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rocksdb/db/db_impl/db_impl_readonly.cc

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// Copyright (c) 2011-present, Facebook, Inc. All rights reserved.
// This source code is licensed under both the GPLv2 (found in the
// COPYING file in the root directory) and Apache 2.0 License
// (found in the LICENSE.Apache file in the root directory).
#include "db/db_impl/db_impl_readonly.h"
#include "db/arena_wrapped_db_iter.h"
#include "db/db_impl/compacted_db_impl.h"
#include "db/db_impl/db_impl.h"
#include "db/db_iter.h"
#include "db/merge_context.h"
#include "logging/logging.h"
#include "monitoring/perf_context_imp.h"
#include "util/cast_util.h"
namespace ROCKSDB_NAMESPACE {
#ifndef ROCKSDB_LITE
DBImplReadOnly::DBImplReadOnly(const DBOptions& db_options,
const std::string& dbname)
: DBImpl(db_options, dbname, /*seq_per_batch*/ false,
/*batch_per_txn*/ true, /*read_only*/ true) {
ROCKS_LOG_INFO(immutable_db_options_.info_log,
"Opening the db in read only mode");
LogFlush(immutable_db_options_.info_log);
}
DBImplReadOnly::~DBImplReadOnly() {}
// Implementations of the DB interface
Status DBImplReadOnly::Get(const ReadOptions& read_options,
ColumnFamilyHandle* column_family, const Slice& key,
PinnableSlice* pinnable_val) {
return Get(read_options, column_family, key, pinnable_val,
/*timestamp*/ nullptr);
}
Status DBImplReadOnly::Get(const ReadOptions& read_options,
ColumnFamilyHandle* column_family, const Slice& key,
PinnableSlice* pinnable_val,
std::string* timestamp) {
assert(pinnable_val != nullptr);
// TODO: stopwatch DB_GET needed?, perf timer needed?
PERF_TIMER_GUARD(get_snapshot_time);
assert(column_family);
if (read_options.timestamp) {
const Status s = FailIfTsMismatchCf(
column_family, *(read_options.timestamp), /*ts_for_read=*/true);
if (!s.ok()) {
return s;
}
} else {
const Status s = FailIfCfHasTs(column_family);
if (!s.ok()) {
return s;
}
}
// Clear the timestamps for returning results so that we can distinguish
// between tombstone or key that has never been written
if (timestamp) {
timestamp->clear();
}
const Comparator* ucmp = column_family->GetComparator();
assert(ucmp);
std::string* ts = ucmp->timestamp_size() > 0 ? timestamp : nullptr;
Status s;
SequenceNumber snapshot = versions_->LastSequence();
GetWithTimestampReadCallback read_cb(snapshot);
auto cfh = static_cast_with_check<ColumnFamilyHandleImpl>(column_family);
auto cfd = cfh->cfd();
if (tracer_) {
InstrumentedMutexLock lock(&trace_mutex_);
if (tracer_) {
tracer_->Get(column_family, key);
}
}
SuperVersion* super_version = cfd->GetSuperVersion();
MergeContext merge_context;
SequenceNumber max_covering_tombstone_seq = 0;
LookupKey lkey(key, snapshot, read_options.timestamp);
PERF_TIMER_STOP(get_snapshot_time);
if (super_version->mem->Get(lkey, pinnable_val->GetSelf(),
/*columns=*/nullptr, ts, &s, &merge_context,
&max_covering_tombstone_seq, read_options,
false /* immutable_memtable */, &read_cb)) {
pinnable_val->PinSelf();
RecordTick(stats_, MEMTABLE_HIT);
} else {
PERF_TIMER_GUARD(get_from_output_files_time);
PinnedIteratorsManager pinned_iters_mgr;
super_version->current->Get(
read_options, lkey, pinnable_val, /*columns=*/nullptr, ts, &s,
&merge_context, &max_covering_tombstone_seq, &pinned_iters_mgr,
/*value_found*/ nullptr,
/*key_exists*/ nullptr, /*seq*/ nullptr, &read_cb,
/*is_blob*/ nullptr,
/*do_merge*/ true);
RecordTick(stats_, MEMTABLE_MISS);
}
RecordTick(stats_, NUMBER_KEYS_READ);
size_t size = pinnable_val->size();
RecordTick(stats_, BYTES_READ, size);
RecordInHistogram(stats_, BYTES_PER_READ, size);
PERF_COUNTER_ADD(get_read_bytes, size);
return s;
}
Iterator* DBImplReadOnly::NewIterator(const ReadOptions& read_options,
ColumnFamilyHandle* column_family) {
assert(column_family);
if (read_options.timestamp) {
const Status s = FailIfTsMismatchCf(
column_family, *(read_options.timestamp), /*ts_for_read=*/true);
if (!s.ok()) {
return NewErrorIterator(s);
}
} else {
const Status s = FailIfCfHasTs(column_family);
if (!s.ok()) {
return NewErrorIterator(s);
}
}
auto cfh = static_cast_with_check<ColumnFamilyHandleImpl>(column_family);
auto cfd = cfh->cfd();
SuperVersion* super_version = cfd->GetSuperVersion()->Ref();
SequenceNumber latest_snapshot = versions_->LastSequence();
SequenceNumber read_seq =
read_options.snapshot != nullptr
? reinterpret_cast<const SnapshotImpl*>(read_options.snapshot)
->number_
: latest_snapshot;
ReadCallback* read_callback = nullptr; // No read callback provided.
