Files
scylladb/sstables/sstables.cc
Avi Kivity 3a5e3c8829 sstables: de-futurize write path
The sstables write path has been partially de-futurized, but now creates a
ton of threads, and yet does not exploit this as everything is serialized.

Remove those extra threads and futures and use a single thread to write
everything.  If needed, we'll employ write-behind in output_stream to
increase parallelism.

Reviewed-by: Nadav Har'El <nyh@cloudius-systems.com>
2015-08-03 20:33:59 +03:00

1465 lines
54 KiB
C++

/*
* Copyright 2015 Cloudius Systems
*/
#include "log.hh"
#include <vector>
#include <typeinfo>
#include <limits>
#include "core/future.hh"
#include "core/future-util.hh"
#include "core/sstring.hh"
#include "core/fstream.hh"
#include "core/shared_ptr.hh"
#include "core/do_with.hh"
#include "core/thread.hh"
#include <iterator>
#include "types.hh"
#include "sstables.hh"
#include "compress.hh"
#include "unimplemented.hh"
#include <boost/algorithm/string.hpp>
namespace sstables {
logging::logger sstlog("sstable");
class random_access_reader {
input_stream<char> _in;
protected:
virtual input_stream<char> open_at(uint64_t pos) = 0;
public:
future<temporary_buffer<char>> read_exactly(size_t n) {
return _in.read_exactly(n);
}
void seek(uint64_t pos) {
_in = open_at(pos);
}
bool eof() { return _in.eof(); }
virtual ~random_access_reader() { }
};
class file_random_access_reader : public random_access_reader {
file _file;
size_t _buffer_size;
public:
virtual input_stream<char> open_at(uint64_t pos) override {
return make_file_input_stream(_file, pos, _buffer_size);
}
explicit file_random_access_reader(file f, size_t buffer_size = 8192)
: _file(std::move(f)), _buffer_size(buffer_size)
{
seek(0);
}
~file_random_access_reader() {
_file.close().handle_exception([save = _file] (auto ep) {
sstlog.warn("sstable close failed: {}", ep);
});
}
};
class shared_file_random_access_reader : public random_access_reader {
file _file;
size_t _buffer_size;
public:
virtual input_stream<char> open_at(uint64_t pos) override {
return make_file_input_stream(_file, pos, _buffer_size);
}
explicit shared_file_random_access_reader(file f, size_t buffer_size = 8192)
: _file(std::move(f)), _buffer_size(buffer_size)
{
seek(0);
}
};
std::unordered_map<sstable::version_types, sstring, enum_hash<sstable::version_types>> sstable::_version_string = {
{ sstable::version_types::la , "la" }
};
std::unordered_map<sstable::format_types, sstring, enum_hash<sstable::format_types>> sstable::_format_string = {
{ sstable::format_types::big , "big" }
};
std::unordered_map<sstable::component_type, sstring, enum_hash<sstable::component_type>> sstable::_component_map = {
{ component_type::Index, "Index.db"},
{ component_type::CompressionInfo, "CompressionInfo.db" },
{ component_type::Data, "Data.db" },
{ component_type::TOC, "TOC.txt" },
{ component_type::Summary, "Summary.db" },
{ component_type::Digest, "Digest.sha1" },
{ component_type::CRC, "CRC.db" },
{ component_type::Filter, "Filter.db" },
{ component_type::Statistics, "Statistics.db" },
};
// This assumes that the mappings are small enough, and called unfrequent
// enough. If that changes, it would be adviseable to create a full static
// reverse mapping, even if it is done at runtime.
template <typename Map>
static typename Map::key_type reverse_map(const typename Map::mapped_type& value, Map& map) {
for (auto& pair: map) {
if (pair.second == value) {
return pair.first;
}
}
throw std::out_of_range("unable to reverse map");
}
struct bufsize_mismatch_exception : malformed_sstable_exception {
bufsize_mismatch_exception(size_t size, size_t expected) :
malformed_sstable_exception(sprint("Buffer improperly sized to hold requested data. Got: %ld. Expected: %ld", size, expected))
{}
};
// This should be used every time we use read_exactly directly.
//
// read_exactly is a lot more convenient of an interface to use, because we'll
// be parsing known quantities.
//
// However, anything other than the size we have asked for, is certainly a bug,
// and we need to do something about it.
static void check_buf_size(temporary_buffer<char>& buf, size_t expected) {
if (buf.size() < expected) {
throw bufsize_mismatch_exception(buf.size(), expected);
}
}
template <typename T, typename U>
static void check_truncate_and_assign(T& to, const U from) {
static_assert(std::is_integral<T>::value && std::is_integral<U>::value, "T and U must be integral");
to = from;
if (to != from) {
throw std::overflow_error("assigning U to T caused an overflow");
}
}
// Base parser, parses an integer type
template <typename T>
typename std::enable_if_t<std::is_integral<T>::value, void>
read_integer(temporary_buffer<char>& buf, T& i) {
auto *nr = reinterpret_cast<const net::packed<T> *>(buf.get());
i = net::ntoh(*nr);
}
template <typename T>
typename std::enable_if_t<std::is_integral<T>::value, future<>>
parse(random_access_reader& in, T& i) {
return in.read_exactly(sizeof(T)).then([&i] (auto buf) {
check_buf_size(buf, sizeof(T));
read_integer(buf, i);
return make_ready_future<>();
});
}
template <typename T>
inline typename std::enable_if_t<std::is_integral<T>::value, void>
write(file_writer& out, T i) {
auto *nr = reinterpret_cast<const net::packed<T> *>(&i);
i = net::hton(*nr);
auto p = reinterpret_cast<const char*>(&i);
out.write(p, sizeof(T)).get();
}
template <typename T>
typename std::enable_if_t<std::is_enum<T>::value, future<>>
parse(random_access_reader& in, T& i) {
return parse(in, reinterpret_cast<typename std::underlying_type<T>::type&>(i));
}
template <typename T>
inline typename std::enable_if_t<std::is_enum<T>::value, void>
write(file_writer& out, T i) {
write(out, static_cast<typename std::underlying_type<T>::type>(i));
}
future<> parse(random_access_reader& in, bool& i) {
return parse(in, reinterpret_cast<uint8_t&>(i));
}
inline void write(file_writer& out, bool i) {
write(out, static_cast<uint8_t>(i));
}
template <typename To, typename From>
static inline To convert(From f) {
static_assert(sizeof(To) == sizeof(From), "Sizes must match");
union {
To to;
From from;
} conv;
conv.from = f;
return conv.to;
}
future<> parse(random_access_reader& in, double& d) {
return in.read_exactly(sizeof(double)).then([&d] (auto buf) {
check_buf_size(buf, sizeof(double));
auto *nr = reinterpret_cast<const net::packed<unsigned long> *>(buf.get());
d = convert<double>(net::ntoh(*nr));
return make_ready_future<>();
});
}
inline void write(file_writer& out, double d) {
auto *nr = reinterpret_cast<const net::packed<unsigned long> *>(&d);
auto tmp = net::hton(*nr);
auto p = reinterpret_cast<const char*>(&tmp);
out.write(p, sizeof(unsigned long)).get();
}
template <typename T>
future<> parse(random_access_reader& in, T& len, bytes& s) {
return in.read_exactly(len).then([&s, len] (auto buf) {
check_buf_size(buf, len);
// Likely a different type of char. Most bufs are unsigned, whereas the bytes type is signed.
