// Copyright (c) 2011 The LevelDB Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file. See the AUTHORS file for names of contributors.

#include "leveldb/env.h"

#include "port/port.h"
#include "util/testharness.h"
#include "util/testutil.h"

namespace leveldb {

static const int kDelayMicros = 100000;
static const int kReadOnlyFileLimit = 4;
static const int kMMapLimit = 4;

class EnvTest {
 private:
  port::Mutex mu_;
  std::string events_;

 public:
  Env* env_;
  EnvTest() : env_(Env::Default()) { }
};

static void SetBool(void* ptr) {
  reinterpret_cast<port::AtomicPointer*>(ptr)->NoBarrier_Store(ptr);
}


TEST(EnvTest, ReadWrite) {
  Random rnd(test::RandomSeed());

  // Get file to use for testing.
  std::string test_dir;
  ASSERT_OK(env_->GetTestDirectory(&test_dir));
  std::string test_file_name = test_dir + "/open_on_read.txt";
  WritableFile* wfile_tmp;
  ASSERT_OK(env_->NewWritableFile(test_file_name, &wfile_tmp));
  std::unique_ptr<WritableFile> wfile(wfile_tmp);

  // Fill a file with data generated via a sequence of randomly sized writes.
  static const size_t kDataSize = 10 * 1048576;
  std::string data;
  while (data.size() < kDataSize) {
    int len = rnd.Skewed(18);  // Up to 2^18 - 1, but typically much smaller
    std::string r;
    test::RandomString(&rnd, len, &r);
    ASSERT_OK(wfile->Append(r));
    data += r;
    if (rnd.OneIn(10)) {
      ASSERT_OK(wfile->Flush());
    }
  }
  ASSERT_OK(wfile->Sync());
  ASSERT_OK(wfile->Close());
  wfile.reset();

  // Read all data using a sequence of randomly sized reads.
  SequentialFile* rfile_tmp;
  ASSERT_OK(env_->NewSequentialFile(test_file_name, &rfile_tmp));
  std::unique_ptr<SequentialFile> rfile(rfile_tmp);
  std::string read_result;
  std::string scratch;
  while (read_result.size() < data.size()) {
    int len = std::min<int>(rnd.Skewed(18), data.size() - read_result.size());
    scratch.resize(std::max(len, 1));  // at least 1 so &scratch[0] is legal
    Slice read;
    ASSERT_OK(rfile->Read(len, &read, &scratch[0]));
    if (len > 0) {
      ASSERT_GT(read.size(), 0);
    }
    ASSERT_LE(read.size(), len);
    read_result.append(read.data(), read.size());
  }
  ASSERT_EQ(read_result, data);
}

TEST(EnvTest, RunImmediately) {
  port::AtomicPointer called (NULL);
  env_->Schedule(&SetBool, &called);
  env_->SleepForMicroseconds(kDelayMicros);
  ASSERT_TRUE(called.NoBarrier_Load() != NULL);
}

TEST(EnvTest, RunMany) {
  port::AtomicPointer last_id (NULL);

  struct CB {
    port::AtomicPointer* last_id_ptr;   // Pointer to shared slot
    uintptr_t id;             // Order# for the execution of this callback

    CB(port::AtomicPointer* p, int i) : last_id_ptr(p), id(i) { }

    static void Run(void* v) {
      CB* cb = reinterpret_cast<CB*>(v);
      void* cur = cb->last_id_ptr->NoBarrier_Load();
      ASSERT_EQ(cb->id-1, reinterpret_cast<uintptr_t>(cur));
      cb->last_id_ptr->Release_Store(reinterpret_cast<void*>(cb->id));
    }
  };

  // Schedule in different order than start time
  CB cb1(&last_id, 1);
  CB cb2(&last_id, 2);
  CB cb3(&last_id, 3);
  CB cb4(&last_id, 4);
  env_->Schedule(&CB::Run, &cb1);
  env_->Schedule(&CB::Run, &cb2);
  env_->Schedule(&CB::Run, &cb3);
  env_->Schedule(&CB::Run, &cb4);

  env_->SleepForMicroseconds(kDelayMicros);
  void* cur = last_id.Acquire_Load();
  ASSERT_EQ(4, reinterpret_cast<uintptr_t>(cur));
}

struct State {
  port::Mutex mu;
  int val;
  int num_running;
};

static void ThreadBody(void* arg) {
  State* s = reinterpret_cast<State*>(arg);
  s->mu.Lock();
  s->val += 1;
  s->num_running -= 1;
  s->mu.Unlock();
}

TEST(EnvTest, StartThread) {
  State state;
  state.val = 0;
  state.num_running = 3;
  for (int i = 0; i < 3; i++) {
    env_->StartThread(&ThreadBody, &state);
  }
  while (true) {
    state.mu.Lock();
    int num = state.num_running;
    state.mu.Unlock();
    if (num == 0) {
      break;
    }
    env_->SleepForMicroseconds(kDelayMicros);
  }
  ASSERT_EQ(state.val, 3);
}

TEST(EnvTest, TestOpenNonExistentFile) {
  // Write some test data to a single file that will be opened |n| times.
  std::string test_dir;
  ASSERT_OK(env_->GetTestDirectory(&test_dir));

  std::string non_existent_file = test_dir + "/non_existent_file";
  ASSERT_TRUE(!env_->FileExists(non_existent_file));

  RandomAccessFile* random_access_file;
  Status status = env_->NewRandomAccessFile(
      non_existent_file, &random_access_file);
  ASSERT_TRUE(status.IsNotFound());

  SequentialFile* sequential_file;
  status = env_->NewSequentialFile(non_existent_file, &sequential_file);
  ASSERT_TRUE(status.IsNotFound());
}

}  // namespace leveldb

int main(int argc, char** argv) {
  return leveldb::test::RunAllTests();
}