  func (m *concurrentPostingsMap) Add(key []byte, id postings.ID) error {
    49  	// Try read lock to see if we already have a postings list for the given value.
    50  	m.RLock()
    51  	p, ok := m.postingsMap.Get(key)
    52  	m.RUnlock()
    53  
    54  	// We have a postings list, insert the ID and move on.
    55  	if ok {
    56  		return p.Insert(id)
    57  	}
    58  
    59  	// A corresponding postings list doesn't exist, time to acquire write lock.
    60  	m.Lock()
    61  	p, ok = m.postingsMap.Get(key)
    62  
    63  	// Check if the corresponding postings list has been created since we released lock.
    64  	if ok {
    65  		m.Unlock()
    66  		return p.Insert(id)
    67  	}
    68  
    69  	// Create a new posting list for the term, and insert into fieldValues.
    70  	p = m.opts.PostingsListPool().Get()
    71  	m.postingsMap.SetUnsafe(key, p, postingsMapSetUnsafeOptions{
    72  		NoCopyKey:     true,
    73  		NoFinalizeKey: true,
    74  	})
    75  	m.Unlock()
    76  	return p.Insert(id)
    77  }
    78  
    79  // Keys returns the keys known to the map.
    80  func (m *concurrentPostingsMap) Keys() *termsIter {
    81  	m.RLock()
    82  	defer m.RUnlock()
    83  	keys := m.opts.BytesSliceArrayPool().Get()
    84  	for _, entry := range m.Iter() {
    85  		keys = append(keys, entry.Key())
    86  	}
    87  	return newTermsIter(keys, m, m.opts)
    88  }
    89  
    90  // Get returns the postings.List backing `key`.
    91  func (m *concurrentPostingsMap) Get(key []byte) (postings.List, bool) {
    92  	m.RLock()
    93  	p, ok := m.postingsMap.Get(key)
    94  	m.RUnlock()
    95  	if ok {
    96  		return p, true
    97  	}
    98  	return nil, false
    99  }
   100  
   101  // GetRegex returns the union of the postings lists whose keys match the
   102  // provided regexp.
   103  func (m *concurrentPostingsMap) GetRegex(re *regexp.Regexp) (postings.List, bool) {
   104  	lists := make([]postings.List, 0, m.postingsMap.Len())
   105  
   106  	m.RLock()
   107  	for _, mapEntry := range m.postingsMap.Iter() {
   108  		// TODO: Evaluate lock contention caused by holding on to the read lock while
   109  		// evaluating this predicate.
   110  		// TODO: Evaluate if performing a prefix match would speed up the common case.
   111  		if re.Match(mapEntry.Key()) {
   112  			lists = append(lists, mapEntry.Value())
   113  		}
   114  	}
   115  	m.RUnlock()
   116  
   117  	if len(lists) == 0 {
   118  		return nil, false
   119  	}
   120  
   121  	result, _ := roaring.Union(lists)
   122  	return result, true
   123  }