Refactor code out of nscd's two main poll loops.

We refactor the inotify file checking code and the
database clearing code out of the main_loop_poll and
mail_loop_epoll functions. We document some the related
functions with appropriate comments.

diff --git a/ChangeLog b/ChangeLog
index ab411fdc9aedbc6d9305640723f59bb595e92268..7eb22652462f2383cb8894fc01f44186db0e1aa5 100644 (file)
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,13 @@
+2013-02-08  Carlos O'Donell  <carlos@redhat.com>
+
+       * nscd/connection.c (register_traced_file): Comment function.
+       [HAVE_INOTIFY] (union __inev): Define.
+       [HAVE_INOTIFY] (inotify_check_files): New function.
+       [HAVE_INOTIFY] (clear_db_cache): Likewise.
+       [HAVE_INOTIFY] (main_loop_poll): Call inotify_check_files and
+       clear_db_cache.
+       [HAVE_INOTIFY] (main_loop_epoll): Likewise.
+
 2013-02-08  Carlos O'Donell  <carlos@redhat.com>
 
        * elf/dl-cache.c (_dl_load_cache_lookup): Comment that cache is

diff --git a/nscd/connections.c b/nscd/connections.c
index feda2237f5be253dafb19a34593d9d40720f3928..56c327971b95e89b7f773bbdf05516c0ed190d80 100644 (file)
--- a/nscd/connections.c
+++ b/nscd/connections.c
@@ -976,9 +976,25 @@ cannot change socket to nonblocking mode: %s"),
 }
 
 
+/* Register the file in FINFO as a traced file for the database DBS[DBIX].
+
+   We support registering multiple files per database. Each call to
+   register_traced_file adds to the list of registered files.
+
+   When we prune the database, either through timeout or a request to
+   invalidate, we will check to see if any of the registered files has changed.
+   When we accept new connections to handle a cache request we will also
+   check to see if any of the registered files has changed.
+
+   If we have inotify support then we install an inotify fd to notify us of
+   file deletion or modification, both of which will require we invalidate
+   the cache for the database.  Without inotify support we stat the file and
+   store st_mtime to determine if the file has been modified.  */
 void
 register_traced_file (size_t dbidx, struct traced_file *finfo)
 {
+  /* If the database is disabled or file checking is disabled
+     then ignore the registration.  */
   if (! dbs[dbidx].enabled || ! dbs[dbidx].check_file)
     return;
 
@@ -1870,6 +1886,63 @@ restart_p (time_t now)
 /* Array for times a connection was accepted.  */
 static time_t *starttime;
 
+#ifdef HAVE_INOTIFY
+/* Inotify event for changed file.  */
+union __inev
+{
+  struct inotify_event i;
+# ifndef PATH_MAX
+#  define PATH_MAX 1024
+# endif
+  char buf[sizeof (struct inotify_event) + PATH_MAX];
+};
+
+/* Process the inotify event in INEV. If the event matches any of the files
+   registered with a database then mark that database as requiring its cache
+   to be cleared. We indicate the cache needs clearing by setting
+   TO_CLEAR[DBCNT] to true for the matching database.  */
+static inline void
+inotify_check_files (bool *to_clear, union __inev *inev)
+{
+  /* Check which of the files changed.  */
+  for (size_t dbcnt = 0; dbcnt < lastdb; ++dbcnt)
+    {
+      struct traced_file *finfo = dbs[dbcnt].traced_files;
+
+      while (finfo != NULL)
+       {
+         /* Inotify event watch descriptor matches.  */
+         if (finfo->inotify_descr == inev->i.wd)
+           {
+             /* Mark cache as needing to be cleared and reinitialize.  */
+             to_clear[dbcnt] = true;
+             if (finfo->call_res_init)
+               res_init ();
+             return;
+           }
+
+         finfo = finfo->next;
+        }
+    }
+}
+
+/* If an entry in the array of booleans TO_CLEAR is TRUE then clear the cache
+   for the associated database, otherwise do nothing. The TO_CLEAR array must
+   have LASTDB entries.  */
+static inline void
+clear_db_cache (bool *to_clear)
+{
+  for (size_t dbcnt = 0; dbcnt < lastdb; ++dbcnt)
+    if (to_clear[dbcnt])
+      {
+       pthread_mutex_lock (&dbs[dbcnt].prune_lock);
+       dbs[dbcnt].clear_cache = 1;
+       pthread_mutex_unlock (&dbs[dbcnt].prune_lock);
+       pthread_cond_signal (&dbs[dbcnt].prune_cond);
+      }
+}
+
+#endif
 
