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Diffstat (limited to 'startupcache/StartupCache.cpp')
| -rw-r--r-- | startupcache/StartupCache.cpp | 956 |
1 files changed, 956 insertions, 0 deletions
diff --git a/startupcache/StartupCache.cpp b/startupcache/StartupCache.cpp new file mode 100644 index 0000000000..9c066a1951 --- /dev/null +++ b/startupcache/StartupCache.cpp @@ -0,0 +1,956 @@ +/* -*- 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 "mozilla/Try.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" +#ifdef MOZ_BACKGROUNDTASKS +# include "mozilla/BackgroundTasks.h" +#endif + +#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) { + MutexAutoLock lock(mTableLock); + 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() { +#ifdef MOZ_BACKGROUNDTASKS + if (BackgroundTasks::IsBackgroundTaskMode()) { + return nullptr; + } +#endif + + 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) {} + +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); + rv = mObserverService->AddObserver(mListener, "intl:app-locales-changed", + false); + NS_ENSURE_SUCCESS(rv, rv); + + { + MutexAutoLock lock(mTableLock); + 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::StartPrefetchMemory() { + { + MonitorAutoLock lock(mPrefetchComplete); + mPrefetchInProgress = true; + } + NS_DispatchBackgroundTask(NewRunnableMethod<uint8_t*, size_t>( + "StartupCache::ThreadedPrefetch", this, &StartupCache::ThreadedPrefetch, + mCacheData.get<uint8_t>().get(), mCacheData.size())); +} + +/** + * 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()) { + StartPrefetchMemory(); + } + + 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([&]() { + mTableLock.AssertCurrentThreadOwns(); + WaitOnPrefetch(); + 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"); + + MutexAutoLock lock(mTableLock); + return mTable.has(nsDependentCString(id)); +} + +nsresult StartupCache::GetBuffer(const char* id, const char** outbuf, + uint32_t* length) + MOZ_NO_THREAD_SAFETY_ANALYSIS { + 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); }); + + MutexAutoLock lock(mTableLock); + 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; + } + // It is 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. + // Also, WriteToDisk() requires mTableLock, so while it's writing we can't + // be here. + + size_t totalRead = 0; + size_t totalWritten = 0; + Span<const char> compressed = Span( + mCacheData.get<char>().get() + mCacheEntriesBaseOffset + value.mOffset, + value.mCompressedSize); + value.mData = UniqueFreePtr<char[]>(reinterpret_cast<char*>( + malloc(sizeof(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; + MutexAutoUnlock unlock(mTableLock); + 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, UniqueFreePtr<char[]>&& inbuf, + uint32_t len) MOZ_NO_THREAD_SAFETY_ANALYSIS { + NS_ASSERTION(NS_IsMainThread(), + "Startup cache only available on main thread"); + if (StartupCache::gShutdownInitiated) { + return NS_ERROR_NOT_AVAILABLE; + } + + // Try to gain the table write lock. If the background task to write the + // cache is running, this will fail. + MutexAutoTryLock lock(mTableLock); + if (!lock) { + return NS_ERROR_NOT_AVAILABLE; + } + mTableLock.AssertCurrentThreadOwns(); + 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; + } + + // 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. + * We own the mTableLock here. + */ +Result<Ok, nsresult> StartupCache::WriteToDisk() { + if (!mDirty || mWrittenOnce) { + return Ok(); + } + + if (!mFile) { + return Err(NS_ERROR_UNEXPECTED); + } + + AutoFDClose raiiFd; + MOZ_TRY(mFile->OpenNSPRFileDesc(PR_WRONLY | PR_CREATE_FILE | PR_TRUNCATE, + 0644, getter_Transfers(raiiFd))); + const auto fd = raiiFd.get(); + + nsTArray<StartupCacheEntry::KeyValuePair> entries(mTable.count()); + for (auto iter = mTable.iter(); !iter.done(); iter.next()) { + if (iter.get().value().mRequested) { + StartupCacheEntry::KeyValuePair kv(&iter.get().key(), + &iter.get().value()); + entries.AppendElement(kv); + } + } + + 