From 0ad01db952718d3437fa8f077a065d17efe5279b Mon Sep 17 00:00:00 2001 From: Michal Schmidt Date: Tue, 24 Feb 2015 19:45:17 +0100 Subject: [PATCH] journal: make skipping of exhausted journal files effective again Commit 668c965af "journal: skipping of exhausted journal files is bad if direction changed" fixed a correctness issue, but it also significantly limited the cases where the optimization that skips exhausted journal files could apply. As a result, some journalctl queries are much slower in v219 than in v218. (e.g. queries where a "--since" cutoff should have quickly eliminated older journal files from consideration, but didn't.) If already in the initial iteration find_location_with_matches() finds no entry, the journal file's location is not updated. This is fine, except that: - We must update at least f->last_direction. The optimization relies on it. Let's separate that from journal_file_save_location() and update it immediately after the direction checks. - The optimization was conditional on "f->current_offset > 0", but it would always be 0 in this scenario. This check is unnecessary for the optimization. (cherry picked from commit 950c07d421c04e5aae99973479f4f13131fb45e1) --- src/journal/journal-file.c | 3 +-- src/journal/journal-file.h | 2 +- src/journal/sd-journal.c | 24 +++++++++++++++--------- 3 files changed, 17 insertions(+), 12 deletions(-) diff --git a/src/journal/journal-file.c b/src/journal/journal-file.c index 0f28718b0..24c49b916 100644 --- a/src/journal/journal-file.c +++ b/src/journal/journal-file.c @@ -2014,8 +2014,7 @@ void journal_file_reset_location(JournalFile *f) { f->current_xor_hash = 0; } -void journal_file_save_location(JournalFile *f, direction_t direction, Object *o, uint64_t offset) { - f->last_direction = direction; +void journal_file_save_location(JournalFile *f, Object *o, uint64_t offset) { f->location_type = LOCATION_SEEK; f->current_offset = offset; f->current_seqnum = le64toh(o->entry.seqnum); diff --git a/src/journal/journal-file.h b/src/journal/journal-file.h index 2526e14d6..403c8f760 100644 --- a/src/journal/journal-file.h +++ b/src/journal/journal-file.h @@ -199,7 +199,7 @@ int journal_file_find_field_object(JournalFile *f, const void *field, uint64_t s int journal_file_find_field_object_with_hash(JournalFile *f, const void *field, uint64_t size, uint64_t hash, Object **ret, uint64_t *offset); void journal_file_reset_location(JournalFile *f); -void journal_file_save_location(JournalFile *f, direction_t direction, Object *o, uint64_t offset); +void journal_file_save_location(JournalFile *f, Object *o, uint64_t offset); int journal_file_compare_locations(JournalFile *af, JournalFile *bf); int journal_file_next_entry(JournalFile *f, uint64_t p, direction_t direction, Object **ret, uint64_t *offset); diff --git a/src/journal/sd-journal.c b/src/journal/sd-journal.c index 94891cdf3..9b57e5945 100644 --- a/src/journal/sd-journal.c +++ b/src/journal/sd-journal.c @@ -723,13 +723,17 @@ static int next_beyond_location(sd_journal *j, JournalFile *f, direction_t direc assert(j); assert(f); - if (f->last_direction == direction && f->current_offset > 0) { - /* If we hit EOF before, recheck if any new entries arrived. */ - n_entries = le64toh(f->header->n_entries); - if (f->location_type == LOCATION_TAIL && n_entries == f->last_n_entries) - return 0; - f->last_n_entries = n_entries; + n_entries = le64toh(f->header->n_entries); + + /* If we hit EOF before, we don't need to look into this file again + * unless direction changed or new entries appeared. */ + if (f->last_direction == direction && f->location_type == LOCATION_TAIL && + n_entries == f->last_n_entries) + return 0; + f->last_n_entries = n_entries; + + if (f->last_direction == direction && f->current_offset > 0) { /* LOCATION_SEEK here means we did the work in a previous * iteration and the current location already points to a * candidate entry. */ @@ -738,14 +742,16 @@ static int next_beyond_location(sd_journal *j, JournalFile *f, direction_t direc if (r <= 0) return r; - journal_file_save_location(f, direction, c, cp); + journal_file_save_location(f, c, cp); } } else { + f->last_direction = direction; + r = find_location_with_matches(j, f, direction, &c, &cp); if (r <= 0) return r; - journal_file_save_location(f, direction, c, cp); + journal_file_save_location(f, c, cp); } /* OK, we found the spot, now let's advance until an entry @@ -773,7 +779,7 @@ static int next_beyond_location(sd_journal *j, JournalFile *f, direction_t direc if (r <= 0) return r; - journal_file_save_location(f, direction, c, cp); + journal_file_save_location(f, c, cp); } }