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gecko-dev/startupcache/StartupCache.cpp

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/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
/* vim: set ts=8 sts=2 et sw=2 tw=80: */
/* This Source Code Form is subject to the terms of the Mozilla Public
* License, v. 2.0. If a copy of the MPL was not distributed with this
* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
#include "prio.h"
#include "PLDHashTable.h"
#include "mozilla/IOInterposer.h"
#include "mozilla/AutoMemMap.h"
#include "mozilla/IOBuffers.h"
#include "mozilla/MemoryReporting.h"
#include "mozilla/MemUtils.h"
#include "mozilla/MmapFaultHandler.h"
#include "mozilla/ResultExtensions.h"
#include "mozilla/scache/StartupCache.h"
#include "mozilla/ScopeExit.h"
#include "nsClassHashtable.h"
#include "nsComponentManagerUtils.h"
#include "nsCRT.h"
#include "nsDirectoryServiceUtils.h"
#include "nsIClassInfo.h"
#include "nsIFile.h"
#include "nsIObserver.h"
#include "nsIOutputStream.h"
#include "nsISupports.h"
#include "nsITimer.h"
#include "mozilla/Omnijar.h"
#include "prenv.h"
#include "mozilla/Telemetry.h"
#include "nsThreadUtils.h"
#include "nsXULAppAPI.h"
#include "nsIProtocolHandler.h"
#include "GeckoProfiler.h"
#include "nsAppRunner.h"
#include "xpcpublic.h"
#if defined(XP_WIN)
# include <windows.h>
#endif
#ifdef IS_BIG_ENDIAN
# define SC_ENDIAN "big"
#else
# define SC_ENDIAN "little"
#endif
#if PR_BYTES_PER_WORD == 4
# define SC_WORDSIZE "4"
#else
# define SC_WORDSIZE "8"
#endif
using namespace mozilla::Compression;
namespace mozilla {
namespace scache {
MOZ_DEFINE_MALLOC_SIZE_OF(StartupCacheMallocSizeOf)
NS_IMETHODIMP
StartupCache::CollectReports(nsIHandleReportCallback* aHandleReport,
nsISupports* aData, bool aAnonymize) {
MOZ_COLLECT_REPORT(
"explicit/startup-cache/mapping", KIND_NONHEAP, UNITS_BYTES,
mCacheData.nonHeapSizeOfExcludingThis(),
"Memory used to hold the mapping of the startup cache from file. "
"This memory is likely to be swapped out shortly after start-up.");
MOZ_COLLECT_REPORT("explicit/startup-cache/data", KIND_HEAP, UNITS_BYTES,
HeapSizeOfIncludingThis(StartupCacheMallocSizeOf),
"Memory used by the startup cache for things other than "
"the file mapping.");
return NS_OK;
}
static const uint8_t MAGIC[] = "startupcache0002";
// This is a heuristic value for how much to reserve for mTable to avoid
// rehashing. This is not a hard limit in release builds, but it is in
// debug builds as it should be stable. If we exceed this number we should
// just increase it.
static const size_t STARTUP_CACHE_RESERVE_CAPACITY = 450;
// This is a hard limit which we will assert on, to ensure that we don't
// have some bug causing runaway cache growth.
static const size_t STARTUP_CACHE_MAX_CAPACITY = 5000;
// Not const because we change it for gtests.
