/bitcoin/src/leveldb/table/table.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 "leveldb/table.h"

#include "leveldb/cache.h"
#include "leveldb/comparator.h"
#include "leveldb/env.h"
#include "leveldb/filter_policy.h"
#include "leveldb/options.h"
#include "table/block.h"
#include "table/filter_block.h"
#include "table/format.h"
#include "table/two_level_iterator.h"
#include "util/coding.h"

namespace leveldb {

struct Table::Rep {
  ~Rep() {
    delete filter;
    delete[] filter_data;
    delete index_block;
  }

  Options options;
  Status status;
  RandomAccessFile* file;
  uint64_t cache_id;
  FilterBlockReader* filter;
  const char* filter_data;

  BlockHandle metaindex_handle;  // Handle to metaindex_block: saved from footer
  Block* index_block;
};

Status Table::Open(const Options& options, RandomAccessFile* file,
                   uint64_t size, Table** table) {
  *table = nullptr;
  if (size < Footer::kEncodedLength) {
    return Status::Corruption("file is too short to be an sstable");
  }

  char footer_space[Footer::kEncodedLength];
  Slice footer_input;
  Status s = file->Read(size - Footer::kEncodedLength, Footer::kEncodedLength,
                        &footer_input, footer_space);
  if (!s.ok()) return s;

  Footer footer;
  s = footer.DecodeFrom(&footer_input);
  if (!s.ok()) return s;

  // Read the index block
  BlockContents index_block_contents;
  if (s.ok()) {
    ReadOptions opt;
    if (options.paranoid_checks) {
      opt.verify_checksums = true;
    }
    s = ReadBlock(file, opt, footer.index_handle(), &index_block_contents);
  }

  if (s.ok()) {
    // We've successfully read the footer and the index block: we're
    // ready to serve requests.
    Block* index_block = new Block(index_block_contents);
    Rep* rep = new Table::Rep;
    rep->options = options;
    rep->file = file;
    rep->metaindex_handle = footer.metaindex_handle();
    rep->index_block = index_block;
    rep->cache_id = (options.block_cache ? options.block_cache->NewId() : 0);
    rep->filter_data = nullptr;
    rep->filter = nullptr;
    *table = new Table(rep);
    (*table)->ReadMeta(footer);
  }

  return s;
}

void Table::ReadMeta(const Footer& footer) {
  if (rep_->options.filter_policy == nullptr) {
    return;  // Do not need any metadata
  }

  // TODO(sanjay): Skip this if footer.metaindex_handle() size indicates
  // it is an empty block.
  ReadOptions opt;
  if (rep_->options.paranoid_checks) {
    opt.verify_checksums = true;
  }
  BlockContents contents;
  if (!ReadBlock(rep_->file, opt, footer.metaindex_handle(), &contents).ok()) {
    // Do not propagate errors since meta info is not needed for operation
    return;
  }
  Block* meta = new Block(contents);

  Iterator* iter = meta->NewIterator(BytewiseComparator());
  std::string key = "filter.";
  key.append(rep_->options.filter_policy->Name());
  iter->Seek(key);
  if (iter->Valid() && iter->key() == Slice(key)) {
    ReadFilter(iter->value());
  }
  delete iter;
  delete meta;
}

void Table::ReadFilter(const Slice& filter_handle_value) {
  Slice v = filter_handle_value;
  BlockHandle filter_handle;
  if (!filter_handle.DecodeFrom(&v).ok()) {
    return;
  }

  // We might want to unify with ReadBlock() if we start
  // requiring checksum verification in Table::Open.
  ReadOptions opt;
  if (rep_->options.paranoid_checks) {
    opt.verify_checksums = true;
  }
  BlockContents block;
  if (!ReadBlock(rep_->file, opt, filter_handle, &block).ok()) {
    return;
  }
  if (block.heap_allocated) {
    rep_->filter_data = block.data.data();  // Will need to delete later
  }
  rep_->filter = new FilterBlockReader(rep_->options.filter_policy, block.data);
}

