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94 lines
2.2 KiB
C++
94 lines
2.2 KiB
C++
/*
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* \brief A guard for arbitrary allocators to limit memory exhaustion
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* \author Stefan Kalkowski
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* \date 2010-08-20
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*/
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/*
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* Copyright (C) 2010-2013 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 General Public License version 2.
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*/
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#ifndef _ALLOCATOR_GUARD_H_
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#define _ALLOCATOR_GUARD_H_
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#include <base/allocator.h>
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#include <base/printf.h>
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#include <base/stdint.h>
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namespace Genode {
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/**
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* This class acts as guard for arbitrary allocators to limit
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* memory exhaustion
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*/
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class Allocator_guard : public Allocator
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{
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private:
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Allocator *_allocator; /* allocator to guard */
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size_t _amount; /* total amount */
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size_t _consumed; /* already consumed bytes */
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public:
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Allocator_guard(Allocator *allocator, size_t amount)
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: _allocator(allocator), _amount(amount), _consumed(0) { }
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/**
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* Extend allocation limit
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*/
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void upgrade(size_t additional_amount) {
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_amount += additional_amount; }
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/*************************
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** Allocator interface **
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*************************/
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/**
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* Allocate block
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*
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* \param size block size to allocate
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* \param out_addr resulting pointer to the new block,
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* undefined in the error case
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* \return true on success
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*/
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bool alloc(size_t size, void **out_addr)
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{
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if ((_amount - _consumed) < (size + _allocator->overhead(size))) {
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PWRN("Quota exceeded! amount=%zd, size=%zd, consumed=%zd",
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_amount, (size + _allocator->overhead(size)), _consumed);
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return false;
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}
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bool b = _allocator->alloc(size, out_addr);
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if (b)
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_consumed += size + _allocator->overhead(size);
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return b;
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}
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/**
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* Free block a previously allocated block
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*/
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void free(void *addr, size_t size)
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{
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_allocator->free(addr, size);
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_consumed -= size - _allocator->overhead(size);
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}
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/**
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* Return total amount of backing store consumed by the allocator
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*/
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size_t consumed() { return _consumed; }
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/**
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* Return meta-data overhead per block
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*/
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size_t overhead(size_t size) { return _allocator->overhead(size); }
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};
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}
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#endif /* _ALLOCATOR_GUARD_H_ */
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