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authorGravatar Abseil Team <absl-team@google.com>2017-09-24 08:20:48 -0700
committerGravatar Derek Mauro <dmauro@google.com>2017-09-25 10:12:29 -0400
commitcf6ab6bb2b800fae859ccc735f398d22a7336a00 (patch)
treeee16a94d16734d11f9e91518038e2712ca025433 /absl/base/internal
parent53c239d1fc161975dad32c654e1f42c0ec42f547 (diff)
Changes imported from Abseil "staging" branch:
- b527a3e4b36b644ac424e3c525b1cd393f6f6c40 Fix some typos in the usage examples by Jorg Brown <jorg@google.com> - 82be4a9adf3bb0ddafc0d46274969c99afffe870 Fix typo in optional.h comment. by Abseil Team <absl-team@google.com> - d6ee63bf8fc51fba074c23b33cebc28c808d7f07 Remove internal-only identifiers from code. by Daniel Katz <katzdm@google.com> - f9c3ad2f0d73f53b21603638af8b4bed636e79f4 Use easier understandable names for absl::StartsWith and ... by Abseil Team <absl-team@google.com> - 7c16c14fefee89c927b8789d6043c4691bcffc9b Add -Wno-missing-prototypes back to the LLVM copts. by Derek Mauro <dmauro@google.com> - 2f4b7d2e50c7023240242f1e15db60ccd7e8768d IWYU | absl/strings by Juemin Yang <jueminyang@google.com> - a99cbcc1daa34a2d6a2bb26de275e05173cc77e9 IWYU | absl/type by Juemin Yang <jueminyang@google.com> - 12e1146d0fc76c071d7e0ebaabb62f0a984fae66 Use LLVM_FLAGS and LLVM_TEST_FLAGS when --compiler=llvm. by Derek Mauro <dmauro@google.com> - cd6bea616abda558d0bace5bd77455662a233688 IWYU | absl/debugging by Juemin Yang <jueminyang@google.com> - d9a7382e59d46a8581b6b7a31cd5a48bb89326e9 IWYU | absl/synchronization by Juemin Yang <jueminyang@google.com> - 07ec7d6d5a4a666f4183c5d0ed9c342baa7b24bc IWYU | absl/numeric by Juemin Yang <jueminyang@google.com> - 12bfe40051f4270f8707e191af5652f83f2f750c Remove the RoundTrip{Float,Double}ToBuffer routines from ... by Jorg Brown <jorg@google.com> - eeb4fd67c9d97f66cb9475c3c5e51ab132f1c810 Adds conversion functions for converting between absl/tim... by Greg Miller <jgm@google.com> - 59a2108d05d4ea85dc5cc11e49b2cd2335d4295a Change Substitute to use %.6g formatting rather than 15/1... by Jorg Brown <jorg@google.com> - 394becb48e0fcd161642cdaac5120d32567e0ef8 IWYU | absl/meta by Juemin Yang <jueminyang@google.com> - 1e5da6e8da336699b2469dcf6dda025b9b0ec4c9 Rewrite atomic_hook.h to not use std::atomic<T*> under Wi... by Greg Falcon <gfalcon@google.com> GitOrigin-RevId: b527a3e4b36b644ac424e3c525b1cd393f6f6c40 Change-Id: I14e331d91c956ef045ac7927091a9f179716de0c
Diffstat (limited to 'absl/base/internal')
-rw-r--r--absl/base/internal/atomic_hook.h104
-rw-r--r--absl/base/internal/low_level_scheduling.h4
-rw-r--r--absl/base/internal/malloc_hook.cc26
-rw-r--r--absl/base/internal/raw_logging.cc8
-rw-r--r--absl/base/internal/scheduling_mode.h4
-rw-r--r--absl/base/internal/spinlock_wait.h4
-rw-r--r--absl/base/internal/sysinfo.cc5
-rw-r--r--absl/base/internal/sysinfo.h3
-rw-r--r--absl/base/internal/sysinfo_test.cc5
-rw-r--r--absl/base/internal/thread_identity.cc11
10 files changed, 91 insertions, 83 deletions
diff --git a/absl/base/internal/atomic_hook.h b/absl/base/internal/atomic_hook.h
index 1f9a8102..47d40139 100644
--- a/absl/base/internal/atomic_hook.h
+++ b/absl/base/internal/atomic_hook.h
@@ -18,28 +18,12 @@
#include <atomic>
#include <cassert>
+#include <cstdint>
#include <utility>
namespace absl {
namespace base_internal {
-// In current versions of MSVC (as of July 2017), a std::atomic<T> where T is a
-// pointer to function cannot be constant-initialized with an address constant
-// expression. That is, the following code does not compile:
-// void NoOp() {}
-// constexpr std::atomic<void(*)()> ptr(NoOp);
-//
-// This is the only compiler we support that seems to have this issue. We
-// conditionalize on MSVC here to use a fallback implementation. But we
-// should revisit this occasionally. If MSVC fixes this compiler bug, we
-// can then change this to be conditionalized on the value on _MSC_FULL_VER
-// instead.
