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Add shared memory and semaphore routines for Win32.

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Also update copyright to be ours, with approval from Jan.
WIN32_DEV
Bruce Momjian 23 years ago
parent d670bf378c
commit 1a67e4869c
2 changed files with 359 additions and 0 deletions
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  1. 239
      src/backend/port/win32/sem.c
  2. 120
      src/backend/port/win32/shm.c

239
src/backend/port/win32/sem.c
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/*-------------------------------------------------------------------------
*
* sem.c
* Microsoft Windows Win32 Semaphores Emulation
*
* Portions Copyright (c) 1996-2002, PostgreSQL Global Development Group
*
*-------------------------------------------------------------------------
*/
#include "postgres.h"
#include "storage/shmem.h"
#include <errno.h>
typedef struct {
int m_numSems;
off_t m_semaphoreHandles; // offset from beginning of header
off_t m_semaphoreCounts; // offset from beginning of header
} win32_sem_set_hdr;
/* Control of a semaphore pool. The pool is an area in which we stored all
** the semIds of the pool. The first long is the number of semaphore
** allocated in the pool followed by semaphore handles
*/
int
semctl(int semId, int semNum, int flag, union semun semun)
{
win32_sem_set_hdr* the_set = (win32_sem_set_hdr*)MAKE_PTR(semId);
/* semNum might be 0 */
/* semun.array contains the sem initial values */
int* sem_counts = (int*)((off_t)the_set + the_set->m_semaphoreCounts);
/* Fix the count of all sem of the pool to semun.array */
if (flag == SETALL)
{
int i;
struct sembuf sops;
sops.sem_flg = IPC_NOWAIT;
for (i = 0; i < the_set->m_numSems; ++i) {
if (semun.array[i] == sem_counts[i])
continue; /* Nothing to do */
if (semun.array[i] < sem_counts[i])
sops.sem_op = -1;
else
sops.sem_op = 1;
sops.sem_num = i;
/* Quickly lock/unlock the semaphore (if we can) */
if (semop(semId, &sops, 1) < 0)
return -1;
}
return 1;
}
/* Fix the count of one semaphore to semun.val */
else if (flag == SETVAL)
{
if (semun.val != sem_counts[semNum]) {
struct sembuf sops;
sops.sem_flg = IPC_NOWAIT;
sops.sem_num = semNum;
if (semun.val < sem_counts[semNum])
sops.sem_op = -1;
else
sops.sem_op = 1;
/* Quickly lock/unlock the semaphore (if we can) */
if (semop(semId, &sops, 1) < 0)
return -1;
}
return 1;
}
/* Delete the pool */
else if (flag == IPC_RMID)
{
int i;
HANDLE* sem_handles = (HANDLE*)((off_t)the_set + the_set->m_semaphoreHandles);
/* Loop over all semaphore to delete them */
for (i = 0; i < the_set->m_numSems; ++i)
CloseHandle(sem_handles[i]);
return 1;
}
/* Get the current semaphore count */
else if (flag == GETNCNT)
{
return the_set->m_numSems;
}
/* Get the current semaphore count of the first semaphore in the pool */
else if (flag == GETVAL)
{
return sem_counts[semNum];
}
/* Other commands not yet supported */
else
{
errno = EINVAL;
return -1;
}
}
/* Find a pool id based on IPC key */
int
semget(int semKey, int semNum, int flags)
{
char semname[32];
char cur_num[20];
DWORD last_error;
char* num_part;
bool ans = true;
SECURITY_ATTRIBUTES sec_attrs;
HANDLE cur_handle;
bool found = false;
Size sem_set_size = sizeof(win32_sem_set_hdr) + semNum * (sizeof(HANDLE) + sizeof(int));
HANDLE* sem_handles = NULL;
int* sem_counts = NULL;
sec_attrs.nLength = sizeof(sec_attrs);
sec_attrs.lpSecurityDescriptor = NULL;
sec_attrs.bInheritHandle = TRUE;
sprintf(semname, "PG_SEMSET.%d.", semKey);
num_part = semname + strlen(semname);
strcpy(num_part, _itoa(_getpid() * -1, cur_num, 10)); /* For shared memory, include the pid */
win32_sem_set_hdr* new_set = (win32_sem_set_hdr*)ShmemInitStruct(semname, sem_set_size, &found);
if (found) {
/* This should *never* happen */
errno = EEXIST;
return -1;
}
new_set->m_numSems = semNum;
new_set->m_semaphoreHandles = sizeof(win32_sem_set_hdr); // array starts after header
new_set->m_semaphoreCounts = new_set->m_semaphoreHandles + (sizeof(HANDLE) * semNum);
sem_handles = (HANDLE*)((off_t)new_set + new_set->m_semaphoreHandles);
sem_counts = (int*)((off_t)new_set + new_set->m_semaphoreCounts);
for (int i=0; i<semNum && ans; ++i) {
strcpy(num_part, _itoa(i, cur_num, 10));
if (flags & IPC_CREAT)
cur_handle = CreateSemaphore(&sec_attrs, 0, 1, semname);
else
cur_handle = OpenSemaphore(SEMAPHORE_ALL_ACCESS, TRUE, semname);
sem_handles[i] = cur_handle;
last_error = GetLastError();
if (!cur_handle)
{
errno = EACCES;
ans = false;
}
else if (last_error == ERROR_ALREADY_EXISTS && (flags & (IPC_CREAT | IPC_EXCL)))
{
errno = EEXIST;
ans = false;
}
}
if (ans) {
return MAKE_OFFSET(new_set);
} else {
// Blow away what we've got right now...
for (int i=0; i<semNum; ++i) {
if (sem_handles[i])
CloseHandle(sem_handles[i]);
else
break;
}
return -1;
}
}
/* Acquire or release in the semaphore pool */
int
semop(int semId, struct sembuf * sops, int nsops)
{
win32_sem_set_hdr* the_set = (win32_sem_set_hdr*)MAKE_PTR(semId);
HANDLE* sem_handles = (HANDLE*)((off_t)the_set + the_set->m_semaphoreHandles);
int* sem_counts = (int*)((off_t)the_set + the_set->m_semaphoreCounts);
HANDLE cur_handle;
if (nsops != 1) {
/* Not supported (we return on 1st success, and don't cancel earlier ops) */
errno = E2BIG;
return -1;
}
cur_handle = sem_handles[sops[0].sem_num];
if (sops[0].sem_op == -1)
{
DWORD ret;
if (sops[0].sem_flg & IPC_NOWAIT)
ret = WaitForSingleObject(cur_handle, 0);
else
ret = WaitForSingleObject(cur_handle, INFINITE);
if (ret == WAIT_OBJECT_0) {
/* We got it! */
sem_counts[sops[0].sem_num]--;
return 0;
} else if (ret == WAIT_TIMEOUT)
/* Couldn't get it */
errno = EAGAIN;
else
errno = EIDRM;
}
else if (sops[0].sem_op > 0) {
/* Don't want the lock anymore */
sem_counts[sops[0].sem_num]++;
ReleaseSemaphore(cur_handle, sops[0].sem_op, NULL);
return 0;
}
else
/* Not supported */
errno = ERANGE;
/* If we get down here, then something is wrong */
return -1;
}

