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/*
*
* Copyright 2015 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_TRANSPORT_CONNECTIVITY_STATE_H
#define GRPC_CORE_LIB_TRANSPORT_CONNECTIVITY_STATE_H
#include <grpc/support/port_platform.h>
#include <map>
#include <memory>
#include "absl/status/status.h"
#include <grpc/grpc.h>
#include "src/core/lib/debug/trace.h"
#include "src/core/lib/gprpp/atomic.h"
#include "src/core/lib/gprpp/orphanable.h"
#include "src/core/lib/iomgr/closure.h"
#include "src/core/lib/iomgr/exec_ctx.h"
#include "src/core/lib/iomgr/work_serializer.h"
namespace grpc_core {
extern TraceFlag grpc_connectivity_state_trace;
// Enum to string conversion.
const char* ConnectivityStateName(grpc_connectivity_state state);
// Interface for watching connectivity state.
// Subclasses must implement the Notify() method.
//
// Note: Most callers will want to use
// AsyncConnectivityStateWatcherInterface instead.
class ConnectivityStateWatcherInterface
: public InternallyRefCounted<ConnectivityStateWatcherInterface> {
public:
~ConnectivityStateWatcherInterface() override = default;
// Notifies the watcher that the state has changed to new_state.
virtual void Notify(grpc_connectivity_state new_state,
const absl::Status& status) = 0;
void Orphan() override { Unref(); }
};
// An alternative watcher interface that performs notifications via an
// asynchronous callback scheduled on the ExecCtx.
// Subclasses must implement the OnConnectivityStateChange() method.
class AsyncConnectivityStateWatcherInterface
: public ConnectivityStateWatcherInterface {
public:
~AsyncConnectivityStateWatcherInterface() override = default;
// Schedules a closure on the ExecCtx to invoke
// OnConnectivityStateChange() asynchronously.
void Notify(grpc_connectivity_state new_state,
const absl::Status& status) final;
protected:
class Notifier;
// If \a work_serializer is nullptr, then the notification will be scheduled
// on the ExecCtx.
explicit AsyncConnectivityStateWatcherInterface(
std::shared_ptr<WorkSerializer> work_serializer = nullptr)
: work_serializer_(std::move(work_serializer)) {}
// Invoked asynchronously when Notify() is called.
virtual void OnConnectivityStateChange(grpc_connectivity_state new_state,
const absl::Status& status) = 0;
private:
std::shared_ptr<WorkSerializer> work_serializer_;
};
// Tracks connectivity state. Maintains a list of watchers that are
// notified whenever the state changes.
//
// Note that once the state becomes SHUTDOWN, watchers will be notified
// and then automatically orphaned (i.e., RemoveWatcher() does not need
// to be called).
class ConnectivityStateTracker {
public:
explicit ConnectivityStateTracker(
const char* name, grpc_connectivity_state state = GRPC_CHANNEL_IDLE,
const absl::Status& status = absl::Status())
: name_(name), state_(state), status_(status) {}
~ConnectivityStateTracker();
// Adds a watcher.
// If the current state is different than initial_state, the watcher
// will be notified immediately. Otherwise, it will be notified
// whenever the state changes.
// Not thread safe; access must be serialized with an external lock.
void AddWatcher(grpc_connectivity_state initial_state,
OrphanablePtr<ConnectivityStateWatcherInterface> watcher);
// Removes a watcher. The watcher will be orphaned.
// Not thread safe; access must be serialized with an external lock.
void RemoveWatcher(ConnectivityStateWatcherInterface* watcher);
// Sets connectivity state.
// Not thread safe; access must be serialized with an external lock.
void SetState(grpc_connectivity_state state, const absl::Status& status,
const char* reason);
// Gets the current state.
// Thread safe; no need to use an external lock.
grpc_connectivity_state state() const;
// Get the current status.
// Not thread safe; access must be serialized with an external lock.
absl::Status status() const { return status_; }
private:
const char* name_;
Atomic<grpc_connectivity_state> state_;
absl::Status status_;
// TODO(roth): Once we can use C++-14 heterogeneous lookups, this can
// be a set instead of a map.
std::map<ConnectivityStateWatcherInterface*,
OrphanablePtr<ConnectivityStateWatcherInterface>>
watchers_;
};
} // namespace grpc_core
#endif /* GRPC_CORE_LIB_TRANSPORT_CONNECTIVITY_STATE_H */
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