private bool DetermineRejection(ComposablePartDefinition definition, AtomicComposition parentAtomicComposition)
{
ChangeRejectedException exception = null;
// if there is no active atomic composition and rejection is disabled, there's no need to do any of the below
if (!EnsureRejection(parentAtomicComposition))
{
return(false);
}
using (var localAtomicComposition = new AtomicComposition(parentAtomicComposition))
{
// The part definition we're currently working on is treated optimistically
// as if we know it hasn't been rejected. This handles recursion, and if we
// later decide that it has been rejected we'll discard all nested progress so
// all side-effects of the mistake are erased.
//
// Note that this means that recursive failures that would be detected by the
// import engine are not discovered by rejection currently. Loops among
// prerequisites, runaway import chains involving factories, and prerequisites
// that cannot be fully satisfied still result in runtime errors. Doing
// otherwise would be possible but potentially expensive - and could be a v2
// improvement if deemed worthwhile.
UpdateAtomicCompositionQueryForPartEquals(localAtomicComposition,
definition, AtomicCompositionQueryState.TreatAsValidated);
var newPart = definition.CreatePart();
try
{
_importEngine.PreviewImports(newPart, localAtomicComposition);
// Reuse the partially-fleshed out part the next time we need a shared
// instance to keep the expense of pre-validation to a minimum. Note that
// _activatedParts holds references to both shared and non-shared parts.
// The non-shared parts will only be used for rejection purposes only but
// the shared parts will be handed out when requested via GetExports as
// well as be used for rejection purposes.
localAtomicComposition.AddCompleteActionAllowNull(() =>
{
using (_lock.LockStateForWrite())
{
if (!_activatedParts.ContainsKey(definition))
{
_activatedParts.Add(definition, new CatalogPart(newPart));
IDisposable newDisposablePart = newPart as IDisposable;
if (newDisposablePart != null)
{
_partsToDispose.Add(newDisposablePart);
}
}
}
});
// Success! Complete any recursive work that was conditioned on this part's validation
localAtomicComposition.Complete();
return(false);
}
catch (ChangeRejectedException ex)
{
exception = ex;
}
}
// If we've reached this point then this part has been rejected so we need to
// record the rejection in our parent composition or execute it immediately if
// one doesn't exist.
parentAtomicComposition.AddCompleteActionAllowNull(() =>
{
using (_lock.LockStateForWrite())
{
_rejectedParts.Add(definition);
}
CompositionTrace.PartDefinitionRejected(definition, exception);
});
if (parentAtomicComposition != null)
{
UpdateAtomicCompositionQueryForPartEquals(parentAtomicComposition,
definition, AtomicCompositionQueryState.TreatAsRejected);
}
return(true);
}
public void AtomicComposition_NestedQueries()
{
// This is a rather convoluted test that exercises the way AtomicComposition used to work to
// ensure consistency of the newer design
var key = new Object();
using (var contextA = new AtomicComposition())
{
SetQuery(contextA, key, (int parameter, Func <int, bool> parentQuery) =>
{
if (parameter == 22)
{
return(true);
}
if (parentQuery != null)
{
return(parentQuery(parameter));
}
return(false);
});
TestQuery(contextA, key, 22, true);
using (var contextB = new AtomicComposition(contextA))
{
TestQuery(contextB, key, 22, true);
SetQuery(contextB, key, (int parameter, Func <int, bool> parentQuery) =>
{
if (parentQuery != null)
{
return(!parentQuery(parameter));
}
Assert.False(true);
return(false);
});
TestQuery(contextB, key, 21, true);
TestQuery(contextB, key, 22, false);
using (var contextC = new AtomicComposition(contextB))
{
SetQuery(contextC, key, (int parameter, Func <int, bool> parentQuery) =>
{
if (parameter == 23)
{
return(true);
}
if (parentQuery != null)
{
return(!parentQuery(parameter));
}
Assert.False(true);
return(false);
});
TestQuery(contextC, key, 21, false);
TestQuery(contextC, key, 22, true);
TestQuery(contextC, key, 23, true);
contextC.Complete();
}
using (var contextD = new AtomicComposition(contextB))
{
SetQuery(contextD, key, (int parameter, Func <int, bool> parentQuery) =>
{
if (parentQuery != null)
{
return(parentQuery(parameter + 1));
}
Assert.False(true);
return(false);
});
TestQuery(contextD, key, 21, true);
TestQuery(contextD, key, 22, true);
TestQuery(contextD, key, 23, false);
// No complete
}
contextB.Complete();
}
TestQuery(contextA, key, 21, false);
TestQuery(contextA, key, 22, true);
TestQuery(contextA, key, 23, true);
contextA.Complete();
}
}
private void UpdateRejections(IEnumerable <ExportDefinition> changedExports, AtomicComposition atomicComposition)
{
using (var localAtomicComposition = new AtomicComposition(atomicComposition))
{
// Reconsider every part definition that has been previously
// rejected to see if any of them can be added back.
