/// <summary>Adds the entity to the storage.</summary>
/// <param name="entity">The entity that must be added.</param>
/// <param name="dataSourceInfo">The parameter is not used.</param>
/// <returns>The entity with the updated recordID.</returns>
protected override TEntity AddEntityCore(TEntity entity, DataSourceInfo dataSourceInfo)
{
EntityEqualityComparer <TEntity> entityComparer = new EntityEqualityComparer <TEntity>();
try {
this.temporaryStorageLock.EnterWriteLock();
if (entity.RecordId > 0)
{
/* The entity already has an ID which suggests that it came from the original datasource */
if (this.deletionCache.Contains(entity, entityComparer))
{
/* The entity has been marked for deletion, undelete it... */
this.deletionCache.Remove(entity, entityComparer);
/* ...and mark it as updated in case any of the fields have been altered. */
TEntity repositoryEntity = entity.CreateCopyOrClone();
this.updateCache.Add(repositoryEntity);
if (this.SelectCloneDataSourceItems(dataSourceInfo))
{
return(((ICloneable)repositoryEntity).Clone() as TEntity);
}
else
{
entity.CopyFrom(repositoryEntity);
return(entity);
}
}
}
/* The entity is either new or came from another data source */
/* Determine the new temporary ID for the entity */
int newRecordId = -1;
if (this.additionCache.Count > 0)
{
newRecordId = this.additionCache.Min(t => t.RecordId) - 1;
}
TEntity copyOfEntity = entity.CreateCopyOrClone();
copyOfEntity.RecordId = newRecordId;
/* Add it to the addition cache */
this.additionCache.Add(copyOfEntity);
if (this.SelectCloneDataSourceItems(dataSourceInfo))
{
return(((ICloneable)copyOfEntity).Clone() as TEntity);
}
else
{
entity.CopyFrom(copyOfEntity);
return(entity);
}
}
finally {
if (this.temporaryStorageLock.IsWriteLockHeld)
{
this.temporaryStorageLock.ExitWriteLock();
}
}
}
/// <summary>Concatenates the global caches and local cache into one complete and up-to-date cache.</summary>
/// <param name="dataSourceInfo">Any information regarding the data store that is used as data source.</param>
/// <returns>The concatenated cache-values.</returns>
private IEnumerable <TEntity> ConcatStorage(DataSourceInfo dataSourceInfo)
{
EntityEqualityComparer <TEntity> entityComparer = new EntityEqualityComparer <TEntity>();
IEnumerable <TEntity> totalCache = this.SelectMemoryStore(dataSourceInfo).Storage;
if (this.SelectCloneDataSourceItems(dataSourceInfo))
{
totalCache = totalCache.Select(t => ((ICloneable)t).Clone() as TEntity);
}
totalCache = totalCache.Concat(this.additionCache);
/*...then remove the entities that were updated from the basic cache and replace them with the updated versions... */
totalCache = totalCache.Except(this.updateCache, entityComparer).Concat(this.updateCache);
/* ...finally, remove the deleted entities */
totalCache = totalCache.Except(this.deletionCache, entityComparer);
return(totalCache.OrderBy(t => t.RecordId));
}
/// <summary>Updates a collection of entities in the repository. Depending on the status of each entity, it is updated in the addition-cache or
/// it is added to the update-cache.</summary>
/// <param name="entities">The entities that contain the updated values.</param>
/// <param name="dataSourceInfo">Information about the data source that may not have been set at an earlier stage. This parameter is not used.
