diff options
Diffstat (limited to 'storage/bdb/os/os_map.c')
| -rw-r--r-- | storage/bdb/os/os_map.c | 443 |
1 files changed, 443 insertions, 0 deletions
diff --git a/storage/bdb/os/os_map.c b/storage/bdb/os/os_map.c new file mode 100644 index 00000000000..6d385b6a84d --- /dev/null +++ b/storage/bdb/os/os_map.c @@ -0,0 +1,443 @@ +/*- + * See the file LICENSE for redistribution information. + * + * Copyright (c) 1996-2002 + * Sleepycat Software. All rights reserved. + */ + +#include "db_config.h" + +#ifndef lint +static const char revid[] = "$Id: os_map.c,v 11.44 2002/07/12 18:56:51 bostic Exp $"; +#endif /* not lint */ + +#ifndef NO_SYSTEM_INCLUDES +#include <sys/types.h> +#ifdef HAVE_MMAP +#include <sys/mman.h> +#endif + +#ifdef HAVE_SHMGET +#include <sys/ipc.h> +#include <sys/shm.h> +#endif + +#include <string.h> +#endif + +#include "db_int.h" + +#ifdef HAVE_MMAP +static int __os_map __P((DB_ENV *, char *, DB_FH *, size_t, int, int, void **)); +#endif +#ifndef HAVE_SHMGET +static int __db_nosystemmem __P((DB_ENV *)); +#endif + +/* + * __os_r_sysattach -- + * Create/join a shared memory region. + * + * PUBLIC: int __os_r_sysattach __P((DB_ENV *, REGINFO *, REGION *)); + */ +int +__os_r_sysattach(dbenv, infop, rp) + DB_ENV *dbenv; + REGINFO *infop; + REGION *rp; +{ + if (F_ISSET(dbenv, DB_ENV_SYSTEM_MEM)) { + /* + * If the region is in system memory on UNIX, we use shmget(2). + * + * !!! + * There exist spinlocks that don't work in shmget memory, e.g., + * the HP/UX msemaphore interface. If we don't have locks that + * will work in shmget memory, we better be private and not be + * threaded. If we reach this point, we know we're public, so + * it's an error. + */ +#if defined(MUTEX_NO_SHMGET_LOCKS) + __db_err(dbenv, + "architecture does not support locks inside system shared memory"); + return (EINVAL); +#endif +#if defined(HAVE_SHMGET) + { + key_t segid; + int id, ret; + + /* + * We could potentially create based on REGION_CREATE_OK, but + * that's dangerous -- we might get crammed in sideways if + * some of the expected regions exist but others do not. Also, + * if the requested size differs from an existing region's + * actual size, then all sorts of nasty things can happen. + * Basing create solely on REGION_CREATE is much safer -- a + * recovery will get us straightened out. + */ + if (F_ISSET(infop, REGION_CREATE)) { + /* + * The application must give us a base System V IPC key + * value. Adjust that value based on the region's ID, + * and correct so the user's original value appears in + * the ipcs output. + */ + if (dbenv->shm_key == INVALID_REGION_SEGID) { + __db_err(dbenv, + "no base system shared memory ID specified"); + return (EINVAL); + } + segid = (key_t)(dbenv->shm_key + (infop->id - 1)); + + /* + * If map to an existing region, assume the application + * crashed and we're restarting. Delete the old region + * and re-try. If that fails, return an error, the + * application will have to select a different segment + * ID or clean up some other way. + */ + if ((id = shmget(segid, 0, 0)) != -1) { + (void)shmctl(id, IPC_RMID, NULL); + if ((id = shmget(segid, 0, 0)) != -1) { + __db_err(dbenv, + "shmget: key: %ld: shared system memory region already exists", + (long)segid); + return (EAGAIN); + } + } + if ((id = + shmget(segid, rp->size, IPC_CREAT | 0600)) == -1) { + ret = __os_get_errno(); + __db_err(dbenv, + "shmget: key: %ld: unable to create shared system memory region: %s", + (long)segid, strerror(ret)); + return (ret); + } + rp->segid = id; + } else + id = rp->segid; + + if ((infop->addr = shmat(id, NULL, 0)) == (void *)-1) { + infop->addr = NULL; + ret = __os_get_errno(); + __db_err(dbenv, + "shmat: id %d: unable to attach to shared system memory region: %s", + id, strerror(ret)); + return (ret); + } + + return (0); + } +#else + return (__db_nosystemmem(dbenv)); +#endif + } + +#ifdef HAVE_MMAP + { + DB_FH fh; + int ret; + + /* + * Try to open/create the shared region file. We DO NOT need to ensure + * that multiple threads/processes attempting to simultaneously create + * the region are properly ordered, our caller has already taken care + * of that. + */ + if ((ret = __os_open(dbenv, infop->name, + DB_OSO_REGION | DB_OSO_DIRECT | + (F_ISSET(infop, REGION_CREATE_OK) ? DB_OSO_CREATE : 0), + infop->mode, &fh)) != 0) + __db_err(dbenv, "%s: %s", infop->name, db_strerror(ret)); + + /* + * If we created the file, grow it to its full size before mapping + * it in. We really want to avoid touching the buffer cache after + * mmap(2) is called, doing anything else confuses the hell out of + * systems without merged VM/buffer cache systems, or, more to the + * point, *badly* merged VM/buffer cache systems. + */ + if (ret == 0 && F_ISSET(infop, REGION_CREATE)) + ret = __db_fileinit(dbenv, + &fh, rp->size, F_ISSET(dbenv, DB_ENV_REGION_INIT) ? 1 : 0); + + /* Map the file in. */ + if (ret == 0) + ret = __os_map(dbenv, + infop->name, &fh, rp->size, 1, 0, &infop->addr); + + if (F_ISSET(&fh, DB_FH_VALID)) + (void)__os_closehandle(dbenv, &fh); + + return (ret); + } +#else + COMPQUIET(infop, NULL); + COMPQUIET(rp, NULL); + __db_err(dbenv, + "architecture lacks mmap(2), shared environments not possible"); + return (__db_eopnotsup(dbenv)); +#endif +} + +/* + * __os_r_sysdetach -- + * Detach from a shared memory region. + * + * PUBLIC: int __os_r_sysdetach __P((DB_ENV *, REGINFO *, int)); + */ +int +__os_r_sysdetach(dbenv, infop, destroy) + DB_ENV *dbenv; + REGINFO *infop; + int destroy; +{ + REGION *rp; + + rp = infop->rp; + + if (F_ISSET(dbenv, DB_ENV_SYSTEM_MEM)) { +#ifdef HAVE_SHMGET + int ret, segid; + + /* + * We may be about to remove the memory referenced by rp, + * save the segment ID, and (optionally) wipe the original. + */ + segid = rp->segid; + if (destroy) + rp->segid = INVALID_REGION_SEGID; + + if (shmdt(infop->addr) != 0) { + ret = __os_get_errno(); + __db_err(dbenv, "shmdt: %s", strerror(ret)); + return (ret); + } + + if (destroy && shmctl(segid, IPC_RMID, + NULL) != 0 && (ret = __os_get_errno()) != EINVAL) { + __db_err(dbenv, + "shmctl: id %ld: unable to delete system shared memory region: %s", + segid, strerror(ret)); + return (ret); + } + + return (0); +#else + return (__db_nosystemmem(dbenv)); +#endif + } + +#ifdef HAVE_MMAP +#ifdef HAVE_MUNLOCK + if (F_ISSET(dbenv, DB_ENV_LOCKDOWN)) + (void)munlock(infop->addr, rp->size); +#endif + if (munmap(infop->addr, rp->size) != 0) { + int ret; + + ret = __os_get_errno(); + __db_err(dbenv, "munmap: %s", strerror(ret)); + return (ret); + } + + if (destroy && __os_region_unlink(dbenv, infop->name) != 0) + return (__os_get_errno()); + + return (0); +#else + COMPQUIET(destroy, 0); + return (EINVAL); +#endif +} + +/* + * __os_mapfile -- + * Map in a shared memory file. + * + * PUBLIC: int __os_mapfile __P((DB_ENV *, + * PUBLIC: char *, DB_FH *, size_t, int, void **)); + */ +int +__os_mapfile(dbenv, path, fhp, len, is_rdonly, addrp) + DB_ENV *dbenv; + char *path; + DB_FH *fhp; + int is_rdonly; + size_t len; + void **addrp; +{ +#if defined(HAVE_MMAP) && !defined(HAVE_QNX) + return (__os_map(dbenv, path, fhp, len, 0, is_rdonly, addrp)); +#else + COMPQUIET(dbenv, NULL); + COMPQUIET(path, NULL); + COMPQUIET(fhp, NULL); + COMPQUIET(is_rdonly, 0); + COMPQUIET(len, 0); + COMPQUIET(addrp, NULL); + return (EINVAL); +#endif +} + +/* + * __os_unmapfile -- + * Unmap the shared memory file. + * + * PUBLIC: int __os_unmapfile __P((DB_ENV *, void *, size_t)); + */ +int +__os_unmapfile(dbenv, addr, len) + DB_ENV *dbenv; + void *addr; + size_t len; +{ + /* If the user replaced the map call, call through their interface. */ + if (DB_GLOBAL(j_unmap) != NULL) + return (DB_GLOBAL(j_unmap)(addr, len)); + +#ifdef HAVE_MMAP +#ifdef