# HG changeset patch
# User Paul Boddie <paul@boddie.org.uk>
# Date 1631312170 -7200
# Node ID 494753f0112be086b3d4aed866a3f0accf65cc1b
# Parent  955a946c32f3594c377e5125c74fe39375ca1de9
Moved generic accounting functionality into a base class.

diff -r 955a946c32f3 -r 494753f0112b libfsserver/include/fsserver/accountable.h
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/libfsserver/include/fsserver/accountable.h	Sat Sep 11 00:16:10 2021 +0200
@@ -0,0 +1,44 @@
+/*
+ * Accountable object support.
+ *
+ * Copyright (C) 2021 Paul Boddie <paul@boddie.org.uk>
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License as
+ * published by the Free Software Foundation; either version 2 of
+ * the License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor,
+ * Boston, MA  02110-1301, USA
+ */
+
+#pragma once
+
+#include <mutex>
+
+
+
+/* An interface supporting usage accounting. */
+
+class Accountable
+{
+protected:
+    std::mutex _attached_lock;
+    unsigned int _attached = 0;
+
+public:
+    virtual ~Accountable();
+
+    virtual void attach();
+
+    virtual unsigned int detach();
+};
+
+// vim: tabstop=4 expandtab shiftwidth=4
diff -r 955a946c32f3 -r 494753f0112b libfsserver/include/fsserver/page_mapper.h
--- a/libfsserver/include/fsserver/page_mapper.h	Fri Sep 10 23:16:41 2021 +0200
+++ b/libfsserver/include/fsserver/page_mapper.h	Sat Sep 11 00:16:10 2021 +0200
@@ -23,6 +23,7 @@
 
 #include <fsserver/access_map.h>
 #include <fsserver/accessor.h>
+#include <fsserver/accountable.h>
 #include <fsserver/page_owner.h>
 
 #include <mutex>
@@ -31,13 +32,12 @@
 
 /* A file mapper, associating flexpages with file regions. */
 
-class PageMapper : public PageOwner
+class PageMapper : public PageOwner, public Accountable
 {
 protected:
     AccessMap _map;
     Accessor *_accessor;
     Pages *_pages;
-    unsigned int _attached;
 
     /* Serialisation of accesses. */
 
@@ -52,9 +52,7 @@
 public:
     explicit PageMapper(Accessor *accessor, Pages *pages);
 
-    /* Accounting methods. */
-
-    void attach();
+    /* Specialised accounting methods. */
 
     unsigned int detach();
 
diff -r 955a946c32f3 -r 494753f0112b libfsserver/lib/Makefile
--- a/libfsserver/lib/Makefile	Fri Sep 10 23:16:41 2021 +0200
+++ b/libfsserver/lib/Makefile	Sat Sep 11 00:16:10 2021 +0200
@@ -60,6 +60,7 @@
 					files/test_file_accessor.cc \
 					files/test_file_opener.cc \
 					generic/accessor.cc \
+					generic/accountable.cc \
 					generic/notification.cc \
 					generic/pager.cc \
 					generic/resource_server.cc \
diff -r 955a946c32f3 -r 494753f0112b libfsserver/lib/generic/accountable.cc
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/libfsserver/lib/generic/accountable.cc	Sat Sep 11 00:16:10 2021 +0200
@@ -0,0 +1,51 @@
+/*
+ * Accountable object support.
+ *
+ * Copyright (C) 2021 Paul Boddie <paul@boddie.org.uk>
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License as
+ * published by the Free Software Foundation; either version 2 of
+ * the License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor,
+ * Boston, MA  02110-1301, USA
+ */
+
+#include "accountable.h"
+
+
+
+Accountable::~Accountable()
+{
+}
+
+/* Attach to the object. */
+
+void Accountable::attach()
+{
+    std::lock_guard<std::mutex> guard(_attached_lock);
+
+    _attached += 1;
+}
+
+/* Detach from the object. */
+
+unsigned int Accountable::detach()
+{
+    std::lock_guard<std::mutex> guard(_attached_lock);
+
+    if (_attached)
+        _attached -= 1;
+
+    return _attached;
+}
+
+// vim: tabstop=4 expandtab shiftwidth=4
diff -r 955a946c32f3 -r 494753f0112b libfsserver/lib/mapping/page_mapper.cc
--- a/libfsserver/lib/mapping/page_mapper.cc	Fri Sep 10 23:16:41 2021 +0200
+++ b/libfsserver/lib/mapping/page_mapper.cc	Sat Sep 11 00:16:10 2021 +0200
@@ -25,40 +25,26 @@
 
 
 PageMapper::PageMapper(Accessor *accessor, Pages *pages)
-: _accessor(accessor), _pages(pages), _attached(0)
+: _accessor(accessor), _pages(pages)
 {
 }
 
 /* Accounting methods. */
 
-/* Attach a pager, opening the accessor if required. */
-
-void PageMapper::attach()
-{
-    std::lock_guard<std::mutex> guard(_lock);
-
-    _attached += 1;
-}
-
 /* Detach a pager, purging active pages and closing the accessor if no more
    pagers are attached. Return whether any pagers are still attached. */
 
 unsigned int PageMapper::detach()
 {
-    std::lock_guard<std::mutex> guard(_lock);
-
-    if (_attached)
-    {
-        _attached -= 1;
+    unsigned int attached = Accountable::detach();
 
-        if (!_attached)
-        {
-            _map.purge(this, _pages);
-            _accessor->close();
-        }
+    if (!attached)
+    {
+        _map.purge(this, _pages);
+        _accessor->close();
     }
 
-    return _attached;
+    return attached;
 }
 
 /* Interface for the pager. */