Add dummy and LevelDB database backends

3 files changed, 636 insertions, 0 deletions

diff --git a/src/leveldb/helpers/memenv/memenv.cc b/src/leveldb/helpers/memenv/memenv.cc
new file mode 100644
index 000000000..5879de121
--- /dev/null
+++ b/src/leveldb/helpers/memenv/memenv.cc
@@ -0,0 +1,384 @@
+// 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 "helpers/memenv/memenv.h"
+
+#include "leveldb/env.h"
+#include "leveldb/status.h"
+#include "port/port.h"
+#include "util/mutexlock.h"
+#include <map>
+#include <string.h>
+#include <string>
+#include <vector>
+
+namespace leveldb {
+
+namespace {
+
+class FileState {
+ public:
+  // FileStates are reference counted. The initial reference count is zero
+  // and the caller must call Ref() at least once.
+  FileState() : refs_(0), size_(0) {}
+
+  // Increase the reference count.
+  void Ref() {
+    MutexLock lock(&refs_mutex_);
+    ++refs_;
+  }
+
+  // Decrease the reference count. Delete if this is the last reference.
+  void Unref() {
+    bool do_delete = false;
+
+    {
+      MutexLock lock(&refs_mutex_);
+      --refs_;
+      assert(refs_ >= 0);
+      if (refs_ <= 0) {
+        do_delete = true;
+      }
+    }
+
+    if (do_delete) {
+      delete this;
+    }
+  }
+
+  uint64_t Size() const { return size_; }
+
+  Status Read(uint64_t offset, size_t n, Slice* result, char* scratch) const {
+    if (offset > size_) {
+      return Status::IOError("Offset greater than file size.");
+    }
+    const uint64_t available = size_ - offset;
+    if (n > available) {
+      n = available;
+    }
+    if (n == 0) {
+      *result = Slice();
+      return Status::OK();
+    }
+
+    size_t block = offset / kBlockSize;
+    size_t block_offset = offset % kBlockSize;
+
+    if (n <= kBlockSize - block_offset) {
+      // The requested bytes are all in the first block.
+      *result = Slice(blocks_[block] + block_offset, n);
+      return Status::OK();
+    }
+
+    size_t bytes_to_copy = n;
+    char* dst = scratch;
+
+    while (bytes_to_copy > 0) {
+      size_t avail = kBlockSize - block_offset;
+      if (avail > bytes_to_copy) {
+        avail = bytes_to_copy;
+      }
+      memcpy(dst, blocks_[block] + block_offset, avail);
+
+      bytes_to_copy -= avail;
+      dst += avail;
+      block++;
+      block_offset = 0;
+    }
+
+    *result = Slice(scratch, n);
+    return Status::OK();
+  }
+
+  Status Append(const Slice& data) {
+    const char* src = data.data();
+    size_t src_len = data.size();
+
+    while (src_len > 0) {
+      size_t avail;
+      size_t offset = size_ % kBlockSize;
+
+      if (offset != 0) {
+        // There is some room in the last block.
+        avail = kBlockSize - offset;
+      } else {
+        // No room in the last block; push new one.
+        blocks_.push_back(new char[kBlockSize]);
+        avail = kBlockSize;
+      }
+
+      if (avail > src_len) {
+        avail = src_len;
+      }
+      memcpy(blocks_.back() + offset, src, avail);
+      src_len -= avail;
+      src += avail;
+      size_ += avail;
+    }
+
+    return Status::OK();
+  }
+
+ private:
+  // Private since only Unref() should be used to delete it.
+  ~FileState() {
+    for (std::vector<char*>::iterator i = blocks_.begin(); i != blocks_.end();
+         ++i) {
+      delete [] *i;
+    }
+  }
+
+  // No copying allowed.
+  FileState(const FileState&);
+  void operator=(const FileState&);
+
+  port::Mutex refs_mutex_;
+  int refs_;  // Protected by refs_mutex_;
+
+  // The following fields are not protected by any mutex. They are only mutable
+  // while the file is being written, and concurrent access is not allowed
+  // to writable files.