static uint8_t STARTUP_CACHE_WRITE_TIMEOUT = 60;
#define STARTUP_CACHE_NAME "startupCache." SC_WORDSIZE "." SC_ENDIAN
static inline Result<Ok, nsresult> Write(PRFileDesc* fd, const void* data,
int32_t len) {
if (PR_Write(fd, data, len) != len) {
return Err(NS_ERROR_FAILURE);
}
return Ok();
}
static inline Result<Ok, nsresult> Seek(PRFileDesc* fd, int32_t offset) {
if (PR_Seek(fd, offset, PR_SEEK_SET) == -1) {
return Err(NS_ERROR_FAILURE);
}
return Ok();
}
static nsresult MapLZ4ErrorToNsresult(size_t aError) {
return NS_ERROR_FAILURE;
}
StartupCache* StartupCache::GetSingletonNoInit() {
return StartupCache::gStartupCache;
}
StartupCache* StartupCache::GetSingleton() {
if (!gStartupCache) {
if (!XRE_IsParentProcess()) {
return nullptr;
}
#ifdef MOZ_DISABLE_STARTUPCACHE
return nullptr;
#else
StartupCache::InitSingleton();
#endif
}
return StartupCache::gStartupCache;
}
void StartupCache::DeleteSingleton() { StartupCache::gStartupCache = nullptr; }
nsresult StartupCache::InitSingleton() {
nsresult rv;
StartupCache::gStartupCache = new StartupCache();
rv = StartupCache::gStartupCache->Init();
if (NS_FAILED(rv)) {
StartupCache::gStartupCache = nullptr;
}
return rv;
}
StaticRefPtr<StartupCache> StartupCache::gStartupCache;
bool StartupCache::gShutdownInitiated;
bool StartupCache::gIgnoreDiskCache;
bool StartupCache::gFoundDiskCacheOnInit;
NS_IMPL_ISUPPORTS(StartupCache, nsIMemoryReporter)
StartupCache::StartupCache()
: mTableLock("StartupCache::mTableLock"),
mDirty(false),
mWrittenOnce(false),
mCurTableReferenced(false),
mRequestedCount(0),
mCacheEntriesBaseOffset(0),
mPrefetchThread(nullptr) {}
StartupCache::~StartupCache() { UnregisterWeakMemoryReporter(this); }
nsresult StartupCache::Init() {
// workaround for bug 653936
nsCOMPtr<nsIProtocolHandler> jarInitializer(
do_GetService(NS_NETWORK_PROTOCOL_CONTRACTID_PREFIX "jar"));
nsresult rv;
if (mozilla::RunningGTest()) {
STARTUP_CACHE_WRITE_TIMEOUT = 3;
}
// This allows to override the startup cache filename
// which is useful from xpcshell, when there is no ProfLDS directory to keep
// cache in.
char* env = PR_GetEnv("MOZ_STARTUP_CACHE");
if (env && *env) {
rv = NS_NewLocalFile(NS_ConvertUTF8toUTF16(env), false,
getter_AddRefs(mFile));
} else {
nsCOMPtr<nsIFile> file;
rv = NS_GetSpecialDirectory("ProfLDS", getter_AddRefs(file));
if (NS_FAILED(rv)) {
// return silently, this will fail in mochitests's xpcshell process.
return rv;
}
rv = file->AppendNative("startupCache"_ns);
NS_ENSURE_SUCCESS(rv, rv);
// Try to create the directory if it's not there yet
rv = file->Create(nsIFile::DIRECTORY_TYPE, 0777);
if (NS_FAILED(rv) && rv != NS_ERROR_FILE_ALREADY_EXISTS) return rv;
rv = file->AppendNative(nsLiteralCString(STARTUP_CACHE_NAME));
NS_ENSURE_SUCCESS(rv, rv);
mFile = file;
}
NS_ENSURE_TRUE(mFile, NS_ERROR_UNEXPECTED);
mObserverService = do_GetService("@mozilla.org/observer-service;1");
if (!mObserverService) {
NS_WARNING("Could not get observerService.");
return NS_ERROR_UNEXPECTED;
}
mListener = new StartupCacheListener();
rv = mObserverService->AddObserver(mListener, NS_XPCOM_SHUTDOWN_OBSERVER_ID,
false);
NS_ENSURE_SUCCESS(rv, rv);
rv = mObserverService->AddObserver(mListener, "startupcache-invalidate",
false);
NS_ENSURE_SUCCESS(rv, rv);
auto result = LoadArchive();
rv = result.isErr() ? result.unwrapErr() : NS_OK;
gFoundDiskCacheOnInit = rv != NS_ERROR_FILE_NOT_FOUND;
// Sometimes we don't have a cache yet, that's ok.
// If it's corrupted, just remove it and start over.
if (gIgnoreDiskCache || (NS_FAILED(rv) && rv != NS_ERROR_FILE_NOT_FOUND)) {
NS_WARNING("Failed to load startupcache file correctly, removing!");
InvalidateCache();
}
RegisterWeakMemoryReporter(this);
mDecompressionContext = MakeUnique<LZ4FrameDecompressionContext>(true);
return NS_OK;
}
void StartupCache::StartPrefetchMemoryThread() {
// XXX: It would be great for this to not create its own thread, unfortunately
// there doesn't seem to be an existing thread that makes sense for this, so
// barring a coordinated global scheduling system this is the best we get.
mPrefetchThread = PR_CreateThread(
PR_USER_THREAD, StartupCache::ThreadedPrefetch, this, PR_PRIORITY_NORMAL,
PR_GLOBAL_THREAD, PR_JOINABLE_THREAD, 256 * 1024);
}
/**
* LoadArchive can only be called from the main thread.
