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/*
*
* Copyright 2017 gRPC authors.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*
*/
#ifndef GRPC_CORE_LIB_GPRPP_ORPHANABLE_H
#define GRPC_CORE_LIB_GPRPP_ORPHANABLE_H
#include <grpc/support/port_platform.h>
#include <grpc/support/log.h>
#include <grpc/support/sync.h>
#include <cinttypes>
#include <memory>
#include "src/core/lib/debug/trace.h"
#include "src/core/lib/gprpp/abstract.h"
#include "src/core/lib/gprpp/debug_location.h"
#include "src/core/lib/gprpp/memory.h"
#include "src/core/lib/gprpp/ref_counted_ptr.h"
namespace grpc_core {
// A base class for orphanable objects, which have one external owner
// but are not necessarily destroyed immediately when the external owner
// gives up ownership. Instead, the owner calls the object's Orphan()
// method, and the object then takes responsibility for its own cleanup
// and destruction.
class Orphanable {
public:
// Gives up ownership of the object. The implementation must arrange
// to eventually destroy the object without further interaction from the
// caller.
virtual void Orphan() GRPC_ABSTRACT;
// Not copyable or movable.
Orphanable(const Orphanable&) = delete;
Orphanable& operator=(const Orphanable&) = delete;
GRPC_ABSTRACT_BASE_CLASS
protected:
Orphanable() {}
virtual ~Orphanable() {}
};
template <typename T>
class OrphanableDelete {
public:
void operator()(T* p) { p->Orphan(); }
};
template <typename T, typename Deleter = OrphanableDelete<T>>
using OrphanablePtr = std::unique_ptr<T, Deleter>;
template <typename T, typename... Args>
inline OrphanablePtr<T> MakeOrphanable(Args&&... args) {
return OrphanablePtr<T>(New<T>(std::forward<Args>(args)...));
}
// A type of Orphanable with internal ref-counting.
template <typename Child>
class InternallyRefCounted : public Orphanable {
public:
// Not copyable nor movable.
InternallyRefCounted(const InternallyRefCounted&) = delete;
InternallyRefCounted& operator=(const InternallyRefCounted&) = delete;
GRPC_ABSTRACT_BASE_CLASS
protected:
// Allow Delete() to access destructor.
template <typename T>
friend void Delete(T*);
// Allow RefCountedPtr<> to access Unref() and IncrementRefCount().
friend class RefCountedPtr<Child>;
InternallyRefCounted() { gpr_ref_init(&refs_, 1); }
virtual ~InternallyRefCounted() {}
RefCountedPtr<Child> Ref() GRPC_MUST_USE_RESULT {
IncrementRefCount();
return RefCountedPtr<Child>(static_cast<Child*>(this));
}
void Unref() {
if (gpr_unref(&refs_)) {
Delete(this);
}
}
private:
void IncrementRefCount() { gpr_ref(&refs_); }
gpr_refcount refs_;
};
// An alternative version of the InternallyRefCounted base class that
// supports tracing. This is intended to be used in cases where the
// object will be handled both by idiomatic C++ code using smart
// pointers and legacy code that is manually calling Ref() and Unref().
// Once all of our code is converted to idiomatic C++, we may be able to
// eliminate this class.
template <typename Child>
class InternallyRefCountedWithTracing : public Orphanable {
public:
// Not copyable nor movable.
InternallyRefCountedWithTracing(const InternallyRefCountedWithTracing&) =
delete;
InternallyRefCountedWithTracing& operator=(
const InternallyRefCountedWithTracing&) = delete;
GRPC_ABSTRACT_BASE_CLASS
protected:
// Allow Delete() to access destructor.
template <typename T>
friend void Delete(T*);
// Allow RefCountedPtr<> to access Unref() and IncrementRefCount().
friend class RefCountedPtr<Child>;
InternallyRefCountedWithTracing()
: InternallyRefCountedWithTracing(static_cast<TraceFlag*>(nullptr)) {}
explicit InternallyRefCountedWithTracing(TraceFlag* trace_flag)
: trace_flag_(trace_flag) {
gpr_ref_init(&refs_, 1);
}
#ifdef NDEBUG
explicit InternallyRefCountedWithTracing(DebugOnlyTraceFlag* trace_flag)
: InternallyRefCountedWithTracing() {}
#endif
virtual ~InternallyRefCountedWithTracing() {}
RefCountedPtr<Child> Ref() GRPC_MUST_USE_RESULT {
IncrementRefCount();
return RefCountedPtr<Child>(static_cast<Child*>(this));
}
RefCountedPtr<Child> Ref(const DebugLocation& location,
const char* reason) GRPC_MUST_USE_RESULT {
if (location.Log() && trace_flag_ != nullptr && trace_flag_->enabled()) {
gpr_atm old_refs = gpr_atm_no_barrier_load(&refs_.count);
gpr_log(GPR_DEBUG, "%s:%p %s:%d ref %" PRIdPTR " -> %" PRIdPTR " %s",
trace_flag_->name(), this, location.file(), location.line(),
old_refs, old_refs + 1, reason);
}
return Ref();
}
// TODO(roth): Once all of our code is converted to C++ and can use
// RefCountedPtr<> instead of manual ref-counting, make the Unref() methods
// private, since they will only be used by RefCountedPtr<>, which is a
// friend of this class.
void Unref() {
if (gpr_unref(&refs_)) {
Delete(this);
}
}
void Unref(const DebugLocation& location, const char* reason) {
if (location.Log() && trace_flag_ != nullptr && trace_flag_->enabled()) {
gpr_atm old_refs = gpr_atm_no_barrier_load(&refs_.count);
gpr_log(GPR_DEBUG, "%s:%p %s:%d unref %" PRIdPTR " -> %" PRIdPTR " %s",
trace_flag_->name(), this, location.file(), location.line(),
old_refs, old_refs - 1, reason);
}
Unref();
}
private:
void IncrementRefCount() { gpr_ref(&refs_); }
TraceFlag* trace_flag_ = nullptr;
gpr_refcount refs_;
};
} // namespace grpc_core
#endif /* GRPC_CORE_LIB_GPRPP_ORPHANABLE_H */
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