s = bytes(reinterpret_cast<const bytes::value_type *>(buf.get()), len);
});
}
inline void write(file_writer& out, bytes& s) {
out.write(s).get();
}
inline void write(file_writer& out, bytes_view s) {
out.write(reinterpret_cast<const char*>(s.data()), s.size()).get();
}
// All composite parsers must come after this
template<typename First, typename... Rest>
future<> parse(random_access_reader& in, First& first, Rest&&... rest) {
return parse(in, first).then([&in, &rest...] {
return parse(in, std::forward<Rest>(rest)...);
});
}
template<typename First, typename... Rest>
inline void write(file_writer& out, First& first, Rest&&... rest) {
write(out, first);
write(out, std::forward<Rest>(rest)...);
}
// Intended to be used for a type that describes itself through describe_type().
template <class T>
typename std::enable_if_t<!std::is_integral<T>::value && !std::is_enum<T>::value, future<>>
parse(random_access_reader& in, T& t) {
return t.describe_type([&in] (auto&&... what) -> future<> {
return parse(in, what...);
});
}
template <class T>
inline typename std::enable_if_t<!std::is_integral<T>::value && !std::is_enum<T>::value, void>
write(file_writer& out, T& t) {
t.describe_type([&out] (auto&&... what) -> void {
write(out, std::forward<decltype(what)>(what)...);
});
}
// For all types that take a size, we provide a template that takes the type
// alone, and another, separate one, that takes a size parameter as well, of
// type Size. This is because although most of the time the size and the data
// are contiguous, it is not always the case. So we want to have the
// flexibility of parsing them separately.
template <typename Size>
future<> parse(random_access_reader& in, disk_string<Size>& s) {
auto len = std::make_unique<Size>();
auto f = parse(in, *len);
return f.then([&in, &s, len = std::move(len)] {
return parse(in, *len, s.value);
});
}
template <typename Size>
inline void write(file_writer& out, disk_string<Size>& s) {
Size len = 0;
check_truncate_and_assign(len, s.value.size());
write(out, len);
write(out, s.value);
}
template <typename Size>
inline void write(file_writer& out, disk_string_view<Size>& s) {
Size len;
check_truncate_and_assign(len, s.value.size());
write(out, len, s.value);
}
// We cannot simply read the whole array at once, because we don't know its
// full size. We know the number of elements, but if we are talking about
// disk_strings, for instance, we have no idea how much of the stream each
// element will take.
//
// Sometimes we do know the size, like the case of integers. There, all we have
// to do is to convert each member because they are all stored big endian.
// We'll offer a specialization for that case below.
template <typename Size, typename Members>
typename std::enable_if_t<!std::is_integral<Members>::value, future<>>
parse(random_access_reader& in, Size& len, std::vector<Members>& arr) {
auto count = make_lw_shared<size_t>(0);
auto eoarr = [count, len] { return *count == len; };
return do_until(eoarr, [count, &in, &arr] {
return parse(in, arr[(*count)++]);
});
}
template <typename Size, typename Members>
typename std::enable_if_t<std::is_integral<Members>::value, future<>>
parse(random_access_reader& in, Size& len, std::vector<Members>& arr) {
return in.read_exactly(len * sizeof(Members)).then([&arr, len] (auto buf) {
check_buf_size(buf, len * sizeof(Members));
auto *nr = reinterpret_cast<const net::packed<Members> *>(buf.get());
for (size_t i = 0; i < len; ++i) {
arr[i] = net::ntoh(nr[i]);
}
return make_ready_future<>();
});
}
// We resize the array here, before we pass it to the integer / non-integer
// specializations
template <typename Size, typename Members>
future<> parse(random_access_reader& in, disk_array<Size, Members>& arr) {
auto len = std::make_unique<Size>();
auto f = parse(in, *len);
return f.then([&in, &arr, len = std::move(len)] {
arr.elements.resize(*len);
return parse(in, *len, arr.elements);
});
}
template <typename Members>
inline typename std::enable_if_t<!std::is_integral<Members>::value, void>
write(file_writer& out, std::vector<Members>& arr) {
for (auto& a : arr) {
write(out, a);
}
}
template <typename Members>
inline typename std::enable_if_t<std::is_integral<Members>::value, void>
write(file_writer& out, std::vector<Members>& arr) {
std::vector<Members> tmp;
tmp.resize(arr.size());
// copy arr into tmp converting each entry into big-endian representation.
