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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_CONTEXT_H
#define CEPH_CONTEXT_H
#include "common/dout.h"
#include <boost/function.hpp>
#include <list>
#include <set>
#include <memory>
#include "include/ceph_assert.h"
#include "common/Mutex.h"
#define mydout(cct, v) lgeneric_subdout(cct, context, v)
/*
* GenContext - abstract callback class
*/
template <typename T>
class GenContext {
GenContext(const GenContext& other);
const GenContext& operator=(const GenContext& other);
protected:
virtual void finish(T t) = 0;
public:
GenContext() {}
virtual ~GenContext() {} // we want a virtual destructor!!!
template <typename C>
void complete(C &&t) {
finish(std::forward<C>(t));
delete this;
}
};
template <typename T>
using GenContextURef = std::unique_ptr<GenContext<T> >;
/*
* Context - abstract callback class
*/
class Finisher;
class Context {
Context(const Context& other);
const Context& operator=(const Context& other);
protected:
virtual void finish(int r) = 0;
// variant of finish that is safe to call "synchronously." override should
// return true.
virtual bool sync_finish(int r) {
return false;
}
public:
Context() {}
virtual ~Context() {} // we want a virtual destructor!!!
virtual void complete(int r) {
finish(r);
delete this;
}
virtual bool sync_complete(int r) {
if (sync_finish(r)) {
delete this;
return true;
}
return false;
}
};
/**
* Simple context holding a single object
*/
template<class T>
class ContainerContext : public Context {
T obj;
public:
ContainerContext(T &obj) : obj(obj) {}
void finish(int r) override {}
};
template <typename T>
ContainerContext<T> *make_container_context(T &&t) {
return new ContainerContext<T>(std::forward<T>(t));
}
template <class T>
struct Wrapper : public Context {
Context *to_run;
T val;
Wrapper(Context *to_run, T val) : to_run(to_run), val(val) {}
void finish(int r) override {
if (to_run)
to_run->complete(r);
}
};
struct RunOnDelete {
Context *to_run;
RunOnDelete(Context *to_run) : to_run(to_run) {}
~RunOnDelete() {
if (to_run)
to_run->complete(0);
}
};
typedef std::shared_ptr<RunOnDelete> RunOnDeleteRef;
template <typename T>
struct LambdaContext : public Context {
T t;
LambdaContext(T &&t) : t(std::forward<T>(t)) {}
void finish(int) override {
t();
}
};
template <typename T>
LambdaContext<T> *make_lambda_context(T &&t) {
return new LambdaContext<T>(std::move(t));
}
template <typename F, typename T>
struct LambdaGenContext : GenContext<T> {
F f;
LambdaGenContext(F &&f) : f(std::forward<F>(f)) {}
void finish(T t) override {
f(std::forward<T>(t));
}
};
template <typename T, typename F>
GenContextURef<T> make_gen_lambda_context(F &&f) {
return GenContextURef<T>(new LambdaGenContext<F, T>(std::move(f)));
}
/*
* finish and destroy a list of Contexts
*/
template<class C>
inline void finish_contexts(CephContext *cct, C& finished, int result = 0)
{
if (finished.empty())
return;
C ls;
ls.swap(finished); // swap out of place to avoid weird loops
if (cct)
mydout(cct,10) << ls.size() << " contexts to finish with " << result << dendl;
for (Context* c : ls) {
if (cct)
mydout(cct,10) << "---- " << c << dendl;
c->complete(result);
}
}
class C_NoopContext : public Context {
public:
void finish(int r) override { }
};
struct C_Lock : public Context {
Mutex *lock;
Context *fin;
C_Lock(Mutex *l, Context *c) : lock(l), fin(c) {}
~C_Lock() override {
delete fin;
}
void finish(int r) override {
if (fin) {
lock->Lock();
fin->complete(r);
fin = NULL;
lock->Unlock();
}
}
};
/*
* C_Contexts - set of Contexts
*
* ContextType must be an ancestor class of ContextInstanceType, or the same class.
* ContextInstanceType must be default-constructable.