/// </param>
/// <returns>The entities as they are stored in the repository.</returns>
protected override IEnumerable <TEntity> UpdateEntitiesCore(IEnumerable <TEntity> entities, DataSourceInfo dataSourceInfo)
{
if (entities.Any(e => e.RecordId == 0))
{
throw new InvalidOperationException("Cannot update an entity whose identifier is zero.");
}
EntityEqualityComparer <TEntity> entityComparer = new EntityEqualityComparer <TEntity>();
MemoryStore <TEntity> memoryStore = this.SelectMemoryStore(dataSourceInfo);
IEnumerable <TEntity> addedEntities = entities.Where(e => e.RecordId < 0);
IEnumerable <TEntity> updatedEntities = entities.Where(e => e.RecordId > 0);
this.temporaryStorageLock.EnterWriteLock();
memoryStore.EnterReadLock();
/* Make a copy of the caches. That way, if any thing goes wrong all the changes can be made undone */
List <TEntity> tempAdditionCache = this.additionCache.ToList();
List <TEntity> tempUpdateCache = this.updateCache.ToList();
List <TEntity> tempDeletionCache = this.deletionCache.ToList();
List <TEntity> newlyAddedEntities = new List <TEntity>();
List <TEntity> currentUpdatedEntities = new List <TEntity>();
try {
foreach (TEntity addedEntity in addedEntities)
{
/* If the entity is marked for addition, update the entity in the addition cache */
if (tempAdditionCache.Contains(addedEntity, entityComparer))
{
int indexOfEntity = tempAdditionCache.IndexOf(addedEntity, entityComparer);
TEntity repositoryEntity = tempAdditionCache[indexOfEntity];
/* Copy the values of the updated entity into the cached entity */
repositoryEntity.CopyFrom(addedEntity);
newlyAddedEntities.Add(repositoryEntity);
}
else
{
throw new InvalidOperationException("Could not find the entity in the addition-cache.");
}
}
foreach (TEntity updatedEntity in updatedEntities)
{
if (memoryStore.Storage.Contains(updatedEntity, entityComparer))
{
/* If the entity is already marked for deletion, it can no longer be updated. */
if (tempDeletionCache.Contains(updatedEntity, entityComparer))
{
throw new InvalidOperationException("Cannot update the entity since it already marked for deletion.");
}
TEntity repositoryEntity;
if (tempUpdateCache.Contains(updatedEntity, entityComparer))
{
/* If the entity was already marked for update, replace it in the update cache */
int indexOfEntity = tempUpdateCache.IndexOf(updatedEntity, entityComparer);
repositoryEntity = tempUpdateCache[indexOfEntity];
/* Copy the values of the updated entity into the cached entity */
repositoryEntity.CopyFrom(updatedEntity);
}
else
{
/* Retrieve the original version of the entity from the storage */
TEntity originalEntity = memoryStore.Storage[memoryStore.Storage.IndexOf(updatedEntity, entityComparer)];
/* Create a copy of the original entity to avoid any unwanted updates of the original entity */
repositoryEntity = originalEntity.CreateCopyOrClone();
/* Copy the values of the updated entity into the (copy of) original entity */
repositoryEntity.CopyFrom(updatedEntity);
/* Store the updated entity in the update cache */
tempUpdateCache.Add(repositoryEntity);
}
currentUpdatedEntities.Add(repositoryEntity);
}
else
{
throw new InvalidOperationException("Could not find the entity in the internal cache.");
}
}
/* Replace the original caches to complete the 'transaction' */
this.additionCache = tempAdditionCache;
this.updateCache = tempUpdateCache;
this.deletionCache = tempDeletionCache;
if (this.SelectCloneDataSourceItems(dataSourceInfo))
{
return(newlyAddedEntities.Concat(currentUpdatedEntities).Select(entity => ((ICloneable)entity).Clone() as TEntity).ToList());
}
else
{
IEnumerable <TEntity> resultList = newlyAddedEntities.Concat(currentUpdatedEntities);
resultList.ForEach(entity => entities.Single(e => e.RecordId == entity.RecordId).CopyFrom(entity));
