133 lines
2.9 KiB
C++
133 lines
2.9 KiB
C++
/*
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* \brief Utility for buffering XML nodes
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* \author Norman Feske
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* \date 2017-03-03
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*/
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/*
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* Copyright (C) 2017 Genode Labs GmbH
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*
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* This file is part of the Genode OS framework, which is distributed
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* under the terms of the GNU Affero General Public License version 3.
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*/
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#ifndef _OS__BUFFERED_XML_H_
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#define _OS__BUFFERED_XML_H_
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/* Genode includes */
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#include <util/retry.h>
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#include <util/xml_node.h>
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#include <util/xml_generator.h>
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#include <base/allocator.h>
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namespace Genode { class Buffered_xml; }
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class Genode::Buffered_xml
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{
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private:
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Allocator &_alloc;
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struct Allocation { char *ptr; size_t size; } const _allocation;
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Xml_node const _xml { _allocation.ptr, _allocation.size };
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/**
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* \throw Allocator::Out_of_memory
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*/
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Allocation _copy_xml_node(Xml_node node)
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{
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Allocation allocation { };
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node.with_raw_node([&] (char const *start, size_t length) {
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allocation = Allocation { (char *)_alloc.alloc(length), length };
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Genode::memcpy(allocation.ptr, start, length);
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});
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return allocation;
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}
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/**
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* Generate XML into allocated buffer
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*
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* \throw Allocation::Out_of_memory
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*/
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template <typename FN>
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Allocation _generate(char const *node_name, FN const &fn, size_t size)
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{
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Allocation allocation { };
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retry<Xml_generator::Buffer_exceeded>(
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[&] () {
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allocation = Allocation { (char *)_alloc.alloc(size), size };
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Xml_generator xml(allocation.ptr, size, node_name,
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[&] () { fn(xml); }); },
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[&] () {
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_alloc.free(allocation.ptr, allocation.size);
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allocation = { };
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size = size*2;
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}
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);
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return allocation;
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}
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/*
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* Noncopyable
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*/
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Buffered_xml(Buffered_xml const &);
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Buffered_xml &operator = (Buffered_xml const &);
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public:
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/**
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* Constructor for buffering a copy of the specified XML node
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*
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* \throw Allocator::Out_of_memory
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*/
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Buffered_xml(Allocator &alloc, Xml_node node)
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:
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_alloc(alloc), _allocation(_copy_xml_node(node))
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{ }
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struct Min_size { size_t value; };
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/**
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* Constructor for buffering generated XML
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*
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* \param name name of top-level XML node
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* \param fn functor that takes an 'Xml_generator &' as argument
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* \param size initial allocation size
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*
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* \throw Allocator::Out_of_memory
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*/
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template <typename FN>
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Buffered_xml(Allocator &alloc, char const *name, FN const &fn, Min_size size)
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:
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_alloc(alloc), _allocation(_generate(name, fn, size.value))
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{ }
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template <typename FN>
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Buffered_xml(Allocator &alloc, char const *name, FN const &fn)
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:
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Buffered_xml(alloc, name, fn, Min_size{4000})
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{ }
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~Buffered_xml() { _alloc.free(_allocation.ptr, _allocation.size); }
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/*
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* \deprecated Use 'with_xml_node' instead
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*/
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Xml_node xml() const { return _xml; }
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/**
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* Call functor 'fn' with 'Xml_node const &' as argument
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*/
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template <typename FN>
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void with_xml_node(FN const &fn) const { fn(_xml); }
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};
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#endif /* _OS__BUFFERED_XML_H_ */
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