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7a04d1f662
The file_input_stream interface was messy: it was not fiber safe (e.g., code
doing seek() in the middle of an ongoing read_exactly()), and went against
the PIMPL philosophy.
So this patch removes the file_input_stream class, and replaces it with a
completely different design:
We now have in fstream.hh a global function:
input_stream<char>
make_file_input_stream(
lw_shared_ptr<file> file, uint64_t offset = 0,
uint64_t buffer_size = 8192);
In other words, instead of "seeking" in an input stream, we just open a new
input stream object at a particular offset of the given file. Multiple input
streams might be concurrently active on the same file.
Note how make_file_input_stream now returns a regular "input_stream", not a
subtype, and it can be used just like any normal input_stream to read the stream
starting at the given position.
This patch makes "input_stream" a "final" type: we no longer subclass it in our
code, and we shouldn't in the future because it goes against the PIMPL design
(the subclass should be of the inner workings, like the data_source_impl, not
of input_stream).
Signed-off-by: Nadav Har'El <nyh@cloudius-systems.com>
41 lines
1.5 KiB
C++
41 lines
1.5 KiB
C++
/*
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* This file is open source software, licensed to you under the terms
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* of the Apache License, Version 2.0 (the "License"). See the NOTICE file
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* distributed with this work for additional information regarding copyright
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* ownership. You may not use this file except in compliance with the License.
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*
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing,
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* software distributed under the License is distributed on an
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* "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
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* KIND, either express or implied. See the License for the
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* specific language governing permissions and limitations
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* under the License.
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*/
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/*
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* Copyright (C) 2015 Cloudius Systems, Ltd.
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*/
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#pragma once
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// File <-> streams adapters
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//
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// Seastar files are block-based due to the reliance on DMA - you must read
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// on sector boundaries. The adapters in this file provide a byte stream
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// interface to files, while retaining the zero-copy characteristics of
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// seastar files.
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#include "file.hh"
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#include "iostream.hh"
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#include "shared_ptr.hh"
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// Create an input_stream for reading starting at a given position of the
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// given file. Multiple fibers of execution (continuations) may safely open
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// multiple input streams concurrently for the same file.
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input_stream<char> make_file_input_stream(
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lw_shared_ptr<file> file, uint64_t offset = 0,
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uint64_t buffer_size = 8192);
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