475 lines
10 KiB
C++
475 lines
10 KiB
C++
#include "config.h"
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#ifdef OLD_DB_COMPAT
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#include "db.hh"
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#include "util.hh"
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#include "pathlocks.hh"
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#include <sys/types.h>
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#include <sys/stat.h>
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#include <fcntl.h>
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#include <errno.h>
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#include <memory>
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#include <db_cxx.h>
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namespace nix {
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/* Wrapper class to ensure proper destruction. */
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class DestroyDbc
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{
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Dbc * dbc;
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public:
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DestroyDbc(Dbc * _dbc) : dbc(_dbc) { }
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~DestroyDbc() { dbc->close(); /* close() frees dbc */ }
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};
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class DestroyDbEnv
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{
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DbEnv * dbenv;
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public:
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DestroyDbEnv(DbEnv * _dbenv) : dbenv(_dbenv) { }
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~DestroyDbEnv() {
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if (dbenv) {
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if (dbenv->get_DB_ENV()) dbenv->close(0);
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delete dbenv;
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}
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}
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void release() { dbenv = 0; };
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};
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static void rethrow(DbException & e)
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{
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throw Error(e.what());
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}
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Transaction::Transaction()
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: txn(0)
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{
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}
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Transaction::Transaction(Database & db)
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: txn(0)
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{
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begin(db);
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}
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Transaction::~Transaction()
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{
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if (txn) abort();
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}
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void Transaction::begin(Database & db)
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{
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assert(txn == 0);
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db.requireEnv();
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try {
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db.env->txn_begin(0, &txn, 0);
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} catch (DbException e) { rethrow(e); }
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}
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void Transaction::commit()
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{
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if (!txn) throw Error("commit called on null transaction");
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debug(format("committing transaction %1%") % (void *) txn);
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DbTxn * txn2 = txn;
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txn = 0;
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try {
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txn2->commit(0);
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} catch (DbException e) { rethrow(e); }
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}
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void Transaction::abort()
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{
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if (!txn) throw Error("abort called on null transaction");
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debug(format("aborting transaction %1%") % (void *) txn);
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DbTxn * txn2 = txn;
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txn = 0;
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try {
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txn2->abort();
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} catch (DbException e) { rethrow(e); }
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}
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void Transaction::moveTo(Transaction & t)
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{
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if (t.txn) throw Error("target txn already exists");
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t.txn = txn;
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txn = 0;
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}
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void Database::requireEnv()
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{
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checkInterrupt();
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if (!env) throw Error("database environment is not open "
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"(maybe you don't have sufficient permission?)");
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}
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Db * Database::getDb(TableId table)
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{
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if (table == 0)
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throw Error("database table is not open "
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"(maybe you don't have sufficient permission?)");
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std::map<TableId, Db *>::iterator i = tables.find(table);
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if (i == tables.end())
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throw Error("unknown table id");
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return i->second;
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}
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Database::Database()
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: env(0)
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, nextId(1)
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{
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}
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Database::~Database()
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{
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close();
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}
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void openEnv(DbEnv * & env, const string & path, u_int32_t flags)
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{
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try {
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createDirs(path);
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} catch (SysError & e) {
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if (e.errNo == EPERM || e.errNo == EACCES)
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throw DbNoPermission(format("cannot create the Nix database in `%1%'") % path);
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else
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throw;
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}
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try {
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env->open(path.c_str(),
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DB_INIT_LOCK | DB_INIT_LOG | DB_INIT_MPOOL | DB_INIT_TXN |
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DB_CREATE | flags,
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0666);
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} catch (DbException & e) {
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printMsg(lvlError, format("environment open failed: %1%") % e.what());
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throw;
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}
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}
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static int my_fsync(int fd)
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{
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return 0;
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}
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static void errorPrinter(const DbEnv * env, const char * errpfx, const char * msg)
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{
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printMsg(lvlError, format("Berkeley DB error: %1%") % msg);
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}
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static void messagePrinter(const DbEnv * env, const char * msg)
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{
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printMsg(lvlError, format("Berkeley DB message: %1%") % msg);
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}
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void Database::open2(const string & path, bool removeOldEnv)
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{
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if (env) throw Error(format("environment already open"));
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debug(format("opening database environment"));
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/* Create the database environment object. */
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DbEnv * env = new DbEnv(0);
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DestroyDbEnv deleteEnv(env);
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env->set_errcall(errorPrinter);
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env->set_msgcall(messagePrinter);
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if (getEnv("NIX_DEBUG_DB_REGISTER") == "1")
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env->set_verbose(DB_VERB_REGISTER, 1);
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env->set_verbose(DB_VERB_RECOVERY, 1);
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/* Smaller log files. */
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env->set_lg_bsize(32 * 1024); /* default */
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env->set_lg_max(256 * 1024); /* must be > 4 * lg_bsize */
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/* Write the log, but don't sync. This protects transactions
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against application crashes, but if the system crashes, some
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transactions may be undone. An acceptable risk, I think. */
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env->set_flags(DB_TXN_WRITE_NOSYNC | DB_LOG_AUTOREMOVE, 1);
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/* Increase the locking limits. If you ever get `Dbc::get: Cannot
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allocate memory' or similar, especially while running
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`nix-store --verify', just increase the following number, then
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run db_recover on the database to remove the existing DB
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environment (since changes only take effect on new
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environments). */
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env->set_lk_max_locks(10000);
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env->set_lk_max_lockers(10000);
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env->set_lk_max_objects(10000);
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env->set_lk_detect(DB_LOCK_DEFAULT);
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/* Dangerous, probably, but from the docs it *seems* that BDB
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shouldn't sync when DB_TXN_WRITE_NOSYNC is used, but it still
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fsync()s sometimes. */
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db_env_set_func_fsync(my_fsync);
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if (removeOldEnv) {
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printMsg(lvlError, "removing old Berkeley DB database environment...");
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env->remove(path.c_str(), DB_FORCE);
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return;
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}
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openEnv(env, path, DB_REGISTER | DB_RECOVER);
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deleteEnv.release();
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this->env = env;
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}
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void Database::open(const string & path)
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{
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try {
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open2(path, false);
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} catch (DbException e) {
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if (e.get_errno() == DB_VERSION_MISMATCH) {
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/* Remove the environment while we are holding the global
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lock. If things go wrong there, we bail out.