-#ifdef _MSC_FULL_VER
-#define ABSL_HAVE_FUNCTION_ADDRESS_CONSTANT_EXPRESSION 0
-#else
-#define ABSL_HAVE_FUNCTION_ADDRESS_CONSTANT_EXPRESSION 1
-#endif
-
template <typename T>
class AtomicHook;
@@ -55,7 +39,7 @@ class AtomicHook<ReturnType (*)(Args...)> {
public:
using FnPtr = ReturnType (*)(Args...);
- constexpr AtomicHook() : hook_(DummyFunction) {}
+ constexpr AtomicHook() : hook_(kInitialValue) {}
// Stores the provided function pointer as the value for this hook.
//
@@ -64,28 +48,16 @@ class AtomicHook<ReturnType (*)(Args...)> {
// as a memory_order_release operation, and read accesses are implemented as
// memory_order_acquire.
void Store(FnPtr fn) {
- assert(fn);
- FnPtr expected = DummyFunction;
- hook_.compare_exchange_strong(expected, fn, std::memory_order_acq_rel,
- std::memory_order_acquire);
- // If the compare and exchange failed, make sure that's because hook_ was
- // already set to `fn` by an earlier call. Any other state reflects an API
- // violation (calling Store() multiple times with different values).
- //
- // Avoid ABSL_RAW_CHECK, since raw logging depends on AtomicHook.
- assert(expected == DummyFunction || expected == fn);
+ bool success = DoStore(fn);
+ static_cast<void>(success);
+ assert(success);
}
// Invokes the registered callback. If no callback has yet been registered, a
// default-constructed object of the appropriate type is returned instead.
template <typename... CallArgs>
ReturnType operator()(CallArgs&&... args) const {
- FnPtr hook = hook_.load(std::memory_order_acquire);
- if (ABSL_HAVE_FUNCTION_ADDRESS_CONSTANT_EXPRESSION || hook) {
- return hook(std::forward<CallArgs>(args)...);
- } else {
- return ReturnType();
- }
+ return DoLoad()(std::forward<CallArgs>(args)...);
}
// Returns the registered callback, or nullptr if none has been registered.
@@ -98,23 +70,79 @@ class AtomicHook<ReturnType (*)(Args...)> {
// Load()() unless you must conditionalize behavior on whether a hook was
// registered.
FnPtr Load() const {
- FnPtr ptr = hook_.load(std::memory_order_acquire);
+ FnPtr ptr = DoLoad();
return (ptr == DummyFunction) ? nullptr : ptr;
}
private:
-#if ABSL_HAVE_FUNCTION_ADDRESS_CONSTANT_EXPRESSION
static ReturnType DummyFunction(Args...) {
return ReturnType();
}
+
+ // Current versions of MSVC (as of September 2017) have a broken
+ // implementation of std::atomic<T*>: Its constructor attempts to do the
+ // equivalent of a reinterpret_cast in a constexpr context, which is not
+ // allowed.
+ //
+ // This causes an issue when building with LLVM under Windows. To avoid this,
+ // we use a less-efficient, intptr_t-based implementation on Windows.
+
+#ifdef _MSC_FULL_VER
+#define ABSL_HAVE_WORKING_ATOMIC_POINTER 0
#else
- static constexpr FnPtr DummyFunction = nullptr;
+#define ABSL_HAVE_WORKING_ATOMIC_POINTER 1
#endif
+#if ABSL_HAVE_WORKING_ATOMIC_POINTER
+ static constexpr FnPtr kInitialValue = &DummyFunction;
+
+ // Return the stored value, or DummyFunction if no value has been stored.
+ FnPtr DoLoad() const { return hook_.load(std::memory_order_acquire); }
+
+ // Store the given value. Returns false if a different value was already
+ // stored to this object.
