Thread::getTid returns pid_t gettid() after run
This is needed when the parent or any other thread besides the child
needs access to the child's kernel tid.
Change-Id: Ib148505913eb78314cfd76657c30d7b20663dffd
diff --git a/libs/utils/Threads.cpp b/libs/utils/Threads.cpp
index e343c62..ab207f5 100644
--- a/libs/utils/Threads.cpp
+++ b/libs/utils/Threads.cpp
@@ -34,6 +34,9 @@
# include <pthread.h>
# include <sched.h>
# include <sys/resource.h>
+#ifdef HAVE_ANDROID_OS
+# include <bionic_pthread.h>
+#endif
#elif defined(HAVE_WIN32_THREADS)
# include <windows.h>
# include <stdint.h>
@@ -86,7 +89,7 @@
char * threadName;
// we use this trampoline when we need to set the priority with
- // nice/setpriority.
+ // nice/setpriority, and name with prctl.
static int trampoline(const thread_data_t* t) {
thread_func_t f = t->entryFunction;
void* u = t->userData;
@@ -141,8 +144,13 @@
#ifdef HAVE_ANDROID_OS /* valgrind is rejecting RT-priority create reqs */
if (threadPriority != PRIORITY_DEFAULT || threadName != NULL) {
- // We could avoid the trampoline if there was a way to get to the
- // android_thread_id_t (pid) from pthread_t
+ // Now that the pthread_t has a method to find the associated
+ // android_thread_id_t (pid) from pthread_t, it would be possible to avoid
+ // this trampoline in some cases as the parent could set the properties
+ // for the child. However, there would be a race condition because the
+ // child becomes ready immediately, and it doesn't work for the name.
+ // prctl(PR_SET_NAME) only works for self; prctl(PR_SET_THREAD_NAME) was
+ // proposed but not yet accepted.
thread_data_t* t = new thread_data_t;
t->priority = threadPriority;
t->threadName = threadName ? strdup(threadName) : NULL;
@@ -178,6 +186,13 @@
return 1;
}
+#ifdef HAVE_ANDROID_OS
+static pthread_t android_thread_id_t_to_pthread(android_thread_id_t thread)
+{
+ return (pthread_t) thread;
+}
+#endif
+
android_thread_id_t androidGetThreadId()
{
return (android_thread_id_t)pthread_self();
@@ -909,6 +924,23 @@
return mStatus;
}
+#ifdef HAVE_ANDROID_OS
+pid_t Thread::getTid() const
+{
+ // mTid is not defined until the child initializes it, and the caller may need it earlier
+ Mutex::Autolock _l(mLock);
+ pid_t tid;
+ if (mRunning) {
+ pthread_t pthread = android_thread_id_t_to_pthread(mThread);
+ tid = __pthread_gettid(pthread);
+ } else {
+ ALOGW("Thread (this=%p): getTid() is undefined before run()", this);
+ tid = -1;
+ }
+ return tid;
+}
+#endif
+
bool Thread::exitPending() const
{
Mutex::Autolock _l(mLock);