/bitcoin/src/leveldb/helpers/memenv/memenv.cc

Source
// 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 <string.h>

#include <limits>
#include <map>
#include <string>
#include <vector>

#include "leveldb/env.h"
#include "leveldb/status.h"
#include "port/port.h"
#include "port/thread_annotations.h"
#include "util/mutexlock.h"

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) {}

  // No copying allowed.
  FileState(const FileState&) = delete;
  FileState& operator=(const FileState&) = delete;

  // 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 {
    MutexLock lock(&blocks_mutex_);
    return size_;
  }

  void Truncate() {
    MutexLock lock(&blocks_mutex_);
    for (char*& block : blocks_) {
      delete[] block;
    }
    blocks_.clear();
    size_ = 0;
  }

  Status Read(uint64_t offset, size_t n, Slice* result, char* scratch) const {
    MutexLock lock(&blocks_mutex_);
    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 <= std::numeric_limits<size_t>::max());
    size_t block = static_cast<size_t>(offset / kBlockSize);
    size_t block_offset = offset % kBlockSize;
    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();

    MutexLock lock(&blocks_mutex_);
    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:
  enum { kBlockSize = 8 * 1024 };

  // Private since only Unref() should be used to delete it.
  ~FileState() { Truncate(); }

  port::Mutex refs_mutex_;
  int refs_ GUARDED_BY(refs_mutex_);

  mutable port::Mutex blocks_mutex_;
  std::vector<char*> blocks_ GUARDED_BY(blocks_mutex_);
  uint64_t size_ GUARDED_BY(blocks_mutex_);
};

class SequentialFileImpl : public SequentialFile {
 public:
  explicit SequentialFileImpl(FileState* file) : file_(file), pos_(0) {
    file_->Ref();
  }

  ~SequentialFileImpl() override { file_->Unref(); }

  Status Read(size_t n, Slice* result, char* scratch) override {
    Status s = file_->Read(pos_, n, result, scratch);
    if (s.ok()) {
      pos_ += result->size();
    }
    return s;
  }

  Status Skip(uint64_t n) override {
    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();
  }

  virtual std::string GetName() const override { return "[memenv]"; }
 private:
  FileState* file_;
  uint64_t pos_;
};

class RandomAccessFileImpl : public RandomAccessFile {
 public:
  explicit RandomAccessFileImpl(FileState* file) : file_(file) { file_->Ref(); }

  ~RandomAccessFileImpl() override { file_->Unref(); }

  Status Read(uint64_t offset, size_t n, Slice* result,
              char* scratch) const override {
    return file_->Read(offset, n, result, scratch);
  }

  virtual std::string GetName() const override { return "[memenv]"; }
 private:
  FileState* file_;
};

class WritableFileImpl : public WritableFile {
 public:
  WritableFileImpl(FileState* file) : file_(file) { file_->Ref(); }

  ~WritableFileImpl() override { file_->Unref(); }

  Status Append(const Slice& data) override { return file_->Append(data); }

  Status Close() override { return Status::OK(); }
  Status Flush() override { return Status::OK(); }
  Status Sync() override { return Status::OK(); }

  virtual std::string GetName() const override { return "[memenv]"; }
 private:
  FileState* file_;
};

class NoOpLogger : public Logger {
 public:
  void Logv(const char* format, va_list ap) override {}
};

class InMemoryEnv : public EnvWrapper {
 public:
  explicit InMemoryEnv(Env* base_env) : EnvWrapper(base_env) {}

  ~InMemoryEnv() override {
    for (const auto& kvp : file_map_) {
      kvp.second->Unref();
    }
  }

  // Partial implementation of the Env interface.
  Status NewSequentialFile(const std::string& fname,
                           SequentialFile** result) override {
    MutexLock lock(&mutex_);
    if (file_map_.find(fname) == file_map_.end()) {
      *result = nullptr;
      return Status::IOError(fname, "File not found");
    }

    *result = new SequentialFileImpl(file_map_[fname]);
    return Status::OK();
  }

  Status NewRandomAccessFile(const std::string& fname,
                             RandomAccessFile** result) override {
    MutexLock lock(&mutex_);
    if (file_map_.find(fname) == file_map_.end()) {
      *result = nullptr;
      return Status::IOError(fname, "File not found");
    }

