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// Copyright 2022 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#ifndef COMPONENTS_REPORTING_UTIL_DISCONNECTABLE_CLIENT_H_
#define COMPONENTS_REPORTING_UTIL_DISCONNECTABLE_CLIENT_H_
#include <memory>
#include <queue>
#include "base/containers/fixed_flat_map.h"
#include "base/feature_list.h"
#include "base/functional/callback.h"
#include "base/memory/scoped_refptr.h"
#include "base/memory/weak_ptr.h"
#include "base/sequence_checker.h"
#include "base/task/sequenced_task_runner.h"
#include "base/thread_annotations.h"
#include "components/reporting/util/status.h"
namespace reporting {
namespace disconnectable_client {
constexpr char kErrorServiceUnavailable[] = "Service is unavailable";
}
// Client connection class that handles possible disconnections.
// When the service is not available, calls are immediately responded with
// failure, including those started beforewhen the connection was available.
class DisconnectableClient {
public:
// Interface to actual connection call.
class Delegate {
public:
virtual ~Delegate() = default;
// Makes actual call to the service.
virtual void DoCall(base::OnceClosure cb) = 0;
// Processes response received from the service (OK is successful).
virtual void Respond(Status status) = 0;
};
explicit DisconnectableClient(
scoped_refptr<base::SequencedTaskRunner> task_runner);
DisconnectableClient(const DisconnectableClient& other) = delete;
DisconnectableClient& operator=(const DisconnectableClient& other) = delete;
~DisconnectableClient();
// Access to the feature controlling job limit (intended mostly for tests).
static const base::Feature& ReportingDelegateJobsLimitFeature();
static const char* MaxDelegatesRunningParamName();
// Makes a call or delays it, if there are too many ongoing calls already.
// Must be executed on task_runner_.
void MaybeMakeCall(std::unique_ptr<Delegate> delegate);
// Sets availability flag of the service.
void SetAvailability(bool is_available);
// Returns sequenced task runner for all operations.
scoped_refptr<base::SequencedTaskRunner> task_runner() const;
private:
void CallResponded(uint64_t id);
void MakeCall(std::unique_ptr<Delegate> delegate);
// Sequenced task runner - must be first member of the class.
const scoped_refptr<base::SequencedTaskRunner> task_runner_;
SEQUENCE_CHECKER(sequence_checker_);
// Availability flag.
bool is_available_ GUARDED_BY_CONTEXT(sequence_checker_){false};
// Delayed delegates queue.
std::queue<std::unique_ptr<Delegate>> delayed_delegates_
GUARDED_BY_CONTEXT(sequence_checker_);
// Map of delegates indexed by unique ids (all delegates will fail with error
// Status if service disconnects). last_id_ is used for generation of these
// unique ids.
base::flat_map<uint64_t, std::unique_ptr<Delegate>> outstanding_delegates_
GUARDED_BY_CONTEXT(sequence_checker_);
uint64_t last_id_ GUARDED_BY_CONTEXT(sequence_checker_) = 0;
// Weak pointer factory - must be last member of the class.
base::WeakPtrFactory<DisconnectableClient> weak_ptr_factory_{this};
};
} // namespace reporting
#endif // COMPONENTS_REPORTING_UTIL_DISCONNECTABLE_CLIENT_H_
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