Adding upstream version 18.2.2.upstream/18.2.2

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 129 insertions, 0 deletions

diff --git a/src/rocksdb/file/sequence_file_reader.h b/src/rocksdb/file/sequence_file_reader.h
new file mode 100644
index 000000000..baea10eb7
--- /dev/null
+++ b/src/rocksdb/file/sequence_file_reader.h
@@ -0,0 +1,129 @@
+//  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.
+
+#pragma once
+#include <atomic>
+#include <string>
+
+#include "env/file_system_tracer.h"
+#include "port/port.h"
+#include "rocksdb/env.h"
+#include "rocksdb/file_system.h"
+
+namespace ROCKSDB_NAMESPACE {
+
+// SequentialFileReader is a wrapper on top of Env::SequentialFile. It handles
+// Buffered (i.e when page cache is enabled) and Direct (with O_DIRECT / page
+// cache disabled) reads appropriately, and also updates the IO stats.
+class SequentialFileReader {
+ private:
+#ifndef ROCKSDB_LITE
+  void NotifyOnFileReadFinish(
+      uint64_t offset, size_t length,
+      const FileOperationInfo::StartTimePoint& start_ts,
+      const FileOperationInfo::FinishTimePoint& finish_ts,
+      const Status& status) const {
+    FileOperationInfo info(FileOperationType::kRead, file_name_, start_ts,
+                           finish_ts, status);
+    info.offset = offset;
+    info.length = length;
+
+    for (auto& listener : listeners_) {
+      listener->OnFileReadFinish(info);
+    }
+    info.status.PermitUncheckedError();
+  }
+
+  void AddFileIOListeners(
+      const std::vector<std::shared_ptr<EventListener>>& listeners) {
+    std::for_each(listeners.begin(), listeners.end(),
+                  [this](const std::shared_ptr<EventListener>& e) {
+                    if (e->ShouldBeNotifiedOnFileIO()) {
+                      listeners_.emplace_back(e);
+                    }
+                  });
+  }
+#endif  // ROCKSDB_LITE
+
+  bool ShouldNotifyListeners() const { return !listeners_.empty(); }
+
+  std::string file_name_;
+  FSSequentialFilePtr file_;
+  std::atomic<size_t> offset_{0};  // read offset
+  std::vector<std::shared_ptr<EventListener>> listeners_{};
+  RateLimiter* rate_limiter_;
+
+ public:
+  explicit SequentialFileReader(
+      std::unique_ptr<FSSequentialFile>&& _file, const std::string& _file_name,
+      const std::shared_ptr<IOTracer>& io_tracer = nullptr,
+      const std::vector<std::shared_ptr<EventListener>>& listeners = {},
+      RateLimiter* rate_limiter =
+          nullptr)  // TODO: migrate call sites to provide rate limiter
+      : file_name_(_file_name),
+        file_(std::move(_file), io_tracer, _file_name),
+        listeners_(),
+        rate_limiter_(rate_limiter) {
+#ifndef ROCKSDB_LITE
+    AddFileIOListeners(listeners);
+#else
+    (void)listeners;
+#endif
+  }
+
+  explicit SequentialFileReader(
+      std::unique_ptr<FSSequentialFile>&& _file, const std::string& _file_name,
+      size_t _readahead_size,
+      const std::shared_ptr<IOTracer>& io_tracer = nullptr,
+      const std::vector<std::shared_ptr<EventListener>>& listeners = {},
+      RateLimiter* rate_limiter =
+          nullptr)  // TODO: migrate call sites to provide rate limiter
+      : file_name_(_file_name),
+        file_(NewReadaheadSequentialFile(std::move(_file), _readahead_size),
+              io_tracer, _file_name),
+        listeners_(),
+        rate_limiter_(rate_limiter) {
+#ifndef ROCKSDB_LITE
+    AddFileIOListeners(listeners);
+#else
+    (void)listeners;
+#endif
+  }
+  static IOStatus Create(const std::shared_ptr<FileSystem>& fs,
+                         const std::string& fname, const FileOptions& file_opts,
+                         std::unique_ptr<SequentialFileReader>* reader,
+                         IODebugContext* dbg, RateLimiter* rate_limiter);
+
+  SequentialFileReader(const SequentialFileReader&) = delete;
+  SequentialFileReader& operator=(const SequentialFileReader&) = delete;
+
+  // `rate_limiter_priority` is used to charge the internal rate limiter when
+  // enabled. The special value `Env::IO_TOTAL` makes this operation bypass the
+  // rate limiter. The amount charged to the internal rate limiter is n, even
+  // when less than n bytes are actually read (e.g. at end of file). To avoid
+  // overcharging the rate limiter, the caller can use file size to cap n to
+  // read until end of file.
+  IOStatus Read(size_t n, Slice* result, char* scratch,
+                Env::IOPriority rate_limiter_priority);
+
+  IOStatus Skip(uint64_t n);
+
+  FSSequentialFile* file() { return file_.get(); }
+
+  std::string file_name() { return file_name_; }
+
+  bool use_direct_io() const { return file_->use_direct_io(); }
+
+ private:
+  // NewReadaheadSequentialFile provides a wrapper over SequentialFile to
+  // always prefetch additional data with every read.
+  static std::unique_ptr<FSSequentialFile> NewReadaheadSequentialFile(
+      std::unique_ptr<FSSequentialFile>&& file, size_t readahead_size);
+};
+}  // namespace ROCKSDB_NAMESPACE