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Relaced G_DATABASES rwlock with a mutex.

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Jon Meredith 2009-06-19 09:54:05 -06:00 committed by Phillip Toland
parent 425d8ddf00
commit 783acf09ba
2 changed files with 42 additions and 97 deletions
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3
Rakefile
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@ -9,8 +9,9 @@ INT_TEST_FLAGS << '+A10'
DB_LIB = "c_src/system/lib/libdb.a"
CC_FLAGS << "-Ic_src/system/include"
CC_FLAGS << "-Ic_src/system/include -pthread"
LD_LIBS << DB_LIB
LD_FLAGS << "-pthread"
file DB_LIB do
sh "cd c_src && ./buildlib.sh 2>&1"

136
c_src/bdberl_drv.c
View file

@ -133,14 +133,14 @@ static int G_DB_ENV_ERROR = 0;
* filenames to array index for an opened Database.
*
* All access to G_DATABASES and G_DATABASES_NAMES must be protected by the read/write lock
* G_DATABASES_RWLOCK.
* G_DATABASES_MUTEX.
*/
static Database* G_DATABASES = 0;
static Database* G_DATABASES_SHADOW = 0;
static unsigned int G_DATABASES_SIZE = 0;
static ErlDrvRWLock* G_DATABASES_RWLOCK = 0;
static volatile ErlDrvTid G_DATABASES_RWLOCK_TID = 0; /* TID for writers */
static volatile ErlDrvPort G_DATABASES_RWLOCK_PORT = 0; /* Port for writers */
static ErlDrvMutex* G_DATABASES_MUTEX = 0;
static volatile ErlDrvTid G_DATABASES_MUTEX_TID = 0;
static volatile ErlDrvPort G_DATABASES_MUTEX_PORT = 0;
static hive_hash* G_DATABASES_NAMES = 0;
@ -237,68 +237,35 @@ void CHECK_DATABASES(void)
}
}
void READ_LOCK_DATABASES(void *x, ErlDrvPort P)
void LOCK_DATABASES(ErlDrvPort P)
{
#ifdef DEBUG
ErlDrvTid self = erl_drv_thread_self();
#endif
DBG("threadid %p port %p: read locking G_DATABASES\r\n", self, P);
DBG("threadid %p port %p: locking G_DATABASES\r\n", self, P);
erl_drv_mutex_lock(G_DATABASES_MUTEX);
CHECK_DATABASES();
erl_drv_rwlock_rlock(G_DATABASES_RWLOCK);
assert(0 == G_DATABASES_RWLOCK_TID);
assert(0 == G_DATABASES_RWLOCK_PORT);
assert(0 == G_DATABASES_MUTEX_TID);
assert(0 == G_DATABASES_MUTEX_PORT);
G_DATABASES_MUTEX_TID = self;
G_DATABASES_MUTEX_PORT = P;
assert(0 == memcmp(G_DATABASES, G_DATABASES_SHADOW, sizeof(G_DATABASES[0])*G_DATABASES_SIZE));
DBG("threadid %p port %p: read locked G_DATABASES\r\n", self, P);
DBG("threadid %p port %p: locked G_DATABASES\r\n", self, P);
}
void READ_UNLOCK_DATABASES(void *x, ErlDrvPort P)
{
#ifdef DEBUG
ErlDrvTid self = erl_drv_thread_self();
#endif
DBG("threadid %p port %p: read unlocking G_DATABASES\r\n", self, P);
assert(0 == G_DATABASES_RWLOCK_TID);
assert(0 == G_DATABASES_RWLOCK_PORT);
assert(0 == memcmp(G_DATABASES, G_DATABASES_SHADOW, sizeof(G_DATABASES[0])*G_DATABASES_SIZE));
CHECK_DATABASES();
erl_drv_rwlock_runlock(G_DATABASES_RWLOCK);
DBG("threadid %p port %p: read unlocked G_DATABASES\r\n", self, P);
}
#define PROMOTE_READ_LOCK_DATABASES(L, P) \
READ_UNLOCK_DATABASES(L, P); \
WRITE_LOCK_DATABASES(L, P);
void WRITE_LOCK_DATABASES(void *x, ErlDrvPort P)
void UNLOCK_DATABASES(ErlDrvPort P)
{
ErlDrvTid self = erl_drv_thread_self();
DBG("threadid %p port %p: write locking G_DATABASES\r\n", self, P);
erl_drv_rwlock_rwlock(G_DATABASES_RWLOCK);
CHECK_DATABASES();
assert(0 == memcmp(G_DATABASES, G_DATABASES_SHADOW, sizeof(G_DATABASES[0])*G_DATABASES_SIZE));
assert(0 == G_DATABASES_RWLOCK_TID);
assert(0 == G_DATABASES_RWLOCK_PORT);
G_DATABASES_RWLOCK_TID = self;
G_DATABASES_RWLOCK_PORT = P;
DBG("threadid %p port %p: write locked G_DATABASES\r\n", self, P);
