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postgresql/src/include/storage/pg_shmem.h

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Create an internal semaphore API that is not tied to SysV semaphores. As proof of concept, provide an alternate implementation based on POSIX semaphores. Also push the SysV shared-memory implementation into a separate file so that it can be replaced conveniently.
2002-05-05 02:03:29 +02:00
/*-------------------------------------------------------------------------
*
* pg_shmem.h
* Platform-independent API for shared memory support.
*
* Every port is expected to support shared memory with approximately
* SysV-ish semantics; in particular, a memory block is not anonymous
* but has an ID, and we must be able to tell whether there are any
* remaining processes attached to a block of a specified ID.
*
* To simplify life for the SysV implementation, the ID is assumed to
* consist of two unsigned long values (these are key and ID in SysV
pgindent run for 9.4 This includes removing tabs after periods in C comments, which was applied to back branches, so this change should not effect backpatching.
2014-05-06 18:12:18 +02:00
* terms). Other platforms may ignore the second value if they need
Create an internal semaphore API that is not tied to SysV semaphores. As proof of concept, provide an alternate implementation based on POSIX semaphores. Also push the SysV shared-memory implementation into a separate file so that it can be replaced conveniently.
2002-05-05 02:03:29 +02:00
* only one ID number.
*
*
Update copyright for 2015 Backpatch certain files through 9.0
2015-01-06 17:43:47 +01:00
* Portions Copyright (c) 1996-2015, PostgreSQL Global Development Group
Create an internal semaphore API that is not tied to SysV semaphores. As proof of concept, provide an alternate implementation based on POSIX semaphores. Also push the SysV shared-memory implementation into a separate file so that it can be replaced conveniently.
2002-05-05 02:03:29 +02:00
* Portions Copyright (c) 1994, Regents of the University of California
*
Remove cvs keywords from all files.
2010-09-20 22:08:53 +02:00
* src/include/storage/pg_shmem.h
Create an internal semaphore API that is not tied to SysV semaphores. As proof of concept, provide an alternate implementation based on POSIX semaphores. Also push the SysV shared-memory implementation into a separate file so that it can be replaced conveniently.
2002-05-05 02:03:29 +02:00
*
*-------------------------------------------------------------------------
*/
#ifndef PG_SHMEM_H
#define PG_SHMEM_H
Get rid of the dynamic shared memory state file. Instead of storing the ID of the dynamic shared memory control segment in a file within the data directory, store it in the main control segment. This avoids a number of nasty corner cases, most seriously that doing an online backup and then using it on the same machine (e.g. to fire up a standby) would result in the standby clobbering all of the master's dynamic shared memory segments. Per complaints from Heikki Linnakangas, Fujii Masao, and Tom Lane.
2014-04-08 17:39:55 +02:00
#include "storage/dsm_impl.h"
Create an internal semaphore API that is not tied to SysV semaphores. As proof of concept, provide an alternate implementation based on POSIX semaphores. Also push the SysV shared-memory implementation into a separate file so that it can be replaced conveniently.
2002-05-05 02:03:29 +02:00
typedef struct PGShmemHeader /* standard header for all Postgres shmem */
{
int32 magic; /* magic # to identify Postgres segments */
Rearrange backend startup sequence so that ShmemIndexLock can become an LWLock instead of a spinlock. This hardly matters on Unix machines but should improve startup performance on Windows (or any port using EXEC_BACKEND). Per previous discussion.
2006-01-04 22:06:32 +01:00
#define PGShmemMagic 679834894
Create an internal semaphore API that is not tied to SysV semaphores. As proof of concept, provide an alternate implementation based on POSIX semaphores. Also push the SysV shared-memory implementation into a separate file so that it can be replaced conveniently.
2002-05-05 02:03:29 +02:00
pid_t creatorPID; /* PID of creating process */
Convert the arithmetic for shared memory size calculation from 'int' to 'Size' (that is, size_t), and install overflow detection checks in it. This allows us to remove the former arbitrary restrictions on NBuffers etc. It won't make any difference in a 32-bit machine, but in a 64-bit machine you could theoretically have terabytes of shared buffers. (How efficiently we could manage 'em remains to be seen.) Similarly, num_temp_buffers, work_mem, and maintenance_work_mem can be set above 2Gb on a 64-bit machine. Original patch from Koichi Suzuki, additional work by moi.
2005-08-21 01:26:37 +02:00
Size totalsize; /* total size of segment */
Size freeoffset; /* offset to first free space */
Get rid of the dynamic shared memory state file. Instead of storing the ID of the dynamic shared memory control segment in a file within the data directory, store it in the main control segment. This avoids a number of nasty corner cases, most seriously that doing an online backup and then using it on the same machine (e.g. to fire up a standby) would result in the standby clobbering all of the master's dynamic shared memory segments. Per complaints from Heikki Linnakangas, Fujii Masao, and Tom Lane.
