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FLocal/Common/actions/ChangeSet.cs

117 lines
4.1 KiB

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using FLocal.Core;
using FLocal.Core.DB;
namespace FLocal.Common.actions {
/// <summary>
/// Note that you should create ChangeSet instances outside of transactions they're using!
/// Otherwise, there will be a 100% DB deadlock in Dispose (or data in registry won't update)
/// </summary>
internal class ChangeSet : IDisposable {
private static readonly object tablesLockOrder_locker = new object();
private static IEnumerable<string> tablesLockOrder {
get {
return Cache<IEnumerable<string>>.instance.get(
tablesLockOrder_locker,
() => new List<string>() {
dataobjects.Thread.TableSpec.TABLE, //thread should come first because of Board.newThread locking order with two changesets
dataobjects.Board.TableSpec.TABLE,
dataobjects.Post.TableSpec.TABLE,
dataobjects.Post.RevisionTableSpec.TABLE,
dataobjects.Account.TableSpec.TABLE,
dataobjects.User.TableSpec.TABLE,
dataobjects.AccountSettings.TableSpec.TABLE,
dataobjects.AccountIndicator.TableSpec.TABLE,
dataobjects.Thread.ReadMarkerTableSpec.TABLE,
dataobjects.Board.ReadMarkerTableSpec.TABLE,
dataobjects.Session.TableSpec.TABLE,
}
);
}
}
private object locker = new object();
private bool isAdding;
private bool isProcessing;
private bool isProcessed;
private Dictionary<string, HashSet<AbstractChange>> changesByTable;
public ChangeSet() {
this.isAdding = false;
this.isProcessing = false;
this.isProcessed = false;
this.changesByTable = new Dictionary<string,HashSet<AbstractChange>>();
foreach(string table in tablesLockOrder) {
this.changesByTable[table] = new HashSet<AbstractChange>();
}
}
public void Add(AbstractChange change) {
lock(locker) {
if(this.isAdding) throw new CriticalException("Cannot add inside add");
if(this.isProcessing || this.isProcessed) throw new CriticalException("ChangeSet is readonly");
this.isAdding = true;
}
if(!this.changesByTable.ContainsKey(change.tableSpec.name)) throw new CriticalException("Table not supported");
this.changesByTable[change.tableSpec.name].Add(change);
this.isAdding = false;
foreach(AbstractChange referencedChange in change.references) {
this.Add(referencedChange);
}
}
private void ApplyToChange(Transaction transaction, AbstractChange change) {
foreach(AbstractChange referenced in change.references) {
if(!referenced.getId().HasValue) {
this.ApplyToChange(transaction, referenced);
}
}
change.Apply(transaction);
}
public void Apply(Transaction transaction) {
lock(this.locker) {
if(this.isAdding) throw new CriticalException("Cannot process while adding");
if(this.isProcessing || this.isProcessed) throw new CriticalException("ChangeSet is already processed");
this.isProcessing = true;
}
foreach(string table in tablesLockOrder) {
foreach(AbstractChange change in (from AbstractChange _change in this.changesByTable[table] orderby _change.getId() select _change)) {
change.Lock(transaction);
}
}
foreach(KeyValuePair<string, HashSet<AbstractChange>> kvp in this.changesByTable) {
foreach(AbstractChange change in kvp.Value) {
this.ApplyToChange(transaction, change);
}
}
this.isProcessed = true;
}
public void Dispose() {
//if(!this.isProcessed) throw new CriticalException("ChangeSet is not processed yet");
if(this.isProcessed) {
foreach(KeyValuePair<string, HashSet<AbstractChange>> kvp in this.changesByTable) {
foreach(AbstractChange change in kvp.Value) {
if(change.getId().HasValue) {
try {
change.tableSpec.refreshSqlObject(change.getId().Value);
} catch(NotFoundInDBException) {
//it seems something broken earlier; transaction rollback etc...
}
} //otherwise we're disposing because of sql error or something, so we should show real cause of problem, not "id is null"
}
}
}
}
}
}