auto *nr = reinterpret_cast<const net::packed<Members> *>(arr.data());
for (size_t i = 0; i < arr.size(); i++) {
tmp[i] = net::hton(nr[i]);
}
auto p = reinterpret_cast<const char*>(tmp.data());
auto bytes = tmp.size() * sizeof(Members);
out.write(p, bytes).get();
}
template <typename Size, typename Members>
inline void write(file_writer& out, disk_array<Size, Members>& arr) {
Size len = 0;
check_truncate_and_assign(len, arr.elements.size());
write(out, len);
write(out, arr.elements);
}
template <typename Size, typename Key, typename Value>
future<> parse(random_access_reader& in, Size& len, std::unordered_map<Key, Value>& map) {
return do_with(Size(), [&in, len, &map] (Size& count) {
auto eos = [len, &count] { return len == count++; };
return do_until(eos, [len, &in, &map] {
struct kv {
Key key;
Value value;
};
return do_with(kv(), [&in, &map] (auto& el) {
return parse(in, el.key, el.value).then([&el, &map] {
map.emplace(el.key, el.value);
});
});
});
});
}
template <typename Size, typename Key, typename Value>
future<> parse(random_access_reader& in, disk_hash<Size, Key, Value>& h) {
auto w = std::make_unique<Size>();
auto f = parse(in, *w);
return f.then([&in, &h, w = std::move(w)] {
return parse(in, *w, h.map);
});
}
template <typename Key, typename Value>
inline void write(file_writer& out, std::unordered_map<Key, Value>& map) {
for (auto& val: map) {
write(out, val.first, val.second);
};
}
template <typename Size, typename Key, typename Value>
inline void write(file_writer& out, disk_hash<Size, Key, Value>& h) {
Size len = 0;
check_truncate_and_assign(len, h.map.size());
write(out, len);
write(out, h.map);
}
future<> parse(random_access_reader& in, summary& s) {
using pos_type = typename decltype(summary::positions)::value_type;
return parse(in, s.header.min_index_interval,
s.header.size,
s.header.memory_size,
s.header.sampling_level,
s.header.size_at_full_sampling).then([&in, &s] {
return in.read_exactly(s.header.size * sizeof(pos_type)).then([&in, &s] (auto buf) {
auto len = s.header.size * sizeof(pos_type);
check_buf_size(buf, len);
s.entries.resize(s.header.size);
auto *nr = reinterpret_cast<const pos_type *>(buf.get());
s.positions = std::vector<pos_type>(nr, nr + s.header.size);
// Since the keys in the index are not sized, we need to calculate
// the start position of the index i+1 to determine the boundaries
// of index i. The "memory_size" field in the header determines the
// total memory used by the map, so if we push it to the vector, we
// can guarantee that no conditionals are used, and we can always
// query the position of the "next" index.
s.positions.push_back(s.header.memory_size);
}).then([&in, &s] {
in.seek(sizeof(summary::header) + s.header.memory_size);
return parse(in, s.first_key, s.last_key);
}).then([&in, &s] {
in.seek(s.positions[0] + sizeof(summary::header));
assert(s.positions.size() == (s.entries.size() + 1));
auto idx = make_lw_shared<size_t>(0);
return do_for_each(s.entries.begin(), s.entries.end(), [idx, &in, &s] (auto& entry) {
auto pos = s.positions[(*idx)++];
auto next = s.positions[*idx];
auto entrysize = next - pos;
return in.read_exactly(entrysize).then([&entry, entrysize] (auto buf) {
check_buf_size(buf, entrysize);
auto keysize = entrysize - 8;
entry.key = bytes(reinterpret_cast<const int8_t*>(buf.get()), keysize);
buf.trim_front(keysize);
// FIXME: This is a le read. We should make this explicit
entry.position = *(reinterpret_cast<const net::packed<uint64_t> *>(buf.get()));
return make_ready_future<>();
});
}).then([&s] {
// Delete last element which isn't part of the on-disk format.
s.positions.pop_back();
});
});
});
}
inline void write(file_writer& out, summary_entry& entry) {
// FIXME: summary entry is supposedly written in memory order, but that
// would prevent portability of summary file between machines of different
// endianness. We can treat it as little endian to preserve portability.
write(out, entry.key);
auto p = reinterpret_cast<const char*>(&entry.position);
out.write(p, sizeof(uint64_t)).get();
}
inline void write(file_writer& out, summary& s) {
using pos_type = typename decltype(summary::positions)::value_type;
// NOTE: positions and entries must be stored in NATIVE BYTE ORDER, not BIG-ENDIAN.
write(out, s.header.min_index_interval,
s.header.size,
s.header.memory_size,
s.header.sampling_level,
s.header.size_at_full_sampling);
auto p = reinterpret_cast<const char*>(s.positions.data());
out.write(p, sizeof(pos_type) * s.positions.size()).get();
write(out, s.entries);
write(out, s.first_key, s.last_key);
}
future<summary_entry&> sstable::read_summary_entry(size_t i) {
// The last one is the boundary marker
if (i >= (_summary.entries.size())) {
throw std::out_of_range(sprint("Invalid Summary index: %ld", i));
}
return make_ready_future<summary_entry&>(_summary.entries[i]);
}
future<> parse(random_access_reader& in, index_entry& ie) {
return parse(in, ie.key, ie.position, ie.promoted_index);
}
future<> parse(random_access_reader& in, deletion_time& d) {
return parse(in, d.local_deletion_time, d.marked_for_delete_at);
}
template <typename Child>
future<> parse(random_access_reader& in, std::unique_ptr<metadata>& p) {
p.reset(new Child);
return parse(in, *static_cast<Child *>(p.get()));
}
template <typename Child>
inline void write(file_writer& out, std::unique_ptr<metadata>& p) {
write(out, *static_cast<Child *>(p.get()));
}
future<> parse(random_access_reader& in, statistics& s) {
return parse(in, s.hash).then([&in, &s] {
return do_for_each(s.hash.map.begin(), s.hash.map.end(), [&in, &s] (auto val) mutable {
in.seek(val.second);
switch (val.first) {
case metadata_type::Validation:
return parse<validation_metadata>(in, s.contents[val.first]);
case metadata_type::Compaction:
return parse<compaction_metadata>(in, s.contents[val.first]);
case metadata_type::Stats:
return parse<stats_metadata>(in, s.contents[val.first]);
default:
sstlog.warn("Invalid metadata type at Statistics file: {} ", int(val.first));
return make_ready_future<>();
}
});
});
}
inline void write(file_writer& out, statistics& s) {
write(out, s.hash);
struct kv {
metadata_type key;
uint32_t value;
};
// sort map by file offset value and store the result into a vector.
