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// Copyright 2023 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_UNIFIED_CONSENT_CONSENT_THROTTLE_H_
#define COMPONENTS_UNIFIED_CONSENT_CONSENT_THROTTLE_H_
#include <vector>
#include "base/functional/callback.h"
#include "base/scoped_observation.h"
#include "base/time/time.h"
#include "base/timer/timer.h"
#include "components/unified_consent/url_keyed_data_collection_consent_helper.h"
namespace unified_consent {
// This class throttles consent requests when the underlying consent helper is
// still initializing. It operates in two modes:
//
// 1) If the underlying consent helper is still initializing:
// - It holds requests in a queue for up to as long as the timeout.
// - If the consent helper finishes initializing in that time, it will call
// the request callback with the definitive answer.
// - If the consent helper doesn't finish initializing in that time, it
// will call the callback with a False answer.
//
// 2) If the underlying consent helper is already initialized, this class is
// just a passthrough, and the underlying consent helper and request
// callback are both called synchronously.
class ConsentThrottle : public UrlKeyedDataCollectionConsentHelper::Observer {
public:
using RequestCallback = base::OnceCallback<void(bool)>;
explicit ConsentThrottle(
std::unique_ptr<UrlKeyedDataCollectionConsentHelper> consent_helper,
base::TimeDelta timeout = base::Seconds(5));
ConsentThrottle(const ConsentThrottle&) = delete;
ConsentThrottle& operator=(const ConsentThrottle&) = delete;
virtual ~ConsentThrottle();
// UrlKeyedDataCollectionConsentHelper::Observer:
void OnUrlKeyedDataCollectionConsentStateChanged(
UrlKeyedDataCollectionConsentHelper* consent_helper) override;
// If the underlying consent helper is initialized already, this method calls
// `callback` synchronously with the result. If not, it will hold the request
// up until the timeout for the consent helper to initialize.
void EnqueueRequest(RequestCallback callback);
private:
// This is run periodically to sweep away old queued requests.
void OnTimeoutExpired();
// The underlying consent helper.
std::unique_ptr<UrlKeyedDataCollectionConsentHelper> consent_helper_;
// The minimum timeout duration to hold the request for.
base::TimeDelta timeout_;
// Observe the consent helper to handle to state changes immediately.
base::ScopedObservation<UrlKeyedDataCollectionConsentHelper, ConsentThrottle>
handle_observation_{this};
// Requests waiting for the consent throttle to initialize. Requests are
// stored in the queue in order of their arrival.
std::vector<RequestCallback> enqueued_request_callbacks_;
// Timer used to periodically process unanswered enqueued requests, and
// respond to them in the negative.
base::OneShotTimer request_processing_timer_;
};
} // namespace unified_consent
#endif // COMPONENTS_UNIFIED_CONSENT_CONSENT_THROTTLE_H_
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