return(entities);
}
}
finally {
memoryStore.ExitReadLock();
if (this.temporaryStorageLock.IsWriteLockHeld)
{
this.temporaryStorageLock.ExitWriteLock();
}
}
}
/// <summary>Updates an entity in the storage.</summary>
/// <param name="entity">The entity that must be updated.</param>
/// <param name="dataSourceInfo">The parameter is not used.</param>
/// <returns>The updated entity.</returns>
protected override TEntity UpdateEntityCore(TEntity entity, DataSourceInfo dataSourceInfo)
{
if (entity.RecordId == 0)
{
throw new InvalidOperationException("Cannot update an entity whose identifier is zero.");
}
EntityEqualityComparer <TEntity> entityComparer = new EntityEqualityComparer <TEntity>();
MemoryStore <TEntity> memoryStore = this.SelectMemoryStore(dataSourceInfo);
try {
/* First search the temporary storage */
this.temporaryStorageLock.EnterWriteLock();
memoryStore.EnterReadLock();
if (entity.RecordId < 0)
{
if (this.additionCache.Contains(entity, entityComparer))
{
int indexOfEntity = this.additionCache.IndexOf(entity, entityComparer);
TEntity repositoryEntity = this.additionCache[indexOfEntity];
/* Copy the values of the updated entity into the cached entity */
repositoryEntity.CopyFrom(entity);
if (this.SelectCloneDataSourceItems(dataSourceInfo))
{
return(((ICloneable)repositoryEntity).Clone() as TEntity);
}
else
{
entity.CopyFrom(repositoryEntity);
return(entity);
}
}
else
{
throw new InvalidOperationException("Could not find the entity in the addition-cache.");
}
}
else
{
if (memoryStore.Storage.Contains(entity, entityComparer))
{
if (this.deletionCache.Contains(entity, entityComparer))
{
throw new InvalidOperationException("Cannot update the entity since it already marked for deletion.");
}
TEntity repositoryEntity;
if (this.updateCache.Contains(entity, entityComparer))
{
/* Retrieve the previous updated version of the entity from the cache */
int indexOfEntity = this.updateCache.IndexOf(entity, entityComparer);
repositoryEntity = this.updateCache[indexOfEntity];
/* Copy the values of the updated entity into the cached entity */
repositoryEntity.CopyFrom(entity);
}
else
{
/* Retrieve the original version of the entity from the storage */
TEntity originalEntity = memoryStore.Storage[memoryStore.Storage.IndexOf(entity, entityComparer)];
/* Create a copy of the original entity to avoid any unwanted updates of the original entity */
repositoryEntity = originalEntity.CreateCopyOrClone();
/* Copy the values of the updated entity into the (copy of) original entity */
repositoryEntity.CopyFrom(entity);
/* Store the updated entity in the update cache */
this.updateCache.Add(repositoryEntity);
}
/* Return an instance of TEntity that reflects the changes, but is disconnected from the instance that is stored in the cache
* (to avoid unwanted updates from outside the repository) */
if (this.SelectCloneDataSourceItems(dataSourceInfo))
{
return(((ICloneable)repositoryEntity).Clone() as TEntity);
}
else
{
entity.CopyFrom(repositoryEntity);
return(entity);
}
}
else
{
throw new InvalidOperationException("Could not find the entity in the internal cache.");
}
}
}
finally {
memoryStore.ExitReadLock();
if (this.temporaryStorageLock.IsWriteLockHeld)
{
this.temporaryStorageLock.ExitWriteLock();
}
}
}
/// <summary>Removes a collection of entities from the repository. Depending on the status of each entity, it is removed from the addition-cache
/// or it is added to the deletion-cache until it is saved using the <see cref="Repository{T}.SaveChanges()"/> method.</summary>
/// <param name="entities">The entities that must be removed.</param>
/// <param name="dataSourceInfo">Information about the data source that may not have been set at an earlier stage. This parameter is not used.