*/
template <class ContextType, class ContextInstanceType, class Container = std::list<ContextType *>>
class C_ContextsBase : public ContextInstanceType {
public:
CephContext *cct;
Container contexts;
C_ContextsBase(CephContext *cct_)
: cct(cct_)
{
}
~C_ContextsBase() override {
for (auto c : contexts) {
delete c;
}
}
void add(ContextType* c) {
contexts.push_back(c);
}
void take(Container& ls) {
Container c;
c.swap(ls);
if constexpr (std::is_same_v<Container, std::list<ContextType *>>) {
contexts.splice(contexts.end(), c);
} else {
contexts.insert(contexts.end(), c.begin(), c.end());
}
}
void complete(int r) override {
// Neuter any ContextInstanceType custom complete(), because although
// I want to look like it, I don't actually want to run its code.
Context::complete(r);
}
void finish(int r) override {
finish_contexts(cct, contexts, r);
}
bool empty() { return contexts.empty(); }
template<class C>
static ContextType *list_to_context(C& cs) {
if (cs.size() == 0) {
return 0;
} else if (cs.size() == 1) {
ContextType *c = cs.front();
cs.clear();
return c;
} else {
C_ContextsBase<ContextType, ContextInstanceType> *c(new C_ContextsBase<ContextType, ContextInstanceType>(0));
c->take(cs);
return c;
}
}
};
typedef C_ContextsBase<Context, Context> C_Contexts;
/*
* C_Gather
*
* ContextType must be an ancestor class of ContextInstanceType, or the same class.
* ContextInstanceType must be default-constructable.
*
* BUG:? only reports error from last sub to have an error return
*/
template <class ContextType, class ContextInstanceType>
class C_GatherBase {
private:
CephContext *cct;
int result;
ContextType *onfinish;
#ifdef DEBUG_GATHER
std::set<ContextType*> waitfor;
#endif
int sub_created_count;
int sub_existing_count;
mutable Mutex lock;
bool activated;
void sub_finish(ContextType* sub, int r) {
lock.Lock();
#ifdef DEBUG_GATHER
ceph_assert(waitfor.count(sub));
waitfor.erase(sub);
#endif
--sub_existing_count;
mydout(cct,10) << "C_GatherBase " << this << ".sub_finish(r=" << r << ") " << sub
#ifdef DEBUG_GATHER
<< " (remaining " << waitfor << ")"
#endif
<< dendl;
if (r < 0 && result == 0)
result = r;
if ((activated == false) || (sub_existing_count != 0)) {
lock.Unlock();
return;
}
lock.Unlock();
delete_me();
}
void delete_me() {
if (onfinish) {
onfinish->complete(result);
onfinish = 0;
}
delete this;
}
class C_GatherSub : public ContextInstanceType {
C_GatherBase *gather;
public:
C_GatherSub(C_GatherBase *g) : gather(g) {}
void complete(int r) override {
// Cancel any customized complete() functionality
// from the Context subclass we're templated for,
// we only want to hit that in onfinish, not at each
// sub finish. e.g. MDSInternalContext.
Context::complete(r);
}
void finish(int r) override {
gather->sub_finish(this, r);
gather = 0;
}
~C_GatherSub() override {
if (gather)
gather->sub_finish(this, 0);
}
};
public:
C_GatherBase(CephContext *cct_, ContextType *onfinish_)
: cct(cct_), result(0), onfinish(onfinish_),
sub_created_count(0), sub_existing_count(0),
lock("C_GatherBase::lock", true, false), //disable lockdep
activated(false)
{
mydout(cct,10) << "C_GatherBase " << this << ".new" << dendl;
}
~C_GatherBase() {
mydout(cct,10) << "C_GatherBase " << this << ".delete" << dendl;
}
void set_finisher(ContextType *onfinish_) {
Mutex::Locker l(lock);
ceph_assert(!onfinish);
onfinish = onfinish_;
}
void activate() {
lock.Lock();
ceph_assert(activated == false);
activated = true;
if (sub_existing_count != 0) {
lock.Unlock();
return;
}
lock.Unlock();
delete_me();
}
ContextType *new_sub() {
Mutex::Locker l(lock);
ceph_assert(activated == false);
sub_created_count++;
sub_existing_count++;
ContextType *s = new C_GatherSub(this);
#ifdef DEBUG_GATHER
waitfor.insert(s);
#endif
mydout(cct,10) << "C_GatherBase " << this << ".new_sub is " << sub_created_count << " " << s << dendl;
return s;
}
inline int get_sub_existing_count() const {
Mutex::Locker l(lock);
return sub_existing_count;
}
inline int get_sub_created_count() const {
Mutex::Locker l(lock);
return sub_created_count;
}
};
/*
* The C_GatherBuilder remembers each C_Context created by
* C_GatherBuilder.new_sub() in a C_Gather. When a C_Context created
* by new_sub() is complete(), C_Gather forgets about it. When
* C_GatherBuilder notices that there are no C_Context left in
* C_Gather, it calls complete() on the C_Context provided as the
* second argument of the constructor (finisher).
