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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_SUPPORT_REF_COUNTED_H
+#define GRPC_CORE_LIB_SUPPORT_REF_COUNTED_H
+
+#include <grpc/support/log.h>
+#include <grpc/support/sync.h>
+
+#include "src/core/lib/debug/trace.h"
+#include "src/core/lib/support/debug_location.h"
+#include "src/core/lib/support/memory.h"
+
+namespace grpc_core {
+
+// A base class for reference-counted objects.
+// New objects should be created via New() and start with a refcount of 1.
+// When the refcount reaches 0, the object will be deleted via Delete().
+class RefCounted {
+ public:
+ void Ref() { gpr_ref(&refs_); }
+
+ void Unref() {
+ if (gpr_unref(&refs_)) {
+ Delete(this);
+ }
+ }
+
+ // Not copyable nor movable.
+ RefCounted(const RefCounted&) = delete;
+ RefCounted& operator=(const RefCounted&) = delete;
+
+ protected:
+ // Allow Delete() to access destructor.
+ template <typename T>
+ friend void Delete(T*);
+
+ RefCounted() { gpr_ref_init(&refs_, 1); }
+
+ virtual ~RefCounted() {}
+
+ private:
+ gpr_refcount refs_;
+};
+
+// An alternative version of the RefCounted 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.
+class RefCountedWithTracing {
+ public:
+ void Ref() { gpr_ref(&refs_); }
+
+ void Ref(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 ref %" PRIdPTR " -> %" PRIdPTR " %s",
+ trace_flag_->name(), this, location.file(), location.line(),
+ old_refs, old_refs + 1, reason);
+ }
+ Ref();
+ }
+
+ 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();
+ }
+
+ // Not copyable nor movable.
+ RefCountedWithTracing(const RefCountedWithTracing&) = delete;
+ RefCountedWithTracing& operator=(const RefCountedWithTracing&) = delete;
+
+ protected:
+ // Allow Delete() to access destructor.
+ template <typename T>
+ friend void Delete(T*);
+
+ RefCountedWithTracing() : RefCountedWithTracing(nullptr) {}
+
+ explicit RefCountedWithTracing(TraceFlag* trace_flag)
+ : trace_flag_(trace_flag) {
+ gpr_ref_init(&refs_, 1);
+ }
+
+ virtual ~RefCountedWithTracing() {}
+
+ private:
+ TraceFlag* trace_flag_ = nullptr;
+ gpr_refcount refs_;
+};
+
+} // namespace grpc_core
+
+#endif /* GRPC_CORE_LIB_SUPPORT_REF_COUNTED_H */