X-Git-Url: http://plrg.eecs.uci.edu/git/?a=blobdiff_plain;f=folly%2Fdetail%2FThreadLocalDetail.h;h=6769410be67e6ff3b4d6317abc5727330f488963;hb=320a9600f9cb11bbfd3f17dc99cb7b252132eb37;hp=0c05802c63804b1d75419ee082282cbc7b7d5be8;hpb=81fa7fd7ac3de80e645dae5243987f05049627b5;p=folly.git

diff --git a/folly/detail/ThreadLocalDetail.h b/folly/detail/ThreadLocalDetail.h
index 0c05802c..6769410b 100644
--- a/folly/detail/ThreadLocalDetail.h
+++ b/folly/detail/ThreadLocalDetail.h
@@ -1,5 +1,5 @@
 /*
- * Copyright 2014 Facebook, Inc.
+ * Copyright 2015 Facebook, Inc.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -30,6 +30,18 @@
 #include <folly/Exception.h>
 #include <folly/Malloc.h>
 
+// In general, emutls cleanup is not guaranteed to play nice with the way
+// StaticMeta mixes direct pthread calls and the use of __thread. This has
+// caused problems on multiple platforms so don't use __thread there.
+//
+// XXX: Ideally we would instead determine if emutls is in use at runtime as it
+// is possible to configure glibc on Linux to use emutls regardless.
+#if !__APPLE__ && !__ANDROID__
+#define FOLLY_TLD_USE_FOLLY_TLS 1
+#else
+#undef FOLLY_TLD_USE_FOLLY_TLS
+#endif
+
 namespace folly {
 namespace threadlocal_detail {
 
@@ -166,8 +178,8 @@ struct StaticMeta {
     return *inst_;
   }
 
-  int nextId_;
-  std::vector<int> freeIds_;
+  uint32_t nextId_;
+  std::vector<uint32_t> freeIds_;
   std::mutex lock_;
   pthread_key_t pthreadKey_;
   ThreadEntry head_;
@@ -185,7 +197,7 @@ struct StaticMeta {
     t->next = t->prev = t;
   }
 
-#if !__APPLE__
+#ifdef FOLLY_TLD_USE_FOLLY_TLS
   static FOLLY_TLS ThreadEntry threadEntry_;
 #endif
   static StaticMeta<Tag>* inst_;
@@ -195,14 +207,18 @@ struct StaticMeta {
     int ret = pthread_key_create(&pthreadKey_, &onThreadExit);
     checkPosixError(ret, "pthread_key_create failed");
 
-    // pthread_atfork is not part of the Android NDK at least as of n9d. If
-    // something is trying to call native fork() directly at all with Android's
-    // process management model, this is probably the least of the problems.
-#if !__ANDROID__
+#if FOLLY_HAVE_PTHREAD_ATFORK
     ret = pthread_atfork(/*prepare*/ &StaticMeta::preFork,
                          /*parent*/ &StaticMeta::onForkParent,
                          /*child*/ &StaticMeta::onForkChild);
     checkPosixError(ret, "pthread_atfork failed");
+#elif !__ANDROID__
+    // pthread_atfork is not part of the Android NDK at least as of n9d. If
+    // something is trying to call native fork() directly at all with Android's
+    // process management model, this is probably the least of the problems.
+    //
+    // But otherwise, this is a problem.
+    #warning pthread_atfork unavailable
 #endif
   }
   ~StaticMeta() {
@@ -210,7 +226,7 @@ struct StaticMeta {
   }
 
   static ThreadEntry* getThreadEntry() {
-#if !__APPLE__
+#ifdef FOLLY_TLD_USE_FOLLY_TLS
     return &threadEntry_;
 #else
     ThreadEntry* threadEntry =
@@ -245,7 +261,7 @@ struct StaticMeta {
 
   static void onThreadExit(void* ptr) {
     auto& meta = instance();
-#if !__APPLE__
+#ifdef FOLLY_TLD_USE_FOLLY_TLS
     ThreadEntry* threadEntry = getThreadEntry();
 
     DCHECK_EQ(ptr, &meta);
@@ -275,14 +291,14 @@ struct StaticMeta {
     threadEntry->elements = nullptr;
     pthread_setspecific(meta.pthreadKey_, nullptr);
 
-#if __APPLE__
-    // Allocated in getThreadEntry(); free it
+#ifndef FOLLY_TLD_USE_FOLLY_TLS
+    // Allocated in getThreadEntry() when not using folly TLS; free it
     delete threadEntry;
 #endif
   }
 
-  static int create() {
-    int id;
+  static uint32_t create() {
+    uint32_t id;
     auto & meta = instance();
     std::lock_guard<std::mutex> g(meta.lock_);
     if (!meta.freeIds_.empty()) {
@@ -294,7 +310,7 @@ struct StaticMeta {
     return id;
   }
 
-  static void destroy(size_t id) {
+  static void destroy(uint32_t id) {
     try {
       auto & meta = instance();
       // Elements in other threads that use this id.
@@ -336,7 +352,7 @@ struct StaticMeta {
    * Reserve enough space in the ThreadEntry::elements for the item
    * @id to fit in.
    */
-  static void reserve(int id) {
+  static void reserve(uint32_t id) {
     auto& meta = instance();
     ThreadEntry* threadEntry = getThreadEntry();
     size_t prevCapacity = threadEntry->elementsCapacity;
@@ -415,14 +431,14 @@ struct StaticMeta {
 
     free(reallocated);
 
-#if !__APPLE__
+#ifdef FOLLY_TLD_USE_FOLLY_TLS
     if (prevCapacity == 0) {
       pthread_setspecific(meta.pthreadKey_, &meta);
     }
 #endif
   }
 
-  static ElementWrapper& get(size_t id) {
+  static ElementWrapper& get(uint32_t id) {
     ThreadEntry* threadEntry = getThreadEntry();
     if (UNLIKELY(threadEntry->elementsCapacity <= id)) {
       reserve(id);
@@ -432,7 +448,7 @@ struct StaticMeta {
   }
 };
 
-#if !__APPLE__
+#ifdef FOLLY_TLD_USE_FOLLY_TLS
 template <class Tag>
 FOLLY_TLS ThreadEntry StaticMeta<Tag>::threadEntry_{nullptr, 0,
                                                     nullptr, nullptr};