/// </param>
protected override void DeleteEntitiesCore(IEnumerable <TEntity> entities, DataSourceInfo dataSourceInfo)
{
if (entities.Any(e => e.RecordId == 0))
{
throw new InvalidOperationException("Cannot delete an entity whose identifier is zero.");
}
IEqualityComparer <TEntity> entityComparer = new EntityEqualityComparer <TEntity>();
MemoryStore <TEntity> memoryStore = this.SelectMemoryStore(dataSourceInfo);
this.temporaryStorageLock.EnterWriteLock();
memoryStore.EnterReadLock();
IEnumerable <TEntity> addedEntities = entities.Where(e => e.RecordId < 0);
IEnumerable <TEntity> existingEntities = entities.Where(e => e.RecordId > 0);
/* Make a copy of the caches. That way, if any thing goes wrong all the changes can be made undone */
List <TEntity> tempAdditionCache = this.additionCache.ToList();
List <TEntity> tempUpdateCache = this.updateCache.ToList();
List <TEntity> tempDeletionCache = this.deletionCache.ToList();
try {
foreach (TEntity addedEntity in addedEntities)
{
/* If the ID is negative, it should be marked for addition */
if (tempAdditionCache.Contains(addedEntity, entityComparer))
{
tempAdditionCache.Remove(addedEntity, entityComparer);
}
else
{
throw new InvalidOperationException("Could not find the entity in the memory.");
}
}
foreach (TEntity existingEntity in existingEntities)
{
/* If the entity was marked for update, remove that mark */
if (tempUpdateCache.Contains(existingEntity, entityComparer))
{
tempUpdateCache.Remove(existingEntity, entityComparer);
}
/* If the entity exists in the original data source and has not yet been marked for deletion, mark it now */
if (memoryStore.Storage.Contains(existingEntity, entityComparer))
{
if (!tempDeletionCache.Contains(existingEntity, entityComparer))
{
tempDeletionCache.Add(existingEntity);
}
else
{
throw new InvalidOperationException("Cannot delete the same entity more then once.");
}
}
else
{
throw new InvalidOperationException("Could not find the entity in the internal cache.");
}
}
/* Replace the original caches to complete the 'transaction' */
this.additionCache = tempAdditionCache;
this.updateCache = tempUpdateCache;
this.deletionCache = tempDeletionCache;
}
finally {
memoryStore.ExitReadLock();
if (this.temporaryStorageLock.IsWriteLockHeld)
{
this.temporaryStorageLock.ExitWriteLock();
}
}
}
/// <summary>Deletes the entity from the storage.</summary>
/// <param name="entity">The entity that must be removed.</param>
/// <param name="dataSourceInfo">The parameter is not used.</param>
protected override void DeleteEntityCore(TEntity entity, DataSourceInfo dataSourceInfo)
{
if (entity.RecordId == 0)
{
throw new InvalidOperationException("Cannot delete an entity whose identifier is zero.");
}
IEqualityComparer <TEntity> entityComparer = new EntityEqualityComparer <TEntity>();
MemoryStore <TEntity> memoryStore = this.SelectMemoryStore(dataSourceInfo);
try {
/* First search the temporary storage */
this.temporaryStorageLock.EnterWriteLock();
memoryStore.EnterReadLock();
if (entity.RecordId < 0)
{
/* If the ID is negative, it should be marked for addition */
if (this.additionCache.Contains(entity, entityComparer))
{
this.additionCache.Remove(entity, entityComparer);
}
else
{
throw new InvalidOperationException("Could not find the entity in the memory.");
}
}
else
{
/* If the entity was marked for update, remove that mark */
if (this.updateCache.Contains(entity, entityComparer))
{
this.updateCache.Remove(entity, entityComparer);
}
/* If the entity exists in the original data source and has not yet been marked for deletion, mark it now */
if (memoryStore.Storage.Contains(entity, entityComparer))
{
if (!this.deletionCache.Contains(entity, entityComparer))
{
this.deletionCache.Add(entity);
}
else
{
throw new InvalidOperationException("Cannot delete the same entity more then once.");
}
}
else
{
throw new InvalidOperationException("Could not find the entity in the memory.");
}
}
}
finally {
memoryStore.ExitReadLock();
if (this.temporaryStorageLock.IsWriteLockHeld)
{
this.temporaryStorageLock.ExitWriteLock();
}
}
}
/// <summary>Adds a collection of new entities to the repository. They are added to the addition cache until it is saved using the
/// <see cref="Repository{T}.SaveChanges()"/> method. A temporary (negative) RecordID is assigned to the entities. This will be reset when the entity is
/// saved.</summary>
/// <param name="entities">The entities that must be added.</param>
/// <param name="dataSourceInfo">Information about the data source that may not have been set at an earlier stage. This parameter is not used.
