From d18051870e8e2a5f55237a2c11fde75f46082639 Mon Sep 17 00:00:00 2001
From: Jeff Brown <jeffbrown@google.com>
Date: Tue, 21 Sep 2010 15:11:18 -0700
Subject: [PATCH] Looper: use pthread_once for TLS key initialization.

Also fix a Valgrind complaint by zeroing out the entire epoll event
struct since otherwise the data field union would be partly
uninitialized (but not in a harmful way).

Change-Id: I2091ce517e87fcad7c9caf90e2c5e4854a7ca465
---
 include/utils/Looper.h |  1 +
 libs/utils/Looper.cpp  | 29 ++++++++++++++---------------
 2 files changed, 15 insertions(+), 15 deletions(-)

diff --git a/include/utils/Looper.h b/include/utils/Looper.h
index 7d908669e..3f00b788c 100644
--- a/include/utils/Looper.h
+++ b/include/utils/Looper.h
@@ -205,6 +205,7 @@ private:
 
     int pollInner(int timeoutMillis);
 
+    static void initTLSKey();
     static void threadDestructor(void *st);
 };
 
diff --git a/libs/utils/Looper.cpp b/libs/utils/Looper.cpp
index b46279efc..d2dd6eb48 100644
--- a/libs/utils/Looper.cpp
+++ b/libs/utils/Looper.cpp
@@ -24,16 +24,15 @@
 
 namespace android {
 
-static pthread_mutex_t gTLSMutex = PTHREAD_MUTEX_INITIALIZER;
-static bool gHaveTLS = false;
-static pthread_key_t gTLS = 0;
-
 // Hint for number of file descriptors to be associated with the epoll instance.
 static const int EPOLL_SIZE_HINT = 8;
 
 // Maximum number of file descriptors for which to retrieve poll events each iteration.
 static const int EPOLL_MAX_EVENTS = 16;
 
+static pthread_once_t gTLSOnce = PTHREAD_ONCE_INIT;
+static pthread_key_t gTLSKey = 0;
+
 Looper::Looper(bool allowNonCallbacks) :
         mAllowNonCallbacks(allowNonCallbacks),
         mResponseIndex(0) {
@@ -56,6 +55,7 @@ Looper::Looper(bool allowNonCallbacks) :
             errno);
 
     struct epoll_event eventItem;
+    memset(& eventItem, 0, sizeof(epoll_event)); // zero out unused members of data field union
     eventItem.events = EPOLLIN;
     eventItem.data.fd = mWakeReadPipeFd;
     result = epoll_ctl(mEpollFd, EPOLL_CTL_ADD, mWakeReadPipeFd, & eventItem);
@@ -69,6 +69,11 @@ Looper::~Looper() {
     close(mEpollFd);
 }
 
+void Looper::initTLSKey() {
+    int result = pthread_key_create(& gTLSKey, threadDestructor);
+    LOG_ALWAYS_FATAL_IF(result != 0, "Could not allocate TLS key.");
+}
+
 void Looper::threadDestructor(void *st) {
     Looper* const self = static_cast<Looper*>(st);
     if (self != NULL) {
@@ -83,7 +88,7 @@ void Looper::setForThread(const sp<Looper>& looper) {
         looper->incStrong((void*)threadDestructor);
     }
 
-    pthread_setspecific(gTLS, looper.get());
+    pthread_setspecific(gTLSKey, looper.get());
 
     if (old != NULL) {
         old->decStrong((void*)threadDestructor);
@@ -91,17 +96,10 @@ void Looper::setForThread(const sp<Looper>& looper) {
 }
 
 sp<Looper> Looper::getForThread() {
-    if (!gHaveTLS) {
-        pthread_mutex_lock(&gTLSMutex);
-        if (pthread_key_create(&gTLS, threadDestructor) != 0) {
-            pthread_mutex_unlock(&gTLSMutex);
-            return NULL;
-        }
-        gHaveTLS = true;
-        pthread_mutex_unlock(&gTLSMutex);
-    }
+    int result = pthread_once(& gTLSOnce, initTLSKey);
+    LOG_ALWAYS_FATAL_IF(result != 0, "pthread_once failed");
 
-    return (Looper*)pthread_getspecific(gTLS);
+    return (Looper*)pthread_getspecific(gTLSKey);
 }
 
 sp<Looper> Looper::prepare(int opts) {
@@ -331,6 +329,7 @@ int Looper::addFd(int fd, int ident, int events, ALooper_callbackFunc callback,
         request.data = data;
 
         struct epoll_event eventItem;
+        memset(& eventItem, 0, sizeof(epoll_event)); // zero out unused members of data field union
         eventItem.events = epollEvents;
         eventItem.data.fd = fd;