f3eade2f62
Drop the AGPL license in favor of a source-available license. See the blog post [1] for details. [1] https://www.scylladb.com/2024/12/18/why-were-moving-to-a-source-available-license/
35 lines
1.2 KiB
C++
35 lines
1.2 KiB
C++
/*
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* Copyright (C) 2022-present ScyllaDB
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*/
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/*
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* SPDX-License-Identifier: LicenseRef-ScyllaDB-Source-Available-1.0
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*/
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#pragma once
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#include <seastar/core/sharded.hh>
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#include "readers/mutation_reader_fwd.hh"
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#include "schema/schema_fwd.hh"
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class reader_permit;
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/// Make a foreign_reader.
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///
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/// foreign_reader is a local representant of a reader located on a remote
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/// shard. Manages its lifecycle and takes care of seamlessly transferring
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/// produced fragments. Fragments are *copied* between the shards, a
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/// bufferful at a time.
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/// To maximize throughput read-ahead is used. After each fill_buffer() or
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/// fast_forward_to() a read-ahead (a fill_buffer() on the remote reader) is
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/// issued. This read-ahead runs in the background and is brought back to
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/// foreground on the next fill_buffer() or fast_forward_to() call.
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/// If the reader resides on this shard (the shard where make_foreign_reader()
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/// is called) there is no need to wrap it in foreign_reader, just return it as
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/// is.
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mutation_reader make_foreign_reader(schema_ptr schema,
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reader_permit permit,
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foreign_ptr<std::unique_ptr<mutation_reader>> reader,
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streamed_mutation::forwarding fwd_sm = streamed_mutation::forwarding::no);
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