/usr/include/mozjs-38/mozilla/ThreadLocal.h is in libmozjs-38-dev 38.8.0~repack1-0ubuntu4.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
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/* vim: set ts=8 sts=2 et sw=2 tw=80: */
/* This Source Code Form is subject to the terms of the Mozilla Public
* License, v. 2.0. If a copy of the MPL was not distributed with this
* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
/* Cross-platform lightweight thread local data wrappers. */
#ifndef mozilla_ThreadLocal_h
#define mozilla_ThreadLocal_h
#if defined(XP_WIN)
// This file will get included in any file that wants to add a profiler mark.
// In order to not bring <windows.h> together we could include windef.h and
// winbase.h which are sufficient to get the prototypes for the Tls* functions.
// # include <windef.h>
// # include <winbase.h>
// Unfortunately, even including these headers causes us to add a bunch of ugly
// stuff to our namespace e.g #define CreateEvent CreateEventW
extern "C" {
__declspec(dllimport) void* __stdcall TlsGetValue(unsigned long);
__declspec(dllimport) int __stdcall TlsSetValue(unsigned long, void*);
__declspec(dllimport) unsigned long __stdcall TlsAlloc();
}
#else
# include <pthread.h>
# include <signal.h>
#endif
#include "mozilla/Assertions.h"
#include "mozilla/Attributes.h"
#include "mozilla/TypeTraits.h"
namespace mozilla {
// sig_safe_t denotes an atomic type which can be read or stored in a single
// instruction. This means that data of this type is safe to be manipulated
// from a signal handler, or other similar asynchronous execution contexts.
#if defined(XP_WIN)
typedef unsigned long sig_safe_t;
#else
typedef sig_atomic_t sig_safe_t;
#endif
/*
* Thread Local Storage helpers.
*
* Usage:
*
* Only static-storage-duration (e.g. global variables, or static class members)
* objects of this class should be instantiated. This class relies on
* zero-initialization, which is implicit for static-storage-duration objects.
* It doesn't have a custom default constructor, to avoid static initializers.
*
* API usage:
*
* // Create a TLS item.
* //
* // Note that init() should be invoked exactly once, before any usage of set()
* // or get().
* mozilla::ThreadLocal<int> tlsKey;
* if (!tlsKey.init()) {
* // deal with the error
* }
*
* // Set the TLS value
* tlsKey.set(123);
*
* // Get the TLS value
* int value = tlsKey.get();
*/
template<typename T>
class ThreadLocal
{
#if defined(XP_WIN)
typedef unsigned long key_t;
#else
typedef pthread_key_t key_t;
#endif
// Integral types narrower than void* must be extended to avoid
// warnings from valgrind on some platforms. This helper type
// achieves that without penalizing the common case of ThreadLocals
// instantiated using a pointer type.
template<typename S>
struct Helper
{
typedef uintptr_t Type;
};
template<typename S>
struct Helper<S *>
{
typedef S *Type;
};
public:
MOZ_WARN_UNUSED_RESULT inline bool init();
inline T get() const;
inline void set(const T aValue);
bool initialized() const { return mInited; }
private:
key_t mKey;
bool mInited;
};
template<typename T>
inline bool
ThreadLocal<T>::init()
{
static_assert(mozilla::IsPointer<T>::value || mozilla::IsIntegral<T>::value,
"mozilla::ThreadLocal must be used with a pointer or "
"integral type");
static_assert(sizeof(T) <= sizeof(void*),
"mozilla::ThreadLocal can't be used for types larger than "
"a pointer");
MOZ_ASSERT(!initialized());
#ifdef XP_WIN
mKey = TlsAlloc();
mInited = mKey != 0xFFFFFFFFUL; // TLS_OUT_OF_INDEXES
#else
mInited = !pthread_key_create(&mKey, nullptr);
#endif
return mInited;
}
template<typename T>
inline T
ThreadLocal<T>::get() const
{
MOZ_ASSERT(initialized());
void* h;
#ifdef XP_WIN
h = TlsGetValue(mKey);
#else
h = pthread_getspecific(mKey);
#endif
return static_cast<T>(reinterpret_cast<typename Helper<T>::Type>(h));
}
template<typename T>
inline void
ThreadLocal<T>::set(const T aValue)
{
MOZ_ASSERT(initialized());
void* h = reinterpret_cast<void*>(static_cast<typename Helper<T>::Type>(aValue));
#ifdef XP_WIN
bool succeeded = TlsSetValue(mKey, h);
#else
bool succeeded = !pthread_setspecific(mKey, h);
#endif
if (!succeeded) {
MOZ_CRASH();
}
}
} // namespace mozilla
#endif /* mozilla_ThreadLocal_h */
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