QGIS API Documentation  3.8.0-Zanzibar (11aff65)
qgsvectorlayercache.cpp
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1 /***************************************************************************
2  qgsvectorlayercache.cpp
3  Cache features of a vector layer
4  -------------------
5  begin : January 2013
6  copyright : (C) Matthias Kuhn
7  email : matthias at opengis dot ch
8 
9  ***************************************************************************
10  * *
11  * This program is free software; you can redistribute it and/or modify *
12  * it under the terms of the GNU General Public License as published by *
13  * the Free Software Foundation; either version 2 of the License, or *
14  * (at your option) any later version. *
15  * *
16  ***************************************************************************/
17 
18 #include "qgsvectorlayercache.h"
19 #include "qgscacheindex.h"
21 #include "qgsvectorlayerjoininfo.h"
23 #include "qgsvectorlayer.h"
24 
25 QgsVectorLayerCache::QgsVectorLayerCache( QgsVectorLayer *layer, int cacheSize, QObject *parent )
26  : QObject( parent )
27  , mLayer( layer )
28 {
29  mCache.setMaxCost( cacheSize );
30 
31  connect( mLayer, &QgsVectorLayer::featureDeleted, this, &QgsVectorLayerCache::featureDeleted );
32  connect( mLayer, &QgsVectorLayer::featureAdded, this, &QgsVectorLayerCache::onFeatureAdded );
33  connect( mLayer, &QgsVectorLayer::destroyed, this, &QgsVectorLayerCache::layerDeleted );
34 
35  setCacheGeometry( true );
38 
39  connect( mLayer, &QgsVectorLayer::attributeDeleted, this, &QgsVectorLayerCache::attributeDeleted );
40  connect( mLayer, &QgsVectorLayer::updatedFields, this, &QgsVectorLayerCache::invalidate );
41  connect( mLayer, &QgsVectorLayer::dataChanged, this, &QgsVectorLayerCache::invalidate );
42  connect( mLayer, &QgsVectorLayer::attributeValueChanged, this, &QgsVectorLayerCache::onAttributeValueChanged );
43 
44  connectJoinedLayers();
45 }
46 
48 {
49  qDeleteAll( mCacheIndices );
50  mCacheIndices.clear();
51 }
52 
54 {
55  mCache.setMaxCost( cacheSize );
56 }
57 
59 {
60  return mCache.maxCost();
61 }
62 
64 {
65  bool shouldCacheGeometry = cacheGeometry && mLayer->isSpatial();
66  bool mustInvalidate = shouldCacheGeometry && !mCacheGeometry; // going from no geometry -> geometry, so have to clear existing cache entries
67  mCacheGeometry = shouldCacheGeometry;
68  if ( cacheGeometry )
69  {
70  connect( mLayer, &QgsVectorLayer::geometryChanged, this, &QgsVectorLayerCache::geometryChanged );
71  }
72  else
73  {
74  disconnect( mLayer, &QgsVectorLayer::geometryChanged, this, &QgsVectorLayerCache::geometryChanged );
75  }
76  if ( mustInvalidate )
77  {
78  invalidate();
79  }
80 }
81 
83 {
84  mCachedAttributes = attributes;
85 }
86 
87 void QgsVectorLayerCache::setFullCache( bool fullCache )
88 {
89  mFullCache = fullCache;
90 
91  if ( mFullCache )
92  {
93  // Add a little more than necessary...
94  setCacheSize( mLayer->featureCount() + 100 );
95 
96  // Initialize the cache...
