aboutsummaryrefslogtreecommitdiff
path: root/src
diff options
context:
space:
mode:
Diffstat (limited to 'src')
-rw-r--r--src/backend/port/sysv_shmem.c12
-rw-r--r--src/backend/port/win32_shmem.c6
-rw-r--r--src/backend/storage/ipc/dsm.c200
-rw-r--r--src/backend/storage/ipc/ipci.c6
-rw-r--r--src/include/storage/dsm.h8
-rw-r--r--src/include/storage/pg_shmem.h5
6 files changed, 71 insertions, 166 deletions
diff --git a/src/backend/port/sysv_shmem.c b/src/backend/port/sysv_shmem.c
index 51c1a2b71f8..5e3850b024d 100644
--- a/src/backend/port/sysv_shmem.c
+++ b/src/backend/port/sysv_shmem.c
@@ -30,6 +30,7 @@
#include "miscadmin.h"
#include "portability/mem.h"
+#include "storage/dsm.h"
#include "storage/ipc.h"
#include "storage/pg_shmem.h"
#include "utils/guc.h"
@@ -421,7 +422,8 @@ CreateAnonymousSegment(Size *size)
* zero will be passed.
*/
PGShmemHeader *
-PGSharedMemoryCreate(Size size, bool makePrivate, int port)
+PGSharedMemoryCreate(Size size, bool makePrivate, int port,
+ PGShmemHeader **shim)
{
IpcMemoryKey NextShmemSegID;
void *memAddress;
@@ -509,10 +511,13 @@ PGSharedMemoryCreate(Size size, bool makePrivate, int port)
/*
* The segment appears to be from a dead Postgres process, or from a
- * previous cycle of life in this same process. Zap it, if possible.
+ * previous cycle of life in this same process. Zap it, if possible,
+ * and any associated dynamic shared memory segments, as well.
* This probably shouldn't fail, but if it does, assume the segment
* belongs to someone else after all, and continue quietly.
*/
+ if (hdr->dsm_control != 0)
+ dsm_cleanup_using_control_segment(hdr->dsm_control);
shmdt(memAddress);
if (shmctl(shmid, IPC_RMID, NULL) < 0)
continue;
@@ -539,6 +544,7 @@ PGSharedMemoryCreate(Size size, bool makePrivate, int port)
hdr = (PGShmemHeader *) memAddress;
hdr->creatorPID = getpid();
hdr->magic = PGShmemMagic;
+ hdr->dsm_control = 0;
/* Fill in the data directory ID info, too */
if (stat(DataDir, &statbuf) < 0)
@@ -554,6 +560,7 @@ PGSharedMemoryCreate(Size size, bool makePrivate, int port)
*/
hdr->totalsize = size;
hdr->freeoffset = MAXALIGN(sizeof(PGShmemHeader));
+ *shim = hdr;
/* Save info for possible future use */
UsedShmemSegAddr = memAddress;
@@ -608,6 +615,7 @@ PGSharedMemoryReAttach(void)
if (hdr != origUsedShmemSegAddr)
elog(FATAL, "reattaching to shared memory returned unexpected address (got %p, expected %p)",
hdr, origUsedShmemSegAddr);
+ dsm_set_control_handle(((PGShmemHeader *) hdr)->dsm_control);
UsedShmemSegAddr = hdr; /* probably redundant */
}
diff --git a/src/backend/port/win32_shmem.c b/src/backend/port/win32_shmem.c
index dca371cce62..3a0ded48650 100644
--- a/src/backend/port/win32_shmem.c
+++ b/src/backend/port/win32_shmem.c
@@ -117,7 +117,8 @@ PGSharedMemoryIsInUse(unsigned long id1, unsigned long id2)
*
*/
PGShmemHeader *
-PGSharedMemoryCreate(Size size, bool makePrivate, int port)
+PGSharedMemoryCreate(Size size, bool makePrivate, int port,
+ PGShmemHeader **shim)
{
void *memAddress;
PGShmemHeader *hdr;
@@ -245,12 +246,14 @@ PGSharedMemoryCreate(Size size, bool makePrivate, int port)
*/
hdr->totalsize = size;
hdr->freeoffset = MAXALIGN(sizeof(PGShmemHeader));
