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/*
* Copyright 2012, The Android Open Source Project
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* * Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* * Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS ``AS IS'' AND ANY
* EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
* PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR
* CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
* EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
* PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
* PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY
* OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
* OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
#define LOG_TAG "LinearAllocator"
#define LOG_NDEBUG 1
#include "config.h"
#include "LinearAllocator.h"
#include "AndroidLog.h"
namespace WebCore {
// The ideal size of a page allocation
#define TARGET_PAGE_SIZE 16384 // 16kb
// our pool needs to big enough to hold at least this many items
#define MIN_OBJECT_COUNT 4
// The maximum amount of wasted space we can have per page
// Allocations exceeding this will have their own dedicated page
// If this is too low, we will malloc too much
// Too high, and we may waste too much space
#define MAX_WASTE_SIZE ((size_t)256)
#define ALIGN(x) (x + (x % sizeof(int)))
#if LOG_NDEBUG
#define ADD_ALLOCATION(size)
#define RM_ALLOCATION(size)
#else
#include <utils/Thread.h>
static size_t s_totalAllocations = 0;
static double s_lastLogged = 0;
static android::Mutex s_mutex;
static void _logUsageLocked() {
double now = currentTimeMS();
if (now - s_lastLogged > 5) {
s_lastLogged = now;
ALOGV("Total memory usage: %d kb", s_totalAllocations / 1024);
}
}
static void _addAllocation(size_t size) {
android::AutoMutex lock(s_mutex);
s_totalAllocations += size;
_logUsageLocked();
}
#define ADD_ALLOCATION(size) _addAllocation(size);
#define RM_ALLOCATION(size) _addAllocation(-size);
#endif
class LinearAllocator::Page {
public:
Page* next() { return m_nextPage; }
void setNext(Page* next) { m_nextPage = next; }
Page()
: m_nextPage(0)
{}
void* start()
{
return (void*) (((unsigned)this) + sizeof(LinearAllocator::Page));
}
void* end(int pageSize)
{
return (void*) (((unsigned)start()) + pageSize);
}
private:
Page(const Page& other) {}
Page* m_nextPage;
};
LinearAllocator::LinearAllocator(size_t averageAllocSize)
: m_next(0)
, m_currentPage(0)
, m_pages(0)
{
if (averageAllocSize) {
int usable_page_size = TARGET_PAGE_SIZE - sizeof(LinearAllocator::Page);
int pcount = usable_page_size / averageAllocSize;
if (pcount < MIN_OBJECT_COUNT)
pcount = MIN_OBJECT_COUNT;
m_pageSize = pcount * averageAllocSize + sizeof(LinearAllocator::Page);
} else
m_pageSize = TARGET_PAGE_SIZE;
m_pageSize = ALIGN(m_pageSize);
m_maxAllocSize = std::min(MAX_WASTE_SIZE, (m_pageSize - sizeof(LinearAllocator::Page)));
}
LinearAllocator::~LinearAllocator(void)
{
Page* p = m_pages;
while (p) {
Page* next = p->next();
delete p;
RM_ALLOCATION(m_pageSize);
p = next;
}
}
void* LinearAllocator::start(Page* p)
{
return ((char*)p) + sizeof(Page);
}
void* LinearAllocator::end(Page* p)
{
return ((char*)p) + m_pageSize;
}
void LinearAllocator::ensureNext(size_t size)
{
if (m_next && ((char*)m_next + size) <= end(m_currentPage))
return;
Page* p = newPage();
if (m_currentPage)
m_currentPage->setNext(p);
m_currentPage = p;
if (!m_pages)
m_pages = m_currentPage;
m_next = start(m_currentPage);
}
unsigned LinearAllocator::memusage()
{
unsigned memusage = 0;
Page* p = m_pages;
while (p) {
memusage += m_pageSize;
p = p->next();
}
return memusage;
}
void* LinearAllocator::alloc(size_t size)
{
size = ALIGN(size);
if (size > m_maxAllocSize) {
// Allocation is too large, create a dedicated page for the allocation
ADD_ALLOCATION(size);
void* buf = malloc(size + sizeof(LinearAllocator::Page));
Page* page = new (buf) Page();
page->setNext(m_pages);
m_pages = page;
if (!m_currentPage)
m_currentPage = m_pages;
return start(page);
}
ensureNext(size);
void* ptr = m_next;
m_next = ((char*)m_next) + size;
return ptr;
}
void LinearAllocator::rewindTo(void* ptr)
{
// Don't bother rewinding across pages
if (ptr >= start(m_currentPage) && ptr < end(m_currentPage))
m_next = ptr;
}
LinearAllocator::Page* LinearAllocator::newPage()
{
ADD_ALLOCATION(m_pageSize);
void* buf = malloc(m_pageSize);
return new (buf) Page();
}
} // namespace WebCore
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