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// Copyright 2020 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#include "chrome/browser/performance_manager/mechanisms/page_discarder.h"
#include <utility>
#include "base/memory/weak_ptr.h"
#include "base/metrics/histogram_functions.h"
#include "base/not_fatal_until.h"
#include "chrome/browser/performance_manager/public/user_tuning/user_tuning_utils.h"
#include "chrome/browser/resource_coordinator/tab_lifecycle_unit.h"
#include "chrome/browser/resource_coordinator/tab_lifecycle_unit_external.h"
#include "components/performance_manager/public/graph/page_node.h"
#include "content/public/browser/web_contents.h"
#include "third_party/abseil-cpp/absl/cleanup/cleanup.h"
namespace performance_manager::mechanism {
namespace {
// These values are persisted to logs. Entries should not be renumbered and
// numeric values should never be reused.
// LINT.IfChange(DiscardPageOnUIThreadOutcome)
enum class DiscardPageOnUIThreadOutcome {
kSuccess = 0,
kNoContents = 1,
kDiscardTabFailure = 2,
kMaxValue = kDiscardTabFailure
};
// LINT.ThenChange(/tools/metrics/histograms/metadata/tab/enums.xml:DiscardPageOnUIThreadOutcome)
} // namespace
std::optional<uint64_t> PageDiscarder::DiscardPageNode(
const PageNode* page_node,
resource_coordinator::LifecycleUnitDiscardReason discard_reason) {
base::WeakPtr<content::WebContents> contents = page_node->GetWebContents();
std::optional<DiscardPageOnUIThreadOutcome> outcome;
absl::Cleanup record_discard_outcome = [&]() {
CHECK(outcome.has_value(), base::NotFatalUntil::M140);
base::UmaHistogramEnumeration("Discarding.DiscardPageOnUIThreadOutcome",
outcome.value());
};
CHECK(contents, base::NotFatalUntil::M140);
if (!contents) {
outcome = DiscardPageOnUIThreadOutcome::kNoContents;
return std::nullopt;
}
auto* lifecycle_unit =
resource_coordinator::TabLifecycleUnitSource::GetTabLifecycleUnitExternal(
contents.get());
// This function is only called with `PageNode`s of type `kTab`, so there
// should be a LifecycleUnit.
CHECK(lifecycle_unit, base::NotFatalUntil::M140);
uint64_t memory_footprint_estimate =
user_tuning::GetDiscardedMemoryEstimateForPage(page_node);
if (!lifecycle_unit->DiscardTab(discard_reason, memory_footprint_estimate)) {
outcome = DiscardPageOnUIThreadOutcome::kDiscardTabFailure;
return std::nullopt;
}
outcome = DiscardPageOnUIThreadOutcome::kSuccess;
return memory_footprint_estimate;
}
} // namespace performance_manager::mechanism
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