*/
Result<Ok, nsresult> StartupCache::LoadArchive() {
MOZ_ASSERT(NS_IsMainThread(), "Can only load startup cache on main thread");
if (gIgnoreDiskCache) return Err(NS_ERROR_FAILURE);
MOZ_TRY(mCacheData.init(mFile));
auto size = mCacheData.size();
if (CanPrefetchMemory()) {
StartPrefetchMemoryThread();
}
uint32_t headerSize;
if (size < sizeof(MAGIC) + sizeof(headerSize)) {
return Err(NS_ERROR_UNEXPECTED);
}
auto data = mCacheData.get<uint8_t>();
auto end = data + size;
MMAP_FAULT_HANDLER_BEGIN_BUFFER(data.get(), size)
if (memcmp(MAGIC, data.get(), sizeof(MAGIC))) {
return Err(NS_ERROR_UNEXPECTED);
}
data += sizeof(MAGIC);
headerSize = LittleEndian::readUint32(data.get());
data += sizeof(headerSize);
if (headerSize > end - data) {
MOZ_ASSERT(false, "StartupCache file is corrupt.");
return Err(NS_ERROR_UNEXPECTED);
}
Range<uint8_t> header(data, data + headerSize);
data += headerSize;
mCacheEntriesBaseOffset = sizeof(MAGIC) + sizeof(headerSize) + headerSize;
{
if (!mTable.reserve(STARTUP_CACHE_RESERVE_CAPACITY)) {
return Err(NS_ERROR_UNEXPECTED);
}
auto cleanup = MakeScopeExit([&]() {
WaitOnPrefetchThread();
mTable.clear();
mCacheData.reset();
});
loader::InputBuffer buf(header);
uint32_t currentOffset = 0;
while (!buf.finished()) {
uint32_t offset = 0;
uint32_t compressedSize = 0;
uint32_t uncompressedSize = 0;
nsCString key;
buf.codeUint32(offset);
buf.codeUint32(compressedSize);
buf.codeUint32(uncompressedSize);
buf.codeString(key);
if (offset + compressedSize > end - data) {
MOZ_ASSERT(false, "StartupCache file is corrupt.");
return Err(NS_ERROR_UNEXPECTED);
}
// Make sure offsets match what we'd expect based on script ordering and
// size, as a basic sanity check.
if (offset != currentOffset) {
return Err(NS_ERROR_UNEXPECTED);
}
currentOffset += compressedSize;
// We could use mTable.putNew if we knew the file we're loading weren't
// corrupt. However, we don't know that, so check if the key already
// exists. If it does, we know the file must be corrupt.
decltype(mTable)::AddPtr p = mTable.lookupForAdd(key);
if (p) {
return Err(NS_ERROR_UNEXPECTED);
}
if (!mTable.add(
p, key,
StartupCacheEntry(offset, compressedSize, uncompressedSize))) {
return Err(NS_ERROR_UNEXPECTED);
}
}
if (buf.error()) {
return Err(NS_ERROR_UNEXPECTED);
}
cleanup.release();
}
MMAP_FAULT_HANDLER_CATCH(Err(NS_ERROR_UNEXPECTED))
return Ok();
}
bool StartupCache::HasEntry(const char* id) {
AUTO_PROFILER_LABEL("StartupCache::HasEntry", OTHER);
MOZ_ASSERT(NS_IsMainThread(), "Startup cache only available on main thread");
return mTable.has(nsDependentCString(id));
}
nsresult StartupCache::GetBuffer(const char* id, const char** outbuf,
uint32_t* length) {
AUTO_PROFILER_LABEL("StartupCache::GetBuffer", OTHER);
NS_ASSERTION(NS_IsMainThread(),
"Startup cache only available on main thread");
Telemetry::LABELS_STARTUP_CACHE_REQUESTS label =
Telemetry::LABELS_STARTUP_CACHE_REQUESTS::Miss;
auto telemetry =
MakeScopeExit([&label] { Telemetry::AccumulateCategorical(label); });
decltype(mTable)::Ptr p = mTable.lookup(nsDependentCString(id));
if (!p) {
return NS_ERROR_NOT_AVAILABLE;
}
auto& value = p->value();
if (value.mData) {
label = Telemetry::LABELS_STARTUP_CACHE_REQUESTS::HitMemory;
} else {
if (!mCacheData.initialized()) {
return NS_ERROR_NOT_AVAILABLE;
}
#ifdef DEBUG
// It should be impossible for a write to be pending here. This is because
// we just checked mCacheData.initialized(), and this is reset before
// writing to the cache. It's not re-initialized unless we call
// LoadArchive(), either from Init() (which must have already happened) or
// InvalidateCache(). InvalidateCache() locks the mutex, so a write can't be
// happening. Really, we want to MOZ_ASSERT(!mTableLock.IsLocked()) here,
// but there is no such method. So we hack around by attempting to gain the
// lock. This should always succeed; if it fails, someone's broken the
// assumptions.
