using System; using System.Collections; using System.Collections.Generic; using System.Collections.ObjectModel; using System.Text; using System.Reflection; using System.Linq; using System.Diagnostics; namespace System.Data.Linq { using System.Data.Linq.Mapping; using System.Data.Linq.Provider; using System.Diagnostics.CodeAnalysis; public sealed class ChangeConflictCollection : ICollection<ObjectChangeConflict>, ICollection, IEnumerable<ObjectChangeConflict>, IEnumerable { private List<ObjectChangeConflict> conflicts; internal ChangeConflictCollection() { this.conflicts = new List<ObjectChangeConflict>(); } /// <summary> /// The number of conflicts in the collection /// </summary> public int Count { get { return this.conflicts.Count; } } public ObjectChangeConflict this[int index] { get { return this.conflicts[index]; } } bool ICollection<ObjectChangeConflict>.IsReadOnly { get { return true; } } void ICollection<ObjectChangeConflict>.Add(ObjectChangeConflict item) { throw Error.CannotAddChangeConflicts(); } /// <summary> /// Removes the specified conflict from the collection. /// </summary> /// <param name="item">The conflict to remove</param> /// <returns></returns> public bool Remove(ObjectChangeConflict item) { return this.conflicts.Remove(item); } /// <summary> /// Removes all conflicts from the collection /// </summary> public void Clear() { this.conflicts.Clear(); } /// <summary> /// Returns true if the specified conflict is a member of the collection. /// </summary> /// <param name="item"></param> /// <returns></returns> public bool Contains(ObjectChangeConflict item) { return this.conflicts.Contains(item); } public void CopyTo(ObjectChangeConflict[] array, int arrayIndex) { this.conflicts.CopyTo(array, arrayIndex); } /// <summary> /// Returns the enumerator for the collection. /// </summary> /// <returns></returns> public IEnumerator<ObjectChangeConflict> GetEnumerator() { return this.conflicts.GetEnumerator(); } IEnumerator IEnumerable.GetEnumerator() { return this.conflicts.GetEnumerator(); } bool ICollection.IsSynchronized { get { return false; } } object ICollection.SyncRoot { get { return null; } } void ICollection.CopyTo(Array array, int index) { ((ICollection)this.conflicts).CopyTo(array, index); } /// <summary> /// Resolves all conflicts in the collection using the specified strategy. /// </summary> /// <param name="mode">The strategy to use to resolve the conflicts.</param> public void ResolveAll(RefreshMode mode) { this.ResolveAll(mode, true); } /// <summary> /// Resolves all conflicts in the collection using the specified strategy. /// </summary> /// <param name="mode">The strategy to use to resolve the conflicts.</param> /// <param name="autoResolveDeletes">If true conflicts resulting from the modified /// object no longer existing in the database will be automatically resolved.</param> public void ResolveAll(RefreshMode mode, bool autoResolveDeletes) { foreach (ObjectChangeConflict c in this.conflicts) { if (!c.IsResolved) { c.Resolve(mode, autoResolveDeletes); } } } internal void Fill(List<ObjectChangeConflict> conflictList) { this.conflicts = conflictList; } } internal sealed class ChangeConflictSession { private DataContext context; private DataContext refreshContext; internal ChangeConflictSession(DataContext context) { this.context = context; } internal DataContext Context { get { return this.context; } } internal DataContext RefreshContext { get { if (this.refreshContext == null) { this.refreshContext = this.context.CreateRefreshContext(); } return this.refreshContext; } } } /// <summary> /// Represents an update with one or more optimistic concurrency conflicts. /// </summary> public sealed class ObjectChangeConflict { private ChangeConflictSession session; private TrackedObject trackedObject; private bool isResolved; private ReadOnlyCollection<MemberChangeConflict> memberConflicts; private object database; private object original; private bool? isDeleted; /// <summary> /// Constructor. /// </summary> /// <param name="session">The session in which the conflicts occurred.</param> /// <param name="trackedObject">The tracked item in conflict.