+ bool DoStore(FnPtr fn) {
+ assert(fn);
+ FnPtr expected = DummyFunction;
+ hook_.compare_exchange_strong(expected, fn, std::memory_order_acq_rel,
+ std::memory_order_acquire);
+ const bool store_succeeded = (expected == DummyFunction);
+ const bool same_value_already_stored = (expected == fn);
+ return store_succeeded || same_value_already_stored;
+ }
+
std::atomic<FnPtr> hook_;
+#else // !ABSL_HAVE_WORKING_ATOMIC_POINTER
+ // Use a sentinel value unlikely to be the address of an actual function.
+ static constexpr intptr_t kInitialValue = 0;
+
+ static_assert(sizeof(intptr_t) >= sizeof(FnPtr),
+ "intptr_t can't contain a function pointer");
+
+ FnPtr DoLoad() const {
+ const intptr_t value = hook_.load(std::memory_order_acquire);
+ if (value == 0) {
+ return DummyFunction;
+ }
+ return reinterpret_cast<FnPtr>(value);
+ }
+
+ bool DoStore(FnPtr fn) {
+ assert(fn);
+ const auto value = reinterpret_cast<intptr_t>(fn);
+ intptr_t expected = 0;
+ hook_.compare_exchange_strong(expected, value, std::memory_order_acq_rel,
+ std::memory_order_acquire);
+ const bool store_succeeded = (expected == 0);
+ const bool same_value_already_stored = (expected == value);
+ return store_succeeded || same_value_already_stored;
+ }
+
+ std::atomic<intptr_t> hook_;
+#endif
};
-#undef ABSL_HAVE_FUNCTION_ADDRESS_CONSTANT_EXPRESSION
+#undef ABSL_HAVE_WORKING_ATOMIC_POINTER
} // namespace base_internal
} // namespace absl
diff --git a/absl/base/internal/low_level_scheduling.h b/absl/base/internal/low_level_scheduling.h
index a01d1c03..e716f2b4 100644
--- a/absl/base/internal/low_level_scheduling.h
+++ b/absl/base/internal/low_level_scheduling.h
@@ -12,8 +12,8 @@
// See the License for the specific language governing permissions and
// limitations under the License.
//
-// Core interfaces and definitions used by by low-level //base interfaces such
-// as SpinLock.
+// Core interfaces and definitions used by by low-level interfaces such as
+// SpinLock.
#ifndef ABSL_BASE_INTERNAL_LOW_LEVEL_SCHEDULING_H_
#define ABSL_BASE_INTERNAL_LOW_LEVEL_SCHEDULING_H_
diff --git a/absl/base/internal/malloc_hook.cc b/absl/base/internal/malloc_hook.cc
index 4f5a0bef..7165d4cb 100644
--- a/absl/base/internal/malloc_hook.cc
+++ b/absl/base/internal/malloc_hook.cc
@@ -453,16 +453,13 @@ void MallocHook::InvokeSbrkHookSlow(const void* result, ptrdiff_t increment) {
} // namespace base_internal
} // namespace absl
-ABSL_DEFINE_ATTRIBUTE_SECTION_VARS(google_malloc);
-ABSL_DECLARE_ATTRIBUTE_SECTION_VARS(google_malloc);
-// actual functions are in debugallocation.cc or tcmalloc.cc
ABSL_DEFINE_ATTRIBUTE_SECTION_VARS(malloc_hook);
ABSL_DECLARE_ATTRIBUTE_SECTION_VARS(malloc_hook);
// actual functions are in this file, malloc_hook.cc, and low_level_alloc.cc
+ABSL_DEFINE_ATTRIBUTE_SECTION_VARS(google_malloc);
+ABSL_DECLARE_ATTRIBUTE_SECTION_VARS(google_malloc);
ABSL_DEFINE_ATTRIBUTE_SECTION_VARS(blink_malloc);
ABSL_DECLARE_ATTRIBUTE_SECTION_VARS(blink_malloc);
-// actual functions are in third_party/blink_headless/.../{PartitionAlloc,
-// FastMalloc}.cpp.
