From a37195f686746eb5781c9fcbc81ba2f389602324 Mon Sep 17 00:00:00 2001 From: Howard Chu Date: Tue, 28 Jun 2011 14:22:22 -0700 Subject: [PATCH] Use shmat for lock region instead of mmap --- libraries/libmdb/mdb.c | 67 ++++++++++++++++++------------------------ 1 file changed, 29 insertions(+), 38 deletions(-) diff --git a/libraries/libmdb/mdb.c b/libraries/libmdb/mdb.c index 913de09561..a1a2d07a83 100644 --- a/libraries/libmdb/mdb.c +++ b/libraries/libmdb/mdb.c @@ -7,6 +7,8 @@ #ifdef HAVE_SYS_FILE_H #include #endif +#include +#include #include #include @@ -245,7 +247,7 @@ struct MDB_db { struct MDB_env { int me_fd; - int me_lfd; + key_t me_shmkey; #define MDB_FIXPADDING 0x01 /* internal */ uint32_t me_flags; int me_maxreaders; @@ -908,7 +910,7 @@ fail: } int -mdbenv_create(MDB_env **env, size_t size) +mdbenv_create(MDB_env **env) { MDB_env *e; @@ -1022,50 +1024,40 @@ mdbenv_reader_dest(void *ptr) int mdbenv_open(MDB_env *env, const char *path, unsigned int flags, mode_t mode) { - int oflags, rc, len; - char *lpath; - off_t size, rsize; - - len = strlen(path); - lpath = malloc(len + sizeof(".lock")); - sprintf(lpath, "%s.lock", path); - if ((env->me_lfd = open(lpath, O_RDWR | O_CREAT, mode)) == -1) + int oflags, rc, shmid; + off_t size; + + + if (F_ISSET(flags, MDB_RDONLY)) + oflags = O_RDONLY; + else + oflags = O_RDWR | O_CREAT | O_APPEND; + + if ((env->me_fd = open(path, oflags, mode)) == -1) return errno; - size = lseek(env->me_lfd, 0, SEEK_END); - rsize = (env->me_maxreaders-1) * sizeof(MDB_reader) + sizeof(MDB_txninfo); - if (size < rsize) { - if (ftruncate(env->me_lfd, rsize) != 0) { - rc = errno; - close(env->me_lfd); - return rc; + env->me_shmkey = ftok(path, 'm'); + size = (env->me_maxreaders-1) * sizeof(MDB_reader) + sizeof(MDB_txninfo); + shmid = shmget(env->me_shmkey, size, IPC_CREAT|IPC_EXCL|mode); + if (shmid == -1) { + if (errno == EEXIST) { + shmid = shmget(env->me_shmkey, size, IPC_CREAT|mode); + if (shmid == -1) + return errno; + env->me_txns = shmat(shmid, NULL, 0); + } else { + return errno; } } else { - rsize = size; - size = rsize - sizeof(MDB_txninfo); - env->me_maxreaders = size/sizeof(MDB_reader) + 1; - } - env->me_txns = mmap(0, rsize, PROT_READ|PROT_WRITE, MAP_SHARED, - env->me_lfd, 0); - if (env->me_txns == MAP_FAILED) - return errno; - if (size == 0) { pthread_mutexattr_t mattr; + env->me_txns = shmat(shmid, NULL, 0); pthread_mutexattr_init(&mattr); pthread_mutexattr_setpshared(&mattr, PTHREAD_PROCESS_SHARED); pthread_mutex_init(&env->me_txns->mt_mutex, &mattr); pthread_mutex_init(&env->me_txns->mt_wmutex, &mattr); } - if (F_ISSET(flags, MDB_RDONLY)) - oflags = O_RDONLY; - else - oflags = O_RDWR | O_CREAT | O_APPEND; - - if ((env->me_fd = open(path, oflags, mode)) == -1) - return errno; - if ((rc = mdbenv_open2(env, flags)) != MDB_SUCCESS) { close(env->me_fd); env->me_fd = -1; @@ -1092,10 +1084,8 @@ mdbenv_close(MDB_env *env) } close(env->me_fd); if (env->me_txns) { - size_t size = (env->me_maxreaders-1) * sizeof(MDB_reader) + sizeof(MDB_txninfo); - munmap(env->me_txns, size); + shmdt(env->me_txns); } - close(env->me_lfd); free(env); } @@ -2507,8 +2497,9 @@ mdbenv_compact(MDB_env *env) return rc; } - rc = mdbenv_create(&envc, env->me_mapsize); + rc = mdbenv_create(&envc); if (rc) goto failed; + rc = mdbenv_set_mapsize(envc, env->me_mapsize); envc->me_fd = fd; rc = mdbenv_open2(envc, env->me_flags); -- 2.39.5