/// <summary>
/// 增加 checkpoint 完成一次以后执行的动作，每次 FlushReadWriteLock.EnterWriteLock()
/// 之前的动作在本次checkpoint完成时执行，之后的动作在下一次DoCheckpoint后执行。
/// </summary>
/// <param name="act"></param>
internal void AddActionAndPulse(Action act)
{
FlushReadWriteLock.EnterReadLock();
try
{
lock (this)
{
actionPending.Add(act);
Monitor.Pulse(this);
}
}
finally
{
FlushReadWriteLock.ExitReadLock();
}
}
private void DoCheckpoint()
{
// encodeN
foreach (var db in databases)
{
db.EncodeN();
}
// snapshot
{
FlushReadWriteLock.EnterWriteLock();
try
{
actionCurrent = actionPending;
actionPending = new List <Action>();
foreach (var db in databases)
{
db.Snapshot();
}
}
finally
{
FlushReadWriteLock.ExitWriteLock();
}
}
// flush
{
readys = new ManualResetEvent[databases.Count];
int i = 0;
foreach (var v in databases)
{
v.CommitReady.Reset();
readys[i++] = v.CommitReady;
}
if (databases.Count > 1)
{
i = 0;
Task[] flushTasks = new Task[databases.Count];
// 多数据库时，必须把flush放在线程中执行，db.Flush内部需要回调this.WaitAll。
// flush 必须都能得到执行，flushThreads的数量必须足够。
foreach (var db in databases)
{
TaskCompletionSource <bool> future = new TaskCompletionSource <bool>();
flushThreads.QueueUserWorkItem(
() =>
Util.Task.Call(() =>
{
db.Flush(this);
future.SetResult(true);
},
"Zeze.Checkpoint.Flush"
));
flushTasks[i++] = future.Task;
}
Task.WaitAll(flushTasks);
}
else
{
// 只有一个Database。同步执行。
foreach (var db in databases)
{
db.Flush(this);
}
}
readys = null;
}
// cleanup
foreach (var db in databases)
{
db.Cleanup();
}
}