}
void WRITE_UNLOCK_DATABASES(void *x, ErlDrvPort P)
{
#ifdef DEBUG
ErlDrvTid self = erl_drv_thread_self();
#endif
DBG("threadid %p port %p: write unlocking G_DATABASES\r\n", self, P);
assert(erl_drv_thread_self() == G_DATABASES_RWLOCK_TID);
assert(P == G_DATABASES_RWLOCK_PORT);
DBG("threadid %p port %p: unlocking G_DATABASES\r\n", self, P);
assert(self == G_DATABASES_MUTEX_TID);
assert(P == G_DATABASES_MUTEX_PORT);
memcpy(G_DATABASES_SHADOW, G_DATABASES, sizeof(G_DATABASES[0])*G_DATABASES_SIZE);
G_DATABASES_RWLOCK_TID = 0;
G_DATABASES_RWLOCK_PORT = 0;
G_DATABASES_MUTEX_TID = 0;
G_DATABASES_MUTEX_PORT = 0;
CHECK_DATABASES();
erl_drv_rwlock_rwunlock(G_DATABASES_RWLOCK);
DBG("threadid %p port %p: write unlocked G_DATABASES\r\n", self, P);
erl_drv_mutex_unlock(G_DATABASES_MUTEX);
DBG("threadid %p port %p: unlocked G_DATABASES\r\n", self, P);
}
#define READ_LOCK(L) erl_drv_rwlock_rlock(L)
#define READ_UNLOCK(L) erl_drv_rwlock_runlock(L)
#define PROMOTE_READ_LOCK(L) erl_drv_rwlock_runlock(L); erl_drv_rwlock_rwlock(L)
@ -398,7 +365,7 @@ DRIVER_INIT(bdberl_drv)
G_DATABASES_SHADOW = (Database*) driver_alloc(sizeof(Database) * G_DATABASES_SIZE);
memset(G_DATABASES, '\0', sizeof(Database) * G_DATABASES_SIZE);
memcpy(G_DATABASES_SHADOW, G_DATABASES, sizeof(Database) * G_DATABASES_SIZE);
G_DATABASES_RWLOCK = erl_drv_rwlock_create("bdberl_drv: G_DATABASES_RWLOCK");
G_DATABASES_MUTEX = erl_drv_mutex_create("bdberl_drv: G_DATABASES_MUTEX");
G_DATABASES_NAMES = hive_hash_new(G_DATABASES_SIZE);
// Startup deadlock check thread
@ -620,10 +587,10 @@ static void bdberl_drv_finish()
driver_free(G_DATABASES_SHADOW);
G_DATABASES = NULL;
}
if (NULL != G_DATABASES_RWLOCK)
if (NULL != G_DATABASES_MUTEX)
{
erl_drv_rwlock_destroy(G_DATABASES_RWLOCK);
G_DATABASES_RWLOCK = NULL;
erl_drv_mutex_destroy(G_DATABASES_MUTEX);
G_DATABASES_MUTEX = NULL;
}
if (NULL != G_DATABASES_NAMES)
@ -1074,7 +1041,7 @@ static int open_database(const char* name, DBTYPE type, unsigned int flags, Port
{
*dbref_res = -1;
READ_LOCK_DATABASES(G_DATABASES_RWLOCK, data->port);
LOCK_DATABASES(data->port);
// Look up the database by name in our hash table
Database* database = (Database*)hive_hash_get(G_DATABASES_NAMES, name);
@ -1088,47 +1055,24 @@ static int open_database(const char* name, DBTYPE type, unsigned int flags, Port
// Database structure in G_DATABASES
if (add_dbref(data, dbref))
{
// Need to update G_DATABASES -- grab the write lock
PROMOTE_READ_LOCK_DATABASES(G_DATABASES_RWLOCK, data->port);
// Add a reference to this port
add_portref(dbref, data->port);
// Release RW lock and return the ref
WRITE_UNLOCK_DATABASES(G_DATABASES_RWLOCK, data->port);
UNLOCK_DATABASES(data->port);
*dbref_res = dbref;
return 0;
}
else
{
// Already in our list of opened databases -- unlock and return the reference
READ_UNLOCK_DATABASES(G_DATABASES_RWLOCK, data->port);
UNLOCK_DATABASES(data->port);
*dbref_res = dbref;
return 0;
}
}
else
{
// This database hasn't been opened yet -- grab a write lock
PROMOTE_READ_LOCK_DATABASES(G_DATABASES_RWLOCK, data->port);
// While waiting on the write lock, another thread could have slipped in and
// opened the database, so do one more check to see if the database is already
// open
database = (Database*)hive_hash_get(G_DATABASES_NAMES, name);
if (database)
{
// Database got created while we were waiting on the write lock, add a reference
// to our port and drop the lock ASAP