+ hdr->dsm_control = 0;
/* Save info for possible future use */
UsedShmemSegAddr = memAddress;
UsedShmemSegSize = size;
UsedShmemSegID = hmap2;
+ *shim = NULL;
return hdr;
}
@@ -289,6 +292,7 @@ PGSharedMemoryReAttach(void)
hdr, origUsedShmemSegAddr);
if (hdr->magic != PGShmemMagic)
elog(FATAL, "reattaching to shared memory returned non-PostgreSQL memory");
+ dsm_set_control_handle(hdr->dsm_control);
UsedShmemSegAddr = hdr; /* probably redundant */
}
diff --git a/src/backend/storage/ipc/dsm.c b/src/backend/storage/ipc/dsm.c
index c967177c4b1..6c410f77d9e 100644
--- a/src/backend/storage/ipc/dsm.c
+++ b/src/backend/storage/ipc/dsm.c
@@ -39,13 +39,11 @@
#include "storage/dsm.h"
#include "storage/ipc.h"
#include "storage/lwlock.h"
+#include "storage/pg_shmem.h"
#include "utils/guc.h"
#include "utils/memutils.h"
#include "utils/resowner_private.h"
-#define PG_DYNSHMEM_STATE_FILE PG_DYNSHMEM_DIR "/state"
-#define PG_DYNSHMEM_NEW_STATE_FILE PG_DYNSHMEM_DIR "/state.new"
-#define PG_DYNSHMEM_STATE_BUFSIZ 512
#define PG_DYNSHMEM_CONTROL_MAGIC 0x9a503d32
/*
@@ -95,10 +93,7 @@ typedef struct dsm_control_header
dsm_control_item item[FLEXIBLE_ARRAY_MEMBER];
} dsm_control_header;
-static void dsm_cleanup_using_control_segment(void);
static void dsm_cleanup_for_mmap(void);
-static bool dsm_read_state_file(dsm_handle *h);
-static void dsm_write_state_file(dsm_handle h);
static void dsm_postmaster_shutdown(int code, Datum arg);
static dsm_segment *dsm_create_descriptor(void);
static bool dsm_control_segment_sane(dsm_control_header *control,
@@ -146,7 +141,7 @@ static void *dsm_control_impl_private = NULL;
* startup time.
*/
void
-dsm_postmaster_startup(void)
+dsm_postmaster_startup(PGShmemHeader *shim)
{
void *dsm_control_address = NULL;
uint32 maxitems;
@@ -159,26 +154,13 @@ dsm_postmaster_startup(void)
return;
/*
- * Check for, and remove, shared memory segments left behind by a dead
- * postmaster. This isn't necessary on Windows, which always removes them
- * when the last reference is gone.
+ * If we're using the mmap implementations, clean up any leftovers.
+ * Cleanup isn't needed on Windows, and happens earlier in startup for
+ * POSIX and System V shared memory, via a direct call to
+ * dsm_cleanup_using_control_segment.
*/
- switch (dynamic_shared_memory_type)
- {
- case DSM_IMPL_POSIX:
- case DSM_IMPL_SYSV:
- dsm_cleanup_using_control_segment();
- break;
- case DSM_IMPL_MMAP:
- dsm_cleanup_for_mmap();
- break;
- case DSM_IMPL_WINDOWS:
- /* Nothing to do. */
- break;
- default:
- elog(ERROR, "unknown dynamic shared memory type: %d",
- dynamic_shared_memory_type);
- }
+ if (dynamic_shared_memory_type == DSM_IMPL_MMAP)
+ dsm_cleanup_for_mmap();
/* Determine size for new control segment. */
maxitems = PG_DYNSHMEM_FIXED_SLOTS
@@ -187,23 +169,30 @@ dsm_postmaster_startup(void)
maxitems);
segsize = dsm_control_bytes_needed(maxitems);
- /* Loop until we find an unused identifier for the new control segment. */
+ /*
+ * Loop until we find an unused identifier for the new control segment.
+ * We sometimes use 0 as a sentinel value indicating that no control
+ * segment is known to exist, so avoid using that value for a real
+ * control segment.