/// </param>
/// <returns>The entities as they were added to the repository.</returns>
protected override IEnumerable <TEntity> AddEntitiesCore(IEnumerable <TEntity> entities, DataSourceInfo dataSourceInfo)
{
EntityEqualityComparer <TEntity> entityComparer = new EntityEqualityComparer <TEntity>();
/* Place the entities in a list to keep track of the entities that have been handled */
List <TEntity> unhandledEntities = entities.ToList();
this.temporaryStorageLock.EnterWriteLock();
/* Make a copy of the caches. That way, if any thing goes wrong all the changes can be made undone */
List <TEntity> tempDeletionCache = this.deletionCache.ToList();
List <TEntity> tempUpdateCache = this.updateCache.ToList();
List <TEntity> tempAdditionCache = this.additionCache.ToList();
List <TEntity> updatedEntities = new List <TEntity>();
List <TEntity> addedEntities = new List <TEntity>();
Dictionary <TEntity, TEntity> handledEntities = new Dictionary <TEntity, TEntity>();
try {
if (entities.Any(e => e.RecordId > 0))
{
IEnumerable <TEntity> existingEntities = entities.Where(e => e.RecordId > 0);
ReferenceEqualityComparer <TEntity> referenceComparer = new ReferenceEqualityComparer <TEntity>();
/* At least some of the entities already have an ID which suggests that they came from the original datasource */
foreach (TEntity existingEntity in existingEntities)
{
if (tempDeletionCache.Contains(existingEntity, entityComparer))
{
/* The entity has been marked for deletion, undelete it... */
tempDeletionCache.Remove(existingEntity, entityComparer);
/* ...and mark it as updated in case any of the fields have been altered. */
TEntity repositoryEntity = existingEntity.CreateCopyOrClone();
tempUpdateCache.Add(repositoryEntity);
updatedEntities.Add(repositoryEntity);
handledEntities.Add(existingEntity, repositoryEntity);
bool removeResult = unhandledEntities.Remove(existingEntity, referenceComparer);
Debug.Assert(removeResult, "Somehow the result could not be removed from the collection of handled entities.");
}
}
}
if (unhandledEntities.Count > 0)
{
/* At least some of the entities are either new or came from another data source */
/* Determine the new temporary ID for the entities */
int newRecordId = -1;
if (tempAdditionCache.Count > 0)
{
newRecordId = tempAdditionCache.Min(t => t.RecordId) - 1;
}
foreach (TEntity unhandledEntity in unhandledEntities)
{
TEntity copyOfEntity = unhandledEntity.CreateCopyOrClone();
copyOfEntity.RecordId = newRecordId;
--newRecordId;
/* Add it to the addition cache */
tempAdditionCache.Add(copyOfEntity);
addedEntities.Add(copyOfEntity);
handledEntities.Add(unhandledEntity, copyOfEntity);
}
}
/* Replace the original caches to complete the 'transaction' */
this.deletionCache = tempDeletionCache;
this.updateCache = tempUpdateCache;
this.additionCache = tempAdditionCache;
if (this.SelectCloneDataSourceItems(dataSourceInfo))
{
return(addedEntities.Concat(updatedEntities).Select(entity => ((ICloneable)entity).Clone() as TEntity).ToList());
}
else
{
handledEntities.ForEach(kvp => kvp.Key.CopyFrom(kvp.Value));
return(entities);
}
}
finally {
this.temporaryStorageLock.ExitWriteLock();
}
}
