36a5f8ed7f
- Replace raw slice comparison with a call to user comparator.
Added test for custom comparators.
- Fix end of namespace comments.
- Fixed bug in picking inputs for a level-0 compaction.
When finding overlapping files, the covered range may expand
as files are added to the input set. We now correctly expand
the range when this happens instead of continuing to use the
old range. For example, suppose L0 contains files with the
following ranges:
F1: a .. d
F2: c .. g
F3: f .. j
and the initial compaction target is F3. We used to search
for range f..j which yielded {F2,F3}. However we now expand
the range as soon as another file is added. In this case,
when F2 is added, we expand the range to c..j and restart the
search. That picks up file F1 as well.
This change fixes a bug related to deleted keys showing up
incorrectly after a compaction as described in Issue 44.
(Sync with upstream @25072954)
110 lines
3.1 KiB
C++
110 lines
3.1 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.
|
|
//
|
|
// Slice is a simple structure containing a pointer into some external
|
|
// storage and a size. The user of a Slice must ensure that the slice
|
|
// is not used after the corresponding external storage has been
|
|
// deallocated.
|
|
//
|
|
// Multiple threads can invoke const methods on a Slice without
|
|
// external synchronization, but if any of the threads may call a
|
|
// non-const method, all threads accessing the same Slice must use
|
|
// external synchronization.
|
|
|
|
#ifndef STORAGE_LEVELDB_INCLUDE_SLICE_H_
|
|
#define STORAGE_LEVELDB_INCLUDE_SLICE_H_
|
|
|
|
#include <assert.h>
|
|
#include <stddef.h>
|
|
#include <string.h>
|
|
#include <string>
|
|
|
|
namespace leveldb {
|
|
|
|
class Slice {
|
|
public:
|
|
// Create an empty slice.
|
|
Slice() : data_(""), size_(0) { }
|
|
|
|
// Create a slice that refers to d[0,n-1].
|
|
Slice(const char* d, size_t n) : data_(d), size_(n) { }
|
|
|
|
// Create a slice that refers to the contents of "s"
|
|
Slice(const std::string& s) : data_(s.data()), size_(s.size()) { }
|
|
|
|
// Create a slice that refers to s[0,strlen(s)-1]
|
|
Slice(const char* s) : data_(s), size_(strlen(s)) { }
|
|
|
|
// Return a pointer to the beginning of the referenced data
|
|
const char* data() const { return data_; }
|
|
|
|
// Return the length (in bytes) of the referenced data
|
|
size_t size() const { return size_; }
|
|
|
|
// Return true iff the length of the referenced data is zero
|
|
bool empty() const { return size_ == 0; }
|
|
|
|
// Return the ith byte in the referenced data.
|
|
// REQUIRES: n < size()
|
|
char operator[](size_t n) const {
|
|
assert(n < size());
|
|
return data_[n];
|
|
}
|
|
|
|
// Change this slice to refer to an empty array
|
|
void clear() { data_ = ""; size_ = 0; }
|
|
|
|
// Drop the first "n" bytes from this slice.
|
|
void remove_prefix(size_t n) {
|
|
assert(n <= size());
|
|
data_ += n;
|
|
size_ -= n;
|
|
}
|
|
|
|
// Return a string that contains the copy of the referenced data.
|
|
std::string ToString() const { return std::string(data_, size_); }
|
|
|
|
// Three-way comparison. Returns value:
|
|
// < 0 iff "*this" < "b",
|
|
// == 0 iff "*this" == "b",
|
|
// > 0 iff "*this" > "b"
|
|
int compare(const Slice& b) const;
|
|
|
|
// Return true iff "x" is a prefix of "*this"
|
|
bool starts_with(const Slice& x) const {
|
|
return ((size_ >= x.size_) &&
|
|
(memcmp(data_, x.data_, x.size_) == 0));
|
|
}
|
|
|
|
private:
|
|
const char* data_;
|
|
size_t size_;
|
|
|
|
// Intentionally copyable
|
|
};
|
|
|
|
inline bool operator==(const Slice& x, const Slice& y) {
|
|
return ((x.size() == y.size()) &&
|
|
(memcmp(x.data(), y.data(), x.size()) == 0));
|
|
}
|
|
|
|
inline bool operator!=(const Slice& x, const Slice& y) {
|
|
return !(x == y);
|
|
}
|
|
|
|
inline int Slice::compare(const Slice& b) const {
|
|
const int min_len = (size_ < b.size_) ? size_ : b.size_;
|
|
int r = memcmp(data_, b.data_, min_len);
|
|
if (r == 0) {
|
|
if (size_ < b.size_) r = -1;
|
|
else if (size_ > b.size_) r = +1;
|
|
}
|
|
return r;
|
|
}
|
|
|
|
} // namespace leveldb
|
|
|
|
|
|
#endif // STORAGE_LEVELDB_INCLUDE_SLICE_H_
|