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// Copyright 2024 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#include "content/browser/renderer_host/navigation_transitions/navigation_transition_config.h"
#include "base/system/sys_info.h"
#include "base/time/time.h"
#include "content/public/common/content_features.h"
#include "third_party/blink/public/common/features.h"
#include "ui/display/screen.h"
namespace content {
namespace {
const base::FeatureParam<int> kMaxScreenshotCount{
&blink::features::kBackForwardTransitions, "max-screenshot-count", 20};
const base::FeatureParam<int> kMaxCacheSize{
&blink::features::kBackForwardTransitions, "max-cache-size", -1};
const base::FeatureParam<int> kMinRequiredPhysicalRamMb{
&blink::features::kBackForwardTransitions, "min-required-physical-ram-mb",
0};
const base::FeatureParam<double> kPercentageOfRamToUse{
&blink::features::kBackForwardTransitions, "percentage-of-ram-to-use", 2.5};
const base::FeatureParam<base::TimeDelta> kInvisibleCacheCleanupDelay{
&blink::features::kBackForwardTransitions, "invisible-cache-cleanup-delay",
base::Minutes(7)};
// Compression can be done in a best-effort basis to reduce contention.
// Quiescence is defined as no visible page loading and no input being
// processed.
const base::FeatureParam<bool> kCompressScreenshotWhenQuiet{
&blink::features::kBackForwardTransitions, "compress-screenshot-when-quiet",
false};
// SendResult is an expensive operation and the start of a navigation is a busy
// time. Delaying SendResult reduces chances of contention.
// The value can be based on human reaction times and LCP latencies and it can
// be adjusted based on the incidence of the value SentScreenshotRequest in
// Navigation.GestureTransition.CacheHitOrMissReason.
const base::FeatureParam<int> kScreenshotSendResultDelayMs{
&blink::features::kBackForwardTransitions,
"screenshot-send-result-delay-ms", 0};
size_t GetMaxCacheSizeInBytes() {
constexpr int kLowEndMax = 32 * 1024 * 1024; // 32MB
constexpr int kOtherMax = 128 * 1024 * 1024; // 128MB
const size_t default_size =
base::SysInfo::IsLowEndDevice() ? kLowEndMax : kOtherMax;
int size = kMaxCacheSize.Get();
return size < 0 ? default_size : static_cast<size_t>(size);
}
int GetMinRequiredPhysicalRamMb() {
return kMinRequiredPhysicalRamMb.Get();
}
} // namespace
// static
bool NavigationTransitionConfig::AreBackForwardTransitionsEnabled() {
if (base::SysInfo::AmountOfPhysicalMemoryMB() <
GetMinRequiredPhysicalRamMb()) {
return false;
}
return base::FeatureList::IsEnabled(blink::features::kBackForwardTransitions);
}
// static
size_t NavigationTransitionConfig::ComputeCacheSizeInBytes() {
// Assume 4 bytes per pixel. This value estimates the max number of bytes of
// the physical screen's uncompressed bitmap.
size_t display_size_in_bytes = 0;
for (const auto& display : display::Screen::GetScreen()->GetAllDisplays()) {
display_size_in_bytes =
std::max(display_size_in_bytes,
static_cast<size_t>(4 * display.GetSizeInPixel().Area64()));
}
size_t memory_required_for_max_screenshots =
display_size_in_bytes * kMaxScreenshotCount.Get();
size_t physical_memory_budget =
(base::SysInfo::AmountOfPhysicalMemory() * kPercentageOfRamToUse.Get()) /
100;
physical_memory_budget =
std::min(physical_memory_budget, GetMaxCacheSizeInBytes());
physical_memory_budget =
std::min(physical_memory_budget, memory_required_for_max_screenshots);
// We should at least be able to cache one uncompressed screenshot.
physical_memory_budget =
std::max(display_size_in_bytes, physical_memory_budget);
return physical_memory_budget;
}
// static
base::TimeDelta
NavigationTransitionConfig::GetCleanupDelayForInvisibleCaches() {
return kInvisibleCacheCleanupDelay.Get();
}
// static
bool NavigationTransitionConfig::ShouldCompressScreenshotWhenQuiet() {
return kCompressScreenshotWhenQuiet.Get();
}
// static
base::TimeDelta NavigationTransitionConfig::ScreenshotSendResultDelay() {
return base::Milliseconds(kScreenshotSendResultDelayMs.Get());
}
} // namespace content
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