Remove the dlopen() pointer from struct filedef.

This pointer is almost never needed, and it increases the size of the filedef
struct for all files (of which there are a huge number for large builds).
Instead keep a bit field marking whether the file is a loaded object and if so
call a new function to unload it.  In load.c we keep a simple linked list of
loaded objects (of which there will be very few typically) and their dlopen()
pointers.

7 files changed, 79 insertions, 25 deletions

diff --git a/ChangeLog b/ChangeLog
index c317594..d9c3167 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,21 @@
+2013-05-17  Paul Smith  <psmith@gnu.org>
+
+	* makeint.h: Prototype new unload_file() function.
+	* load.c (unload_file): Create a function to unload a file.
+	(struct load_list): Type to remember loaded objects.
+	(loaded_syms): Global variable of remembered loaded objects so we
+	can unload them later.  We don't have to remove from the list
+	because the only time we unload is if we're about to re-exec.
+	(load_object): Remove unneeded extra DLP argument.
+	(load_file): Remove unneeded extra DLP argument.
+	* filedef.h (struct file): Remove the DLP pointer and add the
+	LOADED bit flag.  Saves 32/64 bytes per file, as this pointer is
+	almost never needed.
+	* read.c (eval): Set the new LOADED bit flag on the file.
+	* file.c (rehash_file): Merge the loaded bitfield.
+	* commands.c (execute_file_commands): Call unload_file() instead
+	of dlclose() directly.
+
 2013-05-14  Paul Smith  <psmith@gnu.org>
 
 	* doc/make.texi (Loaded Object API): Document the requirement for
diff --git a/commands.c b/commands.c
index e8a9f1c..1627702 100644
--- a/commands.c
+++ b/commands.c
@@ -471,10 +471,9 @@ execute_file_commands (struct file *file)
   set_file_variables (file);
 
   /* If this is a loaded dynamic object, unload it before remaking.
-     Some systems don't allow to overwrite a loaded shared
-     library.  */
-  if (file->dlopen_ptr)
-    dlclose (file->dlopen_ptr);
+     Some systems don't support overwriting a loaded object.  */
+  if (file->loaded)
+    unload_file (file->name);
 
   /* Start the commands running.  */
   new_job (file);
diff --git a/file.c b/file.c
index 444a81d..b77efad 100644
--- a/file.c
+++ b/file.c
@@ -322,6 +322,7 @@ rehash_file (struct file *from_file, const char *to_hname)
   MERGE (is_target);
   MERGE (cmd_target);
   MERGE (phony);
+  MERGE (loaded);
   MERGE (ignore_vpath);
 #undef MERGE
 
diff --git a/filedef.h b/filedef.h
index 5fa6429..001b904 100644
--- a/filedef.h
+++ b/filedef.h
@@ -61,8 +61,6 @@ struct file
     int command_flags;		/* Flags OR'd in for cmds; see commands.h.  */
     char update_status;         /* Status of the last attempt to update,
 				   or -1 if none has been made.  */
-    void *dlopen_ptr;		/* For dynamic loaded objects: pointer to
-				   pass to dlclose to unload the object.  */
     enum cmd_state		/* State of the commands.  */
       {		/* Note: It is important that cs_not_started be zero.  */
 	cs_not_started,		/* Not yet started.  */
@@ -71,7 +69,9 @@ struct file
 	cs_finished		/* Commands finished.  */
       } command_state ENUM_BITFIELD (2);
 
+    unsigned int builtin:1;     /* True if the file is a builtin rule. */
     unsigned int precious:1;	/* Non-0 means don't delete file on quit */
+    unsigned int loaded:1;      /* True if the file is a loaded object. */
     unsigned int low_resolution_time:1;	/* Nonzero if this file's time stamp
 					   has only one-second resolution.  */
     unsigned int tried_implicit:1; /* Nonzero if have searched
@@ -95,7 +95,6 @@ struct file
                                    considered on current scan of goal chain */
     unsigned int no_diag:1;     /* True if the file failed to update and no
                                    diagnostics has been issued (dontcare). */
-    unsigned int builtin:1;     /* True if the file is a builtin rule. */
   };
 
 
diff --git a/load.c b/load.c
index 655928a..6147741 100644
--- a/load.c
+++ b/load.c
@@ -30,15 +30,22 @@ this program.  If not, see <http://www.gnu.org/licenses/>.  */
 #include "filedef.h"
 #include "variable.h"
 
+struct load_list
+  {
+    struct load_list *next;
+    const char *name;
+    void *dlp;
+  };
+
+static struct load_list *loaded_syms = NULL;
+
 static load_func_t
 load_object (const gmk_floc *flocp, int noerror,
-             const char *ldname, const char *symname, void **dlp)
+             const char *ldname, const char *symname)
 {
   static void *global_dl = NULL;
   load_func_t symp;
 
-  *dlp = NULL;
-
   if (! global_dl)
     {
       global_dl = dlopen (NULL, RTLD_NOW|RTLD_GLOBAL);
@@ -48,6 +55,8 @@ load_object (const gmk_floc *flocp, int noerror,
 
   symp = (load_func_t) dlsym (global_dl, symname);
   if (! symp) {
+    struct load_list *new;
+    void *dlp = NULL;
 
     /* If the path has no "/", try the current directory first.  */
     if (! strchr (ldname, '/')
@@ -55,14 +64,14 @@ load_object (const gmk_floc *flocp, int noerror,
 	&& ! strchr (ldname, '\\')
 #endif
 	)
-      *dlp = dlopen (concat (2, "./", ldname), RTLD_LAZY|RTLD_GLOBAL);
+      dlp = dlopen (concat (2, "./", ldname), RTLD_LAZY|RTLD_GLOBAL);
 