+ */
for (;;)
{
Assert(dsm_control_address == NULL);
Assert(dsm_control_mapped_size == 0);
dsm_control_handle = random();
+ if (dsm_control_handle == 0)
+ continue;
if (dsm_impl_op(DSM_OP_CREATE, dsm_control_handle, segsize,
&dsm_control_impl_private, &dsm_control_address,
&dsm_control_mapped_size, ERROR))
break;
}
dsm_control = dsm_control_address;
- on_shmem_exit(dsm_postmaster_shutdown, 0);
+ on_shmem_exit(dsm_postmaster_shutdown, PointerGetDatum(shim));
elog(DEBUG2,
"created dynamic shared memory control segment %u (%zu bytes)",
dsm_control_handle, segsize);
- dsm_write_state_file(dsm_control_handle);
+ shim->dsm_control = dsm_control_handle;
/* Initialize control segment. */
dsm_control->magic = PG_DYNSHMEM_CONTROL_MAGIC;
@@ -216,8 +205,8 @@ dsm_postmaster_startup(void)
* invocation still exists. If so, remove the dynamic shared memory
* segments to which it refers, and then the control segment itself.
*/
-static void
-dsm_cleanup_using_control_segment(void)
+void
+dsm_cleanup_using_control_segment(dsm_handle old_control_handle)
{
void *mapped_address = NULL;
void *junk_mapped_address = NULL;
@@ -227,14 +216,10 @@ dsm_cleanup_using_control_segment(void)
Size junk_mapped_size = 0;
uint32 nitems;
uint32 i;
- dsm_handle old_control_handle;
dsm_control_header *old_control;
- /*
- * Read the state file. If it doesn't exist or is empty, there's nothing
- * more to do.
- */
- if (!dsm_read_state_file(&old_control_handle))
+ /* If dynamic shared memory is disabled, there's nothing to do. */
+ if (dynamic_shared_memory_type == DSM_IMPL_NONE)
return;
/*
@@ -347,111 +332,6 @@ dsm_cleanup_for_mmap(void)
}
/*
- * Read and parse the state file.
- *
- * If the state file is empty or the contents are garbled, it probably means
- * that the operating system rebooted before the data written by the previous
- * postmaster made it to disk. In that case, we can just ignore it; any shared
- * memory from before the reboot should be gone anyway.
- */
-static bool
-dsm_read_state_file(dsm_handle *h)
-{
- int statefd;
- char statebuf[PG_DYNSHMEM_STATE_BUFSIZ];
- int nbytes = 0;
- char *endptr,
- *s;
- dsm_handle handle;
-
- /* Read the state file to get the ID of the old control segment. */
- statefd = BasicOpenFile(PG_DYNSHMEM_STATE_FILE, O_RDONLY | PG_BINARY, 0);
- if (statefd < 0)
- {
- if (errno == ENOENT)
- return false;
- ereport(ERROR,
- (errcode_for_file_access(),
- errmsg("could not open file \"%s\": %m",
- PG_DYNSHMEM_STATE_FILE)));
- }
- nbytes = read(statefd, statebuf, PG_DYNSHMEM_STATE_BUFSIZ - 1);
- if (nbytes < 0)
- {
- close(statefd);
- ereport(ERROR,
- (errcode_for_file_access(),
- errmsg("could not read file \"%s\": %m",
- PG_DYNSHMEM_STATE_FILE)));
- }
- /* make sure buffer is NUL terminated */
- statebuf[nbytes] = '\0';
- close(statefd);
-
- /*
- * We expect to find the handle of the old control segment here,
- * on a line by itself.
- */
- handle = strtoul(statebuf, &endptr, 10);
- for (s = endptr; *s == ' ' || *s == '\t'; ++s)
- ;
- if (*s != '\n' && *s != '\0')
- return false;
-
- /* Looks good. */
- *h = handle;
- return true;
-}
-
-/*
- * Write our control segment handle to the state file, so that if the
- * postmaster is killed without running it's on_shmem_exit hooks, the
- * next postmaster can clean things up after restart.
