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authorLennart Poettering <lennart@poettering.net>2010-01-21 02:59:12 +0100
committerLennart Poettering <lennart@poettering.net>2010-01-21 02:59:12 +0100
commite094e853a047e10f0d2989eed76b6aa430e3ea1a (patch)
tree29acb378f3f659399c474ba516ca02ae6051a59d /manager.c
parent1ffba6fe82d65f2a87b53a21c7927bca8176038c (diff)
make sure impact of transactions is minimized
Diffstat (limited to 'manager.c')
-rw-r--r--manager.c75
1 files changed, 67 insertions, 8 deletions
diff --git a/manager.c b/manager.c
index 94ad680eb4..b1193b0ce3 100644
--- a/manager.c
+++ b/manager.c
@@ -244,9 +244,14 @@ static int transaction_merge_jobs(Manager *m) {
JobType t = j->type;
Job *k;
+ /* Merge all transactions */
for (k = j->transaction_next; k; k = k->transaction_next)
assert_se(job_type_merge(&t, k->type) == 0);
+ /* If an active job is mergable, merge it too */
+ if (j->name->meta.job)
+ job_type_merge(&t, j->name->meta.job->type); /* Might fail. Which is OK */
+
while ((k = j->transaction_next)) {
if (j->linked) {
transaction_merge_and_delete_job(m, k, j, t);
@@ -399,15 +404,61 @@ static int transaction_is_destructive(Manager *m, JobMode mode) {
/* Checks whether applying this transaction means that
* existing jobs would be replaced */
- HASHMAP_FOREACH(j, m->transaction_jobs, state)
+ HASHMAP_FOREACH(j, m->transaction_jobs, state) {
+
+ /* Assume merged */
+ assert(!j->transaction_prev);
+ assert(!j->transaction_next);
+
if (j->name->meta.job &&
j->name->meta.job != j &&
!job_type_is_superset(j->type, j->name->meta.job->type))
return -EEXIST;
+ }
return 0;
}
+static void transaction_minimize_impact(Manager *m) {
+ bool again;
+ assert(m);
+
+ /* Drops all unnecessary jobs that reverse already active jobs
+ * or that stop a running service. */
+
+ do {
+ Job *j;
+ void *state;
+
+ again = false;
+
+ HASHMAP_FOREACH(j, m->transaction_jobs, state) {
+ for (; j; j = j->transaction_next) {
+
+ /* If it matters, we shouldn't drop it */
+ if (j->matters_to_anchor)
+ continue;
+
+ /* Would this stop a running service?
+ * Would this change an existing job?
+ * If so, let's drop this entry */
+ if ((j->type != JOB_STOP || name_is_dead(j->name)) &&
+ (!j->name->meta.job || job_type_is_conflicting(j->type, j->name->meta.job->state)))
+ continue;
+
+ /* Ok, let's get rid of this */
+ transaction_delete_job(m, j);
+ again = true;
+ break;
+ }
+
+ if (again)
+ break;
+ }
+
+ } while (again);
+}
+
static int transaction_apply(Manager *m, JobMode mode) {
void *state;
Job *j;
@@ -416,6 +467,10 @@ static int transaction_apply(Manager *m, JobMode mode) {
/* Moves the transaction jobs to the set of active jobs */
HASHMAP_FOREACH(j, m->transaction_jobs, state) {
+ /* Assume merged */
+ assert(!j->transaction_prev);
+ assert(!j->transaction_next);
+
if (j->linked)
continue;
@@ -461,7 +516,6 @@ rollback:
return r;
}
-
static int transaction_activate(Manager *m, JobMode mode) {
int r;
unsigned generation = 1;
@@ -474,12 +528,17 @@ static int transaction_activate(Manager *m, JobMode mode) {
/* First step: figure out which jobs matter */
transaction_find_jobs_that_matter_to_anchor(m, NULL, generation++);
+ /* Second step: Try not to stop any running services if
+ * we don't have to. Don't try to reverse running
+ * jobs if we don't have to. */
+ transaction_minimize_impact(m);
+
for (;;) {
- /* Second step: Let's remove unneeded jobs that might
+ /* Third step: Let's remove unneeded jobs that might
* be lurking. */
transaction_collect_garbage(m);
- /* Third step: verify order makes sense and correct
+ /* Fourth step: verify order makes sense and correct
* cycles if necessary and possible */
if ((r = transaction_verify_order(m, &generation)) >= 0)
break;
@@ -492,7 +551,7 @@ static int transaction_activate(Manager *m, JobMode mode) {
}
for (;;) {
- /* Fourth step: let's drop unmergable entries if
+ /* Fifth step: let's drop unmergable entries if
* necessary and possible, merge entries we can
* merge */
if ((r = transaction_merge_jobs(m)) >= 0)
@@ -501,7 +560,7 @@ static int transaction_activate(Manager *m, JobMode mode) {
if (r != -EAGAIN)
goto rollback;
- /* Fifth step: an entry got dropped, let's garbage
+ /* Sixth step: an entry got dropped, let's garbage
* collect its dependencies. */
transaction_collect_garbage(m);
@@ -509,12 +568,12 @@ static int transaction_activate(Manager *m, JobMode mode) {
* unmergable entries ... */
}
- /* Sith step: check whether we can actually apply this */
+ /* Seventh step: check whether we can actually apply this */
if (mode == JOB_FAIL)
if ((r = transaction_is_destructive(m, mode)) < 0)
goto rollback;
- /* Seventh step: apply changes */
+ /* Eights step: apply changes */
if ((r = transaction_apply(m, mode)) < 0)
goto rollback;