Remove unused locking functionality from base::SharedMemory.

The only existing consumers of the locking functionality were two unit tests for
SharedMemory.

The first unit test only tested the locking functionality across threads, so I
removed the test.

The second unit test was intended to test cross-process functionality of
base::SharedMemory, and used the locking functionality as a synchronization
method between processes. I rewrote the test to actually test Shared Memory
functionality, as the original test only tested synchronization between
processes, and would have succeeded even if Shared Memory didn't work. I
replaced the synchronization with compare and swap operations.

BUG=466437, 345734

Review URL: https://codereview.chromium.org/1167863002

Cr-Commit-Position: refs/heads/master@{#335135}

1 files changed, 0 insertions, 37 deletions

diff --git a/base/memory/shared_memory_posix.cc b/base/memory/shared_memory_posix.cc
index 35d746e..8aaa9ce 100644
--- a/base/memory/shared_memory_posix.cc
+++ b/base/memory/shared_memory_posix.cc
@@ -4,16 +4,13 @@
 
 #include "base/memory/shared_memory.h"
 
-#include <errno.h>
 #include <fcntl.h>
 #include <sys/mman.h>
 #include <sys/stat.h>
-#include <sys/types.h>
 #include <unistd.h>
 
 #include "base/files/file_util.h"
 #include "base/files/scoped_file.h"
-#include "base/lazy_instance.h"
 #include "base/logging.h"
 #include "base/posix/eintr_wrapper.h"
 #include "base/posix/safe_strerror.h"
@@ -21,9 +18,6 @@
 #include "base/profiler/scoped_tracker.h"
 #include "base/scoped_generic.h"
 #include "base/strings/utf_string_conversions.h"
-#include "base/synchronization/lock.h"
-#include "base/threading/platform_thread.h"
-#include "base/threading/thread_restrictions.h"
 
 #if defined(OS_MACOSX)
 #include "base/mac/foundation_util.h"
@@ -38,8 +32,6 @@ namespace base {
 
 namespace {
 
-LazyInstance<Lock>::Leaky g_thread_lock_ = LAZY_INSTANCE_INITIALIZER;
-
 struct ScopedPathUnlinkerTraits {
   static FilePath* InvalidValue() { return nullptr; }
 
@@ -414,16 +406,6 @@ void SharedMemory::Close() {
   }
 }
 
-void SharedMemory::LockDeprecated() {
-  g_thread_lock_.Get().Acquire();
-  LockOrUnlockCommon(F_LOCK);
-}
-
-void SharedMemory::UnlockDeprecated() {
-  LockOrUnlockCommon(F_ULOCK);
-  g_thread_lock_.Get().Release();
-}
-
 #if !defined(OS_ANDROID)
 bool SharedMemory::PrepareMapFile(ScopedFILE fp, ScopedFD readonly_fd) {
   DCHECK_EQ(-1, mapped_file_);
@@ -491,25 +473,6 @@ bool SharedMemory::FilePathForMemoryName(const std::string& mem_name,
 }
 #endif  // !defined(OS_ANDROID)
 
-void SharedMemory::LockOrUnlockCommon(int function) {
-  DCHECK_GE(mapped_file_, 0);
-  while (lockf(mapped_file_, function, 0) < 0) {
-    if (errno == EINTR) {
-      continue;
-    } else if (errno == ENOLCK) {
-      // temporary kernel resource exaustion
-      base::PlatformThread::Sleep(base::TimeDelta::FromMilliseconds(500));
-      continue;
-    } else {
-      NOTREACHED() << "lockf() failed."
-                   << " function:" << function
-                   << " fd:" << mapped_file_
-                   << " errno:" << errno
-                   << " msg:" << base::safe_strerror(errno);
-    }
-  }
-}
-
 bool SharedMemory::ShareToProcessCommon(ProcessHandle process,
                                         SharedMemoryHandle* new_handle,
                                         bool close_self,