private static bool TryResolveConflicts <TItem>(this GraphNode <TItem> root, List <VersionConflictResult <TItem> > versionConflicts)
{
// now we walk the tree as often as it takes to determine
// which paths are accepted or rejected, based on conflicts occuring
// between cousin packages
var acceptedLibraries = Cache <TItem> .RentDictionary();
var patience = 1000;
var incomplete = true;
var tracker = Cache <TItem> .RentTracker();
Func <GraphNode <TItem>, bool> skipNode = null;
var centralTransitiveNodes = root.InnerNodes.Where(n => n.Item.IsCentralTransitive).ToList();
var hasCentralTransitiveDependencies = centralTransitiveNodes.Count > 0;
if (hasCentralTransitiveDependencies)
{
skipNode = (node) => { return(node.Item.IsCentralTransitive); };
}
while (incomplete && --patience != 0)
{
// Create a picture of what has not been rejected yet
root.ForEach(true, (node, state, context) => WalkTreeRejectNodesOfRejectedNodes(state, node, context), tracker, skipNode);
if (hasCentralTransitiveDependencies)
{
// Some of the central transitive nodes may be rejected now because their parents were rejected
// Reject them accordingly
root.RejectCentralTransitiveBecauseOfRejectedParents(tracker, centralTransitiveNodes);
}
// Inform tracker of ambiguity beneath nodes that are not resolved yet
root.ForEach(WalkState.Walking, (node, state, context) => WalkTreeMarkAmbiguousNodes(node, state, context), tracker);
if (hasCentralTransitiveDependencies)
{
DetectAndMarkAmbiguousCentralTransitiveDependencies(tracker, centralTransitiveNodes);
}
root.ForEach(true, (node, state, context) => WalkTreeAcceptOrRejectNodes(context, state, node), CreateState(tracker, acceptedLibraries));
incomplete = root.ForEachGlobalState(false, (node, state) => state || node.Disposition == Disposition.Acceptable);
tracker.Clear();
}
Cache <TItem> .ReleaseTracker(tracker);
root.ForEach((node, context) => WalkTreeDectectConflicts(node, context), CreateState(versionConflicts, acceptedLibraries));
Cache <TItem> .ReleaseDictionary(acceptedLibraries);
return(!incomplete);
}
private static void CheckCycleAndNearestWins(
this GraphNode <RemoteResolveResult> root,
List <DowngradeResult <RemoteResolveResult> > downgrades,
List <GraphNode <RemoteResolveResult> > cycles)
{
var workingDowngrades = RentDowngradesDictionary();
root.ForEach((node, context) => WalkTreeCheckCycleAndNearestWins(context, node), CreateState(cycles, workingDowngrades));
#if IS_DESKTOP || NETSTANDARD2_0
// Increase List size for items to be added, if too small
var requiredCapacity = downgrades.Count + workingDowngrades.Count;
if (downgrades.Capacity < requiredCapacity)
{
downgrades.Capacity = requiredCapacity;
}
#endif
foreach (var p in workingDowngrades)
{
downgrades.Add(new DowngradeResult <RemoteResolveResult>
{
DowngradedFrom = p.Key,
DowngradedTo = p.Value
});
}
ReleaseDowngradesDictionary(workingDowngrades);
}
private static bool TryResolveConflicts <TItem>(this GraphNode <TItem> root, List <VersionConflictResult <TItem> > versionConflicts)
{
// now we walk the tree as often as it takes to determine
// which paths are accepted or rejected, based on conflicts occuring
// between cousin packages
var acceptedLibraries = Cache <TItem> .RentDictionary();
var patience = 1000;
var incomplete = true;
var tracker = Cache <TItem> .RentTracker();
while (incomplete && --patience != 0)
{
// Create a picture of what has not been rejected yet
root.ForEach(true, (node, state, context) => WalkTreeRejectNodesOfRejectedNodes(state, node, context), tracker);
// Inform tracker of ambiguity beneath nodes that are not resolved yet
root.ForEach(WalkState.Walking, (node, state, context) => WalkTreeMarkAmbiguousNodes(node, state, context), tracker);
// Now mark unambiguous nodes as accepted or rejected
root.ForEach(true, (node, state, context) => WalkTreeAcceptOrRejectNodes(context, state, node), CreateState(tracker, acceptedLibraries));
incomplete = root.ForEachGlobalState(false, (node, state) => state || node.Disposition == Disposition.Acceptable);
tracker.Clear();
}
Cache <TItem> .ReleaseTracker(tracker);
root.ForEach((node, context) => WalkTreeDectectConflicts(node, context), CreateState(versionConflicts, acceptedLibraries));
Cache <TItem> .ReleaseDictionary(acceptedLibraries);
return(!incomplete);
}
public GraphNode <Library> Walk(string name, NuGetVersion version, NuGetFramework framework)
{
var key = new LibraryRange
{
Name = name,
VersionRange = new VersionRange(version)
};
var root = new GraphNode <Library>(key);
var resolvedItems = new Dictionary <LibraryRange, GraphItem <Library> >();
// Recurse through dependencies optimistically, asking resolvers for dependencies
// based on best match of each encountered dependency
root.ForEach(node =>
{
node.Item = Resolve(resolvedItems, node.Key, framework);
if (node.Item == null)
{
node.Disposition = Disposition.Rejected;
return;
}
foreach (var dependency in node.Item.Data.Dependencies)
{
// determine if a child dependency is eclipsed by
// a reference on the line leading to this point. this
// prevents cyclical dependencies, and also implements the
// "nearest wins" rule.
