/// <summary>
/// Packages occuring first are more likely to get their preferred version, for this
/// reason installed packages should go first, then targets.
/// </summary>
private static int GetTreeFlattenPriority(string id, PackageResolverContext context)
{
// Targets go in the middle
// this needs to be checked first since the target may also exist in the installed packages (upgrade)
if (context.TargetIds.Contains(id, StringComparer.OrdinalIgnoreCase))
{
return(1);
}
// Installed packages go first
if (context.PackagesConfig.Select(package => package.PackageIdentity.Id).Contains(id, StringComparer.OrdinalIgnoreCase))
{
return(0);
}
// New dependencies go last
return(2);
}
/// <summary>
/// Resolve a package closure
/// </summary>
public IEnumerable <PackageIdentity> Resolve(PackageResolverContext context, CancellationToken token)
{
var stopWatch = new Stopwatch();
token.ThrowIfCancellationRequested();
if (context == null)
{
throw new ArgumentNullException(nameof(context));
}
// validation
foreach (var requiredId in context.RequiredPackageIds)
{
if (!context.AvailablePackages.Any(p => StringComparer.OrdinalIgnoreCase.Equals(p.Id, requiredId)))
{
throw new NuGetResolverInputException(String.Format(CultureInfo.CurrentCulture, Strings.MissingDependencyInfo, requiredId));
}
}
// convert the available packages into ResolverPackages
var resolverPackages = new List <ResolverPackage>();
// pre-process the available packages to remove any packages that can't possibly form part of a solution
var availablePackages = RemoveImpossiblePackages(context.AvailablePackages, context.RequiredPackageIds);
foreach (var package in availablePackages)
{
IEnumerable <PackageDependency> dependencies = null;
// clear out the dependencies if the behavior is set to ignore
if (context.DependencyBehavior == DependencyBehavior.Ignore)
{
dependencies = Enumerable.Empty <PackageDependency>();
}
else
{
dependencies = package.Dependencies ?? Enumerable.Empty <PackageDependency>();
}
resolverPackages.Add(new ResolverPackage(package.Id, package.Version, dependencies, package.Listed, false));
}
// Sort the packages to make this process as deterministic as possible
resolverPackages.Sort(PackageIdentityComparer.Default);
// Keep track of the ids we have added
var groupsAdded = new HashSet <string>(StringComparer.OrdinalIgnoreCase);
var grouped = new List <List <ResolverPackage> >();
// group the packages by id
foreach (var group in resolverPackages.GroupBy(e => e.Id, StringComparer.OrdinalIgnoreCase))
{
groupsAdded.Add(group.Key);
var curSet = group.ToList();
// add an absent package for non-targets
// being absent allows the resolver to throw it out if it is not needed
if (!context.RequiredPackageIds.Contains(group.Key, StringComparer.OrdinalIgnoreCase))
{
curSet.Add(new ResolverPackage(id: group.Key, version: null, dependencies: null, listed: true, absent: true));
}
grouped.Add(curSet);
}
// find all needed dependencies
var dependencyIds = resolverPackages.Where(e => e.Dependencies != null)
.SelectMany(e => e.Dependencies.Select(d => d.Id).Distinct(StringComparer.OrdinalIgnoreCase));
foreach (string depId in dependencyIds)
{
// packages which are unavailable need to be added as absent packages
// ex: if A -> B and B is not found anywhere in the source repositories we add B as absent
if (!groupsAdded.Contains(depId))
{
groupsAdded.Add(depId);
grouped.Add(new List <ResolverPackage>()
{
new ResolverPackage(id: depId, version: null, dependencies: null, listed: true, absent: true)
});
}
}
token.ThrowIfCancellationRequested();
// keep track of the best partial solution
var bestSolution = Enumerable.Empty <ResolverPackage>();
Action <IEnumerable <ResolverPackage> > diagnosticOutput = (partialSolution) =>
{
// store each solution as they pass through.
