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// Copyright 2012 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_METRICS_HISTOGRAM_CONTROLLER_H_
#define COMPONENTS_METRICS_HISTOGRAM_CONTROLLER_H_
#include <map>
#include <string>
#include <vector>
#include "base/component_export.h"
#include "base/memory/raw_ptr.h"
#include "base/memory/singleton.h"
#include "base/memory/unsafe_shared_memory_region.h"
#include "base/sequence_checker.h"
#include "base/timer/timer.h"
#include "components/metrics/histogram_child_process.h"
#include "components/metrics/public/mojom/histogram_fetcher.mojom.h"
#include "mojo/public/cpp/bindings/remote.h"
namespace metrics {
class HistogramSubscriber;
// HistogramController is used on the browser process to collect histogram data.
// Only one thread (typically the UI thread) is allowed to interact with the
// HistogramController object.
class COMPONENT_EXPORT(METRICS) HistogramController {
public:
// Returns the HistogramController object for the current process, or null if
// none.
static HistogramController* GetInstance();
// Normally instantiated when the child process is launched. Only one instance
// should be created per process.
HistogramController();
HistogramController(const HistogramController&) = delete;
HistogramController& operator=(const HistogramController&) = delete;
virtual ~HistogramController();
// Register the subscriber so that it will be called when for example
// OnHistogramDataCollected is returning histogram data from a child process.
void Register(HistogramSubscriber* subscriber);
// Unregister the subscriber so that it will not be called when for example
// OnHistogramDataCollected is returning histogram data from a child process.
// Safe to call even if caller is not the current subscriber.
void Unregister(const HistogramSubscriber* subscriber);
// Contact all processes and get their histogram data.
void GetHistogramData(int sequence_number);
enum class ChildProcessMode {
// This child process should be included when gathering non-persistent
// histogram data from child processes.
kGetHistogramData,
// This child process should only be included in pings, but histogram data
// should not be collected.
kPingOnly,
};
void SetHistogramMemory(HistogramChildProcess* host,
base::UnsafeSharedMemoryRegion shared_region,
ChildProcessMode mode);
// Some hosts can be re-used before Mojo recognizes that their connections
// are invalid because the previous child process died.
void NotifyChildDied(HistogramChildProcess* host);
private:
friend struct base::LeakySingletonTraits<HistogramController>;
raw_ptr<HistogramSubscriber> subscriber_;
void InsertChildHistogramFetcherInterface(
HistogramChildProcess* host,
mojo::Remote<mojom::ChildHistogramFetcher> child_histogram_fetcher,
ChildProcessMode mode);
// Calls PingChildProcess() on ~10% of child processes. Not all child
// processes are pinged so as to avoid possibly "waking up" too many and
// causing unnecessary work.
void PingChildProcesses();
// Pings a child process through its |fetcher|. This does nothing except emit
// histograms (both on the browser process and the child process), with the
// goal of quantifying the amount of histogram samples lost from child
// processes.
void PingChildProcess(mojom::ChildHistogramFetcherProxy* fetcher,
mojom::UmaPingCallSource call_source);
// Callback for when a child process has received a ping (see
// PingChildProcess()).
void Pong(mojom::UmaPingCallSource call_source);
void RemoveChildHistogramFetcherInterface(
MayBeDangling<HistogramChildProcess> host);
// Records the histogram data collected from a child process.
void OnHistogramDataCollected(
int sequence_number,
const std::vector<std::string>& pickled_histograms);
struct ChildHistogramFetcher;
using ChildHistogramFetcherMap =
std::map<HistogramChildProcess*, ChildHistogramFetcher>;
ChildHistogramFetcherMap child_histogram_fetchers_;
// Used to call PingAllChildProcesses() every 5 minutes.
base::RepeatingTimer timer_;
SEQUENCE_CHECKER(sequence_checker_);
};
} // namespace metrics
#endif // COMPONENTS_METRICS_HISTOGRAM_CONTROLLER_H_
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