var eclipsed = false;
for (var scanNode = node;
scanNode != null && !eclipsed;
scanNode = scanNode.OuterNode)
{
eclipsed |= scanNode.Key.IsEclipsedBy(dependency.LibraryRange);
if (eclipsed)
{
throw new InvalidOperationException(string.Format("Circular dependency detected {0}.", GetChain(node, dependency)));
}
foreach (var sideNode in scanNode.InnerNodes)
{
eclipsed |= sideNode.Key.IsEclipsedBy(dependency.LibraryRange);
if (eclipsed)
{
break;
}
}
}
if (!eclipsed)
{
var innerNode = new GraphNode <Library>(dependency.LibraryRange)
{
OuterNode = node
};
node.InnerNodes.Add(innerNode);
}
}
});
return(root);
}
private static void CheckCycleAndNearestWins <TItem>(this GraphNode <TItem> root,
List <DowngradeResult <TItem> > downgrades,
List <GraphNode <TItem> > cycles)
{
// Cycle
// A -> B -> A (cycle)
// Downgrade
// A -> B -> C -> D 2.0 (downgrage)
// -> D 1.0
// Potential downgrade that turns out to not downgrade
// This should never happen in practice since B would have never been valid to begin with.
// A -> B -> C -> D 2.0
// -> D 1.0
// -> D 2.0
var workingDowngrades = new Dictionary <GraphNode <TItem>, GraphNode <TItem> >();
root.ForEach(node =>
{
if (node.Disposition == Disposition.Cycle)
{
cycles.Add(node);
// Remove this node from the tree so the nothing else evaluates this.
// This is ok since we have a parent pointer and we can still print the path
node.OuterNode.InnerNodes.Remove(node);
return;
}
if (node.Disposition != Disposition.PotentiallyDowngraded)
{
return;
}
// REVIEW: This could probably be done in a single pass where we keep track
// of what is nearer as we walk down the graph (BFS)
for (var n = node.OuterNode; n != null; n = n.OuterNode)
{
foreach (var sideNode in n.InnerNodes)
{
if (sideNode != node && StringComparer.OrdinalIgnoreCase.Equals(sideNode.Key.Name, node.Key.Name))
{
// Nodes that have no version range should be ignored as potential downgrades e.g. framework reference
if (sideNode.Key.VersionRange != null &&
node.Key.VersionRange != null &&
!RemoteDependencyWalker.IsGreaterThanOrEqualTo(sideNode.Key.VersionRange, node.Key.VersionRange))
{
workingDowngrades[node] = sideNode;
}
else
{
workingDowngrades.Remove(node);
}
}
}
}
// Remove this node from the tree so the nothing else evaluates this.