// the combination solver verifies that the last one returned is the best
bestSolution = partialSolution;
};
// Run solver
var comparer = new ResolverComparer(context.DependencyBehavior, context.PreferredVersions, context.TargetIds);
var sortedGroups = ResolverInputSort.TreeFlatten(grouped, context);
var solution = CombinationSolver <ResolverPackage> .FindSolution(
groupedItems : sortedGroups,
itemSorter : comparer,
shouldRejectPairFunc : ResolverUtility.ShouldRejectPackagePair,
diagnosticOutput : diagnosticOutput);
// check if a solution was found
if (solution != null)
{
var nonAbsentCandidates = solution.Where(c => !c.Absent);
if (nonAbsentCandidates.Any())
{
// topologically sort non absent packages
var sortedSolution = ResolverUtility.TopologicalSort(nonAbsentCandidates);
// Find circular dependency for topologically sorted non absent packages since it will help maintain cache of
// already processed packages
var circularReferences = ResolverUtility.FindFirstCircularDependency(sortedSolution);
if (circularReferences.Any())
{
// the resolver is able to handle circular dependencies, however we should throw here to keep these from happening
throw new NuGetResolverConstraintException(
String.Format(CultureInfo.CurrentCulture, Strings.CircularDependencyDetected,
String.Join(" => ", circularReferences.Select(package => $"{package.Id} {package.Version.ToNormalizedString()}"))));
}
// solution found!
stopWatch.Stop();
context.Log.LogMinimal(
string.Format(Strings.ResolverTotalTime, DatetimeUtility.ToReadableTimeFormat(stopWatch.Elapsed)));
return(sortedSolution.ToArray());
}
}
// no solution was found, throw an error with a diagnostic message
var message = ResolverUtility.GetDiagnosticMessage(bestSolution, context.AvailablePackages, context.PackagesConfig, context.TargetIds, context.PackageSources);
throw new NuGetResolverConstraintException(message);
}
/// <summary>
/// Resolve a package closure
/// </summary>
public IEnumerable<PackageIdentity> Resolve(PackageResolverContext context, CancellationToken token)
{
token.ThrowIfCancellationRequested();
if (context == null)
{
throw new ArgumentNullException(nameof(context));
}
// validation
foreach (var requiredId in context.RequiredPackageIds)
{
if (!context.AvailablePackages.Any(p => StringComparer.OrdinalIgnoreCase.Equals(p.Id, requiredId)))
{
throw new NuGetResolverInputException(String.Format(CultureInfo.CurrentCulture, Strings.MissingDependencyInfo, requiredId));
}
}
// convert the available packages into ResolverPackages
var resolverPackages = new List<ResolverPackage>();
// pre-process the available packages to remove any packages that can't possibly form part of a solution
var availablePackages = RemoveImpossiblePackages(context.AvailablePackages, context.RequiredPackageIds);
foreach (var package in availablePackages)
{
IEnumerable<PackageDependency> dependencies = null;
// clear out the dependencies if the behavior is set to ignore
if (context.DependencyBehavior == DependencyBehavior.Ignore)
{
dependencies = Enumerable.Empty<PackageDependency>();
}
else
{
dependencies = package.Dependencies ?? Enumerable.Empty<PackageDependency>();
}
resolverPackages.Add(new ResolverPackage(package.Id, package.Version, dependencies, package.Listed, false));
}
// Sort the packages to make this process as deterministic as possible
resolverPackages.Sort(PackageIdentityComparer.Default);
// Keep track of the ids we have added
var groupsAdded = new HashSet<string>(StringComparer.OrdinalIgnoreCase);
var grouped = new List<List<ResolverPackage>>();
// group the packages by id
foreach (var group in resolverPackages.GroupBy(e => e.Id, StringComparer.OrdinalIgnoreCase))
{
groupsAdded.Add(group.Key);
var curSet = group.ToList();
// add an absent package for non-targets
// being absent allows the resolver to throw it out if it is not needed
if (!context.RequiredPackageIds.Contains(group.Key, StringComparer.OrdinalIgnoreCase))
{
curSet.Add(new ResolverPackage(id: group.Key, version: null, dependencies: null, listed: true, absent: true));
}
grouped.Add(curSet);
}
// find all needed dependencies
var dependencyIds = resolverPackages.Where(e => e.Dependencies != null)
.SelectMany(e => e.Dependencies.Select(d => d.Id).Distinct(StringComparer.OrdinalIgnoreCase));
foreach (string depId in dependencyIds)
{
// packages which are unavailable need to be added as absent packages
// ex: if A -> B and B is not found anywhere in the source repositories we add B as absent
if (!groupsAdded.Contains(depId))
{
groupsAdded.Add(depId);
grouped.Add(new List<ResolverPackage>() { new ResolverPackage(id: depId, version: null, dependencies: null, listed: true, absent: true) });
}
}
token.ThrowIfCancellationRequested();
// keep track of the best partial solution
var bestSolution = Enumerable.Empty<ResolverPackage>();
Action<IEnumerable<ResolverPackage>> diagnosticOutput = (partialSolution) =>
{
// store each solution as they pass through.
