Fix for issue #31 now tested and it seems to be working

Civi/DataProcessor/DataFlow/CombinedDataFlow/CombinedDataFlow.php

@@ -8,10 +8,10 @@ namespace Civi\DataProcessor\DataFlow\CombinedDataFlow;
 
 use \Civi\DataProcessor\DataFlow\AbstractDataFlow;
 use \Civi\DataProcessor\DataFlow\EndOfFlowException;
+use Civi\DataProcessor\DataFlow\InvalidFlowException;
 use Civi\DataProcessor\DataFlow\MultipleDataFlows\DataFlowDescription;
 use Civi\DataProcessor\DataFlow\MultipleDataFlows\JoinInterface;
 use Civi\DataProcessor\DataFlow\MultipleDataFlows\MultipleSourceDataFlows;
-use Civi\DataProcessor\DataFlow\SqlDataFlow;
 use \Civi\DataProcessor\DataSpecification\DataSpecification;
 
 
@@ -66,6 +66,21 @@ class CombinedDataFlow extends AbstractDataFlow implements MultipleSourceDataFlo
     $this->sourceDataFlowDescriptions[] = $dataFlowDescription;
   }
 
+  /**
+   * Removes a source data flow
+   *
+   * @param \Civi\DataProcessor\DataFlow\MultipleDataFlows\DataFlowDescription $dataFlowDescription
+   * @return void
+   * @throws \Civi\DataProcessor\DataFlow\InvalidFlowException
+   */
+  public function removeSourceDataFlow(DataFlowDescription $dataFlowDescription) {
+    foreach($this->sourceDataFlowDescriptions as $idx => $sourceDataFlowDescription) {
+      if ($sourceDataFlowDescription === $dataFlowDescription) {
+        unset($this->sourceDataFlowDescriptions[$idx]);
+      }
+    }
+  }
+
   /**
    * @param \Civi\DataProcessor\FieldOutputHandler\AbstractFieldOutputHandler $outputFieldHandler[]
    */

Civi/DataProcessor/DataFlow/CombinedDataFlow/CombinedSqlDataFlow.php

@@ -60,6 +60,24 @@ class CombinedSqlDataFlow extends SqlDataFlow implements MultipleSourceDataFlows
     $this->sourceDataFlowDescriptions[] = $dataFlowDescription;
   }
 
+  /**
+   * Removes a source data flow
+   *
+   * @param \Civi\DataProcessor\DataFlow\MultipleDataFlows\DataFlowDescription $dataFlowDescription
+   * @return void
+   * @throws \Civi\DataProcessor\DataFlow\InvalidFlowException
+   */
+  public function removeSourceDataFlow(DataFlowDescription $dataFlowDescription) {
+    if (!$dataFlowDescription->getDataFlow() instanceof SqlDataFlow) {
+      throw new InvalidFlowException();
+    }
+    foreach($this->sourceDataFlowDescriptions as $idx => $sourceDataFlowDescription) {
+      if ($sourceDataFlowDescription === $dataFlowDescription) {
+        unset($this->sourceDataFlowDescriptions[$idx]);
+      }
+    }
+  }
+
   /**
    * Returns the Table part in the from statement.
    *

Civi/DataProcessor/DataFlow/CombinedDataFlow/UnionQueryDataFlow.php

@@ -46,6 +46,24 @@ class UnionQueryDataFlow extends SqlDataFlow implements MultipleSourceDataFlows
     $this->sourceDataFlowDescriptions[] = $dataFlowDescription;
   }
 
+  /**
+   * Removes a source data flow
+   *
+   * @param \Civi\DataProcessor\DataFlow\MultipleDataFlows\DataFlowDescription $dataFlowDescription
+   * @return void
+   * @throws \Civi\DataProcessor\DataFlow\InvalidFlowException
+   */
+  public function removeSourceDataFlow(DataFlowDescription $dataFlowDescription) {
+    if (!$dataFlowDescription->getDataFlow() instanceof SqlDataFlow) {
+      throw new InvalidFlowException();
+    }
+    foreach($this->sourceDataFlowDescriptions as $idx => $sourceDataFlowDescription) {
+      if ($sourceDataFlowDescription === $dataFlowDescription) {
+        unset($this->sourceDataFlowDescriptions[$idx]);
+      }
+    }
+  }
+
   public function getName() {
     return $this->name;
   }