     /* If we haven't opened it yet, try the default search path.  */
-    if (! *dlp)
-      *dlp = dlopen (ldname, RTLD_LAZY|RTLD_GLOBAL);
+    if (! dlp)
+      dlp = dlopen (ldname, RTLD_LAZY|RTLD_GLOBAL);
 
     /* Still no?  Then fail.  */
-    if (! *dlp)
+    if (! dlp)
       {
         if (noerror)
           DB (DB_BASIC, ("%s", dlerror()));
@@ -72,22 +81,31 @@ load_object (const gmk_floc *flocp, int noerror,
       }
 
     /* Assert that the GPL license symbol is defined.  */
-    symp = dlsym (*dlp, "plugin_is_GPL_compatible");
+    symp = dlsym (dlp, "plugin_is_GPL_compatible");
     if (! symp)
       fatal (flocp, _("Loaded object %s is not declared to be GPL compatible"),
              ldname);
 
-    symp = dlsym (*dlp, symname);
+    symp = dlsym (dlp, symname);
     if (! symp)
       fatal (flocp, _("Failed to load symbol %s from %s: %s"),
              symname, ldname, dlerror());
+
+    /* Add this symbol to a trivial lookup table.  This is not efficient but
+       it's highly unlikely we'll be loading lots of objects, and we only need
+       it to look them up on unload, if we rebuild them.  */
+    new = xmalloc (sizeof (struct load_list));
+    new->name = xstrdup (ldname);
+    new->dlp = dlp;
+    new->next = loaded_syms;
+    loaded_syms = new;
   }
 
   return symp;
 }
 
 int
-load_file (const gmk_floc *flocp, const char **ldname, int noerror, void **dlp)
+load_file (const gmk_floc *flocp, const char **ldname, int noerror)
 {
   int nmlen = strlen (*ldname);
   char *new = alloca (nmlen + CSTRLEN (SYMBOL_EXTENSION) + 1);
@@ -97,8 +115,6 @@ load_file (const gmk_floc *flocp, const char **ldname, int noerror, void **dlp)
   int r;
   load_func_t symp;
 
-  *dlp = NULL;
-
   /* Break the input into an object file name and a symbol name.  If no symbol
      name was provided, compute one from the object file name.  */
   fp = strchr (*ldname, '(');
@@ -174,7 +190,7 @@ load_file (const gmk_floc *flocp, const char **ldname, int noerror, void **dlp)
   DB (DB_VERBOSE, (_("Loading symbol %s from %s\n"), symname, *ldname));
 
   /* Load it!  */
-  symp = load_object(flocp, noerror, *ldname, symname, dlp);
+  symp = load_object(flocp, noerror, *ldname, symname);
   if (! symp)
     return 0;
 
@@ -188,6 +204,21 @@ load_file (const gmk_floc *flocp, const char **ldname, int noerror, void **dlp)
   return r;
 }
 
+void
+unload_file (const char *name)
+{
+  struct load_list *d;
+
+  for (d = loaded_syms; d != NULL; d = d->next)
+    if (streq (d->name, name) && d->dlp)
+      {
+        if (dlclose (d->dlp))
+          perror_with_name ("dlclose", d->name);
+        d->dlp = NULL;
+        break;
+      }
+}
+
 #else
 
 int
@@ -199,4 +230,11 @@ load_file (const gmk_floc *flocp, const char **ldname, int noerror)
   return 0;
 }
 
+int
+unload_file (struct file *file)
+{
+  fatal (flocp, "INTERNAL: Cannot unload when load is not supported!");
+  return 0;
+}
+
 #endif  /* MAKE_LOAD */
diff --git a/makeint.h b/makeint.h
index 9d351c9..72124ec 100644
--- a/makeint.h
+++ b/makeint.h
@@ -490,8 +490,8 @@ int guile_gmake_setup (const gmk_floc *flocp);
 
 /* Loadable object support.  Sets to the strcached name of the loaded file.  */
 typedef int (*load_func_t)(const gmk_floc *flocp);
-int load_file (const gmk_floc *flocp, const char **filename, int noerror,
-	       void **dlp);
+int load_file (const gmk_floc *flocp, const char **filename, int noerror);
+void unload_file (const char *name);
 
 /* We omit these declarations on non-POSIX systems which define _POSIX_VERSION,
    because such systems often declare them in header files anyway.  */
diff --git a/read.c b/read.c
index 50f8414..9dce583 100644
--- a/read.c
+++ b/read.c
@@ -937,12 +937,11 @@ eval (struct ebuffer *ebuf, int set_default)
               struct nameseq *next = files->next;
               const char *name = files->name;
               struct dep *deps;
-              void *dlp;
 
               free_ns (files);
               files = next;
 
-              if (! load_file (&ebuf->floc, &name, noerror, &dlp) && ! noerror)
+              if (! load_file (&ebuf->floc, &name, noerror) && ! noerror)
                 fatal (&ebuf->floc, _("%s: failed to load"), name);
 
               deps = alloc_dep ();
@@ -951,7 +950,7 @@ eval (struct ebuffer *ebuf, int set_default)
               deps->file = lookup_file (name);
               if (deps->file == 0)
                 deps->file = enter_file (name);
-              deps->file->dlopen_ptr = dlp;
+              deps->file->loaded = 1;
             }
 
           continue;