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Use an environment directory

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Go back to using an mmap'd lock file
This commit is contained in:
Howard Chu 2011-07-02 20:15:54 -07:00
parent 5a72c6a294
commit bc0ca49d16
2 changed files with 138 additions and 46 deletions
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3
libraries/libmdb/Makefile
View File

@ -7,9 +7,10 @@ LDLIBS =
all: mtest mdb_stat
clean:
rm -f mtest mdb_stat *.[ao] *~ testdb
rm -rf mtest mdb_stat *.[ao] *~ testdb
test: all
mkdir testdb
./mtest && ./mdb_stat testdb
mdb_stat: mdb_stat.o mdb.o idl.o

181
libraries/libmdb/mdb.c
View File

@ -7,8 +7,7 @@
#ifdef HAVE_SYS_FILE_H
#include <sys/file.h>
#endif
#include <sys/ipc.h>
#include <sys/shm.h>
#include <fcntl.h>
#include <assert.h>
#include <err.h>
@ -218,6 +217,7 @@ struct MDB_txn {
} mt_u;
#define MDB_TXN_RDONLY 0x01 /* read-only transaction */
#define MDB_TXN_ERROR 0x02 /* an error has occurred */
#define MDB_TXN_METOGGLE 0x04 /* used meta page 1 */
unsigned int mt_flags;
};
@ -233,10 +233,9 @@ struct MDB_db {
struct MDB_env {
int me_fd;
key_t me_shmkey;
int me_lfd;
uint32_t me_flags;
int me_maxreaders;
int me_metatoggle;
unsigned int me_maxreaders;
char *me_path;
char *me_map;
MDB_txninfo *me_txns;
@ -274,7 +273,7 @@ static int mdb_search_page(MDB_db *db,
static int mdbenv_read_header(MDB_env *env);
static int mdb_check_meta_page(MDB_page *p);
static int mdbenv_read_meta(MDB_env *env);
static int mdbenv_read_meta(MDB_env *env, int *which);
static int mdbenv_write_meta(MDB_txn *txn);
static MDB_page *mdbenv_get_page(MDB_env *env, pgno_t pgno);
@ -473,7 +472,7 @@ int
mdb_txn_begin(MDB_env *env, int rdonly, MDB_txn **ret)
{
MDB_txn *txn;
int rc;
int rc, toggle;
if ((txn = calloc(1, sizeof(*txn))) == NULL) {
DPRINTF("calloc: %s", strerror(errno));
@ -504,7 +503,7 @@ mdb_txn_begin(MDB_env *env, int rdonly, MDB_txn **ret)
if (rdonly) {
MDB_reader *r = pthread_getspecific(env->me_txkey);
if (!r) {
int i;
unsigned int i;
pthread_mutex_lock(&env->me_txns->mt_mutex);
for (i=0; i<env->me_maxreaders; i++) {
if (env->me_txns->mt_readers[i].mr_pid == 0) {
@ -529,11 +528,14 @@ mdb_txn_begin(MDB_env *env, int rdonly, MDB_txn **ret)
txn->mt_env = env;
if ((rc = mdbenv_read_meta(env)) != MDB_SUCCESS) {
if ((rc = mdbenv_read_meta(env, &toggle)) != MDB_SUCCESS) {
mdb_txn_abort(txn);
return rc;
}
if (toggle)
txn->mt_flags |= MDB_TXN_METOGGLE;
txn->mt_next_pgno = env->me_meta.mm_last_pg+1;
txn->mt_root = env->me_meta.mm_root;
DPRINTF("begin transaction %lu on mdbenv %p, root page %lu",
@ -839,7 +841,7 @@ mdbenv_write_meta(MDB_txn *txn)
meta.mm_txnid = txn->mt_txnid;
off = 0;
if (!env->me_metatoggle)
if (!F_ISSET(txn->mt_flags, MDB_TXN_METOGGLE))
off = env->me_meta.mm_stat.ms_psize;
off += PAGEHDRSZ;
@ -867,7 +869,7 @@ mdb_check_meta_page(MDB_page *p)
}
static int
mdbenv_read_meta(MDB_env *env)
mdbenv_read_meta(MDB_env *env, int *which)
{
MDB_page *mp0, *mp1;
MDB_meta *meta[2];
@ -893,7 +895,8 @@ mdbenv_read_meta(MDB_env *env)
if (meta[toggle]->mm_txnid > env->me_meta.mm_txnid) {
bcopy(meta[toggle], &env->me_meta, sizeof(env->me_meta));
env->me_metatoggle = toggle;
if (which)
*which = toggle;
}
DPRINTF("Using meta page %d", toggle);
@ -912,6 +915,8 @@ mdbenv_create(MDB_env **env)
e->me_meta.mm_mapsize = DEFAULT_MAPSIZE;
e->me_maxreaders = DEFAULT_READERS;
e->me_db.md_env = e;
e->me_fd = -1;
e->me_lfd = -1;
*env = e;
return MDB_SUCCESS;
}
@ -977,7 +982,7 @@ mdbenv_open2(MDB_env *env, unsigned int flags)
}
}
if ((i = mdbenv_read_meta(env)) != 0)
if ((i = mdbenv_read_meta(env, NULL)) != 0)
return i;
DPRINTF("opened database version %u, pagesize %u",
@ -1002,51 +1007,131 @@ mdbenv_reader_dest(void *ptr)
reader->mr_tid = 0;
}
int
mdbenv_open(MDB_env *env, const char *path, unsigned int flags, mode_t mode)
static void
mdbenv_share_locks(MDB_env *env)
{
int oflags, rc, shmid;
