/// <summary>
/// Performs join propagation.
/// </summary>
/// <returns>Changes propagated to the current join node in the update mapping view.</returns>
internal ChangeNode Propagate()
{
// Construct an empty change node for the result
ChangeNode result = Propagator.BuildChangeNode(m_joinExpression);
// Gather all keys involved in the join
JoinDictionary leftDeletes = ProcessKeys(m_left.Deleted, m_leftKeySelectors);
JoinDictionary leftInserts = ProcessKeys(m_left.Inserted, m_leftKeySelectors);
JoinDictionary rightDeletes = ProcessKeys(m_right.Deleted, m_rightKeySelectors);
JoinDictionary rightInserts = ProcessKeys(m_right.Inserted, m_rightKeySelectors);
var allKeys = leftDeletes.Keys
.Concat(leftInserts.Keys)
.Concat(rightDeletes.Keys)
.Concat(rightInserts.Keys)
.Distinct(m_parent.UpdateTranslator.KeyComparer);
// Perform propagation one key at a time
foreach (CompositeKey key in allKeys)
{
Propagate(key, result, leftDeletes, leftInserts, rightDeletes, rightInserts);
}
// Construct a new placeholder (see ChangeNode.Placeholder) for the join result node.
result.Placeholder = CreateResultTuple(Tuple.Create((CompositeKey)null, m_left.Placeholder), Tuple.Create((CompositeKey)null, m_right.Placeholder), result);
return(result);
}
/// <summary>
/// Produces a hash table of all instances and processes join keys, adding them to the list
/// of keys handled by this node.
/// </summary>
/// <param name="instances">List of instances (whether delete or insert) for this node.</param>
/// <param name="keySelectors">Selectors for key components.</param>
/// <returns>A map from join keys to instances.</returns>
private JoinDictionary ProcessKeys(IEnumerable <PropagatorResult> instances, ReadOnlyCollection <DbExpression> keySelectors)
{
// Dictionary uses the composite key on both sides. This is because the composite key, in addition
// to supporting comparison, maintains some context information (e.g., source of a value in the
// state manager).
var hash = new JoinDictionary(m_parent.UpdateTranslator.KeyComparer);
foreach (PropagatorResult instance in instances)
{
CompositeKey key = ExtractKey(instance, keySelectors, m_parent);
hash[key] = Tuple.Create(key, instance);
}
return(hash);
}
/// <summary>
/// Propagate all changes associated with a particular join key.
/// </summary>
/// <param name="key">Key.</param>
/// <param name="result">Resulting changes are added to this result.</param>
private void Propagate(CompositeKey key, ChangeNode result, JoinDictionary leftDeletes, JoinDictionary leftInserts,
JoinDictionary rightDeletes, JoinDictionary rightInserts)
{
// Retrieve changes associates with this join key
Tuple <CompositeKey, PropagatorResult> leftInsert = null;
Tuple <CompositeKey, PropagatorResult> leftDelete = null;
Tuple <CompositeKey, PropagatorResult> rightInsert = null;
Tuple <CompositeKey, PropagatorResult> rightDelete = null;
Ops input = Ops.Nothing;
if (leftInserts.TryGetValue(key, out leftInsert))
{
input |= Ops.LeftInsert;
}
if (leftDeletes.TryGetValue(key, out leftDelete))
{
input |= Ops.LeftDelete;
}
if (rightInserts.TryGetValue(key, out rightInsert))
{
input |= Ops.RightInsert;
}
if (rightDeletes.TryGetValue(key, out rightDelete))
{
input |= Ops.RightDelete;
}
// Get propagation rules for the changes
Ops insertRule = m_insertRules[input];
Ops deleteRule = m_deleteRules[input];
if (Ops.Unsupported == insertRule || Ops.Unsupported == deleteRule)
{
// If no propagation rules are defined, it suggests an invalid workload (e.g.
// a required entity or relationship is missing). In general, such exceptions
// should be caught by the RelationshipConstraintValidator, but we defensively
// check for problems here regardless. For instance, a 0..1:1..1 self-assocation
// implied a stronger constraint that cannot be checked by RelationshipConstraintValidator.