98  .setSubsetOfAttributes( mCachedAttributes )
99  .setFlags( mCacheGeometry ? QgsFeatureRequest::NoFlags : QgsFeatureRequest::NoGeometry ) ) );
100 
101  int i = 0;
102 
103  QTime t;
104  t.start();
105 
106  QgsFeature f;
107  while ( it.nextFeature( f ) )
108  {
109  ++i;
110 
111  if ( t.elapsed() > 1000 )
112  {
113  bool cancel = false;
114  emit progress( i, cancel );
115  if ( cancel )
116  break;
117 
118  t.restart();
119  }
120  }
121 
122  it.close();
123 
124  emit finished();
125  }
126 }
127 
129 {
130  mCacheIndices.append( cacheIndex );
131 }
132 
133 void QgsVectorLayerCache::setCacheAddedAttributes( bool cacheAddedAttributes )
134 {
135  if ( cacheAddedAttributes )
136  {
137  connect( mLayer, &QgsVectorLayer::attributeAdded, this, &QgsVectorLayerCache::attributeAdded );
138  }
139  else
140  {
141  disconnect( mLayer, &QgsVectorLayer::attributeAdded, this, &QgsVectorLayerCache::attributeAdded );
142  }
143 }
144 
145 bool QgsVectorLayerCache::featureAtId( QgsFeatureId featureId, QgsFeature &feature, bool skipCache )
146 {
147  bool featureFound = false;
148 
149  QgsCachedFeature *cachedFeature = nullptr;
150 
151  if ( !skipCache )
152  {
153  cachedFeature = mCache[ featureId ];
154  }
155 
156  if ( cachedFeature )
157  {
158  feature = QgsFeature( *cachedFeature->feature() );
159  featureFound = true;
160  }
161  else if ( mLayer->getFeatures( QgsFeatureRequest()
162  .setFilterFid( featureId )
163  .setSubsetOfAttributes( mCachedAttributes )
164  .setFlags( !mCacheGeometry ? QgsFeatureRequest::NoGeometry : QgsFeatureRequest::Flags( nullptr ) ) )
165  .nextFeature( feature ) )
166  {
167  cacheFeature( feature );
168  featureFound = true;
169  }
170 
171  return featureFound;
172 }
173 
175 {
176  return mCache.remove( fid );
177 }
178 
180 {
181  return mLayer;
182 }
183 
185 {
186  return mLayer->crs();
187 }
188 
190 {
191  return mLayer->wkbType();
192 }
193 
195 {
196  return mLayer->fields();
197 }
198 
200 {
201  return mLayer->featureCount();
202 }
203 
205 {
206  // If a request is too large for the cache don't notify to prevent from indexing incomplete requests
207  if ( fids.count() <= mCache.size() )
208  {
209  for ( const auto &idx : qgis::as_const( mCacheIndices ) )
210  {
211  idx->requestCompleted( featureRequest, fids );
212  }
213  if ( featureRequest.filterType() == QgsFeatureRequest::FilterNone &&
214  ( featureRequest.filterRect().isNull() || featureRequest.filterRect().contains( mLayer->extent() ) ) )
215  {
216  mFullCache = true;
217  }
218  }
219 }
220 
222 {
223  const auto constMCacheIndices = mCacheIndices;
224  for ( QgsAbstractCacheIndex *idx : constMCacheIndices )
225  {
226  idx->flushFeature( fid );
227  }
228 }
229 
230 void QgsVectorLayerCache::onAttributeValueChanged( QgsFeatureId fid, int field, const QVariant &value )
231 {
232  QgsCachedFeature *cachedFeat = mCache[ fid ];
233 
234  if ( cachedFeat )
235  {
236  cachedFeat->mFeature->setAttribute( field, value );
237  }
238 
239  emit attributeValueChanged( fid, field, value );
240 }
241 
242 void QgsVectorLayerCache::onJoinAttributeValueChanged( QgsFeatureId fid, int field, const QVariant &value )
243 {
244  const QgsVectorLayer *joinLayer = qobject_cast<const QgsVectorLayer *>( sender() );
245 
246  const auto constVectorJoins = mLayer->vectorJoins();
247  for ( const QgsVectorLayerJoinInfo &info : constVectorJoins )
248  {
249  if ( joinLayer == info.joinLayer() )
250  {
251  const QgsFeature feature = mLayer->joinBuffer()->targetedFeatureOf( &info, joinLayer->getFeature( fid ) );
252 
253  const QString fieldName = info.prefixedFieldName( joinLayer->fields().field( field ) );
254  const int fieldIndex = mLayer->fields().indexFromName( fieldName );
255 
256  if ( feature.isValid() && fieldIndex != -1 )
257  {
258  onAttributeValueChanged( feature.id(), fieldIndex, value );
259  return;
260  }
261  }
262  }
263 }
264 
265 void QgsVectorLayerCache::featureDeleted( QgsFeatureId fid )
266 {
267  mCache.remove( fid );
268 }
269 
270 void QgsVectorLayerCache::onFeatureAdded( QgsFeatureId fid )
271 {
272  if ( mFullCache )
273  {
274  if ( cacheSize() <= mLayer->featureCount() )
275  {
276  setCacheSize( mLayer->featureCount() + 100 );
277  }
278 
279  QgsFeature feat;
280  featureAtId( fid, feat );
281  }
282  emit featureAdded( fid );
283 }
284 