Table::~Table() { delete rep_; }

static void DeleteBlock(void* arg, void* ignored) {
  delete reinterpret_cast<Block*>(arg);
}

static void DeleteCachedBlock(const Slice& key, void* value) {
  Block* block = reinterpret_cast<Block*>(value);
  delete block;
}

static void ReleaseBlock(void* arg, void* h) {
  Cache* cache = reinterpret_cast<Cache*>(arg);
  Cache::Handle* handle = reinterpret_cast<Cache::Handle*>(h);
  cache->Release(handle);
}

// Convert an index iterator value (i.e., an encoded BlockHandle)
// into an iterator over the contents of the corresponding block.
Iterator* Table::BlockReader(void* arg, const ReadOptions& options,
                             const Slice& index_value) {
  Table* table = reinterpret_cast<Table*>(arg);
  Cache* block_cache = table->rep_->options.block_cache;
  Block* block = nullptr;
  Cache::Handle* cache_handle = nullptr;

  BlockHandle handle;
  Slice input = index_value;
  Status s = handle.DecodeFrom(&input);
  // We intentionally allow extra stuff in index_value so that we
  // can add more features in the future.

  if (s.ok()) {
    BlockContents contents;
    if (block_cache != nullptr) {
      char cache_key_buffer[16];
      EncodeFixed64(cache_key_buffer, table->rep_->cache_id);
      EncodeFixed64(cache_key_buffer + 8, handle.offset());
      Slice key(cache_key_buffer, sizeof(cache_key_buffer));
      cache_handle = block_cache->Lookup(key);
      if (cache_handle != nullptr) {
        block = reinterpret_cast<Block*>(block_cache->Value(cache_handle));
      } else {
        s = ReadBlock(table->rep_->file, options, handle, &contents);
        if (s.ok()) {
          block = new Block(contents);
          if (contents.cachable && options.fill_cache) {
            cache_handle = block_cache->Insert(key, block, block->size(),
                                               &DeleteCachedBlock);
          }
        }
      }
    } else {
      s = ReadBlock(table->rep_->file, options, handle, &contents);
      if (s.ok()) {
        block = new Block(contents);
      }
    }
  }

  Iterator* iter;
  if (block != nullptr) {
    iter = block->NewIterator(table->rep_->options.comparator);
    if (cache_handle == nullptr) {
      iter->RegisterCleanup(&DeleteBlock, block, nullptr);
    } else {
      iter->RegisterCleanup(&ReleaseBlock, block_cache, cache_handle);
    }
  } else {
    iter = NewErrorIterator(s);
  }
  return iter;
}

Iterator* Table::NewIterator(const ReadOptions& options) const {
  return NewTwoLevelIterator(
      rep_->index_block->NewIterator(rep_->options.comparator),
      &Table::BlockReader, const_cast<Table*>(this), options);
}

Status Table::InternalGet(const ReadOptions& options, const Slice& k, void* arg,
                          void (*handle_result)(void*, const Slice&,
                                                const Slice&)) {
  Status s;
  Iterator* iiter = rep_->index_block->NewIterator(rep_->options.comparator);
  iiter->Seek(k);
  if (iiter->Valid()) {
    Slice handle_value = iiter->value();
    FilterBlockReader* filter = rep_->filter;
    BlockHandle handle;
    if (filter != nullptr && handle.DecodeFrom(&handle_value).ok() &&
        !filter->KeyMayMatch(handle.offset(), k)) {
      // Not found
    } else {
      Iterator* block_iter = BlockReader(this, options, iiter->value());
      block_iter->Seek(k);
      if (block_iter->Valid()) {
        (*handle_result)(arg, block_iter->key(), block_iter->value());
      }
      s = block_iter->status();
      delete block_iter;
    }
  }
  if (s.ok()) {
    s = iiter->status();
  }
  delete iiter;
  return s;
}

uint64_t Table::ApproximateOffsetOf(const Slice& key) const {
  Iterator* index_iter =
      rep_->index_block->NewIterator(rep_->options.comparator);
  index_iter->Seek(key);
  uint64_t result;
  if (index_iter->Valid()) {
    BlockHandle handle;
    Slice input = index_iter->value();
    Status s = handle.DecodeFrom(&input);
    if (s.ok()) {
      result = handle.offset();
    } else {
      // Strange: we can't decode the block handle in the index block.
      // We'll just return the offset of the metaindex block, which is
      // close to the whole file size for this case.
      result = rep_->metaindex_handle.offset();
    }
  } else {
    // key is past the last key in the file.  Approximate the offset
    // by returning the offset of the metaindex block (which is
    // right near the end of the file).
    result = rep_->metaindex_handle.offset();
  }
  delete index_iter;
  return result;
}