auto db_iter = NewArenaWrappedDbIterator(
env_, read_options, *cfd->ioptions(), super_version->mutable_cf_options,
super_version->current, read_seq,
super_version->mutable_cf_options.max_sequential_skip_in_iterations,
super_version->version_number, read_callback);
auto internal_iter = NewInternalIterator(
db_iter->GetReadOptions(), cfd, super_version, db_iter->GetArena(),
db_iter->GetRangeDelAggregator(), read_seq,
/* allow_unprepared_value */ true);
db_iter->SetIterUnderDBIter(internal_iter);
return db_iter;
}
Status DBImplReadOnly::NewIterators(
const ReadOptions& read_options,
const std::vector<ColumnFamilyHandle*>& column_families,
std::vector<Iterator*>* iterators) {
if (read_options.timestamp) {
for (auto* cf : column_families) {
assert(cf);
const Status s = FailIfTsMismatchCf(cf, *(read_options.timestamp),
/*ts_for_read=*/true);
if (!s.ok()) {
return s;
}
}
} else {
for (auto* cf : column_families) {
assert(cf);
const Status s = FailIfCfHasTs(cf);
if (!s.ok()) {
return s;
}
}
}
ReadCallback* read_callback = nullptr; // No read callback provided.
if (iterators == nullptr) {
return Status::InvalidArgument("iterators not allowed to be nullptr");
}
iterators->clear();
iterators->reserve(column_families.size());
SequenceNumber latest_snapshot = versions_->LastSequence();
SequenceNumber read_seq =
read_options.snapshot != nullptr
? reinterpret_cast<const SnapshotImpl*>(read_options.snapshot)
->number_
: latest_snapshot;
for (auto cfh : column_families) {
auto* cfd = static_cast_with_check<ColumnFamilyHandleImpl>(cfh)->cfd();
auto* sv = cfd->GetSuperVersion()->Ref();
auto* db_iter = NewArenaWrappedDbIterator(
env_, read_options, *cfd->ioptions(), sv->mutable_cf_options,
sv->current, read_seq,
sv->mutable_cf_options.max_sequential_skip_in_iterations,
sv->version_number, read_callback);
auto* internal_iter = NewInternalIterator(
db_iter->GetReadOptions(), cfd, sv, db_iter->GetArena(),
db_iter->GetRangeDelAggregator(), read_seq,
/* allow_unprepared_value */ true);
db_iter->SetIterUnderDBIter(internal_iter);
iterators->push_back(db_iter);
}
return Status::OK();
}
namespace {
// Return OK if dbname exists in the file system or create it if
// create_if_missing
Status OpenForReadOnlyCheckExistence(const DBOptions& db_options,
const std::string& dbname) {
Status s;
if (!db_options.create_if_missing) {
// Attempt to read "CURRENT" file
const std::shared_ptr<FileSystem>& fs = db_options.env->GetFileSystem();
std::string manifest_path;
uint64_t manifest_file_number;
s = VersionSet::GetCurrentManifestPath(dbname, fs.get(), &manifest_path,
&manifest_file_number);
} else {
// Historic behavior that doesn't necessarily make sense
s = db_options.env->CreateDirIfMissing(dbname);
}
return s;
}
} // namespace
Status DB::OpenForReadOnly(const Options& options, const std::string& dbname,
DB** dbptr, bool /*error_if_wal_file_exists*/) {
Status s = OpenForReadOnlyCheckExistence(options, dbname);
if (!s.ok()) {
return s;
}
*dbptr = nullptr;
// Try to first open DB as fully compacted DB