Civi/DataProcessor/DataFlow/MultipleDataFlows/MultipleSourceDataFlows.php

@@ -16,4 +16,12 @@ interface MultipleSourceDataFlows {
    */
   public function addSourceDataFlow(DataFlowDescription $dataFlowDescription);
 
-}
\ No newline at end of file
+  /**
+   * Removes a source data flow
+   *
+   * @param \Civi\DataProcessor\DataFlow\MultipleDataFlows\DataFlowDescription $dataFlowDescription
+   * @return void
+   */
+  public function removeSourceDataFlow(DataFlowDescription $dataFlowDescription);
+
+}

Civi/DataProcessor/Source/Contact/ACLContactSource.php

@@ -7,6 +7,7 @@
 namespace Civi\DataProcessor\Source\Contact;
 
 use Civi\DataProcessor\DataFlow\MultipleDataFlows\DataFlowDescription;
+use Civi\DataProcessor\DataFlow\MultipleDataFlows\MultipleSourceDataFlows;
 use Civi\DataProcessor\DataFlow\MultipleDataFlows\PureSqlStatementJoin;
 use Civi\DataProcessor\DataFlow\SqlDataFlow\AndClause;
 use Civi\DataProcessor\DataFlow\SqlDataFlow\OrClause;
@@ -21,8 +22,10 @@ class ACLContactSource extends ContactSource {
    */
   protected $dataFlow;
 
-  public function initialize() {
+  protected $aclJoins = [];
+  protected $aclWhereClause = null;
 
+  public function initialize() {
     $tables = array();
     $whereTables = array();
     $where = \CRM_ACL_API::whereClause(\CRM_ACL_API::VIEW, $tables, $whereTables, NULL, FALSE, TRUE, FALSE);
@@ -48,12 +51,13 @@ class ACLContactSource extends ContactSource {
     $joinCriteria = str_replace('contact_a', $this->primaryDataFlow->getName(), $joinCriteria);
     $join = new PureSqlStatementJoin(' JOIN ' . $tableAndAlias . ' ON ' . $joinCriteria);
     $this->additionalDataFlowDescriptions[$tableAndAlias] = new DataFlowDescription($aclTable, $join);
+    $this->aclJoins[] = $tableAndAlias;
   }
 
   protected function addAclWhere($where) {
     $where = str_replace('contact_a', $this->primaryDataFlow->getName(), $where);
-    $clause = new PureSqlStatementClause($where);
-    $this->primaryDataFlow->addWhereClause($clause);
+    $this->aclWhereClause = new PureSqlStatementClause($where);
+    $this->primaryDataFlow->addWhereClause($this->aclWhereClause);
   }
 
   /**
@@ -98,10 +102,21 @@ class ACLContactSource extends ContactSource {
    * @return void
    */
   public function sourceLoadedFromCache() {
-    // reset the source. This completly looks up all the custom fields etc.. of this source
-    // ideally we only want to reset the aclWherePart.
-    $this->reset();
-    $this->initialize();
+    if ($this->primaryDataFlow && $this->aclWhereClause) {
+      $this->primaryDataFlow->removeWhereClause($this->aclWhereClause);
+    }
+    $this->aclWhereClause = null;
+    if (count($this->aclJoins)) {
+      foreach($this->aclJoins as $tableAndAlias) {
+        if (isset($this->additionalDataFlowDescriptions[$tableAndAlias])) {
+          if ($this->dataFlow && $this->dataFlow instanceof MultipleSourceDataFlows) {
+            $this->dataFlow->removeSourceDataFlow($this->additionalDataFlowDescriptions[$tableAndAlias]);
+          }
+          unset($this->additionalDataFlowDescriptions[$tableAndAlias]);
+        }
+      }
+      $this->aclJoins = [];
+    }
   }
 
 }