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Merge pull request #29402 from yuwata/sd-journal-cleanups-for-generic-array-bisect

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sd-journal: cleanups for generic_array_bisect()
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Luca Boccassi 2023-11-04 10:38:03 +00:00 committed by GitHub
commit 00cf9b3b1d
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2 changed files with 152 additions and 72 deletions
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222
src/libsystemd/sd-journal/journal-file.c
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@ -2870,36 +2870,38 @@ static int generic_array_get(
}
enum {
TEST_FOUND,
TEST_LEFT,
TEST_RIGHT
TEST_FOUND, /* The current object passes the test. */
TEST_LEFT, /* The current object is in an earlier position, and the object we are looking
* for should exist in a later position. */
TEST_RIGHT, /* The current object is in a later position, and the object we are looking for
* should exist in an earlier position. */
TEST_GOTO_NEXT, /* No matching object exists in this array and earlier arrays, go to the next array. */
TEST_GOTO_PREVIOUS, /* No matching object exists in this array and later arrays, go to the previous array. */
};
static int generic_array_bisect_one(
static int generic_array_bisect_step(
JournalFile *f,
uint64_t a, /* offset of entry array object. */
uint64_t i, /* index of the entry item we will test. */
Object *array, /* entry array object */
uint64_t i, /* index of the entry item in the array we will test. */
uint64_t needle,
int (*test_object)(JournalFile *f, uint64_t p, uint64_t needle),
direction_t direction,
uint64_t *left,
uint64_t *right,
uint64_t *ret_offset) {
uint64_t *m, /* The maximum number of the entries we will check in the array. */
uint64_t *left, /* The index of the left boundary in the array. */
uint64_t *right) { /* The index of the right boundary in the array. */
Object *array;
uint64_t p;
int r;
assert(f);
assert(array);
assert(test_object);
assert(m);
assert(left);
assert(right);
assert(*left <= i);
assert(i <= *right);
r = journal_file_move_to_object(f, OBJECT_ENTRY_ARRAY, a, &array);
if (r < 0)
return r;
assert(*right < *m);
p = journal_file_entry_array_item(f, array, i);
if (p <= 0)
@ -2908,52 +2910,80 @@ static int generic_array_bisect_one(
r = test_object(f, p, needle);
if (IN_SET(r, -EBADMSG, -EADDRNOTAVAIL)) {
log_debug_errno(r, "Encountered invalid entry while bisecting, cutting algorithm short.");
*right = i;
return -ENOANO; /* recognizable error */
/* The first entry in the array is corrupted, let's go back to the previous array. */
if (i == 0)
return TEST_GOTO_PREVIOUS;
/* Otherwise, cutting the array short. So, here we limit the number of elements we will see
* in this array, and set the right boundary to the last possibly non-corrupted object. */
*m = i;
*right = i - 1;
return TEST_RIGHT;
}
if (r < 0)
return r;
if (r == TEST_FOUND)
/* There may be multiple entries that match with the needle. When the direction is down, we
* need to find the first matching entry, hence the right boundary can be moved, but the left
* one cannot. Similarly, when the direction is up, we need to find the last matching entry,
* hence the left boundary can be moved, but the right one cannot. */
r = direction == DIRECTION_DOWN ? TEST_RIGHT : TEST_LEFT;
if (r == TEST_RIGHT)
*right = i;
else
*left = i + 1;
if (r == TEST_RIGHT) {
/* Currently, left --- needle --- i --- right, hence we can move the right boundary to i. */
if (direction == DIRECTION_DOWN)
*right = i;
else {
if (i == 0)
return TEST_GOTO_PREVIOUS;
*right = i - 1;
}
} else {
/* Currently, left --- i --- needle --- right, hence we can move the left boundary to i. */
if (direction == DIRECTION_DOWN) {
/* Note, here *m is always positive, as by the assertions at the beginning, we have
* 0 <= *left <= i <= *right < m */
if (i == *m - 1)
return TEST_GOTO_NEXT;
if (ret_offset)
*ret_offset = p;
*left = i + 1;
} else
*left = i;
}
return r;
}
static int generic_array_bisect(
JournalFile *f,
uint64_t first,
uint64_t n,
uint64_t needle,
int (*test_object)(JournalFile *f, uint64_t p, uint64_t needle),
uint64_t first, /* The offset of the first entry array object in the chain. */
uint64_t n, /* The total number of elements in the chain of the entry array. */
uint64_t needle, /* The target value (e.g. seqnum, monotonic, realtime, ...). */
int (*test_object)(JournalFile *f,
uint64_t p, /* the offset of the (data or entry) object that will be tested. */
uint64_t needle),
direction_t direction,
Object **ret_object,
uint64_t *ret_offset,
uint64_t *ret_idx) {
Object **ret_object, /* The found object. */
uint64_t *ret_offset, /* The offset of the found object. */
uint64_t *ret_idx) { /* The index of the found object counted from the beginning of the entry array chain. */
/* Given an entry array chain, this function finds the object "closest" to the given needle in the
* chain, taking into account the provided direction. A function can be provided to determine how
* an object is matched against the given needle.