285 void QgsVectorLayerCache::attributeAdded( int field )
286 {
287  Q_UNUSED( field )
288  mCachedAttributes.append( field );
289  invalidate();
290 }
291 
292 void QgsVectorLayerCache::attributeDeleted( int field )
293 {
294  QgsAttributeList attrs = mCachedAttributes;
295  mCachedAttributes.clear();
296 
297  const auto constAttrs = attrs;
298  for ( int attr : constAttrs )
299  {
300  if ( attr < field )
301  mCachedAttributes << attr;
302  else if ( attr > field )
303  mCachedAttributes << attr - 1;
304  }
305 }
306 
307 void QgsVectorLayerCache::geometryChanged( QgsFeatureId fid, const QgsGeometry &geom )
308 {
309  QgsCachedFeature *cachedFeat = mCache[ fid ];
310 
311  if ( cachedFeat )
312  {
313  cachedFeat->mFeature->setGeometry( geom );
314  }
315 }
316 
317 void QgsVectorLayerCache::layerDeleted()
318 {
319  emit cachedLayerDeleted();
320  mLayer = nullptr;
321 }
322 
323 void QgsVectorLayerCache::invalidate()
324 {
325  mCache.clear();
326  mFullCache = false;
327  emit invalidated();
328 }
329 
330 bool QgsVectorLayerCache::canUseCacheForRequest( const QgsFeatureRequest &featureRequest, QgsFeatureIterator &it )
331 {
332  // check first for available indices
333  const auto constMCacheIndices = mCacheIndices;
334  for ( QgsAbstractCacheIndex *idx : constMCacheIndices )
335  {
336  if ( idx->getCacheIterator( it, featureRequest ) )
337  {
338  return true;
339  }
340  }
341 
342  // no indexes available, but maybe we have already cached all required features anyway?
343  switch ( featureRequest.filterType() )
344  {
346  {
347  if ( mCache.contains( featureRequest.filterFid() ) )
348  {
349  it = QgsFeatureIterator( new QgsCachedFeatureIterator( this, featureRequest ) );
350  return true;
351  }
352  break;
353  }
355  {
356  if ( mCache.keys().toSet().contains( featureRequest.filterFids() ) )
357  {
358  it = QgsFeatureIterator( new QgsCachedFeatureIterator( this, featureRequest ) );
359  return true;
360  }
361  break;
362  }
365  {
366  if ( mFullCache )
367  {
368  it = QgsFeatureIterator( new QgsCachedFeatureIterator( this, featureRequest ) );
369  return true;
370  }
371  break;
372  }
373 
374  }
375  return false;
376 }
377 
379 {
381  bool requiresWriterIt = true; // If a not yet cached, but cachable request is made, this stays true.
382 
383  if ( checkInformationCovered( featureRequest ) )
384  {
385  // If we have a full cache available, run on this
386  if ( mFullCache )
387  {
388  it = QgsFeatureIterator( new QgsCachedFeatureIterator( this, featureRequest ) );
389  requiresWriterIt = false;
390  }
391  else
392  {
393  // may still be able to satisfy request using cache
394  requiresWriterIt = !canUseCacheForRequest( featureRequest, it );
395  }
396  }
397  else
398  {
399  // Let the layer answer the request, so no caching of requests
400  // we don't want to cache is done
401  requiresWriterIt = false;
402  it = mLayer->getFeatures( featureRequest );
403  }
404 
405  if ( requiresWriterIt && mLayer->dataProvider() )
406  {
407  // No index was able to satisfy the request
408  QgsFeatureRequest myRequest = QgsFeatureRequest( featureRequest );
409 
410  // Make sure if we cache the geometry, it gets fetched
411  if ( mCacheGeometry && mLayer->isSpatial() )
412  myRequest.setFlags( featureRequest.flags() & ~QgsFeatureRequest::NoGeometry );
413 
414  // Make sure, all the cached attributes are requested as well
415  QSet<int> attrs = featureRequest.subsetOfAttributes().toSet() + mCachedAttributes.toSet();
416  myRequest.setSubsetOfAttributes( attrs.toList() );
417 
418  it = QgsFeatureIterator( new QgsCachedFeatureWriterIterator( this, myRequest ) );
419  }
420 
421  return it;
422 }
423 
425 {
426  return mCache.contains( fid );
427 }
428 
430 {
431  QgsAttributeList requestedAttributes;
432 
433  if ( !featureRequest.flags().testFlag( QgsFeatureRequest::SubsetOfAttributes ) )
434  {
435  requestedAttributes = mLayer->attributeList();
436  }
437  else
438  {
439  requestedAttributes = featureRequest.subsetOfAttributes();
440  }
441 
442  // Check if we even cache the information requested
443  const auto constRequestedAttributes = requestedAttributes;
444  for ( int attr : constRequestedAttributes )
445  {
446  if ( !mCachedAttributes.contains( attr ) )
447  {
448  return false;
449  }
450  }
451 
452  // If the request needs geometry but we don't cache this...