// this is indeed needed because output stream cannot afford random writes.
auto v = make_shared<std::vector<kv>>();
v->reserve(s.hash.map.size());
for (auto val : s.hash.map) {
kv tmp = { val.first, val.second };
v->push_back(tmp);
}
std::sort(v->begin(), v->end(), [] (kv i, kv j) { return i.value < j.value; });
for (auto& val: *v) {
switch (val.key) {
case metadata_type::Validation:
write<validation_metadata>(out, s.contents[val.key]);
break;
case metadata_type::Compaction:
write<compaction_metadata>(out, s.contents[val.key]);
break;
case metadata_type::Stats:
write<stats_metadata>(out, s.contents[val.key]);
break;
default:
sstlog.warn("Invalid metadata type at Statistics file: {} ", int(val.key));
return; // FIXME: should throw
}
}
}
future<> parse(random_access_reader& in, estimated_histogram& eh) {
auto len = std::make_unique<uint32_t>();
auto f = parse(in, *len);
return f.then([&in, &eh, len = std::move(len)] {
uint32_t length = *len;
assert(length > 0);
eh.bucket_offsets.resize(length - 1);
eh.buckets.resize(length);
auto type_size = sizeof(uint64_t) * 2;
return in.read_exactly(length * type_size).then([&eh, length, type_size] (auto buf) {
check_buf_size(buf, length * type_size);
auto *nr = reinterpret_cast<const net::packed<uint64_t> *>(buf.get());
size_t j = 0;
for (size_t i = 0; i < length; ++i) {
eh.bucket_offsets[i == 0 ? 0 : i - 1] = net::ntoh(nr[j++]);
eh.buckets[i] = net::ntoh(nr[j++]);
}
return make_ready_future<>();
});
});
}
inline void write(file_writer& out, estimated_histogram& eh) {
uint32_t len = 0;
check_truncate_and_assign(len, eh.buckets.size());
write(out, len);
struct element {
uint64_t offsets;
uint64_t buckets;
};
std::vector<element> elements;
elements.resize(eh.buckets.size());
auto *offsets_nr = reinterpret_cast<const net::packed<uint64_t> *>(eh.bucket_offsets.data());
auto *buckets_nr = reinterpret_cast<const net::packed<uint64_t> *>(eh.buckets.data());
for (size_t i = 0; i < eh.buckets.size(); i++) {
elements[i].offsets = net::hton(offsets_nr[i == 0 ? 0 : i - 1]);
elements[i].buckets = net::hton(buckets_nr[i]);
}
auto p = reinterpret_cast<const char*>(elements.data());
auto bytes = elements.size() * sizeof(element);
out.write(p, bytes).get();
}
// This is small enough, and well-defined. Easier to just read it all
// at once
future<> sstable::read_toc() {
auto file_path = filename(sstable::component_type::TOC);
sstlog.debug("Reading TOC file {} ", file_path);
return engine().open_file_dma(file_path, open_flags::ro).then([this] (file f) {
auto bufptr = allocate_aligned_buffer<char>(4096, 4096);
auto buf = bufptr.get();
auto fut = f.dma_read(0, buf, 4096);
return std::move(fut).then([this, f = std::move(f), bufptr = std::move(bufptr)] (size_t size) mutable {
// This file is supposed to be very small. Theoretically we should check its size,
// but if we so much as read a whole page from it, there is definitely something fishy
// going on - and this simplifies the code.
if (size >= 4096) {
throw malformed_sstable_exception("SSTable too big: " + to_sstring(size) + " bytes.");
}
std::experimental::string_view buf(bufptr.get(), size);
std::vector<sstring> comps;
boost::split(comps , buf, boost::is_any_of("\n"));
for (auto& c: comps) {
// accept trailing newlines
if (c == "") {
continue;
}
try {
_components.insert(reverse_map(c, _component_map));
} catch (std::out_of_range& oor) {
throw malformed_sstable_exception("Unrecognized TOC component: " + c);
}
}
if (!_components.size()) {
throw malformed_sstable_exception("Empty TOC");
}
return f.close().finally([f] {});
});
}).then_wrapped([file_path] (future<> f) {
try {
f.get();
} catch (std::system_error& e) {
if (e.code() == std::error_code(ENOENT, std::system_category())) {
throw malformed_sstable_exception(file_path + ": file not found");
}
}
});
}
void sstable::write_toc() {
auto file_path = filename(sstable::component_type::TOC);
sstlog.debug("Writing TOC file {} ", file_path);
file f = engine().open_file_dma(file_path, open_flags::wo | open_flags::create | open_flags::truncate).get0();
auto out = file_writer(std::move(f), 4096);
auto w = file_writer(std::move(out));
for (auto&& key : _components) {
// new line character is appended to the end of each component name.
auto value = _component_map[key] + "\n";
bytes b = bytes(reinterpret_cast<const bytes::value_type *>(value.c_str()), value.size());
write(w, b);
}
w.flush().get();
w.close().get();
}
void write_crc(const sstring file_path, checksum& c) {
sstlog.debug("Writing CRC file {} ", file_path);
auto oflags = open_flags::wo | open_flags::create | open_flags::exclusive;
file f = engine().open_file_dma(file_path, oflags).get0();
auto out = file_writer(std::move(f), 4096);
auto w = file_writer(std::move(out));
write(w, c);
w.close().get();
}
// Digest file stores the full checksum of data file converted into a string.
void write_digest(const sstring file_path, uint32_t full_checksum) {
sstlog.debug("Writing Digest file {} ", file_path);
auto oflags = open_flags::wo | open_flags::create | open_flags::exclusive;
auto f = engine().open_file_dma(file_path, oflags).get0();
auto out = file_writer(std::move(f), 4096);
auto w = file_writer(std::move(out));
auto digest = to_sstring<bytes>(full_checksum);
write(w, digest);
w.close().get();
}
future<index_list> sstable::read_indexes(uint64_t position, uint64_t quantity) {
struct reader {
uint64_t count = 0;
std::vector<index_entry> indexes;
shared_file_random_access_reader stream;
reader(file f, uint64_t quantity) : stream(f) { indexes.reserve(quantity); }
};
auto r = make_lw_shared<reader>(_index_file, quantity);
r->stream.seek(position);
auto end = [r, quantity] { return r->count >= quantity; };
return do_until(end, [this, r] {
r->indexes.emplace_back();
auto fut = parse(r->stream, r->indexes.back());
return std::move(fut).then_wrapped([this, r] (future<> f) mutable {
try {
f.get();
r->count++;
} catch (bufsize_mismatch_exception &e) {
// We have optimistically emplaced back one element of the
// vector. If we have failed to parse, we should remove it
// so size() gives us the right picture.
r->indexes.pop_back();
// FIXME: If the file ends at an index boundary, there is
// no problem. Essentially, we can't know how many indexes
// are in a sampling group, so there isn't really any way
// to know, other than reading.
