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journal: compare candidate entries using JournalFiles' locations

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When comparing the locations of candidate entries, we can rely on the
location information stored in struct JournalFile.
This commit is contained in:
Michal Schmidt 2014-12-17 14:06:28 +01:00
parent 1eb6332d55
commit d8ae66d7fa
3 changed files with 54 additions and 85 deletions
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52
src/journal/journal-file.c
View file

@ -1949,6 +1949,58 @@ void journal_file_save_location(JournalFile *f, direction_t direction, Object *o
f->current_xor_hash = le64toh(o->entry.xor_hash);
}
int journal_file_compare_locations(JournalFile *af, JournalFile *bf) {
assert(af);
assert(bf);
assert(af->location_type == LOCATION_SEEK);
assert(bf->location_type == LOCATION_SEEK);
/* If contents and timestamps match, these entries are
* identical, even if the seqnum does not match */
if (sd_id128_equal(af->current_boot_id, bf->current_boot_id) &&
af->current_monotonic == bf->current_monotonic &&
af->current_realtime == bf->current_realtime &&
af->current_xor_hash == bf->current_xor_hash)
return 0;
if (sd_id128_equal(af->header->seqnum_id, bf->header->seqnum_id)) {
/* If this is from the same seqnum source, compare
* seqnums */
if (af->current_seqnum < bf->current_seqnum)
return -1;
if (af->current_seqnum > bf->current_seqnum)
return 1;
/* Wow! This is weird, different data but the same
* seqnums? Something is borked, but let's make the
* best of it and compare by time. */
}
if (sd_id128_equal(af->current_boot_id, bf->current_boot_id)) {
/* If the boot id matches, compare monotonic time */
if (af->current_monotonic < bf->current_monotonic)
return -1;
if (af->current_monotonic > bf->current_monotonic)
return 1;
}
/* Otherwise, compare UTC time */
if (af->current_realtime < bf->current_realtime)
return -1;
if (af->current_realtime > bf->current_realtime)
return 1;
/* Finally, compare by contents */
if (af->current_xor_hash < bf->current_xor_hash)
return -1;
if (af->current_xor_hash > bf->current_xor_hash)
return 1;
return 0;
}
int journal_file_next_entry(
JournalFile *f,
Object *o, uint64_t p,

1
src/journal/journal-file.h
View file

@ -197,6 +197,7 @@ int journal_file_find_field_object_with_hash(JournalFile *f, const void *field,
void journal_file_reset_location(JournalFile *f);
void journal_file_save_location(JournalFile *f, direction_t direction, Object *o, uint64_t offset);
int journal_file_compare_locations(JournalFile *af, JournalFile *bf);
int journal_file_next_entry(JournalFile *f, Object *o, uint64_t p, direction_t direction, Object **ret, uint64_t *offset);
int journal_file_next_entry_for_data(JournalFile *f, Object *o, uint64_t p, uint64_t data_offset, direction_t direction, Object **ret, uint64_t *offset);

86
src/journal/sd-journal.c
View file

@ -412,90 +412,6 @@ _public_ void sd_journal_flush_matches(sd_journal *j) {
detach_location(j);
}
static int compare_entry_order(JournalFile *af, Object *_ao,
JournalFile *bf, uint64_t bp) {
uint64_t a, b;
Object *ao, *bo;
int r;
assert(af);
assert(bf);
assert(_ao);
/* The mmap cache might invalidate the object from the first
* file if we look at the one from the second file. Hence
* temporarily copy the header of the first one, and look at
* that only. */
ao = alloca(offsetof(EntryObject, items));
memcpy(ao, _ao, offsetof(EntryObject, items));
r = journal_file_move_to_object(bf, OBJECT_ENTRY, bp, &bo);
if (r < 0)
return strcmp(af->path, bf->path);
/* We operate on two different files here, hence we can access
* two objects at the same time, which we normally can't.
*
* If contents and timestamps match, these entries are
* identical, even if the seqnum does not match */
if (sd_id128_equal(ao->entry.boot_id, bo->entry.boot_id) &&
ao->entry.monotonic == bo->entry.monotonic &&
ao->entry.realtime == bo->entry.realtime &&
ao->entry.xor_hash == bo->entry.xor_hash)
return 0;
if (sd_id128_equal(af->header->seqnum_id, bf->header->seqnum_id)) {
/* If this is from the same seqnum source, compare
* seqnums */
a = le64toh(ao->entry.seqnum);
b = le64toh(bo->entry.seqnum);
if (a < b)
return -1;
if (a > b)
return 1;
/* Wow! This is weird, different data but the same
* seqnums? Something is borked, but let's make the
* best of it and compare by time. */
}
if (sd_id128_equal(ao->entry.boot_id, bo->entry.boot_id)) {
/* If the boot id matches, compare monotonic time */
a = le64toh(ao->entry.monotonic);
b = le64toh(bo->entry.monotonic);
if (a < b)
return -1;
if (a > b)
return 1;
}
/* Otherwise, compare UTC time */
a = le64toh(ao->entry.realtime);
b = le64toh(bo->entry.realtime);
if (a < b)
return -1;
if (a > b)
return 1;
/* Finally, compare by contents */
a = le64toh(ao->entry.xor_hash);
b = le64toh(bo->entry.xor_hash);
if (a < b)
return -1;
if (a > b)
return 1;
return 0;
}
_pure_ static int compare_with_location(JournalFile *af, Object *ao, Location *l) {
uint64_t a;
@ -898,7 +814,7 @@ static int real_journal_next(sd_journal *j, direction_t direction) {
else {
int k;
k = compare_entry_order(f, o, new_file, new_offset);
k = journal_file_compare_locations(f, new_file);
found = direction == DIRECTION_DOWN ? k < 0 : k > 0;
}