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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/compacted_db_impl.h"
#include "db/db_impl/db_impl.h"
#include "db/db_iter.h"
#include "db/merge_context.h"
#include "monitoring/perf_context_imp.h"
namespace ROCKSDB_NAMESPACE {
#ifndef ROCKSDB_LITE
DBImplReadOnly::DBImplReadOnly(const DBOptions& db_options,
const std::string& dbname)
: DBImpl(db_options, dbname) {
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) {
assert(pinnable_val != nullptr);
// TODO: stopwatch DB_GET needed?, perf timer needed?
PERF_TIMER_GUARD(get_snapshot_time);
Status s;
SequenceNumber snapshot = versions_->LastSequence();
auto cfh = reinterpret_cast<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);
PERF_TIMER_STOP(get_snapshot_time);
if (super_version->mem->Get(lkey, pinnable_val->GetSelf(), &s, &merge_context,
&max_covering_tombstone_seq, read_options)) {
pinnable_val->PinSelf();
RecordTick(stats_, MEMTABLE_HIT);
} else {
PERF_TIMER_GUARD(get_from_output_files_time);
super_version->current->Get(read_options, lkey, pinnable_val, &s,
&merge_context, &max_covering_tombstone_seq);
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) {
auto cfh = reinterpret_cast<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,
read_seq,
super_version->mutable_cf_options.max_sequential_skip_in_iterations,
super_version->version_number, read_callback);
auto internal_iter =
NewInternalIterator(read_options, cfd, super_version, db_iter->GetArena(),
db_iter->GetRangeDelAggregator(), read_seq);
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) {
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 = reinterpret_cast<ColumnFamilyHandleImpl*>(cfh)->cfd();
auto* sv = cfd->GetSuperVersion()->Ref();
auto* db_iter = NewArenaWrappedDbIterator(
env_, read_options, *cfd->ioptions(), sv->mutable_cf_options, read_seq,
sv->mutable_cf_options.max_sequential_skip_in_iterations,
sv->version_number, read_callback);
auto* internal_iter =
NewInternalIterator(read_options, cfd, sv, db_iter->GetArena(),
db_iter->GetRangeDelAggregator(), read_seq);
db_iter->SetIterUnderDBIter(internal_iter);
iterators->push_back(db_iter);
}
return Status::OK();
}
Status DB::OpenForReadOnly(const Options& options, const std::string& dbname,
DB** dbptr, bool /*error_if_log_file_exist*/) {
*dbptr = nullptr;
// Try to first open DB as fully compacted DB
Status s;
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 = DB::OpenForReadOnly(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_log_file_exist) {
*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_log_file_exist);
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(
reinterpret_cast<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_log_file_exist*/) {
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_log_file_exist*/) {
return Status::NotSupported("Not supported in ROCKSDB_LITE.");
}
#endif // !ROCKSDB_LITE
} // namespace ROCKSDB_NAMESPACE
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