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rocksdb/util/testutil.h

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// Copyright (c) 2013, Facebook, Inc. All rights reserved.
// This source code is licensed under the BSD-style license found in the
// LICENSE file in the root directory of this source tree. An additional grant
// of patent rights can be found in the PATENTS file in the same directory.
//
// 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.
#pragma once
#include <string>
#include "db/dbformat.h"
#include "rocksdb/env.h"
#include "rocksdb/slice.h"
#include "util/random.h"
namespace rocksdb {
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);
extern std::string RandomHumanReadableString(Random* rnd, int len);
// 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,
int 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,
unique_ptr<WritableFile>* result,
const EnvOptions& soptions) {
result->reset();
if (writable_file_error_) {
++num_writable_file_errors_;
return Status::IOError(fname, "fake error");
}
return target()->NewWritableFile(fname, result, soptions);
}
};
// An internal comparator that just forward comparing results from the
// user comparator in it. Can be used to test entities that have no dependency
// on internal key structure but consumes InternalKeyComparator, like
// BlockBasedTable.
class PlainInternalKeyComparator : public InternalKeyComparator {
public:
explicit PlainInternalKeyComparator(const Comparator* c)
: InternalKeyComparator(c) {}
virtual ~PlainInternalKeyComparator() {}
virtual int Compare(const Slice& a, const Slice& b) const override {
return user_comparator()->Compare(a, b);
}
virtual void FindShortestSeparator(std::string* start,
const Slice& limit) const override {
user_comparator()->FindShortestSeparator(start, limit);
}
virtual void FindShortSuccessor(std::string* key) const override {
user_comparator()->FindShortSuccessor(key);
}
};
// A test comparator which compare two strings in this way:
// (1) first compare prefix of 8 bytes in alphabet order,
// (2) if two strings share the same prefix, sort the other part of the string
// in the reverse alphabet order.
// This helps simulate the case of compounded key of [entity][timestamp] and
// latest timestamp first.
class SimpleSuffixReverseComparator : public Comparator {
public:
SimpleSuffixReverseComparator() {}
virtual const char* Name() const { return "SimpleSuffixReverseComparator"; }
virtual int Compare(const Slice& a, const Slice& b) const {
Slice prefix_a = Slice(a.data(), 8);
Slice prefix_b = Slice(b.data(), 8);
int prefix_comp = prefix_a.compare(prefix_b);
if (prefix_comp != 0) {
return prefix_comp;
} else {
Slice suffix_a = Slice(a.data() + 8, a.size() - 8);
Slice suffix_b = Slice(b.data() + 8, b.size() - 8);
return -(suffix_a.compare(suffix_b));
}
}
virtual void FindShortestSeparator(std::string* start,
const Slice& limit) const {}
virtual void FindShortSuccessor(std::string* key) const {}
};
// Returns a user key comparator that can be used for comparing two uint64_t
// slices. Instead of comparing slices byte-wise, it compares all the 8 bytes
// at once. Assumes same endian-ness is used though the database's lifetime.
// Symantics of comparison would differ from Bytewise comparator in little
// endian machines.
extern const Comparator* Uint64Comparator();
} // namespace test
} // namespace rocksdb