From 97b8365cafc3a344a22d3980b8ed885f5c6d8357 Mon Sep 17 00:00:00 2001
From: Tom Tromey <tromey@gcc.gnu.org>
Date: Tue, 9 Jan 2007 19:58:05 +0000
Subject: Merged gcj-eclipse branch to trunk.

From-SVN: r120621
---
 libjava/java/lang/natThreadLocal.cc | 169 ++++++++++++++++++++++++++++++++++++
 1 file changed, 169 insertions(+)
 create mode 100644 libjava/java/lang/natThreadLocal.cc

(limited to 'libjava/java/lang/natThreadLocal.cc')

diff --git a/libjava/java/lang/natThreadLocal.cc b/libjava/java/lang/natThreadLocal.cc
new file mode 100644
index 0000000..cd61f4a
--- /dev/null
+++ b/libjava/java/lang/natThreadLocal.cc
@@ -0,0 +1,169 @@
+// natThreadLocal.cc - Native part of ThreadLocal class.
+
+// Fast thread local storage for systems that support the __thread
+// variable attribute.
+   
+/* Copyright (C) 2006  Free Software Foundation
+
+   This file is part of libgcj.
+
+This software is copyrighted work licensed under the terms of the
+Libgcj License.  Please consult the file "LIBGCJ_LICENSE" for
+details.  */
+
+#include <config.h>
+
+#include <stdlib.h>
+
+#include <gcj/cni.h>
+#include <jvm.h>
+#include <java-threads.h>
+
+#include <gnu/gcj/RawDataManaged.h>
+#include <java/lang/ThreadLocal.h>
+#include <java/lang/IllegalArgumentException.h>
+#include <java/lang/IllegalThreadStateException.h>
+#include <java/lang/InterruptedException.h>
+#include <java/util/Map.h>
+
+#include <jni.h>
+
+/* We would like to have fast thread local variables that behave in
+   the same way as C and C++ thread local variables.  This would mean
+   having an field attribute "thread" (like static, final, etc.).
+   However, this is not compatible with java semantics, which we wish
+   to support transparently.  The problems we must overcome are:
+
+   * In Java, ThreadLocal variables are not statically allocated: they
+     are objects, created at runtime.
+
+   * Class ThreadLocal is not final and neither are its methods, so it
+     is possible to create a subclass of ThreadLocal that overrides
+     any method.
+
+   * __thread variables in DSOs are not visible to the garbage
+     collector, so we must ensure that we keep a copy of every thread
+     local variable somewhere on the heap.
+
+   * Once a ThreadLocal instance has been created and assigned to a
+     static field, that field may be reassigned to a different
+     ThreadLocal instance or null.  
+
+   So, we can't simply replace get() and set() with accesses of a
+   __thread variable.
+
+   So, we create a pthread_key in each ThreadLocal object and use that
+   as a kind of "look-aside cache".  When a ThreadLocal is set, we
+   also set the corresponding thread-specific value.  When the
+   ThreadLocal is collected, we delete the key.
+
+   This scheme is biased towards efficiency when get() is called much
+   more frequently than set().  It is slightly internaler than the
+   all-Java solution using the underlying map in the set() case.
+   However, get() is very much more frequently invoked than set().
+
+*/
+
+
+#ifdef _POSIX_PTHREAD_SEMANTICS
+
+class tls_t
+{
+public:
+  pthread_key_t key;
+};
+
+void
+java::lang::ThreadLocal::constructNative (void)
+{
+  tls_t *tls = (tls_t *)_Jv_Malloc (sizeof (tls_t));
+  if (pthread_key_create (&tls->key, NULL) == 0)
+    TLSPointer = (::gnu::gcj::RawData *)tls;
+  else
+    _Jv_Free (tls);
+}
+
+void 
+java::lang::ThreadLocal::set (::java::lang::Object *value)
+{
+  if (TLSPointer != NULL)
+    {
+      tls_t* tls = (tls_t*)TLSPointer;
+      pthread_setspecific (tls->key, value);
+    } 
+
+  internalSet (value);
+}
+
+::java::lang::Object *
+java::lang::ThreadLocal::get (void)
+{
+  if (TLSPointer == NULL)
+    return internalGet ();
+
+  tls_t* tls = (tls_t*)TLSPointer;
+  void *obj = pthread_getspecific(tls->key);
+
+  if (obj)
+    return (::java::lang::Object *)obj;
+
+  ::java::lang::Object *value = internalGet ();
+  pthread_setspecific (tls->key, value);
+
+  return value;
+}
+
+void 
+java::lang::ThreadLocal::remove (void)
+{
+  if (TLSPointer != NULL)
+    {
+      tls_t* tls = (tls_t*)TLSPointer;
+      pthread_setspecific (tls->key, NULL);
+    }
+
+  internalRemove ();
+}
+
+void 
+java::lang::ThreadLocal::finalize (void)
+{
+  if (TLSPointer != NULL)
+    {
+      tls_t* tls = (tls_t*)TLSPointer;
+      pthread_key_delete (tls->key);
+      _Jv_Free (tls);
+    }
+}
+
+#else
+
+void
+java::lang::ThreadLocal::constructNative (void)
+{
+}
+
+void 
+java::lang::ThreadLocal::set (::java::lang::Object *value)
+{
+  internalSet (value);
+}
+
+::java::lang::Object *
+java::lang::ThreadLocal::get (void)
+{
+  return internalGet ();
+}
+
+void 
+java::lang::ThreadLocal::remove (void)
+{
+  internalRemove ();
+}
+
+void 
+java::lang::ThreadLocal::finalize (void)
+{
+}
+
+#endif
-- 
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