StartupCache.cpp

/* -*- 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/MemoryReporting.h"
#include "mozilla/scache/StartupCache.h"

#include "nsAutoPtr.h"
#include "nsClassHashtable.h"
#include "nsComponentManagerUtils.h"
#include "nsDirectoryServiceUtils.h"
#include "nsIClassInfo.h"
#include "nsIFile.h"
#include "nsIObserver.h"
#include "nsIObserverService.h"
#include "nsIOutputStream.h"
#include "nsIStorageStream.h"
#include "nsIStreamBufferAccess.h"
#include "nsIStringStream.h"
#include "nsISupports.h"
#include "nsITimer.h"
#include "nsIZipWriter.h"
#include "nsIZipReader.h"
#include "nsWeakReference.h"
#include "nsZipArchive.h"
#include "mozilla/Omnijar.h"
#include "prenv.h"
#include "mozilla/Telemetry.h"
#include "nsThreadUtils.h"
#include "nsXULAppAPI.h"
#include "nsIProtocolHandler.h"
#include "GeckoProfiler.h"

#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

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,
    SizeOfMapping(),
    "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;
}

#define STARTUP_CACHE_NAME "startupCache." SC_WORDSIZE "." SC_ENDIAN

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;

NS_IMPL_ISUPPORTS(StartupCache, nsIMemoryReporter)

StartupCache::StartupCache()
  : mArchive(nullptr), mStartupWriteInitiated(false), mWriteThread(nullptr)
{ }

StartupCache::~StartupCache()
{
  if (mTimer) {
    mTimer->Cancel();
  }

  // Generally, the in-memory table should be empty here,
  // but an early shutdown means either mTimer didn't run
  // or the write thread is still running.
  WaitOnWriteThread();

  // If we shutdown quickly timer wont have fired. Instead of writing
  // it on the main thread and block the shutdown we simply wont update
  // the startup cache. Always do this if the file doesn't exist since
  // we use it part of the package step.
  if (!mArchive) {
    WriteToDisk();
  }

  UnregisterWeakMemoryReporter(this);
}

nsresult
StartupCache::Init()
{
  // workaround for bug 653936
  nsCOMPtr<nsIProtocolHandler> jarInitializer(do_GetService(NS_NETWORK_PROTOCOL_CONTRACTID_PREFIX "jar"));

  nsresult rv;

  // 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;
    }

    nsCOMPtr<nsIFile> profDir;
    NS_GetSpecialDirectory("ProfDS", getter_AddRefs(profDir));
    if (profDir) {
      bool same;
      if (NS_SUCCEEDED(profDir->Equals(file, &same)) && !same) {
        // We no longer store the startup cache in the main profile
        // directory, so we should cleanup the old one.
        if (NS_SUCCEEDED(
              profDir->AppendNative(NS_LITERAL_CSTRING("startupCache")))) {
          profDir->Remove(true);
        }
      }
    }

    rv = file->AppendNative(NS_LITERAL_CSTRING("startupCache"));
    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(NS_LITERAL_CSTRING(STARTUP_CACHE_NAME));

    NS_ENSURE_SUCCESS(rv, rv);

    mFile = do_QueryInterface(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 = LoadArchive();

  // 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);

  return NS_OK;
}

/**
 * LoadArchive can be called from the main thread or while reloading cache on write thread.
 */
nsresult
StartupCache::LoadArchive()
{
  if (gIgnoreDiskCache)
    return NS_ERROR_FAILURE;

  bool exists;
  mArchive = nullptr;
  nsresult rv = mFile->Exists(&exists);
  if (NS_FAILED(rv) || !exists)
    return NS_ERROR_FILE_NOT_FOUND;

  mArchive = new nsZipArchive();
  rv = mArchive->OpenArchive(mFile);
  return rv;
}

namespace {

nsresult
GetBufferFromZipArchive(nsZipArchive *zip, bool doCRC, const char* id,
                        UniquePtr<char[]>* outbuf, uint32_t* length)
{
  if (!zip)
    return NS_ERROR_NOT_AVAILABLE;

  nsZipItemPtr<char> zipItem(zip, id, doCRC);
  if (!zipItem)
    return NS_ERROR_NOT_AVAILABLE;

  *outbuf = zipItem.Forget();
  *length = zipItem.Length();
  return NS_OK;
}

} /* anonymous namespace */

// NOTE: this will not find a new entry until it has been written to disk!
// Consumer should take ownership of the resulting buffer.
nsresult
StartupCache::GetBuffer(const char* id, UniquePtr<char[]>* outbuf, uint32_t* length)
{
  AUTO_PROFILER_LABEL("StartupCache::GetBuffer", OTHER);