453  return !( !featureRequest.flags().testFlag( QgsFeatureRequest::NoGeometry )
454  && !mCacheGeometry );
455 }
456 
457 void QgsVectorLayerCache::connectJoinedLayers() const
458 {
459  const auto constVectorJoins = mLayer->vectorJoins();
460  for ( const QgsVectorLayerJoinInfo &info : constVectorJoins )
461  {
462  const QgsVectorLayer *vl = info.joinLayer();
463  if ( vl )
464  connect( vl, &QgsVectorLayer::attributeValueChanged, this, &QgsVectorLayerCache::onJoinAttributeValueChanged );
465  }
466 }
bool isValid() const
Returns the validity of this feature.
Definition: qgsfeature.cpp:183
QgsFeatureId id
Definition: qgsfeature.h:64
Wrapper for iterator of features from vector data provider or vector layer.
bool contains(const QgsRectangle &rect) const
Returns true when rectangle contains other rectangle.
Definition: qgsrectangle.h:342
friend class QgsCachedFeatureWriterIterator
Filter using feature ID.
Filter using feature IDs.
QSet< QgsFeatureId > QgsFeatureIds
Definition: qgsfeatureid.h:34
QgsVectorLayerCache(QgsVectorLayer *layer, int cacheSize, QObject *parent=nullptr)
const Flags & flags() const
void invalidated()
The cache has been invalidated and cleared.
bool cacheGeometry() const
Returns true if the cache will fetch and cache feature geometries.
QgsWkbTypes::Type wkbType() const FINAL
Returns the WKBType or WKBUnknown in case of error.
bool removeCachedFeature(QgsFeatureId fid)
Removes the feature identified by fid from the cache if present.
QgsFeature getFeature(QgsFeatureId fid) const
Queries the layer for the feature with the given id.
QgsFeatureId filterFid() const
Gets the feature ID that should be fetched.
qint64 QgsFeatureId
Definition: qgsfeatureid.h:25
QgsFeatureRequest & setSubsetOfAttributes(const QgsAttributeList &attrs)
Set a subset of attributes that will be fetched.
FilterType filterType() const
Returns the filter type which is currently set on this request.
Container of fields for a vector layer.
Definition: qgsfields.h:42
const QgsFeatureIds & filterFids() const
Gets feature IDs that should be fetched.
A geometry is the spatial representation of a feature.
Definition: qgsgeometry.h:111
void requestCompleted(const QgsFeatureRequest &featureRequest, const QgsFeatureIds &fids)
Gets called, whenever the full list of feature ids for a certain request is known.
QgsVectorLayer * layer()
Returns the layer to which this cache belongs.
The feature class encapsulates a single feature including its id, geometry and a list of field/values...
Definition: qgsfeature.h:55
void attributeValueChanged(QgsFeatureId fid, int field, const QVariant &value)
Emitted when an attribute is changed.
const QgsRectangle & filterRect() const
Returns the rectangle from which features will be taken.
void featureDeleted(QgsFeatureId fid)
Emitted when a feature has been deleted.
bool isSpatial() const FINAL
Returns true if this is a geometry layer and false in case of NoGeometry (table only) or UnknownGeome...
void setCacheSubsetOfAttributes(const QgsAttributeList &attributes)
Set the subset of attributes to be cached.
void featureAdded(QgsFeatureId fid)
Emitted when a new feature has been added to the layer and this cache.
Type
The WKB type describes the number of dimensions a geometry has.
Definition: qgswkbtypes.h:68
int indexFromName(const QString &fieldName) const
Gets the field index from the field name.
Definition: qgsfields.cpp:202
const QList< QgsVectorLayerJoinInfo > vectorJoins() const
QgsFields fields() const FINAL
Returns the list of fields of this layer.
bool isFidCached(QgsFeatureId fid) const
Check if a certain feature id is cached.
