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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 <array>
#include <string_view>
#include "base/base_paths.h"
#include "base/files/file_util.h"
#include "base/path_service.h"
#include "base/threading/platform_thread.h"
#include "chrome/browser/extensions/chrome_test_extension_loader.h"
#include "chrome/browser/extensions/extension_browsertest.h"
#include "chrome/browser/profiles/profile.h"
#include "chrome/browser/ui/browser.h"
#include "chrome/browser/ui/browser_commands.h"
#include "components/metrics/content/subprocess_metrics_provider.h"
#include "content/public/test/browser_test.h"
#include "content/public/test/browser_test_utils.h"
#include "third_party/blink/public/common/switches.h"
class WasmExtensionCachingBrowserTest
: public extensions::ExtensionBrowserTest {
public:
WasmExtensionCachingBrowserTest() = default;
~WasmExtensionCachingBrowserTest() override = default;
static constexpr std::string_view kHistogram = "V8.WasmCodeCaching";
// The enum values need to match "WasmCodeCaching" in
// tools/metrics/histograms/metadata/v8/enums.xml.
enum WasmCodeCaching {
kMiss = 0,
kHit = 1,
kInvalidCacheEntry = 2,
kNoCacheHandler = 3,
kMaxValue = kNoCacheHandler
};
static constexpr std::array kWasmCodeCachingBucketNames = {
"kMiss", "kHit", "kInvalidCacheEntry", "kNoCacheHandler"};
const base::FilePath& GetExtensionDir() {
if (!tmp_dir_.IsValid()) {
CHECK(tmp_dir_.CreateUniqueTempDir());
}
return tmp_dir_.GetPath();
}
int GetBucketCount(WasmCodeCaching bucket) const {
return histogram_tester_.GetBucketCount(kHistogram, bucket);
}
int FetchAndAccumulateHistogram() {
content::FetchHistogramsFromChildProcesses();
metrics::SubprocessMetricsProvider::MergeHistogramDeltasForTesting();
// Log and sum up the samples. The logging will help diagnose failures or
// flakes.
auto buckets = histogram_tester_.GetAllSamples(kHistogram);
int total_samples = 0;
LOG(INFO) << "Histogram '" << kHistogram << "': ";
for (auto& bucket : buckets) {
LOG(INFO) << kWasmCodeCachingBucketNames[bucket.min] << ": "
<< bucket.count << "\t";
total_samples += bucket.count;
}
return total_samples;
}
// Fetch the `bucket` from the `histogram` in every renderer process until
// reaching, but not exceeding, `expected_samples`.
void WaitForHistogramSamples(std::string_view histogram,
int expected_samples) {
// We sleep for an increasing amount of time for the background task to
// finish.
int millis_sleep = 100;
while (true) {
LOG(INFO) << "Fetching histograms, waiting for " << expected_samples
<< " samples...";
int total_samples = FetchAndAccumulateHistogram();
if (total_samples == expected_samples) {
return;
}
CHECK_LT(total_samples, expected_samples);
base::PlatformThread::Sleep(base::Milliseconds(millis_sleep));
// Increase sleep time, but never sleep more than 5 seconds.
millis_sleep = std::min(5000, millis_sleep * 2);
}
}
private:
// JS flags:
// --allow-natives-syntax: Enables the use of (internal) runtime
// functions like `%IsLiftoffFunction`.
// --wasm-caching-threshold=1: Trigger caching as soon as any TurboFan
// code is available.
// --wasm-caching-hard-threshold=1: Trigger caching immediately, not after a
// delay.
// --wasm-tiering-budget=1: Trigger tier-up earlier.
void SetUpCommandLine(base::CommandLine* command_line) override {
command_line->AppendSwitchASCII(blink::switches::kJavaScriptFlags,
"--allow-natives-syntax"
" --wasm-caching-threshold=1"
" --wasm-caching-hard-threshold=1"
" --wasm-tiering-budget=1");
ExtensionBrowserTest::SetUpCommandLine(command_line);
}
base::ScopedTempDir tmp_dir_;
base::HistogramTester histogram_tester_;
};
// The `large.wasm` file is very large: 2.5MB. To avoid increasing the git
// repository, we prefer borrowing it from web_tests.
base::FilePath LargeWasmPath() {
base::FilePath root_path;
CHECK(base::PathService::Get(base::DIR_SRC_TEST_DATA_ROOT, &root_path));
return root_path.Append(FILE_PATH_LITERAL(
"third_party/blink/web_tests/http/tests/wasm/resources/large.wasm"));
}
// Test that we cache streaming compiled/instantiated Wasm modules in
// extensions. We have to wait until caching of the module happens and the
// histogram is populated.
IN_PROC_BROWSER_TEST_F(WasmExtensionCachingBrowserTest, CacheWasmExtensions) {
base::ScopedAllowBlockingForTesting allow_blocking;
CHECK(base::CopyFile(LargeWasmPath(),
GetExtensionDir().AppendASCII("large.wasm")));
base::WriteFile(GetExtensionDir().AppendASCII("service_worker_background.js"),
R"(
function execute_wasm(instance) {
let has_unoptimized = false;
for (export_name in instance.exports) {
const func = instance.exports[export_name];
func(1, 2, 4);
has_unoptimized ||= %IsLiftoffFunction(func);
}
if (has_unoptimized) {
setTimeout(() => execute_wasm(instance), 1);
}
}
chrome.tabs.onCreated.addListener(() => {
// Run all functions until there are no unoptimized functions left.
WebAssembly.instantiateStreaming(fetch("large.wasm")).then(
({instance}) => execute_wasm(instance));
});
)");
base::WriteFile(GetExtensionDir().AppendASCII("manifest.json"), R"({
"name": "foo",
"description": "foo",
"version": "0.1",
"manifest_version": 2,
"content_security_policy": "script-src 'self' 'unsafe-eval'; object-src 'self'",
"background": {
"service_worker": "service_worker_background.js"
}
})");
// After loading the extension, no WebAssembly has been executed.
extensions::ChromeTestExtensionLoader loader(browser()->profile());
LOG(INFO) << "Loading extension, expecting zero misses / hits";
loader.LoadExtension(GetExtensionDir());
WaitForHistogramSamples(kHistogram, 0);
CHECK_EQ(0, GetBucketCount(kMiss));
CHECK_EQ(0, GetBucketCount(kHit));
// Open up to 10 tabs, with some waiting in between. We should eventually see
// a cache hit.
// Typically (on a reasonably fast machine) the first tab creates the cache
// entry and the second tab consumes it. Very slow machines might require a
// few more loads.
for (int num_tabs = 1; num_tabs <= 10; ++num_tabs) {
LOG(INFO) << "Opening new tab #" << num_tabs;
chrome::NewTab(browser());
// Wait until we got a total of `num_tabs` many samples.
WaitForHistogramSamples(kHistogram, num_tabs);
// If there was a hit, we are happy (and done).
if (GetBucketCount(kHit)) {
return;
}
CHECK_EQ(num_tabs, GetBucketCount(kMiss));
// Before opening the next tab, wait for some (increasing) time.
// The total maximum waiting time is 1 + 2 + ... + 10 = 55 seconds.
base::PlatformThread::Sleep(base::Seconds(num_tabs));
}
FAIL() << "Failure: No cache hits";
}
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