int dbref = database - G_DATABASES;
add_portref(dbref, data->port);
WRITE_UNLOCK_DATABASES(G_DATABASES_RWLOCK, data->port);
add_dbref(data, dbref);
*dbref_res = dbref;
return 0;
}
{
// Database hasn't been created while we were waiting on write lock, so
// create/open it
@ -1138,7 +1082,7 @@ static int open_database(const char* name, DBTYPE type, unsigned int flags, Port
if (dbref < 0)
{
// No more slots available
WRITE_UNLOCK_DATABASES(G_DATABASES_RWLOCK, data->port);
UNLOCK_DATABASES(data->port);
return ERROR_MAX_DBS;
}
@ -1151,7 +1095,7 @@ static int open_database(const char* name, DBTYPE type, unsigned int flags, Port
{
// Failure while creating the database handle -- drop our lock and return
// the code
WRITE_UNLOCK_DATABASES(G_DATABASES_RWLOCK, data->port);
UNLOCK_DATABASES(data->port);
return rc;
}
@ -1173,7 +1117,7 @@ static int open_database(const char* name, DBTYPE type, unsigned int flags, Port
// Failure while opening the database -- cleanup the handle, drop the lock
// and return
db->close(db, 0);
WRITE_UNLOCK_DATABASES(G_DATABASES_RWLOCK, data->port);
UNLOCK_DATABASES(data->port);
return rc;
}
@ -1189,7 +1133,7 @@ static int open_database(const char* name, DBTYPE type, unsigned int flags, Port
hive_hash_add(G_DATABASES_NAMES, G_DATABASES[dbref].name, &(G_DATABASES[dbref]));
// Drop the write lock
WRITE_UNLOCK_DATABASES(G_DATABASES_RWLOCK, data->port);
UNLOCK_DATABASES(data->port);
// Add the dbref to the port list
add_dbref(data, dbref);
@ -1205,7 +1149,7 @@ static int close_database(int dbref, unsigned flags, PortData* data)
{
// Something was actually deleted from our list -- now we need to disassociate the
// calling port with the global database structure.
WRITE_LOCK_DATABASES(G_DATABASES_RWLOCK, data->port);
LOCK_DATABASES(data->port);
assert(G_DATABASES[dbref].db != 0);
assert(G_DATABASES[dbref].ports != 0);
@ -1232,7 +1176,7 @@ static int close_database(int dbref, unsigned flags, PortData* data)
memset(database, '\0', sizeof(Database));
}
WRITE_UNLOCK_DATABASES(G_DATABASES_RWLOCK, data->port);
UNLOCK_DATABASES(data->port);
return rc;
}
else
@ -1247,7 +1191,7 @@ static int close_database(int dbref, unsigned flags, PortData* data)
// but it is very important for BDB to shutdown cleanly so a final check can't hurt.
static void check_all_databases_closed()
{
WRITE_LOCK_DATABASES(G_DATABASES_RWLOCK, (ErlDrvPort)-1); // use unlikely port number - have no port here.
LOCK_DATABASES((ErlDrvPort)-1); // use unlikely port number - have no port here.
int dbref;
int rc;
@ -1269,7 +1213,7 @@ static void check_all_databases_closed()
}
}
WRITE_UNLOCK_DATABASES(G_DATABASES_RWLOCK, (ErlDrvPort)-1);
UNLOCK_DATABASES((ErlDrvPort)-1);
}
@ -1288,19 +1232,19 @@ static void abort_txn(PortData* d)
static int delete_database(const char* name, PortData *data)
{
// Go directly to a write lock on the global databases structure
WRITE_LOCK_DATABASES(G_DATABASES_RWLOCK, data->port);
LOCK_DATABASES(data->port);
// Make sure the database is not opened by anyone
if (hive_hash_get(G_DATABASES_NAMES, name))
{
WRITE_UNLOCK_DATABASES(G_DATABASES_RWLOCK, data->port);
UNLOCK_DATABASES(data->port);
return ERROR_DB_ACTIVE;
}
// Good, database doesn't seem to be open -- attempt the delete
DBG("Attempting to delete database: %s\r\n", name);
int rc = G_DB_ENV->dbremove(G_DB_ENV, 0, name, 0, DB_AUTO_COMMIT);
WRITE_UNLOCK_DATABASES(G_DATABASES_RWLOCK, data->port);
UNLOCK_DATABASES(data->port);
return rc;
}