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!!! argh, we abolished the global lock :-( */
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open2(path, true);
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/* Try again. */
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open2(path, false);
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/* Force a checkpoint, as per the BDB docs. */
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env->txn_checkpoint(DB_FORCE, 0, 0);
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printMsg(lvlError, "database succesfully upgraded to new version");
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}
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#if 0
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else if (e.get_errno() == DB_RUNRECOVERY) {
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/* If recovery is needed, do it. */
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printMsg(lvlError, "running recovery...");
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open2(path, false, true);
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}
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#endif
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else
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rethrow(e);
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}
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}
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void Database::close()
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{
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if (!env) return;
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/* Close the database environment. */
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debug(format("closing database environment"));
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try {
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for (std::map<TableId, Db *>::iterator i = tables.begin();
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i != tables.end(); )
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{
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std::map<TableId, Db *>::iterator j = i;
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++j;
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closeTable(i->first);
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i = j;
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}
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/* Do a checkpoint every 128 kilobytes, or every 5 minutes. */
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env->txn_checkpoint(128, 5, 0);
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env->close(0);
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} catch (DbException e) { rethrow(e); }
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delete env;
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env = 0;
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}
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TableId Database::openTable(const string & tableName, bool sorted)
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{
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requireEnv();
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TableId table = nextId++;
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try {
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Db * db = new Db(env, 0);
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try {
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db->open(0, tableName.c_str(), 0,
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sorted ? DB_BTREE : DB_HASH,
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DB_CREATE | DB_AUTO_COMMIT, 0666);
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} catch (...) {
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delete db;
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throw;
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}
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tables[table] = db;
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} catch (DbException e) { rethrow(e); }
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return table;
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}
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void Database::closeTable(TableId table)
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{
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try {
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Db * db = getDb(table);
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db->close(DB_NOSYNC);
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delete db;
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tables.erase(table);
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} catch (DbException e) { rethrow(e); }
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}
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void Database::deleteTable(const string & table)
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{
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try {
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env->dbremove(0, table.c_str(), 0, DB_AUTO_COMMIT);
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} catch (DbException e) { rethrow(e); }
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}
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bool Database::queryString(const Transaction & txn, TableId table,
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const string & key, string & data)
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{
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checkInterrupt();
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try {
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Db * db = getDb(table);
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Dbt kt((void *) key.c_str(), key.length());
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Dbt dt;
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int err = db->get(txn.txn, &kt, &dt, 0);
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if (err) return false;
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if (!dt.get_data())
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data = "";
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else
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data = string((char *) dt.get_data(), dt.get_size());
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} catch (DbException e) { rethrow(e); }
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return true;
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}
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bool Database::queryStrings(const Transaction & txn, TableId table,
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const string & key, Strings & data)
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{
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string d;
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if (!queryString(txn, table, key, d))
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return false;
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data = unpackStrings(d);
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return true;
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}
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void Database::setString(const Transaction & txn, TableId table,
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const string & key, const string & data)
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{
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checkInterrupt();
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try {
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Db * db = getDb(table);
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Dbt kt((void *) key.c_str(), key.length());
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Dbt dt((void *) data.c_str(), data.length());
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db->put(txn.txn, &kt, &dt, 0);
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} catch (DbException e) { rethrow(e); }
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}
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void Database::setStrings(const Transaction & txn, TableId table,
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const string & key, const Strings & data, bool deleteEmpty)
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{
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if (deleteEmpty && data.size() == 0)
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delPair(txn, table, key);
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else
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setString(txn, table, key, packStrings(data));
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}
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void Database::delPair(const Transaction & txn, TableId table,
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const string & key)
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{
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checkInterrupt();
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try {
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Db * db = getDb(table);
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Dbt kt((void *) key.c_str(), key.length());
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db->del(txn.txn, &kt, 0);
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/* Non-existence of a pair with the given key is not an
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error. */
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} catch (DbException e) { rethrow(e); }
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}
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void Database::enumTable(const Transaction & txn, TableId table,
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Strings & keys, const string & keyPrefix)
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{
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try {
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Db * db = getDb(table);
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Dbc * dbc;
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db->cursor(txn.txn, &dbc, 0);
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DestroyDbc destroyDbc(dbc);
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Dbt kt, dt;
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u_int32_t flags = DB_NEXT;
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if (!keyPrefix.empty()) {
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flags = DB_SET_RANGE;
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kt = Dbt((void *) keyPrefix.c_str(), keyPrefix.size());
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}
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while (dbc->get(&kt, &dt, flags) != DB_NOTFOUND) {
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checkInterrupt();
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string data((char *) kt.get_data(), kt.get_size());
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if (!keyPrefix.empty() &&
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string(data, 0, keyPrefix.size()) != keyPrefix)
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break;
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keys.push_back(data);
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flags = DB_NEXT;
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}
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} catch (DbException e) { rethrow(e); }
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}
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void Database::clearTable(const Transaction & txn, TableId table)
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{
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try {
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Db * db = getDb(table);
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u_int32_t count;
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db->truncate(txn.txn, &count, 0);
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} catch (DbException e) { rethrow(e); }
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}
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}
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#endif
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