  NS_ASSERTION(NS_IsMainThread(), "Startup cache only available on main thread");

  WaitOnWriteThread();
  if (!mStartupWriteInitiated) {
    CacheEntry* entry;
    nsDependentCString idStr(id);
    mTable.Get(idStr, &entry);
    if (entry) {
      *outbuf = MakeUnique<char[]>(entry->size);
      memcpy(outbuf->get(), entry->data.get(), entry->size);
      *length = entry->size;
      return NS_OK;
    }
  }

  nsresult rv = GetBufferFromZipArchive(mArchive, true, id, outbuf, length);
  if (NS_SUCCEEDED(rv))
    return rv;

  RefPtr<nsZipArchive> omnijar = mozilla::Omnijar::GetReader(mozilla::Omnijar::APP);
  // no need to checksum omnijarred entries
  rv = GetBufferFromZipArchive(omnijar, false, id, outbuf, length);
  if (NS_SUCCEEDED(rv))
    return rv;

  omnijar = mozilla::Omnijar::GetReader(mozilla::Omnijar::GRE);
  // no need to checksum omnijarred entries
  return GetBufferFromZipArchive(omnijar, false, id, outbuf, length);
}

// Makes a copy of the buffer, client retains ownership of inbuf.
nsresult
StartupCache::PutBuffer(const char* id, const char* inbuf, uint32_t len)
{
  NS_ASSERTION(NS_IsMainThread(), "Startup cache only available on main thread");
  WaitOnWriteThread();
  if (StartupCache::gShutdownInitiated) {
    return NS_ERROR_NOT_AVAILABLE;
  }

  auto data = MakeUnique<char[]>(len);
  memcpy(data.get(), inbuf, len);

  nsCString idStr(id);
  // Cache it for now, we'll write all together later.
  CacheEntry* entry;

  if (mTable.Get(idStr)) {
    NS_WARNING("Existing entry in StartupCache.");
    // Double-caching is undesirable but not an error.
    return NS_OK;
  }

#ifdef DEBUG
  if (mArchive) {
    nsZipItem* zipItem = mArchive->GetItem(id);
    NS_ASSERTION(zipItem == nullptr, "Existing entry in disk StartupCache.");
  }
#endif

  entry = new CacheEntry(Move(data), len);
  mTable.Put(idStr, entry);
  mPendingWrites.AppendElement(idStr);
  return ResetStartupWriteTimer();
}

size_t
StartupCache::SizeOfMapping()
{
    return mArchive ? mArchive->SizeOfMapping() : 0;
}

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.ConstIter(); !iter.Done(); iter.Next()) {
        n += iter.Data()->SizeOfIncludingThis(aMallocSizeOf);
    }

    n += mPendingWrites.ShallowSizeOfExcludingThis(aMallocSizeOf);

    return n;
}

struct CacheWriteHolder
{
  nsCOMPtr<nsIZipWriter> writer;
  nsCOMPtr<nsIStringInputStream> stream;
  PRTime time;
};

static void
CacheCloseHelper(const nsACString& key, const CacheEntry* data,
                 const CacheWriteHolder* holder)
{
  MOZ_ASSERT(data); // assert key was found in mTable.

  nsresult rv;
  nsIStringInputStream* stream = holder->stream;
  nsIZipWriter* writer = holder->writer;

  stream->ShareData(data->data.get(), data->size);

#ifdef DEBUG
  bool hasEntry;
  rv = writer->HasEntry(key, &hasEntry);
  NS_ASSERTION(NS_SUCCEEDED(rv) && hasEntry == false,
               "Existing entry in disk StartupCache.");
#endif
  rv = writer->AddEntryStream(key, holder->time, true, stream, false);

  if (NS_FAILED(rv)) {
    NS_WARNING("cache entry deleted but not written to disk.");
  }
}


/**
 * WriteToDisk writes the cache out to disk. Callers of WriteToDisk need to call WaitOnWriteThread
 * to make sure there isn't a write happening on another thread
 */
void
StartupCache::WriteToDisk()
{
  nsresult rv;
  mStartupWriteInitiated = true;

  if (mTable.Count() == 0)
    return;

  nsCOMPtr<nsIZipWriter> zipW = do_CreateInstance("@mozilla.org/zipwriter;1");
  if (!zipW)
    return;

  rv = zipW->Open(mFile, PR_RDWR | PR_CREATE_FILE);
  if (NS_FAILED(rv)) {
    NS_WARNING("could not open zipfile for write");
    return;
  }