#define ADDR_IN_ATTRIBUTE_SECTION(addr, name) \
(reinterpret_cast<uintptr_t>(ABSL_ATTRIBUTE_SECTION_START(name)) <= \
@@ -486,13 +483,6 @@ static inline bool InHookCaller(const void* caller) {
static absl::once_flag in_hook_caller_once;
static void InitializeInHookCaller() {
- ABSL_INIT_ATTRIBUTE_SECTION_VARS(google_malloc);
- if (ABSL_ATTRIBUTE_SECTION_START(google_malloc) ==
- ABSL_ATTRIBUTE_SECTION_STOP(google_malloc)) {
- ABSL_RAW_LOG(ERROR,
- "google_malloc section is missing, "
- "thus InHookCaller is broken!");
- }
ABSL_INIT_ATTRIBUTE_SECTION_VARS(malloc_hook);
if (ABSL_ATTRIBUTE_SECTION_START(malloc_hook) ==
ABSL_ATTRIBUTE_SECTION_STOP(malloc_hook)) {
@@ -500,9 +490,14 @@ static void InitializeInHookCaller() {
"malloc_hook section is missing, "
"thus InHookCaller is broken!");
}
+ ABSL_INIT_ATTRIBUTE_SECTION_VARS(google_malloc);
+ if (ABSL_ATTRIBUTE_SECTION_START(google_malloc) ==
+ ABSL_ATTRIBUTE_SECTION_STOP(google_malloc)) {
+ ABSL_RAW_LOG(ERROR,
+ "google_malloc section is missing, "
+ "thus InHookCaller is broken!");
+ }
ABSL_INIT_ATTRIBUTE_SECTION_VARS(blink_malloc);
- // The blink_malloc section is only expected to be present in binaries
- // linking against the blink rendering engine in third_party/blink_headless.
}
// We can improve behavior/compactness of this function
@@ -574,7 +569,8 @@ extern "C" int MallocHook_GetCallerStackTrace(
// still allow users to disable this in special cases that can't be easily
// detected during compilation, via -DABSL_MALLOC_HOOK_MMAP_DISABLE or #define
// ABSL_MALLOC_HOOK_MMAP_DISABLE.
-// TODO(b/62370839): Remove MALLOC_HOOK_MMAP_DISABLE in CROSSTOOL for tsan and
+//
+// TODO(absl-team): Remove MALLOC_HOOK_MMAP_DISABLE in CROSSTOOL for tsan and
// msan config; Replace MALLOC_HOOK_MMAP_DISABLE with
// ABSL_MALLOC_HOOK_MMAP_DISABLE for other special cases.
#if !defined(THREAD_SANITIZER) && !defined(MEMORY_SANITIZER) && \
diff --git a/absl/base/internal/raw_logging.cc b/absl/base/internal/raw_logging.cc
index c0890614..1b849abf 100644
--- a/absl/base/internal/raw_logging.cc
+++ b/absl/base/internal/raw_logging.cc
@@ -34,10 +34,10 @@
//
// This preprocessor token is also defined in raw_io.cc. If you need to copy
// this, consider moving both to config.h instead.
-#if defined(__linux__) || defined(__APPLE__) || defined(__Fuchsia__) || \
- defined(__GENCLAVE__)
+#if defined(__linux__) || defined(__APPLE__) || defined(__Fuchsia__)
#include <unistd.h>
+
#define ABSL_HAVE_POSIX_WRITE 1
#define ABSL_LOW_LEVEL_WRITE_SUPPORTED 1
#else
@@ -110,10 +110,6 @@ namespace {
// CAVEAT: vsnprintf called from *DoRawLog below has some (exotic) code paths
// that invoke malloc() and getenv() that might acquire some locks.
-// If this becomes a problem we should reimplement a subset of vsnprintf
-// that does not need locks and malloc.
-// E.g. google3/third_party/clearsilver/core/util/snprintf.c
-// looks like such a reimplementation.
// Helper for RawLog below.
// *DoRawLog writes to *buf of *size and move them past the written portion.
diff --git a/absl/base/internal/scheduling_mode.h b/absl/base/internal/scheduling_mode.h
index b7560f30..1b6497ad 100644
--- a/absl/base/internal/scheduling_mode.h
+++ b/absl/base/internal/scheduling_mode.h
@@ -12,8 +12,8 @@
// See the License for the specific language governing permissions and
// limitations under the License.
//
-// Core interfaces and definitions used by by low-level //base interfaces such
-// as SpinLock.
+// Core interfaces and definitions used by by low-level interfaces such as
+// SpinLock.
#ifndef ABSL_BASE_INTERNAL_SCHEDULING_MODE_H_
#define ABSL_BASE_INTERNAL_SCHEDULING_MODE_H_
diff --git a/absl/base/internal/spinlock_wait.h b/absl/base/internal/spinlock_wait.h
index 6734cc9e..5f658211 100644
--- a/absl/base/internal/spinlock_wait.h
+++ b/absl/base/internal/spinlock_wait.h
@@ -18,10 +18,6 @@
// Operations to make atomic transitions on a word, and to allow
// waiting for those transitions to become possible.