off_t size;
struct flock lock_info;
env->me_txns->mt_txnid = env->me_meta.mm_txnid;
if (F_ISSET(flags, MDB_RDONLY))
oflags = O_RDONLY;
else
oflags = O_RDWR | O_CREAT;
memset((void *)&lock_info, 0, sizeof(lock_info));
lock_info.l_type = F_RDLCK;
lock_info.l_whence = SEEK_SET;
lock_info.l_start = 0;
lock_info.l_len = 1;
fcntl(env->me_lfd, F_SETLK, &lock_info);
}
if ((env->me_fd = open(path, oflags, mode)) == -1)
return errno;
static int
mdbenv_setup_locks(MDB_env *env, char *lpath, int mode, int *excl)
{
int rc;
off_t size, rsize;
struct flock lock_info;
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);
if (env->me_txns->mt_magic != MDB_MAGIC ||
env->me_txns->mt_version != MDB_VERSION) {
DPRINTF("invalid lock region %d", shmid);
shmdt(env->me_txns);
env->me_txns = NULL;
return EIO;
}
} else {
return errno;
*excl = 0;
if ((env->me_lfd = open(lpath, O_RDWR|O_CREAT, mode)) == -1) {
rc = errno;
return rc;
}
/* Try to get exclusive lock. If we succeed, then
* nobody is using the lock region and we should initialize it.
*/
memset((void *)&lock_info, 0, sizeof(lock_info));
lock_info.l_type = F_WRLCK;
lock_info.l_whence = SEEK_SET;
lock_info.l_start = 0;
lock_info.l_len = 1;
rc = fcntl(env->me_lfd, F_SETLK, &lock_info);
if (rc == 0) {
*excl = 1;
} else {
lock_info.l_type = F_RDLCK;
rc = fcntl(env->me_lfd, F_SETLK, &lock_info);
if (rc) {
rc = errno;
goto fail;
}
}
size = lseek(env->me_lfd, 0, SEEK_END);
rsize = (env->me_maxreaders-1) * sizeof(MDB_reader) + sizeof(MDB_txninfo);
if (size < rsize && *excl) {
if (ftruncate(env->me_lfd, rsize) != 0) {
rc = errno;
goto fail;
}
} 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) {
rc = errno;
goto fail;
}
if (*excl) {
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);
env->me_txns->mt_version = MDB_VERSION;
env->me_txns->mt_magic = MDB_MAGIC;
env->me_txns->mt_txnid = 0;
env->me_txns->mt_numreaders = 0;
} else {
if (env->me_txns->mt_magic != MDB_MAGIC) {
DPRINTF("lock region has invalid magic");
errno = EINVAL;
}
if (env->me_txns->mt_version != MDB_VERSION) {
DPRINTF("lock region is version %u, expected version %u",
env->me_txns->mt_version, MDB_VERSION);
errno = EINVAL;
}
if (errno != EACCES && errno != EAGAIN) {
rc = errno;
goto fail;
}
}
return MDB_SUCCESS;
fail:
close(env->me_lfd);
return rc;
}
int
mdbenv_open(MDB_env *env, const char *path, unsigned int flags, mode_t mode)
{
int oflags, rc, len, excl;
char *lpath, *dpath;
len = strlen(path);
lpath = malloc(len + sizeof("/lock.mdb") + len + sizeof("/data.db"));
if (!lpath)
return ENOMEM;
dpath = lpath + len + sizeof("/lock.mdb");
sprintf(lpath, "%s/lock.mdb", path);
sprintf(dpath, "%s/data.mdb", path);
rc = mdbenv_setup_locks(env, lpath, mode, &excl);
if (rc)
goto leave;
if (F_ISSET(flags, MDB_RDONLY))
oflags = O_RDONLY;
else
oflags = O_RDWR | O_CREAT;
if ((env->me_fd = open(dpath, oflags, mode)) == -1)
return errno;
if ((rc = mdbenv_open2(env, flags)) != MDB_SUCCESS) {
close(env->me_fd);
@ -1054,10 +1139,14 @@ mdbenv_open(MDB_env *env, const char *path, unsigned int flags, mode_t mode)
} else {
env->me_path = strdup(path);
DPRINTF("opened dbenv %p", (void *) env);
pthread_key_create(&env->me_txkey, mdbenv_reader_dest);
if (excl)
mdbenv_share_locks(env);
}
pthread_key_create(&env->me_txkey, mdbenv_reader_dest);
leave:
free(lpath);
return rc;
}
@ -1074,8 +1163,10 @@ mdbenv_close(MDB_env *env)
}
close(env->me_fd);
if (env->me_txns) {
shmdt(env->me_txns);
size_t size = (env->me_maxreaders-1) * sizeof(MDB_reader) + sizeof(MDB_txninfo);
munmap(env->me_txns, size);
}
close(env->me_lfd);
free(env);
}
@ -1295,7 +1386,7 @@ mdb_search_page(MDB_db *db, MDB_txn *txn, MDB_val *key,
* committed root page.
*/
if (txn == NULL) {
if ((rc = mdbenv_read_meta(db->md_env)) != MDB_SUCCESS)
if ((rc = mdbenv_read_meta(db->md_env, NULL)) != MDB_SUCCESS)
return rc;
root = db->md_env->me_meta.mm_root;
} else if (F_ISSET(txn->mt_flags, MDB_TXN_ERROR)) {