s = CompactedDBImpl::Open(options, dbname, dbptr);
if (s.ok()) {
return s;
}
DBOptions db_options(options);
ColumnFamilyOptions cf_options(options);
std::vector<ColumnFamilyDescriptor> column_families;
column_families.push_back(
ColumnFamilyDescriptor(kDefaultColumnFamilyName, cf_options));
std::vector<ColumnFamilyHandle*> handles;
s = DBImplReadOnly::OpenForReadOnlyWithoutCheck(
db_options, dbname, column_families, &handles, dbptr);
if (s.ok()) {
assert(handles.size() == 1);
// i can delete the handle since DBImpl is always holding a
// reference to default column family
delete handles[0];
}
return s;
}
Status DB::OpenForReadOnly(
const DBOptions& db_options, const std::string& dbname,
const std::vector<ColumnFamilyDescriptor>& column_families,
std::vector<ColumnFamilyHandle*>* handles, DB** dbptr,
bool error_if_wal_file_exists) {
// If dbname does not exist in the file system, should not do anything
Status s = OpenForReadOnlyCheckExistence(db_options, dbname);
if (!s.ok()) {
return s;
}
return DBImplReadOnly::OpenForReadOnlyWithoutCheck(
db_options, dbname, column_families, handles, dbptr,
error_if_wal_file_exists);
}
Status DBImplReadOnly::OpenForReadOnlyWithoutCheck(
const DBOptions& db_options, const std::string& dbname,
const std::vector<ColumnFamilyDescriptor>& column_families,
std::vector<ColumnFamilyHandle*>* handles, DB** dbptr,
bool error_if_wal_file_exists) {
*dbptr = nullptr;
handles->clear();
SuperVersionContext sv_context(/* create_superversion */ true);
DBImplReadOnly* impl = new DBImplReadOnly(db_options, dbname);
impl->mutex_.Lock();
Status s = impl->Recover(column_families, true /* read only */,
error_if_wal_file_exists);
if (s.ok()) {
// set column family handles
for (auto cf : column_families) {
auto cfd =
impl->versions_->GetColumnFamilySet()->GetColumnFamily(cf.name);
if (cfd == nullptr) {
s = Status::InvalidArgument("Column family not found", cf.name);
break;
}
handles->push_back(new ColumnFamilyHandleImpl(cfd, impl, &impl->mutex_));
}
}
if (s.ok()) {
for (auto cfd : *impl->versions_->GetColumnFamilySet()) {
sv_context.NewSuperVersion();
cfd->InstallSuperVersion(&sv_context, &impl->mutex_);
}
}
impl->mutex_.Unlock();
sv_context.Clean();
if (s.ok()) {
*dbptr = impl;
for (auto* h : *handles) {
impl->NewThreadStatusCfInfo(
static_cast_with_check<ColumnFamilyHandleImpl>(h)->cfd());
}
} else {
for (auto h : *handles) {
delete h;
}
handles->clear();
delete impl;
}
return s;
}
#else // !ROCKSDB_LITE
Status DB::OpenForReadOnly(const Options& /*options*/,
const std::string& /*dbname*/, DB** /*dbptr*/,
bool /*error_if_wal_file_exists*/) {
return Status::NotSupported("Not supported in ROCKSDB_LITE.");
}
Status DB::OpenForReadOnly(
const DBOptions& /*db_options*/, const std::string& /*dbname*/,
const std::vector<ColumnFamilyDescriptor>& /*column_families*/,
std::vector<ColumnFamilyHandle*>* /*handles*/, DB** /*dbptr*/,
bool /*error_if_wal_file_exists*/) {
return Status::NotSupported("Not supported in ROCKSDB_LITE.");
}
#endif // !ROCKSDB_LITE
} // namespace ROCKSDB_NAMESPACE