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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.
#include "components/reporting/util/disconnectable_client.h"
#include <limits>
#include <memory>
#include <queue>
#include <utility>
#include "base/containers/fixed_flat_map.h"
#include "base/feature_list.h"
#include "base/functional/callback.h"
#include "base/logging.h"
#include "base/memory/scoped_refptr.h"
#include "base/memory/weak_ptr.h"
#include "base/metrics/field_trial_params.h"
#include "base/metrics/histogram_functions.h"
#include "base/sequence_checker.h"
#include "base/task/sequenced_task_runner.h"
#include "components/reporting/util/reporting_errors.h"
#include "components/reporting/util/status.h"
namespace reporting {
// The feature is enabled by default, to be disabled as a kill switch only
// (if it is disabled, all jobs are permitted to run, no limit)
BASE_FEATURE(kEnableReportingDelegateJobsLimit,
"EnableReportingDelegateJobsLimit",
base::FEATURE_ENABLED_BY_DEFAULT);
constexpr char kMaxDelegatesRunningParamName[] = "max_running";
const base::FeatureParam<size_t> kMaxDelegatesRunning{
&kEnableReportingDelegateJobsLimit, kMaxDelegatesRunningParamName, 10};
namespace {
size_t max_delegate_jobs_running() {
if (!base::FeatureList::IsEnabled(kEnableReportingDelegateJobsLimit)) {
return std::numeric_limits<size_t>::max();
}
return kMaxDelegatesRunning.Get();
}
} // namespace
DisconnectableClient::DisconnectableClient(
scoped_refptr<base::SequencedTaskRunner> task_runner)
: task_runner_(task_runner) {}
DisconnectableClient::~DisconnectableClient() {
DCHECK_CALLED_ON_VALID_SEQUENCE(sequence_checker_);
SetAvailability(/*is_available=*/false);
}
// static
const base::Feature& DisconnectableClient::ReportingDelegateJobsLimitFeature() {
return kEnableReportingDelegateJobsLimit;
}
// static
const char* DisconnectableClient::MaxDelegatesRunningParamName() {
return kMaxDelegatesRunningParamName;
}
void DisconnectableClient::MaybeMakeCall(std::unique_ptr<Delegate> delegate) {
DCHECK_CALLED_ON_VALID_SEQUENCE(sequence_checker_);
// Bail out, if missive daemon is not available over dBus.
if (!is_available_) {
delegate->Respond(Status(error::UNAVAILABLE,
disconnectable_client::kErrorServiceUnavailable));
base::UmaHistogramEnumeration(
reporting::kUmaUnavailableErrorReason,
UnavailableErrorReason::CLIENT_NOT_CONNECTED_TO_MISSIVE,
UnavailableErrorReason::MAX_VALUE);
return;
}
// Check whether there are too many delegates running already.
if (outstanding_delegates_.size() >= max_delegate_jobs_running()) {
// Delay.
delayed_delegates_.push(std::move(delegate));
return;
}
// Otherwise call it.
MakeCall(std::move(delegate));
}
void DisconnectableClient::MakeCall(std::unique_ptr<Delegate> delegate) {
DCHECK_CALLED_ON_VALID_SEQUENCE(sequence_checker_);
// Bail out, if missive daemon is not available over dBus.
if (!is_available_) {
delegate->Respond(Status(error::UNAVAILABLE,
disconnectable_client::kErrorServiceUnavailable));
base::UmaHistogramEnumeration(
reporting::kUmaUnavailableErrorReason,
UnavailableErrorReason::CLIENT_NOT_CONNECTED_TO_MISSIVE,
UnavailableErrorReason::MAX_VALUE);
return;
}
// Add the delegate to the map.
const auto id = ++last_id_;
auto res = outstanding_delegates_.emplace(id, std::move(delegate));
// Make a call, resume on CallResponded, when response is received.
res.first->second->DoCall(base::BindOnce(&DisconnectableClient::CallResponded,
weak_ptr_factory_.GetWeakPtr(), id));
}
void DisconnectableClient::CallResponded(uint64_t id) {
DCHECK_CALLED_ON_VALID_SEQUENCE(sequence_checker_);
auto it = outstanding_delegates_.find(id);
if (it == outstanding_delegates_.end()) {
// Callback has already been removed, no action needed.
return;
}
// Remove delegate from |outstanding_delegates_|.
const auto delegate = std::move(it->second);
outstanding_delegates_.erase(it);
// Respond through the |delegate|.
delegate->Respond(Status::StatusOK());
// If there are more delegates in queue, run the first one or more.
// Note that we check the count again, since `max_delegate_jobs_running`
// could have changed.
while (!delayed_delegates_.empty() &&
outstanding_delegates_.size() < max_delegate_jobs_running()) {
MakeCall(std::move(delayed_delegates_.front()));
delayed_delegates_.pop();
}
}
void DisconnectableClient::SetAvailability(bool is_available) {
DCHECK_CALLED_ON_VALID_SEQUENCE(sequence_checker_);
is_available_ = is_available;
LOG(WARNING) << "Service became " << (is_available_ ? "" : "un")
<< "available";
if (is_available_) {
// Start delayed calls, if there are spots.
while (!delayed_delegates_.empty() &&
outstanding_delegates_.size() < max_delegate_jobs_running()) {
MakeCall(std::move(delayed_delegates_.front()));
delayed_delegates_.pop();
}
} else {
// Cancel all pending calls.
while (!outstanding_delegates_.empty()) {
// Remove the first delegate from |outstanding_delegates_|.
const auto delegate = std::move(outstanding_delegates_.begin()->second);
outstanding_delegates_.erase(outstanding_delegates_.begin());
// Respond through the |delegate|.
delegate->Respond(Status(
error::UNAVAILABLE, disconnectable_client::kErrorServiceUnavailable));
base::UmaHistogramEnumeration(
reporting::kUmaUnavailableErrorReason,
UnavailableErrorReason::CLIENT_NOT_CONNECTED_TO_MISSIVE,
UnavailableErrorReason::MAX_VALUE);
}
// Cancel all delayed calls.
while (!delayed_delegates_.empty()) {
// Remove the first delegate from |delayed_delegates_|.
const auto delegate = std::move(delayed_delegates_.front());
delayed_delegates_.pop();
// Respond through the |delegate|.
delegate->Respond(Status(
error::UNAVAILABLE, disconnectable_client::kErrorServiceUnavailable));
base::UmaHistogramEnumeration(
reporting::kUmaUnavailableErrorReason,
UnavailableErrorReason::CLIENT_NOT_CONNECTED_TO_MISSIVE,
UnavailableErrorReason::MAX_VALUE);
}
}
}
} // namespace reporting
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