    *result = new RandomAccessFileImpl(file_map_[fname]);
    return Status::OK();
  }

  Status NewWritableFile(const std::string& fname,
                         WritableFile** result) override {
    MutexLock lock(&mutex_);
    FileSystem::iterator it = file_map_.find(fname);

    FileState* file;
    if (it == file_map_.end()) {
      // File is not currently open.
      file = new FileState();
      file->Ref();
      file_map_[fname] = file;
    } else {
      file = it->second;
      file->Truncate();
    }

    *result = new WritableFileImpl(file);
    return Status::OK();
  }

  Status NewAppendableFile(const std::string& fname,
                           WritableFile** result) override {
    MutexLock lock(&mutex_);
    FileState** sptr = &file_map_[fname];
    FileState* file = *sptr;
    if (file == nullptr) {
      file = new FileState();
      file->Ref();
    }
    *result = new WritableFileImpl(file);
    return Status::OK();
  }

  bool FileExists(const std::string& fname) override {
    MutexLock lock(&mutex_);
    return file_map_.find(fname) != file_map_.end();
  }

  Status GetChildren(const std::string& dir,
                     std::vector<std::string>* result) override {
    MutexLock lock(&mutex_);
    result->clear();

    for (const auto& kvp : file_map_) {
      const std::string& filename = kvp.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)
      EXCLUSIVE_LOCKS_REQUIRED(mutex_) {
    if (file_map_.find(fname) == file_map_.end()) {
      return;
    }

    file_map_[fname]->Unref();
    file_map_.erase(fname);
  }

  Status DeleteFile(const std::string& fname) override {
    MutexLock lock(&mutex_);
    if (file_map_.find(fname) == file_map_.end()) {
      return Status::IOError(fname, "File not found");
    }

    DeleteFileInternal(fname);
    return Status::OK();
  }

  Status CreateDir(const std::string& dirname) override { return Status::OK(); }

  Status DeleteDir(const std::string& dirname) override { return Status::OK(); }

  Status GetFileSize(const std::string& fname, uint64_t* file_size) override {
    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();
  }

  Status RenameFile(const std::string& src,
                    const std::string& target) override {
    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();
  }

  Status LockFile(const std::string& fname, FileLock** lock) override {
    *lock = new FileLock;
    return Status::OK();
  }

  Status UnlockFile(FileLock* lock) override {
    delete lock;
    return Status::OK();
  }

  Status GetTestDirectory(std::string* path) override {
    *path = "/test";
    return Status::OK();
  }

  Status NewLogger(const std::string& fname, Logger** result) override {
    *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_ GUARDED_BY(mutex_);
};

