os_region.c

00001 /*-
00002  * See the file LICENSE for redistribution information.
00003  *
00004  * Copyright (c) 1996, 1997, 1998, 1999, 2000
00005  * Sleepycat Software. All rights reserved.
00006  */
00007 
00008 #include "config.h"
00009 
00010 #ifndef lint
00011 static const char revid[] = "$Id: os__region_8c-source.html,v 1.1 2008年06月08日 10:21:27 sebdiaz Exp $";
00012 #endif /* not lint */
00013 
00014 #ifndef NO_SYSTEM_INCLUDES
00015 #include <sys/types.h>
00016 
00017 #include <errno.h>
00018 #endif
00019 
00020 #include "db_int.h"
00021 #include "os_jump.h"
00022 
00023 /*
00024  * CDB___os_r_attach --
00025  * Attach to a shared memory region.
00026  *
00027  * PUBLIC: int CDB___os_r_attach __P((DB_ENV *, REGINFO *, REGION *));
00028  */
00029 int
00030 CDB___os_r_attach(dbenv, infop, rp)
00031 DB_ENV *dbenv;
00032 REGINFO *infop;
00033 REGION *rp;
00034 {
00035 /* Round off the requested size for the underlying VM. */
00036 OS_VMROUNDOFF(rp->size);
00037 
00038 #ifdef DB_REGIONSIZE_MAX
00039 /* Some architectures have hard limits on the maximum region size. */
00040 if (rp->size > DB_REGIONSIZE_MAX) {
00041 CDB___db_err(dbenv, "region size %lu is too large; maximum is %lu",
00042 (u_long)rp->size, (u_long)DB_REGIONSIZE_MAX);
00043 return (EINVAL);
00044 }
00045 #endif
00046 
00047 /*
00048  * If a region is private, malloc the memory.
00049  *
00050  * !!!
00051  * If this fails because the region is too large to malloc, mmap(2)
00052  * using the MAP_ANON or MAP_ANONYMOUS flags would be an alternative.
00053  * I don't know of any architectures (yet!) where malloc is a problem.
00054  */
00055 if (F_ISSET(dbenv, DB_ENV_PRIVATE)) {
00056 #if defined(MUTEX_NO_MALLOC_LOCKS)
00057 /*
00058  * !!!
00059  * There exist spinlocks that don't work in malloc memory, e.g.,
00060  * the HP/UX msemaphore interface. If we don't have locks that
00061  * will work in malloc memory, we better not be private or not
00062  * be threaded.
00063  */
00064 if (F_ISSET(dbenv, DB_ENV_THREAD)) {
00065 CDB___db_err(dbenv, "%s",
00066 "architecture does not support locks inside process-local (malloc) memory");
00067 CDB___db_err(dbenv, "%s",
00068 "application may not specify both DB_PRIVATE and DB_THREAD");
00069 return (EINVAL);
00070 }
00071 #endif
00072 return (CDB___os_malloc(dbenv, rp->size, NULL, &infop->addr));
00073 }
00074 
00075 /* If the user replaced the map call, call through their interface. */
00076 if (CDB___db_jump.j_map != NULL)
00077 return (CDB___db_jump.j_map(infop->name,
00078 rp->size, 1, 0, &infop->addr));
00079 
00080 return (CDB___os_r_sysattach(dbenv, infop, rp));
00081 }
00082 
00083 /*
00084  * CDB___os_r_detach --
00085  * Detach from a shared memory region.
00086  *
00087  * PUBLIC: int CDB___os_r_detach __P((DB_ENV *, REGINFO *, int));
00088  */
00089 int
00090 CDB___os_r_detach(dbenv, infop, destroy)
00091 DB_ENV *dbenv;
00092 REGINFO *infop;
00093 int destroy;
00094 {
00095 REGION *rp;
00096 
00097 rp = infop->rp;
00098 
00099 /* If a region is private, free the memory. */
00100 if (F_ISSET(dbenv, DB_ENV_PRIVATE)) {
00101 CDB___os_free(infop->addr, rp->size);
00102 return (0);
00103 }
00104 
00105 /* If the user replaced the map call, call through their interface. */
00106 if (CDB___db_jump.j_unmap != NULL)
00107 return (CDB___db_jump.j_unmap(infop->addr, rp->size));
00108 
00109 return (CDB___os_r_sysdetach(dbenv, infop, destroy));
00110 }