Commit f367441b authored by Howard Chu's avatar Howard Chu
Browse files

Add locking support

parent a4c36262
......@@ -19,6 +19,7 @@
#include <string.h>
#include <time.h>
#include <unistd.h>
#include <pthread.h>
#include <openssl/sha.h>
......@@ -47,6 +48,46 @@
typedef ulong pgno_t;
typedef uint16_t indx_t;
#define DEFAULT_READERS 126
#define DEFAULT_MAPSIZE 1048576
/* Lock descriptor stuff */
#define RXBODY \
ulong mr_txnid; \
pid_t mr_pid; \
pthread_t mr_tid
typedef struct MDB_rxbody {
RXBODY;
} MDB_rxbody;
#ifndef CACHELINE
#define CACHELINE 64 /* most CPUs. Itanium uses 128 */
#endif
typedef struct MDB_reader {
RXBODY;
/* cache line alignment */
char pad[CACHELINE-sizeof(MDB_rxbody)];
} MDB_reader;
#define TXBODY \
uint32_t mt_magic; \
uint32_t mt_version; \
pthread_mutex_t mt_mutex; \
ulong mt_txnid; \
uint32_t mt_numreaders
typedef struct MDB_txbody {
TXBODY;
} MDB_txbody;
typedef struct MDB_txninfo {
TXBODY;
char pad[CACHELINE-sizeof(MDB_txbody)];
pthread_mutex_t mt_wmutex;
char pad2[CACHELINE-sizeof(pthread_mutex_t)];
MDB_reader mt_readers[1];
} MDB_txninfo;
/* Common header for all page types. Overflow pages
* occupy a number of contiguous pages with no
* headers on any page after the first.
......@@ -101,6 +142,7 @@ typedef struct MDB_meta { /* meta (footer) page content */
pgno_t mm_root; /* page number of root page */
MDB_stat mm_stat;
pgno_t mm_prev_meta; /* previous meta page number */
ulong mm_txnid;
#define MDB_TOMBSTONE 0x01 /* file is replaced */
uint32_t mm_flags;
#define mm_revisions mm_stat.ms_revisions
......@@ -171,8 +213,12 @@ struct MDB_txn {
pgno_t mt_root; /* current / new root page */
pgno_t mt_next_pgno; /* next unallocated page */
pgno_t mt_first_pgno;
ulong mt_txnid;
MDB_env *mt_env;
struct dirty_queue *mt_dirty_queue; /* modified pages */
union {
struct dirty_queue *dirty_queue; /* modified pages */
MDB_reader *reader;
} mt_u;
#define MDB_TXN_RDONLY 0x01 /* read-only transaction */
#define MDB_TXN_ERROR 0x02 /* an error has occurred */
unsigned int mt_flags;
......@@ -199,16 +245,20 @@ struct MDB_db {
struct MDB_env {
int me_fd;
int me_lfd;
#define MDB_FIXPADDING 0x01 /* internal */
uint32_t me_flags;
int me_maxreaders;
char *me_path;
char *me_map;
MDB_txninfo *me_txns;
MDB_head me_head;
MDB_db0 me_db; /* first DB, overlaps with meta */
MDB_meta me_meta;
MDB_txn *me_txn; /* current write transaction */
size_t me_mapsize;
off_t me_size; /* current file size */
pthread_key_t me_txkey; /* thread-key for readers */
};
#define NODESIZE offsetof(MDB_node, mn_data)
......@@ -356,7 +406,7 @@ mdb_newpage(MDB_txn *txn, MDB_page *parent, int parent_idx, int num)
dp->h.md_num = num;
dp->h.md_parent = parent;
dp->h.md_pi = parent_idx;
SIMPLEQ_INSERT_TAIL(txn->mt_dirty_queue, dp, h.md_next);
SIMPLEQ_INSERT_TAIL(txn->mt_u.dirty_queue, dp, h.md_next);
dp->p.mp_pgno = txn->mt_next_pgno;
txn->mt_next_pgno += num;
......@@ -410,11 +460,6 @@ mdb_txn_begin(MDB_env *env, int rdonly, MDB_txn **ret)
MDB_txn *txn;
int rc;