 static void
 __attribute__ ((__noreturn__))
@@ -1976,15 +2049,10 @@ main_loop_poll (void)
              if (conns[1].revents != 0)
                {
                  bool to_clear[lastdb] = { false, };
-                 union
-                 {
-# ifndef PATH_MAX
-#  define PATH_MAX 1024
-# endif
-                   struct inotify_event i;
-                   char buf[sizeof (struct inotify_event) + PATH_MAX];
-                 } inev;
+                 union __inev inev;
 
+                 /* Read all inotify events for files registered via
+                    register_traced_file().  */
                  while (1)
                    {
                      ssize_t nb = TEMP_FAILURE_RETRY (read (inotify_fd, &inev,
@@ -2010,35 +2078,11 @@ disabled inotify after read error %d"),
                        }
 
                      /* Check which of the files changed.  */
-                     for (size_t dbcnt = 0; dbcnt < lastdb; ++dbcnt)
-                       {
-                         struct traced_file *finfo = dbs[dbcnt].traced_files;
-
-                         while (finfo != NULL)
-                           {
-                             if (finfo->inotify_descr == inev.i.wd)
-                               {
-                                 to_clear[dbcnt] = true;
-                                 if (finfo->call_res_init)
-                                   res_init ();
-                                 goto next;
-                               }
-
-                             finfo = finfo->next;
-                           }
-                       }
-                   next:;
+                     inotify_check_files (to_clear, &inev);
                    }
 
                  /* Actually perform the cache clearing.  */
-                 for (size_t dbcnt = 0; dbcnt < lastdb; ++dbcnt)
-                   if (to_clear[dbcnt])
-                     {
-                       pthread_mutex_lock (&dbs[dbcnt].prune_lock);
-                       dbs[dbcnt].clear_cache = 1;
-                       pthread_mutex_unlock (&dbs[dbcnt].prune_lock);
-                       pthread_cond_signal (&dbs[dbcnt].prune_cond);
-                     }
+                 clear_db_cache (to_clear);
 
                  --n;
                }
@@ -2208,12 +2252,10 @@ main_loop_epoll (int efd)
        else if (revs[cnt].data.fd == inotify_fd)
          {
            bool to_clear[lastdb] = { false, };
-           union
-           {
-             struct inotify_event i;
-             char buf[sizeof (struct inotify_event) + PATH_MAX];
-           } inev;
+           union __inev inev;
 
+           /* Read all inotify events for files registered via
+              register_traced_file().  */
            while (1)
              {
                ssize_t nb = TEMP_FAILURE_RETRY (read (inotify_fd, &inev,
@@ -2235,35 +2277,11 @@ main_loop_epoll (int efd)
                  }
 
                /* Check which of the files changed.  */
-               for (size_t dbcnt = 0; dbcnt < lastdb; ++dbcnt)
-                 {
-                   struct traced_file *finfo = dbs[dbcnt].traced_files;
-
-                   while (finfo != NULL)
-                     {
-                       if (finfo->inotify_descr == inev.i.wd)
-                         {
-                           to_clear[dbcnt] = true;
-                           if (finfo->call_res_init)
-                             res_init ();
-                           goto next;
-                         }
-
-                       finfo = finfo->next;
-                     }
-                 }
-             next:;
+               inotify_check_files(to_clear, &inev);
              }
 
            /* Actually perform the cache clearing.  */
-           for (size_t dbcnt = 0; dbcnt < lastdb; ++dbcnt)
-             if (to_clear[dbcnt])
-               {
-                 pthread_mutex_lock (&dbs[dbcnt].prune_lock);
-                 dbs[dbcnt].clear_cache = 1;
-                 pthread_mutex_unlock (&dbs[dbcnt].prune_lock);
-                 pthread_cond_signal (&dbs[dbcnt].prune_cond);
-               }
+           clear_db_cache (to_clear);
          }
 # endif
 # ifdef HAVE_NETLINK