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// -*- mode:C++; tab-width:8; c-basic-offset:2; indent-tabs-mode:t -*-
// vim: ts=8 sw=2 smarttab
/*
* Ceph - scalable distributed file system
*
* Copyright (C) 2012 Red Hat
*
* This is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License version 2.1, as published by the Free Software
* Foundation. See file COPYING.
*
*/
#ifndef MDS_CONTEXT_H
#define MDS_CONTEXT_H
#include "include/Context.h"
class MDS;
/**
* Completion which has access to a reference to the global MDS instance.
*
* This class exists so that Context subclasses can provide the MDS pointer
* from a pointer they already had, e.g. MDCache or Locker, rather than
* necessarily having to carry around an extra MDS* pointer.
*/
class MDSContext : public Context
{
protected:
virtual MDS *get_mds() = 0;
};
/**
* A context which must be called with the big MDS lock held. Subclass
* this with a get_mds implementation.
*/
class MDSInternalContextBase : public MDSContext
{
public:
void complete(int r);
};
/**
* General purpose, lets you pass in an MDS pointer.
*/
class MDSInternalContext : public MDSInternalContextBase
{
protected:
MDS *mds;
virtual MDS* get_mds();
public:
MDSInternalContext(MDS *mds_) : mds(mds_) {
assert(mds != NULL);
}
};
/**
* Wrap a regular Context up as an Internal context. Useful
* if you're trying to work with one of our more generic frameworks.
*/
class MDSInternalContextWrapper : public MDSInternalContextBase
{
protected:
MDS *mds;
Context *fin;
MDS *get_mds();
public:
MDSInternalContextWrapper(MDS *m, Context *c) : mds(m), fin(c) {}
void finish(int r);
};
class MDSIOContextBase : public MDSContext
{
void complete(int r);
};
/**
* Completion for an I/O operation, takes big MDS lock
* before executing finish function.
*/
class MDSIOContext : public MDSIOContextBase
{
protected:
MDS *mds;
virtual MDS* get_mds();
public:
MDSIOContext(MDS *mds_) : mds(mds_) {
assert(mds != NULL);
}
};
/**
* Wrap a regular Context up as an IO Context. Useful
* if you're trying to work with one of our more generic frameworks.
*/
class MDSIOContextWrapper : public MDSIOContextBase
{
protected:
MDS *mds;
Context *fin;
MDS *get_mds();
public:
MDSIOContextWrapper(MDS *m, Context *c) : mds(m), fin(c) {}
void finish(int r);
};
/**
* No-op for callers expecting MDSInternalContextBase
*/
class C_MDSInternalNoop : public MDSInternalContextBase
{
virtual MDS* get_mds() {assert(0);}
public:
void finish(int r) {}
void complete(int r) {}
};
/**
* This class is used where you have an MDSInternalContextBase but
* you sometimes want to call it back from an I/O completion.
*/
class C_IO_Wrapper : public MDSIOContext
{
private:
MDSInternalContextBase *wrapped;
public:
C_IO_Wrapper(MDS *mds_, MDSInternalContextBase *wrapped_) : MDSIOContext(mds_), wrapped(wrapped_) {
assert(wrapped != NULL);
}
virtual void finish(int r) {
wrapped->complete(r);
}
};
/**
* Gather needs a default-constructable class
*/
class MDSInternalContextGather : public MDSInternalContextBase
{
protected:
MDS *get_mds();
};
class MDSGather : public C_GatherBase<MDSInternalContextBase, MDSInternalContextGather>
{
public:
MDSGather(CephContext *cct, MDSInternalContextBase *onfinish) : C_GatherBase<MDSInternalContextBase, MDSInternalContextGather>(cct, onfinish) {}
protected:
virtual MDS *get_mds() {return NULL;}
};
typedef C_GatherBuilderBase<MDSInternalContextBase, MDSGather> MDSGatherBuilder;
#endif // MDS_CONTEXT_H
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