+  std::vector<char*> blocks_;
+  uint64_t size_;
+
+  enum { kBlockSize = 8 * 1024 };
+};
+
+class SequentialFileImpl : public SequentialFile {
+ public:
+  explicit SequentialFileImpl(FileState* file) : file_(file), pos_(0) {
+    file_->Ref();
+  }
+
+  ~SequentialFileImpl() {
+    file_->Unref();
+  }
+
+  virtual Status Read(size_t n, Slice* result, char* scratch) {
+    Status s = file_->Read(pos_, n, result, scratch);
+    if (s.ok()) {
+      pos_ += result->size();
+    }
+    return s;
+  }
+
+  virtual Status Skip(uint64_t n) {
+    if (pos_ > file_->Size()) {
+      return Status::IOError("pos_ > file_->Size()");
+    }
+    const size_t available = file_->Size() - pos_;
+    if (n > available) {
+      n = available;
+    }
+    pos_ += n;
+    return Status::OK();
+  }
+
+ private:
+  FileState* file_;
+  size_t pos_;
+};
+
+class RandomAccessFileImpl : public RandomAccessFile {
+ public:
+  explicit RandomAccessFileImpl(FileState* file) : file_(file) {
+    file_->Ref();
+  }
+
+  ~RandomAccessFileImpl() {
+    file_->Unref();
+  }
+
+  virtual Status Read(uint64_t offset, size_t n, Slice* result,
+                      char* scratch) const {
+    return file_->Read(offset, n, result, scratch);
+  }
+
+ private:
+  FileState* file_;
+};
+
+class WritableFileImpl : public WritableFile {
+ public:
+  WritableFileImpl(FileState* file) : file_(file) {
+    file_->Ref();
+  }
+
+  ~WritableFileImpl() {
+    file_->Unref();
+  }
+
+  virtual Status Append(const Slice& data) {
+    return file_->Append(data);
+  }
+
+  virtual Status Close() { return Status::OK(); }
+  virtual Status Flush() { return Status::OK(); }
+  virtual Status Sync() { return Status::OK(); }
+
+ private:
+  FileState* file_;
+};
+
+class NoOpLogger : public Logger {
+ public:
+  virtual void Logv(const char* format, va_list ap) { }
+};
+
+class InMemoryEnv : public EnvWrapper {
+ public:
+  explicit InMemoryEnv(Env* base_env) : EnvWrapper(base_env) { }
+
+  virtual ~InMemoryEnv() {
+    for (FileSystem::iterator i = file_map_.begin(); i != file_map_.end(); ++i){
+      i->second->Unref();
+    }
+  }
+
+  // Partial implementation of the Env interface.
+  virtual Status NewSequentialFile(const std::string& fname,
+                                   SequentialFile** result) {
+    MutexLock lock(&mutex_);
+    if (file_map_.find(fname) == file_map_.end()) {
+      *result = NULL;
+      return Status::IOError(fname, "File not found");
+    }
+
+    *result = new SequentialFileImpl(file_map_[fname]);
+    return Status::OK();
+  }
+
+  virtual Status NewRandomAccessFile(const std::string& fname,
+                                     RandomAccessFile** result) {
+    MutexLock lock(&mutex_);
+    if (file_map_.find(fname) == file_map_.end()) {
+      *result = NULL;
+      return Status::IOError(fname, "File not found");
+    }
+
+    *result = new RandomAccessFileImpl(file_map_[fname]);
+    return Status::OK();
+  }
+
+  virtual Status NewWritableFile(const std::string& fname,
+                                 WritableFile** result) {
+    MutexLock lock(&mutex_);
+    if (file_map_.find(fname) != file_map_.end()) {
+      DeleteFileInternal(fname);
+    }
+
+    FileState* file = new FileState();
+    file->Ref();
+    file_map_[fname] = file;
+
+    *result = new WritableFileImpl(file);
+    return Status::OK();
+  }
+
+  virtual bool FileExists(const std::string& fname) {
+    MutexLock lock(&mutex_);
+    return file_map_.find(fname) != file_map_.end();
+  }
+
+  virtual Status GetChildren(const std::string& dir,
+                             std::vector<std::string>* result) {
+    MutexLock lock(&mutex_);
+    result->clear();
+
+    for (FileSystem::iterator i = file_map_.begin(); i != file_map_.end(); ++i){
+      const std::string& filename = i->first;
+
+      if (filename.size() >= dir.size() + 1 && filename[dir.size()] == '/' &&
+          Slice(filename).starts_with(Slice(dir))) {