// First gather state entries contributing to the problem
List <IEntityStateEntry> stateEntries = new List <IEntityStateEntry>();
Action <Tuple <CompositeKey, PropagatorResult> > addStateEntries = (r) =>
{
if (r != null)
{
stateEntries.AddRange(SourceInterpreter.GetAllStateEntries(r.Item2, this.m_parent.m_updateTranslator,
this.m_parent.m_table));
}
};
addStateEntries(leftInsert);
addStateEntries(leftDelete);
addStateEntries(rightInsert);
addStateEntries(rightDelete);
throw EntityUtil.Update(Strings.Update_InvalidChanges, null, stateEntries);
}
// Where needed, substitute null/unknown placeholders. In some of the join propagation
// rules, we handle the case where a side of the join is 'unknown', or where one side
// of a join is comprised of an record containing only nulls. For instance, we may update
// only one extent appearing in a row of a table (unknown), or; we may insert only
// the left hand side of a left outer join, in which case the right hand side is 'null'.
if (0 != (Ops.LeftUnknown & insertRule))
{
leftInsert = Tuple.Create(key, LeftPlaceholder(key, PopulateMode.Unknown));
}
if (0 != (Ops.LeftUnknown & deleteRule))
{
leftDelete = Tuple.Create(key, LeftPlaceholder(key, PopulateMode.Unknown));
}
if (0 != (Ops.RightNullModified & insertRule))
{
rightInsert = Tuple.Create(key, RightPlaceholder(key, PopulateMode.NullModified));
}
else if (0 != (Ops.RightNullPreserve & insertRule))
{
rightInsert = Tuple.Create(key, RightPlaceholder(key, PopulateMode.NullPreserve));
}
else if (0 != (Ops.RightUnknown & insertRule))
{
rightInsert = Tuple.Create(key, RightPlaceholder(key, PopulateMode.Unknown));
}
if (0 != (Ops.RightNullModified & deleteRule))
{
rightDelete = Tuple.Create(key, RightPlaceholder(key, PopulateMode.NullModified));
}
else if (0 != (Ops.RightNullPreserve & deleteRule))
{
rightDelete = Tuple.Create(key, RightPlaceholder(key, PopulateMode.NullPreserve));
}
else if (0 != (Ops.RightUnknown & deleteRule))
{
rightDelete = Tuple.Create(key, RightPlaceholder(key, PopulateMode.Unknown));
}
// Populate elements in join output
if (null != leftInsert && null != rightInsert)
{
result.Inserted.Add(CreateResultTuple(leftInsert, rightInsert, result));
}
if (null != leftDelete && null != rightDelete)
{
result.Deleted.Add(CreateResultTuple(leftDelete, rightDelete, result));
}
}
/// <summary>
/// Produces a hash table of all instances and processes join keys, adding them to the list
/// of keys handled by this node.
/// </summary>
/// <param name="instances">List of instances (whether delete or insert) for this node.</param>
/// <param name="keySelectors">Selectors for key components.</param>
/// <returns>A map from join keys to instances.</returns>
private JoinDictionary ProcessKeys(IEnumerable<PropagatorResult> instances, ReadOnlyCollection<DbExpression> keySelectors)
{
// Dictionary uses the composite key on both sides. This is because the composite key, in addition
// to supporting comparison, maintains some context information (e.g., source of a value in the
// state manager).
var hash = new JoinDictionary(m_parent.UpdateTranslator.KeyComparer);
foreach (PropagatorResult instance in instances)
{
CompositeKey key = ExtractKey(instance, keySelectors, m_parent);
hash[key] = Tuple.Create(key, instance);
}
return hash;
}
/// <summary>
/// Propagate all changes associated with a particular join key.