}  // namespace

Env* NewMemEnv(Env* base_env) { return new InMemoryEnv(base_env); }

}  // namespace leveldb

Coverage Report

Created: 2025-06-10 13:21

Line	Count	Source
1		// Copyright (c) 2011 The LevelDB Authors. All rights reserved.
2		// Use of this source code is governed by a BSD-style license that can be
3		// found in the LICENSE file. See the AUTHORS file for names of contributors.
4
5		#include "helpers/memenv/memenv.h"
6
7		#include <string.h>
8
9		#include <limits>
10		#include <map>
11		#include <string>
12		#include <vector>
13
14		#include "leveldb/env.h"
15		#include "leveldb/status.h"
16		#include "port/port.h"
17		#include "port/thread_annotations.h"
18		#include "util/mutexlock.h"
19
20		namespace leveldb {
21
22		namespace {
23
24		class FileState {
25		public:
26		// FileStates are reference counted. The initial reference count is zero
27		// and the caller must call Ref() at least once.
28	0	FileState() : refs_(0), size_(0) {}
29
30		// No copying allowed.
31		FileState(const FileState&) = delete;
32		FileState& operator=(const FileState&) = delete;
33
34		// Increase the reference count.
35	0	void Ref() {
36	0	MutexLock lock(&refs_mutex_);
37	0	++refs_;
38	0	}
39
40		// Decrease the reference count. Delete if this is the last reference.
41	0	void Unref() {
42	0	bool do_delete = false;
43
44	0	{
45	0	MutexLock lock(&refs_mutex_);
46	0	--refs_;
47	0	assert(refs_ >= 0); Branch (47:7): [True: 0, False: 0]
48	0	if (refs_ <= 0) { Branch (48:11): [True: 0, False: 0]
49	0	do_delete = true;
50	0	}
51	0	}
52
53	0	if (do_delete) { Branch (53:9): [True: 0, False: 0]
54	0	delete this;
55	0	}
56	0	}
57
58	0	uint64_t Size() const {
59	0	MutexLock lock(&blocks_mutex_);
60	0	return size_;
61	0	}
62
63	0	void Truncate() {
64	0	MutexLock lock(&blocks_mutex_);
65	0	for (char*& block : blocks_) { Branch (65:23): [True: 0, False: 0]
66	0	delete[] block;
67	0	}
68	0	blocks_.clear();
69	0	size_ = 0;
70	0	}
71
72	0	Status Read(uint64_t offset, size_t n, Slice* result, char* scratch) const {
73	0	MutexLock lock(&blocks_mutex_);
74	0	if (offset > size_) { Branch (74:9): [True: 0, False: 0]
75	0	return Status::IOError("Offset greater than file size.");
76	0	}
77	0	const uint64_t available = size_ - offset;
78	0	if (n > available) { Branch (78:9): [True: 0, False: 0]
79	0	n = static_cast<size_t>(available);
80	0	}
81	0	if (n == 0) { Branch (81:9): [True: 0, False: 0]
82	0	*result = Slice();
83	0	return Status::OK();
84	0	}
85
86	0	assert(offset / kBlockSize <= std::numeric_limits<size_t>::max()); Branch (86:5): [True: 0, False: 0]
87	0	size_t block = static_cast<size_t>(offset / kBlockSize);
88	0	size_t block_offset = offset % kBlockSize;
89	0	size_t bytes_to_copy = n;
90	0	char* dst = scratch;
91
92	0	while (bytes_to_copy > 0) { Branch (92:12): [True: 0, False: 0]
93	0	size_t avail = kBlockSize - block_offset;
94	0	if (avail > bytes_to_copy) { Branch (94:11): [True: 0, False: 0]
95	0	avail = bytes_to_copy;
96	0	}
97	0	memcpy(dst, blocks_[block] + block_offset, avail);
98
99	0	bytes_to_copy -= avail;
100	0	dst += avail;
101	0	block++;
102	0	block_offset = 0;
103	0	}
104
105	0	*result = Slice(scratch, n);
106	0	return Status::OK();
107	0	}
108
109	0	Status Append(const Slice& data) {
110	0	const char* src = data.data();
111	0	size_t src_len = data.size();
112
113	0	MutexLock lock(&blocks_mutex_);
114	0	while (src_len > 0) { Branch (114:12): [True: 0, False: 0]
115	0	size_t avail;
116	0	size_t offset = size_ % kBlockSize;
117
118	0	if (offset != 0) { Branch (118:11): [True: 0, False: 0]
119		// There is some room in the last block.
120	0	avail = kBlockSize - offset;
121	0	} else {
122		// No room in the last block; push new one.
123	0	blocks_.push_back(new char[kBlockSize]);
124	0	avail = kBlockSize;
125	0	}
126
127	0	if (avail > src_len) { Branch (127:11): [True: 0, False: 0]
128	0	avail = src_len;
129	0	}
130	0	memcpy(blocks_.back() + offset, src, avail);
131	0	src_len -= avail;
132	0	src += avail;
133	0	size_ += avail;
134	0	}
135
136	0	return Status::OK();