if (!rdonly && env->me_txn != NULL) {
DPRINTF("write transaction already begun");
return EBUSY;
}
if ((txn = calloc(1, sizeof(*txn))) == NULL) {
DPRINTF("calloc: %s", strerror(errno));
return ENOMEM;
......@@ -423,23 +468,40 @@ mdb_txn_begin(MDB_env *env, int rdonly, MDB_txn **ret)
if (rdonly) {
txn->mt_flags |= MDB_TXN_RDONLY;
} else {
txn->mt_dirty_queue = calloc(1, sizeof(*txn->mt_dirty_queue));
if (txn->mt_dirty_queue == NULL) {
txn->mt_u.dirty_queue = calloc(1, sizeof(*txn->mt_u.dirty_queue));
if (txn->mt_u.dirty_queue == NULL) {
free(txn);
return ENOMEM;
}
SIMPLEQ_INIT(txn->mt_dirty_queue);
SIMPLEQ_INIT(txn->mt_u.dirty_queue);
#if 0
DPRINTF("taking write lock on txn %p", txn);
if (flock(bt->fd, LOCK_EX | LOCK_NB) != 0) {
DPRINTF("flock: %s", strerror(errno));
errno = EBUSY;
free(txn->dirty_queue);
free(txn);
return NULL;
pthread_mutex_lock(&env->me_txns->mt_wmutex);
env->me_txns->mt_txnid++;
}
txn->mt_txnid = env->me_txns->mt_txnid;
if (rdonly) {
MDB_reader *r = pthread_getspecific(env->me_txkey);
if (!r) {
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) {
env->me_txns->mt_readers[i].mr_pid = getpid();
env->me_txns->mt_readers[i].mr_tid = pthread_self();
pthread_setspecific(env->me_txkey, &env->me_txns->mt_readers[i]);
if (i >= env->me_txns->mt_numreaders)
env->me_txns->mt_numreaders = i+1;
break;
}
}
pthread_mutex_unlock(&env->me_txns->mt_mutex);
if (i == env->me_maxreaders) {
return ENOSPC;
}
}
#endif
r->mr_txnid = txn->mt_txnid;
txn->mt_u.reader = r;
} else {
env->me_txn = txn;
}
......@@ -470,12 +532,14 @@ mdb_txn_abort(MDB_txn *txn)
env = txn->mt_env;
DPRINTF("abort transaction on mdbenv %p, root page %lu", env, txn->mt_root);
if (!F_ISSET(txn->mt_flags, MDB_TXN_RDONLY)) {
if (F_ISSET(txn->mt_flags, MDB_TXN_RDONLY)) {
txn->mt_u.reader->mr_txnid = 0;
} else {
/* Discard all dirty pages.
*/
while (!SIMPLEQ_EMPTY(txn->mt_dirty_queue)) {
dp = SIMPLEQ_FIRST(txn->mt_dirty_queue);
SIMPLEQ_REMOVE_HEAD(txn->mt_dirty_queue, h.md_next);
while (!SIMPLEQ_EMPTY(txn->mt_u.dirty_queue)) {
dp = SIMPLEQ_FIRST(txn->mt_u.dirty_queue);
SIMPLEQ_REMOVE_HEAD(txn->mt_u.dirty_queue, h.md_next);
free(dp);
}
......@@ -487,11 +551,11 @@ mdb_txn_abort(MDB_txn *txn)
txn->bt->fd, strerror(errno));
}
#endif
free(txn->mt_dirty_queue);
free(txn->mt_u.dirty_queue);
env->me_txn = NULL;
pthread_mutex_unlock(&env->me_txns->mt_wmutex);
}
if (txn == env->me_txn)
env->me_txn = NULL;
free(txn);
}
......@@ -528,7 +592,7 @@ mdb_txn_commit(MDB_txn *txn)
return EINVAL;
}
if (SIMPLEQ_EMPTY(txn->mt_dirty_queue))
if (SIMPLEQ_EMPTY(txn->mt_u.dirty_queue))
goto done;
if (F_ISSET(env->me_flags, MDB_FIXPADDING)) {
......@@ -552,7 +616,7 @@ mdb_txn_commit(MDB_txn *txn)
do {
n = 0;
done = 1;
SIMPLEQ_FOREACH(dp, txn->mt_dirty_queue, h.md_next) {
SIMPLEQ_FOREACH(dp, txn->mt_u.dirty_queue, h.md_next) {
DPRINTF("committing page %lu", dp->p.mp_pgno);
iov[n].iov_len = env->me_head.mh_psize * dp->h.md_num;
iov[n].iov_base = &dp->p;
......@@ -581,9 +645,9 @@ mdb_txn_commit(MDB_txn *txn)
/* Drop the dirty pages.