</param> internal ObjectChangeConflict(ChangeConflictSession session, TrackedObject trackedObject) { this.session = session; this.trackedObject = trackedObject; this.original = trackedObject.CreateDataCopy(trackedObject.Original); } /// <summary> /// Constructor. /// </summary> /// <param name="session">The session in which the conflicts occurred.</param> /// <param name="trackedObject">The tracked item in conflict.</param> /// <param name="isDeleted">True if the item in conflict no longer exists in the database.</param> internal ObjectChangeConflict(ChangeConflictSession session, TrackedObject trackedObject, bool isDeleted) : this(session, trackedObject) { this.isDeleted = isDeleted; } internal ChangeConflictSession Session { get { return this.session; } } internal TrackedObject TrackedObject { get { return this.trackedObject; } } /// <summary> /// The object in conflict. /// </summary> public object Object { get { return this.trackedObject.Current; } } /// <summary> /// An instance containing the baseline original values used to perform the concurrency check. /// </summary> internal object Original { get { return this.original; } } /// <summary> /// True if the conflicts for this object have already been resovled. /// </summary> public bool IsResolved { get { return this.isResolved; } } /// <summary> /// True if the object in conflict has been deleted from the database. /// </summary> public bool IsDeleted { get { if (this.isDeleted.HasValue) { return this.isDeleted.Value; } return (this.Database == null); } } /// <summary> /// An instance containing the most recent values from the database /// </summary> internal object Database { get { if (this.database == null) { // use the 'refresh' context to retrieve the current database state DataContext ctxt = this.session.RefreshContext; object[] keyValues = CommonDataServices.GetKeyValues(this.trackedObject.Type, this.original); this.database = ctxt.Services.GetObjectByKey(this.trackedObject.Type, keyValues); } return this.database; } } /// <summary> /// Resolve member conflicts keeping current values and resetting the baseline 'Original' values /// to match the more recent 'Database' values. /// </summary> public void Resolve() { this.Resolve(RefreshMode.KeepCurrentValues, true); } /// <summary> /// Resolve member conflicts using the mode specified and resetting the baseline 'Original' values /// to match the more recent 'Database' values. /// </summary> /// <param name="refreshMode">The mode that determines how the current values are /// changed in order to resolve the conflict</param> public void Resolve(RefreshMode refreshMode) { this.Resolve(refreshMode, false); } /// <summary> /// Resolve member conflicts using the mode specified and resetting the baseline 'Original' values /// to match the more recent 'Database' values. /// </summary> /// <param name="refreshMode">The mode that determines how the current values are /// changed in order to resolve the conflict</param> /// <param name="autoResolveDeletes">If true conflicts resulting from the modified /// object no longer existing in the database will be automatically resolved.</param> public void Resolve(RefreshMode refreshMode, bool autoResolveDeletes) { if (autoResolveDeletes && this.IsDeleted) { this.ResolveDelete(); } else { // We make these calls explicity rather than simply calling // DataContext.Refresh (which does virtually the same thing) // since we want to cache the database value read. if (this.Database == null) { throw Error.RefreshOfDeletedObject(); } trackedObject.Refresh(refreshMode, this.Database); this.isResolved = true; } } /// <summary> /// Resolve a conflict where we have updated an entity that no longer exists /// in the database. /// </summary> private void ResolveDelete() { Debug.Assert(this.IsDeleted); // If the user is attempting to update an entity that no longer exists // in the database, we first need to sync the delete into the local cache. if (!trackedObject.IsDeleted) { trackedObject.ConvertToDeleted(); } // As the object have been deleted, it needs to leave the cache this.Session.Context.Services.RemoveCachedObjectLike(trackedObject.Type, trackedObject.Original); // Now that our cache is in sync, we accept the changes this.trackedObject.AcceptChanges(); this.isResolved = true; } /// <summary> /// Returns a collection of all member