// This is ok since we have a parent pointer and we can still print the path
node.OuterNode.InnerNodes.Remove(node);
});
downgrades.AddRange(workingDowngrades.Select(p => new DowngradeResult <TItem>
{
DowngradedFrom = p.Key,
DowngradedTo = p.Value
}));
}
private static bool TryResolveConflicts <TItem>(this GraphNode <TItem> root, List <VersionConflictResult <TItem> > versionConflicts)
{
// now we walk the tree as often as it takes to determine
// which paths are accepted or rejected, based on conflicts occuring
// between cousin packages
var acceptedLibraries = new Dictionary <string, GraphNode <TItem> >(StringComparer.OrdinalIgnoreCase);
var patience = 1000;
var incomplete = true;
while (incomplete && --patience != 0)
{
// Create a picture of what has not been rejected yet
var tracker = new Tracker <TItem>();
root.ForEach(true, (node, state) =>
{
if (!state ||
node.Disposition == Disposition.Rejected)
{
// Mark all nodes as rejected if they aren't already marked
node.Disposition = Disposition.Rejected;
return(false);
}
tracker.Track(node.Item);
return(true);
});
// Inform tracker of ambiguity beneath nodes that are not resolved yet
// between:
// a1->b1->d1->x1
// a1->c1->d2->z1
// first attempt
// d1/d2 are considered disputed
// x1 and z1 are considered ambiguous
// d1 is rejected
// second attempt
// d1 is rejected, d2 is accepted
// x1 is no longer seen, and z1 is not ambiguous
// z1 is accepted
root.ForEach(WalkState.Walking, (node, state) =>
{
if (node.Disposition == Disposition.Rejected)
{
return(WalkState.Rejected);
}
if (state == WalkState.Walking &&
tracker.IsDisputed(node.Item))
{
return(WalkState.Ambiguous);
}
if (state == WalkState.Ambiguous)
{
tracker.MarkAmbiguous(node.Item);
}
return(state);
});
// Now mark unambiguous nodes as accepted or rejected
root.ForEach(true, (node, state) =>
{
if (!state ||
node.Disposition == Disposition.Rejected)
{
return(false);
}
if (tracker.IsAmbiguous(node.Item))
{
return(false);
}
if (node.Disposition == Disposition.Acceptable)
{
if (tracker.IsBestVersion(node.Item))
{
node.Disposition = Disposition.Accepted;
acceptedLibraries[node.Key.Name] = node;
}
else
{
node.Disposition = Disposition.Rejected;
}
}
return(node.Disposition == Disposition.Accepted);
});
incomplete = false;
root.ForEach(node => incomplete |= node.Disposition == Disposition.Acceptable);
}
root.ForEach(node =>
{
if (node.Disposition != Disposition.Accepted)
{
return;
}
// For all accepted nodes, find dependencies that aren't satisfied by the version
// of the package that we have selected
foreach (var childNode in node.InnerNodes)
{
GraphNode <TItem> acceptedNode;
if (acceptedLibraries.TryGetValue(childNode.Key.Name, out acceptedNode) &&
childNode != acceptedNode &&
childNode.Key.VersionRange != null &&
acceptedNode.Item.Key.Version != null)
{
var acceptedType = LibraryDependencyTargetUtils.Parse(acceptedNode.Item.Key.Type);
var childType = childNode.Key.TypeConstraint;
// Check the type constraints, if there is any overlap check for conflict
if ((childType & acceptedType) != LibraryDependencyTarget.None)
{
var versionRange = childNode.Key.VersionRange;
var checkVersion = acceptedNode.Item.Key.Version;
if (!versionRange.Satisfies(checkVersion))
{
versionConflicts.Add(new VersionConflictResult <TItem>
{
Selected = acceptedNode,
Conflicting = childNode
});
}
}
}
}
});
return(!incomplete);
}
private static void CheckCycleAndNearestWins(
this GraphNode <RemoteResolveResult> root,
List <DowngradeResult <RemoteResolveResult> > downgrades,
List <GraphNode <RemoteResolveResult> > cycles)
{
// Cycle:
//
// A -> B -> A (cycle)
//
// Downgrade:
//
// A -> B -> C -> D 2.0 (downgrade)
// -> D 1.0
//
// Potential downgrades that turns out to not be downgrades:
//
// 1. This should never happen in practice since B would have never been valid to begin with.
//
// A -> B -> C -> D 2.0
// -> D 1.0
// -> D 2.0
//
// 2. This occurs if none of the sources have version C 1.0 so C 1.0 is bumped up to C 2.0.
//
// A -> B -> C 2.0
// -> C 1.0
var workingDowngrades = new Dictionary <GraphNode <RemoteResolveResult>, GraphNode <RemoteResolveResult> >();
root.ForEach(node =>
{
if (node.Disposition == Disposition.Cycle)
{
cycles.Add(node);
// Remove this node from the tree so the nothing else evaluates this.
// This is ok since we have a parent pointer and we can still print the path
node.OuterNode.InnerNodes.Remove(node);
return;
}
if (node.Disposition != Disposition.PotentiallyDowngraded)
{
return;
}
// REVIEW: This could probably be done in a single pass where we keep track
// of what is nearer as we walk down the graph (BFS)
for (var n = node.OuterNode; n != null; n = n.OuterNode)
{
foreach (var sideNode in n.InnerNodes)
{
if (sideNode != node && StringComparer.OrdinalIgnoreCase.Equals(sideNode.Key.Name, node.Key.Name))
{
// Nodes that have no version range should be ignored as potential downgrades e.g. framework reference
if (sideNode.Key.VersionRange != null &&
node.Key.VersionRange != null &&
!RemoteDependencyWalker.IsGreaterThanOrEqualTo(sideNode.Key.VersionRange, node.Key.VersionRange))
{
// Is the resolved version actually within node's version range? This happen if there
// was a different request for a lower version of the library than this version range
// allows but no matching library was found, so the library is bumped up into this
// version range.
var resolvedVersion = sideNode?.Item?.Data?.Match?.Library?.Version;
if (resolvedVersion != null && node.Key.VersionRange.Satisfies(resolvedVersion))
{
continue;
}
workingDowngrades[node] = sideNode;
}
else
{
workingDowngrades.Remove(node);
}
}
}
}
// Remove this node from the tree so the nothing else evaluates this.
