| /* trail.c : backing out of aborted Berkeley DB transactions |
| * |
| * ==================================================================== |
| * Licensed to the Apache Software Foundation (ASF) under one |
| * or more contributor license agreements. See the NOTICE file |
| * distributed with this work for additional information |
| * regarding copyright ownership. The ASF licenses this file |
| * to you under the Apache License, Version 2.0 (the |
| * "License"); you may not use this file except in compliance |
| * with the License. You may obtain a copy of the License at |
| * |
| * http://www.apache.org/licenses/LICENSE-2.0 |
| * |
| * Unless required by applicable law or agreed to in writing, |
| * software distributed under the License is distributed on an |
| * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY |
| * KIND, either express or implied. See the License for the |
| * specific language governing permissions and limitations |
| * under the License. |
| * ==================================================================== |
| */ |
| |
| #define SVN_WANT_BDB |
| #include "svn_private_config.h" |
| |
| #include <apr_pools.h> |
| #include "svn_pools.h" |
| #include "svn_fs.h" |
| #include "fs.h" |
| #include "err.h" |
| #include "bdb/bdb-err.h" |
| #include "bdb/bdb_compat.h" |
| #include "trail.h" |
| #include "../libsvn_fs/fs-loader.h" |
| |
| |
| #if defined(SVN_FS__TRAIL_DEBUG) |
| |
| struct trail_debug_t |
| { |
| struct trail_debug_t *prev; |
| const char *table; |
| const char *op; |
| }; |
| |
| void |
| svn_fs_base__trail_debug(trail_t *trail, const char *table, const char *op) |
| { |
| struct trail_debug_t *trail_debug; |
| |
| trail_debug = apr_palloc(trail->pool, sizeof(*trail_debug)); |
| trail_debug->prev = trail->trail_debug; |
| trail_debug->table = table; |
| trail_debug->op = op; |
| trail->trail_debug = trail_debug; |
| } |
| |
| static void |
| print_trail_debug(trail_t *trail, |
| const char *txn_body_fn_name, |
| const char *filename, int line) |
| { |
| struct trail_debug_t *trail_debug; |
| |
| fprintf(stderr, "(%s, %s, %u, %u): ", |
| txn_body_fn_name, filename, line, trail->db_txn ? 1 : 0); |
| |
| trail_debug = trail->trail_debug; |
| while (trail_debug) |
| { |
| fprintf(stderr, "(%s, %s) ", trail_debug->table, trail_debug->op); |
| trail_debug = trail_debug->prev; |
| } |
| fprintf(stderr, "\n"); |
| } |
| #else |
| #define print_trail_debug(trail, txn_body_fn_name, filename, line) |
| #endif /* defined(SVN_FS__TRAIL_DEBUG) */ |
| |
| |
| static svn_error_t * |
| begin_trail(trail_t **trail_p, |
| svn_fs_t *fs, |
| svn_boolean_t use_txn, |
| apr_pool_t *pool) |
| { |
| base_fs_data_t *bfd = fs->fsap_data; |
| trail_t *trail = apr_pcalloc(pool, sizeof(*trail)); |
| |
| trail->pool = svn_pool_create(pool); |
| trail->fs = fs; |
| if (use_txn) |
| { |
| /* [*] |
| If we're already inside a trail operation, abort() -- this is |
| a coding problem (and will likely hang the repository anyway). */ |
| SVN_ERR_ASSERT(! bfd->in_txn_trail); |
| |
| SVN_ERR(BDB_WRAP(fs, N_("beginning Berkeley DB transaction"), |
| bfd->bdb->env->txn_begin(bfd->bdb->env, 0, |
| &trail->db_txn, 0))); |
| bfd->in_txn_trail = TRUE; |
| } |
| else |
| { |
| trail->db_txn = NULL; |
| } |
| |
| *trail_p = trail; |
| return SVN_NO_ERROR; |
| } |
| |
| |
| static svn_error_t * |
| abort_trail(trail_t *trail) |
| { |
| svn_fs_t *fs = trail->fs; |
| base_fs_data_t *bfd = fs->fsap_data; |
| |
| if (trail->db_txn) |
| { |
| /* [**] |
| We have to reset the in_txn_trail flag *before* calling |
| DB_TXN->abort(). If we did it the other way around, the next |
| call to begin_trail() (e.g., as part of a txn retry) would |
| cause an abort, even though there's strictly speaking no |
| programming error involved (see comment [*] above). |
| |
| In any case, if aborting the txn fails, restarting it will |
| most likely fail for the same reason, and so it's better to |
| see the returned error than to abort. An obvious example is |
| when DB_TXN->abort() returns DB_RUNRECOVERY. */ |
| bfd->in_txn_trail = FALSE; |
| SVN_ERR(BDB_WRAP(fs, N_("aborting Berkeley DB transaction"), |
| trail->db_txn->abort(trail->db_txn))); |
| } |
| svn_pool_destroy(trail->pool); |
| |
| return SVN_NO_ERROR; |
