platform_system_core/libcutils/threads.cpp

/*
** Copyright (C) 2007, The Android Open Source Project
**
** Licensed under the Apache License, Version 2.0 (the "License");
** you may not use this file except in compliance with the License.
** You may obtain a copy of the License at
**
**     http://www.apache.org/licenses/LICENSE-2.0
**
** Unless required by applicable law or agreed to in writing, software
** distributed under the License is distributed on an "AS IS" BASIS,
** WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
** See the License for the specific language governing permissions and
** limitations under the License.
*/

#include <cutils/threads.h>

// For gettid.
#if defined(__APPLE__)
#include "AvailabilityMacros.h"  // For MAC_OS_X_VERSION_MAX_ALLOWED
#include <stdint.h>
#include <stdlib.h>
#include <sys/syscall.h>
#include <sys/time.h>
#include <unistd.h>
#elif defined(__linux__) && !defined(__ANDROID__)
#include <syscall.h>
#include <unistd.h>
#elif defined(_WIN32)
#include <windows.h>
#endif

// No definition needed for Android because we'll just pick up bionic's copy.
#ifndef __ANDROID__
pid_t gettid() {
#if defined(__APPLE__)
  uint64_t tid;
  pthread_threadid_np(NULL, &tid);
  return tid;
#elif defined(__linux__)
  return syscall(__NR_gettid);
#elif defined(_WIN32)
  return GetCurrentThreadId();
#endif
}
#endif  // __ANDROID__

#if !defined(_WIN32)

void*  thread_store_get( thread_store_t*  store )
{
    if (!store->has_tls)
        return NULL;

    return pthread_getspecific( store->tls );
}

extern void   thread_store_set( thread_store_t*          store,
                                void*                    value,
                                thread_store_destruct_t  destroy)
{
    pthread_mutex_lock( &store->lock );
    if (!store->has_tls) {
        if (pthread_key_create( &store->tls, destroy) != 0) {
            pthread_mutex_unlock(&store->lock);
            return;
        }
        store->has_tls = 1;
    }
    pthread_mutex_unlock( &store->lock );

    pthread_setspecific( store->tls, value );
}

#else /* !defined(_WIN32) */
void*  thread_store_get( thread_store_t*  store )
{
    if (!store->has_tls)
        return NULL;

    return (void*) TlsGetValue( store->tls );
}

void   thread_store_set( thread_store_t*          store,
                         void*                    value,
                         thread_store_destruct_t  /*destroy*/ )
{
    /* XXX: can't use destructor on thread exit */
    if (!store->lock_init) {
        store->lock_init = -1;
        InitializeCriticalSection( &store->lock );
        store->lock_init = -2;
    } else while (store->lock_init != -2) {
        Sleep(10); /* 10ms */
    }

    EnterCriticalSection( &store->lock );
    if (!store->has_tls) {
        store->tls = TlsAlloc();
        if (store->tls == TLS_OUT_OF_INDEXES) {
            LeaveCriticalSection( &store->lock );
            return;
        }
        store->has_tls = 1;
    }
    LeaveCriticalSection( &store->lock );

    TlsSetValue( store->tls, value );
}
#endif /* !defined(_WIN32) */