var affectedRejections = new HashSet <ComposablePartDefinition>();
ComposablePartDefinition[] rejectedParts;
using (_lock.LockStateForRead())
{
rejectedParts = _rejectedParts.ToArray();
}
foreach (var definition in rejectedParts)
{
if (QueryPartState(localAtomicComposition, definition) == AtomicCompositionQueryState.TreatAsValidated)
{
continue;
}
foreach (var import in definition.ImportDefinitions.Where(ImportEngine.IsRequiredImportForPreview))
{
if (changedExports.Any(export => import.IsConstraintSatisfiedBy(export)))
{
affectedRejections.Add(definition);
break;
}
}
}
UpdateAtomicCompositionQueryForPartInHashSet(localAtomicComposition,
affectedRejections, AtomicCompositionQueryState.NeedsTesting);
// Determine if any of the resurrectable parts is now available so that we can
// notify listeners of the exact changes to exports
var resurrectedExports = new List <ExportDefinition>();
foreach (var partDefinition in affectedRejections)
{
if (!IsRejected(partDefinition, localAtomicComposition))
{
// Notify listeners of the newly available exports and
// prepare to remove the rejected part from the list of rejections
resurrectedExports.AddRange(partDefinition.ExportDefinitions);
// Capture the local so that the closure below refers to the current definition
// in the loop and not the value of 'partDefinition' when the closure executes
var capturedPartDefinition = partDefinition;
localAtomicComposition.AddCompleteAction(() =>
{
using (_lock.LockStateForWrite())
{
_rejectedParts.Remove(capturedPartDefinition);
}
CompositionTrace.PartDefinitionResurrected(capturedPartDefinition);
});
}
}
// Notify anyone sourcing exports that the resurrected exports have appeared
if (resurrectedExports.Any())
{
OnExportsChanging(
new ExportsChangeEventArgs(resurrectedExports, Array.Empty <ExportDefinition>(), localAtomicComposition));
localAtomicComposition.AddCompleteAction(() => OnExportsChanged(
new ExportsChangeEventArgs(resurrectedExports, Array.Empty <ExportDefinition>(), null)));
}
localAtomicComposition.Complete();
}
}
public void Compose(CompositionBatch batch)
{
this.ThrowIfDisposed();
this.EnsureRunning();
Requires.NotNull(batch, "batch");
// Quick exit test can be done prior to cloning since it's just an optimization, not a
// change in behavior
if ((batch.PartsToAdd.Count == 0) && (batch.PartsToRemove.Count == 0))
{
return;
}
CompositionResult result = CompositionResult.SucceededResult;
// Clone the batch, so that the external changes wouldn't happen half-way thorugh compose
// NOTE : this does not guarantee the atomicity of cloning, which is not the goal anyway,
// rather the fact that all subsequent calls will deal with an unchanging batch
batch = new CompositionBatch(batch.PartsToAdd, batch.PartsToRemove);
var newParts = GetUpdatedPartsList(batch);
// Allow only recursive calls from the import engine to see the changes until
// they've been verified ...
using (var atomicComposition = new AtomicComposition())
{
// Don't allow reentrant calls to compose during previewing to prevent
// corrupted state.
if (this._currentlyComposing)
{
throw new InvalidOperationException(Strings.ReentrantCompose);
}
this._currentlyComposing = true;
try
{
// In the meantime recursive calls need to be able to see the list as well
atomicComposition.SetValue(this, newParts);
// Recompose any existing imports effected by the these changes first so that
// adapters, resurrected parts, etc. can all play their role in satisfying
// imports for added parts
this.Recompose(batch, atomicComposition);
// Ensure that required imports can be satisfied
foreach (ComposablePart part in batch.PartsToAdd)
{
// collect the result of previewing all the adds in the batch
try
{
this._importEngine.PreviewImports(part, atomicComposition);
}
catch (ChangeRejectedException ex)
{
result = result.MergeResult(new CompositionResult(ex.Errors));
}
}
result.ThrowOnErrors(atomicComposition);
// Complete the new parts since they passed previewing.`
using (this._lock.LockStateForWrite())
{
this._parts = newParts;
}
atomicComposition.Complete();
}
finally
{
this._currentlyComposing = false;
}
}
// Satisfy Imports
// - Satisfy imports on all newly added component parts
foreach (ComposablePart part in batch.PartsToAdd)
{
result = result.MergeResult(CompositionServices.TryInvoke(() =>
this._importEngine.SatisfyImports(part)));
}
// return errors
result.ThrowOnErrors();
}
public void Compose(CompositionBatch batch)
{
ThrowIfDisposed();
EnsureRunning();
Requires.NotNull(batch, nameof(batch));
// Quick exit test can be done prior to cloning since it's just an optimization, not a
// change in behavior
if ((batch.PartsToAdd.Count == 0) && (batch.PartsToRemove.Count == 0))
{
return;
}
CompositionResult result = CompositionResult.SucceededResult;
// Get updated parts list and a cloned batch
var newParts = GetUpdatedPartsList(ref batch);
// Allow only recursive calls from the import engine to see the changes until
// they've been verified ...
