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manager: when we sweep the tree when looking for ordering cycles, remember and reuse if we already decided a tree was loop free, to improve speed drastically

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Lennart Poettering 2010-06-03 03:00:47 +02:00
parent 2279955bb5
commit 23e3c58809
1 changed files with 22 additions and 12 deletions
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34
src/manager.c
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@ -964,20 +964,25 @@ static int transaction_verify_order_one(Manager *m, Job *j, Job *from, unsigned
/* Does a recursive sweep through the ordering graph, looking
* for a cycle. If we find cycle we try to break it. */
/* Did we find a cycle? */
if (j->marker && j->generation == generation) {
/* Have we seen this before? */
if (j->generation == generation) {
Job *k;
/* So, we already have been here. We have a
* cycle. Let's try to break it. We go backwards in
* our path and try to find a suitable job to
* remove. We use the marker to find our way back,
* since smart how we are we stored our way back in
* there. */
/* If the marker is NULL we have been here already and
* decided the job was loop-free from here. Hence
* shortcut things and return right-away. */
if (!j->marker)
return 0;
/* So, the marker is not NULL and we already have been
* here. We have a cycle. Let's try to break it. We go
* backwards in our path and try to find a suitable
* job to remove. We use the marker to find our way
* back, since smart how we are we stored our way back
* in there. */
log_debug("Found ordering cycle on %s/%s", j->unit->meta.id, job_type_to_string(j->type));
for (k = from; k; k = (k->generation == generation ? k->marker : NULL)) {
for (k = from; k; k = ((k->generation == generation && k->marker != k) ? k->marker : NULL)) {
log_debug("Walked on cycle path to %s/%s", k->unit->meta.id, job_type_to_string(k->type));
@ -1002,8 +1007,10 @@ static int transaction_verify_order_one(Manager *m, Job *j, Job *from, unsigned
}
/* Make the marker point to where we come from, so that we can
* find our way backwards if we want to break a cycle */
j->marker = from;
* find our way backwards if we want to break a cycle. We use
* a special marker for the beginning: we point to
* ourselves. */
j->marker = from ? from : j;
j->generation = generation;
/* We assume that the the dependencies are bidirectional, and
@ -1035,6 +1042,7 @@ static int transaction_verify_order(Manager *m, unsigned *generation) {
Job *j;
int r;
Iterator i;
unsigned g;
assert(m);
assert(generation);
@ -1042,8 +1050,10 @@ static int transaction_verify_order(Manager *m, unsigned *generation) {
/* Check if the ordering graph is cyclic. If it is, try to fix
* that up by dropping one of the jobs. */
g = (*generation)++;
HASHMAP_FOREACH(j, m->transaction_jobs, i)
if ((r = transaction_verify_order_one(m, j, NULL, (*generation)++)) < 0)
if ((r = transaction_verify_order_one(m, j, NULL, g)) < 0)
return r;
return 0;