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>
67 lines
2.1 KiB
C++
67 lines
2.1 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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// Demonstration of file_input_stream. Don't expect stellar performance
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// since no read-ahead or caching is done yet.
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#include "core/fstream.hh"
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#include "core/app-template.hh"
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#include "core/shared_ptr.hh"
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#include "core/reactor.hh"
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#include <algorithm>
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struct reader {
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reader(file f) : is(make_file_input_stream(
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make_lw_shared<file>(std::move(f)), 0, 4096)) {}
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input_stream<char> is;
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size_t count = 0;
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// for input_stream::consume():
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template <typename Done>
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void operator()(temporary_buffer<char> data, Done&& done) {
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if (data.empty()) {
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done(std::move(data));
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} else {
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count += std::count(data.begin(), data.end(), '\n');
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// FIXME: last line without \n?
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}
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}
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};
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int main(int ac, char** av) {
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app_template app;
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namespace bpo = boost::program_options;
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app.add_positional_options({
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{ "file", bpo::value<std::string>(), "File to process", 1 },
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});
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app.run(ac, av, [&app] {
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auto fname = app.configuration()["file"].as<std::string>();
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engine().open_file_dma(fname, open_flags::ro | open_flags::create).then([] (file f) {
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auto r = make_shared<reader>(std::move(f));
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r->is.consume(*r).then([r] {
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print("%d lines\n", r->count);
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engine().exit(0);
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});
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});
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});
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}
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