}  // 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 "leveldb/table.h"
6
7		#include "leveldb/cache.h"
8		#include "leveldb/comparator.h"
9		#include "leveldb/env.h"
10		#include "leveldb/filter_policy.h"
11		#include "leveldb/options.h"
12		#include "table/block.h"
13		#include "table/filter_block.h"
14		#include "table/format.h"
15		#include "table/two_level_iterator.h"
16		#include "util/coding.h"
17
18		namespace leveldb {
19
20		struct Table::Rep {
21	24	~Rep() {
22	24	delete filter;
23	24	delete[] filter_data;
24	24	delete index_block;
25	24	}
26
27		Options options;
28		Status status;
29		RandomAccessFile* file;
30		uint64_t cache_id;
31		FilterBlockReader* filter;
32		const char* filter_data;
33
34		BlockHandle metaindex_handle; // Handle to metaindex_block: saved from footer
35		Block* index_block;
36		};
37
38		Status Table::Open(const Options& options, RandomAccessFile* file,
39	24	uint64_t size, Table** table) {
40	24	*table = nullptr;
41	24	if (size < Footer::kEncodedLength) { Branch (41:7): [True: 0, False: 24]
42	0	return Status::Corruption("file is too short to be an sstable");
43	0	}
44
45	24	char footer_space[Footer::kEncodedLength];
46	24	Slice footer_input;
47	24	Status s = file->Read(size - Footer::kEncodedLength, Footer::kEncodedLength,
48	24	&footer_input, footer_space);
49	24	if (!s.ok()) return s; Branch (49:7): [True: 0, False: 24]
50
51	24	Footer footer;
52	24	s = footer.DecodeFrom(&footer_input);
53	24	if (!s.ok()) return s; Branch (53:7): [True: 0, False: 24]
54
55		// Read the index block
56	24	BlockContents index_block_contents;
57	24	if (s.ok()) { Branch (57:7): [True: 24, False: 0]
58	24	ReadOptions opt;
59	24	if (options.paranoid_checks) { Branch (59:9): [True: 24, False: 0]
60	24	opt.verify_checksums = true;
61	24	}
62	24	s = ReadBlock(file, opt, footer.index_handle(), &index_block_contents);
63	24	}
64
65	24	if (s.ok()) { Branch (65:7): [True: 24, False: 0]
66		// We've successfully read the footer and the index block: we're
67		// ready to serve requests.
68	24	Block* index_block = new Block(index_block_contents);
69	24	Rep* rep = new Table::Rep;
70	24	rep->options = options;
71	24	rep->file = file;
72	24	rep->metaindex_handle = footer.metaindex_handle();
73	24	rep->index_block = index_block;
74	24	rep->cache_id = (options.block_cache ? options.block_cache->NewId() : 0); Branch (74:22): [True: 24, False: 0]
75	24	rep->filter_data = nullptr;
76	24	rep->filter = nullptr;
77	24	*table = new Table(rep);
78	24	(*table)->ReadMeta(footer);
79	24	}
80
81	24	return s;
82	24	}
83
84	24	void Table::ReadMeta(const Footer& footer) {
85	24	if (rep_->options.filter_policy == nullptr) { Branch (85:7): [True: 0, False: 24]
86	0	return; // Do not need any metadata
87	0	}
88
89		// TODO(sanjay): Skip this if footer.metaindex_handle() size indicates
90		// it is an empty block.
91	24	ReadOptions opt;
92	24	if (rep_->options.paranoid_checks) { Branch (92:7): [True: 24, False: 0]
93	24	opt.verify_checksums = true;
94	24	}
95	24	BlockContents contents;
96	24	if (!ReadBlock(rep_->file, opt, footer.metaindex_handle(), &contents).ok()) { Branch (96:7): [True: 0, False: 24]
97		// Do not propagate errors since meta info is not needed for operation
98	0	return;
99	0	}
100	24	Block* meta = new Block(contents);
101
102	24	Iterator* iter = meta->NewIterator(BytewiseComparator());