using (var atomicComposition = new AtomicComposition())
{
// Don't allow reentrant calls to compose during previewing to prevent
// corrupted state.
if (_currentlyComposing)
{
throw new InvalidOperationException(SR.ReentrantCompose);
}
_currentlyComposing = true;
try
{
// In the meantime recursive calls need to be able to see the list as well
atomicComposition.SetValue(this, newParts);
// Recompose any existing imports effected by the these changes first so that
// adapters, resurrected parts, etc. can all play their role in satisfying
// imports for added parts
Recompose(batch, atomicComposition);
// Ensure that required imports can be satisfied
foreach (ComposablePart part in batch.PartsToAdd)
{
// collect the result of previewing all the adds in the batch
try
{
ImportEngine.PreviewImports(part, atomicComposition);
}
catch (ChangeRejectedException ex)
{
result = result.MergeResult(new CompositionResult(ex.Errors));
}
}
result.ThrowOnErrors(atomicComposition);
// Complete the new parts since they passed previewing.`
using (_lock.LockStateForWrite())
{
_parts = newParts;
}
atomicComposition.Complete();
}
finally
{
_currentlyComposing = false;
}
}
// Satisfy Imports
// - Satisfy imports on all newly added component parts
foreach (ComposablePart part in batch.PartsToAdd)
{
result = result.MergeResult(CompositionServices.TryInvoke(() =>
ImportEngine.SatisfyImports(part)));
}
// return errors
result.ThrowOnErrors();
}
/// <summary>
/// Refreshes the <see cref="ComposablePartDefinition"/>s with the latest files in the directory that match
/// the searchPattern. If any files have been added they will be added to the catalog and if any files were
/// removed they will be removed from the catalog. For files that have been removed keep in mind that the
/// assembly cannot be unloaded from the process so <see cref="ComposablePartDefinition"/>s for those files
/// will simply be removed from the catalog.
///
/// Possible exceptions that can be thrown are any that <see cref="Directory.GetFiles(string, string)"/> or
/// <see cref="Assembly.Load(AssemblyName)"/> can throw.
/// </summary>
/// <exception cref="DirectoryNotFoundException">
/// The specified <paramref name="path"/> has been removed since object construction.
/// </exception>
public void Refresh()
{
this.ThrowIfDisposed();
Assumes.NotNull(this._loadedFiles);
List <Tuple <string, AssemblyCatalog> > catalogsToAdd;
List <Tuple <string, AssemblyCatalog> > catalogsToRemove;
ComposablePartDefinition[] addedDefinitions;
ComposablePartDefinition[] removedDefinitions;
object changeReferenceObject;
string[] afterFiles;
string[] beforeFiles;
while (true)
{
afterFiles = this.GetFiles();
using (new ReadLock(this._thisLock))
{
changeReferenceObject = this._loadedFiles;
beforeFiles = this._loadedFiles.ToArray();
}
this.DiffChanges(beforeFiles, afterFiles, out catalogsToAdd, out catalogsToRemove);
// Don't go any further if there's no work to do
if (catalogsToAdd.Count == 0 && catalogsToRemove.Count == 0)
{
return;
}
// Notify listeners to give them a preview before completeting the changes
addedDefinitions = catalogsToAdd
.SelectMany(cat => cat.Item2.Parts)
.ToArray <ComposablePartDefinition>();
removedDefinitions = catalogsToRemove
.SelectMany(cat => cat.Item2.Parts)
.ToArray <ComposablePartDefinition>();
using (var atomicComposition = new AtomicComposition())
{
var changingArgs = new ComposablePartCatalogChangeEventArgs(addedDefinitions, removedDefinitions, atomicComposition);
this.OnChanging(changingArgs);
// if the change went through then write the catalog changes
using (new WriteLock(this._thisLock))
{
if (changeReferenceObject != this._loadedFiles)
{
// Someone updated the list while we were diffing so we need to try the diff again
continue;
}
foreach (var catalogToAdd in catalogsToAdd)
{
this._assemblyCatalogs.Add(catalogToAdd.Item1, catalogToAdd.Item2);
this._catalogCollection.Add(catalogToAdd.Item2);
}
foreach (var catalogToRemove in catalogsToRemove)
{
this._assemblyCatalogs.Remove(catalogToRemove.Item1);
this._catalogCollection.Remove(catalogToRemove.Item2);
}
this._partsQuery = this._catalogCollection.AsQueryable().SelectMany(catalog => catalog.Parts);
this._loadedFiles = afterFiles.ToReadOnlyCollection();
// Lastly complete any changes added to the atomicComposition during the change event
atomicComposition.Complete();
// Break out of the while(true)
break;
} // WriteLock
} // AtomicComposition
} // while (true)
var changedArgs = new ComposablePartCatalogChangeEventArgs(addedDefinitions, removedDefinitions, null);
this.OnChanged(changedArgs);
}
