[processing][api] Add mechanism to get basic algorithm properties

efficiently for many calls Allows retrieval of some basic algorithm properties (display name, icon) in an optimised way for many calls. (Avoiding multiple expensive algorithmById lookups)
qgis · Apr 20, 2023 · 70f2adb · 70f2adb
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diff --git a/python/core/auto_generated/processing/qgsprocessingregistry.sip.in b/python/core/auto_generated/processing/qgsprocessingregistry.sip.in
@@ -10,6 +10,30 @@
 
 
 
+class QgsProcessingAlgorithmInformation
+{
+%Docstring(signature="appended")
+*************************************************************************
+
+This program is free software; you can redistribute it and/or modify  *
+it under the terms of the GNU General Public License as published by  *
+the Free Software Foundation; either version 2 of the License, or     *
+(at your option) any later version.                                   *
+
+**************************************************************************
+%End
+
+%TypeHeaderCode
+#include "qgsprocessingregistry.h"
+%End
+  public:
+
+    QString displayName;
+
+    QIcon icon;
+};
+
+
 class QgsProcessingRegistry : QObject
 {
 %Docstring(signature="appended")
@@ -78,6 +102,16 @@ Returns a matching provider by provider ID.
 Returns a list of all available algorithms from registered providers.
 
 .. seealso:: :py:func:`algorithmById`
+%End
+
+    QgsProcessingAlgorithmInformation algorithmInformation( const QString &id ) const;
+%Docstring
+Returns basic algorithm information for the algorithm with matching ID.
+
+This method uses an internal cache to ensure that information is quickly
+returned and is suitable for calling many times.
+
+.. versionadded:: 3.32
 %End
 
     const QgsProcessingAlgorithm *algorithmById( const QString &id ) const;

diff --git a/src/core/processing/qgsprocessingregistry.cpp b/src/core/processing/qgsprocessingregistry.cpp
@@ -116,6 +116,13 @@ bool QgsProcessingRegistry::addProvider( QgsProcessingProvider *provider )
 
   provider->setParent( this );
   mProviders[ provider->id()] = provider;
+
+  mCachedInformation.clear();
+  connect( provider, &QgsProcessingProvider::algorithmsLoaded, this, [this]
+  {
+    mCachedInformation.clear();
+  } );
+
   emit providerAdded( provider->id() );
   return true;
 }
@@ -133,6 +140,9 @@ bool QgsProcessingRegistry::removeProvider( QgsProcessingProvider *provider )
   provider->unload();
 
   delete mProviders.take( id );
+
+  mCachedInformation.clear();
+
   emit providerRemoved( id );
   return true;
 }
@@ -159,6 +169,22 @@ QList< const QgsProcessingAlgorithm * > QgsProcessingRegistry::algorithms() cons
   return algs;
 }
 
+QgsProcessingAlgorithmInformation QgsProcessingRegistry::algorithmInformation( const QString &id ) const
+{
+  const auto it = mCachedInformation.constFind( id );
+  if ( it != mCachedInformation.constEnd() )
+    return *it;
+
+  QgsProcessingAlgorithmInformation info;
+  if ( const QgsProcessingAlgorithm *algorithm = algorithmById( id ) )
+  {
+    info.displayName = algorithm->displayName();
+    info.icon = algorithm->icon();
+  }
+  mCachedInformation.insert( id, info );
+  return info;
+}
+
 const QgsProcessingAlgorithm *QgsProcessingRegistry::algorithmById( const QString &constId ) const
 {
   // allow mapping of algorithm via registered algorithm aliases

diff --git a/src/core/processing/qgsprocessingregistry.h b/src/core/processing/qgsprocessingregistry.h
@@ -26,6 +26,18 @@
 class QgsProcessingParameterType;
 class QgsProcessingAlgorithmConfigurationWidgetFactory;
 
+class CORE_EXPORT QgsProcessingAlgorithmInformation
+{
+  public:
+
+    //! Algorithm display name
+    QString displayName;
+
+    //! Algorithm icon
+    QIcon icon;
+};
+
+
 /**
  * \class QgsProcessingRegistry
  * \ingroup core
@@ -95,6 +107,16 @@ class CORE_EXPORT QgsProcessingRegistry : public QObject
      */
     QList< const QgsProcessingAlgorithm *> algorithms() const;
 
+    /**
+     * Returns basic algorithm information for the algorithm with matching ID.
+     *
+     * This method uses an internal cache to ensure that information is quickly
+     * returned and is suitable for calling many times.
+     *
+     * \since QGIS 3.32
+     */
+    QgsProcessingAlgorithmInformation algorithmInformation( const QString &id ) const;
+
     /**
      * Finds an algorithm by its ID. If no matching algorithm is found, NULLPTR
      * is returned.
@@ -215,9 +237,13 @@ class CORE_EXPORT QgsProcessingRegistry : public QObject
 
     QMap< QString, QString > mAlgorithmAliases;
 
+    mutable QMap< QString, QgsProcessingAlgorithmInformation > mCachedInformation;
+
 #ifdef SIP_RUN
     QgsProcessingRegistry( const QgsProcessingRegistry &other );
 #endif
+
+    friend class TestQgsProcessing;
 };
 
 #endif // QGSPROCESSINGREGISTRY_H

diff --git a/tests/src/analysis/testqgsprocessing.cpp b/tests/src/analysis/testqgsprocessing.cpp
@@ -1693,6 +1693,10 @@ void TestQgsProcessing::algorithm()
   QVERIFY( !p->algorithms().empty() );
 
   QgsProcessingRegistry r;
+
+  QgsProcessingAlgorithmInformation info = r.algorithmInformation( QStringLiteral( "p1:alg1" ) );
+  QVERIFY( info.displayName.isEmpty() );
+
   QVERIFY( r.addProvider( p ) );
   QCOMPARE( r.algorithms().size(), 2 );
   QVERIFY( r.algorithms().contains( p->algorithm( "alg1" ) ) );
@@ -1704,6 +1708,13 @@ void TestQgsProcessing::algorithm()
   QVERIFY( !r.algorithmById( "p1:alg3" ) );
   QVERIFY( !r.algorithmById( "px:alg1" ) );
 
+  info = r.algorithmInformation( QStringLiteral( "p1:alg1" ) );
+  QCOMPARE( info.displayName, QStringLiteral( "alg1" ) );
+  info = r.algorithmInformation( QStringLiteral( "p1:alg2" ) );
+  QCOMPARE( info.displayName, QStringLiteral( "alg2" ) );
+  info = r.algorithmInformation( QStringLiteral( "p1:alg3" ) );
+  QVERIFY( info.displayName.isEmpty() );
+
   // alias support
   QVERIFY( !r.algorithmById( QStringLiteral( "fake:fakealg" ) ) );
   r.addAlgorithmAlias( QStringLiteral( "fake:fakealg" ), QStringLiteral( "nope:none" ) );
@@ -1739,7 +1750,15 @@ void TestQgsProcessing::algorithm()
   DummyProvider *p3 = new DummyProvider( "p3" );
   QVERIFY( p3->algorithms().isEmpty() );
   QVERIFY( r.addProvider( p3 ) );
+  QVERIFY( r.mCachedInformation.empty() );
   QCOMPARE( p3->algorithms().size(), 2 );
+
+  info = r.algorithmInformation( QStringLiteral( "p3:alg2" ) );
+  QCOMPARE( info.displayName, QStringLiteral( "alg2" ) );
+
+  // a provider refresh should clear the registry's cache
+  p3->refreshAlgorithms();
+  QVERIFY( r.mCachedInformation.empty() );
 }
 
 void TestQgsProcessing::features()