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/* -*- Mode: C++ -*- */
namespace regtest {
class Segment {
public:
Segment(uint32_t seed, size_t length)
: seed(seed),
length(length),
seed_offset(0) { }
uint32_t seed; // Seed used for generating byte sequence
size_t length; // Length of this segment
size_t seed_offset; // Seed positions the sequence this many bytes
// before its beginning.
};
typedef map<xoff_t, Segment> SegmentMap;
class Block;
class BlockIterator;
class FileSpec {
public:
FileSpec(MTRandom *rand)
: rand_(rand) {
}
// Generates a file with a known size
void GenerateFixedSize(xoff_t size) {
Reset();
for (xoff_t p = 0; p < size; ) {
xoff_t t = min(Constants::BLOCK_SIZE, size - p);
table_.insert(make_pair(p, Segment(rand_->Rand32(), t)));
p += t;
}
}
// Generates a file with exponential-random distributed size
void GenerateRandomSize(xoff_t mean) {
GenerateFixedSize(rand_->ExpRand(mean));
}
// Returns the size of the file
xoff_t Size() const {
if (table_.empty()) {
return 0;
}
SegmentMap::const_iterator i = --table_.end();
return i->first + i->second.length;
}
// Returns the number of blocks
xoff_t Blocks(size_t blksize = Constants::BLOCK_SIZE) const {
if (table_.empty()) {
return 0;
}
return ((Size() - 1) / blksize) + 1;
}
// Returns the number of segments
xoff_t Segments() const {
return table_.size();
}
// Create a mutation according to "what".
template <typename T>
void ModifyTo(FileSpec *modify) const {
modify->table_ = table_;
T::Mutate(&modify->table_, rand_);
}
void Reset() {
table_.clear();
}
typedef BlockIterator iterator;
private:
friend class BlockIterator;
MTRandom *rand_;
SegmentMap table_;
};
class Block {
public:
Block()
: data_(NULL),
data_size_(0),
size_(0) { }
~Block() {
if (data_) {
delete [] data_;
}
}
size_t Size() const {
return size_;
}
uint8_t operator[](size_t i) const {
CHECK_LT(i, size_);
return data_[i];
}
uint8_t* Data() const {
return data_;
}
// For writing to blocks
void Append(const uint8_t *data, size_t size);
// For cleaing a block
void Reset() {
size_ = 0;
}
private:
void SetSize(size_t size) {
size_ = size;
if (data_size_ < size) {
if (data_) {
delete [] data_;
}
data_ = new uint8_t[size];
data_size_ = size;
}
}
friend class BlockIterator;
uint8_t *data_;
size_t data_size_;
size_t size_;
};
class BlockIterator {
public:
explicit BlockIterator(const FileSpec& spec)
: spec_(spec),
blkno_(0),
blksize_(Constants::BLOCK_SIZE) { }
BlockIterator(const FileSpec& spec,
size_t blksize)
: spec_(spec),
blkno_(0),
blksize_(blksize) { }
bool Done() const {
return blkno_ >= spec_.Blocks(blksize_);
}
void Next() {
blkno_++;
}
xoff_t Blkno() const {
return blkno_;
}
void SetBlock(xoff_t blkno) {
blkno_ = blkno;
}
void Get(Block *block) const;
size_t BytesOnBlock() const {
xoff_t blocks = spec_.Blocks(blksize_);
xoff_t size = spec_.Size();
CHECK((blkno_ < blocks) ||
(blkno_ == blocks && size % blksize_ == 0));
if (blkno_ == blocks) {
return 0;
}
if (blkno_ + 1 == blocks) {
return ((size - 1) % blksize_) + 1;
}
return blksize_;
}
size_t BlockSize() const {
return blksize_;
}
private:
const FileSpec& spec_;
xoff_t blkno_;
size_t blksize_;
};
inline void BlockIterator::Get(Block *block) const {
xoff_t offset = blkno_ * blksize_;
const SegmentMap &table = spec_.table_;
size_t got = 0;
block->SetSize(BytesOnBlock());
SegmentMap::const_iterator pos = table.upper_bound(offset);
--pos;
while (got < block->size_) {
CHECK(pos != table.end());
CHECK_GE(offset, pos->first);
// The position of this segment may start before this block starts,
// and then the position of the data may be offset from the seeding
// position.
size_t seg_offset = offset - pos->first;
xoff_t skip = seg_offset + pos->second.seed_offset;
MTRandom gen(pos->second.seed);
while (skip--) {
gen.Rand32();
}
for (size_t i = seg_offset; i < pos->second.length; i++) {
CHECK_LT(got, blksize_);
block->data_[got++] = gen.Rand32();
}
offset += (pos->second.length - seg_offset);
++pos;
}
}
inline void Block::Append(const uint8_t *data, size_t size) {
if (data_ == NULL) {
CHECK_EQ(0, size_);
CHECK_EQ(0, data_size_);
data_ = new uint8_t[Constants::BLOCK_SIZE];
data_size_ = Constants::BLOCK_SIZE;
}
if (size_ + size > data_size_) {
uint8_t *tmp = data_;
while (size_ + size > data_size_) {
data_size_ *= 2;
}
data_ = new uint8_t[data_size_];
memcpy(data_, tmp, size_);
delete tmp;
}
memcpy(data_ + size_, data, size);
size_ += size;
}
} // namespace regtest
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