*
* Given a journal file, the offset of an object and the needle, the test_object() function should
* return TEST_LEFT if the needle is located earlier in the entry array chain, TEST_LEFT if the
* needle is located later in the entry array chain and TEST_FOUND if the object matches the needle.
* return TEST_RIGHT if the needle is located earlier in the entry array chain, TEST_LEFT if the
* needle is located later in the entry array chain, and TEST_FOUND if the object matches the needle.
* If test_object() returns TEST_FOUND for a specific object, that object's information will be used
* to populate the return values of this function. If test_object() never returns TEST_FOUND, the
* return values are populated with the details of one of the objects closest to the needle. If the
* direction is DIRECTION_UP, the earlier object is used. Otherwise, the later object is used.
*/
* If there are multiple objects that test_object() return TEST_FOUND for, then the first matching
* object returned when direction is DIRECTION_DOWN. Otherwise the last object is returned. */
uint64_t a, p, t = 0, i = 0, last_p = 0, last_index = UINT64_MAX;
bool subtract_one = false;
uint64_t a, p, t = 0, i, last_index = UINT64_MAX;
ChainCacheItem *ci;
Object *array;
int r;
@ -2961,6 +2991,9 @@ static int generic_array_bisect(
assert(f);
assert(test_object);
if (n <= 0)
return 0;
/* Start with the first array in the chain */
a = first;
@ -2986,73 +3019,92 @@ static int generic_array_bisect(
}
while (a > 0) {
uint64_t left = 0, right, k, lp;
uint64_t left, right, k, m;
r = journal_file_move_to_object(f, OBJECT_ENTRY_ARRAY, a, &array);
if (r < 0)
return r;
k = journal_file_entry_array_n_items(f, array);
right = MIN(k, n);
if (right <= 0)
m = MIN(k, n);
if (m <= 0)
return 0;
right--;
r = generic_array_bisect_one(f, a, right, needle, test_object, direction, &left, &right, &lp);
if (r == -ENOANO) {
n = right;
continue;
left = 0;
right = m - 1;
if (direction == DIRECTION_UP) {
/* If we're going upwards, the last entry of the previous array may pass the test,
* and the first entry of the current array may not pass. In that case, the last
* entry of the previous array must be returned. Hence, we need to test the first
* entry of the current array. */
r = generic_array_bisect_step(f, array, 0, needle, test_object, direction, &m, &left, &right);
if (r < 0)
return r;
if (r == TEST_GOTO_PREVIOUS)
goto previous;
}
/* Test the last entry of this array, to determine if we should go to the next array. */
r = generic_array_bisect_step(f, array, right, needle, test_object, direction, &m, &left, &right);
if (r < 0)
return r;
if (r == TEST_GOTO_PREVIOUS)
goto previous;
/* The expected entry should be in this array, (or the last entry of the previous array). */
if (r == TEST_RIGHT) {
/* If we cached the last index we looked at, let's try to not to jump too wildly
* around and see if we can limit the range to look at early to the immediate
* neighbors of the last index we looked at. */
if (last_index > 0 && last_index - 1 < right) {
r = generic_array_bisect_one(f, a, last_index - 1, needle, test_object, direction, &left, &right, NULL);
if (r < 0 && r != -ENOANO)
if (last_index > 0 && left < last_index - 1 && last_index - 1 < right) {
r = generic_array_bisect_step(f, array, last_index - 1, needle, test_object, direction, &m, &left, &right);
if (r < 0)
return r;
if (r == TEST_GOTO_PREVIOUS)
goto previous;
}
if (last_index < right) {
r = generic_array_bisect_one(f, a, last_index + 1, needle, test_object, direction, &left, &right, NULL);
if (r < 0 && r != -ENOANO)
if (last_index < UINT64_MAX && left < last_index + 1 && last_index + 1 < right) {
r = generic_array_bisect_step(f, array, last_index + 1, needle, test_object, direction, &m, &left, &right);
if (r < 0)
return r;
if (r == TEST_GOTO_PREVIOUS)
goto previous;
}
for (;;) {
if (left == right) {
if (direction == DIRECTION_UP)
