1 files changed, 220 insertions, 0 deletions
diff --git a/src/rocksdb/db/db_impl_readonly.cc b/src/rocksdb/db/db_impl_readonly.cc
new file mode 100644
index 00000000..5d7515c2
--- /dev/null
+++ b/src/rocksdb/db/db_impl_readonly.cc
@@ -0,0 +1,220 @@
+//  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_readonly.h"
+
+#include "db/compacted_db_impl.h"
+#include "db/db_impl.h"
+#include "db/db_iter.h"
+#include "db/merge_context.h"
+#include "monitoring/perf_context_imp.h"
+
+namespace rocksdb {
+
+#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