HAVE_MUNLOCK + if (F_ISSET(dbenv, DB_ENV_LOCKDOWN)) + while (munlock(addr, len) != 0 && __os_get_errno() == EINTR) + ; +#else + COMPQUIET(dbenv, NULL); +#endif + { + int ret; + + while ((ret = munmap(addr, len)) != 0 && + __os_get_errno() == EINTR) + ; + return (ret ? __os_get_errno() : 0); + } +#else + COMPQUIET(dbenv, NULL); + + return (EINVAL); +#endif +} + +#ifdef HAVE_MMAP +/* + * __os_map -- + * Call the mmap(2) function. + */ +static int +__os_map(dbenv, path, fhp, len, is_region, is_rdonly, addrp) + DB_ENV *dbenv; + char *path; + DB_FH *fhp; + int is_region, is_rdonly; + size_t len; + void **addrp; +{ + void *p; + int flags, prot, ret; + + /* If the user replaced the map call, call through their interface. */ + if (DB_GLOBAL(j_map) != NULL) + return (DB_GLOBAL(j_map) + (path, len, is_region, is_rdonly, addrp)); + + /* + * If it's read-only, it's private, and if it's not, it's shared. + * Don't bother with an additional parameter. + */ + flags = is_rdonly ? MAP_PRIVATE : MAP_SHARED; + +#ifdef MAP_FILE + /* + * Historically, MAP_FILE was required for mapping regular files, + * even though it was the default. Some systems have it, some + * don't, some that have it set it to 0. + */ + flags |= MAP_FILE; +#endif + + /* + * I know of no systems that implement the flag to tell the system + * that the region contains semaphores, but it's not an unreasonable + * thing to do, and has been part of the design since forever. I + * don't think anyone will object, but don't set it for read-only + * files, it doesn't make sense. + */ +#ifdef MAP_HASSEMAPHORE + if (is_region && !is_rdonly) + flags |= MAP_HASSEMAPHORE; +#else + COMPQUIET(is_region, 0); +#endif + + prot = PROT_READ | (is_rdonly ? 0 : PROT_WRITE); + + /* + * XXX + * Work around a bug in the VMS V7.1 mmap() implementation. To map + * a file into memory on VMS it needs to be opened in a certain way, + * originally. To get the file opened in that certain way, the VMS + * mmap() closes the file and re-opens it. When it does this, it + * doesn't flush any caches out to disk before closing. The problem + * this causes us is that when the memory cache doesn't get written + * out, the file isn't big enough to match the memory chunk and the + * mmap() call fails. This call to fsync() fixes the problem. DEC + * thinks this isn't a bug because of language in XPG5 discussing user + * responsibility for on-disk and in-memory synchronization. + */ +#ifdef VMS + if (__os_fsync(dbenv, fhp) == -1) + return (__os_get_errno()); +#endif + + /* MAP_FAILED was not defined in early mmap implementations. */ +#ifndef MAP_FAILED +#define MAP_FAILED -1 +#endif + if ((p = mmap(NULL, + len, prot, flags, fhp->fd, (off_t)0)) == (void *)MAP_FAILED) { + ret = __os_get_errno(); + __db_err(dbenv, "mmap: %s", strerror(ret)); + return (ret); + } + +#ifdef HAVE_MLOCK + /* + * If it's a region, we want to make sure that the memory isn't paged. + * For example, Solaris will page large mpools because it thinks that + * I/O buffer memory is more important than we are. The mlock system + * call may or may not succeed (mlock is restricted to the super-user + * on some systems). Currently, the only other use of mmap in DB is + * to map read-only databases -- we don't want them paged, either, so + * the call isn't conditional. + */ + if (F_ISSET(dbenv, DB_ENV_LOCKDOWN) && mlock(p, len) != 0) { + ret = __os_get_errno(); + (void)munmap(p, len); + __db_err(dbenv, "mlock: %s", strerror(ret)); + return (ret); + } +#else + COMPQUIET(dbenv, NULL); +#endif + + *addrp = p; + return (0); +} +#endif + +#ifndef HAVE_SHMGET +/* + * __db_nosystemmem -- + * No system memory environments error message. + */ +static int +__db_nosystemmem(dbenv) + DB_ENV *dbenv; +{ + __db_err(dbenv, + "architecture doesn't support environments in system memory"); + return (__db_eopnotsup(dbenv)); +} +#endif |