1 files changed, 210 insertions, 0 deletions
diff --git a/src/rocksdb/table/iterator.cc b/src/rocksdb/table/iterator.cc
new file mode 100644
index 000000000..4ecfc007b
--- /dev/null
+++ b/src/rocksdb/table/iterator.cc
@@ -0,0 +1,210 @@
+//  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).
+//
+// Copyright (c) 2011 The LevelDB Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file. See the AUTHORS file for names of contributors.
+
+#include "rocksdb/iterator.h"
+#include "memory/arena.h"
+#include "table/internal_iterator.h"
+#include "table/iterator_wrapper.h"
+
+namespace ROCKSDB_NAMESPACE {
+
+Cleanable::Cleanable() {
+  cleanup_.function = nullptr;
+  cleanup_.next = nullptr;
+}
+
+Cleanable::~Cleanable() { DoCleanup(); }
+
+Cleanable::Cleanable(Cleanable&& other) {
+  *this = std::move(other);
+}
+
+Cleanable& Cleanable::operator=(Cleanable&& other) {
+  if (this != &other) {
+    cleanup_ = other.cleanup_;
+    other.cleanup_.function = nullptr;
+    other.cleanup_.next = nullptr;
+  }
+  return *this;
+}
+
+// If the entire linked list was on heap we could have simply add attach one
+// link list to another. However the head is an embeded object to avoid the cost
+// of creating objects for most of the use cases when the Cleanable has only one
+// Cleanup to do. We could put evernything on heap if benchmarks show no
+// negative impact on performance.
+// Also we need to iterate on the linked list since there is no pointer to the
+// tail. We can add the tail pointer but maintainin it might negatively impact
+// the perforamnce for the common case of one cleanup where tail pointer is not
+// needed. Again benchmarks could clarify that.
+// Even without a tail pointer we could iterate on the list, find the tail, and
+// have only that node updated without the need to insert the Cleanups one by
+// one. This however would be redundant when the source Cleanable has one or a
+// few Cleanups which is the case most of the time.
+// TODO(myabandeh): if the list is too long we should maintain a tail pointer
+// and have the entire list (minus the head that has to be inserted separately)
+// merged with the target linked list at once.
+void Cleanable::DelegateCleanupsTo(Cleanable* other) {
+  assert(other != nullptr);
+  if (cleanup_.function == nullptr) {
+    return;
+  }
+  Cleanup* c = &cleanup_;
+  other->RegisterCleanup(c->function, c->arg1, c->arg2);
+  c = c->next;
+  while (c != nullptr) {
+    Cleanup* next = c->next;
+    other->RegisterCleanup(c);
+    c = next;
+  }
+  cleanup_.function = nullptr;
+  cleanup_.next = nullptr;
+}
+
+void Cleanable::RegisterCleanup(Cleanable::Cleanup* c) {
+  assert(c != nullptr);
+  if (cleanup_.function == nullptr) {
+    cleanup_.function = c->function;
+    cleanup_.arg1 = c->arg1;
+    cleanup_.arg2 = c->arg2;
+    delete c;
+  } else {
+    c->next = cleanup_.next;
+    cleanup_.next = c;
+  }
+}
+
+void Cleanable::RegisterCleanup(CleanupFunction func, void* arg1, void* arg2) {
+  assert(func != nullptr);
+  Cleanup* c;
+  if (cleanup_.function == nullptr) {
+    c = &cleanup_;
+  } else {
+    c = new Cleanup;
+    c->next = cleanup_.next;
+    cleanup_.next = c;
+  }
+  c->function = func;
+  c->arg1 = arg1;
+  c->arg2 = arg2;
+}
+
+Status Iterator::GetProperty(std::string prop_name, std::string* prop) {
+  if (prop == nullptr) {
+    return Status::InvalidArgument("prop is nullptr");
+  }
+  if (prop_name == "rocksdb.iterator.is-key-pinned") {
+    *prop = "0";
+    return Status::OK();
