12bc53e031
-- c99f979ad34f155fbeeea69b88bdc7458d89a21c by Derek Mauro <dmauro@google.com>: Remove a floating point division by zero test. This isn't testing behavior related to the library, and MSVC warns about it in opt mode. PiperOrigin-RevId: 285220804 -- 68b015491f0dbf1ab547994673281abd1f34cd4b by Gennadiy Rozental <rogeeff@google.com>: This CL introduces following changes to the class FlagImpl: * We eliminate the CommandLineFlagLocks struct. Instead callback guard and callback function are combined into a single CallbackData struct, while primary data lock is stored separately. * CallbackData member of class FlagImpl is initially set to be nullptr and is only allocated and initialized when a flag's callback is being set. For most flags we do not pay for the extra space and extra absl::Mutex now. * Primary data guard is stored in data_guard_ data member. This is a properly aligned character buffer of necessary size. During initialization of the flag we construct absl::Mutex in this space using placement new call. * We now avoid extra value copy after successful attempt to parse value out of string. Instead we swap flag's current value with tentative value we just produced. PiperOrigin-RevId: 285132636 -- ed45d118fb818969eb13094cf7827c885dfc562c by Tom Manshreck <shreck@google.com>: Change null-term* (and nul-term*) to NUL-term* in comments PiperOrigin-RevId: 285036610 -- 729619017944db895ce8d6d29c1995aa2e5628a5 by Derek Mauro <dmauro@google.com>: Use the Posix implementation of thread identity on MinGW. Some versions of MinGW suffer from thread_local bugs. PiperOrigin-RevId: 285022920 -- 39a25493503c76885bc3254c28f66a251c5b5bb0 by Greg Falcon <gfalcon@google.com>: Implementation detail change. Add further ABSL_NAMESPACE_BEGIN and _END annotation macros to files in Abseil. PiperOrigin-RevId: 285012012 GitOrigin-RevId: c99f979ad34f155fbeeea69b88bdc7458d89a21c Change-Id: I4c85d3704e45d11a9ac50d562f39640a6adbedc1
85 lines
3.3 KiB
C++
85 lines
3.3 KiB
C++
// Copyright 2017 The Abseil Authors.
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// https://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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//
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// Produces a stack trace for Windows. Normally, one could use
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// stacktrace_x86-inl.h or stacktrace_x86_64-inl.h -- and indeed, that
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// should work for binaries compiled using MSVC in "debug" mode.
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// However, in "release" mode, Windows uses frame-pointer
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// optimization, which makes getting a stack trace very difficult.
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//
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// There are several approaches one can take. One is to use Windows
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// intrinsics like StackWalk64. These can work, but have restrictions
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// on how successful they can be. Another attempt is to write a
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// version of stacktrace_x86-inl.h that has heuristic support for
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// dealing with FPO, similar to what WinDbg does (see
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// http://www.nynaeve.net/?p=97). There are (non-working) examples of
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// these approaches, complete with TODOs, in stacktrace_win32-inl.h#1
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//
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// The solution we've ended up doing is to call the undocumented
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// windows function RtlCaptureStackBackTrace, which probably doesn't
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// work with FPO but at least is fast, and doesn't require a symbol
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// server.
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//
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// This code is inspired by a patch from David Vitek:
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// https://code.google.com/p/google-perftools/issues/detail?id=83
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#ifndef ABSL_DEBUGGING_INTERNAL_STACKTRACE_WIN32_INL_H_
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#define ABSL_DEBUGGING_INTERNAL_STACKTRACE_WIN32_INL_H_
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#include <windows.h> // for GetProcAddress and GetModuleHandle
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#include <cassert>
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typedef USHORT NTAPI RtlCaptureStackBackTrace_Function(
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IN ULONG frames_to_skip,
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IN ULONG frames_to_capture,
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OUT PVOID *backtrace,
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OUT PULONG backtrace_hash);
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// Load the function we need at static init time, where we don't have
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// to worry about someone else holding the loader's lock.
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static RtlCaptureStackBackTrace_Function* const RtlCaptureStackBackTrace_fn =
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(RtlCaptureStackBackTrace_Function*)
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GetProcAddress(GetModuleHandleA("ntdll.dll"), "RtlCaptureStackBackTrace");
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template <bool IS_STACK_FRAMES, bool IS_WITH_CONTEXT>
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static int UnwindImpl(void** result, int* sizes, int max_depth, int skip_count,
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const void*, int* min_dropped_frames) {
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int n = 0;
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if (!RtlCaptureStackBackTrace_fn) {
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// can't find a stacktrace with no function to call
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} else {
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n = (int)RtlCaptureStackBackTrace_fn(skip_count + 2, max_depth, result, 0);
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}
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if (IS_STACK_FRAMES) {
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// No implementation for finding out the stack frame sizes yet.
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memset(sizes, 0, sizeof(*sizes) * n);
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}
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if (min_dropped_frames != nullptr) {
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// Not implemented.
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*min_dropped_frames = 0;
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}
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return n;
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}
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namespace absl {
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ABSL_NAMESPACE_BEGIN
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namespace debugging_internal {
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bool StackTraceWorksForTest() {
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return false;
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}
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} // namespace debugging_internal
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ABSL_NAMESPACE_END
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} // namespace absl
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#endif // ABSL_DEBUGGING_INTERNAL_STACKTRACE_WIN32_INL_H_
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