//
// If, however, we end in the middle of an index, this is a
// corrupted file. This code is not perfect because we only
// know that an exception happened, and it happened due to
// eof. We don't really know if eof happened at the index
// boundary. To know that, we would have to keep track of
// the real position of the stream (including what's
// already in the buffer) before we start to read the
// index, and after. We won't go through such complexity at
// the moment.
if (r->stream.eof()) {
r->count = std::numeric_limits<std::remove_reference<decltype(r->count)>::type>::max();
} else {
throw e;
}
}
return make_ready_future<>();
});
}).then([r] {
return make_ready_future<index_list>(std::move(r->indexes));
});
}
template <sstable::component_type Type, typename T>
future<> sstable::read_simple(T& component) {
auto file_path = filename(Type);
sstlog.debug(("Reading " + _component_map[Type] + " file {} ").c_str(), file_path);
return engine().open_file_dma(file_path, open_flags::ro).then([this, &component] (file f) {
auto r = std::make_unique<file_random_access_reader>(std::move(f), 4096);
auto fut = parse(*r, component);
return fut.then([r = std::move(r)] {});
}).then_wrapped([this, file_path] (future<> f) {
try {
f.get();
} catch (std::system_error& e) {
if (e.code() == std::error_code(ENOENT, std::system_category())) {
throw malformed_sstable_exception(file_path + ": file not found");
}
}
});
}
template <sstable::component_type Type, typename T>
void sstable::write_simple(T& component) {
auto file_path = filename(Type);
sstlog.debug(("Writing " + _component_map[Type] + " file {} ").c_str(), file_path);
file f = engine().open_file_dma(file_path, open_flags::wo | open_flags::create | open_flags::truncate).get0();
auto out = file_writer(std::move(f), 4096);
auto w = file_writer(std::move(out));
write(w, component);
w.flush().get();
w.close().get();
}
template future<> sstable::read_simple<sstable::component_type::Filter>(sstables::filter& f);
template void sstable::write_simple<sstable::component_type::Filter>(sstables::filter& f);
future<> sstable::read_compression() {
// FIXME: If there is no compression, we should expect a CRC file to be present.
if (!has_component(sstable::component_type::CompressionInfo)) {
return make_ready_future<>();
}
return read_simple<component_type::CompressionInfo>(_compression);
}
void sstable::write_compression() {
if (!has_component(sstable::component_type::CompressionInfo)) {
return;
}
write_simple<component_type::CompressionInfo>(_compression);
}
future<> sstable::read_statistics() {
return read_simple<component_type::Statistics>(_statistics);
}
void sstable::write_statistics() {
write_simple<component_type::Statistics>(_statistics);
}
future<> sstable::open_data() {
return when_all(engine().open_file_dma(filename(component_type::Index), open_flags::ro),
engine().open_file_dma(filename(component_type::Data), open_flags::ro)).then([this] (auto files) {
_index_file = std::get<file>(std::get<0>(files).get());
_data_file = std::get<file>(std::get<1>(files).get());
return _data_file.size().then([this] (auto size) {
_data_file_size = size;
});
});
}
future<> sstable::create_data() {
auto oflags = open_flags::wo | open_flags::create | open_flags::exclusive;
return when_all(engine().open_file_dma(filename(component_type::Index), oflags),
engine().open_file_dma(filename(component_type::Data), oflags)).then([this] (auto files) {
// FIXME: If both files could not be created, the first get below will
// throw an exception, and second get() will not be attempted, and
// we'll get a warning about the second future being destructed
// without its exception being examined.
_index_file = std::get<file>(std::get<0>(files).get());
_data_file = std::get<file>(std::get<1>(files).get());
});
}
future<> sstable::load() {
return read_toc().then([this] {
return read_statistics();
}).then([this] {
return read_compression();
}).then([this] {
return read_filter();
}).then([this] {;
return read_summary();
}).then([this] {
return open_data();
}).then([this] {
// After we have _compression and _data_file_size, we can update
// _compression with additional information it needs:
if (has_component(sstable::component_type::CompressionInfo)) {
_compression.update(_data_file_size);
}
});
}
future<> sstable::store() {
// TODO: write other components as well.
return seastar::async([this] {
write_statistics();
write_compression();
write_filter();
write_summary();
});
}
// @clustering_key: it's expected that clustering key is already in its composite form.
// NOTE: empty clustering key means that there is no clustering key.
void sstable::write_column_name(file_writer& out, const composite& clustering_key, const std::vector<bytes_view>& column_names, composite_marker m) {
// FIXME: min_components and max_components also keep track of clustering
// prefix, so we must merge clustering_key and column_names somehow and
// pass the result to the functions below.
column_name_helper::min_components(_c_stats.min_column_names, column_names);
column_name_helper::max_components(_c_stats.max_column_names, column_names);
// was defined in the schema, for example.
auto c= composite::from_exploded(column_names, m);
auto ck_bview = bytes_view(clustering_key);
// The marker is not a component, so if the last component is empty (IOW,
// only serializes to the marker), then we just replace the key's last byte
// with the marker. If the component however it is not empty, then the
// marker should be in the end of it, and we just join them together as we
// do for any normal component
if (c.size() == 1) {
ck_bview.remove_suffix(1);
}
uint16_t sz = ck_bview.size() + c.size();
write(out, sz, ck_bview, c);
}
void sstable::write_column_name(file_writer& out, bytes_view column_names) {
column_name_helper::min_components(_c_stats.min_column_names, { column_names });
column_name_helper::max_components(_c_stats.max_column_names, { column_names });
uint16_t sz = column_names.size();
write(out, sz, column_names);
}
static inline void update_cell_stats(column_stats& c_stats, uint64_t timestamp) {
c_stats.update_min_timestamp(timestamp);
c_stats.update_max_timestamp(timestamp);
c_stats.column_count++;
}
// Intended to write all cell components that follow column name.
void sstable::write_cell(file_writer& out, atomic_cell_view cell) {
// FIXME: range tombstone and counter cells aren't supported yet.