if (!mTableLock.TryLock()) {
MOZ_ASSERT(false, "Could not gain mTableLock - should never happen!");
return NS_ERROR_NOT_AVAILABLE;
}
mTableLock.Unlock();
#endif
size_t totalRead = 0;
size_t totalWritten = 0;
Span<const char> compressed = Span(
mCacheData.get<char>().get() + mCacheEntriesBaseOffset + value.mOffset,
value.mCompressedSize);
value.mData = MakeUnique<char[]>(value.mUncompressedSize);
Span<char> uncompressed = Span(value.mData.get(), value.mUncompressedSize);
MMAP_FAULT_HANDLER_BEGIN_BUFFER(uncompressed.Elements(),
uncompressed.Length())
bool finished = false;
while (!finished) {
auto result = mDecompressionContext->Decompress(
uncompressed.From(totalWritten), compressed.From(totalRead));
if (NS_WARN_IF(result.isErr())) {
value.mData = nullptr;
InvalidateCache();
return NS_ERROR_FAILURE;
}
auto decompressionResult = result.unwrap();
totalRead += decompressionResult.mSizeRead;
totalWritten += decompressionResult.mSizeWritten;
finished = decompressionResult.mFinished;
}
MMAP_FAULT_HANDLER_CATCH(NS_ERROR_FAILURE)
label = Telemetry::LABELS_STARTUP_CACHE_REQUESTS::HitDisk;
}
if (!value.mRequested) {
value.mRequested = true;
value.mRequestedOrder = ++mRequestedCount;
MOZ_ASSERT(mRequestedCount <= mTable.count(),
"Somehow we requested more StartupCache items than exist.");
ResetStartupWriteTimerCheckingReadCount();
}
// Track that something holds a reference into mTable, so we know to hold
// onto it in case the cache is invalidated.
mCurTableReferenced = true;
*outbuf = value.mData.get();
*length = value.mUncompressedSize;
return NS_OK;
}
// Makes a copy of the buffer, client retains ownership of inbuf.
nsresult StartupCache::PutBuffer(const char* id, UniquePtr<char[]>&& inbuf,
uint32_t len) {
NS_ASSERTION(NS_IsMainThread(),
"Startup cache only available on main thread");
if (StartupCache::gShutdownInitiated) {
return NS_ERROR_NOT_AVAILABLE;
}
bool exists = mTable.has(nsDependentCString(id));
if (exists) {
NS_WARNING("Existing entry in StartupCache.");
// Double-caching is undesirable but not an error.
return NS_OK;
}
// Try to gain the table write lock. If the background task to write the
// cache is running, this will fail.
if (!mTableLock.TryLock()) {
return NS_ERROR_NOT_AVAILABLE;
}
auto lockGuard = MakeScopeExit([&] { mTableLock.Unlock(); });
// putNew returns false on alloc failure - in the very unlikely event we hit
// that and aren't going to crash elsewhere, there's no reason we need to
// crash here.