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) { + WaitOnPrefetch(); + // Ensure we're not writing using mTable... + MutexAutoLock lock(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. If + // something knowingly invalidates the cache, the event can be counted with + // mAllowedInvalidationsCount. + MOZ_DIAGNOSTIC_ASSERT( + xpc::IsInAutomation() || + // The allowed invalidations can grow faster than the old tables, so + // guard against incorrect unsigned subtraction. + mAllowedInvalidationsCount > mOldTables.Length() || + // Now perform the real check. + mOldTables.Length() - mAllowedInvalidationsCount < 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_NOT_FOUND) { + gIgnoreDiskCache = true; + return; + } + } + gIgnoreDiskCache = false; + auto result = LoadArchive(); + if (NS_WARN_IF(result.isErr())) { + gIgnoreDiskCache = true; + } +} + +void StartupCache::CountAllowedInvalidation() { mAllowedInvalidationsCount++; } + +void StartupCache::MaybeInitShutdownWrite() { + if (mTimer) { + mTimer->Cancel(); + } + gShutdownInitiated = true; + + MaybeWriteOffMainThread(); +} + +void StartupCache::EnsureShutdownWriteComplete() { + MutexAutoLock lock(mTableLock); + // 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. + + // We got the lock. Keep the following in sync with + // MaybeWriteOffMainThread: + WaitOnPrefetch(); + 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. +} + +void StartupCache::IgnoreDiskCache() { + gIgnoreDiskCache = true; + if (gStartupCache) gStartupCache->InvalidateCache(); +} + +bool StartupCache::GetIgnoreDiskCache() { return gIgnoreDiskCache; } + +void StartupCache::WaitOnPrefetch() { + // This can't be called from within ThreadedPrefetch() + MonitorAutoLock lock(mPrefetchComplete); + while (mPrefetchInProgress) { + mPrefetchComplete.Wait(); + } +} + +void StartupCache::ThreadedPrefetch(uint8_t* aStart, size_t aSize) { + // Always notify of completion, even if MMAP_FAULT_HANDLER_CATCH() + // early-returns. + auto notifyPrefetchComplete = MakeScopeExit([&] { + MonitorAutoLock lock(mPrefetchComplete); + mPrefetchInProgress = false; + mPrefetchComplete.NotifyAll(); + }); + + // PrefetchMemory does madvise/equivalent, but doesn't access the memory + // pointed to by aStart + MMAP_FAULT_HANDLER_BEGIN_BUFFER(aStart, aSize) + PrefetchMemory(aStart, aSize); + MMAP_FAULT_HANDLER_CATCH() +} + +// mTableLock must be held +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() { + { + MutexAutoLock lock(mTableLock); + if (mWrittenOnce || (mCacheData.initialized() && !ShouldCompactCache())) { + return; + } + } + // Keep this code in sync with EnsureShutdownWriteComplete. + WaitOnPrefetch(); + { + MutexAutoLock lock(mTableLock); + mDirty = true; + mCacheData.reset(); + } + + RefPtr<StartupCache> self = this; + nsCOMPtr<nsIRunnable> runnable = + NS_NewRunnableFunction("StartupCache::Write", [self]() mutable { + MutexAutoLock lock(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->WaitOnPrefetch(); + 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); + } else if (strcmp(topic, "intl:app-locales-changed") == 0) { + // Live language switching invalidates the startup cache due to the history + // sidebar retaining localized strings in its internal SQL query. This + // should be a relatively rare event, but a user could do it an arbitrary + // number of times. + sc->CountAllowedInvalidation(); + } + 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; +} + +// For test code only +nsresult StartupCache::ResetStartupWriteTimerAndLock() { + MutexAutoLock lock(mTableLock); + return ResetStartupWriteTimer(); +} + +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; + MutexAutoLock lock(mTableLock); + 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; + + bool inserted = mObjectMap->EnsureInserted(aObject); + if (!inserted) { + NS_ERROR( + "non-singleton aObject is referenced multiple times in this" + "serialization, we don't support that."); + } + + return inserted; +} + +// 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 |