diff options
| -rw-r--r-- | src/libstore/db.cc | 155 | ||||
| -rw-r--r-- | src/libstore/db.hh | 3 |
2 files changed, 56 insertions, 102 deletions
diff --git a/src/libstore/db.cc b/src/libstore/db.cc index 2c925134a..072b0bb97 100644 --- a/src/libstore/db.cc +++ b/src/libstore/db.cc @@ -20,6 +20,16 @@ public: }; +class DestroyDbEnv +{ + DbEnv * dbenv; +public: + DestroyDbEnv(DbEnv * _dbenv) : dbenv(_dbenv) { } + ~DestroyDbEnv() { if (dbenv) { dbenv->close(0); delete dbenv; } } + void release() { dbenv = 0; }; +}; + + static void rethrow(DbException & e) { throw Error(e.what()); @@ -150,12 +160,17 @@ void setAccessorCount(int fd, int n) } -void openEnv(DbEnv * env, const string & path, u_int32_t flags) +void openEnv(DbEnv * & env, const string & path, u_int32_t flags) { - env->open(path.c_str(), - DB_INIT_LOCK | DB_INIT_LOG | DB_INIT_MPOOL | DB_INIT_TXN | - DB_CREATE | flags, - 0666); + try { + env->open(path.c_str(), + DB_INIT_LOCK | DB_INIT_LOG | DB_INIT_MPOOL | DB_INIT_TXN | + DB_CREATE | flags, + 0666); + } catch (DbException & e) { + printMsg(lvlError, format("environment open failed: %1%") % e.what()); + throw; + } } @@ -165,6 +180,18 @@ static int my_fsync(int fd) } +static void errorPrinter(const DbEnv * env, const char * errpfx, const char * msg) +{ + printMsg(lvlError, format("Berkeley DB error: %1%") % msg); +} + + +static void messagePrinter(const DbEnv * env, const char * msg) +{ + printMsg(lvlError, format("Berkeley DB message: %1%") % msg); +} + + void Database::open2(const string & path, bool removeOldEnv) { if (env) throw Error(format("environment already open")); @@ -173,8 +200,13 @@ void Database::open2(const string & path, bool removeOldEnv) /* Create the database environment object. */ - DbEnv * env = 0; /* !!! close on error */ - env = new DbEnv(0); + DbEnv * env = new DbEnv(0); + DestroyDbEnv deleteEnv(env); + + env->set_errcall(errorPrinter); + env->set_msgcall(messagePrinter); + //env->set_verbose(DB_VERB_REGISTER, 1); + env->set_verbose(DB_VERB_RECOVERY, 1); /* Smaller log files. */ env->set_lg_bsize(32 * 1024); /* default */ @@ -200,93 +232,19 @@ void Database::open2(const string & path, bool removeOldEnv) shouldn't sync when DB_TXN_WRITE_NOSYNC is used, but it still fsync()s sometimes. */ db_env_set_func_fsync(my_fsync); - - /* The following code provides automatic recovery of the database - environment. Recovery is necessary when a process dies while - it has the database open. To detect this, processes atomically - increment a counter when they open the database, and decrement - it when they close it. If we see that counter is > 0 but no - processes are accessing the database---determined by attempting - to obtain a write lock on a lock file on which all accessors - have a read lock---we must run recovery. Note that this also - ensures that we only run recovery when there are no other - accessors (which could cause database corruption). */ - - /* !!! close fdAccessors / fdLock on exception */ - - /* Open the accessor count file. */ - string accessorsPath = path + "/accessor_count"; - fdAccessors = ::open(accessorsPath.c_str(), O_RDWR | O_CREAT, 0666); - if (fdAccessors == -1) - if (errno == EACCES) - throw DbNoPermission( - format("permission denied to database in `%1%'") % accessorsPath); - else - throw SysError(format("opening file `%1%'") % accessorsPath); - /* Open the lock file. */ - string lockPath = path + "/access_lock"; - fdLock = ::open(lockPath.c_str(), O_RDWR | O_CREAT, 0666); - if (fdLock == -1) - throw SysError(format("opening lock file `%1%'") % lockPath); - - /* Try to acquire a write lock. */ - debug(format("attempting write lock on `%1%'") % lockPath); - if (lockFile(fdLock, ltWrite, false)) { /* don't wait */ - - debug(format("write lock granted")); - - /* We have a write lock, which means that there are no other - readers or writers. */ - - if (removeOldEnv) { - printMsg(lvlError, "removing old Berkeley DB database environment..."); - env->remove(path.c_str(), DB_FORCE); - return; - } - - int n = getAccessorCount(fdAccessors); - - if (n != 0) { - printMsg(lvlTalkative, - format("accessor count is %1%, running recovery") % n); - - /* Open the environment after running recovery. */ - openEnv(env, path, DB_RECOVER); - } - - else - /* Open the environment normally. */ - openEnv(env, path, 0); - - setAccessorCount(fdAccessors, 1); - - /* Downgrade to a read lock. */ - debug(format("downgrading to read lock on `%1%'") % lockPath); - lockFile(fdLock, ltRead, true); + if (removeOldEnv) { + printMsg(lvlError, "removing old Berkeley DB database environment..."); + env->remove(path.c_str(), DB_FORCE); + return; + } - } else { - /* There are other accessors. */ - debug(format("write lock refused")); + openEnv(env, path, DB_REGISTER | DB_RECOVER); - /* Acquire a read lock. */ - debug(format("acquiring read lock on `%1%'") % lockPath); - lockFile(fdLock, ltRead, true); /* wait indefinitely */ - - /* Increment the accessor count. */ - lockFile(fdAccessors, ltWrite, true); - int n = getAccessorCount(fdAccessors) + 1; - setAccessorCount(fdAccessors, n); - debug(format("incremented accessor count to %1%") % n); - lockFile(fdAccessors, ltNone, true); - - /* Open the environment normally. */ - openEnv(env, path, 0); - } - + deleteEnv.release(); this->env = env; -} +} void Database::open(const string & path) @@ -310,6 +268,15 @@ void Database::open(const string & path) /* Force a checkpoint, as per the BDB docs. */ env->txn_checkpoint(DB_FORCE, 0, 0); } + +#if 0 + else if (e.get_errno() == DB_RUNRECOVERY) { + /* If recovery is needed, do it. */ + printMsg(lvlError, "running recovery..."); + open2(path, false, true); + } +#endif + else rethrow(e); } @@ -341,16 +308,6 @@ void Database::close() } catch (DbException e) { rethrow(e); } delete env; - - /* Decrement the accessor count. */ - lockFile(fdAccessors, ltWrite, true); - int n = getAccessorCount(fdAccessors) - 1; - setAccessorCount(fdAccessors, n); - debug(format("decremented accessor count to %1%") % n); - lockFile(fdAccessors, ltNone, true); - - ::close(fdAccessors); - ::close(fdLock); } diff --git a/src/libstore/db.hh b/src/libstore/db.hh index b962d77bc..76afc1d3b 100644 --- a/src/libstore/db.hh +++ b/src/libstore/db.hh @@ -48,9 +48,6 @@ class Database private: DbEnv * env; - int fdLock; - int fdAccessors; - TableId nextId; map<TableId, Db *> tables; |