if (mTable.putNew(nsCString(id), StartupCacheEntry(std::move(inbuf), len,
++mRequestedCount))) {
return ResetStartupWriteTimer();
}
MOZ_DIAGNOSTIC_ASSERT(mTable.count() < STARTUP_CACHE_MAX_CAPACITY,
"Too many StartupCache entries.");
return NS_OK;
}
size_t StartupCache::HeapSizeOfIncludingThis(
mozilla::MallocSizeOf aMallocSizeOf) const {
// This function could measure more members, but they haven't been found by
// DMD to be significant. They can be added later if necessary.
size_t n = aMallocSizeOf(this);
n += mTable.shallowSizeOfExcludingThis(aMallocSizeOf);
for (auto iter = mTable.iter(); !iter.done(); iter.next()) {
if (iter.get().value().mData) {
n += aMallocSizeOf(iter.get().value().mData.get());
}
n += iter.get().key().SizeOfExcludingThisIfUnshared(aMallocSizeOf);
}
return n;
}
/**
* WriteToDisk writes the cache out to disk. Callers of WriteToDisk need to call
* WaitOnWriteComplete to make sure there isn't a write
* happening on another thread
*/
Result<Ok, nsresult> StartupCache::WriteToDisk() {
mTableLock.AssertCurrentThreadOwns();
if (!mDirty || mWrittenOnce) {
return Ok();
}
if (!mFile) {
return Err(NS_ERROR_UNEXPECTED);
}
AutoFDClose fd;
MOZ_TRY(mFile->OpenNSPRFileDesc(PR_WRONLY | PR_CREATE_FILE | PR_TRUNCATE,
0644, &fd.rwget()));
nsTArray<std::pair<const nsCString*, StartupCacheEntry*>> entries;
for (auto iter = mTable.iter(); !iter.done(); iter.next()) {
if (iter.get().value().mRequested) {
entries.AppendElement(
std::make_pair(&iter.get().key(), &iter.get().value()));
}
}
if (entries.IsEmpty()) {
return Ok();
}
entries.Sort(StartupCacheEntry::Comparator());
loader::OutputBuffer buf;
for (auto& e : entries) {
auto key = e.first;
auto value = e.second;
auto uncompressedSize = value->mUncompressedSize;
// Set the mHeaderOffsetInFile so we can go back and edit the offset.
value->mHeaderOffsetInFile = buf.cursor();
// Write a 0 offset/compressed size as a placeholder until we get the real
// offset after compressing.
buf.codeUint32(0);
buf.codeUint32(0);
buf.codeUint32(uncompressedSize);
buf.codeString(*key);
}
uint8_t headerSize[4];
LittleEndian::writeUint32(headerSize, buf.cursor());
MOZ_TRY(Write(fd, MAGIC, sizeof(MAGIC)));
MOZ_TRY(Write(fd, headerSize, sizeof(headerSize)));
size_t headerStart = sizeof(MAGIC) + sizeof(headerSize);
size_t dataStart = headerStart + buf.cursor();
MOZ_TRY(Seek(fd, dataStart));
size_t offset = 0;
const size_t chunkSize = 1024 * 16;
LZ4FrameCompressionContext ctx(6, /* aCompressionLevel */
chunkSize, /* aReadBufLen */
true, /* aChecksum */
true); /* aStableSrc */
size_t writeBufLen = ctx.GetRequiredWriteBufferLength();
auto writeBuffer = MakeUnique<char[]>(writeBufLen);
auto writeSpan = Span(writeBuffer.get(), writeBufLen);
for (auto& e : entries) {
auto value = e.second;
value->mOffset = offset;
Span<const char> result;
MOZ_TRY_VAR(result,
ctx.BeginCompressing(writeSpan).mapErr(MapLZ4ErrorToNsresult));
MOZ_TRY(Write(fd, result.Elements(), result.Length()));
offset += result.Length();
for (size_t i = 0; i < value->mUncompressedSize; i += chunkSize) {
size_t size = std::min(chunkSize, value->mUncompressedSize - i);
char* uncompressed = value->mData.get() + i;
MOZ_TRY_VAR(result, ctx.ContinueCompressing(Span(uncompressed, size))
.mapErr(MapLZ4ErrorToNsresult));
MOZ_TRY(Write(fd, result.Elements(), result.Length()));
offset += result.Length();
}
MOZ_TRY_VAR(result, ctx.EndCompressing().mapErr(MapLZ4ErrorToNsresult));
MOZ_TRY(Write(fd, result.Elements(), result.Length()));
offset += result.Length();
value->mCompressedSize = offset - value->mOffset;
MOZ_TRY(Seek(fd, dataStart + offset));
}
for (auto& e : entries) {
auto value = e.second;
uint8_t* headerEntry = buf.Get() + value->mHeaderOffsetInFile;
LittleEndian::writeUint32(headerEntry, value->mOffset);
LittleEndian::writeUint32(headerEntry + sizeof(value->mOffset),
value->mCompressedSize);
}
MOZ_TRY(Seek(fd, headerStart));
MOZ_TRY(Write(fd, buf.Get(), buf.cursor()));
mDirty = false;
mWrittenOnce = true;
return Ok();
}
void StartupCache::InvalidateCache(bool memoryOnly) {
WaitOnPrefetchThread();
// Ensure we're not writing using mTable...