- */
-static void
-dsm_write_state_file(dsm_handle h)
-{
- int statefd;
- char statebuf[PG_DYNSHMEM_STATE_BUFSIZ];
- int nbytes;
-
- /* Create or truncate the file. */
- statefd = open(PG_DYNSHMEM_NEW_STATE_FILE,
- O_RDWR | O_CREAT | O_TRUNC | PG_BINARY, 0600);
- if (statefd < 0)
- ereport(ERROR,
- (errcode_for_file_access(),
- errmsg("could not create file \"%s\": %m",
- PG_DYNSHMEM_NEW_STATE_FILE)));
-
- /* Write contents. */
- snprintf(statebuf, PG_DYNSHMEM_STATE_BUFSIZ, "%u\n", dsm_control_handle);
- nbytes = strlen(statebuf);
- if (write(statefd, statebuf, nbytes) != nbytes)
- {
- if (errno == 0)
- errno = ENOSPC; /* if no error signalled, assume no space */
- ereport(ERROR,
- (errcode_for_file_access(),
- errmsg("could not write file \"%s\": %m",
- PG_DYNSHMEM_NEW_STATE_FILE)));
- }
-
- /* Close file. */
- close(statefd);
-
- /*
- * Atomically rename file into place, so that no one ever sees a partially
- * written state file.
- */
- if (rename(PG_DYNSHMEM_NEW_STATE_FILE, PG_DYNSHMEM_STATE_FILE) < 0)
- ereport(ERROR,
- (errcode_for_file_access(),
- errmsg("could not rename file \"%s\": %m",
- PG_DYNSHMEM_NEW_STATE_FILE)));
-}
-
-/*
* At shutdown time, we iterate over the control segment and remove all
* remaining dynamic shared memory segments. We avoid throwing errors here;
* the postmaster is shutting down either way, and this is just non-critical
@@ -466,6 +346,7 @@ dsm_postmaster_shutdown(int code, Datum arg)
void *junk_mapped_address = NULL;
void *junk_impl_private = NULL;
Size junk_mapped_size = 0;
+ PGShmemHeader *shim = (PGShmemHeader *) DatumGetPointer(arg);
/*
* If some other backend exited uncleanly, it might have corrupted the
@@ -510,13 +391,7 @@ dsm_postmaster_shutdown(int code, Datum arg)
&dsm_control_impl_private, &dsm_control_address,
&dsm_control_mapped_size, LOG);
dsm_control = dsm_control_address;
-
- /* And, finally, remove the state file. */
- if (unlink(PG_DYNSHMEM_STATE_FILE) < 0)
- ereport(LOG,
- (errcode_for_file_access(),
- errmsg("could not unlink file \"%s\": %m",
- PG_DYNSHMEM_STATE_FILE)));
+ shim->dsm_control = 0;
}
/*
@@ -536,25 +411,18 @@ dsm_backend_startup(void)
#ifdef EXEC_BACKEND
{
- dsm_handle control_handle;
void *control_address = NULL;
- /* Read the control segment information from the state file. */
- if (!dsm_read_state_file(&control_handle))
- ereport(ERROR,
- (errcode(ERRCODE_INTERNAL_ERROR),
- errmsg("could not parse dynamic shared memory state file")));
-
/* Attach control segment. */
- dsm_impl_op(DSM_OP_ATTACH, control_handle, 0,
+ Assert(dsm_control_handle != 0);
+ dsm_impl_op(DSM_OP_ATTACH, dsm_control_handle, 0,
&dsm_control_impl_private, &control_address,
&dsm_control_mapped_size, ERROR);
- dsm_control_handle = control_handle;
dsm_control = control_address;
/* If control segment doesn't look sane, something is badly wrong. */
if (!dsm_control_segment_sane(dsm_control, dsm_control_mapped_size))
{
- dsm_impl_op(DSM_OP_DETACH, control_handle, 0,
+ dsm_impl_op(DSM_OP_DETACH, dsm_control_handle, 0,
&dsm_control_impl_private, &control_address,
&dsm_control_mapped_size, WARNING);
ereport(FATAL,
@@ -567,6 +435,20 @@ dsm_backend_startup(void)
dsm_init_done = true;
}
+#ifdef EXEC_BACKEND
+/*
+ * When running under EXEC_BACKEND, we get a callback here when the main
+ * shared memory segment is re-attached, so that we can record the control
+ * handle retrieved from it.