*
* How to use C_GatherBuilder:
*
* 1. Create a C_GatherBuilder on the stack
* 2. Call gather_bld.new_sub() as many times as you want to create new subs
* It is safe to call this 0 times, or 100, or anything in between.
* 3. If you didn't supply a finisher in the C_GatherBuilder constructor,
* set one with gather_bld.set_finisher(my_finisher)
* 4. Call gather_bld.activate()
*
* Example:
*
* C_SaferCond all_done;
* C_GatherBuilder gb(g_ceph_context, all_done);
* j.submit_entry(1, first, 0, gb.new_sub()); // add a C_Context to C_Gather
* j.submit_entry(2, first, 0, gb.new_sub()); // add a C_Context to C_Gather
* gb.activate(); // consume C_Context as soon as they complete()
* all_done.wait(); // all_done is complete() after all new_sub() are complete()
*
* The finisher may be called at any point after step 4, including immediately
* from the activate() function.
* The finisher will never be called before activate().
*
* Note: Currently, subs must be manually freed by the caller (for some reason.)
*/
template <class ContextType, class GatherType>
class C_GatherBuilderBase
{
public:
C_GatherBuilderBase(CephContext *cct_)
: cct(cct_), c_gather(NULL), finisher(NULL), activated(false)
{
}
C_GatherBuilderBase(CephContext *cct_, ContextType *finisher_)
: cct(cct_), c_gather(NULL), finisher(finisher_), activated(false)
{
}
~C_GatherBuilderBase() {
if (c_gather) {
ceph_assert(activated); // Don't forget to activate your C_Gather!
}
else {
delete finisher;
}
}
ContextType *new_sub() {
if (!c_gather) {
c_gather = new GatherType(cct, finisher);
}
return c_gather->new_sub();
}
void activate() {
if (!c_gather)
return;
ceph_assert(finisher != NULL);
activated = true;
c_gather->activate();
}
void set_finisher(ContextType *finisher_) {
finisher = finisher_;
if (c_gather)
c_gather->set_finisher(finisher);
}
GatherType *get() const {
return c_gather;
}
bool has_subs() const {
return (c_gather != NULL);
}
int num_subs_created() {
ceph_assert(!activated);
if (c_gather == NULL)
return 0;
return c_gather->get_sub_created_count();
}
int num_subs_remaining() {
ceph_assert(!activated);
if (c_gather == NULL)
return 0;
return c_gather->get_sub_existing_count();
}
private:
CephContext *cct;
GatherType *c_gather;
ContextType *finisher;
bool activated;
};
typedef C_GatherBase<Context, Context> C_Gather;
typedef C_GatherBuilderBase<Context, C_Gather > C_GatherBuilder;
class FunctionContext : public Context {
public:
FunctionContext(boost::function<void(int)> &&callback)
: m_callback(std::move(callback))
{
}
void finish(int r) override {
m_callback(r);
}
private:
boost::function<void(int)> m_callback;
};
template <class ContextType>
class ContextFactory {
public:
virtual ~ContextFactory() {}
virtual ContextType *build() = 0;
};
#undef mydout
#endif
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