MutexAutoLock unlock(mTableLock);
mWrittenOnce = false;
if (memoryOnly) {
// This should only be called in tests.
auto writeResult = WriteToDisk();
if (NS_WARN_IF(writeResult.isErr())) {
gIgnoreDiskCache = true;
return;
}
}
if (mCurTableReferenced) {
// There should be no way for this assert to fail other than a user manually
// sending startupcache-invalidate messages through the Browser Toolbox.
MOZ_DIAGNOSTIC_ASSERT(xpc::IsInAutomation() || mOldTables.Length() < 10,
"Startup cache invalidated too many times.");
mOldTables.AppendElement(std::move(mTable));
mCurTableReferenced = false;
} else {
mTable.clear();
}
mRequestedCount = 0;
if (!memoryOnly) {
mCacheData.reset();
nsresult rv = mFile->Remove(false);
if (NS_FAILED(rv) && rv != NS_ERROR_FILE_TARGET_DOES_NOT_EXIST &&
rv != NS_ERROR_FILE_NOT_FOUND) {
gIgnoreDiskCache = true;
return;
}
}
gIgnoreDiskCache = false;
auto result = LoadArchive();
if (NS_WARN_IF(result.isErr())) {
gIgnoreDiskCache = true;
}
}
void StartupCache::MaybeInitShutdownWrite() {
if (mTimer) {
mTimer->Cancel();
}
gShutdownInitiated = true;
MaybeWriteOffMainThread();
}
void StartupCache::EnsureShutdownWriteComplete() {
// If we've already written or there's nothing to write,
// we don't need to do anything. This is the common case.
if (mWrittenOnce || (mCacheData.initialized() && !ShouldCompactCache())) {
return;
}
// Otherwise, ensure the write happens. The timer should have been cancelled
// already in MaybeInitShutdownWrite.
if (!mTableLock.TryLock()) {
// Uh oh, we're writing away from the main thread. Wait to gain the lock,
// to ensure the write completes.
mTableLock.Lock();
} else {
// We got the lock. Keep the following in sync with
// MaybeWriteOffMainThread:
WaitOnPrefetchThread();
mDirty = true;
mCacheData.reset();
// Most of this should be redundant given MaybeWriteOffMainThread should
// have run before now.
auto writeResult = WriteToDisk();
Unused << NS_WARN_IF(writeResult.isErr());
// We've had the lock, and `WriteToDisk()` sets mWrittenOnce and mDirty
// when done, and checks for them when starting, so we don't need to do
// anything else.
}
mTableLock.Unlock();
}
void StartupCache::IgnoreDiskCache() {
gIgnoreDiskCache = true;
if (gStartupCache) gStartupCache->InvalidateCache();
}
void StartupCache::WaitOnPrefetchThread() {
if (!mPrefetchThread || mPrefetchThread == PR_GetCurrentThread()) return;
PR_JoinThread(mPrefetchThread);
mPrefetchThread = nullptr;
}
void StartupCache::ThreadedPrefetch(void* aClosure) {
AUTO_PROFILER_REGISTER_THREAD("StartupCache");
NS_SetCurrentThreadName("StartupCache");
mozilla::IOInterposer::RegisterCurrentThread();
StartupCache* startupCacheObj = static_cast<StartupCache*>(aClosure);
uint8_t* buf = startupCacheObj->mCacheData.get<uint8_t>().get();
size_t size = startupCacheObj->mCacheData.size();
MMAP_FAULT_HANDLER_BEGIN_BUFFER(buf, size)
PrefetchMemory(buf, size);
MMAP_FAULT_HANDLER_CATCH()
mozilla::IOInterposer::UnregisterCurrentThread();
}
bool StartupCache::ShouldCompactCache() {
// If we've requested less than 4/5 of the startup cache, then we should
// probably compact it down. This can happen quite easily after the first run,
// which seems to request quite a few more things than subsequent runs.
