Add overloads of for_each_thread/find_thread that filter on pid

It happens often that we want to iterate or find threads restricted to a
given pid.  I think it's worth having an overload to help with this.
Right now there is a single user of each of the find_thread and
for_each_thread overload, but as we replace the usages of find_inferior
with for_each_thread/find_thread, more usages will pop up.

gdb/gdbserver/ChangeLog:

	* gdbthread.h (find_thread, for_each_thread): New functions.
	* inferiors.c (thread_of_pid): Remove.
	(find_any_thread_of_pid): Use find_thread.
	* linux-low.c (num_lwps): Use for_each_thread.

1 files changed, 25 insertions, 0 deletions

diff --git a/gdb/gdbserver/gdbthread.h b/gdb/gdbserver/gdbthread.h
index 8ace051..b82d5b0 100644
--- a/gdb/gdbserver/gdbthread.h
+++ b/gdb/gdbserver/gdbthread.h
@@ -111,6 +111,18 @@ find_thread (Func func)
   return NULL;
 }
 
+/* Like the above, but only consider threads with pid PID.  */
+
+template <typename Func>
+static thread_info *
+find_thread (int pid, Func func)
+{
+  return find_thread ([&] (thread_info *thread)
+    {
+      return thread->id.pid () == pid && func (thread);
+    });
+}
+
 /* Invoke FUNC for each thread.  */
 
 template <typename Func>
@@ -128,6 +140,19 @@ for_each_thread (Func func)
     }
 }
 
+/* Like the above, but only consider threads with pid PID.  */
+
+template <typename Func>
+static void
+for_each_thread (int pid, Func func)
+{
+  for_each_thread ([&] (thread_info *thread)
+    {
+      if (pid == thread->id.pid ())
+	func (thread);
+    });
+}
+
 /* Find the a random thread for which FUNC (THREAD) returns true.  If
    no entry is found then return NULL.  */