subtract_one = true;
i = left;
goto found;
}
assert(left < right);
i = (left + right) / 2;
i = (left + right + (direction == DIRECTION_UP)) / 2;
r = generic_array_bisect_one(f, a, i, needle, test_object, direction, &left, &right, NULL);
if (r < 0 && r != -ENOANO)
r = generic_array_bisect_step(f, array, i, needle, test_object, direction, &m, &left, &right);
if (r < 0)
return r;
if (r == TEST_GOTO_PREVIOUS)
goto previous;
}
}
/* Not found in this array (or the last entry of this array should be returned), go to the next array. */
assert(r == (direction == DIRECTION_DOWN ? TEST_GOTO_NEXT : TEST_LEFT));
if (k >= n) {
if (direction == DIRECTION_UP) {
i = n;
subtract_one = true;
assert(n > 0);
i = n - 1;
goto found;
}
return 0;
}
last_p = lp;
n -= k;
t += k;
last_index = UINT64_MAX;
@ -3061,27 +3113,55 @@ static int generic_array_bisect(
return 0;
found:
if (subtract_one && t == 0 && i == 0)
previous:
/* Not found in the current array, return the last entry of the previous array. */
assert(r == TEST_GOTO_PREVIOUS);
/* The current array is the first in the chain. no previous array. */
if (t == 0)
return 0;
r = journal_file_move_to_object(f, OBJECT_ENTRY_ARRAY, a, &array);
if (r < 0)
return r;
/* When we are going downwards, there is no matching entries in the previous array. */
if (direction == DIRECTION_DOWN)
return 0;
/* Indicate to go to the previous array later. Note, do not move to the previous array here,
* as that may invalidate the current array object in the mmap cache and
* journal_file_entry_array_item() below may read invalid address. */
i = UINT64_MAX;
found:
p = journal_file_entry_array_item(f, array, 0);
if (p <= 0)
return -EBADMSG;
/* Let's cache this item for the next invocation */
chain_cache_put(f->chain_cache, ci, first, a, p, t, subtract_one ? (i > 0 ? i-1 : UINT64_MAX) : i);
chain_cache_put(f->chain_cache, ci, first, a, p, t, i);
if (subtract_one && i == 0)
p = last_p;
else if (subtract_one)
p = journal_file_entry_array_item(f, array, i - 1);
else
p = journal_file_entry_array_item(f, array, i);
if (i == UINT64_MAX) {
uint64_t m;
/* Get the last entry of the previous array. */
r = bump_entry_array(f, NULL, a, first, DIRECTION_UP, &a);
if (r <= 0)
return r;
r = journal_file_move_to_object(f, OBJECT_ENTRY_ARRAY, a, &array);
if (r < 0)
return r;
m = journal_file_entry_array_n_items(f, array);
if (m == 0 || t < m)
return -EBADMSG;
t -= m;
i = m - 1;
}
p = journal_file_entry_array_item(f, array, i);
if (p == 0)
return -EBADMSG;
if (ret_object) {
r = journal_file_move_to_object(f, OBJECT_ENTRY, p, ret_object);
@ -3093,7 +3173,7 @@ found:
*ret_offset = p;
if (ret_idx)
*ret_idx = t + i + (subtract_one ? -1 : 0);
*ret_idx = t + i;
return 1;
}

2
test/units/testsuite-04.journal.sh
View File

@ -238,6 +238,6 @@ done < <(find /test-journals/no-rtc -name "*.zst")
journalctl --directory="$JOURNAL_DIR" --list-boots --output=json >/tmp/lb1
diff -u /tmp/lb1 - <<'EOF'
[{"index":-3,"boot_id":"5ea5fc4f82a14186b5332a788ef9435e","first_entry":1666569600994371,"last_entry":1666584266223608},{"index":-2,"boot_id":"bea6864f21ad4c9594c04a99d89948b0","first_entry":1666569601005945,"last_entry":1666584347230411},{"index":-1,"boot_id":"4c708e1fd0744336be16f3931aa861fb","first_entry":1666569601017222,"last_entry":1666584354649355},{"index":0,"boot_id":"35e8501129134edd9df5267c49f744a4","first_entry":1666569601009823,"last_entry":1666584438086856}]
[{"index":-3,"boot_id":"5ea5fc4f82a14186b5332a788ef9435e","first_entry":1666569600994371,"last_entry":1666584266223608},{"index":-2,"boot_id":"bea6864f21ad4c9594c04a99d89948b0","first_entry":1666569601005945,"last_entry":1666584347230411},{"index":-1,"boot_id":"4c708e1fd0744336be16f3931aa861fb","first_entry":1666584293354007,"last_entry":1666584354649355},{"index":0,"boot_id":"35e8501129134edd9df5267c49f744a4","first_entry":1666569601009823,"last_entry":1666584438086856}]
EOF
rm -rf "$JOURNAL_DIR" /tmp/lb1