+  }
+  return Status::InvalidArgument("Unidentified property.");
+}
+
+namespace {
+class EmptyIterator : public Iterator {
+ public:
+  explicit EmptyIterator(const Status& s) : status_(s) { }
+  bool Valid() const override { return false; }
+  void Seek(const Slice& /*target*/) override {}
+  void SeekForPrev(const Slice& /*target*/) override {}
+  void SeekToFirst() override {}
+  void SeekToLast() override {}
+  void Next() override { assert(false); }
+  void Prev() override { assert(false); }
+  Slice key() const override {
+    assert(false);
+    return Slice();
+  }
+  Slice value() const override {
+    assert(false);
+    return Slice();
+  }
+  Status status() const override { return status_; }
+
+ private:
+  Status status_;
+};
+
+template <class TValue = Slice>
+class EmptyInternalIterator : public InternalIteratorBase<TValue> {
+ public:
+  explicit EmptyInternalIterator(const Status& s) : status_(s) {}
+  bool Valid() const override { return false; }
+  void Seek(const Slice& /*target*/) override {}
+  void SeekForPrev(const Slice& /*target*/) override {}
+  void SeekToFirst() override {}
+  void SeekToLast() override {}
+  void Next() override { assert(false); }
+  void Prev() override { assert(false); }
+  Slice key() const override {
+    assert(false);
+    return Slice();
+  }
+  TValue value() const override {
+    assert(false);
+    return TValue();
+  }
+  Status status() const override { return status_; }
+
+ private:
+  Status status_;
+};
+}  // namespace
+
+Iterator* NewEmptyIterator() { return new EmptyIterator(Status::OK()); }
+
+Iterator* NewErrorIterator(const Status& status) {
+  return new EmptyIterator(status);
+}
+
+template <class TValue>
+InternalIteratorBase<TValue>* NewErrorInternalIterator(const Status& status) {
+  return new EmptyInternalIterator<TValue>(status);
+}
+template InternalIteratorBase<IndexValue>* NewErrorInternalIterator(
+    const Status& status);
+template InternalIteratorBase<Slice>* NewErrorInternalIterator(
+    const Status& status);
+
+template <class TValue>
+InternalIteratorBase<TValue>* NewErrorInternalIterator(const Status& status,
+                                                       Arena* arena) {
+  if (arena == nullptr) {
+    return NewErrorInternalIterator<TValue>(status);
+  } else {
+    auto mem = arena->AllocateAligned(sizeof(EmptyInternalIterator<TValue>));
+    return new (mem) EmptyInternalIterator<TValue>(status);
+  }
+}
+template InternalIteratorBase<IndexValue>* NewErrorInternalIterator(
+    const Status& status, Arena* arena);
+template InternalIteratorBase<Slice>* NewErrorInternalIterator(
+    const Status& status, Arena* arena);
+
+template <class TValue>
+InternalIteratorBase<TValue>* NewEmptyInternalIterator() {
+  return new EmptyInternalIterator<TValue>(Status::OK());
+}
+template InternalIteratorBase<IndexValue>* NewEmptyInternalIterator();
+template InternalIteratorBase<Slice>* NewEmptyInternalIterator();
+
+template <class TValue>
+InternalIteratorBase<TValue>* NewEmptyInternalIterator(Arena* arena) {
+  if (arena == nullptr) {
+    return NewEmptyInternalIterator<TValue>();
+  } else {
+    auto mem = arena->AllocateAligned(sizeof(EmptyInternalIterator<TValue>));
+    return new (mem) EmptyInternalIterator<TValue>(Status::OK());
+  }
+}
+template InternalIteratorBase<IndexValue>* NewEmptyInternalIterator(
+    Arena* arena);
+template InternalIteratorBase<Slice>* NewEmptyInternalIterator(Arena* arena);
+
+}  // namespace ROCKSDB_NAMESPACE