120
src/backend/port/win32/shm.c
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/*-------------------------------------------------------------------------
*
* shm.c
* Microsoft Windows Win32 Shared Memory Emulation
*
* Portions Copyright (c) 1996-2002, PostgreSQL Global Development Group
*
*-------------------------------------------------------------------------
*/
#include "postgres.h"
#include "windows.h"
#include <stdio.h>
#include <errno.h>
static DWORD s_segsize = 0;
/* Detach from a shared mem area based on its address */
int
shmdt(const void *shmaddr)
{
if (UnmapViewOfFile(shmaddr))
return 0;
else
return -1;
}
/* Attach to an existing area */
void *
shmat(int memId, void* shmaddr, int flag)
{
/* KEW_TODO -- shmat needs to count # attached to shared mem */
void *lpmem = MapViewOfFileEx((HANDLE)memId,
FILE_MAP_WRITE | FILE_MAP_READ,
0, 0, /* (DWORD)pshmdsc->segsize */ s_segsize, shmaddr);
if (lpmem == NULL) {
lpmem = (void *)-1;
errno = GetLastError();
}
return lpmem;
}
/* Control a shared mem area */
int
shmctl(int shmid, int flag, struct shmid_ds * dummy)
{
if (flag == IPC_RMID)
{
/* Delete the area */
CloseHandle((HANDLE)shmid);
return 0;
}
if (flag == IPC_STAT)
{
/* Can only test for if exists */
int hmap = shmget(shmid, 0, 0);
if (hmap < 0) {
/* Shared memory does not exist */
errno = EINVAL;
return -1;
}
else {
/* Shared memory does exist and must be in use */
shmctl(hmap, IPC_RMID, NULL); /* Release our hold on it */
errno = 0;
return 0;
}
}
errno = EINVAL;
return -1;
}
/* Get an area based on the IPC key */
int
shmget(int memKey, int size, int flag)
{
HANDLE hmap;
char szShareMem[32];
DWORD dwRet;
s_segsize = size;
sprintf(szShareMem, "sharemem.%d", memKey);
if (flag & IPC_CREAT) {
hmap = CreateFileMapping((HANDLE)0xFFFFFFFF, /* Use the swap file */
NULL,
PAGE_READWRITE, /* Memory is Read/Write */
0L, /* Size Upper 32 Bits */
(DWORD)s_segsize, /* Size Lower 32 bits*/
szShareMem);
}
else {
hmap = OpenFileMapping(FILE_MAP_ALL_ACCESS,
FALSE,
szShareMem);
if (!hmap) {
errno = ENOENT;
return -1;
}
}
dwRet = GetLastError();
if (dwRet == ERROR_ALREADY_EXISTS && hmap && (flag & (IPC_CREAT | IPC_EXCL))) {
/* Caller wanted to create the segment -- error if already exists */
CloseHandle(hmap);
errno = EEXIST;
return -1;
}
else if (!hmap)
{
/* Unable to get shared memory */
return -1;
}
return (int)hmap;
}
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