CheckedInt<uint32_t> threshold = CheckedInt<uint32_t>(mTable.count()) * 4 / 5;
MOZ_RELEASE_ASSERT(threshold.isValid(), "Runaway StartupCache size");
return mRequestedCount < threshold.value();
}
/*
* The write-thread is spawned on a timeout(which is reset with every write).
* This can avoid a slow shutdown.
*/
void StartupCache::WriteTimeout(nsITimer* aTimer, void* aClosure) {
/*
* It is safe to use the pointer passed in aClosure to reference the
* StartupCache object because the timer's lifetime is tightly coupled to
* the lifetime of the StartupCache object; this timer is canceled in the
* StartupCache destructor, guaranteeing that this function runs if and only
* if the StartupCache object is valid.
*/
StartupCache* startupCacheObj = static_cast<StartupCache*>(aClosure);
startupCacheObj->MaybeWriteOffMainThread();
}
/*
* See StartupCache::WriteTimeout above - this is just the non-static body.
*/
void StartupCache::MaybeWriteOffMainThread() {
if (mWrittenOnce) {
return;
}
if (mCacheData.initialized() && !ShouldCompactCache()) {
return;
}
// Keep this code in sync with EnsureShutdownWriteComplete.
WaitOnPrefetchThread();
mDirty = true;
mCacheData.reset();
RefPtr<StartupCache> self = this;
nsCOMPtr<nsIRunnable> runnable =
NS_NewRunnableFunction("StartupCache::Write", [self]() mutable {
MutexAutoLock unlock(self->mTableLock);
auto result = self->WriteToDisk();
Unused << NS_WARN_IF(result.isErr());
});
NS_DispatchBackgroundTask(runnable.forget(), NS_DISPATCH_EVENT_MAY_BLOCK);
}
// We don't want to refcount StartupCache, so we'll just
// hold a ref to this and pass it to observerService instead.
NS_IMPL_ISUPPORTS(StartupCacheListener, nsIObserver)
nsresult StartupCacheListener::Observe(nsISupports* subject, const char* topic,
const char16_t* data) {
StartupCache* sc = StartupCache::GetSingleton();
if (!sc) return NS_OK;
if (strcmp(topic, NS_XPCOM_SHUTDOWN_OBSERVER_ID) == 0) {
// Do not leave the thread running past xpcom shutdown
sc->WaitOnPrefetchThread();
StartupCache::gShutdownInitiated = true;
// Note that we don't do anything special for the background write
// task; we expect the threadpool to finish running any tasks already
// posted to it prior to shutdown. FastShutdown will call
// EnsureShutdownWriteComplete() to ensure any pending writes happen
// in that case.
} else if (strcmp(topic, "startupcache-invalidate") == 0) {
sc->InvalidateCache(data && nsCRT::strcmp(data, u"memoryOnly") == 0);
}
return NS_OK;
}
nsresult StartupCache::GetDebugObjectOutputStream(
nsIObjectOutputStream* aStream, nsIObjectOutputStream** aOutStream) {
NS_ENSURE_ARG_POINTER(aStream);
#ifdef DEBUG
auto* stream = new StartupCacheDebugOutputStream(aStream, &mWriteObjectMap);
NS_ADDREF(*aOutStream = stream);
#else
NS_ADDREF(*aOutStream = aStream);
#endif
return NS_OK;
}
nsresult StartupCache::ResetStartupWriteTimerCheckingReadCount() {
nsresult rv = NS_OK;
if (!mTimer)
mTimer = NS_NewTimer();
else
rv = mTimer->Cancel();
NS_ENSURE_SUCCESS(rv, rv);
// Wait for the specified timeout, then write out the cache.