+ */
+void
+dsm_set_control_handle(dsm_handle h)
+{
+ Assert(dsm_control_handle == 0 && h != 0);
+ dsm_control_handle = h;
+}
+#endif
+
/*
* Create a new dynamic shared memory segment.
*/
diff --git a/src/backend/storage/ipc/ipci.c b/src/backend/storage/ipc/ipci.c
index c392d4fa228..4290d2dc81d 100644
--- a/src/backend/storage/ipc/ipci.c
+++ b/src/backend/storage/ipc/ipci.c
@@ -90,6 +90,8 @@ RequestAddinShmemSpace(Size size)
void
CreateSharedMemoryAndSemaphores(bool makePrivate, int port)
{
+ PGShmemHeader *shim = NULL;
+
if (!IsUnderPostmaster)
{
PGShmemHeader *seghdr;
@@ -149,7 +151,7 @@ CreateSharedMemoryAndSemaphores(bool makePrivate, int port)
/*
* Create the shmem segment
*/
- seghdr = PGSharedMemoryCreate(size, makePrivate, port);
+ seghdr = PGSharedMemoryCreate(size, makePrivate, port, &shim);
InitShmemAccess(seghdr);
@@ -254,7 +256,7 @@ CreateSharedMemoryAndSemaphores(bool makePrivate, int port)
/* Initialize dynamic shared memory facilities. */
if (!IsUnderPostmaster)
- dsm_postmaster_startup();
+ dsm_postmaster_startup(shim);
/*
* Now give loadable modules a chance to set up their shmem allocations
diff --git a/src/include/storage/dsm.h b/src/include/storage/dsm.h
index e4669a1e3c1..272787adc6b 100644
--- a/src/include/storage/dsm.h
+++ b/src/include/storage/dsm.h
@@ -18,10 +18,16 @@
typedef struct dsm_segment dsm_segment;
/* Startup and shutdown functions. */
-extern void dsm_postmaster_startup(void);
+struct PGShmemHeader; /* avoid including pg_shmem.h */
+extern void dsm_cleanup_using_control_segment(dsm_handle old_control_handle);
+extern void dsm_postmaster_startup(struct PGShmemHeader *);
extern void dsm_backend_shutdown(void);
extern void dsm_detach_all(void);
+#ifdef EXEC_BACKEND
+extern void dsm_set_control_handle(dsm_handle h);
+#endif
+
/* Functions that create, update, or remove mappings. */
extern dsm_segment *dsm_create(Size size);
extern dsm_segment *dsm_attach(dsm_handle h);
diff --git a/src/include/storage/pg_shmem.h b/src/include/storage/pg_shmem.h
index 0dc960b597f..ab28ebee846 100644
--- a/src/include/storage/pg_shmem.h
+++ b/src/include/storage/pg_shmem.h
@@ -24,6 +24,8 @@
#ifndef PG_SHMEM_H
#define PG_SHMEM_H
+#include "storage/dsm_impl.h"
+
typedef struct PGShmemHeader /* standard header for all Postgres shmem */
{
int32 magic; /* magic # to identify Postgres segments */
@@ -31,6 +33,7 @@ typedef struct PGShmemHeader /* standard header for all Postgres shmem */
pid_t creatorPID; /* PID of creating process */
Size totalsize; /* total size of segment */
Size freeoffset; /* offset to first free space */
+ dsm_handle dsm_control; /* ID of dynamic shared memory control seg */
void *index; /* pointer to ShmemIndex table */
#ifndef WIN32 /* Windows doesn't have useful inode#s */
dev_t device; /* device data directory is on */
@@ -61,7 +64,7 @@ extern void PGSharedMemoryReAttach(void);
#endif
extern PGShmemHeader *PGSharedMemoryCreate(Size size, bool makePrivate,
- int port);
+ int port, PGShmemHeader **shim);
extern bool PGSharedMemoryIsInUse(unsigned long id1, unsigned long id2);
extern void PGSharedMemoryDetach(void);
generated by cgit v1.2.3 (git 2.25.1) at 2025-05-21 00:18:43 +0000