1 files changed, 38 insertions, 0 deletions
diff --git a/src/rocksdb/db/blob/prefetch_buffer_collection.h b/src/rocksdb/db/blob/prefetch_buffer_collection.h
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index 000000000..b973eddc0
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+++ b/src/rocksdb/db/blob/prefetch_buffer_collection.h
@@ -0,0 +1,38 @@
+//  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).
+
+#pragma once
+
+#include <cassert>
+#include <cstdint>
+#include <memory>
+#include <unordered_map>
+
+#include "file/file_prefetch_buffer.h"
+#include "rocksdb/rocksdb_namespace.h"
+
+namespace ROCKSDB_NAMESPACE {
+
+// A class that owns a collection of FilePrefetchBuffers using the file number
+// as key. Used for implementing compaction readahead for blob files. Designed
+// to be accessed by a single thread only: every (sub)compaction needs its own
+// buffers since they are guaranteed to read different blobs from different
+// positions even when reading the same file.
+class PrefetchBufferCollection {
+ public:
+  explicit PrefetchBufferCollection(uint64_t readahead_size)
+      : readahead_size_(readahead_size) {
+    assert(readahead_size_ > 0);
+  }
+
+  FilePrefetchBuffer* GetOrCreatePrefetchBuffer(uint64_t file_number);
+
+ private:
+  uint64_t readahead_size_;
+  std::unordered_map<uint64_t, std::unique_ptr<FilePrefetchBuffer>>
+      prefetch_buffers_;  // maps file number to prefetch buffer
+};
+
+}  // namespace ROCKSDB_NAMESPACE