137	0	}
138
139		private:
140		enum { kBlockSize = 8 * 1024 };
141
142		// Private since only Unref() should be used to delete it.
143	0	~FileState() { Truncate(); }
144
145		port::Mutex refs_mutex_;
146		int refs_ GUARDED_BY(refs_mutex_);
147
148		mutable port::Mutex blocks_mutex_;
149		std::vector<char*> blocks_ GUARDED_BY(blocks_mutex_);
150		uint64_t size_ GUARDED_BY(blocks_mutex_);
151		};
152
153		class SequentialFileImpl : public SequentialFile {
154		public:
155	0	explicit SequentialFileImpl(FileState* file) : file_(file), pos_(0) {
156	0	file_->Ref();
157	0	}
158
159	0	~SequentialFileImpl() override { file_->Unref(); }
160
161	0	Status Read(size_t n, Slice* result, char* scratch) override {
162	0	Status s = file_->Read(pos_, n, result, scratch);
163	0	if (s.ok()) { Branch (163:9): [True: 0, False: 0]
164	0	pos_ += result->size();
165	0	}
166	0	return s;
167	0	}
168
169	0	Status Skip(uint64_t n) override {
170	0	if (pos_ > file_->Size()) { Branch (170:9): [True: 0, False: 0]
171	0	return Status::IOError("pos_ > file_->Size()");
172	0	}
173	0	const uint64_t available = file_->Size() - pos_;
174	0	if (n > available) { Branch (174:9): [True: 0, False: 0]
175	0	n = available;
176	0	}
177	0	pos_ += n;
178	0	return Status::OK();
179	0	}
180
181	0	virtual std::string GetName() const override { return "[memenv]"; }
182		private:
183		FileState* file_;
184		uint64_t pos_;
185		};
186
187		class RandomAccessFileImpl : public RandomAccessFile {
188		public:
189	0	explicit RandomAccessFileImpl(FileState* file) : file_(file) { file_->Ref(); }
190
191	0	~RandomAccessFileImpl() override { file_->Unref(); }
192
193		Status Read(uint64_t offset, size_t n, Slice* result,
194	0	char* scratch) const override {
195	0	return file_->Read(offset, n, result, scratch);
196	0	}
197
198	0	virtual std::string GetName() const override { return "[memenv]"; }
199		private:
200		FileState* file_;
201		};
202
203		class WritableFileImpl : public WritableFile {
204		public:
205	0	WritableFileImpl(FileState* file) : file_(file) { file_->Ref(); }
206
207	0	~WritableFileImpl() override { file_->Unref(); }
208
209	0	Status Append(const Slice& data) override { return file_->Append(data); }
210
211	0	Status Close() override { return Status::OK(); }
212	0	Status Flush() override { return Status::OK(); }
213	0	Status Sync() override { return Status::OK(); }
214
215	0	virtual std::string GetName() const override { return "[memenv]"; }
216		private:
217		FileState* file_;
218		};
219
220		class NoOpLogger : public Logger {
221		public:
222	0	void Logv(const char* format, va_list ap) override {}
223		};
224
225		class InMemoryEnv : public EnvWrapper {
226		public:
227	0	explicit InMemoryEnv(Env* base_env) : EnvWrapper(base_env) {}
228
229	0	~InMemoryEnv() override {
230	0	for (const auto& kvp : file_map_) { Branch (230:26): [True: 0, False: 0]
231	0	kvp.second->Unref();
232	0	}
233	0	}
234
235		// Partial implementation of the Env interface.
236		Status NewSequentialFile(const std::string& fname,
237	0	SequentialFile** result) override {
238	0	MutexLock lock(&mutex_);
239	0	if (file_map_.find(fname) == file_map_.end()) { Branch (239:9): [True: 0, False: 0]
240	0	*result = nullptr;
241	0	return Status::IOError(fname, "File not found");
242	0	}
243
244	0	*result = new SequentialFileImpl(file_map_[fname]);
245	0	return Status::OK();
246	0	}
247
248		Status NewRandomAccessFile(const std::string& fname,
249	0	RandomAccessFile** result) override {
250	0	MutexLock lock(&mutex_);
251	0	if (file_map_.find(fname) == file_map_.end()) { Branch (251:9): [True: 0, False: 0]
252	0	*result = nullptr;
253	0	return Status::IOError(fname, "File not found");
254	0	}
255
256	0	*result = new RandomAccessFileImpl(file_map_[fname]);
257	0	return Status::OK();
258	0	}
259
260		Status NewWritableFile(const std::string& fname,
261	0	WritableFile** result) override {
262	0	MutexLock lock(&mutex_);
263	0	FileSystem::iterator it = file_map_.find(fname);
264
265	0	FileState* file;