// the combination solver verifies that the last one returned is the best
bestSolution = partialSolution;
};
// Run solver
var comparer = new ResolverComparer(context.DependencyBehavior, context.PreferredVersions, context.TargetIds);
var solution = CombinationSolver<ResolverPackage>.FindSolution(
groupedItems: grouped,
itemSorter: comparer,
shouldRejectPairFunc: ResolverUtility.ShouldRejectPackagePair,
diagnosticOutput: diagnosticOutput);
// check if a solution was found
if (solution != null)
{
var nonAbsentCandidates = solution.Where(c => !c.Absent);
if (nonAbsentCandidates.Any())
{
var circularReferences = ResolverUtility.FindCircularDependency(solution);
if (circularReferences.Any())
{
// the resolver is able to handle circular dependencies, however we should throw here to keep these from happening
throw new NuGetResolverConstraintException(
String.Format(CultureInfo.CurrentCulture, Strings.CircularDependencyDetected,
String.Join(" => ", circularReferences.Select(package => $"{package.Id} {package.Version.ToString()}"))));
}
// solution found!
var sortedSolution = ResolverUtility.TopologicalSort(nonAbsentCandidates);
return sortedSolution.ToArray();
}
}
// no solution was found, throw an error with a diagnostic message
var message = ResolverUtility.GetDiagnosticMessage(bestSolution, context.AvailablePackages, context.PackagesConfig, context.TargetIds);
throw new NuGetResolverConstraintException(message);
}
/// <summary>
/// Order package trees into a flattened list
///
/// Package Id (Parent count)
/// Iteration 1: A(0) -> B(1) -> D(2)
/// C(0) -> D(2)
/// [Select A]
///
/// Iteration 2: B(0) -> D(2)
/// C(0) -> D(2)
/// [Select B]
///
/// Iteration 2: C(0) -> D(1)
/// [Select C]
///
/// Result: A, B, C, D
/// </summary>
public static List <List <ResolverPackage> > TreeFlatten(List <List <ResolverPackage> > grouped, PackageResolverContext context)
{
var sorted = new List <List <ResolverPackage> >();
// find all package ids
var groupIds = grouped.Select(group => group.First().Id).ToList();
// find all dependencies for each id
var dependencies = grouped.Select(group => new SortedSet <string>(
group.SelectMany(g => g.Dependencies)
.Select(d => d.Id), StringComparer.OrdinalIgnoreCase))
.ToList();
// track all parents of an id
var parents = new Dictionary <string, SortedSet <string> >(StringComparer.OrdinalIgnoreCase);
for (int i = 0; i < grouped.Count; i++)
{
var parentsForId = new SortedSet <string>(StringComparer.OrdinalIgnoreCase);
for (int j = 0; j < grouped.Count; j++)
{
if (i != j && dependencies[j].Contains(groupIds[i]))
{
parentsForId.Add(groupIds[j]);
}
}
parents.Add(groupIds[i], parentsForId);
}
var idsToSort = new List <string>(groupIds);
var childrenOfLastId = new SortedSet <string>(StringComparer.OrdinalIgnoreCase);
// Loop through the package ids taking the best one each time
// and removing it from the parent list.
while (idsToSort.Count > 0)
{
// 1. Lowest number of parents remaining goes
// 2. Prefer children of the last id sorted next
// 3. Installed, target, then new package
// 4. Highest number of dependencies goes first
// 5. Fallback to string sort
var nextId = idsToSort.OrderBy(id => parents[id].Count)
.ThenBy(id => childrenOfLastId.Contains(id) ? 0 : 1)
.ThenBy(id => GetTreeFlattenPriority(id, context))
.ThenByDescending(id => parents.Values.Where(parentIds => parentIds.Contains(id)).Count())
.ThenBy(id => id, StringComparer.OrdinalIgnoreCase)
.First();
// Find the group for the best id
var nextGroup = grouped.Where(group => StringComparer.OrdinalIgnoreCase.Equals(group.First().Id, nextId)).Single();
sorted.Add(nextGroup);
childrenOfLastId.Clear();
// Remove the id from the parent list now that we have found a place for it
foreach (var childId in parents.Keys)
{
var parentIds = parents[childId];
if (parentIds.Remove(nextId))
{
childrenOfLastId.Add(childId);
}
}
// Complete the id
grouped.Remove(nextGroup);
idsToSort.Remove(nextId);
}
return(sorted);
}