// This is ok since we have a parent pointer and we can still print the path
node.OuterNode.InnerNodes.Remove(node);
});
downgrades.AddRange(workingDowngrades.Select(p => new DowngradeResult <RemoteResolveResult>
{
DowngradedFrom = p.Key,
DowngradedTo = p.Value
}));
}
public static bool TryResolveConflicts <TItem>(this GraphNode <TItem> root)
{
// now we walk the tree as often as it takes to determine
// which paths are accepted or rejected, based on conflicts occuring
// between cousin packages
var patience = 1000;
var incomplete = true;
while (incomplete && --patience != 0)
{
// Create a picture of what has not been rejected yet
var tracker = new Tracker <TItem>();
root.ForEach(true, (node, state) =>
{
if (!state || node.Disposition == Disposition.Rejected)
{
// Mark all nodes as rejected if they aren't already marked
node.Disposition = Disposition.Rejected;
return(false);
}
tracker.Track(node.Item);
return(true);
});
// Inform tracker of ambiguity beneath nodes that are not resolved yet
// between:
// a1->b1->d1->x1
// a1->c1->d2->z1
// first attempt
// d1/d2 are considered disputed
// x1 and z1 are considered ambiguous
// d1 is rejected
// second attempt
// d1 is rejected, d2 is accepted
// x1 is no longer seen, and z1 is not ambiguous
// z1 is accepted
root.ForEach(WalkState.Walking, (node, state) =>
{
if (node.Disposition == Disposition.Rejected)
{
return(WalkState.Rejected);
}
if (state == WalkState.Walking && tracker.IsDisputed(node.Item))
{
return(WalkState.Ambiguous);
}
if (state == WalkState.Ambiguous)
{
tracker.MarkAmbiguous(node.Item);
}
return(state);
});
// Now mark unambiguous nodes as accepted or rejected
root.ForEach(true, (node, state) =>
{
if (!state || node.Disposition == Disposition.Rejected)
{
return(false);
}
if (tracker.IsAmbiguous(node.Item))
{
return(false);
}
if (node.Disposition == Disposition.Acceptable)
{
node.Disposition = tracker.IsBestVersion(node.Item) ? Disposition.Accepted : Disposition.Rejected;
}
return(node.Disposition == Disposition.Accepted);
});
incomplete = false;
root.ForEach(node => incomplete |= node.Disposition == Disposition.Acceptable);
}
return(!incomplete);
}
public GraphNode <ResolveResult> Walk(string name, NuGetVersion version, NuGetFramework framework)
{
var key = new LibraryRange
{
Name = name,
VersionRange = new NuGetVersionRange(version)
};
var root = new GraphNode <ResolveResult>(key);
var resolvedItems = new Dictionary <LibraryRange, GraphItem <ResolveResult> >();
// Recurse through dependencies optimistically, asking resolvers for dependencies
// based on best match of each encountered dependency
root.ForEach(node =>
{
node.Item = Resolve(resolvedItems, node.Key, framework);
if (node.Item == null)
{
node.Disposition = Disposition.Rejected;
return;
}
foreach (var dependency in node.Item.Data.LibraryDescription.Dependencies)
{
// determine if a child dependency is eclipsed by
// a reference on the line leading to this point. this
// prevents cyclical dependencies, and also implements the
// "nearest wins" rule.
var eclipsed = false;
for (var scanNode = node;
scanNode != null && !eclipsed;
scanNode = scanNode.OuterNode)
{
eclipsed |= string.Equals(
scanNode.Key.Name,
dependency.Name,
StringComparison.OrdinalIgnoreCase);
if (eclipsed)
{
break;
}
foreach (var sideNode in scanNode.InnerNodes)
{
eclipsed |= string.Equals(
sideNode.Key.Name,
dependency.Name,
StringComparison.OrdinalIgnoreCase);
if (eclipsed)
{
break;
}
}
}
if (!eclipsed)
{
var innerNode = new GraphNode <ResolveResult>(dependency.LibraryRange)
{
OuterNode = node
};
node.InnerNodes.Add(innerNode);
}
}
});
return(root);
}