conflicts that caused the update to fail. /// </summary> public ReadOnlyCollection<MemberChangeConflict> MemberConflicts { get { if (this.memberConflicts == null) { var list = new List<MemberChangeConflict>(); if (this.Database != null) { // determine which members are in conflict foreach (MetaDataMember metaMember in trackedObject.Type.PersistentDataMembers) { if (!metaMember.IsAssociation && this.HasMemberConflict(metaMember)) { list.Add(new MemberChangeConflict(this, metaMember)); } } } this.memberConflicts = list.AsReadOnly(); } return this.memberConflicts; } } private bool HasMemberConflict(MetaDataMember member) { object oValue = member.StorageAccessor.GetBoxedValue(this.original); if (!member.DeclaringType.Type.IsAssignableFrom(this.database.GetType())) { return false; } object dValue = member.StorageAccessor.GetBoxedValue(this.database); return !this.AreEqual(member, oValue, dValue); } private bool AreEqual(MetaDataMember member, object v1, object v2) { if (v1 == null && v2 == null) return true; if (v1 == null || v2 == null) return false; if (member.Type == typeof(char[])) { return this.AreEqual((char[])v1, (char[])v2); } else if (member.Type == typeof(byte[])) { return this.AreEqual((byte[])v1, (byte[])v2); } else { return object.Equals(v1, v2); } } [SuppressMessage("Microsoft.Performance", "CA1822:MarkMembersAsStatic", Justification="Unknown reason.")] private bool AreEqual(char[] a1, char[] a2) { if (a1.Length != a2.Length) return false; for (int i = 0, n = a1.Length; i < n; i++) { if (a1[i] != a2[i]) return false; } return true; } [SuppressMessage("Microsoft.Performance", "CA1822:MarkMembersAsStatic", Justification="Unknown reason.")] private bool AreEqual(byte[] a1, byte[] a2) { if (a1.Length != a2.Length) return false; for (int i = 0, n = a1.Length; i < n; i++) { if (a1[i] != a2[i]) return false; } return true; } internal void OnMemberResolved() { if (!this.IsResolved) { int nResolved = this.memberConflicts.AsEnumerable().Count(m => m.IsResolved); if (nResolved == this.memberConflicts.Count) { this.Resolve(RefreshMode.KeepCurrentValues, false); } } } } /// <summary> /// Represents a single optimistic concurrency member conflict. /// </summary> public sealed class MemberChangeConflict { private ObjectChangeConflict conflict; private MetaDataMember metaMember; private object originalValue; private object databaseValue; private object currentValue; bool isResolved; internal MemberChangeConflict(ObjectChangeConflict conflict, MetaDataMember metaMember) { this.conflict = conflict; this.metaMember = metaMember; this.originalValue = metaMember.StorageAccessor.GetBoxedValue(conflict.Original); this.databaseValue = metaMember.StorageAccessor.GetBoxedValue(conflict.Database); this.currentValue = metaMember.StorageAccessor.GetBoxedValue(conflict.TrackedObject.Current); } /// <summary> /// The previous client value. /// </summary> public object OriginalValue { get { return this.originalValue; } } /// <summary> /// The current database value. /// </summary> public object DatabaseValue { get { return this.databaseValue; } } /// <summary> /// The current client value. /// </summary> public object CurrentValue { get { return this.currentValue; } } /// <summary> /// MemberInfo for the member in conflict. /// </summary> public MemberInfo Member { get { return this.metaMember.Member; } } /// <summary> /// Updates the current value to the specified value. /// </summary> public void Resolve(object value) { this.conflict.TrackedObject.RefreshMember(this.metaMember, RefreshMode.OverwriteCurrentValues, value); this.isResolved = true; this.conflict.OnMemberResolved(); } /// <summary> /// Updates the current value using the specified strategy. /// </summary> public void Resolve(RefreshMode refreshMode) { this.conflict.TrackedObject.RefreshMember(this.metaMember, refreshMode, this.databaseValue); this.isResolved = true; this.conflict.OnMemberResolved(); } /// <summary> /// True if the value was modified by the client. /// </summary> public bool IsModified { get { return this.conflict.TrackedObject.HasChangedValue(this.metaMember); } } /// <summary> /// True if the member conflict has been resolved. /// </summary> public bool IsResolved { get { return this.isResolved; } } } }