uint64_t timestamp = cell.timestamp();
update_cell_stats(_c_stats, timestamp);
if (cell.is_dead(_now)) {
// tombstone cell
column_mask mask = column_mask::deletion;
uint32_t deletion_time_size = sizeof(uint32_t);
uint32_t deletion_time = cell.deletion_time().time_since_epoch().count();
_c_stats.tombstone_histogram.update(deletion_time);
write(out, mask, timestamp, deletion_time_size, deletion_time);
} else if (cell.is_live_and_has_ttl()) {
// expiring cell
column_mask mask = column_mask::expiration;
uint32_t ttl = cell.ttl().count();
uint32_t expiration = cell.expiry().time_since_epoch().count();
disk_string_view<uint32_t> cell_value { cell.value() };
write(out, mask, ttl, expiration, timestamp, cell_value);
} else {
// regular cell
column_mask mask = column_mask::none;
disk_string_view<uint32_t> cell_value { cell.value() };
write(out, mask, timestamp, cell_value);
}
}
void sstable::write_row_marker(file_writer& out, const rows_entry& clustered_row, const composite& clustering_key) {
const auto& marker = clustered_row.row().marker();
if (marker.is_missing()) {
return;
}
// Write row mark cell to the beginning of clustered row.
write_column_name(out, clustering_key, { bytes_view() });
uint64_t timestamp = marker.timestamp();
uint32_t value_length = 0;
update_cell_stats(_c_stats, timestamp);
if (marker.is_dead(_now)) {
column_mask mask = column_mask::deletion;
uint32_t deletion_time_size = sizeof(uint32_t);
uint32_t deletion_time = marker.deletion_time().time_since_epoch().count();
_c_stats.tombstone_histogram.update(deletion_time);
write(out, mask, timestamp, deletion_time_size, deletion_time);
} else if (marker.is_expiring()) {
column_mask mask = column_mask::expiration;
uint32_t ttl = marker.ttl().count();
uint32_t expiration = marker.expiry().time_since_epoch().count();
write(out, mask, ttl, expiration, timestamp, value_length);
} else {
column_mask mask = column_mask::none;
write(out, mask, timestamp, value_length);
}
}
void sstable::write_range_tombstone(file_writer& out, const composite& clustering_prefix, std::vector<bytes_view> suffix, const tombstone t) {
if (!t) {
return;
}
write_column_name(out, clustering_prefix, suffix, composite_marker::start_range);
column_mask mask = column_mask::range_tombstone;
write(out, mask);
write_column_name(out, clustering_prefix, suffix, composite_marker::end_range);
uint64_t timestamp = t.timestamp;
uint32_t deletion_time = t.deletion_time.time_since_epoch().count();
update_cell_stats(_c_stats, timestamp);
_c_stats.tombstone_histogram.update(deletion_time);
write(out, deletion_time, timestamp);
}
void sstable::write_collection(file_writer& out, const composite& clustering_key, const column_definition& cdef, collection_mutation::view collection) {
auto t = static_pointer_cast<const collection_type_impl>(cdef.type);
auto mview = t->deserialize_mutation_form(collection);
const bytes& column_name = cdef.name();
write_range_tombstone(out, clustering_key, { bytes_view(column_name) }, mview.tomb);
for (auto& cp: mview.cells) {
write_column_name(out, clustering_key, { column_name, cp.first });
write_cell(out, cp.second);
}
}
// write_datafile_clustered_row() is about writing a clustered_row to data file according to SSTables format.
// clustered_row contains a set of cells sharing the same clustering key.
void sstable::write_clustered_row(file_writer& out, const schema& schema, const rows_entry& clustered_row) {
auto clustering_key = composite::from_clustering_element(schema, clustered_row.key());
if (schema.is_compound() && !schema.is_dense()) {
write_row_marker(out, clustered_row, clustering_key);
}
// FIXME: Before writing cells, range tombstone must be written if the row has any (deletable_row::t).
assert(!clustered_row.row().deleted_at());
// Write all cells of a partition's row.
for (auto& value: clustered_row.row().cells()) {
auto column_id = value.first;
auto&& column_definition = schema.regular_column_at(column_id);
// non atomic cell isn't supported yet. atomic cell maps to a single trift cell.
// non atomic cell maps to multiple trift cell, e.g. collection.
if (!column_definition.is_atomic()) {
write_collection(out, clustering_key, column_definition, value.second.as_collection_mutation());
return;
}
assert(column_definition.is_regular());
atomic_cell_view cell = value.second.as_atomic_cell();
const bytes& column_name = column_definition.name();
if (schema.is_compound()) {
if (schema.is_dense()) {
write_column_name(out, bytes_view(clustering_key));
} else {
write_column_name(out, clustering_key, { bytes_view(column_name) });
}
} else {
if (schema.is_dense()) {
write_column_name(out, bytes_view(clustered_row.key()));
} else {
write_column_name(out, bytes_view(column_name));
}
}
write_cell(out, cell);
}
}
void sstable::write_static_row(file_writer& out, const schema& schema, const row& static_row) {
for (auto& value: static_row) {
auto column_id = value.first;
auto&& column_definition = schema.static_column_at(column_id);
if (!column_definition.is_atomic()) {
auto sp = composite::static_prefix(schema);
write_collection(out, sp, column_definition, value.second.as_collection_mutation());
return;
}
assert(column_definition.is_static());
atomic_cell_view cell = value.second.as_atomic_cell();
auto sp = composite::static_prefix(schema);
write_column_name(out, sp, { bytes_view(column_definition.name()) });
write_cell(out, cell);
}
}
static void write_index_entry(file_writer& out, disk_string_view<uint16_t>& key, uint64_t pos) {
// FIXME: support promoted indexes.
uint32_t promoted_index_size = 0;
write(out, key, pos, promoted_index_size);
}
static constexpr int BASE_SAMPLING_LEVEL = 128;
static void prepare_summary(summary& s, uint64_t expected_partition_count) {
assert(expected_partition_count >= 1);
s.header.min_index_interval = BASE_SAMPLING_LEVEL;
s.header.sampling_level = BASE_SAMPLING_LEVEL;
uint64_t max_expected_entries =
(expected_partition_count / BASE_SAMPLING_LEVEL) +
!!(expected_partition_count % BASE_SAMPLING_LEVEL);
// FIXME: handle case where max_expected_entries is greater than max value stored by uint32_t.