QgsCoordinateReferenceSystem sourceCrs() const
Returns the coordinate reference system for features in the cache.
long featureCount(const QString &legendKey) const
Number of features rendered with specified legend key.
void progress(int i, bool &cancel)
When filling the cache, this signal gets emitted periodically to notify about the progress and to be ...
Defines left outer join from our vector layer to some other vector layer.
This class wraps a request for features to a vector layer (or directly its vector data provider)...
void geometryChanged(QgsFeatureId fid, const QgsGeometry &geometry)
Emitted whenever a geometry change is done in the edit buffer.
QgsAttributeList attributeList() const
Returns list of attribute indexes.
QgsFields fields() const
Returns the fields associated with features in the cache.
void attributeValueChanged(QgsFeatureId fid, int idx, const QVariant &value)
Emitted whenever an attribute value change is done in the edit buffer.
void featureAdded(QgsFeatureId fid)
Emitted when a new feature has been added to the layer.
Fetch only a subset of attributes (setSubsetOfAttributes sets this flag)
void cachedLayerDeleted()
Is emitted when the cached layer is deleted.
QgsRectangle extent() const FINAL
Returns the extent of the layer.
bool checkInformationCovered(const QgsFeatureRequest &featureRequest)
Checks if the information required to complete the request is cached.
QgsAttributeList subsetOfAttributes() const
Returns the subset of attributes which at least need to be fetched.
QgsVectorLayerJoinBuffer * joinBuffer()
Returns the join buffer object.
void attributeAdded(int idx)
Will be emitted, when a new attribute has been added to this vector layer.
long featureCount() const
Returns the number of features contained in the source, or -1 if the feature count is unknown...
Abstract base class for cache indices.
Definition: qgscacheindex.h:31
QgsFeature targetedFeatureOf(const QgsVectorLayerJoinInfo *info, const QgsFeature &feature) const
Returns the targeted feature corresponding to the joined feature.
No filter is applied.
void setCacheGeometry(bool cacheGeometry)
Enable or disable the caching of geometries.
void setFullCache(bool fullCache)
This enables or disables full caching.
bool featureAtId(QgsFeatureId featureId, QgsFeature &feature, bool skipCache=false)
Gets the feature at the given feature id.
void setCacheSize(int cacheSize)
Sets the maximum number of features to keep in the cache.
This class represents a coordinate reference system (CRS).
QgsWkbTypes::Type wkbType() const
Returns the geometry type for features in the cache.
bool isNull() const
Test if the rectangle is null (all coordinates zero or after call to setMinimal()).
Definition: qgsrectangle.h:436
void dataChanged()
Data of layer changed.
QgsFeatureIterator getFeatures(const QgsFeatureRequest &request=QgsFeatureRequest()) const FINAL
Queries the layer for features specified in request.
void featureRemoved(QgsFeatureId fid)
Gets called, whenever a feature has been removed.
int cacheSize()
Returns the maximum number of features this cache will hold.
QgsVectorDataProvider * dataProvider() FINAL
Returns the layer&#39;s data provider, it may be nullptr.
QList< int > QgsAttributeList
Definition: qgsfield.h:27
bool nextFeature(QgsFeature &f)
void attributeDeleted(int idx)
Will be emitted, when an attribute has been deleted from this vector layer.
Geometry is not required. It may still be returned if e.g. required for a filter condition.
void addCacheIndex(QgsAbstractCacheIndex *cacheIndex)
Adds a QgsAbstractCacheIndex to this cache.
Represents a vector layer which manages a vector based data sets.
QgsFeatureIterator getFeatures(const QgsFeatureRequest &featureRequest=QgsFeatureRequest())
Query this VectorLayerCache for features.
void updatedFields()
Emitted whenever the fields available from this layer have been changed.
void finished()
When filling the cache, this signal gets emitted once the cache is fully initialized.
friend class QgsCachedFeatureIterator
QgsField field(int fieldIdx) const
Gets field at particular index (must be in range 0..N-1)
Definition: qgsfields.cpp:168
QgsCoordinateReferenceSystem crs
Definition: qgsmaplayer.h:85
void setCacheAddedAttributes(bool cacheAddedAttributes)
If this is enabled, the subset of cached attributes will automatically be extended to also include ne...
QgsFeatureRequest & setFlags(QgsFeatureRequest::Flags flags)
Sets flags that affect how features will be fetched.