Added labelled thread names to help with some debugging activity. Right now,...

src/platform-macos.cc

Index: src/platform-macos.cc
===================================================================
--- src/platform-macos.cc	(revision 6139)
+++ src/platform-macos.cc	(working copy)
@@ -28,6 +28,8 @@
 // Platform specific code for MacOS goes here. For the POSIX comaptible parts
 // the implementation is in platform-posix.cc.
 
+#include <dlfcn.h>
+#include <string>
 #include <unistd.h>
 #include <sys/mman.h>
 #include <mach/mach_init.h>
@@ -411,25 +413,55 @@
 
 
 Thread::Thread() : ThreadHandle(ThreadHandle::INVALID) {
+  set_name("v8:<unknown>");
 }
 
 
+Thread::Thread(const char* name) : ThreadHandle(ThreadHandle::INVALID) {
+  set_name(name);
+}
+
+
 Thread::~Thread() {
 }
 
 
+
+static void SetThreadName(const char* name) {
+  // pthread_setname_np is only available in 10.6 or later, so test
+  // for it at runtime.
+  int (*dynamic_pthread_setname_np)(const char*);
+  *reinterpret_cast<void**>(&dynamic_pthread_setname_np) =
+    dlsym(RTLD_DEFAULT, "pthread_setname_np");
+  if (!dynamic_pthread_setname_np)
+    return;
+
+  // Mac OS X does not expose the length limit of the name, so hardcode it.
+  const int kMaxNameLength = 63;
+  std::string shortened_name = std::string(name).substr(0, kMaxNameLength);
+  dynamic_pthread_setname_np(shortened_name.c_str());
+}
+
+
 static void* ThreadEntry(void* arg) {
   Thread* thread = reinterpret_cast<Thread*>(arg);
   // This is also initialized by the first argument to pthread_create() but we
   // don't know which thread will run first (the original thread or the new
   // one) so we initialize it here too.
   thread->thread_handle_data()->thread_ = pthread_self();
+  SetThreadName(thread->name());
   ASSERT(thread->IsValid());
   thread->Run();
   return NULL;
 }
 
 
+void Thread::set_name(const char* name) {
+  strncpy(name_, name, sizeof(name_));
+  name_[sizeof(name_) - 1] = '\0';
+}
+
+
 void Thread::Start() {
   pthread_create(&thread_handle_data()->thread_, NULL, ThreadEntry, this);
 }