2014-04-08 17:39:55 +02:00
dsm_handle dsm_control; /* ID of dynamic shared memory control seg */
Remove the last vestiges of the MAKE_PTR/MAKE_OFFSET mechanism. We haven't allowed different processes to have different addresses for the shmem segment in quite a long time, but there were still a few places left that used the old coding convention. Clean them up to reduce confusion and improve the compiler's ability to detect pointer type mismatches. Kris Jurka
2008-11-02 22:24:52 +01:00
void *index; /* pointer to ShmemIndex table */
Put in place some defenses against being fooled by accidental match of shared memory segment ID. If we can't access the existing shmem segment, it must not be relevant to our data directory. If we can access it, then attach to it and check for an actual match to the data directory. This should avoid some cases of failure-to-restart-after-boot without introducing any significant risk of failing to detect a still-running old backend.
2004-11-09 22:30:18 +01:00
#ifndef WIN32 /* Windows doesn't have useful inode#s */
dev_t device; /* device data directory is on */
ino_t inode; /* inode number of data directory */
#endif
Create an internal semaphore API that is not tied to SysV semaphores. As proof of concept, provide an alternate implementation based on POSIX semaphores. Also push the SysV shared-memory implementation into a separate file so that it can be replaced conveniently.
2002-05-05 02:03:29 +02:00
} PGShmemHeader;
Allow using huge TLB pages on Linux (MAP_HUGETLB) This patch adds an option, huge_tlb_pages, which allows requesting the shared memory segment to be allocated using huge pages, by using the MAP_HUGETLB flag in mmap(). This can improve performance. The default is 'try', which means that we will attempt using huge pages, and fall back to non-huge pages if it doesn't work. Currently, only Linux has MAP_HUGETLB. On other platforms, the default 'try' behaves the same as 'off'. In the passing, don't try to round the mmap() size to a multiple of pagesize. mmap() doesn't require that, and there's no particular reason for PostgreSQL to do that either. When using MAP_HUGETLB, however, round the request size up to nearest 2MB boundary. This is to work around a bug in some Linux kernel versions, but also to avoid wasting memory, because the kernel will round the size up anyway. Many people were involved in writing this patch, including Christian Kruse, Richard Poole, Abhijit Menon-Sen, reviewed by Peter Geoghegan, Andres Freund and me.
2014-01-29 12:44:45 +01:00
/* GUC variable */
pgindent run for 9.4 This includes removing tabs after periods in C comments, which was applied to back branches, so this change should not effect backpatching.
2014-05-06 18:12:18 +02:00
extern int huge_pages;
Allow using huge TLB pages on Linux (MAP_HUGETLB) This patch adds an option, huge_tlb_pages, which allows requesting the shared memory segment to be allocated using huge pages, by using the MAP_HUGETLB flag in mmap(). This can improve performance. The default is 'try', which means that we will attempt using huge pages, and fall back to non-huge pages if it doesn't work. Currently, only Linux has MAP_HUGETLB. On other platforms, the default 'try' behaves the same as 'off'. In the passing, don't try to round the mmap() size to a multiple of pagesize. mmap() doesn't require that, and there's no particular reason for PostgreSQL to do that either. When using MAP_HUGETLB, however, round the request size up to nearest 2MB boundary. This is to work around a bug in some Linux kernel versions, but also to avoid wasting memory, because the kernel will round the size up anyway. Many people were involved in writing this patch, including Christian Kruse, Richard Poole, Abhijit Menon-Sen, reviewed by Peter Geoghegan, Andres Freund and me.
2014-01-29 12:44:45 +01:00
Rename huge_tlb_pages to huge_pages, and improve docs. Christian Kruse
2014-03-03 19:52:48 +01:00
/* Possible values for huge_pages */
Allow using huge TLB pages on Linux (MAP_HUGETLB) This patch adds an option, huge_tlb_pages, which allows requesting the shared memory segment to be allocated using huge pages, by using the MAP_HUGETLB flag in mmap(). This can improve performance. The default is 'try', which means that we will attempt using huge pages, and fall back to non-huge pages if it doesn't work. Currently, only Linux has MAP_HUGETLB. On other platforms, the default 'try' behaves the same as 'off'. In the passing, don't try to round the mmap() size to a multiple of pagesize. mmap() doesn't require that, and there's no particular reason for PostgreSQL to do that either. When using MAP_HUGETLB, however, round the request size up to nearest 2MB boundary. This is to work around a bug in some Linux kernel versions, but also to avoid wasting memory, because the kernel will round the size up anyway. Many people were involved in writing this patch, including Christian Kruse, Richard Poole, Abhijit Menon-Sen, reviewed by Peter Geoghegan, Andres Freund and me.
2014-01-29 12:44:45 +01:00
typedef enum
{
Rename huge_tlb_pages to huge_pages, and improve docs. Christian Kruse
2014-03-03 19:52:48 +01:00
HUGE_PAGES_OFF,
HUGE_PAGES_ON,
HUGE_PAGES_TRY
pgindent run for 9.4 This includes removing tabs after periods in C comments, which was applied to back branches, so this change should not effect backpatching.