103	24	std::string key = "filter.";
104	24	key.append(rep_->options.filter_policy->Name());
105	24	iter->Seek(key);
106	24	if (iter->Valid() && iter->key() == Slice(key)) { Branch (106:7): [True: 24, False: 0] Branch (106:7): [True: 24, False: 0] Branch (106:24): [True: 24, False: 0]
107	24	ReadFilter(iter->value());
108	24	}
109	24	delete iter;
110	24	delete meta;
111	24	}
112
113	24	void Table::ReadFilter(const Slice& filter_handle_value) {
114	24	Slice v = filter_handle_value;
115	24	BlockHandle filter_handle;
116	24	if (!filter_handle.DecodeFrom(&v).ok()) { Branch (116:7): [True: 0, False: 24]
117	0	return;
118	0	}
119
120		// We might want to unify with ReadBlock() if we start
121		// requiring checksum verification in Table::Open.
122	24	ReadOptions opt;
123	24	if (rep_->options.paranoid_checks) { Branch (123:7): [True: 24, False: 0]
124	24	opt.verify_checksums = true;
125	24	}
126	24	BlockContents block;
127	24	if (!ReadBlock(rep_->file, opt, filter_handle, &block).ok()) { Branch (127:7): [True: 0, False: 24]
128	0	return;
129	0	}
130	24	if (block.heap_allocated) { Branch (130:7): [True: 0, False: 24]
131	0	rep_->filter_data = block.data.data(); // Will need to delete later
132	0	}
133	24	rep_->filter = new FilterBlockReader(rep_->options.filter_policy, block.data);
134	24	}
135
136	24	Table::~Table() { delete rep_; }
137
138	12	static void DeleteBlock(void* arg, void* ignored) {
139	12	delete reinterpret_cast<Block*>(arg);
140	12	}
141
142	0	static void DeleteCachedBlock(const Slice& key, void* value) {
143	0	Block* block = reinterpret_cast<Block*>(value);
144	0	delete block;
145	0	}
146
147	0	static void ReleaseBlock(void* arg, void* h) {
148	0	Cache* cache = reinterpret_cast<Cache*>(arg);
149	0	Cache::Handle* handle = reinterpret_cast<Cache::Handle*>(h);
150	0	cache->Release(handle);
151	0	}
152
153		// Convert an index iterator value (i.e., an encoded BlockHandle)
154		// into an iterator over the contents of the corresponding block.
155		Iterator* Table::BlockReader(void* arg, const ReadOptions& options,
156	12	const Slice& index_value) {
157	12	Table* table = reinterpret_cast<Table*>(arg);
158	12	Cache* block_cache = table->rep_->options.block_cache;
159	12	Block* block = nullptr;
160	12	Cache::Handle* cache_handle = nullptr;
161
162	12	BlockHandle handle;
163	12	Slice input = index_value;
164	12	Status s = handle.DecodeFrom(&input);
165		// We intentionally allow extra stuff in index_value so that we
166		// can add more features in the future.
167
168	12	if (s.ok()) { Branch (168:7): [True: 12, False: 0]
169	12	BlockContents contents;
170	12	if (block_cache != nullptr) { Branch (170:9): [True: 12, False: 0]
171	12	char cache_key_buffer[16];
172	12	EncodeFixed64(cache_key_buffer, table->rep_->cache_id);
173	12	EncodeFixed64(cache_key_buffer + 8, handle.offset());
174	12	Slice key(cache_key_buffer, sizeof(cache_key_buffer));
175	12	cache_handle = block_cache->Lookup(key);
176	12	if (cache_handle != nullptr) { Branch (176:11): [True: 0, False: 12]
177	0	block = reinterpret_cast<Block*>(block_cache->Value(cache_handle));
178	12	} else {
179	12	s = ReadBlock(table->rep_->file, options, handle, &contents);
180	12	if (s.ok()) { Branch (180:13): [True: 12, False: 0]
181	12	block = new Block(contents);
182	12	if (contents.cachable && options.fill_cache) { Branch (182:15): [True: 0, False: 12] Branch (182:36): [True: 0, False: 0]
