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/*
* Copyright 2013 Google Inc.
*
* Use of this source code is governed by a BSD-style license that can be
* found in the LICENSE file.
*/
#include <unistd.h>
#include <sys/mman.h>
#include "SkDiscardableMemory.h"
#include "SkTypes.h"
#include "android/ashmem.h"
////////////////////////////////////////////////////////////////////////////////
namespace {
/**
* DiscardableMemory implementation that uses the Android kernel's
* ashmem (Android shared memory).
*/
class SkAshmemDiscardableMemory : public SkDiscardableMemory {
public:
SkAshmemDiscardableMemory(int fd, void* address, size_t size);
virtual ~SkAshmemDiscardableMemory();
virtual bool lock() SK_OVERRIDE;
virtual void* data() SK_OVERRIDE;
virtual void unlock() SK_OVERRIDE;
private:
bool fLocked;
int fFd;
void* fMemory;
const size_t fSize;
};
SkAshmemDiscardableMemory::SkAshmemDiscardableMemory(int fd,
void* address,
size_t size)
: fLocked(true) // Ashmem pages are pinned by default.
, fFd(fd)
, fMemory(address)
, fSize(size) {
SkASSERT(fFd >= 0);
SkASSERT(fMemory != NULL);
SkASSERT(fSize > 0);
}
SkAshmemDiscardableMemory::~SkAshmemDiscardableMemory() {
SkASSERT(!fLocked);
if (NULL != fMemory) {
munmap(fMemory, fSize);
}
if (fFd != -1) {
close(fFd);
}
}
bool SkAshmemDiscardableMemory::lock() {
SkASSERT(!fLocked);
if (-1 == fFd) {
fLocked = false;
return false;
}
SkASSERT(fMemory != NULL);
if (fLocked || (ASHMEM_NOT_PURGED == ashmem_pin_region(fFd, 0, 0))) {
fLocked = true;
return true;
} else {
munmap(fMemory, fSize);
fMemory = NULL;
close(fFd);
fFd = -1;
fLocked = false;
return false;
}
}
void* SkAshmemDiscardableMemory::data() {
SkASSERT(fLocked);
return fLocked ? fMemory : NULL;
}
void SkAshmemDiscardableMemory::unlock() {
SkASSERT(fLocked);
if (fLocked && (fFd != -1)) {
ashmem_unpin_region(fFd, 0, 0);
}
fLocked = false;
}
} // namespace
////////////////////////////////////////////////////////////////////////////////
SkDiscardableMemory* SkDiscardableMemory::Create(size_t bytes) {
// ashmem likes lengths on page boundaries.
const size_t mask = getpagesize() - 1;
size_t size = (bytes + mask) & ~mask;
static const char name[] = "Skia_Ashmem_Discardable_Memory";
int fd = ashmem_create_region(name, size);
if (fd < 0) {
return NULL;
}
if (0 != ashmem_set_prot_region(fd, PROT_READ | PROT_WRITE)) {
close(fd);
return NULL;
}
void* addr = mmap(NULL, size, PROT_READ | PROT_WRITE, MAP_PRIVATE, fd, 0);
if ((MAP_FAILED == addr) || (NULL == addr)) {
close(fd);
return NULL;
}
return SkNEW_ARGS(SkAshmemDiscardableMemory, (fd, addr, size));
}
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