Implement SkAshmemDiscardableMemory
- Implement ashmem-backed SkDiscardableMemory subclass:
This class in only accesible via the SkDiscardableMemory::Create()
function, which replaces the mock implementation in
SkDiscardableMemory_none.cpp
- Added SkDiscardableMemory_ashmem.cpp to the Android port of Skia
Removed SkDiscardableMemory_none.cpp from the Android port.
- Added DiscardableMemoryTest.
Still needs work.
- SkDiscardablePixelRef Bugfix:
onLockPixels() now calls SkDELETE on the SkDiscardableMemory pointer
when it fails to unlock.
- Improved documentation inside ashmem.h
BUG=
R=scroggo@google.com
Review URL: https://codereview.chromium.org/83563002
git-svn-id: http://skia.googlecode.com/svn/trunk/src@12608 2bbb7eff-a529-9590-31e7-b0007b416f81
diff --git a/ports/SkDiscardableMemory_ashmem.cpp b/ports/SkDiscardableMemory_ashmem.cpp
new file mode 100644
index 0000000..6f8684e
--- /dev/null
+++ b/ports/SkDiscardableMemory_ashmem.cpp
@@ -0,0 +1,114 @@
+/*
+ * 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));
+}
+
diff --git a/utils/android/ashmem.h b/utils/android/ashmem.h
index 278192b..94ffe1a 100644
--- a/utils/android/ashmem.h
+++ b/utils/android/ashmem.h
@@ -16,6 +16,12 @@
int ashmem_create_region(const char *name, size_t size);
int ashmem_set_prot_region(int fd, int prot);
+
+/**
+ * @return ASHMEM_NOT_PURGED if the memory was not purged.
+ * ASHMEM_WAS_PURGED if the memory was purged.
+ * -1 on error.
+ */
int ashmem_pin_region(int fd, size_t offset, size_t len);
int ashmem_unpin_region(int fd, size_t offset, size_t len);
int ashmem_get_size_region(int fd);
