net/disk_cache/stress_cache.cc

// Copyright (c) 2010 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

// This is a simple application that stress-tests the crash recovery of the disk
// cache. The main application starts a copy of itself on a loop, checking the
// exit code of the child process. When the child dies in an unexpected way,
// the main application quits.

// The child application has two threads: one to exercise the cache in an
// infinite loop, and another one to asynchronously kill the process.

// A regular build should never crash.
// To test that the disk cache doesn't generate critical errors with regular
// application level crashes, add the following code and re-compile:
//
//     void BackendImpl::CriticalError(int error) {
//       NOTREACHED();
//
//     void BackendImpl::ReportError(int error) {
//       if (error && error != ERR_PREVIOUS_CRASH) {
//         NOTREACHED();
//       }

#include <string>
#include <vector>

#include "base/at_exit.h"
#include "base/command_line.h"
#include "base/debug/debugger.h"
#include "base/file_path.h"
#include "base/logging.h"
#include "base/message_loop.h"
#include "base/path_service.h"
#include "base/process_util.h"
#include "base/string_number_conversions.h"
#include "base/string_util.h"
#include "base/threading/platform_thread.h"
#include "base/threading/thread.h"
#include "base/utf_string_conversions.h"
#include "net/base/net_errors.h"
#include "net/base/test_completion_callback.h"
#include "net/base/io_buffer.h"
#include "net/disk_cache/backend_impl.h"
#include "net/disk_cache/disk_cache.h"
#include "net/disk_cache/disk_cache_test_util.h"

using base::Time;

const int kError = -1;
const int kExpectedCrash = 100;

// Starts a new process.
int RunSlave(int iteration) {
  FilePath exe;
  PathService::Get(base::FILE_EXE, &exe);

  CommandLine cmdline(exe);
  cmdline.AppendArg(base::IntToString(iteration));

  base::ProcessHandle handle;
  if (!base::LaunchApp(cmdline, false, false, &handle)) {
    printf("Unable to run test\n");
    return kError;
  }

  int exit_code;
  if (!base::WaitForExitCode(handle, &exit_code)) {
    printf("Unable to get return code\n");
    return kError;
  }
  return exit_code;
}

// Main loop for the master process.
int MasterCode() {
  for (int i = 0; i < 100000; i++) {
    int ret = RunSlave(i);
    if (kExpectedCrash != ret)
      return ret;
  }

  printf("More than enough...\n");

  return 0;
}

// -----------------------------------------------------------------------

// This thread will loop forever, adding and removing entries from the cache.
// iteration is the current crash cycle, so the entries on the cache are marked
// to know which instance of the application wrote them.
void StressTheCache(int iteration) {
  int cache_size = 0x800000;  // 8MB
  FilePath path = GetCacheFilePath().InsertBeforeExtensionASCII("_stress");

  base::Thread cache_thread("CacheThread");
  if (!cache_thread.StartWithOptions(
          base::Thread::Options(MessageLoop::TYPE_IO, 0)))
    return;

  TestCompletionCallback cb;
  disk_cache::Backend* cache;
  int rv = disk_cache::BackendImpl::CreateBackend(
               path, false, cache_size, net::DISK_CACHE,
               disk_cache::kNoLoadProtection | disk_cache::kNoRandom,
               cache_thread.message_loop_proxy(), NULL, &cache, &cb);

  if (cb.GetResult(rv) != net::OK) {
    printf("Unable to initialize cache.\n");
    return;
  }
  printf("Iteration %d, initial entries: %d\n", iteration,
         cache->GetEntryCount());

  int seed = static_cast<int>(Time::Now().ToInternalValue());
  srand(seed);

#ifdef NDEBUG
  const int kNumKeys = 5000;
#else
  const int kNumKeys = 1700;
#endif
  const int kNumEntries = 30;
  std::string keys[kNumKeys];
  disk_cache::Entry* entries[kNumEntries] = {0};

  for (int i = 0; i < kNumKeys; i++) {
    keys[i] = GenerateKey(true);
  }

  const int kSize = 4000;
  scoped_refptr<net::IOBuffer> buffer(new net::IOBuffer(kSize));
  memset(buffer->data(), 'k', kSize);

  for (int i = 0;; i++) {
    int slot = rand() % kNumEntries;
    int key = rand() % kNumKeys;
    bool truncate = rand() % 2 ? false : true;
    int size = kSize - (rand() % 4) * kSize / 4;

    if (entries[slot])
      entries[slot]->Close();

    rv = cache->OpenEntry(keys[key], &entries[slot], &cb);
    if (cb.GetResult(rv) != net::OK) {
      rv = cache->CreateEntry(keys[key], &entries[slot], &cb);
      CHECK_EQ(net::OK, cb.GetResult(rv));
    }

    base::snprintf(buffer->data(), kSize,
                   "i: %d iter: %d, size: %d, truncate: %d", i, iteration, size,
                   truncate ? 1 : 0);
    rv = entries[slot]->WriteData(0, 0, buffer, size, &cb, truncate);
    CHECK_EQ(size, cb.GetResult(rv));

    if (rand() % 100 > 80) {
      key = rand() % kNumKeys;
      rv = cache->DoomEntry(keys[key], &cb);
      cb.GetResult(rv);
    }

    if (!(i % 100))
      printf("Entries: %d    \r", i);
  }
}

// We want to prevent the timer thread from killing the process while we are
// waiting for the debugger to attach.
bool g_crashing = false;

class CrashTask : public Task {
 public:
  CrashTask() {}
  ~CrashTask() {}

  virtual void Run() {
    // Keep trying to run.
    RunSoon(MessageLoop::current());

    if (g_crashing)
      return;

    if (rand() % 100 > 1) {
      printf("sweet death...\n");
#if defined(OS_WIN)
      // Windows does more work on _exit() that we would like, so we use Kill.
      base::KillProcessById(base::GetCurrentProcId(), kExpectedCrash, false);
#elif defined(OS_POSIX)
      // On POSIX, _exit() will terminate the process with minimal cleanup,
      // and it is cleaner than killing.
      _exit(kExpectedCrash);
#endif
    }
  }

  static void RunSoon(MessageLoop* target_loop) {
    int task_delay = 10000;  // 10 seconds
    CrashTask* task = new CrashTask();
    target_loop->PostDelayedTask(FROM_HERE, task, task_delay);
  }
};

// We leak everything here :)
bool StartCrashThread() {
  base::Thread* thread = new base::Thread("party_crasher");
  if (!thread->Start())
    return false;

  CrashTask::RunSoon(thread->message_loop());
  return true;
}

void CrashHandler(const std::string& str) {
  g_crashing = true;
  base::debug::BreakDebugger();
}

// -----------------------------------------------------------------------

int main(int argc, const char* argv[]) {
  // Setup an AtExitManager so Singleton objects will be destructed.
  base::AtExitManager at_exit_manager;

  if (argc < 2)
    return MasterCode();

  logging::SetLogAssertHandler(CrashHandler);

  // Some time for the memory manager to flush stuff.
  base::PlatformThread::Sleep(3000);
  MessageLoop message_loop(MessageLoop::TYPE_IO);

  char* end;
  long int iteration = strtol(argv[1], &end, 0);

  if (!StartCrashThread()) {
    printf("failed to start thread\n");
    return kError;
  }

  StressTheCache(iteration);
  return 0;
}