*/
while (!SIMPLEQ_EMPTY(txn->mt_dirty_queue)) {
dp = SIMPLEQ_FIRST(txn->mt_dirty_queue);
SIMPLEQ_REMOVE_HEAD(txn->mt_dirty_queue, h.md_next);
while (!SIMPLEQ_EMPTY(txn->mt_u.dirty_queue)) {
dp = SIMPLEQ_FIRST(txn->mt_u.dirty_queue);
SIMPLEQ_REMOVE_HEAD(txn->mt_u.dirty_queue, h.md_next);
free(dp);
if (--n == 0)
break;
......@@ -596,8 +660,9 @@ mdb_txn_commit(MDB_txn *txn)
mdb_txn_abort(txn);
return n;
}
txn = NULL;
env->me_txn = NULL;
pthread_mutex_unlock(&env->me_txns->mt_wmutex);
txn = NULL;
done:
mdb_txn_abort(txn);
......@@ -713,7 +778,7 @@ mdbenv_write_meta(MDB_env *env, pgno_t root, unsigned int flags)
bcopy(&env->me_meta, meta, sizeof(*meta));
rc = write(env->me_fd, &dp->p, env->me_head.mh_psize);
SIMPLEQ_REMOVE_HEAD(env->me_txn->mt_dirty_queue, h.md_next);
SIMPLEQ_REMOVE_HEAD(env->me_txn->mt_u.dirty_queue, h.md_next);
free(dp);
if (rc != (ssize_t)env->me_head.mh_psize) {
int err = errno;
......@@ -852,12 +917,38 @@ mdbenv_create(MDB_env **env, size_t size)
e->me_head.mh_magic = MDB_MAGIC;
e->me_head.mh_version = MDB_VERSION;
e->me_mapsize = e->me_head.mh_mapsize = size;
e->me_head.mh_mapsize = DEFAULT_MAPSIZE;
e->me_maxreaders = DEFAULT_READERS;
e->me_db.md_env = e;
*env = e;
return MDB_SUCCESS;
}
int
mdbenv_set_mapsize(MDB_env *env, size_t size)
{
if (env->me_map)
return EINVAL;
env->me_mapsize = env->me_head.mh_mapsize = size;
return MDB_SUCCESS;
}
int
mdbenv_set_maxreaders(MDB_env *env, int readers)
{
env->me_maxreaders = readers;
return MDB_SUCCESS;
}
int
mdbenv_get_maxreaders(MDB_env *env, int *readers)
{
if (!env || !readers)
return EINVAL;
*readers = env->me_maxreaders;
return MDB_SUCCESS;
}
int
mdbenv_open2(MDB_env *env, unsigned int flags)
{
......@@ -918,10 +1009,54 @@ mdbenv_open2(MDB_env *env, unsigned int flags)
return MDB_SUCCESS;
}
static void
mdbenv_reader_dest(void *ptr)
{
MDB_reader *reader = ptr;
reader->mr_txnid = 0;
reader->mr_pid = 0;
reader->mr_tid = 0;
}
int
mdbenv_open(MDB_env *env, const char *path, unsigned int flags, mode_t mode)
{
int oflags, rc;
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)
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;
}
} 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;
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;
......@@ -939,6 +1074,8 @@ mdbenv_open(MDB_env *env, const char *path, unsigned int flags, mode_t mode)
DPRINTF("opened dbenv %p", env);
}
pthread_key_create(&env->me_txkey, mdbenv_reader_dest);
return rc;
}
......@@ -954,6 +1091,12 @@ mdbenv_close(MDB_env *env)
munmap(env->me_map, env->me_mapsize);
}
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);
}
close(env->me_lfd);
free(env);
}
/* Search for key within a leaf page, using binary search.
......@@ -1060,9 +1203,9 @@ mdbenv_get_page(MDB_env *env, pgno_t pgno)
MDB_txn *txn = env->me_txn;
if (txn && pgno >= txn->mt_first_pgno &&
!SIMPLEQ_EMPTY(txn->mt_dirty_queue)) {
!SIMPLEQ_EMPTY(txn->mt_u.dirty_queue)) {
MDB_dpage *dp;
SIMPLEQ_FOREACH(dp, txn->mt_dirty_queue, h.md_next) {
SIMPLEQ_FOREACH(dp, txn->mt_u.dirty_queue, h.md_next) {
if (dp->p.mp_pgno == pgno) {
p = &dp->p;
break;
......
......@@ -55,12 +55,15 @@ typedef struct MDB_stat {
unsigned long ms_entries;
} MDB_stat;
int mdbenv_create(MDB_env **env, size_t size);
int mdbenv_create(MDB_env **env);
int mdbenv_open(MDB_env *env, const char *path, unsigned int flags, mode_t mode);
int mdbenv_stat(MDB_env *env, MDB_stat **stat);
void mdbenv_close(MDB_env *env);
int mdbenv_get_flags(MDB_env *env, unsigned int *flags);
int mdbenv_get_path(MDB_env *env, const char **path);
int mdbenv_set_mapsize(MDB_env *env, size_t size);
int mdbenv_set_maxreaders(MDB_env *env, int readers);
int mdbenv_get_maxreaders(MDB_env *env, int *readers);
int mdbenv_sync(MDB_env *env);
int mdbenv_compact(MDB_env *env);
......
......@@ -25,7 +25,8 @@ int main(int argc,char * argv[])
values[i] = random()%1024;
}
rc = mdbenv_create(&env, 10485760);
rc = mdbenv_create(&env);
rc = mdbenv_set_mapsize(env, 10485760);
rc = mdbenv_open(env, "./testdb", MDB_FIXEDMAP|MDB_NOSYNC, 0664);
rc = mdb_txn_begin(env, 0, &txn);
rc = mdb_open(env, txn, NULL, 0, &db);
......
Markdown is supported
0% or .
You are about to add 0 people to the discussion. Proceed with caution.
Finish editing this message first!
Please register or to comment