2014-05-06 18:12:18 +02:00
} HugePagesType;
Create an internal semaphore API that is not tied to SysV semaphores. As proof of concept, provide an alternate implementation based on POSIX semaphores. Also push the SysV shared-memory implementation into a separate file so that it can be replaced conveniently.
2002-05-05 02:03:29 +02:00
Support 64-bit shared memory when building on 64-bit Windows. Tsutomu Yamada
2010-01-02 13:18:45 +01:00
#ifndef WIN32
Avoid assuming that type key_t is 32 bits, since it reportedly isn't on 64-bit Solaris. Use a non-system-dependent datatype for UsedShmemSegID, namely unsigned long (which we were already assuming could hold a shmem key anyway, cf RecordSharedMemoryInLockFile).
2003-12-01 23:15:38 +01:00
extern unsigned long UsedShmemSegID;
Support 64-bit shared memory when building on 64-bit Windows. Tsutomu Yamada
2010-01-02 13:18:45 +01:00
#else
extern HANDLE UsedShmemSegID;
#endif
Pass shared memory address on command line to exec'ed backend. Allow backends to attached to specified shared memory address.
2003-05-08 16:49:04 +02:00
extern void *UsedShmemSegAddr;
Refactor EXEC_BACKEND code so that postmaster child processes reattach to shared memory as soon as possible, ie, right after read_backend_variables. The effective difference from the original code is that this happens before instead of after read_nondefault_variables(), which loads GUC information and is apparently capable of expanding the backend's memory allocation more than you'd think it should. This should fix the failure-to-attach-to-shared-memory reports we've been seeing on Windows. Also clean up a few bits of unnecessarily grotty EXEC_BACKEND code.
2004-12-29 22:36:09 +01:00
Mark some more variables as static or include the appropriate header Detected by clang's -Wmissing-variable-declarations. From: Andres Freund <andres@anarazel.de>
2014-02-09 03:21:46 +01:00
#ifdef EXEC_BACKEND
Refactor EXEC_BACKEND code so that postmaster child processes reattach to shared memory as soon as possible, ie, right after read_backend_variables. The effective difference from the original code is that this happens before instead of after read_nondefault_variables(), which loads GUC information and is apparently capable of expanding the backend's memory allocation more than you'd think it should. This should fix the failure-to-attach-to-shared-memory reports we've been seeing on Windows. Also clean up a few bits of unnecessarily grotty EXEC_BACKEND code.
2004-12-29 22:36:09 +01:00
extern void PGSharedMemoryReAttach(void);
Pass shared memory id and socket descriptor number on command line for fork/exec.
2003-05-07 01:34:56 +02:00
#endif
Convert the arithmetic for shared memory size calculation from 'int' to 'Size' (that is, size_t), and install overflow detection checks in it. This allows us to remove the former arbitrary restrictions on NBuffers etc. It won't make any difference in a 32-bit machine, but in a 64-bit machine you could theoretically have terabytes of shared buffers. (How efficiently we could manage 'em remains to be seen.) Similarly, num_temp_buffers, work_mem, and maintenance_work_mem can be set above 2Gb on a 64-bit machine. Original patch from Koichi Suzuki, additional work by moi.
2005-08-21 01:26:37 +02:00
extern PGShmemHeader *PGSharedMemoryCreate(Size size, bool makePrivate,
Get rid of the dynamic shared memory state file. Instead of storing the ID of the dynamic shared memory control segment in a file within the data directory, store it in the main control segment. This avoids a number of nasty corner cases, most seriously that doing an online backup and then using it on the same machine (e.g. to fire up a standby) would result in the standby clobbering all of the master's dynamic shared memory segments. Per complaints from Heikki Linnakangas, Fujii Masao, and Tom Lane.
2014-04-08 17:39:55 +02:00
int port, PGShmemHeader **shim);
Create an internal semaphore API that is not tied to SysV semaphores. As proof of concept, provide an alternate implementation based on POSIX semaphores. Also push the SysV shared-memory implementation into a separate file so that it can be replaced conveniently.
2002-05-05 02:03:29 +02:00
extern bool PGSharedMemoryIsInUse(unsigned long id1, unsigned long id2);
Cause stats processes to detach from shared memory when started, so that they do not prevent the postmaster from deleting the shmem segment during a post-backend-crash restart cycle. Per recent discussion.
2003-11-07 22:55:50 +01:00
extern void PGSharedMemoryDetach(void);
Create an internal semaphore API that is not tied to SysV semaphores. As proof of concept, provide an alternate implementation based on POSIX semaphores. Also push the SysV shared-memory implementation into a separate file so that it can be replaced conveniently.
2002-05-05 02:03:29 +02:00
#endif /* PG_SHMEM_H */