Add server support for "plugin" libraries that can be used for add-on tasks

such as debugging and performance measurement.  This consists of two features:
a table of "rendezvous variables" that allows separately-loaded shared
libraries to communicate, and a new GUC setting "local_preload_libraries"
that allows libraries to be loaded into specific sessions without explicit
cooperation from the client application.  To make local_preload_libraries
as flexible as possible, we do not restrict its use to superusers; instead,
it is restricted to load only libraries stored in $libdir/plugins/.  The
existing LOAD command has also been modified to allow non-superusers to
LOAD libraries stored in this directory.

This patch also renames the existing GUC variable preload_libraries to
shared_preload_libraries (after a suggestion by Simon Riggs) and does some
code refactoring in dfmgr.c to improve clarity.

Korry Douglas, with a little help from Tom Lane.

2 files changed, 8 insertions, 5 deletions

diff --git a/src/include/fmgr.h b/src/include/fmgr.h
index 5b904cbad4..2e9e3f7182 100644
--- a/src/include/fmgr.h
+++ b/src/include/fmgr.h
@@ -11,7 +11,7 @@
  * Portions Copyright (c) 1996-2006, PostgreSQL Global Development Group
  * Portions Copyright (c) 1994, Regents of the University of California
  *
- * $PostgreSQL: pgsql/src/include/fmgr.h,v 1.45 2006/05/31 20:58:09 tgl Exp $
+ * $PostgreSQL: pgsql/src/include/fmgr.h,v 1.46 2006/08/15 18:26:59 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -488,7 +488,8 @@ extern char *Dynamic_library_path;
 extern PGFunction load_external_function(char *filename, char *funcname,
 					   bool signalNotFound, void **filehandle);
 extern PGFunction lookup_external_function(void *filehandle, char *funcname);
-extern void load_file(char *filename);
+extern void load_file(const char *filename, bool restrict);
+extern void **find_rendezvous_variable(const char *varName);
 
 
 /*
diff --git a/src/include/miscadmin.h b/src/include/miscadmin.h
index 07590c9294..8a050f5b7d 100644
--- a/src/include/miscadmin.h
+++ b/src/include/miscadmin.h
@@ -13,7 +13,7 @@
  * Portions Copyright (c) 1996-2006, PostgreSQL Global Development Group
  * Portions Copyright (c) 1994, Regents of the University of California
  *
- * $PostgreSQL: pgsql/src/include/miscadmin.h,v 1.187 2006/08/08 19:15:08 tgl Exp $
+ * $PostgreSQL: pgsql/src/include/miscadmin.h,v 1.188 2006/08/15 18:26:59 tgl Exp $
  *
  * NOTES
  *	  some of the information in this file should be moved to other files.
@@ -307,7 +307,8 @@ extern void BaseInit(void);
 
 /* in utils/init/miscinit.c */
 extern bool IgnoreSystemIndexes;
-extern char *preload_libraries_string;
+extern char *shared_preload_libraries_string;
+extern char *local_preload_libraries_string;
 
 extern void SetReindexProcessing(Oid heapOid, Oid indexOid);
 extern void ResetReindexProcessing(void);
@@ -319,6 +320,7 @@ extern void TouchSocketLockFile(void);
 extern void RecordSharedMemoryInLockFile(unsigned long id1,
 							 unsigned long id2);
 extern void ValidatePgVersion(const char *path);
-extern void process_preload_libraries(void);
+extern void process_shared_preload_libraries(void);
+extern void process_local_preload_libraries(void);
 
 #endif   /* MISCADMIN_H */