diff options
Diffstat (limited to 'src/backend/storage/ipc/ipci.c')
| -rw-r--r-- | src/backend/storage/ipc/ipci.c | 30 |
1 files changed, 17 insertions, 13 deletions
diff --git a/src/backend/storage/ipc/ipci.c b/src/backend/storage/ipc/ipci.c index 1a11508adf1..524a3598c25 100644 --- a/src/backend/storage/ipc/ipci.c +++ b/src/backend/storage/ipc/ipci.c @@ -8,7 +8,7 @@ * * * IDENTIFICATION - * $PostgreSQL: pgsql/src/backend/storage/ipc/ipci.c,v 1.72 2004/09/29 15:15:55 tgl Exp $ + * $PostgreSQL: pgsql/src/backend/storage/ipc/ipci.c,v 1.73 2004/12/29 21:36:06 tgl Exp $ * *------------------------------------------------------------------------- */ @@ -19,6 +19,7 @@ #include "access/xlog.h" #include "miscadmin.h" #include "postmaster/bgwriter.h" +#include "postmaster/postmaster.h" #include "storage/bufmgr.h" #include "storage/freespace.h" #include "storage/ipc.h" @@ -37,14 +38,15 @@ * Creates and initializes shared memory and semaphores. * * This is called by the postmaster or by a standalone backend. - * It is also called by a backend forked from the postmaster under - * the EXEC_BACKEND case. (In the non EXEC_BACKEND case, backends - * start life already attached to shared memory.) The initialization - * functions are set up to simply "attach" to pre-existing shared memory - * structures in the latter case. We have to do that in order to - * initialize pointers in local memory that reference the shared structures. - * (In the non EXEC_BACKEND case, these pointer values are inherited via - * fork() from the postmaster.) + * It is also called by a backend forked from the postmaster in the + * EXEC_BACKEND case. In the latter case, the shared memory segment + * already exists and has been physically attached to, but we have to + * initialize pointers in local memory that reference the shared structures, + * because we didn't inherit the correct pointer values from the postmaster + * as we do in the fork() scenario. The easiest way to do that is to run + * through the same code as before. (Note that the called routines mostly + * check IsUnderPostmaster, rather than EXEC_BACKEND, to detect this case. + * This is a bit code-wasteful and could be cleaned up.) * * If "makePrivate" is true then we only need private memory, not shared * memory. This is true for a standalone backend, false for a postmaster. @@ -101,14 +103,16 @@ CreateSharedMemoryAndSemaphores(bool makePrivate, else { /* - * Attach to the shmem segment. (this should only ever be reached - * by EXEC_BACKEND code, and only then with makePrivate == false) + * We are reattaching to an existing shared memory segment. + * This should only be reached in the EXEC_BACKEND case, and + * even then only with makePrivate == false. */ #ifdef EXEC_BACKEND Assert(!makePrivate); - seghdr = PGSharedMemoryCreate(-1, makePrivate, 0); + Assert(UsedShmemSegAddr != NULL); + seghdr = UsedShmemSegAddr; #else - Assert(false); + elog(PANIC, "should be attached to shared memory already"); #endif } |