if (max_expected_entries > std::numeric_limits<uint32_t>::max()) {
throw malformed_sstable_exception("Current sampling level (" + to_sstring(BASE_SAMPLING_LEVEL) + ") not enough to generate summary.");
}
s.positions.reserve(max_expected_entries);
s.entries.reserve(max_expected_entries);
s.keys_written = 0;
s.header.memory_size = 0;
}
static void seal_summary(summary& s,
std::experimental::optional<key>&& first_key,
std::experimental::optional<key>&& last_key,
const schema& schema) {
s.header.size = s.entries.size();
s.header.size_at_full_sampling = s.header.size;
s.header.memory_size = s.header.size * sizeof(uint32_t);
for (auto& e: s.entries) {
s.positions.push_back(s.header.memory_size);
s.header.memory_size += e.key.size() + sizeof(e.position);
}
assert(first_key); // assume non-empty sstable
s.first_key.value = first_key->get_bytes();
if (last_key) {
s.last_key.value = last_key->get_bytes();
} else {
// An empty last_mutation indicates we had just one partition
s.last_key.value = s.first_key.value;
}
}
static void prepare_compression(compression& c, const schema& schema) {
const auto& cp = schema.get_compressor_params();
c.set_compressor(cp.get_compressor());
c.chunk_len = cp.chunk_length();
c.data_len = 0;
// FIXME: crc_check_chance can be configured by the user.
// probability to verify the checksum of a compressed chunk we read.
// defaults to 1.0.
c.options.elements.push_back({"crc_check_chance", "1.0"});
c.init_full_checksum();
}
static void maybe_add_summary_entry(summary& s, bytes_view key, uint64_t offset) {
// Maybe add summary entry into in-memory representation of summary file.
if ((s.keys_written++ % s.header.min_index_interval) == 0) {
s.entries.push_back({ bytes(key.data(), key.size()), offset });
}
}
// In the beginning of the statistics file, there is a disk_hash used to
// map each metadata type to its correspondent position in the file.
static void seal_statistics(statistics& s, metadata_collector& collector,
const sstring partitioner, double bloom_filter_fp_chance) {
static constexpr int METADATA_TYPE_COUNT = 3;
size_t old_offset, offset = 0;
// account disk_hash size.
offset += sizeof(uint32_t);
// account disk_hash members.
offset += (METADATA_TYPE_COUNT * (sizeof(metadata_type) + sizeof(uint32_t)));
validation_metadata validation;
compaction_metadata compaction;
stats_metadata stats;
old_offset = offset;
validation.partitioner.value = to_bytes(partitioner);
validation.filter_chance = bloom_filter_fp_chance;
offset += validation.serialized_size();
s.contents[metadata_type::Validation] = std::make_unique<validation_metadata>(std::move(validation));
s.hash.map[metadata_type::Validation] = old_offset;
old_offset = offset;
collector.construct_compaction(compaction);
offset += compaction.serialized_size();
s.contents[metadata_type::Compaction] = std::make_unique<compaction_metadata>(std::move(compaction));
s.hash.map[metadata_type::Compaction] = old_offset;
collector.construct_stats(stats);
// NOTE: method serialized_size of stats_metadata must be implemented for
// a new type of compaction to get supported.
s.contents[metadata_type::Stats] = std::make_unique<stats_metadata>(std::move(stats));
s.hash.map[metadata_type::Stats] = offset;
}
static constexpr size_t sstable_buffer_size = 64*1024;
///
/// @param out holds an output stream to data file.
///
void sstable::do_write_components(::mutation_reader mr,
uint64_t estimated_partitions, schema_ptr schema, file_writer& out) {
auto index = make_shared<file_writer>(_index_file, sstable_buffer_size);
auto filter_fp_chance = schema->bloom_filter_fp_chance();
if (filter_fp_chance != 1.0) {
_components.insert(component_type::Filter);
}
_filter = utils::i_filter::get_filter(estimated_partitions, filter_fp_chance);
prepare_summary(_summary, estimated_partitions);
// FIXME: it's likely that we need to set both sstable_level and repaired_at stats at this point.
// Remember first and last keys, which we need for the summary file.
std::experimental::optional<key> first_key, last_key;
// Iterate through CQL partitions, then CQL rows, then CQL columns.
// Each mt.all_partitions() entry is a set of clustered rows sharing the same partition key.
while (mutation_opt mut = mr().get0()) {
// Set current index of data to later compute row size.
_c_stats.start_offset = out.offset();
auto partition_key = key::from_partition_key(*schema, mut->key());
maybe_add_summary_entry(_summary, bytes_view(partition_key), index->offset());
_filter->add(bytes_view(partition_key));
_collector.add_key(bytes_view(partition_key));
auto p_key = disk_string_view<uint16_t>();
p_key.value = bytes_view(partition_key);
// Write index file entry from partition key into index file.
write_index_entry(*index, p_key, out.offset());
// Write partition key into data file.
write(out, p_key);
auto tombstone = mut->partition().partition_tombstone();
deletion_time d;
if (tombstone) {
d.local_deletion_time = tombstone.deletion_time.time_since_epoch().count();
d.marked_for_delete_at = tombstone.timestamp;
_c_stats.tombstone_histogram.update(d.local_deletion_time);
_c_stats.update_max_local_deletion_time(d.local_deletion_time);
_c_stats.update_min_timestamp(d.marked_for_delete_at);
_c_stats.update_max_timestamp(d.marked_for_delete_at);
} else {
// Default values for live, undeleted rows.
d.local_deletion_time = std::numeric_limits<int32_t>::max();
d.marked_for_delete_at = std::numeric_limits<int64_t>::min();
}
write(out, d);
auto& partition = mut->partition();
auto& static_row = partition.static_row();
write_static_row(out, *schema, static_row);
for (const auto& rt: partition.row_tombstones()) {
auto prefix = composite::from_clustering_element(*schema, rt.prefix());
write_range_tombstone(out, prefix, {}, rt.t());
}
// Write all CQL rows from a given mutation partition.
for (auto& clustered_row: partition.clustered_rows()) {
write_clustered_row(out, *schema, clustered_row);
}
int16_t end_of_row = 0;
write(out, end_of_row);
// compute size of the current row.
