michael@0: /*
michael@0:  * Copyright 2013 Google Inc.
michael@0:  *
michael@0:  * Use of this source code is governed by a BSD-style license that can be
michael@0:  * found in the LICENSE file.
michael@0:  */
michael@0: 
michael@0: #include "SkPurgeableMemoryBlock.h"
michael@0: 
michael@0: #include "android/ashmem.h"
michael@0: #include <sys/mman.h>
michael@0: #include <unistd.h>
michael@0: 
michael@0: bool SkPurgeableMemoryBlock::IsSupported() {
michael@0:     return true;
michael@0: }
michael@0: 
michael@0: #ifdef SK_DEBUG
michael@0: bool SkPurgeableMemoryBlock::PlatformSupportsPurgingAllUnpinnedBlocks() {
michael@0:     return false;
michael@0: }
michael@0: 
michael@0: bool SkPurgeableMemoryBlock::PurgeAllUnpinnedBlocks() {
michael@0:     return false;
michael@0: }
michael@0: 
michael@0: bool SkPurgeableMemoryBlock::purge() {
michael@0:     SkASSERT(!fPinned);
michael@0:     if (-1 != fFD) {
michael@0:         ashmem_purge_all_caches(fFD);
michael@0:         return true;
michael@0:     } else {
michael@0:         return false;
michael@0:     }
michael@0: }
michael@0: #endif
michael@0: 
michael@0: // ashmem likes lengths on page boundaries.
michael@0: static size_t round_to_page_size(size_t size) {
michael@0:     const size_t mask = getpagesize() - 1;
michael@0:     size_t newSize = (size + mask) & ~mask;
michael@0:     return newSize;
michael@0: }
michael@0: 
michael@0: SkPurgeableMemoryBlock::SkPurgeableMemoryBlock(size_t size)
michael@0:     : fAddr(NULL)
michael@0:     , fSize(round_to_page_size(size))
michael@0:     , fPinned(false)
michael@0:     , fFD(-1) {
michael@0: }
michael@0: 
michael@0: SkPurgeableMemoryBlock::~SkPurgeableMemoryBlock() {
michael@0:     if (-1 != fFD) {
michael@0:         munmap(fAddr, fSize);
michael@0:         close(fFD);
michael@0:     }
michael@0: }
michael@0: 
michael@0: void* SkPurgeableMemoryBlock::pin(SkPurgeableMemoryBlock::PinResult* pinResult) {
michael@0:     SkASSERT(!fPinned);
michael@0:     if (-1 == fFD) {
michael@0:         int fd = ashmem_create_region(NULL, fSize);
michael@0:         if (-1 == fd) {
michael@0:             SkDebugf("ashmem_create_region failed\n");
michael@0:             return NULL;
michael@0:         }
michael@0: 
michael@0:         int err = ashmem_set_prot_region(fd, PROT_READ | PROT_WRITE);
michael@0:         if (err != 0) {
michael@0:             SkDebugf("ashmem_set_prot_region failed\n");
michael@0:             close(fd);
michael@0:             return NULL;
michael@0:         }
michael@0: 
michael@0:         void* addr = mmap(NULL, fSize, PROT_READ | PROT_WRITE, MAP_PRIVATE, fd, 0);
michael@0:         if (-1 == (long) addr) {
michael@0:             SkDebugf("mmap failed\n");
michael@0:             close(fd);
michael@0:             return NULL;
michael@0:         }
michael@0:         fAddr = addr;
michael@0:         fFD = fd;
michael@0:         (void) ashmem_pin_region(fd, 0, 0);
michael@0:         *pinResult = kUninitialized_PinResult;
michael@0:         fPinned = true;
michael@0:     } else {
michael@0:         int pin = ashmem_pin_region(fFD, 0, 0);
michael@0:         if (ASHMEM_NOT_PURGED == pin) {
michael@0:             fPinned = true;
michael@0:             *pinResult = kRetained_PinResult;
michael@0:         } else if (ASHMEM_WAS_PURGED == pin) {
michael@0:             fPinned = true;
michael@0:             *pinResult = kUninitialized_PinResult;
michael@0:         } else {
michael@0:             // Failed.
michael@0:             munmap(fAddr, fSize);
michael@0:             close(fFD);
michael@0:             fFD = -1;
michael@0:             fAddr = NULL;
michael@0:         }
michael@0:     }
michael@0:     return fAddr;
michael@0: }
michael@0: 
michael@0: void SkPurgeableMemoryBlock::unpin() {
michael@0:     if (-1 != fFD) {
michael@0:         ashmem_unpin_region(fFD, 0, 0);
michael@0:         fPinned = false;
michael@0:     }
michael@0: }