From 7f055c204a4371154123a1816fbec9855ee60ad5 Mon Sep 17 00:00:00 2001
From: Ian Lance Taylor <ian@airs.com>
Date: Tue, 24 Mar 2009 04:50:32 +0000
Subject: 2009-03-23  Ian Lance Taylor  <iant@google.com>

	* gold-threads.h (class Initialize_lock): Define.
	* gold-threads.cc (class Initialize_lock_once): Define.
	(initialize_lock_control): New static variable.
	(initialize_lock_pointer): New static variable.
	(initialize_lock_once): New static function.
	(Initialize_lock::Initialize_lock): Define.
	(Initialize_lock::initialize): Define.
	* target-select.h: Include "gold-threads.h".
	(class Target_selector): Add lock_ and initialize_lock_ fields.
	Don't define instantiate_target, just declare it.
	* target-select.cc (Target_selector::Target_selector): Initialize
	new fields.
	(Target_selector::instantiate_target): Define.
	* descriptors.h: Include "gold-threads.h".
	(class Descriptors): Add initialize_lock_ field.
	* descriptors.cc (Descriptors::Descriptors): Initialize new
	field.
	(Descriptors::open): Use initialize_lock_ field
	* errors.h (class Errors): Add initialize_lock_ field.
	* errors.cc (Errors::Errors): Initialize new field.
	(Errors::initialize_lock): Use initialize_lock_ field.
	* powerpc.cc (class Target_selector_powerpc): Remove
	instantiated_target_ field.  In do_recognize call
	instantiate_target rather than do_instantiate_target.  In
	do_instantiate_target just allocate a new target.
	* sparc.cc (class Target_selector_sparc): Likewise.
---
 gold/gold-threads.cc | 124 +++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 124 insertions(+)

(limited to 'gold/gold-threads.cc')

diff --git a/gold/gold-threads.cc b/gold/gold-threads.cc
index 9aa883d6cc..347170814d 100644
--- a/gold/gold-threads.cc
+++ b/gold/gold-threads.cc
@@ -276,4 +276,128 @@ Condvar::~Condvar()
   delete this->condvar_;
 }
 
+#ifdef ENABLE_THREADS
+
+// Class Initialize_lock_once.  This exists to hold a pthread_once_t
+// structure for Initialize_lock.
+
+class Initialize_lock_once
+{
+ public:
+  Initialize_lock_once()
+    : once_(PTHREAD_ONCE_INIT)
+  { }
+
+  // Return a pointer to the pthread_once_t variable.
+  pthread_once_t*
+  once_control()
+  { return &this->once_; }
+
+ private:
+  pthread_once_t once_;
+};
+
+#endif // !defined(ENABLE_THREADS)
+
+#ifdef ENABLE_THREADS
+
+// A single lock which controls access to initialize_lock_pointer.
+// This is used because we can't pass parameters to functions passed
+// to pthread_once.
+
+static pthread_mutex_t initialize_lock_control = PTHREAD_MUTEX_INITIALIZER;
+
+// A pointer to a pointer to the lock which we need to initialize
+// once.  Access to this is controlled by initialize_lock_pointer.
+
+static Lock** initialize_lock_pointer;
+
+// A routine passed to pthread_once which initializes the lock which
+// initialize_lock_pointer points to.
+
+extern "C"
+{
+
+static void
+initialize_lock_once()
+{
+  *initialize_lock_pointer = new Lock();
+}
+
+}
+
+#endif // !defined(ENABLE_THREADS)
+
+// Class Initialize_lock.
+
+Initialize_lock::Initialize_lock(Lock** pplock)
+  : pplock_(pplock)
+{
+#ifndef ENABLE_THREADS
+  this->once_ = NULL;
+#else
+  this->once_ = new Initialize_lock_once();
+#endif
+}
+
+// Initialize the lock.
+
+bool
+Initialize_lock::initialize()
+{
+  // If the lock has already been initialized, we don't need to do
+  // anything.  Note that this assumes that the pointer value will be
+  // set completely or not at all.  I hope this is always safe.  We
+  // want to do this for efficiency.
+  if (*this->pplock_ != NULL)
+    return true;
+
+  // We can't initialize the lock until we have read the options.
+  if (!parameters->options_valid())
+    return false;
+
+  // If the user did not use --threads, then we can initialize
+  // directly.
+  if (!parameters->options().threads())
+    {
+      *this->pplock_ = new Lock();
+      return true;
+    }
+
+#ifndef ENABLE_THREADS
+
+  // If there is no threads support, we don't need to use
+  // pthread_once.
+  *this->pplock_ = new Lock();
+
+#else // !defined(ENABLE_THREADS)
+
+  // Since we can't pass parameters to routines called by
+  // pthread_once, we use a static variable: initialize_lock_pointer.
+  // That in turns means that we need to use a mutex to control access
+  // to initialize_lock_pointer.
+
+  int err = pthread_mutex_lock(&initialize_lock_control);
+  if (err != 0)
+    gold_fatal(_("pthread_mutex_lock failed: %s"), strerror(err));
+
+  initialize_lock_pointer = this->pplock_;
+
+  err = pthread_once(this->once_->once_control(), initialize_lock_once);
+  if (err != 0)
+    gold_fatal(_("pthread_once failed: %s"), strerror(err));
+
+  initialize_lock_pointer = NULL;
+
+  err = pthread_mutex_unlock(&initialize_lock_control);
+  if (err != 0)
+    gold_fatal(_("pthread_mutex_unlock failed: %s"), strerror(err));
+
+  gold_assert(*this->pplock_ != NULL);
+
+#endif // !defined(ENABLE_THREADS)
+
+  return true;
+}
+
 } // End namespace gold.
-- 
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