| } |
| |
| |
| static svn_error_t * |
| commit_trail(trail_t *trail) |
| { |
| int db_err; |
| svn_fs_t *fs = trail->fs; |
| base_fs_data_t *bfd = fs->fsap_data; |
| |
| /* According to the example in the Berkeley DB manual, txn_commit |
| doesn't return DB_LOCK_DEADLOCK --- all deadlocks are reported |
| earlier. */ |
| if (trail->db_txn) |
| { |
| /* See comment [**] in abort_trail() above. |
| An error during txn commit will abort the transaction anyway. */ |
| bfd->in_txn_trail = FALSE; |
| SVN_ERR(BDB_WRAP(fs, N_("committing Berkeley DB transaction"), |
| trail->db_txn->commit(trail->db_txn, 0))); |
| } |
| |
| /* Do a checkpoint here, if enough has gone on. |
| The checkpoint parameters below are pretty arbitrary. Perhaps |
| there should be an svn_fs_berkeley_mumble function to set them. */ |
| db_err = bfd->bdb->env->txn_checkpoint(bfd->bdb->env, 1024, 5, 0); |
| |
| /* Pre-4.1 Berkeley documentation says: |
| |
| The DB_ENV->txn_checkpoint function returns a non-zero error |
| value on failure, 0 on success, and returns DB_INCOMPLETE if |
| there were pages that needed to be written to complete the |
| checkpoint but that DB_ENV->memp_sync was unable to write |
| immediately. |
| |
| It's safe to ignore DB_INCOMPLETE if we get it while |
| checkpointing. (Post-4.1 Berkeley doesn't have DB_INCOMPLETE |
| anymore, so it's not an issue there.) */ |
| if (db_err) |
| { |
| #if SVN_BDB_HAS_DB_INCOMPLETE |
| if (db_err != DB_INCOMPLETE) |
| #endif /* SVN_BDB_HAS_DB_INCOMPLETE */ |
| { |
| return svn_fs_bdb__wrap_db |
| (fs, "checkpointing after Berkeley DB transaction", db_err); |
| } |
| } |
| |
| return SVN_NO_ERROR; |
| } |
| |
| |
| static svn_error_t * |
| do_retry(svn_fs_t *fs, |
| svn_error_t *(*txn_body)(void *baton, trail_t *trail), |
| void *baton, |
| svn_boolean_t use_txn, |
| svn_boolean_t destroy_trail_pool, |
| apr_pool_t *pool, |
| const char *txn_body_fn_name, |
| const char *filename, |
| int line) |
| { |
| for (;;) |
| { |
| trail_t *trail; |
| svn_error_t *svn_err, *err; |
| svn_boolean_t deadlocked = FALSE; |
| |
| SVN_ERR(begin_trail(&trail, fs, use_txn, pool)); |
| |
| /* Do the body of the transaction. */ |
| svn_err = (*txn_body)(baton, trail); |
| |
| if (! svn_err) |
| { |
| /* The transaction succeeded! Commit it. */ |
| SVN_ERR(commit_trail(trail)); |
| |
| if (use_txn) |
| print_trail_debug(trail, txn_body_fn_name, filename, line); |
| |
| /* If our caller doesn't want us to keep trail memory |
| around, destroy our subpool. */ |
| if (destroy_trail_pool) |
| svn_pool_destroy(trail->pool); |
| |
| return SVN_NO_ERROR; |
| } |
| |
| /* Search for a deadlock error on the stack. */ |
| for (err = svn_err; err; err = err->child) |
| if (err->apr_err == SVN_ERR_FS_BERKELEY_DB_DEADLOCK) |
| deadlocked = TRUE; |
| |
| /* Is this a real error, or do we just need to retry? */ |
| if (! deadlocked) |
| { |
| /* Ignore any error returns. The first error is more valuable. */ |
| svn_error_clear(abort_trail(trail)); |
| return svn_err; |
| } |
| |
| svn_error_clear(svn_err); |
| |
| /* We deadlocked. Abort the transaction, and try again. */ |
| SVN_ERR(abort_trail(trail)); |
| } |
| } |
| |
| |
| svn_error_t * |
| svn_fs_base__retry_debug(svn_fs_t *fs, |
| svn_error_t *(*txn_body)(void *baton, trail_t *trail), |
| void *baton, |
| svn_boolean_t destroy_trail_pool, |
| apr_pool_t *pool, |
| const char *txn_body_fn_name, |
| const char *filename, |
| int line) |
| { |
| return do_retry(fs, txn_body, baton, TRUE, destroy_trail_pool, pool, |
| txn_body_fn_name, filename, line); |
| } |
| |
| |
| #if defined(SVN_FS__TRAIL_DEBUG) |
| #undef svn_fs_base__retry_txn |
| #endif |
| |
| svn_error_t * |
| svn_fs_base__retry_txn(svn_fs_t *fs, |
| svn_error_t *(*txn_body)(void *baton, trail_t *trail), |
| void *baton, |
| svn_boolean_t destroy_trail_pool, |
| apr_pool_t *pool) |
| { |
| return do_retry(fs, txn_body, baton, TRUE, destroy_trail_pool, pool, |
| "unknown", "", 0); |
| } |
| |
| |
| svn_error_t * |
| svn_fs_base__retry(svn_fs_t *fs, |
| svn_error_t *(*txn_body)(void *baton, trail_t *trail), |
| void *baton, |
| svn_boolean_t destroy_trail_pool, |
| apr_pool_t *pool) |
| { |
| return do_retry(fs, txn_body, baton, FALSE, destroy_trail_pool, pool, |
| NULL, NULL, 0); |
| } |
