Avoid a memory allocation in the backend startup code, to avoid having to check

whether it failed.  Modelled after catcache.c's usage of DlList, per suggestion
from Tom.

diff --git a/src/backend/postmaster/postmaster.c b/src/backend/postmaster/postmaster.c
index 9f7aef1a93f5c06db4fb4f6b9cb7492534cede50..7cf6293bdce8b66f17dd0388d0044e15228081c8 100644 (file)
--- a/src/backend/postmaster/postmaster.c
+++ b/src/backend/postmaster/postmaster.c
@@ -37,7 +37,7 @@
  *
  *
  * IDENTIFICATION
- *   $PostgreSQL: pgsql/src/backend/postmaster/postmaster.c,v 1.578 2009/05/02 22:02:37 tgl Exp $
+ *   $PostgreSQL: pgsql/src/backend/postmaster/postmaster.c,v 1.579 2009/05/04 02:24:17 alvherre Exp $
  *
  * NOTES
  *
@@ -143,6 +143,7 @@ typedef struct bkend
    long        cancel_key;     /* cancel key for cancels for this backend */
    bool        is_autovacuum;  /* is it an autovacuum process? */
    bool        dead_end;       /* is it going to send an error and quit? */
+   Dlelem      elem;           /* self pointer into BackendList */
 } Backend;
 
 static Dllist *BackendList;
@@ -2459,7 +2460,6 @@ CleanupBackend(int pid,
 #endif
            DLRemove(curr);
            free(bp);
-           DLFreeElem(curr);
            break;
        }
    }
@@ -2506,7 +2506,6 @@ HandleChildCrash(int pid, int exitstatus, const char *procname)
 #endif
            DLRemove(curr);
            free(bp);
-           DLFreeElem(curr);
            /* Keep looping so we can signal remaining backends */
        }
        else
@@ -3014,7 +3013,8 @@ BackendStartup(Port *port)
    bn->is_autovacuum = false;
    bn->dead_end = (port->canAcceptConnections != CAC_OK &&
                    port->canAcceptConnections != CAC_WAITBACKUP);
-   DLAddHead(BackendList, DLNewElem(bn));
+   DLInitElem(&bn->elem, bn);
+   DLAddHead(BackendList, &bn->elem);
 #ifdef EXEC_BACKEND
    if (!bn->dead_end)
        ShmemBackendArrayAdd(bn);