| // 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 = static_cast<size_t>(available); |
| } |
| if (n == 0) { |
| *result = Slice(); |
| return Status::OK(); |
| } |
| |
| assert(offset / kBlockSize <= SIZE_MAX); |
| size_t block = static_cast<size_t>(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 uint64_t available = file_->Size() - pos_; |
| if (n > available) { |
| n = available; |
| } |
| pos_ += n; |
| return Status::OK(); |
| } |
| |
| private: |
| FileState* file_; |
| uint64_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 Status NewAppendableFile(const std::string& fname, |
| WritableFile** result) { |
| MutexLock lock(&mutex_); |
| FileState** sptr = &file_map_[fname]; |
| FileState* file = *sptr; |
| if (file == NULL) { |
| file = new FileState(); |
| file->Ref(); |
| } |
| *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 |