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levedb-mcpe-legacy/util/testutil.h
Sanjay Ghemawat 1b7c4ce89d LevelDB now attempts to reuse the preceding MANIFEST and log file when re-opened.
(Based on a suggestion by cmumford.)

"open" benchmark on my workstation speeds up significantly since we
can now avoid three fdatasync calls and a compaction per open:

  Before: ~80000 microseconds
  After:    ~130 microseconds

Details:

(1) Added Options::reuse_logs (currently defaults to false) to control
new behavior.  The intention is to change the default to true after some
baking.

(2) Added Env::NewAppendableFile() whose default implementation returns
a not-supported error.

(3) VersionSet::Recovery attempts to reuse the MANIFEST from which
it is recovering.

(4) DBImpl recovery attempts to reuse the last log file and memtable.

(5) db_test.cc now tests a new configuration that sets reuse_logs to true.

(6) fault_injection_test also tests a reuse_logs==true config.

(7) Added a new recovery_test.
2016-04-07 17:45:03 +02:00

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2.0 KiB
C++

// 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_UTIL_TESTUTIL_H_
#define STORAGE_LEVELDB_UTIL_TESTUTIL_H_
#include "leveldb/env.h"
#include "leveldb/slice.h"
#include "util/random.h"
namespace leveldb {
namespace test {
// Store in *dst a random string of length "len" and return a Slice that
// references the generated data.
extern Slice RandomString(Random* rnd, int len, std::string* dst);
// Return a random key with the specified length that may contain interesting
// characters (e.g. \x00, \xff, etc.).
extern std::string RandomKey(Random* rnd, int len);
// Store in *dst a string of length "len" that will compress to
// "N*compressed_fraction" bytes and return a Slice that references
// the generated data.
extern Slice CompressibleString(Random* rnd, double compressed_fraction,
size_t len, std::string* dst);
// A wrapper that allows injection of errors.
class ErrorEnv : public EnvWrapper {
public:
bool writable_file_error_;
int num_writable_file_errors_;
ErrorEnv() : EnvWrapper(Env::Default()),
writable_file_error_(false),
num_writable_file_errors_(0) { }
virtual Status NewWritableFile(const std::string& fname,
WritableFile** result) {
if (writable_file_error_) {
++num_writable_file_errors_;
*result = NULL;
return Status::IOError(fname, "fake error");
}
return target()->NewWritableFile(fname, result);
}
virtual Status NewAppendableFile(const std::string& fname,
WritableFile** result) {
if (writable_file_error_) {
++num_writable_file_errors_;
*result = NULL;
return Status::IOError(fname, "fake error");
}
return target()->NewAppendableFile(fname, result);
}
};
} // namespace test
} // namespace leveldb
#endif // STORAGE_LEVELDB_UTIL_TESTUTIL_H_