Index: base/memory/discardable_shared_memory.cc |
diff --git a/base/memory/discardable_shared_memory.cc b/base/memory/discardable_shared_memory.cc |
index 1b50da260e09b566807fb40e72a1ab0638db11d3..d0eaca1a66219eafee72db30d3e91170e4055e98 100644 |
--- a/base/memory/discardable_shared_memory.cc |
+++ b/base/memory/discardable_shared_memory.cc |
@@ -4,9 +4,8 @@ |
#include "base/memory/discardable_shared_memory.h" |
-#if defined(OS_POSIX) && !defined(OS_NACL) |
-// For madvise() which is available on all POSIX compatible systems. |
-#include <sys/mman.h> |
+#if defined(OS_POSIX) |
+#include <unistd.h> |
#endif |
#include <algorithm> |
@@ -302,7 +301,11 @@ |
bool DiscardableSharedMemory::Purge(Time current_time) { |
// Calls to this function must be synchronized properly. |
DFAKE_SCOPED_LOCK(thread_collision_warner_); |
- DCHECK(shared_memory_.memory()); |
+ |
+ // Early out if not mapped. This can happen if the segment was previously |
+ // unmapped using a call to Close(). |
+ if (!shared_memory_.memory()) |
+ return true; |
SharedState old_state(SharedState::UNLOCKED, last_known_usage_); |
SharedState new_state(SharedState::UNLOCKED, Time()); |
@@ -323,25 +326,6 @@ |
return false; |
} |
-#if defined(OS_POSIX) && !defined(OS_NACL) |
-// Linux and Android provide MADV_REMOVE which is preferred as it has a |
-// behavior that can be verified in tests. Other POSIX flavors (MacOSX, BSDs), |
-// provide MADV_FREE which has the same result but memory is purged lazily. |
-#if defined(OS_LINUX) || defined(OS_ANDROID) |
-#define MADV_PURGE_ARGUMENT MADV_REMOVE |
-#else |
-#define MADV_PURGE_ARGUMENT MADV_FREE |
-#endif |
- // Advise the kernel to remove resources associated with purged pages. |
- // Subsequent accesses of memory pages will succeed, but might result in |
- // zero-fill-on-demand pages. |
- if (madvise(reinterpret_cast<char*>(shared_memory_.memory()) + |
- AlignToPageSize(sizeof(SharedState)), |
- AlignToPageSize(mapped_size_), MADV_PURGE_ARGUMENT)) { |
- DPLOG(ERROR) << "madvise() failed"; |
- } |
-#endif |
- |
last_known_usage_ = Time(); |
return true; |
} |
@@ -369,6 +353,26 @@ |
shared_memory_.Close(); |
} |
+#if defined(DISCARDABLE_SHARED_MEMORY_SHRINKING) |
+void DiscardableSharedMemory::Shrink() { |
+#if defined(OS_POSIX) |
+ SharedMemoryHandle handle = shared_memory_.handle(); |
+ if (!SharedMemory::IsHandleValid(handle)) |
+ return; |
+ |
+ // Truncate shared memory to size of SharedState. |
+ if (HANDLE_EINTR(ftruncate(SharedMemory::GetFdFromSharedMemoryHandle(handle), |
+ AlignToPageSize(sizeof(SharedState)))) != 0) { |
+ DPLOG(ERROR) << "ftruncate() failed"; |
+ return; |
+ } |
+ mapped_size_ = 0; |
+#else |
+ NOTIMPLEMENTED(); |
+#endif |
+} |
+#endif |
+ |
Time DiscardableSharedMemory::Now() const { |
return Time::Now(); |
} |