-// This file is used internally in spinlock.cc and once.cc, and a few other
-// places listing in //base:spinlock_wait_users. If you need to use it outside
-// of //base, please request permission to be added to that list.
-
#include <stdint.h>
#include <atomic>
diff --git a/absl/base/internal/sysinfo.cc b/absl/base/internal/sysinfo.cc
index 6a4c0064..9e0140fa 100644
--- a/absl/base/internal/sysinfo.cc
+++ b/absl/base/internal/sysinfo.cc
@@ -57,10 +57,7 @@ static int num_cpus = 0;
static double nominal_cpu_frequency = 1.0; // 0.0 might be dangerous.
static int GetNumCPUs() {
-#if defined(__myriad2__) || defined(__GENCLAVE__)
- // TODO(b/28296132): Calling std::thread::hardware_concurrency() induces a
- // link error on myriad2 builds.
- // TODO(b/62709537): Support std::thread::hardware_concurrency() in gEnclalve.
+#if defined(__myriad2__)
return 1;
#else
// Other possibilities:
diff --git a/absl/base/internal/sysinfo.h b/absl/base/internal/sysinfo.h
index f21de143..5bd1c500 100644
--- a/absl/base/internal/sysinfo.h
+++ b/absl/base/internal/sysinfo.h
@@ -40,8 +40,7 @@ namespace base_internal {
// Thread-safe.
double NominalCPUFrequency();
-// Number of logical processors (hyperthreads) in system. See
-// //base/cpuid/cpuid.h for more CPU-related info. Thread-safe.
+// Number of logical processors (hyperthreads) in system. Thread-safe.
int NumCPUs();
// Return the thread id of the current thread, as told by the system.
diff --git a/absl/base/internal/sysinfo_test.cc b/absl/base/internal/sysinfo_test.cc
index 4c7d66b7..e0d9aab9 100644
--- a/absl/base/internal/sysinfo_test.cc
+++ b/absl/base/internal/sysinfo_test.cc
@@ -41,11 +41,10 @@ TEST(SysinfoTest, NominalCPUFrequency) {
EXPECT_GE(NominalCPUFrequency(), 1000.0)
<< "NominalCPUFrequency() did not return a reasonable value";
#else
- // TODO(b/37919252): Aarch64 cannot read the CPU frequency from sysfs, so we
+ // TODO(absl-team): Aarch64 cannot read the CPU frequency from sysfs, so we
// get back 1.0. Fix once the value is available.
EXPECT_EQ(NominalCPUFrequency(), 1.0)
- << "CPU frequency detection was fixed! Please update unittest and "
- "b/37919252";
+ << "CPU frequency detection was fixed! Please update unittest.";
#endif
}
diff --git a/absl/base/internal/thread_identity.cc b/absl/base/internal/thread_identity.cc
index ee96a588..678e8568 100644
--- a/absl/base/internal/thread_identity.cc
+++ b/absl/base/internal/thread_identity.cc
@@ -48,12 +48,10 @@ void AllocateThreadIdentityKey(ThreadIdentityReclaimerFunction reclaimer) {
ABSL_THREAD_IDENTITY_MODE == ABSL_THREAD_IDENTITY_MODE_USE_CPP11
// The actual TLS storage for a thread's currently associated ThreadIdentity.
// This is referenced by inline accessors in the header.
-// "protected" visibility ensures that if multiple copies of //base exist in a
-// process (via dlopen() or similar), references to
-// thread_identity_ptr from each copy of the code will refer to
-// *different* instances of this ptr. See extensive discussion of this choice
-// in cl/90634708
-// TODO(ahh): hard deprecate multiple copies of //base; remove this.
+// "protected" visibility ensures that if multiple instances of Abseil code
+// exist within a process (via dlopen() or similar), references to
+// thread_identity_ptr from each instance of the code will refer to
+// *different* instances of this ptr.
#ifdef __GNUC__
__attribute__((visibility("protected")))
#endif // __GNUC__
@@ -70,7 +68,6 @@ void SetCurrentThreadIdentity(
// NOTE: Not async-safe. But can be open-coded.
absl::call_once(init_thread_identity_key_once, AllocateThreadIdentityKey,
reclaimer);
- // b/18366710:
// We must mask signals around the call to setspecific as with current glibc,
// a concurrent getspecific (needed for GetCurrentThreadIdentityIfPresent())
// may zero our value.