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Make it easy to detach completely from shared memory.

The new function dsm_detach_all() can be used either by postmasterchildren that don't wish to take any risk of accidentally corruptingshared memory; or by forked children of regular backends withthe same need. This patch also updates the postmaster children thatalready do PGSharedMemoryDetach() to do dsm_detach_all() as well.Per discussion with Tom Lane.

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5 files changed

+34

-0

lines changed

src
- backend
  - postmaster
  - storage/ipc
    - dsm.c
- include/storage
  - dsm.h

5 files changed

+34

-0

lines changed

`‎src/backend/postmaster/pgarch.c‎`

Lines changed: 2 additions & 0 deletions

Original file line number	Diff line number	Diff line change
`@@ -40,6 +40,7 @@`
`40`	`40`	`#include"postmaster/fork_process.h"`
`41`	`41`	`#include"postmaster/pgarch.h"`
`42`	`42`	`#include"postmaster/postmaster.h"`
	`43`	`+#include"storage/dsm.h"`
`43`	`44`	`#include"storage/fd.h"`
`44`	`45`	`#include"storage/ipc.h"`
`45`	`46`	`#include"storage/latch.h"`
`@@ -163,6 +164,7 @@ pgarch_start(void)`
`163`	`164`	`on_exit_reset();`
`164`	`165`
`165`	`166`	`/* Drop our connection to postmaster's shared memory, as well */`
	`167`	`+dsm_detach_all();`
`166`	`168`	`PGSharedMemoryDetach();`
`167`	`169`
`168`	`170`	`PgArchiverMain(0,NULL);`

`‎src/backend/postmaster/pgstat.c‎`

Lines changed: 2 additions & 0 deletions

Original file line number	Diff line number	Diff line change
`@@ -50,6 +50,7 @@`
`50`	`50`	`#include"postmaster/postmaster.h"`
`51`	`51`	`#include"storage/proc.h"`
`52`	`52`	`#include"storage/backendid.h"`
	`53`	`+#include"storage/dsm.h"`
`53`	`54`	`#include"storage/fd.h"`
`54`	`55`	`#include"storage/ipc.h"`
`55`	`56`	`#include"storage/latch.h"`
`@@ -709,6 +710,7 @@ pgstat_start(void)`
`709`	`710`	`on_exit_reset();`
`710`	`711`
`711`	`712`	`/* Drop our connection to postmaster's shared memory, as well */`
	`713`	`+dsm_detach_all();`
`712`	`714`	`PGSharedMemoryDetach();`
`713`	`715`
`714`	`716`	`PgstatCollectorMain(0,NULL);`

`‎src/backend/postmaster/syslogger.c‎`

Lines changed: 2 additions & 0 deletions

Original file line number	Diff line number	Diff line change
`@@ -39,6 +39,7 @@`
`39`	`39`	`#include"postmaster/fork_process.h"`
`40`	`40`	`#include"postmaster/postmaster.h"`
`41`	`41`	`#include"postmaster/syslogger.h"`
	`42`	`+#include"storage/dsm.h"`
`42`	`43`	`#include"storage/ipc.h"`
`43`	`44`	`#include"storage/latch.h"`
`44`	`45`	`#include"storage/pg_shmem.h"`
`@@ -626,6 +627,7 @@ SysLogger_Start(void)`
`626`	`627`	`on_exit_reset();`
`627`	`628`
`628`	`629`	`/* Drop our connection to postmaster's shared memory, as well */`
	`630`	`+dsm_detach_all();`
`629`	`631`	`PGSharedMemoryDetach();`
`630`	`632`
`631`	`633`	`/* do the work */`

`‎src/backend/storage/ipc/dsm.c‎`

Lines changed: 27 additions & 0 deletions

Original file line number	Diff line number	Diff line change
`@@ -722,6 +722,8 @@ dsm_attach(dsm_handle h)`
`722`	`722`
`723`	`723`	`/*`
`724`	`724`	`* At backend shutdown time, detach any segments that are still attached.`
	`725`	`+ * (This is similar to dsm_detach_all, except that there's no reason to`
	`726`	`+ * unmap the control segment before exiting, so we don't bother.)`
`725`	`727`	`*/`
`726`	`728`	`void`
`727`	`729`	`dsm_backend_shutdown(void)`
`@@ -735,6 +737,31 @@ dsm_backend_shutdown(void)`
`735`	`737`	`}`
`736`	`738`	`}`
`737`	`739`
	`740`	`+/*`
	`741`	`+ * Detach all shared memory segments, including the control segments. This`
	`742`	`+ * should be called, along with PGSharedMemoryDetach, in processes that`
	`743`	`+ * might inherit mappings but are not intended to be connected to dynamic`
	`744`	`+ * shared memory.`
	`745`	`+ */`
	`746`	`+void`
	`747`	`+dsm_detach_all(void)`
	`748`	`+{`
	`749`	`+void*control_address=dsm_control;`
	`750`	`+`
	`751`	`+while (!dlist_is_empty(&dsm_segment_list))`
	`752`	`+{`
	`753`	`+dsm_segment*seg;`
	`754`	`+`
	`755`	`+seg=dlist_head_element(dsm_segment,node,&dsm_segment_list);`
	`756`	`+dsm_detach(seg);`
	`757`	`+}`
	`758`	`+`
	`759`	`+if (control_address!=NULL)`
	`760`	`+dsm_impl_op(DSM_OP_DETACH,dsm_control_handle,0,`
	`761`	`+&dsm_control_impl_private,&control_address,`
	`762`	`+&dsm_control_mapped_size,ERROR);`
	`763`	`+}`
	`764`	`+`
`738`	`765`	`/*`
`739`	`766`	`* Resize an existing shared memory segment.`
`740`	`767`	`*`

`‎src/include/storage/dsm.h‎`

Lines changed: 1 addition & 0 deletions

Original file line number	Diff line number	Diff line change
`@@ -20,6 +20,7 @@ typedef struct dsm_segment dsm_segment;`
`20`	`20`	`/* Startup and shutdown functions. */`
`21`	`21`	`externvoiddsm_postmaster_startup(void);`
`22`	`22`	`externvoiddsm_backend_shutdown(void);`
	`23`	`+externvoiddsm_detach_all(void);`
`23`	`24`
`24`	`25`	`/* Functions that create, update, or remove mappings. */`
`25`	`26`	`externdsm_segment*dsm_create(Sizesize);`

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Commit79a4d24

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5 files changed

5 files changed

`‎src/backend/postmaster/pgarch.c‎`

`‎src/backend/postmaster/pgstat.c‎`

`‎src/backend/postmaster/syslogger.c‎`

`‎src/backend/storage/ipc/dsm.c‎`

`‎src/include/storage/dsm.h‎`

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