183	0	cache_handle = block_cache->Insert(key, block, block->size(),
184	0	&DeleteCachedBlock);
185	0	}
186	12	}
187	12	}
188	12	} else {
189	0	s = ReadBlock(table->rep_->file, options, handle, &contents);
190	0	if (s.ok()) { Branch (190:11): [True: 0, False: 0]
191	0	block = new Block(contents);
192	0	}
193	0	}
194	12	}
195
196	12	Iterator* iter;
197	12	if (block != nullptr) { Branch (197:7): [True: 12, False: 0]
198	12	iter = block->NewIterator(table->rep_->options.comparator);
199	12	if (cache_handle == nullptr) { Branch (199:9): [True: 12, False: 0]
200	12	iter->RegisterCleanup(&DeleteBlock, block, nullptr);
201	12	} else {
202	0	iter->RegisterCleanup(&ReleaseBlock, block_cache, cache_handle);
203	0	}
204	12	} else {
205	0	iter = NewErrorIterator(s);
206	0	}
207	12	return iter;
208	12	}
209
210	31	Iterator* Table::NewIterator(const ReadOptions& options) const {
211	31	return NewTwoLevelIterator(
212	31	rep_->index_block->NewIterator(rep_->options.comparator),
213	31	&Table::BlockReader, const_cast<Table*>(this), options);
214	31	}
215
216		Status Table::InternalGet(const ReadOptions& options, const Slice& k, void* arg,
217		void (handle_result)(void, const Slice&,
218	5	const Slice&)) {
219	5	Status s;
220	5	Iterator* iiter = rep_->index_block->NewIterator(rep_->options.comparator);
221	5	iiter->Seek(k);
222	5	if (iiter->Valid()) { Branch (222:7): [True: 5, False: 0]
223	5	Slice handle_value = iiter->value();
224	5	FilterBlockReader* filter = rep_->filter;
225	5	BlockHandle handle;
226	5	if (filter != nullptr && handle.DecodeFrom(&handle_value).ok() && Branch (226:9): [True: 5, False: 0] Branch (226:9): [True: 0, False: 5] Branch (226:30): [True: 5, False: 0]
227	5	!filter->KeyMayMatch(handle.offset(), k)) { Branch (227:9): [True: 0, False: 5]
228		// Not found
229	5	} else {
230	5	Iterator* block_iter = BlockReader(this, options, iiter->value());
231	5	block_iter->Seek(k);
232	5	if (block_iter->Valid()) { Branch (232:11): [True: 5, False: 0]
233	5	(*handle_result)(arg, block_iter->key(), block_iter->value());
234	5	}
235	5	s = block_iter->status();
236	5	delete block_iter;
237	5	}
238	5	}
239	5	if (s.ok()) { Branch (239:7): [True: 5, False: 0]
240	5	s = iiter->status();
241	5	}
242	5	delete iiter;
243	5	return s;
244	5	}
245
246	0	uint64_t Table::ApproximateOffsetOf(const Slice& key) const {
247	0	Iterator* index_iter =
248	0	rep_->index_block->NewIterator(rep_->options.comparator);
249	0	index_iter->Seek(key);
250	0	uint64_t result;
251	0	if (index_iter->Valid()) { Branch (251:7): [True: 0, False: 0]
252	0	BlockHandle handle;
253	0	Slice input = index_iter->value();
254	0	Status s = handle.DecodeFrom(&input);
255	0	if (s.ok()) { Branch (255:9): [True: 0, False: 0]
256	0	result = handle.offset();
257	0	} else {
258		// Strange: we can't decode the block handle in the index block.
259		// We'll just return the offset of the metaindex block, which is
260		// close to the whole file size for this case.
261	0	result = rep_->metaindex_handle.offset();
262	0	}
263	0	} else {
264		// key is past the last key in the file. Approximate the offset
265		// by returning the offset of the metaindex block (which is
266		// right near the end of the file).
267	0	result = rep_->metaindex_handle.offset();
268	0	}
269	0	delete index_iter;
270	0	return result;
271	0	}
272
273		} // namespace leveldb