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edc46d15f8
This commit simplifies the current implementation by overloading the length field with a padding indicator in addition to the zero-length head entry. This simplifies the iteration semantics as it eliminates the need for determining whether a zero-length entries is the actual head of the buffer or a padding at the buffer end. genodelabs/genode#4434
87 lines
2.3 KiB
C++
87 lines
2.3 KiB
C++
/*
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* \brief Wrapper for Trace::Buffer that adds some convenient functionality
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* \author Martin Stein
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* \date 2018-01-12
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*/
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/*
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* Copyright (C) 2018 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 _TRACE__TRACE_BUFFER_H_
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#define _TRACE__TRACE_BUFFER_H_
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/* Genode includes */
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#include <base/trace/buffer.h>
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/**
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* Wrapper for Trace::Buffer that adds some convenient functionality
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*/
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class Trace_buffer
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{
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private:
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Genode::Trace::Buffer &_buffer;
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Genode::Trace::Buffer::Entry _curr { _buffer.first() };
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unsigned _wrapped_count { 0 };
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public:
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Trace_buffer(Genode::Trace::Buffer &buffer) : _buffer(buffer) { }
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/**
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* Call functor for each entry that wasn't yet processed
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*/
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template <typename FUNC>
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void for_each_new_entry(FUNC && functor, bool update = true)
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{
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using namespace Genode;
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bool wrapped = _buffer.wrapped() != _wrapped_count;
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if (wrapped) {
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if ((_buffer.wrapped() - 1) != _wrapped_count) {
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warning("buffer wrapped multiple times; you might want to raise buffer size; curr_count=",
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_buffer.wrapped(), " last_count=", _wrapped_count);
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_curr = _buffer.first();
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}
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_wrapped_count = (unsigned)_buffer.wrapped();
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}
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Trace::Buffer::Entry entry { _curr };
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/**
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* Iterate over all entries that were not processed yet.
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*
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* A note on terminology: The head of the buffer marks the write
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* position. The first entry is the one that starts at the lowest
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* memory address. The next entry returns an invalid entry called
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* if the 'last' end of the buffer (highest address) was reached.
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*/
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for (; !entry.head(); entry = _buffer.next(entry)) {
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/* continue at first entry if we hit the end of the buffer */
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if (entry.last())
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entry = _buffer.first();
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/* skip empty entries */
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if (entry.empty())
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continue;
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/* functor may return false to continue processing later on */
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if (!functor(entry))
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break;
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}
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/* remember the next to be processed entry in _curr */
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if (update) _curr = entry;
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}
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void * address() const { return &_buffer; }
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};
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#endif /* _TRACE__TRACE_BUFFER_H_ */
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