_c_stats.row_size = out.offset() - _c_stats.start_offset;
// update is about merging column_stats with the data being stored by collector.
_collector.update(std::move(_c_stats));
_c_stats.reset();
if (!first_key) {
first_key = std::move(partition_key);
} else {
last_key = std::move(partition_key);
}
}
seal_summary(_summary, std::move(first_key), std::move(last_key), *schema);
index->close().get();
_index_file = file(); // index->close() closed _index_file
_components.insert(component_type::TOC);
_components.insert(component_type::Statistics);
_components.insert(component_type::Digest);
_components.insert(component_type::Index);
_components.insert(component_type::Summary);
_components.insert(component_type::Data);
if (has_component(sstable::component_type::CompressionInfo)) {
_collector.add_compression_ratio(_compression.compressed_file_length(), _compression.uncompressed_file_length());
}
// NOTE: Cassandra gets partition name by calling getClass().getCanonicalName() on
// partition class.
seal_statistics(_statistics, _collector, dht::global_partitioner().name(), filter_fp_chance);
}
void sstable::prepare_write_components(::mutation_reader mr, uint64_t estimated_partitions, schema_ptr schema) {
// CRC component must only be present when compression isn't enabled.
bool checksum_file = schema->get_compressor_params().get_compressor() == compressor::none;
if (checksum_file) {
auto w = make_shared<checksummed_file_writer>(_data_file, sstable_buffer_size, checksum_file);
_components.insert(component_type::CRC);
this->do_write_components(std::move(mr), estimated_partitions, std::move(schema), *w);
w->close().get();
_data_file = file(); // w->close() closed _data_file
write_digest(filename(sstable::component_type::Digest), w->full_checksum());
write_crc(filename(sstable::component_type::CRC), w->finalize_checksum());
} else {
prepare_compression(_compression, *schema);
auto w = make_shared<file_writer>(make_compressed_file_output_stream(_data_file, &_compression));
_components.insert(component_type::CompressionInfo);
this->do_write_components(std::move(mr), estimated_partitions, std::move(schema), *w);
w->close().get();
_data_file = file(); // w->close() closed _data_file
write_digest(filename(sstable::component_type::Digest), _compression.full_checksum());
}
}
future<> sstable::write_components(const memtable& mt) {
return write_components(mt.make_reader(),
mt.all_partitions().size(), mt.schema());
}
future<> sstable::write_components(::mutation_reader mr,
uint64_t estimated_partitions, schema_ptr schema) {
return seastar::async([this, mr = std::move(mr), estimated_partitions, schema = std::move(schema)] {
touch_directory(_dir).get();
create_data().get();
prepare_write_components(std::move(mr), estimated_partitions, std::move(schema));
write_summary();
write_filter();
write_statistics();
// NOTE: write_compression means maybe_write_compression.
write_compression();
write_toc();
});
}
uint64_t sstable::data_size() {
if (has_component(sstable::component_type::CompressionInfo)) {
return _compression.data_len;
}
return _data_file_size;
}
future<uint64_t> sstable::bytes_on_disk() {
if (_bytes_on_disk) {
return make_ready_future<uint64_t>(_bytes_on_disk);
}
return do_for_each(_components, [this] (component_type c) {
return engine().file_size(filename(c)).then([this] (uint64_t bytes) {
_bytes_on_disk += bytes;
});
}).then([this] {
return make_ready_future<uint64_t>(_bytes_on_disk);
});
}
const bool sstable::has_component(component_type f) {
return _components.count(f);
}
const sstring sstable::filename(component_type f) {
auto& version = _version_string.at(_version);
auto& format = _format_string.at(_format);
auto& component = _component_map.at(f);
auto generation = to_sstring(_generation);
return _dir + "/" + version + "-" + generation + "-" + format + "-" + component;
}
const sstring sstable::filename(sstring dir, version_types version, unsigned long generation,
format_types format, component_type component) {
auto& v = _version_string.at(version);
auto& f = _format_string.at(format);
auto& c= _component_map.at(component);
auto g = to_sstring(generation);
return dir + "/" + v + "-" + g + "-" + f + "-" + c;
}
sstable::version_types sstable::version_from_sstring(sstring &s) {
return reverse_map(s, _version_string);
}
sstable::format_types sstable::format_from_sstring(sstring &s) {
return reverse_map(s, _format_string);
}
input_stream<char> sstable::data_stream_at(uint64_t pos) {
if (_compression) {
return make_compressed_file_input_stream(
_data_file, &_compression, pos);
} else {
return make_file_input_stream(_data_file, pos);
}
}
// FIXME: to read a specific byte range, we shouldn't use the input stream
// interface - it may cause too much read when we intend to read a small
// range, and too small reads, and repeated waits, when reading a large range
// which we should have started at once.
future<temporary_buffer<char>> sstable::data_read(uint64_t pos, size_t len) {
return do_with(data_stream_at(pos), [len] (auto& stream) {
return stream.read_exactly(len);
});
}
partition_key
sstable::get_first_partition_key(const schema& s) const {
return key::from_bytes(_summary.first_key.value).to_partition_key(s);
}
partition_key
sstable::get_last_partition_key(const schema& s) const {
return key::from_bytes(_summary.last_key.value).to_partition_key(s);
}
sstable::~sstable() {
if (_index_file) {
_index_file.close().handle_exception([save = _index_file] (auto ep) {
sstlog.warn("sstable close index_file failed: {}", ep);
});
}
if (_data_file) {
_data_file.close().handle_exception([save = _data_file] (auto ep) {
sstlog.warn("sstable close data_file failed: {}", ep);
});
}
if (_marked_for_deletion) {
// We need to delete the on-disk files for this table. Since this is a
// destructor, we can't wait for this to finish, or return any errors,
// but just need to do our best. If a deletion fails for some reason we
// log and ignore this failure, because on startup we'll again try to
// clean up unused sstables, and because we'll never reuse the same
// generation number anyway.
try {
for (auto component : _components) {
remove_file(filename(component)).handle_exception(
[] (std::exception_ptr eptr) {
sstlog.warn("Exception when deleting sstable file: {}", eptr);
});
}
} catch (...) {
sstlog.warn("Exception when deleting sstable file: {}", std::current_exception());
}
}
}
}