+        result->push_back(filename.substr(dir.size() + 1));
+      }
+    }
+
+    return Status::OK();
+  }
+
+  void DeleteFileInternal(const std::string& fname) {
+    if (file_map_.find(fname) == file_map_.end()) {
+      return;
+    }
+
+    file_map_[fname]->Unref();
+    file_map_.erase(fname);
+  }
+
+  virtual Status DeleteFile(const std::string& fname) {
+    MutexLock lock(&mutex_);
+    if (file_map_.find(fname) == file_map_.end()) {
+      return Status::IOError(fname, "File not found");
+    }
+
+    DeleteFileInternal(fname);
+    return Status::OK();
+  }
+
+  virtual Status CreateDir(const std::string& dirname) {
+    return Status::OK();
+  }
+
+  virtual Status DeleteDir(const std::string& dirname) {
+    return Status::OK();
+  }
+
+  virtual Status GetFileSize(const std::string& fname, uint64_t* file_size) {
+    MutexLock lock(&mutex_);
+    if (file_map_.find(fname) == file_map_.end()) {
+      return Status::IOError(fname, "File not found");
+    }
+
+    *file_size = file_map_[fname]->Size();
+    return Status::OK();
+  }
+
+  virtual Status RenameFile(const std::string& src,
+                            const std::string& target) {
+    MutexLock lock(&mutex_);
+    if (file_map_.find(src) == file_map_.end()) {
+      return Status::IOError(src, "File not found");
+    }
+
+    DeleteFileInternal(target);
+    file_map_[target] = file_map_[src];
+    file_map_.erase(src);
+    return Status::OK();
+  }
+
+  virtual Status LockFile(const std::string& fname, FileLock** lock) {
+    *lock = new FileLock;
+    return Status::OK();
+  }
+
+  virtual Status UnlockFile(FileLock* lock) {
+    delete lock;
+    return Status::OK();
+  }
+
+  virtual Status GetTestDirectory(std::string* path) {
+    *path = "/test";
+    return Status::OK();
+  }
+
+  virtual Status NewLogger(const std::string& fname, Logger** result) {
+    *result = new NoOpLogger;
+    return Status::OK();
+  }
+
+ private:
+  // Map from filenames to FileState objects, representing a simple file system.
+  typedef std::map<std::string, FileState*> FileSystem;
+  port::Mutex mutex_;
+  FileSystem file_map_;  // Protected by mutex_.
+};
+
+}  // namespace
+
+Env* NewMemEnv(Env* base_env) {
+  return new InMemoryEnv(base_env);
+}
+
+}  // namespace leveldb
diff --git a/src/leveldb/helpers/memenv/memenv.h b/src/leveldb/helpers/memenv/memenv.h
new file mode 100644
index 000000000..03b88de76
--- /dev/null
+++ b/src/leveldb/helpers/memenv/memenv.h
@@ -0,0 +1,20 @@
+// 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.
+
+#ifndef STORAGE_LEVELDB_HELPERS_MEMENV_MEMENV_H_
+#define STORAGE_LEVELDB_HELPERS_MEMENV_MEMENV_H_
+
+namespace leveldb {
+
+class Env;
+
+// Returns a new environment that stores its data in memory and delegates
+// all non-file-storage tasks to base_env. The caller must delete the result
+// when it is no longer needed.
+// *base_env must remain live while the result is in use.
+Env* NewMemEnv(Env* base_env);
+
+}  // namespace leveldb
+
+#endif  // STORAGE_LEVELDB_HELPERS_MEMENV_MEMENV_H_
diff --git a/src/leveldb/helpers/memenv/memenv_test.cc b/src/leveldb/helpers/memenv/memenv_test.cc
new file mode 100644
index 000000000..a44310fed
--- /dev/null
+++ b/src/leveldb/helpers/memenv/memenv_test.cc
@@ -0,0 +1,232 @@
+// 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 "helpers/memenv/memenv.h"
+
+#include "db/db_impl.h"
+#include "leveldb/db.h"
+#include "leveldb/env.h"
+#include "util/testharness.h"
+#include <string>
+#include <vector>
+
+namespace leveldb {
+
+class MemEnvTest {
+ public:
+  Env* env_;
+
+  MemEnvTest()
+      : env_(NewMemEnv(Env::Default())) {
+  }
+  ~MemEnvTest() {
+    delete env_;
+  }
+};
+
+TEST(MemEnvTest, Basics) {
+  uint64_t file_size;
+  WritableFile* writable_file;
+  std::vector<std::string> children;
+
+  ASSERT_OK(env_->CreateDir("/dir"));
+
+  // Check that the directory is empty.