/// </summary>
/// <param name="key">Key.</param>
/// <param name="result">Resulting changes are added to this result.</param>
private void Propagate(CompositeKey key, ChangeNode result, JoinDictionary leftDeletes, JoinDictionary leftInserts,
JoinDictionary rightDeletes, JoinDictionary rightInserts)
{
// Retrieve changes associates with this join key
Tuple<CompositeKey, PropagatorResult> leftInsert = null;
Tuple<CompositeKey, PropagatorResult> leftDelete = null;
Tuple<CompositeKey, PropagatorResult> rightInsert = null;
Tuple<CompositeKey, PropagatorResult> rightDelete = null;
Ops input = Ops.Nothing;
if (leftInserts.TryGetValue(key, out leftInsert)) { input |= Ops.LeftInsert; }
if (leftDeletes.TryGetValue(key, out leftDelete)) { input |= Ops.LeftDelete; }
if (rightInserts.TryGetValue(key, out rightInsert)) { input |= Ops.RightInsert; }
if (rightDeletes.TryGetValue(key, out rightDelete)) { input |= Ops.RightDelete; }
// Get propagation rules for the changes
Ops insertRule = m_insertRules[input];
Ops deleteRule = m_deleteRules[input];
if (Ops.Unsupported == insertRule || Ops.Unsupported == deleteRule)
{
// If no propagation rules are defined, it suggests an invalid workload (e.g.
// a required entity or relationship is missing). In general, such exceptions
// should be caught by the RelationshipConstraintValidator, but we defensively
// check for problems here regardless. For instance, a 0..1:1..1 self-assocation
// implied a stronger constraint that cannot be checked by RelationshipConstraintValidator.
// First gather state entries contributing to the problem
List<IEntityStateEntry> stateEntries = new List<IEntityStateEntry>();
Action<Tuple<CompositeKey, PropagatorResult>> addStateEntries = (r) =>
{
if (r != null)
{
stateEntries.AddRange(SourceInterpreter.GetAllStateEntries(r.Item2, this.m_parent.m_updateTranslator,
this.m_parent.m_table));
}
};
addStateEntries(leftInsert);
addStateEntries(leftDelete);
addStateEntries(rightInsert);
addStateEntries(rightDelete);
throw EntityUtil.Update(Strings.Update_InvalidChanges, null, stateEntries);
}
// Where needed, substitute null/unknown placeholders. In some of the join propagation
// rules, we handle the case where a side of the join is 'unknown', or where one side
// of a join is comprised of an record containing only nulls. For instance, we may update
// only one extent appearing in a row of a table (unknown), or; we may insert only
// the left hand side of a left outer join, in which case the right hand side is 'null'.
if (0 != (Ops.LeftUnknown & insertRule))
{
leftInsert = Tuple.Create(key, LeftPlaceholder(key, PopulateMode.Unknown));
}
if (0 != (Ops.LeftUnknown & deleteRule))
{
leftDelete = Tuple.Create(key, LeftPlaceholder(key, PopulateMode.Unknown));
}
if (0 != (Ops.RightNullModified & insertRule))
{
rightInsert = Tuple.Create(key, RightPlaceholder(key, PopulateMode.NullModified));
}
else if (0 != (Ops.RightNullPreserve & insertRule))
{
rightInsert = Tuple.Create(key, RightPlaceholder(key, PopulateMode.NullPreserve));
}
else if (0 != (Ops.RightUnknown & insertRule))
{
rightInsert = Tuple.Create(key, RightPlaceholder(key, PopulateMode.Unknown));
}
if (0 != (Ops.RightNullModified & deleteRule))
{
rightDelete = Tuple.Create(key, RightPlaceholder(key, PopulateMode.NullModified));
}
else if (0 != (Ops.RightNullPreserve & deleteRule))
{
rightDelete = Tuple.Create(key, RightPlaceholder(key, PopulateMode.NullPreserve));
}
else if (0 != (Ops.RightUnknown & deleteRule))
{
rightDelete = Tuple.Create(key, RightPlaceholder(key, PopulateMode.Unknown));
}
// Populate elements in join output
if (null != leftInsert && null != rightInsert)
{
result.Inserted.Add(CreateResultTuple(leftInsert, rightInsert, result));
}
if (null != leftDelete && null != rightDelete)
{
result.Deleted.Add(CreateResultTuple(leftDelete, rightDelete, result));
}
}