266	0	if (it == file_map_.end()) { Branch (266:9): [True: 0, False: 0]
267		// File is not currently open.
268	0	file = new FileState();
269	0	file->Ref();
270	0	file_map_[fname] = file;
271	0	} else {
272	0	file = it->second;
273	0	file->Truncate();
274	0	}
275
276	0	*result = new WritableFileImpl(file);
277	0	return Status::OK();
278	0	}
279
280		Status NewAppendableFile(const std::string& fname,
281	0	WritableFile** result) override {
282	0	MutexLock lock(&mutex_);
283	0	FileState** sptr = &file_map_[fname];
284	0	FileState* file = *sptr;
285	0	if (file == nullptr) { Branch (285:9): [True: 0, False: 0]
286	0	file = new FileState();
287	0	file->Ref();
288	0	}
289	0	*result = new WritableFileImpl(file);
290	0	return Status::OK();
291	0	}
292
293	0	bool FileExists(const std::string& fname) override {
294	0	MutexLock lock(&mutex_);
295	0	return file_map_.find(fname) != file_map_.end();
296	0	}
297
298		Status GetChildren(const std::string& dir,
299	0	std::vector<std::string>* result) override {
300	0	MutexLock lock(&mutex_);
301	0	result->clear();
302
303	0	for (const auto& kvp : file_map_) { Branch (303:26): [True: 0, False: 0]
304	0	const std::string& filename = kvp.first;
305
306	0	if (filename.size() >= dir.size() + 1 && filename[dir.size()] == '/' && Branch (306:11): [True: 0, False: 0] Branch (306:11): [True: 0, False: 0] Branch (306:48): [True: 0, False: 0]
307	0	Slice(filename).starts_with(Slice(dir))) { Branch (307:11): [True: 0, False: 0]
308	0	result->push_back(filename.substr(dir.size() + 1));
309	0	}
310	0	}
311
312	0	return Status::OK();
313	0	}
314
315		void DeleteFileInternal(const std::string& fname)
316	0	EXCLUSIVE_LOCKS_REQUIRED(mutex_) {
317	0	if (file_map_.find(fname) == file_map_.end()) { Branch (317:9): [True: 0, False: 0]
318	0	return;
319	0	}
320
321	0	file_map_[fname]->Unref();
322	0	file_map_.erase(fname);
323	0	}
324
325	0	Status DeleteFile(const std::string& fname) override {
326	0	MutexLock lock(&mutex_);
327	0	if (file_map_.find(fname) == file_map_.end()) { Branch (327:9): [True: 0, False: 0]
328	0	return Status::IOError(fname, "File not found");
329	0	}
330
331	0	DeleteFileInternal(fname);
332	0	return Status::OK();
333	0	}
334
335	0	Status CreateDir(const std::string& dirname) override { return Status::OK(); }
336
337	0	Status DeleteDir(const std::string& dirname) override { return Status::OK(); }
338
339	0	Status GetFileSize(const std::string& fname, uint64_t* file_size) override {
340	0	MutexLock lock(&mutex_);
341	0	if (file_map_.find(fname) == file_map_.end()) { Branch (341:9): [True: 0, False: 0]
342	0	return Status::IOError(fname, "File not found");
343	0	}
344
345	0	*file_size = file_map_[fname]->Size();
346	0	return Status::OK();
347	0	}
348
349		Status RenameFile(const std::string& src,
350	0	const std::string& target) override {
351	0	MutexLock lock(&mutex_);
352	0	if (file_map_.find(src) == file_map_.end()) { Branch (352:9): [True: 0, False: 0]
353	0	return Status::IOError(src, "File not found");
354	0	}
355
356	0	DeleteFileInternal(target);
357	0	file_map_[target] = file_map_[src];
358	0	file_map_.erase(src);
359	0	return Status::OK();
360	0	}
361
362	0	Status LockFile(const std::string& fname, FileLock** lock) override {
363	0	*lock = new FileLock;
364	0	return Status::OK();
365	0	}
366
367	0	Status UnlockFile(FileLock* lock) override {
368	0	delete lock;
369	0	return Status::OK();
370	0	}
371
372	0	Status GetTestDirectory(std::string* path) override {
373	0	*path = "/test";
374	0	return Status::OK();
375	0	}
376
377	0	Status NewLogger(const std::string& fname, Logger** result) override {
378	0	*result = new NoOpLogger;
379	0	return Status::OK();
380	0	}
381
382		private:
383		// Map from filenames to FileState objects, representing a simple file system.
384		typedef std::map<std::string, FileState*> FileSystem;
385
386		port::Mutex mutex_;
387		FileSystem file_map_ GUARDED_BY(mutex_);
388		};
389
390		} // namespace
391
392	0	Env* NewMemEnv(Env* base_env) { return new InMemoryEnv(base_env); }
393
394		} // namespace leveldb