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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) 2004-2006 Sage Weil <sage@newdream.net>
*
* 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 CEPH_REFCOUNTEDOBJ_H
#define CEPH_REFCOUNTEDOBJ_H
#include "common/ceph_mutex.h"
#include "common/ref.h"
#include "include/common_fwd.h"
#include <atomic>
/* This class provides mechanisms to make a sub-class work with
* boost::intrusive_ptr (aka ceph::ref_t).
*
* Generally, you'll want to inherit from RefCountedObjectSafe and not from
* RefCountedObject directly. This is because the ::get and ::put methods are
* public and can be used to create/delete references outside of the
* ceph::ref_t pointers with the potential to leak memory.
*
* It is also suggested that you make constructors and destructors private in
* your final class. This prevents instantiation of the object with assignment
* to a raw pointer. Consequently, you'll want to use ceph::make_ref<> to
* create a ceph::ref_t<> holding your object:
*
* auto ptr = ceph::make_ref<Foo>(...);
*
* Use FRIEND_MAKE_REF(ClassName) to allow ceph::make_ref to call the private
* constructors.
*
*/
namespace TOPNSPC::common {
class RefCountedObject {
public:
void set_cct(CephContext *c) {
cct = c;
}
uint64_t get_nref() const {
return nref;
}
const RefCountedObject *get() const {
_get();
return this;
}
RefCountedObject *get() {
_get();
return this;
}
void put() const;
protected:
RefCountedObject() = default;
RefCountedObject(const RefCountedObject& o) : cct(o.cct) {}
RefCountedObject& operator=(const RefCountedObject& o) = delete;
RefCountedObject(RefCountedObject&&) = delete;
RefCountedObject& operator=(RefCountedObject&&) = delete;
RefCountedObject(CephContext* c) : cct(c) {}
virtual ~RefCountedObject();
private:
void _get() const;
#if defined(WITH_SEASTAR) && !defined(WITH_ALIEN)
// crimson is single threaded at the moment
mutable uint64_t nref{1};
#else
mutable std::atomic<uint64_t> nref{1};
#endif
CephContext *cct{nullptr};
};
class RefCountedObjectSafe : public RefCountedObject {
public:
RefCountedObject *get() = delete;
const RefCountedObject *get() const = delete;
void put() const = delete;
protected:
template<typename... Args>
RefCountedObjectSafe(Args&&... args) : RefCountedObject(std::forward<Args>(args)...) {}
virtual ~RefCountedObjectSafe() override {}
};
#if !defined(WITH_SEASTAR)|| defined(WITH_ALIEN)
/**
* RefCountedCond
*
* a refcounted condition, will be removed when all references are dropped
*/
struct RefCountedCond : public RefCountedObject {
RefCountedCond() = default;
~RefCountedCond() = default;
int wait() {
std::unique_lock l(lock);
while (!complete) {
cond.wait(l);
}
return rval;
}
void done(int r) {
std::lock_guard l(lock);
rval = r;
complete = true;
cond.notify_all();
}
void done() {
done(0);
}
private:
bool complete = false;
ceph::mutex lock = ceph::make_mutex("RefCountedCond::lock");
ceph::condition_variable cond;
int rval = 0;
};
/**
* RefCountedWaitObject
*
* refcounted object that allows waiting for the object's last reference.
* Any referrer can either put or put_wait(). A simple put() will return
* immediately, a put_wait() will return only when the object is destroyed.
* e.g., useful when we want to wait for a specific event completion. We
* use RefCountedCond, as the condition can be referenced after the object
* destruction.
*
*/
struct RefCountedWaitObject {
std::atomic<uint64_t> nref = { 1 };
RefCountedCond *c;
RefCountedWaitObject() {
c = new RefCountedCond;
}
virtual ~RefCountedWaitObject() {
c->put();
}
RefCountedWaitObject *get() {
nref++;
return this;
}
bool put() {
bool ret = false;
RefCountedCond *cond = c;
cond->get();
if (--nref == 0) {
cond->done();
delete this;
ret = true;
}
cond->put();
return ret;
}
void put_wait() {
RefCountedCond *cond = c;
cond->get();
if (--nref == 0) {
cond->done();
delete this;
} else {
cond->wait();
}
cond->put();
}
};
#endif // !defined(WITH_SEASTAR)|| defined(WITH_ALIEN)
static inline void intrusive_ptr_add_ref(const RefCountedObject *p) {
p->get();
}
static inline void intrusive_ptr_release(const RefCountedObject *p) {
p->put();
}
}
using RefCountedPtr = ceph::ref_t<TOPNSPC::common::RefCountedObject>;
#endif
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