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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; }
}
}
}
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