mTimer->InitWithNamedFuncCallback(
StartupCache::WriteTimeout, this, STARTUP_CACHE_WRITE_TIMEOUT * 1000,
nsITimer::TYPE_ONE_SHOT, "StartupCache::WriteTimeout");
return NS_OK;
}
nsresult StartupCache::ResetStartupWriteTimer() {
mDirty = true;
nsresult rv = NS_OK;
if (!mTimer)
mTimer = NS_NewTimer();
else
rv = mTimer->Cancel();
NS_ENSURE_SUCCESS(rv, rv);
// Wait for the specified timeout, then write out the cache.
mTimer->InitWithNamedFuncCallback(
StartupCache::WriteTimeout, this, STARTUP_CACHE_WRITE_TIMEOUT * 1000,
nsITimer::TYPE_ONE_SHOT, "StartupCache::WriteTimeout");
return NS_OK;
}
// Used only in tests:
bool StartupCache::StartupWriteComplete() {
// Need to have written to disk and not added new things since;
return !mDirty && mWrittenOnce;
}
// StartupCacheDebugOutputStream implementation
#ifdef DEBUG
NS_IMPL_ISUPPORTS(StartupCacheDebugOutputStream, nsIObjectOutputStream,
nsIBinaryOutputStream, nsIOutputStream)
bool StartupCacheDebugOutputStream::CheckReferences(nsISupports* aObject) {
nsresult rv;
nsCOMPtr<nsIClassInfo> classInfo = do_QueryInterface(aObject);
if (!classInfo) {
NS_ERROR("aObject must implement nsIClassInfo");
return false;
}
uint32_t flags;
rv = classInfo->GetFlags(&flags);
NS_ENSURE_SUCCESS(rv, false);
if (flags & nsIClassInfo::SINGLETON) return true;
nsISupportsHashKey* key = mObjectMap->GetEntry(aObject);
if (key) {
NS_ERROR(
"non-singleton aObject is referenced multiple times in this"
"serialization, we don't support that.");
return false;
}
mObjectMap->PutEntry(aObject);
return true;
}
// nsIObjectOutputStream implementation
nsresult StartupCacheDebugOutputStream::WriteObject(nsISupports* aObject,
bool aIsStrongRef) {
nsCOMPtr<nsISupports> rootObject(do_QueryInterface(aObject));
NS_ASSERTION(rootObject.get() == aObject,
"bad call to WriteObject -- call WriteCompoundObject!");
bool check = CheckReferences(aObject);
NS_ENSURE_TRUE(check, NS_ERROR_FAILURE);
return mBinaryStream->WriteObject(aObject, aIsStrongRef);
}
nsresult StartupCacheDebugOutputStream::WriteSingleRefObject(
nsISupports* aObject) {
nsCOMPtr<nsISupports> rootObject(do_QueryInterface(aObject));
NS_ASSERTION(rootObject.get() == aObject,
"bad call to WriteSingleRefObject -- call WriteCompoundObject!");
bool check = CheckReferences(aObject);
NS_ENSURE_TRUE(check, NS_ERROR_FAILURE);
return mBinaryStream->WriteSingleRefObject(aObject);
}
nsresult StartupCacheDebugOutputStream::WriteCompoundObject(
nsISupports* aObject, const nsIID& aIID, bool aIsStrongRef) {
nsCOMPtr<nsISupports> rootObject(do_QueryInterface(aObject));
nsCOMPtr<nsISupports> roundtrip;
rootObject->QueryInterface(aIID, getter_AddRefs(roundtrip));
NS_ASSERTION(roundtrip.get() == aObject,
"bad aggregation or multiple inheritance detected by call to "
"WriteCompoundObject!");
bool check = CheckReferences(aObject);
NS_ENSURE_TRUE(check, NS_ERROR_FAILURE);
return mBinaryStream->WriteCompoundObject(aObject, aIID, aIsStrongRef);
}
nsresult StartupCacheDebugOutputStream::WriteID(nsID const& aID) {
return mBinaryStream->WriteID(aID);
}
char* StartupCacheDebugOutputStream::GetBuffer(uint32_t aLength,
uint32_t aAlignMask) {
return mBinaryStream->GetBuffer(aLength, aAlignMask);
}
void StartupCacheDebugOutputStream::PutBuffer(char* aBuffer, uint32_t aLength) {
mBinaryStream->PutBuffer(aBuffer, aLength);
}
#endif // DEBUG
} // namespace scache
} // namespace mozilla
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