+  ASSERT_TRUE(!env_->FileExists("/dir/non_existent"));
+  ASSERT_TRUE(!env_->GetFileSize("/dir/non_existent", &file_size).ok());
+  ASSERT_OK(env_->GetChildren("/dir", &children));
+  ASSERT_EQ(0, children.size());
+
+  // Create a file.
+  ASSERT_OK(env_->NewWritableFile("/dir/f", &writable_file));
+  delete writable_file;
+
+  // Check that the file exists.
+  ASSERT_TRUE(env_->FileExists("/dir/f"));
+  ASSERT_OK(env_->GetFileSize("/dir/f", &file_size));
+  ASSERT_EQ(0, file_size);
+  ASSERT_OK(env_->GetChildren("/dir", &children));
+  ASSERT_EQ(1, children.size());
+  ASSERT_EQ("f", children[0]);
+
+  // Write to the file.
+  ASSERT_OK(env_->NewWritableFile("/dir/f", &writable_file));
+  ASSERT_OK(writable_file->Append("abc"));
+  delete writable_file;
+
+  // Check for expected size.
+  ASSERT_OK(env_->GetFileSize("/dir/f", &file_size));
+  ASSERT_EQ(3, file_size);
+
+  // Check that renaming works.
+  ASSERT_TRUE(!env_->RenameFile("/dir/non_existent", "/dir/g").ok());
+  ASSERT_OK(env_->RenameFile("/dir/f", "/dir/g"));
+  ASSERT_TRUE(!env_->FileExists("/dir/f"));
+  ASSERT_TRUE(env_->FileExists("/dir/g"));
+  ASSERT_OK(env_->GetFileSize("/dir/g", &file_size));
+  ASSERT_EQ(3, file_size);
+
+  // Check that opening non-existent file fails.
+  SequentialFile* seq_file;
+  RandomAccessFile* rand_file;
+  ASSERT_TRUE(!env_->NewSequentialFile("/dir/non_existent", &seq_file).ok());
+  ASSERT_TRUE(!seq_file);
+  ASSERT_TRUE(!env_->NewRandomAccessFile("/dir/non_existent", &rand_file).ok());
+  ASSERT_TRUE(!rand_file);
+
+  // Check that deleting works.
+  ASSERT_TRUE(!env_->DeleteFile("/dir/non_existent").ok());
+  ASSERT_OK(env_->DeleteFile("/dir/g"));
+  ASSERT_TRUE(!env_->FileExists("/dir/g"));
+  ASSERT_OK(env_->GetChildren("/dir", &children));
+  ASSERT_EQ(0, children.size());
+  ASSERT_OK(env_->DeleteDir("/dir"));
+}
+
+TEST(MemEnvTest, ReadWrite) {
+  WritableFile* writable_file;
+  SequentialFile* seq_file;
+  RandomAccessFile* rand_file;
+  Slice result;
+  char scratch[100];
+
+  ASSERT_OK(env_->CreateDir("/dir"));
+
+  ASSERT_OK(env_->NewWritableFile("/dir/f", &writable_file));
+  ASSERT_OK(writable_file->Append("hello "));
+  ASSERT_OK(writable_file->Append("world"));
+  delete writable_file;
+
+  // Read sequentially.
+  ASSERT_OK(env_->NewSequentialFile("/dir/f", &seq_file));
+  ASSERT_OK(seq_file->Read(5, &result, scratch)); // Read "hello".
+  ASSERT_EQ(0, result.compare("hello"));
+  ASSERT_OK(seq_file->Skip(1));
+  ASSERT_OK(seq_file->Read(1000, &result, scratch)); // Read "world".
+  ASSERT_EQ(0, result.compare("world"));
+  ASSERT_OK(seq_file->Read(1000, &result, scratch)); // Try reading past EOF.
+  ASSERT_EQ(0, result.size());
+  ASSERT_OK(seq_file->Skip(100)); // Try to skip past end of file.
+  ASSERT_OK(seq_file->Read(1000, &result, scratch));
+  ASSERT_EQ(0, result.size());
+  delete seq_file;
+
+  // Random reads.
+  ASSERT_OK(env_->NewRandomAccessFile("/dir/f", &rand_file));
+  ASSERT_OK(rand_file->Read(6, 5, &result, scratch)); // Read "world".
+  ASSERT_EQ(0, result.compare("world"));
+  ASSERT_OK(rand_file->Read(0, 5, &result, scratch)); // Read "hello".
