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// Copyright 2019 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_OMNIBOX_BROWSER_AUTOCOMPLETE_PROVIDER_DEBOUNCER_H_
#define COMPONENTS_OMNIBOX_BROWSER_AUTOCOMPLETE_PROVIDER_DEBOUNCER_H_
#include "base/functional/callback.h"
#include "base/time/time.h"
#include "base/timer/timer.h"
// Debounces a method call, i.e. throttles its call rate by delaying its
// invocations and cancelling pending ones when new ones are requested. Each
// instance should be used in a single thread to avoid bad `callback_`.
class AutocompleteProviderDebouncer {
public:
AutocompleteProviderDebouncer(bool from_last_run, int delay_ms);
~AutocompleteProviderDebouncer();
// Request `callback` to be invoked after the debouncing delay. If called
// while a previous request is still pending, the previous request will be
// cancelled.
void RequestRun(base::OnceCallback<void()> callback);
// Cancels any pending request.
void CancelRequest();
// If there's a pending `callback` request, runs it immediately; otherwise,
// does nothing.
void FlushRequest();
private:
void Run();
// Whether debounce delays are calculated since `time_last_run_` or the last
// invocation of `RequestRun`.
bool from_last_run_ = false;
// The debounce delay.
int delay_ms_ = 0;
// Tracks when to next invoke `callback_`.
base::OneShotTimer timer_;
// The last time `Run` was invoked.
base::TimeTicks time_last_run_;
// The callback to invoke once `timer_` expires.
base::OnceCallback<void()> callback_;
};
#endif // COMPONENTS_OMNIBOX_BROWSER_AUTOCOMPLETE_PROVIDER_DEBOUNCER_H_
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