  // If we didn't have an mArchive member, that means that we failed to
  // open the startup cache for reading.  Therefore, we need to record
  // the time of creation in a zipfile comment; this has been useful for
  // Telemetry statistics.
  PRTime now = PR_Now();
  if (!mArchive) {
    nsCString comment;
    comment.Assign((char *)&now, sizeof(now));
    zipW->SetComment(comment);
  }

  nsCOMPtr<nsIStringInputStream> stream
    = do_CreateInstance("@mozilla.org/io/string-input-stream;1", &rv);
  if (NS_FAILED(rv)) {
    NS_WARNING("Couldn't create string input stream.");
    return;
  }

  CacheWriteHolder holder;
  holder.stream = stream;
  holder.writer = zipW;
  holder.time = now;

  for (auto& key : mPendingWrites) {
    CacheCloseHelper(key, mTable.Get(key), &holder);
  }
  mPendingWrites.Clear();
  mTable.Clear();

  // Close the archive so Windows doesn't choke.
  mArchive = nullptr;
  zipW->Close();

  // We succesfully wrote the archive to disk; mark the disk file as trusted
  gIgnoreDiskCache = false;

  // Our reader's view of the archive is outdated now, reload it.
  LoadArchive();
}

void
StartupCache::InvalidateCache()
{
  WaitOnWriteThread();
  mPendingWrites.Clear();
  mTable.Clear();
  mArchive = nullptr;
  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;
  LoadArchive();
}

void
StartupCache::IgnoreDiskCache()
{
  gIgnoreDiskCache = true;
  if (gStartupCache)
    gStartupCache->InvalidateCache();
}

/*
 * WaitOnWriteThread() is called from a main thread to wait for the worker
 * thread to finish. However since the same code is used in the worker thread and
 * main thread, the worker thread can also call WaitOnWriteThread() which is a no-op.
 */
void
StartupCache::WaitOnWriteThread()
{
  NS_ASSERTION(NS_IsMainThread(), "Startup cache should only wait for io thread on main thread");
  if (!mWriteThread || mWriteThread == PR_GetCurrentThread())
    return;

  PR_JoinThread(mWriteThread);
  mWriteThread = nullptr;
}

void
StartupCache::ThreadedWrite(void *aClosure)
{
  AUTO_PROFILER_REGISTER_THREAD("StartupCache");
  NS_SetCurrentThreadName("StartupCache");
  mozilla::IOInterposer::RegisterCurrentThread();
  /*
   * It is safe to use the pointer passed in aClosure to reference the
   * StartupCache object because the thread's lifetime is tightly coupled to
   * the lifetime of the StartupCache object; this thread is joined 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->WriteToDisk();
  mozilla::IOInterposer::UnregisterCurrentThread();
}

/*
 * The write-thread is spawned on a timeout(which is reset with every write). This
 * can avoid a slow shutdown. After writing out the cache, the zipreader is
 * reloaded on the worker thread.
 */
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->mWriteThread = PR_CreateThread(PR_USER_THREAD,
                                                  StartupCache::ThreadedWrite,
                                                  startupCacheObj,
                                                  PR_PRIORITY_NORMAL,
                                                  PR_GLOBAL_THREAD,
                                                  PR_JOINABLE_THREAD,
                                                  0);
}

// 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->WaitOnWriteThread();
    StartupCache::gShutdownInitiated = true;
  } else if (strcmp(topic, "startupcache-invalidate") == 0) {
    sc->InvalidateCache();
  }
  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::ResetStartupWriteTimer()
{
  mStartupWriteInitiated = false;
  nsresult rv = NS_OK;
  if (!mTimer)
    mTimer = NS_NewTimer();
  else
    rv = mTimer->Cancel();
  NS_ENSURE_SUCCESS(rv, rv);
  // Wait for 10 seconds, then write out the cache.
  mTimer->InitWithNamedFuncCallback(StartupCache::WriteTimeout, this, 60000,
                                    nsITimer::TYPE_ONE_SHOT,
                                    "StartupCache::WriteTimeout");
  return NS_OK;
}

bool
StartupCache::StartupWriteComplete()
{
  WaitOnWriteThread();
  return mStartupWriteInitiated && mTable.Count() == 0;
}

// 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