+  ASSERT_EQ(0, result.compare("hello"));
+  ASSERT_OK(rand_file->Read(10, 100, &result, scratch)); // Read "d".
+  ASSERT_EQ(0, result.compare("d"));
+
+  // Too high offset.
+  ASSERT_TRUE(!rand_file->Read(1000, 5, &result, scratch).ok());
+  delete rand_file;
+}
+
+TEST(MemEnvTest, Locks) {
+  FileLock* lock;
+
+  // These are no-ops, but we test they return success.
+  ASSERT_OK(env_->LockFile("some file", &lock));
+  ASSERT_OK(env_->UnlockFile(lock));
+}
+
+TEST(MemEnvTest, Misc) {
+  std::string test_dir;
+  ASSERT_OK(env_->GetTestDirectory(&test_dir));
+  ASSERT_TRUE(!test_dir.empty());
+
+  WritableFile* writable_file;
+  ASSERT_OK(env_->NewWritableFile("/a/b", &writable_file));
+
+  // These are no-ops, but we test they return success.
+  ASSERT_OK(writable_file->Sync());
+  ASSERT_OK(writable_file->Flush());
+  ASSERT_OK(writable_file->Close());
+  delete writable_file;
+}
+
+TEST(MemEnvTest, LargeWrite) {
+  const size_t kWriteSize = 300 * 1024;
+  char* scratch = new char[kWriteSize * 2];
+
+  std::string write_data;
+  for (size_t i = 0; i < kWriteSize; ++i) {
+    write_data.append(1, static_cast<char>(i));
+  }
+
+  WritableFile* writable_file;
+  ASSERT_OK(env_->NewWritableFile("/dir/f", &writable_file));
+  ASSERT_OK(writable_file->Append("foo"));
+  ASSERT_OK(writable_file->Append(write_data));
+  delete writable_file;
+
+  SequentialFile* seq_file;
+  Slice result;
+  ASSERT_OK(env_->NewSequentialFile("/dir/f", &seq_file));
+  ASSERT_OK(seq_file->Read(3, &result, scratch)); // Read "foo".
+  ASSERT_EQ(0, result.compare("foo"));
+
+  size_t read = 0;
+  std::string read_data;
+  while (read < kWriteSize) {
+    ASSERT_OK(seq_file->Read(kWriteSize - read, &result, scratch));
+    read_data.append(result.data(), result.size());
+    read += result.size();
+  }
+  ASSERT_TRUE(write_data == read_data);
+  delete seq_file;
+  delete [] scratch;
+}
+
+TEST(MemEnvTest, DBTest) {
+  Options options;
+  options.create_if_missing = true;
+  options.env = env_;
+  DB* db;
+
+  const Slice keys[] = {Slice("aaa"), Slice("bbb"), Slice("ccc")};
+  const Slice vals[] = {Slice("foo"), Slice("bar"), Slice("baz")};
+
+  ASSERT_OK(DB::Open(options, "/dir/db", &db));
+  for (size_t i = 0; i < 3; ++i) {
+    ASSERT_OK(db->Put(WriteOptions(), keys[i], vals[i]));
+  }
+
+  for (size_t i = 0; i < 3; ++i) {
+    std::string res;
+    ASSERT_OK(db->Get(ReadOptions(), keys[i], &res));
+    ASSERT_TRUE(res == vals[i]);
+  }
+
+  Iterator* iterator = db->NewIterator(ReadOptions());
+  iterator->SeekToFirst();
+  for (size_t i = 0; i < 3; ++i) {
+    ASSERT_TRUE(iterator->Valid());
+    ASSERT_TRUE(keys[i] == iterator->key());
+    ASSERT_TRUE(vals[i] == iterator->value());
+    iterator->Next();
+  }
+  ASSERT_TRUE(!iterator->Valid());
+  delete iterator;
+
+  DBImpl* dbi = reinterpret_cast<DBImpl*>(db);
+  ASSERT_OK(dbi->TEST_CompactMemTable());
+
+  for (size_t i = 0; i < 3; ++i) {
+    std::string res;
+    ASSERT_OK(db->Get(ReadOptions(), keys[i], &res));
+    ASSERT_TRUE(res == vals[i]);
+  }
+
+  delete db;
+}
+
+}  // namespace leveldb
+
+int main(int argc, char** argv) {
+  return leveldb::test::RunAllTests();
+}